Chemical Engineering Journal, Vol.361, 1543-1556, 2019
CFD simulation and experimental validation of tortuosity effects on pellet-fluid heat transfer of regularly stacked multi-lobe particles
This paper investigated the steady-state heat transfer of multi-lobe particles in a packed bed both numerically and experimentally. In the numerical analysis, continuity, motion, and energy equations were solved and heat transfer coefficient was calculated. In the experimental work, two different arrangements of structured beds with a tube to particle diameter ratio (N) ranging from 2 to 3 were examined. Finite element method (FEM) was used to solve partial equations using the FEMLAB2.3 software. The results indicated that the two beds with the same porosity had different particle-to-fluid Nusselt numbers which could be caused by tortuosity differences. Moreover, the comparison of local Nusselt number with previous empirical correlations revealed that neglecting tortuosity caused correlations to be unable to predict the experimental Nusselt number. Therefore, tortuosity number was calculated from a numerical method and a modified correlation was proposed according to the CFD results, which reduced the average error from 12.37% to 2.97% by considering the tortuosity effect.