Comminution process is widely used in industry to produce fine particles. We developed a mathematical model of comminution in order to analyze particle size reduction in an impact pulverizer. In our model, it is assumed that parameter a, which represents particle breakage modes, depends on both impact velocity and size of the particles. To obtain that dependence, particle-size distribution was measured experimentally before and after the breakage using a jet-mill. We implemented the mathematical model into the simulation based on computational fluid dynamics (CFD) and discrete phase model (DPM). It was confirmed that the simulation results coincide with the experimental ones in a rotary mill. Therefore, we conclude that it is important to consider the dependence of impact velocity as well as particle size on the breakage modes.

In this study, porous structured three-way catalyst particles were synthesized through a spray pyrolysis followed by heating processes using template particles. When nitrogen was used as the carrier gas, porous catalyst particles were synthesized while maintaining the pore structure of the particles. In addition, the internal structure of the synthesized porous catalyst particles was analyzed by using TEM Tomography, and the interconnected pore structures were confirmed inside the particles. Furthermore, the CO₂ adsorption rate results show that the introduction of porous structure contributes to the improvement of mass transfer coefficient.

Langevin dynamics (LD) method is a modelling technique using pseudo-random numbers to reproduce the acceleration of aerosol particles due to random collisions of gas molecules onto the particles. Although the LD method can reproduce the Brownian motion of particles and motion due to inertial force and/or external force, it is difficult to understand the behavior of aerosol, which is group of particles, from the information on the motion of individual particles. In this study, a novel calculation method was developed to obtain the concentration distribution of aerosol by accumulating the information of position of particles calculated by the LD method, and it was applied to the diffusion of aerosol flowing steadily in a cylindrical tube. The concentration distribution obtained by this method agreed well with that obtained by solving the conventional convective-diffusion equation. Furthermore, change in cup-mixing concentration of aerosol in axial direction calculated from the concentration distribution agreed well also with the penetration expressed by Gormley & Kennedy.

This paper describes the configuration and performance of the developed duct for evaluation tests and examples of evaluation measurements. In addition, the equivalence with the gravimetric measurement that cannot be accurately evaluated for the electrostatic detection type dust meter, which was a pending issue when the JIS standard was established, is discussed. As a result, the charging of dust in the test duct was confirmed and was assumed to be caused by triboelectrification with obstacles such as agitator plates and rectifying wire mesh. And since an exponentially decreasing relationship appeared between the dust concentration in the duct and the dust charge, this change in dust charge disrupted the linear relationship between the dust meter readings and the gravimetric measurements, making evaluation difficult. This indicates that when conducting equivalency tests using test ducts, dust charging should be fully considered, and in some cases, dust charge should be measured and appropriately corrected.