Impacts of solid stress model on MP-PIC simulation of a CFB riser with EMMS drag

Abstract

The cluster-based EMMS (energy minimization multi-scale) drag model in combination with MP-PIC (multi-phase particle in cell) method can successfully simulate the fluidization behavior in CFBs (circulating fluidized beds). The solid normal stress model is very important to MP-PIC simulations, but still lacks thoroughly investigation, especially in CFB riser simulation. In this work, the effects of parameters from the solid normal stress model have been investigated by using 2D simulations of a laboratory-scale CFB riser with MFIX (Multiphase Flow with Interphase eXchanges) open-source code. The results show that the role of the solid stress parameters is more significant when the solid approaches close packing state. Based on the comparison between simulation results and experimental data and the elapsed simulation time, optimal values for the solid stress model parameters were obtained. The thickness of the third direction for 2D simulations has also been investigated. Increase of the thickness entails additional computational costs with little effect on the accuracy and the recommended value of thickness is the diameter of one single particle.