Effect of particle shape on particle flow and heat transfer behavior based on computational fluid dynamics-discrete element modeling

Particle fluidization technology is often involved in biomass industrial applications. However, the utilization of biomass particles requires gas-solid flow and processes, such as heat transfer and reaction transformation. Therefore, in this paper, biomass pellets were processed into cylindrical particles and designed with five aspect ratios (AR = 0.5, 1.0, 1.5, 2.0, and 3.0). The kinetic and heat transfer characteristics of cylindrical particles with different aspect ratios in a bubbling fluidized bed were analyzed from macroscopic and microscopic perspectives using the Computational Fluid Dynamics-Discrete Element Method. The simulation results show that the higher the sphericity of cylindrical particles (AR = 1), there is obvious particle aggregation near the wall, and the higher the bed height, the more asymmetric the particle flux distribution. Increasing the gas superficial velocity helps to improve the mixing quality of the particles, convective heat transfer, particle temperature cooling rate, and uniformity of particle temperature distribution. The contact force between particles is much larger than the gas-particle interaction force, and the particle contact force is mainly concentrated on both sides of the wall. The larger the aspect ratio of cylindrical particles, the smaller and more uniformly distributed the particle contact force at the wall. Furthermore, when AR > 1, the drag force and lift force gradually increase with the increase in particle aspect ratio, the faster the particle temperature decreases, the larger the particle convective heat transfer, and the larger the standard deviation of temperature.