The current research is focused on the hydrogen production through a two-step ZnO/Zn thermochemical water splitting cycle. In the present paper, numerical modeling of the second step is conducted using Computational Fluid Dynamics (CFD)2, where steam reacts with zinc to produce hydrogen. The parametric study shows that the hydrogen yield is relatively insensitive to the steam/zinc molar ratio and inversely proportional to the argon/steam molar ratio. For large argon to steam molar ratios, hydrogen yield is relatively insensitive to the inlet temperature of zinc and steam, and increases marginally with an increase in the argon inlet temperature. Five different reactor configurations were evaluated comprehensively. Among all configurations, a cylindrical reactor with a tangential inlet for argon and zinc, and a radial inlet for steam (both in the bottom plane of the reactor) and a tangential outlet in the top plane of the reactor produced the highest hydrogen yield of 88%. Copyright © 2013 John Wiley & Sons, Ltd.

The study presents 3D numerical modeling of ZnO/Zn hydrolysis step in a reactor. It proposes an improved reactor design by investigating the effect of different parameters and reactor configurations on hydrogen yield. It also discusses how flow velocity, temperature distribution, and Zinc particle residence time influence hydrogen yield. The figure shows contours of hydrogen gas concentration (kmol/m³) inside different reactor configurations.

Bioethanol is an alternative to fossil fuels in the transportation sector. The use of pellet for heating is also an efficient way to mitigate greenhouse gas emissions. This paper evaluates the techno-economic performance of a biorefinery system in which an existing combined heat and power (CHP) plant is integrated with the production of bioethanol and pellet using straw as feedstock. A two-stage acid hydrolysis process is used for bioethanol production, and two different drying technologies are applied to dry hydrolysis solid residues. A sensitivity analysis is performed on critical parameters such as the bioethanol selling price and feedstock price. The bioethanol production cost is also calculated for two cases with either 10 year or 15 year payback times. The results show that the second case is currently a more feasible economic configuration and reduces production costs by 36.4%–77.3% compared to other types of poly-generation plants that are not integrated into existing CHP plants. Copyright © 2013 John Wiley & Sons, Ltd.

Thermal modeling of temperature rise in high-power Li-ion battery cells and modules is presented here. Simulation results are validated by experiments. Results indicate that entropy heat generation plays a significant role in heat generation of Li-ion battery cells and should be included in simulation as a function of state of charge (SOC). Simulation results utilizing measured overpotential resistance and entropy heat generation provide the best fit when compared to experimental results. Resistance data provided by supplier shows significant difference compared with measured data and should be critically examined for any module design purposes. Copyright © 2013 John Wiley & Sons, Ltd.

Heat generated by change in entropy plays a significant part in the heat generation in Li-ion battery cell and should not be neglected. A DC resistance value is not enough for a proper thermal design of the battery module, and electrochemical reactions have to be taken into account.

Combining solid oxide fuel cell and gas turbine (SOFC/GT) system is a promising concept for future clean and efficient power generation. An SOFC/GT system exploits the complementary features of the two power plants, where the GT recuperates the energy in the SOFC exhaust stream and thereby boosts the overall system efficiency. Through model-based transient analysis, however, it is shown that the intricate coupling dynamics make the transient load following very challenging. The purpose of this study is to examine the load-following capability of 5-kW class SOFC/micro-GT hybrid systems in two different configurations: single-shaft and dual-shaft GT designs. An optimal load-following operation scheme, aimed at achieving a proper trade-off between high steady-state efficiency and fast transient response is developed through model-based dynamic analysis and optimization. Simulation results are reported to illustrate the effectiveness of the proposed optimal scheme. Copyright © 2013 John Wiley & Sons, Ltd.

Research Significance: The response characteristics of solid oxide fuel cell/micro-gas turbine hybrid systems for load changes have been identified. A computational framework which leads to an optimal load change strategy to achieve the fast load following has been established. Through case studies, the technique has proven very useful as a mathematical tool in providing quantitative assessments that allow design trade-off between the system efficiency and the fast load-following capability.

This paper deals with the energy production and economics of a large-scale biomass-based combined heat and power (CHP) plant. An activity-based costing model was developed for estimating the production costs of the heat and power of the bio-CHP. A 100 MW plant (58 MW heat, 29 MW electricity) was used as reference. The production process was divided into four stages: fuel handling, fluidized bed boiler, turbine plant, and flue gas cleaning. The boiler accounted for close to 50% of the production costs. The interest rates and the utilization rate of the CHP had a significant effect on the profitability. We found that below 4000–4500 h per year utilization, the electricity production turned unprofitable. However, the heat production remained profitable with high interest rate (10%) and a low utilization rate (4000 h). The profitability also depended on the type of biomass used. We found that, e.g. with moderate interest rates and high utilization rate of the plant, the bio-CHP plant could afford wood and Reed canary grass as fuel sources. Copyright © 2013 John Wiley & Sons, Ltd.

Methane hydrate is a kind of gas hydrate formed by physical binding between water molecules and methane gas, which is captured in the cavities of water molecules under a specific temperature and pressure. Pure methane hydrate of 1 m³ can be decomposed into methane gas of 172 m³ and water of 0.8 m³ at standard conditions. Methane hydrate has many practical applications such as separation processes, natural gas storage transportation, and carbon dioxide sequestration. For the industrial utilization of this substance, it is essential to find a rapid method of manufacturing it. This work studies the formation of methane hydrates by using tetrahydrofuran (THF) and oxidized carbon nanotubes (OMWCNTs) by testing different fluid mixtures of THF and carbon nanotubes. The results show that when the mixed fluid contained THF, the OMWCNTs showed the gas consumption 5.2 times that of distilled water at 3.4 K subcooling. Also, THF's effects as a thermodynamic phase equilibrium promoter were preserved when it was used with OMWCNTs. Therefore, it can be expected that when OMWCNTs are used with an aqueous mixture of THF, both the favorable phase equilibrium of THF and the high gas consumption of the carbon nanotubes can be obtained. Copyright © 2013 John Wiley & Sons, Ltd.

The effect of P and V contents on the microstructure and thermoelectric properties of Fe_2-xM_xO₃ (M: P and V; 0 ≤ x ≤ 0.01) is studied. Higher P and V contents result in increases of both the grain size and density, thus increasing the electrical conductivity. The absolute values of the Seebeck coefficients of the Fe_2-xP_xO₃ and Fe_2-xV_xO₃ increase with increasing P and V contents up to x = 0.0075 and 0.005, respectively, and then decrease with further increase of its concentration. The addition of a small amount of V (0.005) to Fe₂O₃ leads to a marked increase in both the electrical conductivity and Seebeck coefficient. This means that the introduction of a small amount of V is highly effective for improving the thermoelectric properties of Fe₂O₃. Copyright © 2013 John Wiley & Sons, Ltd.

The effect of P and V contents on the microstructure and thermoelectric properties of Fe_2-xM_xO₃(M: P and V; 0 ≤ x ≤ 0.01) is studied. Higher P and V contents result in increases of both the grain size and density, thus increasing the electrical conductivity. The introduction of a small amount of V is highly effective for improving the thermoelectric properties of Fe₂0_3.

Three different CO₂ separation technologies for production of synthetic natural gas (SNG) from biomass gasification – amine-based absorption, membrane-based separation and pressure swing adsorption – are investigated for their thermo-economic performance against the background of different possible future energy market scenarios. The studied scale of the SNG plant is a thermal input of 100 MW_th,LHV to the gasifier at a moisture content of 20 wt-% with a preceding drying step reducing the biomass' natural moisture content of 50 wt-%. Preparation of the CO₂-rich stream for carbon capture and storage is investigated for the amine-based absorption and the membrane-based separation technology alternatives. The resulting cold gas efficiency η_cg for the investigated process alternatives ranges between 0.65 and 0.695. The overall system efficiency η_sys ranges from 0.744 to 0.793, depending on both the separation technology and the background energy system. Amine-based absorption gives the highest cold gas efficiency whereas the potential for cogeneration of electricity from the process' excess heat is higher for membrane-based separation and pressure swing adsorption. The estimated specific production costs for SNG c_SNG for a process input of 90.3 MW_th,LHV at 50 wt-% moisture vary between 103–127 €₂₀₁₀/MWh_SNG. The corresponding production subsidy level c_subsidy needed to achieve end-user purchase price-parity with fossil natural gas is in the range of 56–78 €₂₀₁₀/MWh_SNG depending on both the energy market scenario and the CO₂ separation technology. Sensitivity analysis on the influence of changes in the total capital cost for the SNG plant on the production cost indicates a decrease of about 12% assuming a 30% reduction in total capital investment. Capture and storage of biogenic CO₂ – if included in the emission trading system – only becomes an option at higher CO₂ charges. This is due to increased investment costs but, in particular, due to the rather high costs for CO₂ transport and storage that have been assumed in this study. Copyright © 2013 John Wiley & Sons, Ltd.

This paper first presents a brief historical summary of the recent past and current status of refrigerants, and then proceeds to suggest a simple Second Law-based approach using the ideal vapor compression refrigeration cycle to estimate a refrigerant's performance potential. The resulting performance rankings are then supplemented by additional rankings of the exergy losses in the compressor and in the condenser. These methodologies are then applied to several refrigerants: three natural refrigerants (ammonia, propane, and isobutane), five conventional single-component halocarbon refrigerants, two conventional blends of halocarbon refrigerants, and three newer refrigerants (fluorinated propene isomers). Generally speaking, the lower pressure refrigerants have better COP and lesser volumetric cooling capacity than the higher pressure refrigerants; whereas, the lower pressure refrigerants have higher penalty factor (measure of condenser exergy losses) than the higher pressure refrigerants. The analyses presented in this paper suggest that to minimize a refrigeration system's overall impact on the environment, the choice of refrigerant should not necessarily be based on a single criterion but rather should be chosen based on the particular application. Copyright © 2013 John Wiley & Sons, Ltd.

1. An historical summary of the past/current status of refrigerants is presented.
2. Second Law-based approach to estimate a refrigerant's performance potential is presented.
3. Ranking methodologies for the exergy losses in the compressor and condenser are presented.
4. The Second Law-based methodologies are applied to several refrigerants (‘natural’, ‘traditional synthetic’, HFOs).

In a typical proton exchange membrane fuel cell (PEMFC), Nafion, i.e. a typical proton-exchange membrane, allows to permeate hydrogen and oxygen to the opposite electrode, resulting in unexpected parasitic reaction, and reduces open circuit potential (OCP) because of undesirable potential mixing. This paper investigates the influences of the anode flooding and fuel starvation on cell performance under mixed-potential conditions. A two-dimensional computational fluid dynamics model was formulated by considering direct oxidation reaction when hydrogen and oxygen molecules meet to account additional water generation in both anode and cathode catalyst layers. The present model was validated by comparing the simulated cell polarization with experimentally measured cell polarization. The authors have prepared membrane electrode assembly by the decal transfer method to precisely determine various parameters that dominate the electrode kinetics. Model validation was also conducted to clearly present the predictability of the model with different cell configurations, i.e. with and without microporous layers. Through the model, effect of the oxygen permeation coefficient of the Nafion membrane on the anode flooding was investigated. In addition, reverse-current generation was predicted with different anode saturations and oxygen permeation coefficients to provide a detailed explanation on their relationship. Copyright © 2013 John Wiley & Sons, Ltd.

A new zero CO₂ emission solid oxide fuel cell (SOFC) hybrid power system integrated with the oxygen ion transport membrane using CO₂ as sweep gas is proposed in this paper. The pure oxygen is picked up from the cathode outlet gas by the oxygen ion transport membrane with CO₂ as sweep gas; the oxy-fuel combustion mode in the afterburner of SOFC is employed. Because the combustion product gas only consists of CO₂ and steam, CO₂ is easily captured with lower energy consumption by the condensation of steam. With the aspen plus soft, this paper builds the simulation model of the overall SOFC hybrids system with CO₂ capture. The exergy loss distributions of the overall system are analyzed, and the effects of the key operation parameters on the overall system performance are also investigated. The research results show that the new system still has a high efficiency after CO₂ recovery. The efficiency of the new system is around 65.03%, only 1.25 percentage points lower than that of the traditional SOFC hybrid power system(66.28%)without CO₂ capture. The research achievements from this paper will provide the valuable reference for further study on zero CO₂ emission SOFC hybrid power system with higher efficiency. Copyright © 2013 John Wiley & Sons, Ltd.

This study aimed at presenting a model to simulate downdraft biomass gasification under steady-state or unsteady-state conditions. The model takes into account several processes that are relevant to the transformation of solid biomass into fuel gas, such as drying; devolatilization; oxidation; CO₂, H₂O, and H₂ reduction with char, pressure losses, solid and gas temperature, particle diameter, and bed void fraction evolution; and heat transfer by several mechanisms such as solid–gas convection, bed–wall convection, and radiation in the solid phase. Model validation is carried out by performing experiments in two lab-scale downdraft fixed bed reactors (unsteady-state conditions) and in a novel industrial pilot plant of 400 kW_th–100 kW_e (steady-state conditions). The capability of the model to predict the effect of several factors (reactor diameter, air superficial velocity, and particle size and biomass moisture) on key response variables (temperature field, maximum temperature inside the bed, flame front velocity, biomass consumption rate, and composition and calorific value of the producer gas) is evaluated. For most response variables, a good agreement between experimental and estimated values is attained, and the model is able to reproduce the trend of variation of the experimental results. In general terms, the process performance improves with higher reactor diameter and lesser air superficial velocity, particle size, and moisture content of biomass. The steady-state simulation appears to be a versatile tool for simulating different reactor configurations (preheating systems, variable geometry, and different materials). Copyright © 2013 John Wiley & Sons, Ltd.

The model developed agrees with the experiments under steady and unsteady conditions. The model is very sensitive to the kinetic of reaction rates. The unsteady model allows analyzing alternatives for process optimization. The steady-state simulation allows optimizing the gasifiers design.

Integrated pressurized water reactor (IPWR) usually be equipped with once-through steam generators (OTSGs). The OTSG has many advantages such as simple mechanical structure, smaller size, and higher heat transfer efficiency. It produces superheated steam but with less inventory in its secondary side. The steam pressure is easily affected by steam flow rate or feed water flow rate. This draws more attention to design advanced reactor control system. In this paper, a study has been carried out to analyze the thermal hydraulic performance of an advanced IPWR under steady-state and transient conditions by using a thermal hydraulic safety analysis code Relap5. An effective load-following control system is proposed. The steady-state operating characteristics of IPWR at different load conditions show that the average primary coolant temperature, steam pressure, and coolant mass flow rate are the most important control parameters. Pump frequency conversion strategy and OTSG grouping run strategy are used to study the transient operating characteristics of IPWR. Simulation results of the control system demonstrate its capability in regulating feedwater flow rate and reactor power to follow the change of steam flow rate. According to the results, the OTSG grouping run strategy is optimized to ensure the OTSG operates safely under low load conditions. Copyright © 2013 John Wiley & Sons, Ltd.

The mathematical model of an integrated reactor plant is developed to test the capability of reactor power control system for the rapid load-following characteristics using RELAP5 procedure. Simulation results of the control system demonstrate its capability in regulating the reactor power to match with the feed water flow rate automatically. According to the results, the OTSG grouping run strategy is optimized to ensure the safe operation of IPWR under low load conditions.

The article proposes a methodology to forecast the electric load for the 24 h of the following day based on support vector regression. The study considers 24 distinct models, one for each predicted hour, where each individual model is treated independently. Its objective is to find the optimal combination of support vector machine parameters that could generalize low forecasting errors, using simulated annealing as a metaheuristic. The adopted methodology is compared to concurrent methods based on neural networks when applied to a simulated load diagram (to illustrate a distribution feeder supplying a sample of 740 consumers). The results have proven its effectiveness with mean absolute percentage errors being less than 5% for testing samples. The study also focuses on evaluating the potential benefits of adopting load profiling information as input in support vector regression, giving a consistent proof of its importance. Copyright © 2013 John Wiley & Sons, Ltd.

• Support vector machines are applied to load forecasting purposes, integrating information derived from load profiling.
• Simulated annealing is used to identify the support vector machine parameters.
• A feature selection stage was performed to retain the most relevant inputs.

Thermoelectric devices are solid-state devices. Semiconductor thermoelectric cooling, based on the Peltier effect, has interesting capabilities compared to conventional cooling systems. In this work second law analysis of thermoelectric coolers has been done with the help of exergy destruction. In the first part, performance of single-stage thermoelectric coolers and multi stage thermoelectric coolers has been compared for same number of thermoelectric elements i.e. 50. The performance parameters considered to compare their performance are rate of refrigeration, coefficient of performance, second law efficiency and exergy destruction. In second part, multi stage thermoelectric coolers have been analyzed for three different combinations of number of elements in two stages of thermoelectric coolers. The result of the analysis shows that the performance of a multi stage thermoelectric cooler which has total 50 elements gives best performance when it has 30 elements in hotter side and 20 elements in colder side out of the three cases considered. The comparison of single-stage thermoelectric cooler and multistage thermoelectric cooler shows that for same number of elements rate of refrigeration (ROR) of single-stage thermoelectric cooler is much higher than that of multi stage thermoelectric cooler. The COP remains same for both of them but the peak value of cop is obtained at much lower value of current supplied in multi stage thermoelectric cooler. Exergy destruction has constant values in single stage as well as multi stage thermoelectric cooler when the two stages have equal number of elements but it decreases with increase in x. The result of comparison of multistage thermoelectric cooler for three values of x i.e. 0.5, 1, 1.5 shows that the COP, ROR and second law efficiency improve and exergy destruction degrades with increase in x and the best performance has been obtained for x = 1.5 out of the three values considered. Copyright © 2013 John Wiley & Sons, Ltd.

A double-stage thermoelectric cooler with 50 elements is compared with a single-stage Thermoelectric cooler. It was found that a former performs the best when it has 30 elements at hotter side and 20 elements at colder side.

This paper presents a simulation model for an energy hub consisting of natural gas (NG) turbines as the main sources of energy (including both electricity and heat) and two renewable energy sources—wind turbines (WTs) and photovoltaic (PV) solar cells. The hub also includes water electrolyzers for hydrogen production. The hydrogen serves as an energy storage medium that can be used in some transportation applications, or it can be mixed with the NG feed stream to improve the emission profile of the gas-turbine unit. The capacity of the designed hub is meant to simulate and replace the coal-fired Nanticoke Generating Station with a NG-fired power plant. Therefore, the aim of this work is to develop a simulated model that combines different energy generation technologies, which are evaluated in terms of the total energy produced, the cost per kWh of energy generated, and the amount of emissions produced. The proposed model investigates the benefits, both economic and environmental, the technological barriers, and the challenges of energy hubs by developing several scenarios. The simulation of these scenarios was done using General Algebraic Modeling System (GAMS®). Although the software is strongly known for its optimization capability, the mixed complementary problems solver makes it a strong tool for solving equilibrium problems. Excess energy produced during off-peak demand by WTs and PV solar cells was used to feed the electrolyzer to produce H₂ and O₂. The proposed approach shows that a significant reduction in energy cost and greenhouse gas emissions were achieved, in addition to the increased overall efficiency of the energy hub. Out of the examined three scenarios, Scenario C appeared to be the most feasible option for a combination of renewable and non-renewable technologies as it did not only produce hydrogen, but also provided electricity at relatively lower prices. Copyright © 2013 John Wiley & Sons, Ltd.

The works described a study on the preparation of LiBH₄ thin films by means of pulsed laser deposition. The results indicated that crystalline LiBH₄ films can be prepared from a LiB target under 70 Pa hydrogen atmosphere at ambient temperature. Compared with the former reports of LiBH₄, the hydrogen atmosphere and temperature were effectively reduced for the synthetical crystalline LiBH₄ films with amorphous Li₂B₁₂H₁₂. The mixture was successively dehydrided by two steps in dehydriding reaction, corresponding to the dehydriding amount of approximately 8 and 6 mass%. Compared with the former reports of LiBH₄ powder with no catalyzer, the primary dehydriding temperatures of the films was reduced. It will be easy to obtain the hydrogen from LiBH₄. This opens up new possibilities to study this important hydrogen storage material. Copyright © 2013 John Wiley & Sons, Ltd.

The integration of an aqua-ammonia inlet air-cooling scheme to a cooled gas turbine-based combined cycle has been analyzed. The heat energy of the exhaust gas prior to the exit of the heat recovery steam generator has been chosen to power the inlet air-cooling system. Dual pressure reheat heat recovery steam generator is chosen as the combined cycle configuration. Air film cooling has been adopted as the cooling technique for gas turbine blades. A parametric study of the effect of compressor–pressure ratio, compressor inlet temperature, turbine inlet temperature, ambient relative humidity, and ambient temperature on performance parameters of plants has been carried out. It has been observed that vapor absorption inlet air cooling improves the efficiency of gas turbine by upto 7.48% and specific work by more than 18%, respectively. However, on the adoption of this scheme for combined cycles, the plant efficiency has been observed to be adversely affected, although the addition of absorption inlet air cooling results in an increase in plant output by more than 7%. The optimum value of compressor inlet temperature for maximum specific work output has been observed to be 25 °C for the chosen set of conditions. Further reduction of compressor inlet temperature below this optimum value has been observed to adversely affect plant efficiency. Copyright © 2013 John Wiley & Sons, Ltd.

