Effects of particle surface roughness on heat transfer properties of particles flowing around the heat exchanger tube

Abstract

High-temperature solid particles contain relatively rich waste heat resources, and the moving bed heat exchanger has a significant advantage in the direct contact of particles to extract heat. Considering the varying surface roughness of the actual particles, the effect of particle surface roughness on heat exchange in heat exchanger tubes should not be neglected. To this end, a coupled CFD-DEM computational model of high-temperature solid particles flowing around a single heat exchanger tube is established, and the effect of particle surface roughness on heat transfer from a single heat exchanger tube is analyzed. The results show that f_s (static friction coefficient between particles) has a more significant effect on the heat transfer performance than f_r (rolling friction coefficient between particles). The mean heat transfer coefficients of the heat exchanger tube decrease with increasing f_s. When the f_s increases from 0.05 to 0.3, the mean heat transfer coefficients of the single tube decreases from 239.99 W/(m²∙K) to 234.59 W/(m²∙K), with a decrease of 2.25%. The f_r has little effect on the heat transfer of high temperature solid particles flowing around the heat exchanger tube.