Gas-solid heat transfer in assemblies of cubes for ReV ≤ 100

Abstract

The thermal lattice Boltzmann method using an immersed moving boundary condition was employed to calculate the particle-to-fluid heat transfer in an assembly of super-quadric cubes. The simulations were performed for Reynolds numbers 1–100 (based on the volume equivalent diameter) and solid volume fractions ϕ = 0.1–0.45. The simulation results show that the Nusselt numbers for assemblies of super-quadric cubes are larger than those for assemblies of spheres, in particular for high solid volume fractions. A relationship between the average Nusselt number and the drag force (Chen & Müller, 2018) for assemblies of cubes was developed. It was found that the average drag force acting on cubes increases faster with increasing solid volume fraction than the average Nusselt number. Defining the Reynolds number and the Nusselt number using the hydraulic diameter of the packing system (Reh) and the Sauter diameter of the cube, respectively, the Nusselt number correlation of Chen & Müller (2019), that was proposed for assemblies of spheres, can be applied for assemblies of non-spherical particles. We also demonstrate that the proposed Nusselt number correlation predicts well the heat transfer between a gas and ellipsoidal or cylindrical particles.