Addition of vapor absorption inlet air cooling improves both the plant-specific work and plant efficiency of gas turbine cycle. The addition of an absorption inlet air cooling could increase the optimum efficiency of gas turbine cycle by 7.48% and specific work by more than 18%. This enhancement in specific work increases to 8.39% at a turbine inlet temperature (TIT) of 1900 K for the 40 K drop in the value of compressor inlet temperature. This optimum value of r_p,c is found out to be 20 at a TIT of 1500 K and 28 at a TIT of 1800 K.

This article presents the influence of temperature and influent substrate composition on the produced biogas volume in an anaerobic co-digestion process. Four cases of anaerobic digestion were considered. Digestion of waste sludge only and anaerobic co-digestion of sludge mixed with solid waste in mesophilic (T = 35 °C) and thermophilic (T = 55 °C) phases. The obtained results show that thermophilic co-digestion gives the best results; although the temperature has an effect on biogas production, it remains however quite relative compared to the effect of solid waste. They confirm, surely, that the combined effect of temperature and solid waste improves considerably the biogas production rate (GPR). Changing conditions from mesophilic to thermophilic ones for waste sludge alone and for waste sludge mixed with solid waste results in an increase of the GPR from 0.18 to 0.39 m³/m³.d and from 0.29 to 0.96 m³/m³.d, respectively. Copyright © 2013 John Wiley & Sons, Ltd.

In this paper, a kind of proton exchange membrane fuel cell (PEMFC) bipolar plate based on plant vein is developed through biomimetic analogy theory. Fluent software is employed to test the performance characteristics of this newly designed bipolar plate. It is found from the numerical simulation results that the PEMFC performance will be influenced by the number and location of the biomimetic flow channel branches. The distribution pattern of branches has great impact on the outlet velocity. The more the branch number is, the more favorable for water removal. Finally, different operating parameters, such as temperature, pressure, relative humidity and stoichiometric ratio, are chosen based on the optimal flow channel configuration to improve PEMFC performance. Copyright © 2013 John Wiley & Sons, Ltd.

Establishing a better coordination between operating parameters and flow channel design is one of the most critical factors in achieving an optimum final performance of a fuel cell, since even a marginal change in any of the parameters can sharply affect the cell's performance. In this study, we report the use of three different acids, viz. sulphuric acid (H₂SO₄), formic acid (HCOOH) and phosphoric acid (H₃PO₄) as supporting electrolytes in combination with 2 M methanol fuel, wherein we demonstrated the effects of different combinations of acidic fuels and channel designs on the final cell performance. For this purpose, we made use of four different types of serpentine flow design. In the process, it was observed that an addition of 2 M concentrations of H₂SO₄ and H₃PO₄ enhanced the cell performance sharply in terms of current density, reaching values of 210 mAcm⁻² and 180 mAcm⁻², respectively, when analyzed at 0.2 V potential. This result was a considerable improvement over the current density value of 90 mAcm⁻² achieved while using only 2 M methanol analyzed at the same potential. Moreover, the open-circuit voltage showed a value of greater than 0.6 V for both fuel samples. With a flow channel length of 650 mm (A5SF2) and at an open ratio of 52%, we obtained maximum power values of 42 mWcm⁻² and 36 mWcm⁻² for fuels containing 2 M H₂SO₄ (M2S2) and 2 M H₃PO₄ (M2P2), respectively, when analyzed at 70°C. Copyright © 2013 John Wiley & Sons, Ltd.

The world consists of many countries having differences in many areas, ranging from size to economic level, from population to education, etc. Consequently, they are not going to convert to hydrogen-fueled transportation at the same time. Some will have the right conditions to convert to clean hydrogen transportation early, and other countries will have conditions which will result in a delay in conversion to hydrogen-fueled transportation. In order to find out which countries are the candidates for early conversion to hydrogen fueled transportation and which countries might convert to hydrogen-fueled transportation later, an analysis has been carried out covering almost all of the countries in the world. Results indicate that the countries with higher income per capita and smaller size could convert to hydrogen-fueled transportation earlier. Copyright © 2013 John Wiley & Sons, Ltd.

H₂ is generally used as the fuel in proton exchange membrane fuel cells (PEMFCs). However, H₂ produced from reformate gas usually contains a trace of CO, which may severely affect the fuel cell performance. With the adoption of domestic short side chain, low equivalent weight perfluorosulphonic acid (PFSA) membrane, a 100 W stack is built and evaluated at elevated temperature of 95 °C for the purpose of improving its CO tolerance. The stack is operated with 5 ppm, 10 ppm and 20 ppm CO/H₂, respectively; better performance is obtained as expected. Furthermore, a 5 kW PEMFC stack is prepared with home-made Ir–V/C and Pt/C as anode catalysts for the membrane electrode assemblies to compare their CO tolerance. Physical and electrochemical characterizations, such as transmission electron microscope and linear scan voltammogram are employed for catalyst investigation. The results demonstrate that the employment of domestic PFSA membrane enables the stack to be operated at 95 °C, which can improve the CO tolerance of all the anode catalysts. In addition, the effect of CO on cell polarization is insignificant at lower current densities. Under the same operating conditions, cells with Ir–V/C catalyst show better CO tolerance. Copyright © 2013 John Wiley & Sons, Ltd.

The CO tolerance of anode catalysts is improved at elevated operating temperatures, and the unit cells which adopt Ir–V/C as anode catalyst demonstrate superior performance compared with those with Pt/C catalyst at 95 °C in the presence of 5 ppm CO/H₂.

The aim of this work is to evaluate the performance of an innovative localized solar-assisted pen heating system for brooding using a 3D computational simulation model of the heated space. The warm air-curtained pen ensures acceptable temperature, air velocity, relative humidity, and air quality that meet the ventilation and heat requirements for a typical pen of 100 chicks as recommended by the American Society of Heating Refrigeration and Air Conditioning Engineers and American Society of Agricultural and Biological Engineers. The supply flow characteristics and the simulated velocity and temperature field of the curtained region were determined such that they meet the ventilation requirements and comfort criteria. Results show that air supplied at 40°C is capable of delivering the desired microenvironment at bird level while the heat input to the unit is 685 W when outdoor temperature is −5°C.

The system's energy performance was then analyzed using a prototype of 16 pens. The energy consumption of the new heating scheme consumed one third of the energy required by conventional non-localized system. Moreover, integrating the new design with a solar system utilizing parabolic concentrators provided 72% of the power load from solar energy during a winter flock operation and 100% during other seasons. Copyright © 2013 John Wiley & Sons, Ltd.

This work evaluates the performance of a localized solar-assisted pen heating system for brooding using a 3D computational model of the heated space. The warm air-curtained pen ensures acceptable temperature and air velocity that meet the heat requirements of 100 chicks. Results show that air supplied at 40°C is capable of delivering the desired microenvironment at bird level. The localized heating system for a prototype of 16 pens consumed one third of the energy required by conventional system.

Well-aligned zinc oxide (ZnO) nanorod arrays were formed on indium tin oxide (ITO)/glass substrates via a low-temperature hydrothermal growth of a sol–gel-derived seed layer. The seed layer was heat treated at 300 °C for 10 min prior to the hydrothermal growth using optimized conditions from our previous work to form well-aligned ZnO nanorod arrays. Hydrothermal growth time was varied for 4, 8, 12 and 24 h. Flat-top hexagonal ZnO nanorod arrays were obtained, and the length of the ZnO nanorods formed increased from approximately 150 nm after 4 h to approximately 2 µm after 24 h using a single reactive bath. X-ray diffraction patterns showed predominant ZnO peak at (002) plane for all the samples. Photoluminescence spectra of the ZnO nanorod arrays showed peaks at ultra-violet and green region, which indicated good crystalline crystal formation containing oxygen-related defects. Raman scattering results obtained showed strong band at 438 cm⁻¹ that correlated to E₂ non-polar hexagonal wurtzite phase. Dye-sensitized solar cells (DSSC) based on the well-aligned ZnO nanorod arrays were fabricated. The maximum conversion efficiency of 0.22% was achieved for the nanorods formed after a prolonged hydrothermal time of 24 h. The conversion efficiency of the DSSC increased with hydrothermal exposure time as longer ZnO nanorods provided larger surface for dye adsorption to generate more electrons. Improved crystallinity of the ZnO nanorods provided at prolonged hydrothermal time also contributed to the higher conversion efficiency as the electron transportation was enhanced. Copyright © 2013 John Wiley & Sons, Ltd.

Crystalline well-aligned zinc oxide (ZnO) nanorod arrays were formed by low-temperature hydrothermal growth at 80 °C on seeded ITO/glass in a single reactive bath. Effect of hydrothermal growth time was investigated. Prolonged hydrothermal growth time (up to 24 h) resulted in higher conversion efficiency as longer ZnO nanorods with improved crystallinity were formed.

This investigation is persuaded for the first and second law analyses of a new solar-driven triple-effect refrigeration cycle using Duratherm 600 oil (Duratherm Extended Life Fluid, NY, USA) as the heat transfer fluid is performed. The proposed cycle is an integration of ejector, absorption, and cascaded refrigeration cycles that could produce refrigeration output of different magnitude at different temperature simultaneously. Both exergy destruction and losses in each component and hence in the overall system are determined to identify the causes and locations of the thermodynamic imperfection. The effects of some influenced parameters such as hot oil outlet temperature, refrigerant turbine inlet pressure, and the evaporator temperature of ejector and cascaded refrigeration cycle have been observed on the first and second law performances. It is found that maximum irreversibility occurs in central receiver as 52.5% and the second largest irreversibility of 25% occurs in heliostat field. The second law efficiency of the solar driven triple effect refrigeration cycle is 2%, which is much lower than its first law efficiency of 11.5%. Analysis clearly shows that performance evaluation based on the first law analysis is inadequate and hence, more meaningful evaluation must be included in the second law analysis. Copyright © 2013 John Wiley & Sons, Ltd.

The paper focuses on the use of oxygen and steam as the gasification agents in the thermochemical conversion of biomass to produce hydrogen rich syngas, using a downdraft reactor configuration.

Performance of the reactor is evaluated for different equivalence ratios (ER), steam to biomass ratios (SBR) and moisture content in the fuel. The results are compared and evaluated with chemical equilibrium analysis and reaction kinetics along with the results available in the literature. Parametric study suggests that, with increase in SBR, hydrogen fraction in the syngas increases but necessitates an increase in the ER to maintain reactor temperature toward stable operating conditions. SBR is varied from 0.75 to 2.7 and ER from 0.18 to 0.3. The peak hydrogen yield is found to be 104 g/kg of biomass at SBR of 2.7. Further, significant enhancement in H₂ yield and H₂ to CO ratio is observed at higher SBR (SBR = 1.5–2.7) compared with lower range SBR (SBR = 0.75–1.5).

Experiments were conducted using wet wood chips to induce moisture into the reacting system and compare the performance with dry wood with steam. The results clearly indicate the both hydrogen generation and the gasification efficiency (η_g) are better in the latter case. With the increase in SBR, gasification efficiency (η_g) and lower heating value (LHV) tend to reduce. Gasification efficiency of 85.8% is reported with LHV of 8.9 MJ Nm⁻³ at SBR of 0.75 compared with 69.5% efficiency at SBR of 2.5 and lower LHV of 7.4 at MJ Nm⁻³ at SBR of 2.7. These are argued on the basis of the energy required for steam generation and the extent of steam consumption during the reaction, which translates subsequently in the LHV of syngas. From the analysis of the results, it is evident that reaction kinetics plays a crucial role in the conversion process.

The study also presents the importance of reaction kinetics, which controls the overall performance related to efficiency, H₂ yield, H₂ to CO fraction and LHV of syngas, and their dependence on the process parameters SBR and ER. Copyright © 2013 John Wiley & Sons, Ltd.

In recent years, Integrated Gasification Combined Cycle Technology (IGCC) has been gaining popularity for use in clean coal power operations with carbon capture and sequestration. Great efforts have been continuously spent on investigating ways to improve the efficiency and further reduce the greenhouse gas emissions of such plants. This study focuses on investigating two approaches to achieve these goals. First, replace the traditional subcritical Rankine cycle portion of the overall plant with a supercritical steam cycle. Second, add biomass as co-feedstock to reduce carbon footprint as well as SO_x and NO_x emissions. In fact, plants that use biomass alone can be carbon neutral and even become carbon negative if CO₂ is captured.

Due to a limited supply of feedstock, biomass plants are usually small, which results in higher capital and production costs. In addition, biomass can only be obtained at specific times in the year, resulting in fairly low capacity factors. Considering these challenges, it is more economically attractive and less technically challenging to co-gasify biomass wastes with coal. The results show that for supercritical IGCC, the net efficiency increases with increased biomass in all cases. For both subcritical and supercritical cases, the efficiency increases from 0% to 10% (wt.) biomass and decreases thereafter. However, the efficiency of the blended cases always remains higher than that of the pure-coal baseline cases. The emissions (NO_x, SO_x, and effective CO₂) and the capital costs decrease as biomass ratio (BMR) increases, but the cost of electricity (CoE) increases with BMR due to the high cost of the biomass used.

Finally, implementing a supercritical steam cycle is shown to increase the net plant output power by 13% and the thermal efficiency by about 1.6 percentage points (or 4.56%) with a 6.7% reduction in capital cost, and a 3.5% decrease in CoE. Copyright © 2013 John Wiley & Sons, Ltd.

The influences of the performance parameters and the heat transfer characteristics of the absorption heat pump using ammonia–water mixture are theoretically carried out. There is a pronounced effect of the ammonia concentration ξ after rectifier on the temperature glides that has been investigated. At ξ = 0.9000 and saturation pressures of 75 and 0.5 bar, the temperature glides are 64.4°C and 81.21°C, respectively, whereas these glides are 0°C and 16.1°C at ξ = 0.9999 and at the same pressures. This mixture property considerably affects the absorption system performance and the design of the rectifier as well as other absorption components. A correlation of the Nusselt number, Nu, is developed and compared with some published work in the literature for plate type heat exchanger. The effects of ammonia concentration ξ, mass fraction spread Δξ, specific solution circulation ratio f, and pressure ratio R_p on the refrigerant mass flow rate, the pressure drop, and the heat transfer coefficients during the condensation, the evaporation, and the absorption processes are investigated. It was found that increasing ammonia mass fraction spread Δξ results in both specific circulation ratio f and R_p that have insignificant effects on the refrigerant mass flow rate. Mounting Δξ at constant f reduces the pressure drop gradually and subsequently starts to increase as Δξ escalates. The ammonia concentration ξ has insignificant effect on the evaporation heat transfer coefficient but has a little effect on the condensation and the absorber heat transfer coefficients. The ammonia mass fraction spread Δξ and f have considerable effects on the heat transfer coefficient for different absorption heat pump components. R_p has a pronounced effect on the evaporation heat transfer coefficient, although it has a slight effect on the condensation and the absorber heat transfer coefficients. The effect of R_p on the heat transfer coefficient may be eliminated in the absorber for Δξ > 0.18. Copyright © 2013 John Wiley & Sons, Ltd.

In this paper, a simple and fast method based on extreme learning machine (ELM) for the estimation of solar radiation in Turkey was presented. To design the ELM model, satellite data of the National Oceanic and Atmospheric Administration advanced very high-resolution radiometer from 20 locations spread over Turkey were used. The satellite-based land surface temperature, altitude, latitude, longitude, month, and city were applied as input to the ELM, and the output variable is the solar radiation. To show the applicability of the ELM model, a performance comparison in terms of the estimation capability and the learning speed was made between the ELM model and conventional artificial neural network (ANN) model with backpropagation. The comparison results showed that the ELM model gave better estimation than the ANN model for the overall test locations. Moreover, the ELM model was about 23.5 times faster than the ANN model. The method could be used by researchers or scientists to design high-efficiency solar devices such as solar power plant and photovoltaic cell. Copyright © 2013 John Wiley & Sons, Ltd.

The basis of this study was to investigate the feasibility of using ELM to model the non-linear relationship between satellite-based input parameters and solar radiation.The comparison results showed that the ELM model gave better estimation than the ANN model for the overall test locations. Moreover, the ELM model was about 23.5 times faster than the ANN model. The method could be used by researchers or scientists to design high-efficiency solar devices such as solar power plant and photovoltaic cell.

This research answers the question of how to measure the sustainability of a renewable energy systems (RESs) as a physical parameter. Renewable energy is considered as a solution for mitigating the energy crisis, climate change and environmental pollution; however, an important problem of its application is that it is very difficult to evaluate the sustainability of RESs. This study develops a general sustainability indicator which is a tool to evaluate sustainability of RESs precisely and comprehensively. Based on the Triple Bottom Line approach, 11 Basic Sustainability Indicators with different dimensions and various units are selected from environmental, economic and social sustainability assessment criteria. In order to deal with the uncertainties in the definition and the assessment of sustainability, the grey regression analysis method is employed to quantify the basic indicators and to aggregate them into the general indicator. In addition, for explaining application of the general indicator, the cases of four RESs in hot-arid Australia are presented. In the case study, the grey indicator is used to assess the sustainability of four systems with different combinations of grid, solar photovoltaic and wind renewable energy. The final results are compared with the general indicator based on fuzzy sets theory developed in previous studies. It is found that for the case of Australian system, the grey sustainability indicator has a good linear correlation to the fuzzy indicator results. The grey indicator is an effective way to assess the sustainability of RESs and provides a good tool for designers, users, decision makers and researchers. Copyright © 2013 John Wiley & Sons, Ltd.

A thermoeconomic analysis of a ground-source heat pump (GSHP) system with a vertical or horizontal ground heat exchanger, a type of heat delivery system, was performed using the modified productive structure analysis method. In this analysis, the unit cost of geothermal heat delivered to a room using GSHP system was estimated. The unit cost of heat delivered was calculated to be $0.063/kWh for input of electricity with a unit cost of $0.140/kWh for a GSHP with a coefficient of performance (COP) of 3.27. Exergy destruction and monetary losses due to the irreversibility that occurs at each component of the system were also estimated. The unit cost of heat was found to be inversely proportional to the COP of the heat pump and proportional to the electricity input. The greatest monetary loss occurs in the geothermal heat exchanger in which considerable mass of brine flows in long pipes and in the fan-coil unit which features a complex configuration of pipes in the air passages, respectively. Copyright © 2013 John Wiley & Sons, Ltd.

The study systematically analyzes the performance of micro direct methanol fuel cell (μDMFC) with different flow fields. A two-phase three-dimensional model is developed to evaluate the mass transport accurately. The transport of methanol and air, the pressure distribution, the anode saturation, and the methanol crossover are numerically observed, the under-rib convection is also investigated numerically. The flow fields with an active area of 0.64 cm² are fabricated on silicon wafers by micro electromechanical system technology. Performance of μDMFCs with different flow fields is sorted as: double-serpentine flow field (DSFF) > single-serpentine flow field (SSFF) > triple-serpentine flow field (TSFF), and the dynamic test results indicate the cell with DSFF takes the shortest time to reach a stable power output when compared with other cells. Copyright © 2013 John Wiley & Sons, Ltd.

Parameters and boundary conditions (Table 1 and 2) were used in the 3D μDMFC to simulate mass transport and cell performance on μDMFC with different anode flow fields, and the cell was fabricated according to the Geometry of Table 3 to verify the simulation results.

The development of the hydrogen economy is hampered by many issues connected with production, storage, distribution, and end-use. Although the hydrogen storage problem is particularly difficult, there are several attractive solutions under investigation, and chemical hydrogen storage (involving hydrogen-rich materials) has shown much promising properties. The boron-based materials are typical examples. They have high hydrogen densities, with up to four reactive B − H bonds. Most of the works have focused on dehydrogenation by hydrolysis or thermolysis so that it takes place in high extent in mild conditions. The first materials studied have been lithium borohydride, sodium borohydride, and ammonia borane. However, their development has been hindered by technical issues such as very high dehydrogenation temperatures, incomplete reaction, and purity of the produced hydrogen. To get round such problems, new materials have been proposed since the mid-2000s. Interestingly, those materials present attractive attributes, but also drawbacks. This is illustrated in the present review. We believe that boron-based hydrides have a significant potential in chemical hydrogen storage, but their implementation depends on the recyclability of the solid by-products; this seems to be the key factor. Copyright © 2013 John Wiley & Sons, Ltd.

Boron-based materials have shown a reviving interest over the past two decades in materials chemistry. Indeed, they are very promising as chemical hydrogen storage materials. The recent progresses have notably shown their attractive properties. This is surveyed herein.

