Particle – Resolved Simulation of Anisothermal Fluidized Beds

Fluidized beds are used as a new heat transfer fluid in solar tower power plants.To optimize heat transfer in solar receivers, it is essential to characterize the heat exchange between the walls and the particles.Particle -Resolved Direct Numerical Simulation (PR-DNS) is thus used to study hydrodynamic interactions and heat flux in an anisothermal fluidsolid particles assembly.An original method was developed to compute hydrodynamic forces and thermal flux over the surface of the solid particle.In PR-DNS, velocity gradients and pressure are fully resolved in the vicinity of the interfaces between the fluid and the particles.However, PR-DNS requires several dozen of meshes in the particle's diameter and is therefore not suitable for the simulation of fluidized beds.To overcome this issue, Particle-Resolved Subgrid Corrected Simulation (PR-SCS) is introduced.In this framework, a coarse mesh is employed, and the partially captured velocity gradients and pressure are corrected by means of a mesh-dependent numerical correction.The method is validated for a single particle settling in an infinite medium, and then adapted to fluidized beds.The same methodology is developed for anisothermal flows.The heat flux received by the particle is computed over its surface.The numerical error due to mesh coarseness is corrected with a mesh-dependent correction.Finally, the collective effects of particles are examined in an anisothermal fluidized bed.