Low temperature fuel cells
Fundamentals and Survey of Systems
Heat transfer in fuel cells
Published Online: 15 DEC 2010
Copyright © John Wiley & Sons, Ltd. All rights reserved.
Handbook of Fuel Cells
How to Cite
Divisek, J. 2010. Low temperature fuel cells. Handbook of Fuel Cells. .
- Published Online: 15 DEC 2010
The principle of energy conservation determines the energy balance equation, which can be generally formulated as the sum of single rates of energy input and output, energy production and accumulation. In a fuel cell, the balance takes into account the thermal and the electrical energy. There are three modes of heat transfer process occurring in a fuel cell: conduction, convection and radiation. The fundamentals of these processes are discussed together with the heat transfer occurring with the change of state, such as evaporation, condensation and additional chemical reactions.
The general energy balance equation is analyzed with respect to the heat sources, energy balances for single phases, boundary conditions and parameter definition. An approach for the delocalization of reaction entropy in fuel cells is also given.
Based on the general heat transfer equations, water and heat management for low temperature fuel cells (hydrogen and direct methanol) is discussed considering cell structure, current density and temperature distribution.
Heat transfer in high temperature fuel cells (HTFCs) is extremely important for the system evaluation. Heat management for high temperature fuel cells (molten carbonate fuel cells (MCFCs) and solid oxide fuel cells (SOFCs)) is analyzed. Heat generation in HTFCs is strongly influenced by chemical reactions, such as methane/water reforming. Thermodynamic analysis and reaction kinetics of the reforming reaction are presented. A performance analysis of MCFCs and planar and tubular SOFCs is made considering the cell geometry, current density and temperature distribution. Finally, heat removal for cogeneration in SOFCs is dealt with.
- drag coefficient;
- fluid temperature;
- fluid velocity;
- heat capacity;
- heat transfer;
- heat transfer coefficient;
- enthalpy of vaporization;
- solid temperature;
- thermal conductivity;
- thermal diffusivity