A methodology for optimal control of the polymer electrolyte membrane fuel cell (PEMFC) with multiple criteria is presented here. In this regard, thermoelectric objectives and thermoeconomic objective are considered, simultaneously. The proposed fuel cell is a 1200 W Ballard PEMFC namely Nexa™ power module. The net power density and exergetic efficiency of the PEMFC are maximized, and the unit cost of the generated power is minimized in a multi-objective optimization procedure using the NSGA-II (non-dominated sorting genetic algorithm). Operating temperature and pressure, air stoichiometric coefficient at the cathode and the current density are considered as controlling parameters in order to acquire optimal performance of the PEMFC. A set of optimal solution namely the Pareto frontier is obtained, and a final optimal solution is selected from available solutions located on the Pareto frontier using the fuzzy decision-making process based on the Bellman–Zadeh approach. Results are compared with corresponding results obtained previously in single objective optimization scenarios. It has been shown that the optimal operating condition obtained based on the multiple criteria approach has least deviation from the ideal features of the fuel cell in comparison to the corresponding optimal solution obtained in conventional single-objective optimization approaches. Copyright © 2013 John Wiley & Sons, Ltd.

The splitting of water in the presence of ordinary and nano TiO₂ was carried out using hydrocarbon as a dual agent and solar energy as a light source for these experiments. The hydrogen gas evolved was tested and measured using downward displacement of water. The observed results show that more hydrogen was evolved when nano TiO₂ was used as catalyst due to the larger surface area of the nano material. The splitting of sea water yields more hydrogen compared with ordinary water due to the presence of electron donating sodium ions in water. The added hydrocarbon plays a dual role as electron donor and as a trapping agent, which enhances the production of hydrogen to a greater extent compared with the regular donors such as olefin. Copyright © 2013 John Wiley & Sons, Ltd.

A compression–absorption cascade system for refrigeration is simulated with different working fluids. LiBr/H₂O is used in the absorption cycle and ammonium, R134a and carbon dioxide are evaluated in the compression cycle. First and second laws of thermodynamic analysis were analyzed with the aim of finding the best working fluid performance and appropriate operation parameters. Coefficient of performance, exergetic efficiency, irreversibility of the main components of the system, total irreversibility of the system and improvement potential were estimated for each one of the systems proposed. The results showed that the highest irreversibilities occurred in the cascade heat exchanger using carbon dioxide or ammonium, but this value decreased by using R134a. The highest value of coefficient of performance is observed by the R134a–LiBr/H₂O system when the minimum of irreversibility in the absorber and generator are reached within a range of generator temperature from 339 to 345 K. Copyright © 2013 John Wiley & Sons, Ltd.

In this paper, a method that utilizes CO₂ vapor compression thermodynamic cycle to recover low-temperature heat from exhausted water steam of fossil fuel thermal power plants is reported. Experimental investigation was carried out to study the characteristics of low-temperature heat recovery by liquid CO₂ evaporation process from vacuum exhausted steam condensation occurring at the turbine exit. Furthermore, measured heat recovery performances over one whole year are presented and discussed. Experimental results show that the present heat recovery process by CO₂ vapor compression cycle is able to operate stably. The yearly averaged water temperature at the CO₂ condenser outlet was measured at 87.5 °C with a COP value above 5.0. This high energy efficiency ratio is found to be mainly due to two factors: the transcritical CO₂ vapor compression and steam condensation phase change occurring on the CO₂ evaporator. The findings from this paper provide helpful guidelines for low-temperature heat recovery system design and improving fossil fuel utilization efficiency. Copyright © 2013 John Wiley & Sons, Ltd.

Turbine inlet cooling (TIC) is a common technology used to increase combustion turbine power output and efficiency. The use of mechanical or absorption chillers for TIC allows for more air cooling than evaporative methods and also imposes a significant parasitic load to the turbine. Thermal energy storage (TES) can be used to shift this load to off-peak hours. Use of thermal storage increases the flexibility of turbine power output, which benefits from the application of optimization tools. This paper explores the effect of combining TIC with TES to enhance the performance of a district cooling system that includes a gas turbine for power generation. The work illustrates how the system's performance can be enhanced using optimization. Application of multi-period optimization to the system that includes TES brings significant operational cost savings when compared with a system without thermal storage. It is also shown how TES provides demand-side energy management in the district cooling loop and supply-side management through the use of TIC. In addition to the optimization study, a thorough literature review is included that describes the current body of work on combining TIC with TES. Copyright © 2013 John Wiley & Sons, Ltd.

This paper explores the effect of combining turbine inlet cooling with thermal energy storage to enhance the performance of a district energy system that includes a gas turbine for power generation. Application of multi-period optimization to this system brings significant operational cost savings, reducing net costs by up to 79%. The balance between energy and cost minimization is also investigated.

This study uses both experiments and simulations to investigate the effects of polybenzimidazole (PBI) loading design in the catalyst layer (CL) on the performance of a high-temperature proton exchange membrane fuel cell (HTPEMFC). The performance of a self-made PBI-based HTPEMFC with various PBI loading in the CL are experimentally measured. A two-dimensional (2D) simulation model is also developed to numerically predict the characteristics of the cell. The CL with single-layer PBI loadings of 5, 10, 20, and 30 wt%; two-layer PBI loadings of 5–30 wt%, and three-layer PBI loadings of 5–10–20 wt% are considered. According to the experimental measurements, the performance of the PEMFC with the two-layer CL design is similar to that of the PEMFC with the single-layer of 10 wt% PBI loading design, superior to that of the single-layer 20 wt% PBI loading design, and inferior to that of the single-layer 5 wt% loading design. The measured current density versus voltage curve for the PEMFC with the three-layer loading design matches that of the single-layer 5 wt% PBI loading. The present model also captures these characteristics. Both the experimentally measured and the model predicted results demonstrate that the multilayer PBI loading design in the CL can offer the advantages of both lower and higher PBI loading, with the lower loading near the gas diffusion layer and the higher loading located near the membrane. Copyright © 2013 John Wiley & Sons, Ltd.

Parabolic trough solar collector usually consists of a parabolic solar energy concentrator, which reflects solar energy into an absorber. The absorber is a tube, painted with solar radiation absorbing material, located at the focal length of the concentrator, usually covered with a totally or partially vacuumed glass tube to minimize the heat losses. Typically, the concentration ratio ranges from 30 to 80, depending on the radius of the parabolic solar energy concentrator. The working fluid can reach a temperature up to 400°C, depending on the concentration ratio, solar intensity, working fluid flow rate and other parameters. Hence, such collectors are an ideal device for power generation and/or water desalination applications. However, as the length of the collector increases and/or the fluid flow rate decreases, the rate of heat losses increases. The length of the collector may reach a point that heat gain becomes equal to the heat losses; therefore, additional length will be passive. The current work introduces an analysis for the mentioned collector for single and double glass tubes. The main objectives of this work are to understand the thermal performance of the collector and identify the heat losses from the collector. The working fluid, tube and glass temperature's variation along the collector is calculated, and variations of the heat losses along the heated tube are estimated. It should be mentioned that the working fluid may experience a phase change as it flows through the tube. Hence, the heat transfer correlation for each phase is different and depends on the void fraction and flow characteristics. However, as a first approximation, the effect of phase change is neglected. Copyright © 2013 John Wiley & Sons, Ltd.

Pinch point analysis can be adapted so as to assist in the early stages of designing the Organic Rankine Cycle (ORC) systems. Typically used in determining the working parameters of heat exchangers, it can be employed to improve the heat fitting between the source of heat and the working fluids of the ORC system. To attain the parametric match, an algorithm was built enabling quick estimation of the possible heat reception by the specific working fluid. In effect, it is now possible to attain quick estimation of the upper limits of the electrical power output and the overall conversion efficiency. This paper outlines the developed algorithm and the range of its possible applications and presents the results of sample calculations. Copyright © 2013 John Wiley & Sons, Ltd.

Alcoholysis of sodium borohydride offers advantages due to reduction in number of steps for recycling of sodium borohydride, elimination of freezing problems that are associated with the use of water, fast generation of hydrogen, etc. Methanol was used to liberate hydrogen from sodium borohydride. The influence of the amount of solvent, substrate concentration, temperature and catalyst on the kinetics of alcoholysis reaction in non-stabilized sodium borohydride has been examined in the present study. The reaction was found to be first order with respect to substrate concentration and zero order with respect to solvent concentration. Effect of soluble metal salts, metal powder and metal boride as catalysts on hydrogen generation rate has also been investigated. It was found that NiCl₂, Ni₂B and RuCl₃ were effective catalysts and hydrogen generation proceeds with high efficiency in the presence of these catalysts. Copyright © 2013 John Wiley & Sons, Ltd.

Summary

1. Hydrogen generation studied by alcoholysis of NaBH₄ with methanol
2. Hydrogen generation occurs even at 0 °C
3. Activation energy for alcoholysis is 26KJ/mole
4. High efficiency was obtained with NiCl₂, Ni₂B and RuCl₃ catalysts

This paper presents the thermodynamic assessment of biomass steam gasification via interconnected fluidized beds (IFB) system. The performance examined included the composition, yield and higher heating value (HHV) of dry syngas, and exergy efficiencies of the process. Two exergy efficiencies were calculated for the cases with and without heat recovery, respectively. The effects of steam-to-biomass ratio (S/B), gasification temperature, and pressure on the thermodynamic performances were investigated based on a modified modeling of the IFB system. The results showed that at given gasification temperature and pressure, the exergy efficiencies and dry syngas yield reached the maximums when S/B was at the corresponding carbon boundary point (S/B_CBP). The HHV of the dry syngas continuously decreased with the increase of S/B. Moreover, the exergy efficiency with heat recovery was averagely a dozen percentage points higher than that without heat recovery. Under atmospheric conditions, lower gasification temperature favored the yield and HHV of dry syngas at various S/B. In addition, it also favored the exergy efficiencies of the process when S/B is approximately larger than 0.75. Under pressurized conditions, higher gasification pressure favored both the yield and HHV of dry syngas, as well as the exergy efficiencies at different S/B. Copyright © 2012 John Wiley & Sons, Ltd.

Effects of gasification pressure (p_G) and steam-to-biomass ratio (S/B) on exergy efficiencies of biomass gasification via interconnected fluidized beds without (ψ_-) and with (ψ₊) heat recovery at gasification temperature of 700 °C (p_G: ■: 1 bar, ○: 10 bar, ▲: 20 bar).

The rich-hydrogen generation from ethanol steam reforming over NiZr, which is used as an anode material in solid oxide fuel cells, -loaded MCM-48 (NiZr/MCM-48) catalyst was investigated in this study. We used an impregnation approach to synthesize an MCM-48 (70.0 wt-%) support loaded with bimetallic NiZr (30.0-wt%, Ni:Zr atomic ratio = 4:6, 5:5, and 6:4), and the prepared catalysts were applied to the steam-reforming reactions of ethanol. These three bimetallic NiZr/MCM-48 catalysts exhibited significantly higher reforming reactivity than the mono-metal, Ni-loaded MCM-48 (Ni/MCM-48) catalyst. The hydrogen production was started from 350°C over the three NiZr/MCM-48 catalysts, compared to above 550°C over the Ni/MCM-48 catalyst. The catalytic performance was affected by the Zr content. The H₂ production and ethanol conversion were maximized at 85% and 95%, respectively, over Ni₄Zr₆/MCM-48 at 750°C for 1 h at CH₃CH₂OH:H₂O = 1:1 and a gas hourly space velocity of 4000 h^-1. This high performance was maintained for up to 60 h. Copyright © 2013 John Wiley & Sons, Ltd.

A carbon lump was found after ethanol steam reforming over the four experimental catalysts and was observed by TEM. At a certain time after the beginning of the reaction, e.g., 10 h at 750^oC, the carbons were deposited on the surface of the catalyst. In general, CO₂ and ethanol could be converted into carbon nanotubes (or filaments) on the carbon deposited on the catalyst surface. Interestingly, many carbon lumps were generated in the catalysts with high Ni content; otherwise, the carbon nanotubes increased with increasing Zr content, particularly in Ni₄Zr₆/MCM-48.

Bio-hydrogen renowned as a future potential hydrogen source and studies were devoted in developing the efficient way to obtain the hydrogen. Biomass gasification of Azadirachta excelsa wood was carried out with addition of naturally derived CaO catalyst using temperature-programmed gasification (TPG) technique. The reaction (TPG) was performed at 50–1000°C in 5% O₂/He with flow rate 10 ml/min, and the product gas evolution (H₂, CH₄, CO and CO₂) was detected by online mass spectrometer. The waste eggshell was chosen as a natural source of CaO, and the effect of catalyst loading was investigated in this study. All the fresh and used catalysts were characterized, and the physicochemical changes of the eggshell were observed through scanning electron microscopy, X-ray fluorescence and X-ray diffraction techniques. Hydrogen yield were increased along with the catalyst loading (20%, 40% and 60%) from 57 to 73%, respectively, compared to the reaction without catalyst. The additions of waste eggshell enhanced the catalytic activity and suppressed CO₂ production through CaO absorption property which induced the water gas shift reaction that promotes H₂ production at lower temperature. Copyright © 2013 John Wiley & Sons, Ltd.

One serious challenge of energy systems design, wind turbines in particular, is the need to match the system operation to the variable load. This is so because system efficiency drops at off-design load. One strategy to address this challenge for wind turbine blades and obtain a more consistent efficiency over a wide load range, is varying the blade geometry. Predictable morphing of wind turbine blade in reaction to wind load conditions has been introduced recently. The concept, derived from fish locomotion, also has similarities to spoilers and ailerons, known to reduce flow separation and improve performance using passive changes in blade geometry. In this work, we employ a fully coupled technique on CFD and FEM models to introduce continuous morphing to desired and predetermined blade design geometry, the NACA 4412 profile, which is commonly used in wind turbine applications. Then, we assess the aerodynamic behavior of a morphing wind turbine airfoil using a two-dimensional computation. The work is focused on assessing aerodynamic forces based on trailing edge deflection, wind speed, and material elasticity, that is, Young's modulus. The computational results suggest that the morphing blade has superior part-load efficiency over the rigid NACA blade. Copyright © 2013 John Wiley & Sons, Ltd.

The fluid-structure interaction of a chord-wise morphing airfoil for wind turbine energy conversion was investigated. The morphing blade performed better than the rigid blade at part-load. For over load, the performance of a morphed blade was worse than that of a rigid blade. Blades which exhibited the best performance at part load exhibited the worst performance at over load. The morphing of a blade does not prevent it from flow separation at over load conditions.

An energy analysis of three typical solid oxide fuel cell (SOFC) power systems fed by methane is carried out with detailed thermodynamic model. Simple SOFC system, hybrid SOFC-gas turbine (GT) power system, and SOFC-GT-steam turbine (ST) power system are compared. The influences of air ratio and operative pressure on the performance of SOFC power systems are investigated. The net system electric efficiency and cogeneration efficiency of these power systems are given by the calculation model. The results show that internal reforming SOFC power system can achieve an electrical efficiency of more than 49% and a system cogeneration efficiency including waste heat recovery of 77%. For SOFC-GT system, the electrical efficiency and cogeneration efficiency are 61% and 80%, respectively. Although SOFC-GT-ST system is more complicated and has high investment costs, the electrical efficiency of it is close to that of SOFC-GT system. Copyright © 2013 John Wiley & Sons, Ltd.

The internal reforming SOFC power system can achieve an electrical efficiency of more than 49% and a system cogeneration efficiency including waste heat recovery of 77%. For SOFC-gas turbine (GT) system, the electrical efficiency and cogeneration efficiency are 61% and 80%, respectively. Although SOFC-GT-steam turbine system is more complicated and has high investment costs, the electrical efficiency of it is close to that of SOFC-GT system.

The standard working pairs for absorption chillers, ammonia/water and water/lithium bromide show problematic behaviours like crystallisation and corrosiveness. Because of their convenient solving properties and their low vapour pressure, ionic liquids are a new promising class of sorbents for absorption cooling purposes. In this study, the working pairs water/1,3-dimethylimidazolium dimethylphosphate ([MMIM][DMP]) and water/1-ethyl-3-methylimidazolium dimethylphosphate ([EMIM][DMP]) are implemented in AspenPlus. The performance of a single effect cycle with these pairs is simulated and compared to results of a cycle with water/LiBr. For [EMIM][DMP] a coefficient of performance (COP) comparable to that of LiBr or even higher (up to 0.85) is found. [MMIM][DMP] shows a smaller maximum COP but a largely wider operating temperature range than LiBr. Results are compared with those of other groups, discrepancies discussed and improvements suggested. Copyright © 2013 John Wiley & Sons, Ltd.

The working pairs water/1,3-dimethylimidazolium dimethylphosphate ([MMIM][DMP]) and water/1-ethyl-3-methylimidazolium dimethylphosphate ([EMIM][DMP]) are implemented in AspenPlus. The performance of a single effect cycle is simulated and compared to results of a cycle with water/LiBr. For [EMIM][DMP], a coefficient of performance comparable to that of LiBr or even higher (up to 0.85) is found, whereas [MMIM][DMP] shows a large wider operating temperature range.

This paper performed a comparative analysis of organic Rankine cycle (ORC) using different working fluids, in order to recover waste heat from a solid oxide fuel cell-gas turbine hybrid power cycle. Depending on operating parameters, criteria for the choice of the working fluid were identified. Results reveal that due to a significant temperature glide of the exhaust gas, the actual ORC cycle thermal efficiency strongly depends on the turbine inlet temperature, exhaust gas temperature, and fluid's critical point temperature. When exhaust gas temperature varies in the range of 500 K to 600 K, R123 is preferred among the nine dry typical organic fluids because of the highest and most stabilized mean thermal efficiency under wide operating conditions and its reasonable condensing pressure and turbine outlet specific volume, which in turn results in a feasible ORC cycle for practical concerns. Copyright © 2012 John Wiley & Sons, Ltd.

Higher demand for energy consumption and importance of environmental issues has encouraged researchers and policy makers to consider renewable energies more seriously. Geothermal resources are a green energy source that can make a considerable contribution in some countries. Japan has the third ranking geothermal energy potential, and its geothermal electricity production is currently eighth in the world. Since the nature of geothermal resources dictates its method of utilization, it is important to categorize available resources. There is no consensus on classification of geothermal resources. Most scientists, from geologist to engineers, agree on the term temperature. However, temperature or enthalpy alone cannot describe the nature of fluids; they can have same temperature with different phases, such as saturated water or saturated steam. Using exergy for resource classification benefits their comparison, according to their ability to do work. In this paper, exergetic classification of geothermal resources was applied to 18 under-operating geothermal power plants in Japan. Six geothermal fields have high exergy resources according to their SExI values in excess of 0.5. The remaining geothermal fields in Japan are classified in the medium resources zone. Classification results can be used by decision makers as a reference for future geothermal development. Copyright © 2012 John Wiley & Sons, Ltd.

To meet next generation energy needs such as wind- and solar-generated electricity, enhanced oil recovery (EOR), CO₂ capture and storage (CCS), and biofuels, the US will have to construct tens to hundreds of thousands of kilometers of new transmission lines and pipelines. Energy network models are central to optimizing these energy resources, including how best to produce, transport, and deliver energy-related products such as oil, natural gas, electricity, and CO₂. Consequently, understanding how to model new transmission lines and pipelines is central to this process. However, current energy models use simplifying assumptions for deploying pipelines and transmission lines, leading to the design of more costly and inefficient energy networks. In this paper, we introduce a two-stage optimization approach for modeling CCS infrastructure. We show how CO₂ pipelines with discrete capacities can be ‘linearized’ without loss of information and accuracy, therefore allowing necessarily complex energy models to be solved. We demonstrate the new approach by designing a CCS network that collects large volumes of anthropogenic CO₂ (up to 45 million tonnes of CO₂ per year) from ethylene production facilities and delivers the CO₂ to depleted oil fields to stimulate recovery through EOR. Utilization of anthropogenic CO₂ has great potential to jumpstart commercial-scale CCS while simultaneously reducing the carbon footprint of domestic oil production. Model outputs illustrate the engineering challenge and spatial extent of CCS infrastructure, as well as the costs (or profits) of deploying CCS technology. We show that the new linearized approach is able to offer insights that other network approaches cannot reveal and how the approach can change how we develop future energy systems including transporting massive volumes of shale gas and biofuels as well as electricity transmission for wind and solar energy. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.

Next generation energy needs-such as unconventional gas, biofuels, wind and solar energy, and CO₂ capture and storage (CCS) will require tens to hundreds of thousands of kilometers of new transmission lines and pipelines. We present a new two-stage optimization approach for modeling large-scale energy networks. We demonstrate the approach using CCS infrastructure. Specifically, we design infrastructure to capture anthropogenic CO₂ from ethylene production, transport the CO₂ in a dedicated pipeline network, and store the CO₂ in the subsurface while stimulating oil production through enhanced oil recovery.

