Effects of particle size reduction due to wear on heat transfer in a fluidized bed: A CFD-DEM study

Abstract

Particle wear behavior significantly affects combustion stability and operational costs. To reveal the underlying effects of particle size reduction on the heat transfer process, which are difficult to obtain experimentally, this study proposes a novel particle wear model. The model is experimentally calibrated and subsequently incorporated into a heat-fluid CFD-DEM platform. This is the first study to numerically investigate the impact of particle size reduction due to wear on the heat transfer characteristics in a fluidized bed. This study investigates the fluid dynamic and thermal behavior of particles after wear. It provides information on the system's macroscopic gas-solid flow regime (characterized by particle size and temperature distribution), the time-varying rules of particle wear and fragmentation rate, bed particle size distribution, and the relationship between single-particle diameter and temperature under different wear mechanisms. The primary innovation of this work lies in assessing the impact of different wear mechanisms on the key parameters (heating rate and temperature uniformity) during the heating process. Based on these findings, practical guidance is provided for optimizing industrial processes (adjusting particle flow patterns, optimizing debris distribution, and enhancing temperature monitoring at the bed bottom). The results reveal that different wear mechanisms lead to distinct distribution characteristics of particles within the bed. The abrasion mechanism enhances the heat transfer process, resulting in an approximately 16 % increase in the heating rate coefficient (C) and a 6 % improvement in temperature uniformity. In contrast, the fragmentation mechanism weakens the heat transfer process, leading to an approximately 33 % decrease in C and a 21 % reduction in temperature uniformity.