Dust explosion process is rapid and complex due to the multiphase flow, the fast physical and chemical conversions, and the high temperature. Models of dust explosion are limited and simplified in the simulation, which may overpredict the explosion characteristics. To better understand the processes, a single-particle model is introduced with the porosity of the particle to investigate the influence of pore expansion inside of the particle during dust expansion. This model includes a new devolatilization model based on the kinetics of coal pyrolysis gas which is derived based on the data obtained by TGA-FTIR experiments. With this detailed model, the physical and chemical processes were analyzed, and simplifications were introduced to improve numerical efficiency. Then dust explosion studies were carried out in MIKE 3 apparatus and aided with the computational fluid dynamics modeling. The effect of particle size is explored with experimental and simulation methods. The particle size influences the dispersion and combustion process. In the dispersion process, the larger particles tend to accumulate at the lower position of the explosion tube. This will further influence the explosion characters as the concentration are not constant when the particle size changes. In addition, the concentration distribution leads to a faster flame speed compared to a uniform dust cloud distribution. More studies on the pneumatic system, the turbulence level, the particle velocity, and particle decomposition behavior are also included.