We compare battery performance simulations from a commercial lithium-ion battery modeling software package against manufacturer performance specifications and laboratory tests to assess model validity. A set of commercially manufactured spiral wound lithium-ion cells were electrochemically tested and then disassembled and physically characterized. The Battery Design Studio^® (BDS) software was then used to create a mathematical model of each battery, and discharge simulations at constant C-rates ranging from C/5 to 2C were compared against laboratory tests and manufacturer performance specifications. Results indicate that BDS predictions of total energy delivered under our constant C-rate battery discharge tests are within 6.5% of laboratory measurements for a full discharge and within 2.8% when a 60% state of charge window is considered. Average discrepancy is substantially lower. In all cases, the discrepancy in simulated vs. manufacturer specifications or laboratory results of energy and capacity delivered was comparable to the discrepancy between manufacturer specifications and laboratory results. Results suggest that BDS can provide sufficient accuracy in discharge performance simulations for many applications. Copyright © 2012 John Wiley & Sons, Ltd.

We compare battery performance simulations from a commercial lithium-ion battery modeling software package, Battery Design Studio^® (BDS), against manufacturer performance specifications and laboratory tests to assess model validity. This was done using a set of commercially manufactured spiral wound lithium-ion cells. BDS predictions of total energy delivered under our constant C-rate battery discharge tests are within 6.5% of laboratory measurements for a full discharge and within 2.8% when a 60% state of charge window is considered.

Substrate concentration has great influence on the electrical performance of a microbial fuel cell (MFC). In this study, date syrup with a high sugar content and diversified types of nutrients was used as a substrate in a dual-chambered MFC. The results obtained were compared with glucose as a conventional substrate for power generation. A pure culture of Saccharomyces cerevisiae was used as a biocatalyst in the anode chamber and potassium ferricyanide as an oxidizing agent in the cathode side. Maximum power density of 65 mW/m² was obtained in an MFC operated with date syrup at an equivalent total carbohydrate content of 6 g/l. When the electron acceptor in the cathode side was replaced with potassium permanganate, power density was increased almost 2.5-fold and reached 234 mW/m². The system was loaded with low to high concentrations of sugar (1–7, 10, 20 and 30 g/l). However, at high concentrations of substrates, an inverse relationship with the MFC electrical performance was observed, which was most probably due to substrate inhibition in the MFC. Substrate inhibition models were applied to investigate inhibition kinetic from an electrical point of view. Tessier, Aiba and Haldane as inhibition models were well fitted with experimental data (R² = 0.98–0.99). The tested models revealed that the inhibitory effect for the substrate can be described in terms of model parameters. In order to evaluate the effect of the concentration of substrates on electrical performance, different inhibition concentrations were suggested by the models with respect to electrical responses achieved in the MFC. Copyright © 2012 John Wiley & Sons, Ltd.

In this study, the microbial fuel cell was loaded with optimum concentrations of date and glucose media, 6 and 5 g /l respectively, with 300 μmol/l potassium permanganate in the cathode. The system loaded with date syrup indicated higher electrical performance compared to glucose due to the diversified sugar contents.

Severe fluctuation of the output power is a common problem in the generating systems of various renewable energies. The concept of output power fluctuation factor of renewable energy power generating systems was put forward in this paper. Aiming to decrease the fluctuation factor of output power in solar chimney power generating systems (SC), a novel hybrid energy storage system made of water, and sandstone was employed to replace the traditional sandstone energy storage system. The mathematical models of fluid flow, heat transfer and power generating features of SC were established and the influences of material, depth, areas and location of the energy storage layer upon output power were analyzed. The simulation results indicated that adopting the hybrid energy storage of water and sandstone can effectively decrease the fluctuation factor of SC output power and hence smooth the SC output power. In addition, according to the largest daily power generating capability or the smallest peak fluctuation factor, the corresponding optimum depth of the water energy storage layer would be 5 cm or 20 cm, respectively. Copyright © 2012 John Wiley & Sons, Ltd.

Advanced fluctuation factor to analyze the output power fluctuation of renewable energy power stations water energy storage layer can reduce the variation of system output power system fluctuation factor the optimum water depth can be predicted by the reverse changing trend of peak values of system output power along with time.

A new weighted-sum-of-gray gases (WSGG) model that is based on the statistical narrow band model (SNB) RADCAL is proposed for use in computational fluid dynamic (CFD) simulations of air and oxy-combustion. When employed in conjunction with the discrete ordinates (DO) method, the model predictions compare well against line-by-line benchmark data that have been made available recently that are based on the latest spectroscopic databases. Furthermore, the model compares well against the EM2C SNB model calculations that have served as benchmark data in three-dimensional geometries. Radiative transfer calculations in these prototypical problems therefore confirm recent experimental observations that SNB RADCAL and EM2C SNB serve as good model databases to develop approximate radiative property models.

To achieve an optimum balance of speed and accuracy in computationally intensive CFD simulations, non-gray formulations of the WSGG model are also employed with the P1 model and solutions are compared against those generated by the DO model. While the P1 model gave favorable comparisons when cold, black walls were present, the errors in the surface incident radiative flux predictions increased in the presence of hot, reflecting walls.

Finally, in fully coupled simulations of natural gas combustion under air-firing and oxy-firing modes, the predicted incident radiative flux profiles were distinctly different between the gray and non-gray calculations at regions of high temperature gradients, while the centerline temperature predictions were comparatively unaffected. The effects of turbulence radiation interactions were also accounted for through the temperature self-correlation term. However, the magnitudes of the temperature fluctuations were small and localized within this furnace and did not significantly alter our predictions. Copyright © 2012 John Wiley & Sons, Ltd.

The newly proposed WSGG model (Perry 5 gg) predictions compared against line-by-line (LBL) calculations for a simulated counter-flow methane diffusion flame under air and oxy-fired conditions: (a, b) radiative source; (c, d) net radiative flux.

A new set of weighted-sum-of-gray gases (WSGG) model coefficients are proposed for use in oxy-combustion scenarios. The model predictions compare favorably against recently available benchmark data from line-by-line calculations. The RADCAL SNB-based WSGG model predictions also agree closely with those from the EM2C SNB model in 3D geometries. Non-gray predictions of the radiative source term employing the P1 model compared favorably with the discrete ordinates method. In CFD simulations of natural gas combustion, the wall radiative fluxes were distinctly different for the gray and non-gray calculations. However, the temperature fluctuations were small and localized, and therefore turbulence radiation interactions did not significantly alter our predictions.

Existing practice of nuclear desalination cogeneration incurs loss of nuclear plant power generation because it competes for live steam with nuclear plant steam turbine. Such loss is completely avoided with the nuclear desalination plant design proposed in the present study. The plant called GTHTR300 is based on a high-temperature gas reactor rated at 600 MWt. Gas turbine is used to replace steam turbine as power generator. The gas turbine converts about a half of the reactor's thermal power to electricity while rejecting the balance as sensible waste heat to be utilized in a multistage flash (MSF) plant for seawater desalination. A new MSF process scheme is proposed and optimized to efficiently match the sensible waste heat source. The new scheme increments the thermal load of the multistage heat recovery section in a number of steps as opposed to keeping it constant in the traditional MSF process. As the number of steps increases, more waste heat is utilized, and top brine temperature for peak water production is increased. Both tend to increase water yield. Operating with a similar number of stages, the new process is shown to produce 45% more water than the traditional process operating over the same temperature range. As a result, the GTHTR300 yields 56,000 m³/d water and generates 280 MWe power at constant efficiency with and without water cogeneration. Copyright © 2012 John Wiley & Sons, Ltd.

This work proposes a new multistage flash (MSF) process to improve efficiency of desalination when using nuclear reactor sensible waste heat. The process increments the load duty of the multistage heat recovery section in an optimized number of steps as opposed to keeping it constant through the section in the traditional MSF process. Operating with a similar number of stages, the new process is shown to produce as much as 45% more water than the traditional process operating over the same temperature range.

Reducing the rates of nuclear power generation for all electric power sources has been seriously discussed in Japan since the accident at the Fukushima No. 1 nuclear power plant in March 2011. Thus, the distributed power supply is expected to expand. The local production of safe and clean energy for local consumption is greatly needed in Japan. In this paper, the Saroma Lake green microgrid (SLMG), a fuel cell microgrid using tidal power generation and photovoltaics, has been planned. Energy balance equations were used to investigate this system's method of operation. Further simulated analysis of the facility, its operation cost, and the electric power quality of the network were conducted using MATLAB/Simulink, and the relationships among the capacity of a facility, the cost, and supply rate of green energy and the electric power quality (interphase voltage, frequency, and higher harmonic wave) of the power network were clarified. The total projected cost of the equipment and operation for introducing the proposed SLMG is ¥1,500,000,000/10 years. Increasing the supply rate of green energy and reducing the facility cost will require the introduction of biofuels and the reduction of the facility costs of solid oxide fuel cells in the SLMG. Copyright © 2012 John Wiley & Sons, Ltd.

The annual supply of green energy by the proposed SLMG is approximately 50 %.

Heat transfer coefficient and pressure drop correlations are used to analyse the boiling heat transfer performance potentials in plain evaporator tubes of several conventional refrigerants and two newer fluorinated propene isomers possessing low global warming potentials. These correlations are used to calculate two penalization quantities expressed in terms of the refrigerant saturation temperature drop due to pressure drop and the driving temperature difference. These penalization terms are combined into a single Performance Evaluation Criterion dubbed Total Temperature Penalization (TTP). Using the two penalization terms and the TTP, several refrigerants, including the newer alternatives R1234yf (CF₃CF=CH₂) and R1234ze(E) (CF₃CH=CHF), are evaluated for their boiling heat transfer performance potentials in plain evaporator tubes. Furthermore, the usefulness of the technique is illustrated through several examples of the optimization of evaporator tube length. Copyright © 2012 John Wiley & Sons, Ltd.

Correlations are used to calculate two penalization quantities expressed in terms of the refrigerant saturation temperature drop due to pressure drop and the driving temperature difference. Using the two penalization terms and the TTP, several refrigerants, including the newer alternatives R1234yf (CF3CF=CH2) and R1234ze(E) (CF3CH=CHF), are evaluated for their boiling heat transfer performance potentials in plain evaporator tubes.

In this paper, a novel integrated solar photovoltaic thermal absorption desalination system for freshwater and cooling production is proposed and analyzed thermodynamically. Ammonia–water pair is considered as a working fluid for the absorption system. Effect of average solar radiation for different months, time period of solar radiation availability in Abu Dhabi, salinity of seawater, and temperature of the seawater on energetic and exergetic COPs, production rate of freshwater, and overall performance of the system are investigated under different operating conditions. It is found that energetic and exergetic COPs, production rate of freshwater, energetic and exergetic utilization factors, and performance ratios vary greatly from one month to another because of the dynamic variation in solar radiation and its time of availability. The highest amount of freshwater is produced in the month of July as calculated to be 152 kg/h for a collector area of 100 m² and solar power of 4.8 kW. The highest energetic and exergetic COPs and utilization factors are also obtained for the month of July. Moreover, the highest performance ratio is found to be 0.056 as obtained in the month of July when solar radiation intensity is highest as available for more than half of a day. Copyright © 2012 John Wiley & Sons, Ltd.

A numerical model is developed from a stationary proton exchange membrane fuel cell (PEMFC) system comprising a PEMFC, a DC-DC buck converter, an auxiliary power supply (a lithium battery and supercapacitor), and a DC-AC inverter. The transient and steady-state performance of the PEMFC system is investigated by means of Matlab/Simulink simulations. It is shown that a good agreement exists between the simulated polarization curve of the PEMFC and the experimental results presented in the literature. In addition, it is shown that the DC-DC buck converter provides an effective means of stabilizing the output voltage of the PEMFC. Finally, the results confirm the effectiveness of the auxiliary power source in enabling the PEMFC to satisfy the peak load demand. Copyright © 2012 John Wiley & Sons, Ltd.

For several years recently, the price of oil has fluctuated due to the weak US dollar and financial risks. In particular, the WTI crude oil price reached $147 per barrel in July of 2008, which is the highest price thus far. An awareness of an impending crisis and concern over climate change are driving an increase in R&D for alternative energy sources instead of fossil-based energy. However, the researches based on traditional method show negative options about the economic value of new and renewable energy. This paper evaluates the value of new and renewable energy through a real option method which considers the uncertainty associated with fossil energy and the uncertainty of the success of R&D. The evaluating model assumes that the fossil energy price follows a geometric mean reverting process and that the probability of success with R&D on renewal forms of energy follows a binomial probability model. The model considers four options: the option to continue R&D, the option to delay R&D, the option to deploy R&D, and the option to abandon R&D. Finally, the value of Korean R&D on renewal forms of energy is analyzed by the model. Copyright © 2012 John Wiley & Sons, Ltd.

In this paper, three-dimensional (3D) power distribution of newly designed small nuclear reactor core has been achieved by using neutron kinetic/thermal hydraulic (NK/TH) coupling. This is pressurized water reactor-based small nuclear reactor in which plate type fuel element has been used and the core of the reactor has hexagonal type geometry. This paper depicts the design of the reactor core by using coupling approach of neutronics(Neutron Kinetic) and thermal hydraulic studies. For this purpose, neutronic analysis has been obtained by using lattice physics code, i.e. HELIOS and neutron kinetic code, i.e. REMARK. HELIOS code gives the cross-section data which is being used as input to the REMARK code. At the same time, THEATRe code was used for the thermal hydraulic analysis of the reactor core. In the coupling process, some data (fuel temperature, moderator temperature, void fraction, etc.) from THEATRe code has been used in conjunction with HELIOS and REMARK codes. After finalizing the NK/TH coupling, 3D evaluation of the power distribution of the reactor core has been achieved and is included in the paper. The purpose of this paper is to evaluate the design and get the normal operational behavior of the reactor core by NK/TH coupling approach. Copyright © 2012 John Wiley & Sons, Ltd.

Refrigeration by an active magnetic regenerative system (AMR) is potentially more attractive, as compared to conventional techniques. Indeed, devices based upon an AMR cycle are more efficient, compact, environment-friendly and can operate over a broad range of temperatures. In this paper, attention is focused to the near room-temperature range.

On the other hand, however, the AMR cycle poses a variety of complex problems, in terms of fluid dynamics, heat transfer and magnetic field. In order to identify the optimal operational parameters, the design and optimization of a magnetic refrigeration system can be supported by modelling. In this paper, a dimensionless approach was adopted to simulate an AMR cycle following a Brayton regenerative cycle. In the simulation, the temperature range that has been explored is 260 – 280 K and 275 – 295 K. The heat transfer mediums are, respectively, water–glycol mixture (50% by weight) and pure water. The Gd_0.8Dy_0.2 alloy and pure Gd have been chosen as constituent material for the regenerator of the AMR cycle. With this model, the influence of the different parameters on cycle efficiency has been analysed. In particular, the study has been focused on the influence of the secondary fluid properties, magnetic material particle diameter, fluid blow time, secondary fluid mass flow rate, regenerator geometry and effect of axial thermal conduction. The model enables to find optimal dimensionless numbers in order to maximize the cycle performances. The results can be extended to widely different situations and therefore can be easily employed for the design and the optimization of new experimental prototypes. Copyright © 2012 John Wiley & Sons, Ltd.

• Active magnetic regenerative cycle (AMR) as an alternative to vapour compression plants.

• A dimensionless numerical model to simulate an AMR cycle operating with a Brayton regenerative cycle.

• Analysis of the effect of the main operational parameters on cycle performances.

Currently, governments and companies aim their concern about the environmental problems and energy security. Within this context, the use of renewable hydrogen is presented as an interesting option.

This paper presents the alternative to use a renewable resource abundant in the country: hydroelectricity. The public transport service in the urban area of Foz do Iguaçu city, Brazil, was chosen as the scenario where a simulated replacement of the current diesel bus fleet with fuel cell buses was performed.

The focus was to take advantage of the energy called Spilled Turbinable Energy (STE) verified by the ITAIPU Hydroelectric Power Plant from 2001 to 2006 in order to produce hydrogen by water electrolysis process. The paper does not contain thermodynamic analysis of the processes involved in the proposal. Based on the monthly average, the maximum value was 1,054,899 MWh and the minimum 9559 MWh. Evaluating the historic behavior of this potential energy in the considered period, from October to June, it was found that the energy demand to produce the electrolytic hydrogen needed to meet the whole demand of the public transport sector of Foz do Iguaçu city, estimated in 14,454.3 MWh/month, amounts only between 1.5% to 8.5% of total spilled energy.

This study presents two electrolytic hydrogen production models: the centralized and the decentralized associated with various distribution modes. The comparison between models shows that the centralized hydrogen production associated with central supply mode are economically more convenient for the city, and the hydrogen cost achieved was US$ 2.38/kg in contrast with the decentralized model associated with cryogenic liquid delivery which showed the highest cost, equal to US$ 4.61/kg. Finally, a sensitivity analysis was performed varying four parameters: equipment cost; rate of return; capital recovery time and electricity cost. Copyright © 2012 John Wiley & Sons, Ltd.

In this paper, the effects of microporous layer (MPL) addition and polytetrafluoroethylene (PTFE) loading of gas diffusion layers (GDLs) on the overall performance of the proton exchange membrane fuel cell have been investigated. The focus was on fuel cells that operate at relatively low current densities where the power demand is low, but the efficiency is of concern. The results show that, in the activation loss-controlled region, the performance of the fuel cell operating with moderately PTFE-treated carbon substrates is superior over that operating with coated GDLs. This is due to the addition of the MPL which lengthens the diffusion paths and significantly reduces the mass transport properties. Conversely, in the ohmic loss-controlled region, the fuel cell with coated GDLs performs better than those with carbon substrates. This is explained by the enhanced contact of the GDL with the adjacent components after the MPL addition, which outweighs the negative effects associated with the activation loss-controlled region. Also, it was found that the fuel cell performance becomes lower if the GDL is treated with a relatively high PTFE loading in either the carbon substrate (due to the decrease in the porosity of the GDL) or the MPL. Copyright © 2012 John Wiley & Sons, Ltd.

The operation point of the fuel cell determines whether the addition of the microporous layer (MPL) is beneficial for its performance or not. In this paper, in the low current density region, it has been shown that the fuel cell performs better with a moderately PTFE-treated uncoated GDL (10 BA in the graph). However, as shown for the polarisation curves associated with the MPL-coated GDLs, i.e. 10BC and 10BE, the benefit of MPL-coating is realised in the intermediate current density region where the ohmic losses are dominant.

In order to prevent the inert alumina film from forming on the surface of Al metal particles, Li is added into Al to form Al–Li alloy. It can improve the reactivity of Al with water. The prepared Al–Li alloy can rapidly split water to produce hydrogen. With increasing Li content of alloy, the hydrogen generation rate is promoted. The ultimate hydrogen yields of samples can reach 100%. The effect of initial water temperature on the hydrogen generation has been investigated. Even in the water at 0 °C, hydrogen can also be produced rapidly. Composition of solution has some effect on the hydrogen generation. Especially, Mg²⁺ or NO₃⁻ has negative influence on the hydrogen generation and can reduce the ultimate hydrogen yield of alloy. Longer air exposure time will also decrease the ultimate hydrogen yield. After reaction, Al and Li enter into the residue in the form of LiAl₂(OH)₇·2H₂O and LiAl₂(OH)₇·xH₂O or Al(OH)₃. After calcinations, these reaction by-products can be easily recycled by existing metallurgical process. Copyright © 2012 John Wiley & Sons, Ltd.

This paper documents the fundamental problem of designing a porous flow architecture that meets the requirements of facilitating flow access while storing and releasing heat to a flowing fluid. Examples of such designs are regenerators that operate cyclically in various types of heating or reheating furnaces. The main geometrical scales are determined for parallel flow channels in a fixed regenerator volume with a fixed porosity, by matching the time scales of convection along the channels and thermal diffusion. In accord with the constructal law, the route to better architectures for maximum heat transfer and minimum pressure losses is the morphing of the regenerator architecture from parallel channels to dendritic channels. Copyright © 2012 John Wiley & Sons, Ltd.

The present paper describes the analysis of the melting process in a single vertical shell-and-tube latent heat thermal energy storage (LHTES), unit and it is directed at understanding the thermal performance of the system. The study is realized using a computational fluid-dynamic (CFD) model that takes into account of the phase-change phenomenon by means of the enthalpy method. Fluid flow is fully resolved in the liquid phase-change material (PCM) in order to elucidate the role of natural convection. The unsteady evolution of the melting front and the velocity and temperature fields is detailed. Temperature profiles are analyzed and compared with experimental data available in the literature. Other relevant quantities are also monitored, including energy stored and heat flux exchanged between PCM and HTF. The results demonstrate that natural convection within PCM and inlet HTF temperature significantly affects the phase-change process.

Thermal enhancement through the dispersion of highly conductive nanoparticles in the base PCM is considered in the second part of the paper. Thermal behavior of the LHTES unit charged with nano-enhanced PCM is numerically analyzed and compared with the original system configuration. Due to increase of thermal conductivity, augmented thermal performance is observed: melting time is reduced of 15% when nano-enhanced PCM with particle volume fraction of 4% is adopted. Similar improvements of the heat transfer rate are also detected. Copyright © 2012 John Wiley & Sons, Ltd.

