Particle & Particle Systems Characterization

In this paper results generated from microscopic image analysis were compared with data obtained by dynamic (automated) image analysis in terms of crystal size and shape. Comparisons were made of processing time, number of crystals and accuracy. It was found that e.g. D₅₀ by the two techniques were comparable whereas substantial differences in span of the distribution and aspect ratio were obtained.

For this study, a 4 stage electrical low pressure impactor was designed to measure the real-time size distribution of diesel particulate matter (DPM). A performance evaluation with test material (sodium chloride and dioctyl sebacate) was performed showing good agreement with scanning mobility particle sizer (SMPS) results. Then, measurements of DPM with a real Diesel engine were performed and the size distribution could be obtained within 5 seconds. Furthermore, the effective density of the DPM could be obtained using the calculated results and the SMPS data.

The traditional use of the laser diffraction technique provides only line-of-sight liquid spray drop-size distribution. However, deconvolution of the measurements can be performed for axisymmetric sprays in order to determine local spray characteristics. Using the maximum entropy principle local extinction coefficient values are determined. The coherence of the overall approach is discussed in detail and solutions for improving the spatial resolution are presented. Finally, local volume-weighted, drop-size distributions are derived.

We inject a large number of newly created nano-particle aggregates into a chamber for the purpose of removing harmful contents in an indoor environment. An Euler-type particulate-phase-transport model is developed and validated by comparing with experimental data. The study shows that the transient behavior of particle distributions is determined by many factors, including particle size, particle settling speed, sampling location, and velocity distribution.

Issues relevant to the design of reacting and nonreacting fluid-solid contacting devices using narrowly sized cylindrical particles, e.g., pressure drop behavior, fluidization behavior and settling behavior, both in Stokes law as well as the intermediate region, are investigated. It is shown, that converting the equivalent diameter by the sphericity shape factor might be critical. Improved predictions are presented whose parameters were optimized using a database of nonspherical particles.

This paper presents valid data on mechanical properties of grain, forage cereals and different types of flour which are necessary in order to do a safe silo design. The present work i) provides the relevant values needed when designing silos (e.g., the Poisson ratio, the dilatancy angle and the modulus of elasticity, etc.), and ii) investigates the suitability of standard tests for these materials (e.g., the direct shear, the oedometric and triaxial test).