Development of view factor correlations for modeling thermal radiation in solid particle solar receivers using CFD-DEM

Radiation heat transfer must be modeled when designing any high temperature solid particle solar receiver or particle-fluid heat exchanger, but computationally efficient radiation models are not currently available in coupled Computational Fluid Dynamics - Discrete Element Method (CFD-DEM) codes, which is the focus of this work. Monte Carlo ray tracing simulations were run to find view factors between particles in packed beds, and correlations were found to estimate both particle-particle and particle-wall radiation view factors based on distance alone. The correlations can be readily implemented into any CFD-DEM code to model radiation heat transfer, which is demonstrated using the LIGGGHTS-OpenFOAM-CFDEM software combination. With the addition of the radiation models described, all relevant heat transfer modes in a dense particle flow can now accounted for, and LIGGGHTS-OpenFOAM-CFDEM can be used to model particle-based solar receivers and heat exchangers at high temperature