Pakistan though a developing country has a strong agrarian economy which in turn leads to a strong resource of biomass. Further, the effects of climate change scenario discourage the use of biomass as a combustion fuel. An integrated renewable hydrogen model has been developed based on biomass feed stocks as the input material for hydrogen production. It has been found that hydrogen can be produced at rates comparable with steam methane reforming, which is one of the most economical methods of generating hydrogen. However, the model must have a strong statistical base and an up-to-date geographical information system to present accurate and logical results for effective energy planning. Copyright © 2012 John Wiley & Sons, Ltd.

The multi-objective optimization of a direct methanol fuel cell system was conducted with the objective functions of maximizing both the power output and energy and exergy efficiencies depending on the comprehensive exergy analysis of this study. This advanced model is mounted into the developed computer program multi-objective optimizer which is based on an improved genetic algorithm. The problem is solved parametrically depending on the on the multi-objective optimization objective function ratios which allows a chance to investigate the trade-offs and the importance of the objectives. The investigated parameters are the varying available operating conditions, such as temperature, concentration, and current density. The best results found for each objective were 9.72 W for the power produced and 10.732 and 10.467 energy and exergy efficiency, respectively. However, the best optimum for the overall investigation, taking the fitness function into consideration, was 9.59 W for the power and 10.248 and 9.995 energy and exergy efficiencies. Copyright © 2012 John Wiley & Sons, Ltd.

A general model for an irreversible solar-driven Brayton multi-step heat engine is presented. The model incorporates an arbitrary number of turbines (N_t) and compressors (N_c) and the corresponding reheating and intercooling processes; thus, the solar-driven Ericsson cycle is a particular case where N_t, N_c → ∞. For the solar collector, we assume linear heat losses, and for the Brayton multi-step cycle, we consider irreversibilities arising from the non-ideal behavior of turbines and compressors, pressure drops in the heat input and heat release, heat leakage through the plant to the surroundings, and non-ideal couplings of the working fluid with the external heat reservoirs. We obtain the collector temperatures at which maximum overall efficiency η_max is reached as a function of the thermal plant pressure ratio, and a detailed comparison for several plant configurations is given. This maximum efficiency is obtained in two cases: when only internal irreversibilities are considered and when both internal and external irreversibilities (which corresponds to the fully irreversible realistic situation) are simultaneously taken into account. Differences between both situations are stressed in detail. In the fully irreversible realistic case, it is possible to perform an additional optimization with respect to the pressure ratio, . In particular, this double optimization leads to a valuable increase in efficiency (between 34% and 65%) for a plant with two turbines and two compressors compared to the simple solar-driven one-turbine one-compressor Brayton engine. Copyright © 2012 John Wiley & Sons, Ltd.

This paper evaluates the economic, energetic, and environmental feasibility of using two power generation units (PGUs) to operate a combined heat and power (CHP) system. Several benchmark buildings developed by the Department of Energy simulated using the weather data for Chicago, IL, are used to analyze the proposed configuration. This location has been selected because it usually provides favorable CHP system conditions in terms of cost and emission reduction. For the proposed configuration, one PGU is operated at base load to satisfy part of the electricity building requirements, whereas the other is used to satisfy the remaining electricity requirement operating following the electric load. The dual-PGU CHP configuration (D-CHP) is modeled for four different scenarios to determine the optimum operating range for the selected benchmark buildings. The dual-PGU scenario is compared with the reference building using conventional technology to determine the benefits of this proposed system in terms of operational cost, primary energy reduction, and carbon dioxide emissions. The D-CHP system results are also compared with a CHP system operating following the electric load (FEL) and base-loaded CHP system. For three of the selected buildings, the proposed D-CHP system provides comparable or greater savings in operating cost, primary energy consumption, and carbon dioxide emissions than the optimized conditions for base loading and FEL. In addition, the effect of operating the D-CHP system only during certain months of the year on the overall operational cost is also evaluated. Results indicate that not operating the D-CHP system for the months where the thermal load is too low is beneficial for the overall system performance. Copyright © 2012 John Wiley & Sons, Ltd.

Supercritical water gasification of crude glycerol for hydrogen (H₂) production is one possible use of crude glycerol from biodiesel production. In this study, a series of central composite designed experiments were conducted to investigate the reforming of crude glycerol for producing a H₂ rich gas. A mathematical model defining the effect of glycerol concentration, reaction temperature and KOH concentration was developed with response surface methodology and was used to improve the H₂ yield. The study revealed that the optimum reaction conditions for producing H₂ were 500°C, 7 wt.% glycerol concentration and 2.39 mol L^-1 KOH concentration. The corresponding pressure was 45 MPa. Under these optimized reaction conditions, the H₂ mole fraction yield in the gaseous product was 27.9 ± 0.22 mol%. The mole fraction yields of other gas products (CH₄, CO and CO₂) were small compared to that of H₂. Copyright © 2012 John Wiley & Sons, Ltd.

In order to transport and store the captured CO₂ from coal-fired power plants, it is necessary to compress and liquefy CO₂ first. However, the power consumption of conventional process is enormous. In this paper, a novel process for CO₂ compression and liquefaction based on the analysis of the power consumption of traditional method is proposed. The new process integrates the refrigeration process driven by the lower level heat from the coal-fired power plant. This paper analyzes and compares the energy consumptions of conventional process and new process for CO₂ compression and liquefaction. The research result indicates that, when CO₂ needs to be compressed and liquefied and an abundant low quality heat is available, the new process has obvious superiority in lowering the energy consumption. The new process for CO₂ compression and liquation integrated with the exhaust heat powered refrigeration can greatly reduce the work consumption of CO₂ compression and liquefaction. The refrigeration temperature has great effects both on the coefficient of performance of refrigeration process and work consumption of compressors. The refrigeration temperature can be selected by optimization. Using refrigerator with double stages of evaporation can further reduce the amount of the extracted steam and lower the total energy consumption for CO₂ compression and liquation. Recovering the cool energy of CO₂ is beneficial to the reduction of the total work consumption. The achievements obtained from this paper will provide a useful reference for CO₂ compression and liquefaction with the lower energy consumption. Copyright © 2012 John Wiley & Sons, Ltd.

The Stirling engine performances depend on several physicals characteristics and functioning parameters. The influence of each parameter and of their interactions is difficult to achieve with classical univariate studies. The experimental design is an alternative to identify the parameters sets allowing optimal Stirling engine performances. Hence, a four factor Central Composite Rotatable Design was used to observe the effect of cooling water flowrate, initial charge pressure, heating temperature, and operation time on a Stirling engine brake power. The influence of each parameter and the effect of the interaction between two or three parameters on the engine performances are presented and discussed. Using the surface response method, it appears that initial charge pressure and heating temperature are the more influencing parameters on the Stirling engine performances. With modeling, optimal conditions for the Stirling engine functioning are the following: charge pressure of 8 bar, heating temperature of 500 °C, and cooling water flow rates of 7.34 l/min, independent of the engine operation time. Copyright © 2012 John Wiley & Sons, Ltd.

Corrosion behaviors of Fe-26Mn-3A1-7Cr alloy are investigated in the solution of 0.05 M H₂SO₄ + 2 ppm F^-, and interfacial contact resistances (ICRs) are measured before and after potentiostatic polarization at operation potentials. The results show that passive current densities of Fe-26Mn-3A1-7Cr alloy are about 10^-5 A cm^-2. Stable passive film forms on the surface of Fe-26Mn-3A1-7Cr alloy in the cathodic side, and no pit is observed, while serious dissolution occurs in the anodic one. The ICR of Fe-26Mn-3A1-7Cr alloy in anode side is about three times higher than that in cathode one. Copyright © 2012 John Wiley & Sons, Ltd.

The plant microbial fuel cell (PMFC) is a technology for the production of renewable and clean bioenergy based on photosynthesis. To increase the power output of the PMFC, the internal resistance (IR) must be reduced. The objective of the present study was to reduce the membrane resistance by changing the transport direction of cations in the direction of the established concentration gradient. Two setups, a MFC and PMFC, were designed with one anode and two cathode compartments to demonstrate the effect of changing the transport direction. This design allowed changing the direction of transport of cations by switching the cathode compartment that functions as cathode. The change between cathode 1 and cathode 2 enhanced the power output of the PMFC by 398%. More specifically, after changing transport direction, the increase in power output was due to the reduction of IR (normalized to membrane area) from 4.3 Ω m²_mem to 1.2 Ω m²_mem in the PMFC.

Consecutive changes of cathodes resulted in an increase of generated power with cathode 1 while this power decreased for cathode 2. During the consecutive changes, the average power output remained constant 0.0362 ± 0.0005 W m⁻²_mem; this was 246% higher than the initial power output with cathode 1. Copyright © 2012 John Wiley & Sons, Ltd.

Increase in power density by changing cation transport direction. The initial situation is cathode 1 before the change, after the change of transport direction the cell potential increased. The increase in cell potential resulted in an increase of power output 398 % for the PMFC.

Hydrogen peroxide (H₂O₂) and the reduction/oxidation by-products of peroxide are non-toxic to humans and the environment. Simple, low-concentration hydrogen-peroxide solutions used as fuel and direct peroxide/peroxide fuel cells (DPPFCs) face significant challenges in the development of a new class of power generators. A power density of 10 mWcm⁻² at a cell potential of 0.55 V have been achieved with a DPPFC composed of carbon-paper-supported nickel as the anode catalyst and carbon-paper PbSO₄ as the cathode catalyst. The catalysts have been prepared by electroless deposition. Using non-precious metals rather than platinum in our FC makes the cell cost effective comparable to that of PEMFCs. Additionally, as a low-price fuel, H₂O₂ reduces the cost of this FC. Copyright © 2012 John Wiley & Sons, Ltd.

In this study, the oxidation mechanism of hydrogen sulfide (H₂S) is investigated, and a fuel cell operating with acidic peroxide as oxidant and basic hydrogen sulfide as fuel is constructed. A stable solid state H₂S/H₂O₂ fuel cell has been developed at the temperature of 298 K. A nickel anode catalyst has been examined using Nafion-117 as a proton-conducting membrane. In an operating with the acidic hydrogen peroxide (H₂O₂) as oxidant, the cell potential was increased to a value of 0.85 V at 298 K. The main conclusion of this study is the management to increase the cell potential to 850 mV at 25 °C, whereas this value can only be achieved in the H₂S/O₂ fuel cell at 850–1000 °C. Moreover, there exists no prior work on the H₂S/H₂O₂ fuel cell research. Copyright © 2012 John Wiley & Sons, Ltd.

Building cooling heating power (BCHP) systems as a kind of distributed energy resource have shown a great potential in improving energy efficiency and meeting multiple energy demands in buildings. In this paper, we present a BCHP system driven by solar energy with flat-plate solar collectors. A modified system efficiency is introduced to evaluate the whole day performance of the system more accurately. Based on the mathematical models and simulation platform established, we have investigated the influences of some key thermodynamic parameters, namely condensation temperature, turbine inlet temperature and turbine inlet pressure on the system performance. In order to find the optimum combination of these parameters that leads to the best performance, we have performed parametric optimization by means of the genetic algorithm. Results indicate that the best performance and the highest efficiency of the system are achieved when the working fluid reaches its saturated state and the corresponding efficiencies of the system operating in the combined heating power mode, the combined cooling power mode and the power production mode turn out to be 19.10%, 27.24% and 10.47%, respectively. Copyright © 2012 John Wiley & Sons, Ltd.

The catalytic activity of single-wall carbon nanohorns (SWNH) as counter electrodes (CE) of dye-sensitized solar cells (DSC) was studied for the iodide/triiodide redox reaction. The catalytic activities of SWNH and high surface SWNH (HS-SWNH) obtained by partial oxidation of SWNH were assessed based on charge-transfer resistances (R_ct) and current–voltage curves. A half-cell configuration was used, and CE performances were compared to CEs made of carbon black (CB) and Pt. A CE assembled with HS-SWNH and mixed with 10 wt.% of hydroxyethyl cellulose (HEC) - HS-SWNH/HEC was found to have the highest electrocatalytic activity (lowest R_ct) among all the carbon-based CEs tested when annealed at 180 °C (R_ct = 141 Ω cm²); however, a very thick film (several tens of µm) would be required in order to perform comparably to a Pt CE. The annealing of such CE at higher temperatures (above 400 °C) did not improve its catalytic activity, contrary to the other studied carbonaceous CEs.

The redox catalytic activity of SWNH and HS-SWNH decorated with Pt was also studied on a half-cell configuration and compared to that of Pt/CB and pristine Pt. The Pt/SWNH/HEC CE showed the highest electrocatalytic activity per mass of Pt, needing just 50% of Pt load to yield the same electrocatalytic activity of a DSC equipped with a Pt CE, but having half of its transparency. Additionally, applications in temperature-sensitive substrates are envisioned for the Pt/SWNH/HEC CE due to the use of lower annealing temperatures. Copyright © 2012 John Wiley & Sons, Ltd.

Although the energy crisis has been slightly abated in the recent times, the possibility of a crisis caused by extremely high oil prices is still imminent. Simultaneously, the environmental crisis represented by climate change is further the major concern which requires an immediate solution. Hence, in this research, economical and environmental assessment of utilizing renewable energies in comparison with natural gas have been investigated which resulted to choose the best economically–environmentally alternative for power generation.

Equivalent uniform annual value and scaling-weighting check list with experts' comments through analytical hierarchy process have been applied for economical and environmental assessment, respectively. Afterward, the results of normalized economical and environmental assessment have been coalesced to gain a combined economical–environmental perspective.

As economical surveys, four scenarios have been considered. The results reveal that the best choices are conventional steam cycle, combined cycle, and biogas if power is sold to consumer (other technologies have negative net present value in this scenario), respectively, without considering the social costs and the emission reduction. If power is sold to government, biogas, conventional steam cycle, combined cycle, and wind are technological priorities.

In case of considering social costs and emission reduction incomes, the best choices are biogas, combined cycle, and conventional steam cycle, respectively, if power is sold to consumers. If not, the priorities are biogas and wind.

Furthermore, environmental surveys have indicated that wind is the most applicable environmentally friendly energy to produce electricity with negative impact magnitude (NIM) of 1.3 (out of 10). In addition, photovoltaic, biogas, and hydropower remain at the next levels with NIM of 1.6, 1.7, and 3.2 (out of 10), respectively. While conventional steam cycle has 6.2 of NIM.

Eventually, the combination of economical and environmental evaluation reveals that wind farms and biogas plants with normalized weight of 3.10 (310%) and 2.34 (234%) are the best choices of electricity generation method, respectively. Moreover, the least applicable one is conventional steam cycle with normalized weight of 0.63 (63%).

To sum it up, wind farms and biogas plants are about five and four times more economical–environmental beneficial than conventional steam cycle power generation. Copyright © 2012 John Wiley & Sons, Ltd.

The effects of several modifications on TiO₂ P25 in producing hydrogen from glycerol–water mixture have been investigated. Prior to further modification, TiO₂ underwent hydrothermal treatment at 130°C for several hours to obtain nanotube shape. TiO₂ nanotubes (TiNT) was then doped with platinum (Pt) and nitrogen (N) by employing photo-deposition and impregnation method, respectively. SEM and XRD results showed that Pt-N-TiNT was successfully obtained as pure anatase crystal structure. The effects of glycerol content to photocatalytic activity of hydrogen production have also been studied, result in 50%v of glycerol as the optimum concentration correspond to the stoichiometric volume ratio of glycerol reforming. The results of photo-production test showed that TiNT (nanotube) could enhance hydrogen generation by two times compared with unmodified P25 (nanoparticle). Meanwhile, simultaneous modification of TiNT by Pt and N dopants (Pt-N-TiNT) lead to activity improvement up to 13 times compared with P25. The output of this study may contribute toward finding an alternative pathway to produce H₂ from renewable resources. Copyright © 2012 John Wiley & Sons, Ltd.

The optimal design for heat recovery steam generator (HRSG) should be chosen based on technical and economic considerations. Therefore, parameters that are related to thermodynamic and economic aspects should be considered in optimization approaches. It is worth mentioning that one of the significant issues in the HRSG design is the diversity of arrangements between various components (economizer, evaporator, and superheater), which absolutely affect the HRSG performance. According to these facts, in the present article, different arrangements of a dual pressure HRSG are analyzed, and the economizer at the high-pressure level is divided into two parts; these arrangements are optimized by applying different optimization approaches to achieve the optimal configuration. These approaches include the reduction of gas pressure drop, the reduction of generated steam cost and the consideration of both approaches as the third approach. These three approaches are also considered to perform economic and thermodynamic optimization. With regard to the limitations of optimization such as the pinch and approach point, seven different configurations are considered. First, a comprehensive model is developed for calculating thermodynamic, heat transfer, and pressure loss. To perform a thorough optimization, both thermodynamic and geometric variables as well as diversity of various arrangements is considered using genetic algorithm. The results of the optimization study show that the best arrangement is not unique, and each arrangement has different characteristics. Hence, the best arrangement for the HRSG is chosen according to the importance of the objective functions. Copyright © 2012 John Wiley & Sons, Ltd.

Present work analyzes and compares two quintuple effect evaporation units with and without heat recovery devices being employed. It is based on actual operational data of sugar plant. This study is primarily based on exergy analysis. Case A is a quintuple effect evaporation unit without heat recovery devices, while case B is with heat recovery devices. The average exergy efficiency is found to be 70.53% for case A, while it is 86.71% for case B. Highest exergy destruction for case A is in second effect with a value of 1562.20 kW, and for case B, it is for the first effect with a value of 1871.68 kW. Steam economy for case A is 1.99, while for case B, it is 3.46. This is due to high evaporation rates and heat recovery devices being employed for case B. The fifth effect evaporator in case A and first effect evaporator in case B are found to be the least efficient components from exergy point of view. As energy economy is concerned in terms of exhaust steam demand, case B is more attractive than case A. However, in terms of exergy, case B is less sustainable than case A. A parametric study indicated that increase in the exhaust/inlet steam temperature is highly disadvantageous in terms of exergy and quality of the end product. The authors expect that the exergy analyses results would facilitate the designers and professional practioners in the field of sugar engineering in furthering the goal of improving energy systems. Copyright © 2012 John Wiley & Sons, Ltd.

In this paper, an experimental work is carried out to investigate the characteristics of solar thermal collection using supercritical CO₂. This solar thermal conversion is based on supercritical CO₂ natural convection, which is much easily induced because a small change in temperature can result in large change in density close to the critical point. In addition, its critical temperature is 31.1°C and low enough to be easily reached in the low-temperature solar thermal conversion system. The obtained results show that the supercritical CO₂ flow rate is smooth curve and not affected by the sudden variation of the solar radiation. The solar thermal conversion operation process can be divided into three periods: starting-up, transition, and stable period. When the system reaches the stable period, the CO₂ flow rate will keep at a high value even if the solar radiation stays at a low level. It is also found that the smaller local solar radiation variation is, the better ability of keeping the flow rate near the peak level the supercritical CO₂ fluid owns. It is also found that a small pressure difference can drive a supercritical CO₂ flow with high flow rate. Furthermore, high solar thermal conversion efficiency is found at a high mass flow rate and under operation pressure near the critical point. Copyright © 2012 John Wiley & Sons, Ltd.

A novel absorption–compression hybrid refrigeration cycle (ACHRC) driven by gases and power from vehicle engines is proposed in this article, in which R124–dimethylacetamide is used as working fluid. The ACHRC composes the absorption refrigeration subcycle powered by exhaust gases and the compression refrigeration subcycle driven by power from both automotive engines. It can also meet the technical requirements for vehicle air-conditioning systems. The thermal calculation for the ACHRC was performed under the given operating conditions in which the temperatures of cooling air, condensation and evaporation are 35 °C, 55 °C and 3 °C, respectively, and the coach air-conditioning load is 30 kW. The operating characteristics of the ACHRC, which vary with the generator load ratio and cooling air temperature, have been simulated and analyzed. The simulation results show that the maximum integration coefficient of performance of the ACHRC can reach 14.85 under the given operating conditions. Copyright © 2012 John Wiley & Sons, Ltd.

In this paper, a transcritical carbon dioxide heat pump system driven by solar-owered CO₂ Rankine cycle is proposed for simultaneous heating and cooling applications. Based on the first and second laws of thermodynamics, a theoretical analysis on the performance characteristic is carried out for this solar-powered heat pump cycle using CO₂ as working fluid. Further, the effects of the governing parameters on the performance such as coefficient of performance (COP) and the system exergy destruction rate are investigated numerically. With the simulation results, it is found that, the cooling COP for the transcritical CO₂ heat pump syatem is somewhat above 0.3 and the heating COP is above 0.9. It is also concluded that, the performance of the combined transcritical CO₂ heat pump system can be significantly improved based on the optimized governing parameters, such as solar radiation, solar collector efficient area, the heat transfer area and the inlet water temperature of heat exchange components, and the CO₂ flow rate of two sub-cycles. Where, the cooling capacity, heating capacity, and exergy destruction rate are found to increase with solar radiation, but the COPs of combined system are decreased with it. Furthermore, in terms of improvement in COPs and reduction in system exergy destruction at the same time, it is more effective to employ a large heat transfer area of heat exchange components in the combined heat pump system. Copyright © 2012 John Wiley & Sons, Ltd.

