Multiscale analysis of particle flow characteristics in buried tube waste heat recovery heat exchanger

This work proposed a self-designed buried tube heat recovery exchanger, employing a multiscale analysis to examine how particle size and friction coefficient influence flow behavior between the tubes. The results show that: Macroscopically, increasing particle size reduces dead zone coverage, central flow particle fraction, and residence time. Conversely, the particle friction coefficient has an opposing effect. As the friction coefficient rises from 0.45 to 0.80, the dead zone's coverage range widens from +/- 30 degrees to +/- 40 degrees, increasing flow resistance. Microscopically, particle size expansion from 0.1 mm to 1.5 mm alters force chain distribution from -20 degrees to 60 degrees horizontally to 20 degrees to 70 degrees, with a reduction in horizontal arch force chains. An increase in friction coefficient promotes horizontal development of force chains, increasing horizontal arch force chains. Microscopically, particle size barely affects the probability density of F/F<overline>, but a higher friction coefficient raises the likelihood of F/F<overline>>1, increasing an arch tendency.