A design and simulation study of the four-step copper–chlorine (Cu–Cl) cycle using Aspen Plus software (Aspen Technology Inc., Cambridge, MA)is reported. The simulation consists of four main sections: hydrolysis, oxy-decomposition, electrolysis, and drying. This paper explains and justifies how the actual reaction kinetics is factored into these four main sections. Also, it illustrates all the process units that are used in the simulation of four-step Cu–Cl cycle, providing their associated specifications and design parameters. It is found that hydrolysis reactors with smaller capacities and larger (≥10/1) steam to CuCl ratios were desirable to increase the reaction efficiency and prevent the formation of side products such as CuO and CuC. In contrast, larger capacity oxy-decomposition reactors with longer residence times are preferable to allow enough time for the copper oxychloride to decompose. Therefore, 10 (or more) small-scale hydrolysis reactors can feed one oxy-decomposition reactor with large capacity to keep continuity of the flow in the overall cycle. On the basis of the process flow sheet, a pinch analysis is developed for an integrated heat exchange network to enable effective heat recovery within the Cu–Cl cycle. Copyright © 2012 John Wiley & Sons, Ltd.

High-purity hydrogen generated by the hydrolysis of sodium borohydride can be used as proton exchange membrane fuel cells (PEMFCs) for portable device applications. Because of its advantages in high storage capacity, controllable reaction, and mild condition, hydrogen generation by catalytic hydrolysis of a chemical hydride, such as sodium borohydride, has recently attracted much attention for development. Hydrogen generated by the hydrolysis of sodium borohydride using a Ru catalyst is reported in the present study. A multi-layer coating process was used on the Ru/Ni foam catalyst to enhance the cycling generation. The optimal deposition density of the Ru particle on Ni foam was confirmed by SEM morphology. The cycling generation for the steady state reaction can be maintained at least 10 times, and gradually decreases to 82% performance after the 17th cycling generation.

It was found that a combination of 20 wt% NaBH₄ solution concentration and 3 wt% NaOH yields the highest performance for hydrogen generation. A hydrogen generation efficiency of 95% was obtained for a solution with a 1-g/min flow rate flowing onto the 6-cm² area of a catalyst plate, which had a hydrogen generation rate of 0.45 L/min. As the solution flow rate was increased, the reaction efficiency decreased because of the decreased reaction time. Hydrogen fuel saturated with water generated by a NaBH₄ solution shows an advantage over that from a gas cylinder for fuel cell operation. A PEM fuel cell was integrated with the hydrogen generator in the present study. The hydrogen fuel from the hydrogen generator with saturated water vapor showed a better cell performance compared with using hydrogen from a gas cylinder. Copyright © 2012 John Wiley & Sons, Ltd.

A novel photocatalytic mop fan air cleaning system has been developed. The novel mop fan system is optimized in terms of the pollutant degradation efficiency, energy consumption, appearance and cost reduction based on previous research. The fluid dynamic characteristic and energy consumption of the novel mop fan system has been identified by experimental testing. Pollutant degradation effect of the mop fan on a typical industry pollutant, diesel fume, has also been tested. It was found that the system has very low energy consumption and is very effective to destroy the diesel fume, a microparticulate pollutant. The system is suitable for any indoor environment to clean the air by removing the particulates, odors, virus, bacteria and volatile organic pollutants. Copyright © 2012 John Wiley & Sons, Ltd.

Integration of wind machines and battery storage with the diesel plants is pursued widely to reduce dependence on fossil fuels. The aim of this study is to assess the impact of battery storage on the economics of hybrid wind-diesel power systems in commercial applications by analyzing wind-speed data of Dhahran, East-Coast, Kingdom of Saudi Arabia (K.S.A.). The annual load of a typical commercial building is 620,000 kWh. The monthly average wind speeds range from 3.3 to 5.6 m/s. The hybrid systems simulated consist of different combinations of 100-kW commercial wind machines (CWMs) supplemented with battery storage and diesel generators. National Renewable Energy Laboratory's (NREL's) (HOMER Energy's) Hybrid Optimization Model for Electric Renewables (HOMER) software has been employed to perform the economic analysis.

The simulation results indicate that for a hybrid system comprising of 100-kW wind capacity together with 175-kW diesel system and a battery storage of 4 h of autonomy (i.e. 4 h of average load), the wind penetration (at 37-m hub height, with 0% annual capacity shortage) is 25%. The cost of generating energy (COE, $/kWh) from this hybrid wind–battery–diesel system has been found to be 0.139 $/kWh (assuming diesel fuel price of 0.1$/L). The investigation examines the effect of wind/battery penetration on: COE, operational hours of diesel gensets. Emphasis has also been placed on un-met load, excess electricity, fuel savings and reduction in carbon emissions (for wind–diesel without battery storage, wind–diesel with storage, as compared to diesel-only situation), cost of wind–battery–diesel systems, COE of different hybrid systems, etc. The study addresses benefits of incorporation of short-term battery storage (in wind–diesel systems) in terms of fuel savings, diesel operation time, carbon emissions, and excess energy. The percentage fuel savings by using above hybrid system is 27% as compared to diesel-only situation Copyright © 2012 John Wiley & Sons, Ltd.

This paper aims at investigating the performance of a cylindrical ion transport reactor designed for oxy-fuel combustion. The cylindrical reactor walls are made of dense, nonporous, mixed-conducting ceramic membranes that only allow oxygen permeation from the outside air into the combustion chamber. The sweep gas (CO₂ and CH₄) enters the reactor from one side and mixes with the oxygen permeate, and the products are discharged from the other side. The process of oxygen permeation through the reactor walls is influenced by the flow condition and composition of air at the feed side (inlet air side) and the gas mixture at the permeate side (sweep gas side). The modeling of the flow process is based on the numerical solution of the conservation equations of mass, momentum, energy, and species in the axisymmetric flow domain. The membrane is modeled as a selective layer in which the oxygen permeation depends on the prevailing temperatures as well as the oxygen partial pressure at both sides of the membrane. The CFD calculations were carried out using fluent 12.1 (ANSYS, Inc., Canonsburg, PA, USA), whereas the mass transfer of oxygen through the membrane is modeled by a set of user defined functions. The model results were validated against previous experimental data, and the comparison showed a good agreement. The study focused on the effect of oxygen partial pressure and temperature on the resulting combustion zones inside the reactor for the two cases of co-current and counter-current flow regimes. The results indicated that the oxygen to fuel mass ratio increases as the percentage of CO₂ increases in the inflow sweep gas for both co-current and counter-current flows. The obtained sweep mixture ratio (CO₂/CH₄) of 24 is found within the stoichiometric limit over most of the reactor length in the co-current configuration, whereas the sweep mixture ratio of 15.67 is found in the counter-current configuration owing to the high O₂ permeation. Copyright © 2012 John Wiley & Sons, Ltd.

This paper presents a flash cooling desalination system to reduce thermal pollution and also to produce freshwater using the heat rejected by the process plant into the environment. The prototype plant was erected in an existing coal-based thermal power plant at North Chennai, India. It consists of an air-tight barometric sealed flash cooler, positioned at a level at least 10.13 m above the ground level, for the feed seawater to flow under the effect of gravity and to maintain a low pressure. The prototype plant was tested by using a small fraction of the available flows without using any mechanical energy such as motive steam from the power plant. A freshwater production rate of 0.49% of the feed seawater is obtained from the available thermal gradient of 8.5 °C from the condenser reject heat of the power plant, and then the waste water is discharged at near intake concentration of salinity into the sea. The temperature of hot feed seawater is also reduced by 3 °C. The results are used to provide an outline technical specification for larger capacity desalination plant to meet the growing need for freshwater. This is an environment friendly desalination process and consumes no chemicals as it operates at near ambient temperature. This can be effectively utilized for the generation of freshwater, besides protecting the marine ecosystem along the shore, and reducing the load on the cooling tower or eliminating the need for it completely. Copyright © 2012 John Wiley & Sons, Ltd.

The construction of a reliable numerical model and the clarification of its operational conditions are necessary for maximizing fuel cell operation. Numerous operating factors, such as mole fractions of species, pressure distribution, overpotential, and inlet relative humidity, affect the performance of proton exchange membrane fuel cells (PEMFCs). Among these operational parameters, geometrical shape and relative humidity are investigated in this paper. Specifically, the land ratio of the gas channel and rib is an important parameter affecting PEMFC performance because current density distribution is influenced by this geometrical characteristic. Three main variables determine the current density distribution, namely, species concentration, pressure, and overpotential distributions. These distributions are considered simultaneously in assessing fuel cell performance with a given PEMFC cell-operating voltage. In this paper, three different land ratio models are considered to obtain better PEMFC performance. Similarly, three different inlet relative humidity variations are studied to achieve an enhanced operating condition. A three-dimensional numerical PEMFC model is developed to illustrate the current density distribution as the determining factor for PEMFC performance. Copyright © 2012 John Wiley & Sons, Ltd.

In this paper, a novel thermally driven pump is introduced, and its test in a closed supercritical CO₂ loop cycle system is studied. The thermally driven pump is a refrigerant-circulating pump composed of two expansion tanks, which has less electricity consumption and better reliability compared with conventional mechanical pumps. Experimental results showed that the system efficiency of the present thermally driven pump in the supercritical CO₂ loop can be enhanced compared with that using the mechanical feed pump. In addition, it was found that the system efficiency with the thermally driven pump decreases with the outlet temperature of condenser. The thermal energy utilization efficiency of the loop system with the thermally driven pump can be increased when the condenser has higher efficiency. Copyright © 2012 John Wiley & Sons, Ltd.

In this study, a series of computational fluid dynamics (CFD) numerical analyses was performed in order to evaluate the performance of six full-scale closed-loop vertical ground heat exchangers constructed in a test bed located in Wonju, South Korea. The high-density polyethylene pipe, borehole grouting and surrounding ground formation were modeled using FLUENT, a finite-volume method program, for analyzing the heat transfer process of the system. Two user-defined functions accounting for the difference in the temperatures of the circulating inflow and outflow fluid and the variation of the surrounding ground temperature with depth were adopted in the FLUENT model. The relevant thermal properties of materials measured in laboratory were used in the numerical analyses to compare the thermal efficiency of various types of the heat exchangers installed in the test bed. The numerical simulations provide verification for the in-situ thermal response test (TRT) results. The numerical analysis with the ground thermal conductivity of 4.0 W/m⋅K yielded by the back-analysis was in better agreement with the in-situ TRT result than with the ground thermal conductivity of 3.0 W/m⋅K. From the results of CFD back-analyses, the effective thermal conductivities estimated from both the in-situ TRT and numerical analysis are smaller than the ground thermal conductivity (=4.0 W/m∙K) that is input in the numerical model because of the intrinsic limitation of the line source model that simplifies a borehole assemblage as an infinitely long line source in the homogeneous material. However, the discrepancy between the ground thermal conductivity and the effective thermal conductivity from the in-situ TRT decreases when borehole resistance decreases with a new three pipe-type heat exchanger leads to less thermal interference between the inlet and outlet pipes than the conventional U-loop type heat exchanger. Copyright © 2012 John Wiley & Sons, Ltd.

The decomposition of hydrogen sulfide (H₂S) to hydrogen and sulfur with Al₂O₃, MoO_x/Al₂O₃, CoO_x/Al₂O₃ and NiO/Al₂O₃ packed non-thermal plasma dielectric barrier discharge reactor was studied. The reaction was carried out with 5-mm discharge gap during the decomposition of 5 vol.% H₂S at 150 ml/min (STP) flow rate. Typical results indicated the conversion of ~50% at a specific input energy of ~0.92 kJ/l H₂S and 10% (in length) packed reactor showed the best conversion. Among the catalysts studied, MoO_x and CoO_x supported on Al₂O₃ showed high performance, which may be caused by synergy between plasma excitation of the carrier gas molecules and catalytic behaviour of MoO_x and CoO_x. Copyright © 2012 John Wiley & Sons, Ltd.

The decomposition of H₂S into H₂ and S in Al₂O₃, MoO_x/Al₂O₃, CoO_x/Al₂O₃ and NiO/Al₂O₃ packed nonthermal plasma dielectric barrier discharge (NTP-DBD) reactor was studied. The reactions were carried out with 5 mm discharge gap and 5 vol.% H₂S with 150 ml/min. Among the catalysts, MoO_x/ Al₂O₃ and CoO_x/ Al₂O₃ showed high performance because of synergy between plasma excitation of the carrier gas molecules and catalytic behaviour of the catalyst.

A novel anode catalyst layer (CL) has been prepared by ultrasonic-spray process which combines directly spraying method and catalyst-coated membrane switchover method, and heated-stereoscopic process has been used to enhance bond force between CLs and proton exchange membrane in this paper. The scanning electron microscopy, electrochemical impedance spectra and polarization curves show that: the anode outer CL with pores and meshwork structure has increased the electrochemical active surface area and retained the transfer of protons and electrons, and the anode inner CL with compact structure has prevented methanol crossover. And the gradient catalysis for methanol electrochemical catalytic oxidation reaction has been achieved. The open circuit voltage has reached 0.697 V, and the performance has increased from 116.8 mW cm⁻² of traditional membrane electrode assembly (MEA) to 202.6 mWcm⁻² of novel MEA at 80°C. Copyright © 2012 John Wiley & Sons, Ltd.

The gasification of biomass can be coupled to a downstream methanation process that produces synthetic natural gas (SNG). This enables the distribution of bioenergy in the existing natural gas grid. A process model is developed for the small-scale production of SNG with the use of the software package Aspen Plus (Aspen Technology, Inc., Burlington, MA, USA). The gasification is based on an indirect gasifier with a thermal input of 500 kW. The gasification system consists of a fluidized bed reformer and a fluidized bed combustor that are interconnected via heat pipes. The subsequent methanation is modeled by a fluidized bed reactor. Different stages of process integration between the endothermic gasification and exothermic combustion and methanation are considered. With increasing process integration, the conversion efficiency from biomass to SNG increases. A conversion efficiency from biomass to SNG of 73.9% on a lower heating value basis is feasible with the best integrated system. The SNG produced in the simulation meets the quality requirements for injection into the natural gas grid. Copyright © 2012 John Wiley & Sons, Ltd.

This paper develops a new approximate model to predict the pressure and momentum forces on a Savonius-style vertical axis wind turbine. Flow distributions through and around the turbine are examined for analytical predictions of the torque and power output, at all rotor angles. A new approximate streamtube method is developed to predict the momentum, lift, and drag forces on the rotor surfaces by the air stream on the basis of an integral force balance on the turbine blades. Unlike other past analytical methods, the technique predicts both momentum and pressure forces imposed on the rotor surface during operation. The calculated results are validated against experimental data and numerical predictions from computational fluid dynamics. Copyright © 2012 John Wiley & Sons, Ltd.

In this communication, a 50 MW_e design capacity parabolic dish Stirling engine solar power plant (PDSSPP) has been modeled for analysis, where 2000 units of parabolic dish Stirling engine each having capacity of 25 kW_e were considered to get desired capacity. An attempt has been made to carry out the energetic and exergetic analysis of different components of a solar power plant system using parabolic dish collector/receiver and Stirling engine. The energetic and exergetic losses as well as efficiencies for typical PDSSPP under the typical operating conditions have been evaluated. Variations of the efficiency of Stirling engine solar power plant at the part-load condition are considered for year-round performance evaluation. The developed model is examined at location Jodhpur (26.29°N, 73.03°E) in India. It is found that year-round energetic efficiency varies from 15.57% to 27.09%, and exergetic efficiency varies from 16.83% to 29.18%. The unit cost of electric energy generation (kW_eh) is about 8.76 Indian rupees (INR), with 30 years life span of the plant and 10% interest rate on investment. Copyright © 2012 John Wiley & Sons, Ltd.

The transient response of a proton exchange membrane fuel cell (PEMFC) with a serpentine flow field design is investigated using a three-dimensional numerical model. The simulations consider three different flow field designs with 7, 11, and 15 bends, respectively. For the flow field design with 11 bends, three different channel width ratios are considered, namely 25%, 50%, and 75%. The channel width ratio is defined as the ratio of the channel width to the total channel/rib width. The simulation results show that for all of the flow field designs, an overshoot in the local current density occurs when the voltage is reduced instantaneously from 0.7 to 0.5 V because of the high and uniform oxygen mass fraction. Conversely, a significant undershoot occurs when the voltage is increased instantaneously from 0.5 to 0.7 V because of the low and nonuniform oxygen mass fraction. The overshoot and undershoot phenomena are particularly evident in the PEMFC with a 15-bend flow field. For the flow field design with 11 bends, the channel width ratio has little effect on the current density at an operating voltage of 0.7 V. However, at an operating voltage of 0.5 V, the oxygen concentration into the catalyst and diffusion layers increases with the increasing channel width ratio, which leads to higher current density. As a result, a more significant overshoot phenomenon is observed in the flow field with a width ratio of 75%. Copyright © 2012 John Wiley & Sons, Ltd.

This paper presents a computational investigation of the effect of time-varying humidity conditions on a polymer electrolyte membrane fuel cell. The objective is to develop a better fundamental understanding of the fuel cell's performance under actual driving conditions. Such an understanding will be beneficial in improving the fuel cell design for mobile applications. The study employs a macroscopic single-fuel cell-based, one-dimensional, isothermal model. The novelty of the model is that it does not rely on the non-physical assumption of the uptake curve equilibrium between the pore vapor and ionomer water in the catalyst layers. Instead, the transition between the two phases is modeled as a finite-rate equilibration process. The modulating conditions are simulated by forcing the temporal variations in reactant humidity. The results show that reactant humidity modulations cause a departure in the cell behavior from its steady behavior, and the finite-rate equilibration between the catalyst vapor and liquid water can be a factor in determining the cell response. The cell response is also affected by the modulating frequency and amplitude. Copyright © 2012 John Wiley & Sons, Ltd.

In this study, the heat transfer performance and friction characteristics of a novel concentric tube heat exchanger with different pitches of helical turbulators were investigated experimentally and numerically for a Reynolds number range from 3000 to 14 000. An experimental system was established to obtain experimental data. The numerical simulations were performed by using a three dimensional numerical computation technique, a commercial CFD computer code. Then, the heat transfer performance and friction characteristics of several helical turbulators were compared. The experimental, numerical and empirical correlation results were in a good agreement with each others. As a result, the heat transfer enhancements using turbulators were 2.91, 2.41, 2.18 and 1.99 times better than the smooth tube for pitch distances of p = 20, 40, 60 and 80 mm, respectively. Copyright © 2012 John Wiley & Sons, Ltd.

The heat transfer performance and friction characteristics of a novel concentric tube heat exchanger with different pitches of helical turbulators were investigated experimentally and numerically. A good agreement between the experimental and numerical results and an effective enhancement of heat transfer performance were obtained using the novel helical turbulators. The new correlations for turbulent forced convection were proposed for Reynolds number range from 3 000 to 14 000.

This paper presents a dynamic model of a solid oxide fuel cell (SOFC) and its performance test under direct current (DC) and alternating current (AC) operation conditions. The proposed fuel cell model involves all voltage losses, thermal dynamics and methanol reformer. SOFC model is developed on Matlab/Simulink environment. First, DC load following capability of proposed SOFC dynamic model is examined. Then, the SOFC dynamic model is connected to single-machine infinite bus through a transmission line. To connect the proposed SOFC dynamic model to AC bus, a basic power conditioner unit (PCU) is designed. A PCU, which consists of a DC–DC boost converter, a DC–AC inverter, their controller, transformer and filter, is designed. Finally, the proposed SOFC model is also simulated for an AC power system that has sinusoidal voltage of 400 V, frequency of 50 Hz and resistive load of 200 W. The simulation results show that the proposed SOFC dynamic model has followed fairly DC load variations. Also, the output voltage of fuel cell system under maximum DC load conditions is obtained as 280 V. The designed power conditioning unit is suitable for studying AC power system applications. Copyright © 2012 John Wiley & Sons, Ltd.

The current paper describes the design of a prototype system to explore the feasibility of the adsorption thermal energy storage. Water was chosen as the adsorbate, and three different adsorbents were tested. Zeolite 13X, NaLSX zeolite, and an activated alumina (AA)/zeolite 13X composite adsorbent were used as adsorbents. Experiments were performed at varying flow rates and different relative humidities to determine the optimal operating conditions for the system. The regeneration of the adsorbents also was explored by performing repeated runs on the same adsorbent sample. The results indicate that complete regeneration was achieved. A maximum energy density of 160 kWh/m³ has been achieved with the AA/13X adsorbent, and this adsorbent was chosen for further studies. After this adsorbent screening, the system was modified to improve the data recording and system performance. Tests were performed on AA/13X, and a maximum energy density of 200 kWh/m³ was achieved, which was much higher than the maximum energy density reported in the literature for adsorption thermal energy storage systems (165 kWh/m³). Copyright © 2012 John Wiley & Sons, Ltd.

In a trigeneration plant, the thermal energy recovered from the prime mover is exploited to produce a cooling effect. Although this possibility allows the working hours of the plant to be extended over the heating period, providing summer air conditioning through thermally activated technologies, it is rather difficult to find in the literature experimental data on trigeneration plants operation, and the availability of performance characteristics at off-design conditions is anyway limited. The paper has the aim of showing the experimental data of a real trigeneration system installed at the Politecnico di Torino (Turin, Italy), composed of a natural gas 100 kW_el microturbine coupled to a liquid desiccant system. The data are presented for both cogeneration and trigeneration configurations, and for full and partial load operations.

An energetic and economic performance assessment at rated power operation is presented, and compared with the partial load operation strategy. The primary energy savings are calculated through a widely accepted methodology, proposed by the European Union, and through another methodology, reported in literature, which seems to the Authors more suitable to describe the energetic performances of trigeneration plants. Copyright © 2012 John Wiley & Sons, Ltd.

The exploitation of coal-mine methane is analysed to reduce the environmental impact from coal power systems. The analyses are based on a life cycle assessment, and the results were compared with carbon-capture and storage technologies. The results suggest that by increasing the use of coalmine methane, the environmental impacts of coal power plants could be clearly reduced. Although the CO₂ reduction is much less than through sequestration of CO₂, increased use of coal-mine methane in Poland could potentially reduce greenhouse gas emissions up to 9 million tonnes of CO₂ per year, which corresponds to about 2.5% of the emissions of Poland. Copyright © 2012 John Wiley & Sons, Ltd.

The use of reversible chemical reactions in recuperation of heat has gained significant interest due to higher magnitude of reaction heat compared to that of the latent or sensible heat. To implement chemical reactions for upgrading heat, a chemical heat pump (CHP) may be used. A CHP uses a reversible chemical reaction where the forward and the reverse reactions take place at two different temperatures, thus allowing heat to be upgraded or degraded depending on the mode of operation. In this work, an exergetic efficiency model for a CHP operating in the temperature-level amplification mode has been developed. The first law and the exergetic efficiencies are compared for two working pairs, namely, CaO/CO₂ and CaO/H₂O for high-temperature high-lift CHPs. The exergetic efficiency increases for both working pairs with increase in task, T_H, decrease in heat source, T_M, and increase in condenser, T_L, temperatures. It is also observed that the difference in reaction enthalpies and specific heats of the involving reactants affects the extent of increase or decrease in the exergetic efficiency of the CHP operating for temperature-level amplification. Copyright © 2012 John Wiley & Sons, Ltd.

A chemical heat pump (CHP) uses a reversible chemical reaction to upgrade or degrade heat depending on the mode of operation. An exergetic efficiency model for a CHP operating in the temperature-level amplification mode has been developed. The exergetic efficiency increases with increase in task, T_H, decrease in heat source, T_M, and increase in condenser, T_L, temperatures.

This paper performs a thermodynamic analysis of a modified dual photo-electrochemical cell for water electrolysis, previously developed by Grätzel. In a typical Grätzel cell, a semi-transparent photo-electrode is used in conjunction with a dye photo-sensitized cell to generate a bias voltage necessary to overcome the inherent over-potentials caused by irreversibilities within the cell. The modified method implements hybrid photo-catalysis instead of heterogeneous catalysis. In the hybrid photo-catalysis approach, both homogeneous and heterogeneous photo-catalysts are used to enhance the speed of the water splitting reaction and to widen the portion of the solar radiation spectrum for the process. The dual cell consists of two tandem units. The first unit is a photo-electrolysis cell exposed to solar radiation (at both cathodic and anodic sides) via a transparent window, whereas the second unit is a dye-sensitized solar cell, which assists the photo-electrolysis cell. In the cathodic solution, there are dissolved Brewer-type supra-molecular complexes for photo-catalytic water reduction to generate hydrogen. They absorb solar radiation in the upper visible spectrum and dislocate multiple electrons at the active center. The complexes accept electrons donated from a GaP-based semi-transparent photo-cathode. The remaining un-absorbed radiation (mainly in the infrared range) crosses the semitransparent counter-electrode and the back glass. It is absorbed by a solar thermal collector for enhancing the solar radiation utilization by co-generating low-grade heat. The tandem cell with hybrid photo-catalysis has promising potential of improved solar radiation utilization. This paper analyzes the system efficiency and shows that 4% energy efficiency can be obtained for hydrogen generation. About 20% of the incident solar spectrum can be captured by the cell and used for hydrogen generation. Around 60% of solar radiation is recovered in the form of heat on a flat plate solar thermal collector placed behind the cell. The influence of catalyst concentration and pH also is studied. The device forms a four-gap solar absorber system, which is coupled to a cogeneration sub-system for heating, so the solar energy utilization is maximized. The four-gap system absorbs photons at 1.6, 2.1, 2.3, and 2.7 eV and generates five reversible potentials of 0.42, 0.9, 1.6, 2.1, and 2.3 V. Based on the predicted results, the reaction rate appears to be enhanced with respect to other solar electrolysis cells (such as photo-electrolyzers and a dual photo-electrochemical cell) because homogeneous catalysis enhances the electrode kinetics. Copyright © 2012 John Wiley & Sons, Ltd.

As an open and demanding problem, accurate modeling of polarization curve in proton exchange membrane fuel cell has become the main issue of various researches. In recent years, because of their great potentials, metaheuristic optimization algorithms have represented good performances in identification of the unknown parameters of the proton exchange membrane fuel cell model, but there is the possibility to obtain more accurate results with more capable algorithms. In the literature, many heuristic optimization algorithms have been developed on the basis of natural phenomena. However, there are still some possibilities to devise new ones. In this paper, evolution of bird species has been regarded, and the intelligent behavior of birds during mating season has become an inspiration to devise a new heuristic optimization algorithm, named bird mating optimizer. Moreover, in this paper, the whole unknown parameters of the model, even dimensional parameters, are included in the identification process. The proposed algorithm is used to model the Ballard Mark V FC, and its performance is compared with those of the recently published paper by the authors. Simulation results reveal the superior performance of bird mating optimizer algorithm. Copyright © 2012 John Wiley & Sons, Ltd.

Bagasse is selected as the biomass source that is studied because of its annual significant rate production in Iran and potential for energy generation. Bagasse has been as an energy source for the production of energy required to run the sugar factory. The energy needed by factories was supplied by burning bagasse directly inside furnaces, which had an exceptionally low output. To this end, today, a secondary use for this waste product is in combined heat and power plants where its use as a fuel source provides both heat and power. In addition, low efficiency of traditional methods was caused to increase the use of modern methods such as anaerobic digestion, gasification and pyrolysis for the production of bio-fuels. In this paper, the energy conversion technologies are compared and ranked for the first time in Iran. Therefore, the most fundamental innovation of this research is the choice of the best energy conversion technology for the fuel production with a higher efficiency.

To assess the feasibility application and economic benefit of biogas CHP plant, a design for a typical biogas unit is programmed. The results show the acceptable payback period; therefore, economically and technically, biogas CHP plant appears to be an attractive proposition in Iran. Copyright © 2012 John Wiley & Sons, Ltd.

In the present work, catalytic cracking of fish oil industrial residue was investigated to study the effect of temperature, type of catalyst and the heating rate on the yield of organic liquid fraction (OLF) and its acid value. The highest bio-oil yield of 72% (wt.) was obtained at temperature range of 300–500 °C and heating rate of 10 °C/min with the mixture of Al₂O₃ and Na₂CO₃ as a catalyst. It was found that the mixture of Na₂CO₃ and MgSO₄ as a catalyst gives lowest acid value of 8.75 mg_KOH/g_oil and 68.1% of OLF yield. Furthermore, the acid value is reduced to 0.36 mg_KOH/g_oil using Na₂CO₃ as an absorbent. The results show that the catalytic cracking process represents a sustainable method to produce bio-oil from fish oil industrial residues with physicochemical characteristics similar to the diesel fuel. Copyright © 2012 John Wiley & Sons, Ltd.

The present work is to derive the biofuel from fish oil industrial residues by catalytic thermal cracking. To evaluate the higher biofuel yield with low acid value, the operating conditions of temperature range and heating rate with different catalysts were optimized. The lowest acid value of 8.75 mg_KOH/g_oil with the biofuel yield of 68.1 % was derived with a heating rate of 10° C/min at the cracking temperature of 500 °C using Na₂CO₃/MgSO4 as catalyst. It is further reduced to 0.36 mg_KOH/g_oil using Na₂CO₃ as an absorbent.

Reunion Island is heavily dependent on fossil fuels, but seeks to become energy self-sufficient by 2025. ocean thermal energy conversion provides a means of producing electricity that harnesses the available energy of the ocean by using the temperature gradient between its deep and its upper layers. This paper presents the projected experimental facility which is to be installed at the University of St. Pierre on Reunion Island. A dynamic model of the installation has been developed (on a Delphi interface) by using the concept of equivalent Gibbs systems. In such equivalent system, mass, energy, and entropy are linked through the Gibbs equation, and the entropy production can easily be expressed in terms of fluxes and their related forces. Assuming linear phenomenological laws, the phenomenological coefficients are assessed from technical data. Using a digital tool (Genopt), an optimization study has been conducted in order to determine the best operating parameters according to the temperature of the sea water. This model allows us to anticipate the potential of this technology on Reunion Island. Once validated on the facility, the model will serve as a tool to assist design of the future 10 MW pilot plant planned for 2014. Copyright © 2012 John Wiley & Sons, Ltd.

This paper compares different energy-related investment options that can be implemented in a kraft pulp mill with a potential steam surplus. The options investigated include lignin extraction, electricity production, capturing of CO₂ and black liquor gasification with production of electricity or biofuels, here DME. The investment options are compared with respect to annual net profit and global CO₂ emissions for different future energy market scenarios. A further analysis of how different parameters such as policy instruments and investment costs affect the different technologies also is included. The results show that, generally, for reasonable levels of biofuel support, the best economic performance among the studied technologies is achieved by extraction of lignin valued as oil. However, if the level of support for biofuels is high, black liquor gasification with DME production generally has the best economic performance among the studied options. All the investment options investigated decrease global CO₂ emissions significantly. Capturing and storing CO₂ from the recovery boiler flue gases result in the highest CO₂ emissions reduction and also is an economically attractive option in scenarios with a high CO₂ emissions charge. Copyright © 2012 John Wiley & Sons, Ltd.

Among the renewable energy types, wind provides intermittent but environmentally friendly energy source that does not pollute atmosphere. Wind power calculations are initiated from the kinetic energy definition, and finally, the power is found as proportional to the half (1/2) of air density multiplied by the wind velocity cube. In this paper, wind power formulation is derived first by use of kinetic energy definition and then the basic physical definitions of power as the ratio of work per time, the work as the force multiplied by the distance and the force as the change of momentum. These considerations lead to wind power formulation with 1/3 factor instead of 1/2. Furthermore, formulation with factor of 1/3 gives results close to Betz limit within 10% difference at very high wind speeds (> 12 m/s), which remains within practically acceptable limits. Copyright © 2012 John Wiley & Sons, Ltd.

Quantifying the severity of the intermittencies in solar irradiation is important for (i) understanding the potential impacts of high solar power penetration levels on the electric grid and (ii) evaluating the need for technologies that may be necessary to complement solar power in order to balance the electric grid. This study uses a spectral method to distinguish between cloud-induced and diurnal cycle-induced transients and to quantify the severity of intermittencies occurring over a range of timescales. The method is used to quantify variability between specific sites as well as to evaluate the sensitivity of solar power variability to spatial diversification of the solar farm portfolio. Results indicate that increasing the spatial diversity of the solar farm portfolio reduces the magnitude of the fluctuations in power output as a fraction of the total system capacity. This behavior is associated with two forces: (i) a reduction in the influence of fluctuations occurring at an individual site on the total profile and (ii) should the sites in question be sufficiently spaced apart, the fluctuations in solar irradiation that each site exhibits are uncorrelated and do not generally add up in tandem at short timescales. These effects reduce the degree of uncertainty and variability associated with solar farm output and demonstrate a reduction in the maximum magnitude of solar power fluctuations for a given solar penetration level. The rate of increase of the maximum solar power deviation from the 1-h average associated with increases in desired solar penetration level decreases in an inverse exponential manner with the number of sufficiently spaced sites composing the solar farm portfolio. These results imply that a lower amount of regulation or energy storage capacity is needed to regulate solar intermittency if solar installations and the accommodating transmission infrastructure are designed and operated appropriately. Copyright © 2012 John Wiley & Sons, Ltd.

Passive direct methanol fuel cells (DMFCs) are under development for use in portable applications because of their enhanced energy density in comparison with other fuel cell types. The most significant obstacles for DMFC development are methanol and water crossover because methanol diffuses through the membrane generating heat but no power. The presence of a large amount of water floods the cathode and reduces cell performance. The present study was carried out to understand the performance of passive DMFCs, focused on the water crossover through the membrane from the anode to the cathode side. The water crossover behaviour in passive DMFCs was studied analytically with the results of a developed model for passive DMFCs. The model was validated with an in-house designed passive DMFC. The effect of methanol concentration, membrane thickness, gas diffusion layer material and thickness and catalyst loading on fuel cell performance and water crossover is presented. Water crossover was lowered with reduction on methanol concentration, reduction of membrane thickness and increase on anode diffusion layer thickness and anode and cathode catalyst layer thickness. It was found that these conditions also reduced methanol crossover rate. A membrane electrode assembly was proposed to achieve low methanol and water crossover and high power density, operating at high methanol concentrations. The results presented provide very useful and actual information for future passive DMFC systems using high concentration or pure methanol. Copyright © 2012 John Wiley & Sons, Ltd.

In this work, a thermally coupled membrane reactor is proposed for methane steam reforming and hydrogenation of nitrobenzene. The steam reforming process is carried out in the assisted membrane surface of the endothermic side, while the hydrogenation reaction of nitrobenzene to aniline is carried out on the other membrane surface of the exothermic side. The differential evolution (DE) strategy is applied to optimize this reactor considering nitrobenzene and methane conversion as the main objectives. The co-current mode is investigated in this study, and the achieved optimization results are compared with those of conventional steam reformer reactor operated under the same feed conditions. The optimum values of feed temperature of exothermic side, feed molar flow rate of nitrobenzene, the steam-to-nitrobenzene molar ratio and the hydrogen-to-nitrobenzene molar ratio are determined during the optimization process. The simulation results show that the methane conversion and consequently hydrogen recovery yield are increased by 39.3% and 1.57, respectively, which contribute to aniline production with 27.3% saving in hydrogen supply from external and a reduction in environmental problems due to 100% nitrobenzene conversion. The optimization results justify the feasibility of coupling these reactions. Experimental proof-of-concept is needed to establish the validity and safe operation of the novel reactor. Copyright © 2012 John Wiley & Sons, Ltd.

Energy demand is increasing rapidly because of developments in the agricultural, industrial, commercial and transportation sectors. Improved lifestyle and population rise are other reasons for the increase in energy demand. The development of an electricity allocation model will help in the proper allocation of the energy sources to meet the future electricity demand in India. In this paper, an attempt has been made to develop a fuzzy-based linear programming, optimal electricity allocation model (OEAM) that minimizes the cost and determines the optimum allocation of different energy sources to the centralized and decentralized power generation in India. The potential of energy sources, energy demand, efficiency of the energy systems, emission released by the energy systems and carbon tax for the emissions released by each system are the main factors that influence the pattern of electricity distribution and are used as constraints in the model. Executing this model results in an optimal electricity distribution pattern. The results indicate that the commercial energy sources such as coal, nuclear and hydro would meet nearly 68% of total electricity demand and that the remaining 32% of the electricity demand will be met by the renewable energy sources, namely, wind, biomass, biogas, solid waste, cogeneration and mini hydel for the year 2020. Various scenarios are also developed by varying the demand, potential, emission and carbon tax. This study will help in the formation of strategies for effective utilization of energy sources in India. Copyright © 2012 John Wiley & Sons, Ltd.

The assessment for realistic CO₂-adsorption capacities of different rocks is important for understanding the processes associated with CO₂ storage. This paper investigates the adsorption characteristics of rocks for CO₂ (limestone, sandstone, marl, claystone, clay, siltstone and metamorphic rock) by using a gravimetric method. The measurements were performed at 21°C with pressures from 1 up to 4 MPa. Sandstone (and clay with sand/sandstone) showed the largest adsorption capacity at 21°C. The highest amount of in situ CO₂ contents in measured samples was 21.4 kg/t. The CO₂-adsorption capacities were lower than past results in different coal samples. The results indicate that adsorption of CO₂ into rocks may play an important role in storing CO₂ in subsurface rock. Copyright © 2012 John Wiley & Sons, Ltd.

Economic, environmental and social pressures have increased the need for business organisations to control and manage their energy performance on a continual basis. Responding to these pressures follows a learning curve that is influenced by changing drivers and barriers. Consequently, different energy management factors have different development priorities over time. This paper explores the development priority of one factor, namely, energy performance measurement, in the energy-intensive industrial sector, which is the most advanced industrial sector in its energy management learning curve. In addition, the paper identifies the research and development needs of energy performance measurement that are required to further improve energy performance. The results are based on interviews carried out with managers and operators in three energy-intensive industrial sectors in Finland. Energy performance measurement is found to be the third development priority in energy management, behind resource and commitment issues. This represents a paradox as resources and commitment are prerequisites for energy performance measurement to be developed, whereas energy performance measurement influences the very same issues by enforcing changed behaviour. Several deficiencies are identified in energy performance measurement in the temporal, systemic and organisational dimensions. Research should be continued towards the implementation of energy performance measurement as a process, the integration of energy performance metrics into overall management and the development of metrics for different industrial sectors, companies and operating cultures. Copyright © 2012 John Wiley & Sons, Ltd.

Energy-intensive industries have followed a learning curve in energy management. This paper identifies energy performance measurement as the third development priority of energy management, behind resource and commitment issues. Only by overcoming the found information gaps, energy performance can become a true organisational goal across all organisational levels and management functions.

Increased atmospheric CO₂ concentration is widely being considered as the main driving factor that causes the phenomenon of global warming, due to the ever-boosting use of fossil fuels. In this study, a fuzzy-stochastic programming model with soft constraints (FSP-SC) is developed for electricity generation planning and greenhouse gas (GHG) abatement in an environment with imprecise and probabilistic information. The developed FSP-SC is applied to a case study of long-term planning of a regional electricity generation system, where integer programming technique is employed to facilitate dynamic analysis for capacity expansion within a multi-period context to satisfy increasing electricity demand. The results indicate different relaxation levels can lead to changed electricity generation options, capacity expansion schemes, system costs, and GHG emissions. Several sensitivity analyses are also conducted to demonstrate that relaxation of different constraints have different effects on system cost and GHG emission. Tradeoffs among system costs, resource availabilities, GHG emissions, and electricity-shortage risks can also be tackled with the relaxation levels for the objective and constraints. Copyright © 2012 John Wiley & Sons, Ltd.

Among various developed methods for CO₂ capturing from industrial flue gases, chemical absorption system is still considered as the most efficient technique, because of its lower energy requirement and also its applicability for low concentration of CO₂ in the inlet gas stream. Also, it can be used to retrofit the existed power plants, which are the major industrial CO₂ emission sources, without changing their design condition. Selection of a suitable solvent is the first parameter that should be considered in the design of capture plants that use absorption technology. The most important challenge for using chemical solvents is finding the optimum operating conditions to minimize the energy requirement. Study of technical parameters can be helpful to improve the overall capture plant efficiency. In this paper, CO₂ capture plant has been simulated for different solvents to compare their performance and energy requirement. To improve the plant overall efficiency, effect of the main operating factors such as amine flow rate, temperature, inlet gas temperature, and pressure has been studied in this paper. This analysis indicates the best chemical solvent for various cases of inlet flue gas. This parametric study reduces the overall energy requirement and helps design a cost-effective plant. Copyright © 2012 John Wiley & Sons, Ltd.

TiO₂ nanopowders are synthesized using a hydrothermal process under various conditions. Effects of several hydrothermal conditions are investigated such that the TiO₂ nanopowders having optimized size, surface area, crystallinity, and yield are used for the fabrication of photoanodes. The obtained TiO₂ photoanodes are subjected to oxygen plasma treatments for various times. As-synthesized and plasma-treated photoanodes are then assembled into dye-sensitized solar cells. The plasma-treated photoanodes exhibit different concentrations of surface C–OH and oxygen vacancies, depending on the plasma treatment times. This leads to dye-sensitized solar cells having different conversion efficiencies. The use of plasma treatment can enhance the cell conversion efficiency by more than 24%. The effects of the photoanode surface condition on the performance of photoanode are discussed. Copyright © 2012 John Wiley & Sons, Ltd.

The paper deals with thermodynamic analysis of cooled gas turbine-based gas-steam combined cycle with single, dual, or triple pressure bottoming cycle configuration. The cooled gas turbine analyzed here uses air as blade coolant. Component-wise non-dimensionalized exergy destruction of the bottoming cycle has been quantified with the objective to identify the major sources of exergy destruction. The mass of steam generated in different configurations of heat recovery steam generator (HRSG) depends upon the number of steam pressure drums, desired pressure level, and steam temperature. For the selected set of operating parameters, maximum steam has been observed to be generated in the case of triple pressure HRSG = 19 kg/kg and minimum in single pressure HRSG = 17.25 kg/kg. Plant-efficiency and plant-specific works are both highest for triple-pressure bottoming cycle combined cycle. Non-dimensionalized exergy destruction in HRSG is least at 0.9% for B3P, whereas 1.23% for B2P, and highest at 3.2% for B1P illustrating that process irreversibility is least in the case of B3P and highest in B1P. Copyright © 2012 John Wiley & Sons, Ltd.

Component-wise exergy destruction in heat recovery steam generator (HRSG) is lowest for B3P (0.9%) followed by B2P (1.23%) and B1P (3.2%) as a result of reduction of irreversibility associated with heat transfer in HRSG due to increase in number of pinch points with increase in number of HRSG pressure levels that leads to the decrease in temperature of heat transfer.

A thermal-economic analysis of a transcritical Rankine power cycle with reheat enhancement using a low-grade industrial waste heat is presented. Under the identical operating conditions, the reheat cycle is compared to the non-reheat baseline cycle with respect to the specific net power output, the thermal efficiency, the heat exchanger area, and the total capital costs of the systems. Detailed parametric effects are investigated in order to maximize the cycle performance and minimize the system unit cost per net work output. The main results show that the value of the optimum reheat pressure maximizing the specific net work output is approximately equal to the one that causes the same expansion ratio across each stage turbine. Relative performance improvement by reheat process over the baseline is augmented with an increase of the high pressure but a decrease of the turbine inlet temperature. Enhancement for the specific net work output is more significant than that for the thermal efficiency under each condition, because total heat input is increased in the reheat cycle for the reheat process. The economic analysis reveals that the respective optimal high pressures minimizing the unit heat exchanger area and system cost are much lower than that maximizing the energy performance. The comparative analysis identifies the range of operating conditions when the proposed reheat cycle is more cost effective than the baseline. Copyright © 2012 John Wiley & Sons, Ltd.

Drying is a high-energy-intensive operation and an important step in the pasta production. In this study, exergy analysis of a four-step drying system in a farfalle pasta production line using actual operational data obtained from a plant located in Izmir, Turkey, was performed. Exergy loss rates, evaporation rates, exergy efficiencies, and improvement in potential rates for each dryer section were determined in this drying system. The exergy efficiency values varied between 0.25% and 5.27% from the predrying to the final drying section. The exergy efficiency value for the entire drying system was calculated to be 2.96%, and the highest exergetic improvement in potential rate was 165.54 kW for the first dryer section. Copyright © 2012 John Wiley & Sons, Ltd.

A four-step drying system in a farfalle pasta production line was exergetically analyzed for assessing and improving the efficiency of the drying process and the entire system along with its main components. Actual operational data were used in the analysis. The exergy efficiency values varied between 0.25% and 5.27% from the predrying to the final drying section, being 2.96% for the entire drying system. The highest exergetic improvement in potential rate (IP) was 165.54 kW for the first dryer section.

Well-ordered Nafion-silica-HPW proton exchange membranes with Nafion ionomers as co-surfactant have been synthesized through a facile self-assembly between the positively charged silica, negatively charged HPW acids, and Nafion ionomers. The results exhibited uniform nanoarrays with long-range order when Nafion content in the complex is lower than 30 wt%. The electrolyte stripe textures were clearly presented with an interval channel of 5–6 nm. The well-ordered proton conducting sites made the proton move through the membrane freely with low humidity dependence of proton transportation through the Nafion-silica-HPW electrolyte. The proton conductivities of the Nafion-silica-HPW electrolyte with Nafion content of 10–30 wt% were 0.018–0.022 Scm⁻¹ at 25 °C without humidification, and the conductivities increased to 0.043–0.05 Scm⁻¹ when the temperature increased to 200 °C. The capillary condensation of the ordered structure also improved the water uptake of the Nafion-silica-HPW electrolyte at low humidity. With external humidifying of 25 RH%, the water uptake of the Nafion-silica-HPW electrolyte with Nafion content of 10–30 wt% reached to 15–23 wt% at elevated temperature of 100–200 °C. The improvement of the water uptake facilitated proton transport through the Nafion-silica-HPW electrolytes, resulting in proton conductivities of 0.082–0.095 Scm⁻¹ at temperature of 150–200 °C, 25 RH%. Copyright © 2012 John Wiley & Sons, Ltd.

This article examines the exhaust waste heat recovery potential of a microturbine (MT) using an organic Rankine cycle (ORC). Possible improvements in electric and exergy efficiencies as well as specific emissions by recovering waste heat from the MT exhaust gases are determined. Different dry organic working fluids are considered during the evaluation (R113, R123, R245fa, and R236fa). In general, it has been found that the use of an ORC to recover waste heat from MTs improves the combined electric and exergy efficiencies for all the evaluated fluids, obtaining increases of an average of 27% when the ORC was operated using R113 as the working fluid. It has also been found that higher ORC evaporator effectiveness values correspond to lower pinch point temperature differences and higher exergy efficiencies. Three different MT sizes were evaluated, and the results indicate that the energetic and exergetic performance as well as the reduction of specific emissions of a combined MT-ORC is better for small MT power outputs than for larger MTs. This article also shows how the electric efficiency can be used to ascertain under which circumstances the use of a combined MT-ORC will result in better cost, primary energy consumption, or emission reduction when compared with buying electricity directly from electric utilities. Copyright © 2012 John Wiley & Sons, Ltd.

The hydrogen storage properties of Ti_1−xSc_xMnCr (x = 0.05, 0.10, 0.15, 0.22, 0.27 and 0.32) alloys are studied by pressure-composition isotherms at 0–60 °C and 1 kPa–4 MPa. The relevant crystal structures of the alloys and their hydrides are examined by the X-ray diffraction and electron microscopy. The alloys are basically C14 type Laves phase with slightly different lattice parameters owing to the difference in composition. Except for x = 0.05 alloy, the bulk samples of these alloys can be easily activated under ambient conditions and attain the maximum hydrogen storage capacities during the initial hydrogenation. As Sc content increases, the hydrogen storage capacity of the alloy increases whereas the pressure of the absorption/desorption plateau decreases. No hydrogen-induced disproportionation is observed, and the hydrogen-induced defects and pulverization are not severe after hydriding/dehydriding cycles of these alloys. The Ti_0.78Sc_0.22MnCr alloy exhibits the best reversible hydrogen storage capacity of ~2 wt% in between 1 and 4000 kPa at room temperature. Except for the x = 0.32 alloy, the average thermodynamic values of |ΔH| and |ΔS| in the system increase approximately linearly with Sc content in the alloys. The thermogravimetry-differential scanning calorimetry (TG-DSC) on desorption of the hydride of Ti_0.68Sc_0.32MnCr indicates that the thorough release of hydrogen in the alloy can be achieved at 658 K. Copyright © 2012 John Wiley & Sons, Ltd.

Laves phase Ti_1-xSc_xCrMn (x ≥ 0.1) alloys can be easily activated at sub-atmosphere and room temperature. Ti_0.78Sc_0.22MnCr alloy exhibits a ∼ 2 wt% reversible hydrogen storage capacity at 1 kPa-4 MPa and 293 K. Average ΔH of hydride formation of the Ti_1-xSc_xCrMn alloys locates in the range of -17 – -33 kJ/molH₂.

The experimental investigation of TiFe-hydride has been performed for rapid and high-rate storage of hydrogen under low operating pressure. Three different reactors are designed, manufactured and tested to investigate the effect of reactor design. The reactors are a tubular-shaped simple one, a tubular-shaped reactor with fins and a tubular-shaped reactor with liquid cooling channels. All of the reactors are filled with same amount of TiFe alloy and charged under various hydrogen supply pressures. The charging time and the role of the heat transfer mechanism are investigated by obtaining temperature histories which are measured at several points on the reactors. It has been found that the reactor design and activation process of metal-hydride alloy are significant parameters on the amount of hydrogen stored in the reactor and the elapsed time for storing. The charging time was 84% less, and storage rate was 39% higher for Reactor-3 compared to Reactor-1. The hydrogen storage rate was approximately 0.44% which is achieved at relatively low charging pressure of 12 bar. Copyright © 2012 John Wiley & Sons, Ltd.

In this study, three different TiFe-hydride reactors which are simple bare one, the one with cooling fins and the one with water cooling are designed and manufactured to investigate the effect of reactor design on the hydrogen storage rate and time at low pressures. The temperature variations and hydrogen storage rates of the reactors are investigated for the charging process and storage rates (H/M) of 3.13g/kg, 3.31g/kg and 4.35g/kg are obtained at 12 bar pressure respectively. Since the Reactor-3 has the maximum heat transfer, it has the maximum hydrogen storage rate in shortest time period.

Magnesium – nickel alloys have been considered an alternative for AB₅ and AB₂-type alloys in nickel–metal hydride batteries due to their larger maximum discharge capacities, but their low stability in alkaline solution has hindered their use in commercial cells. Aiming to improve the electrode performance of the Mg₅₅Ni₄₅ alloy, we investigated the simultaneous addition of Ti and a noble metal (Pd and Pt) as alloying elements. The investigated system has general composition Mg₄₉Ti₆Ni_(45-x)M_x, where M is Pd or Pt, and x assumed values of 0, 2.0 and 4.0 at.%. The electrochemical measurements showed that the Mg₄₉Ti₆Ni₄₁Pd₄ alloy has the best electrode performance among the studied alloys, reaching 431 mA h g⁻¹ of maximum discharge capacity at the first cycle of charge/discharge. After 10 and 20 cycles, this alloy presented relative discharge capacities of 84 and 77% of the initial one, respectively. The electrode performance of the investigated alloys is discussed in light of results of structural characterization by transmission electron microscopy and X-ray diffraction. Copyright © 2013 John Wiley & Sons, Ltd.

In this manuscript, the synthesis and characterization of a new alloy electrode family Mg₄₉Ti₆Ni_(45-x)M_x (M = Pd and Pt) are reported. The Mg₄₉Ti₆Ni₄₁Pd₄ alloy achieved the best electrode performance among the investigated ones. The enhanced electrode performances displayed by these alloys are explained based on their microstructural features.

TiCl₃ has been considered as the best catalyst for the hydrogen desorption/re-absorption of NaAlH₄ in terms of kinetic enhancement. However, the formation of NaCl as a by-product leads to the decrease in the reversible hydrogen capacity of NaAlH₄. In this work, TiO₂ and metallic Ti were selected as catalysts for the reaction to avoid the formation of the by-product. The comparison of the catalytic activity of Ti, TiCl₃, TiO₂ and Ti(OBu)₄ on the hydrogen desorption/absorption NaAlH₄ were carried out. It was found that TiO₂ doped NaAlH₄ exhibits similar behavior as TiCl₃ doped NaAlH₄ with the reversible hydrogen capacity about 3.8 wt% (H/M). In addition, TiO₂ doped NaAlH₄ exhibits the superior hydrogen re-absorption rate to the one doped with TiCl₃. That may be due to the Ti³⁺ defect sites on the surface of TiO₂ would facilitate the hydrogen dissociation. Moreover, high surface area of TiO₂ prevents the segregation and the morphological change of the desorbed substances (NaH and Al). This benefits to the mass transfer into the hydride system. However, doping with TiO₂ also produces sodium oxide and hydroxide as by-products. Unexpectedly, metallic Ti doped NaAlH₄ shows the lowest hydrogen desorption/re-absorption among the tested samples. Its hydrogen reversible capacity is around 1 wt% (H/M). The formation of TiH_x (1 < x < 2) was detected in the sample after the hydrogen desorption/reabsorption. Copyright © 2011 John Wiley & Sons, Ltd.

Ball-milled hydrogenated graphite-iron materials have attracted interest as possible hydrogen storage media because of theoretically estimated hydrogen capacities of about 10 wt%. However, such a value needs to be experimentally verified. In this work, graphite-0.5 wt% Fe was milled under 3 bar hydrogen in a tungsten carbide milling pot. The effect of iron on the microstructure and hydrogen storage properties of milled graphite was investigated by thermal gravimetric analysis–mass spectrometry, X-ray diffraction, and transmission electron microscopy. When a 10-hour milled graphite with 0.5 wt% Fe sample was heated under argon to 990 °C, 9.6 wt% of hydrogen was released, which is almost double than that for a graphite sample with no iron (5.5 wt% hydrogen). The addition of iron also was found to reduce the onset temperature of hydrogen desorption by 50 to 350 °C. However, for a longer milling time of 40 hours, the amount of hydrogen desorbed for graphite-0.5 wt% Fe decreased, and methane also was detected. The results suggest that iron carbide produced during milling plays a catalytic role, increasing the hydrogen storage capacity and lowering the onset temperature of hydrogen desorption. Copyright © 2011 John Wiley & Sons, Ltd.

Mg₁₇Ni_1.5Ce_0.5/5 wt.% Graphite was synthesized by microwave sintering in the present work. Its pressure-composition-isotherm curves exhibit two plateaus corresponding to MgH₂ and Mg₂NiH₄ from 563 K to 623 K, and the hydrogen storage capacity is about 5.6 wt.% at 593 K. Differential scanning calorimeter results reveal that its onset temperature and activation energy of desorption are 654.6 K and 107.41 kJ/mol, respectively, which are lower than those of MgH₂. Its rate-controlling step of the dehydriding reaction is the diffusion of hydrogen at lower temperature according to Chou model. As the catalyst and microwave absorbing agent, the addition of graphite is in favor of improving the hydrogen storage properties of the sample. Copyright © 2012 John Wiley & Sons, Ltd.

Three porous organic polymers (POPs) containing carborane were successfully synthesized as adsorbents for gas storage applications, particularly for hydrogen storage. The current physisorption-based materials generally suffer from low isosteric heat of adsorption toward hydrogen molecules. To enhance the interaction between the adsorbent hydrogen, we prepared a series of POPs containing highly electron-deficient carborane components. These polymers have narrow pore size distribution with majority of the dimensions falling in the 0.7- to 1.0-nm range. High Brunauer-Emmett-Teller (BET)-specific surface areas up to 1023 m²/g were obtained. Hydrogen adsorption capacities at 77, 195, and 298 K were measured using a Sievert isotherm apparatus. The initial heat of adsorption for the carborane -containing polymers was calculated to be 8–10 kJ/mol. Copyright © 2011 John Wiley & Sons, Ltd.

Hydrogen is a promising energy source for the future economy due to its environmental friendliness. One of the important obstacles for the utilization of hydrogen as a fuel source for applications such as fuel cells is the storage of hydrogen. Hydrogen has high gravimetric energy content but low volumetric energy density. It is desired to increase the volumetric energy density of hydrogen in a system to satisfy various applications. Adsorption of hydrogen on sorbents has been investigated. However, the weak interaction force between hydrogen molecules and the sorbents has resulted in low adsorption capacity. In this study, charge was introduced into the system. Several sorbents were investigated. The effects of charge on adsorption enhancement were determined. When NiO was embedded in a PMN-PT piezoelectric material, hydrogen adsorption increased from 0.08 to 0.11 wt% at 135 bar. For the activated carbon sorbent, hydrogen adsorption increased with both the increase in the applied voltage and the increase in the pressure. At 83 bar, the adsorption capacity increases from 0.45 wt% at 0 V to 0.46, 0.49, 0.53, and 0.55 wt% at 500, 1000, 2000 and 3000 V, respectively. Preliminary modeling was carried out to explain the enhancement of adsorption. Modeling was conducted using the B3LYP/6-31G(d) method in the GAUSSIAN 03 software program. The results show that when the electrical field is applied, the hydrogen molecules are more perturbed and attracted closer to the nickel atom, indicating a stronger interaction. The effects increase consistently with the increasing electrical field strength. NiO is a dielectric material. The adsorption enhancement is through the polarization of the compound, which is represented by the Mulliken charge. Carbon is a conductive material. It receives charges on its surface. Although the charges on the sorbents are obtained through different mechanisms, enhancements are found for both materials. Copyright © 2011 John Wiley & Sons, Ltd.

Chromium-based metal-organic framework (MOF), MIL-101(Cr), has emerged as a potential hydrogen storage material because of its high specific surface area, tuneable pore size, and unique structure. A large portion of voids generated in MOFs remain unutilized for hydrogen storage owing to weak interactions between the walls of MOFs and H₂ molecules. The present study was aimed to reduce the unutilized voids in MIL-101 by incorporating microporous activated carbon (AC) into MIL-101 pores and thereby enhancing its volumetric hydrogen storage capacity. MIL-101 and its AC composites were synthesized under hydrothermal conditions by adding AC in different proportions in situ during the synthesis of MIL-101. The synthesized materials were characterized by various physico-chemical methods such as powder X-ray diffraction, thermogravimetric analysis (TGA), N₂-adsorption/desorption isotherms measured at 77.4 K, and transmission electron microscopy (TEM). AC@MIL-101/A prepared by the incorporation of 0.63 wt% of AC into MIL-101 shows the highest hydrogen uptake of 10.1 wt% at 77.4 K and up to 6000 kPa hydrogen pressure. Copyright © 2011 John Wiley & Sons, Ltd.

A porous silicon (pSi) wafer with a hierarchical, nanoporous architecture and pure single wall carbon nanotubes (SWNTs) have been combined by electrophoretic infiltration to form a unique hybrid pSi-SWNT hydrogen storage system. The pSi architecture was fabricated by anodic etching of silicon wafers in alcoholic solutions of hydrogen fluoride. Direct hydrogen dosing to adsorb hydrogen on the pSi-SWNT hybrid, pure pSi, electrochemically charged pSi and SWNTs, and pure SWNTs, followed by temperature programmed desorption measurements, were used to quantify the hydrogen adsorption process. The results indicate an increased hydrogen storage capacity at a lower temperature in the pSi-SWNT system relative to that from pure pSi, and pure and charged SWNTs. In addition, hydrogen adsorption in pSi-SWNT is about a factor of 2 to 6 higher than that in pure and charged pSi, and pure and charged SWNTs. Copyright © 2012 John Wiley & Sons, Ltd.

A porous silicon (pSi) wafer with a hierarchical, nanoporous architecture and pure single wall carbon nanotubes (SWNTs) have been combined by electrophoretic infiltration to form a unique hybrid pSi-SWNT hydrogen storage system. Synergistic effects are observed for hydrogen storage from the hierarchical nanoporous Si and pure SWNTs architecture. By combining p-Si and SWNT, a higher hydrogen storage capacity and a lower desorption temperatures are achieved, compared to their parent materials, pure p-Si and SWNT.

The purpose of this study is to optimize the design of a composite laminate hydrogen storage vessel for minimizing stress concentration. The optimum design of this study uses the finite-element method combined with a simplified conjugated gradient method (SCGM) and genetic algorithm (GA) to find the minimization of von Mises stress of the composite laminate hydrogen storage vessel. In this study, a composite laminate hydrogen storage vessel with an aluminum liner and a carbon fiber/epoxy layer are considered. The winding angle and thickness of the composite layer are proposed as optimal design variables. The comparison between SCGM and GA is discussed in order to obtain a promising optimum in design process. Through this optimization, the best possible combination of winding angle and thickness of composite layer has been obtained to obtain minimum possible stress concentration. Copyright © 2012 John Wiley & Sons, Ltd.

High-density hydrogen storage in the form of renewable carbohydrate becomes possible because cell-free synthetic enzymatic pathway biotransformation (SyPaB) can 100% selectively convert carbohydrate and water to high-purity hydrogen and carbon dioxide under modest reaction conditions (below water boiling temperature and atmospheric pressure). Gravimetric density of carbohydrate (polysaccharide) is 14.8% H₂ mass, where water can be recycled from polymer electrolyte membrane fuel cells or 8.33% H₂ mass based on the water/carbohydrate slurry; volumetric density of carbohydrate is >100 kg of H₂/m³. Renewable carbohydrate would be more advantageous over methanol according to numerous criteria: substrate cost based on energy content (cost per gigajoule), energy conversion efficiency, catalyst cost and availability, sustainability, safety, toxicity, and applications. Huge potential markets of SyPaB from high-end applications (e.g., biohydrogenation for synthesis of chiral compounds and sugar batteries) to low-end applications (e.g., local satellite hydrogen generation stations, distributed electricity generators, and sugar fuel cell vehicles) would be motivation to solve the remaining obstacles soon. Copyright © 2012 John Wiley & Sons, Ltd.