A numerical and experimental comparison of heat transfer in a quasi two-dimensional packed bed

Heat transfer plays a major role in many industrial processes taking place in packed beds. An accurate and reliable simulation of the heat exchange between particles is therefore crucial for a reliable operation and to optimize the processes in the bed. The discrete ordinates method (DOM) provides an established numerical technique to model radiative heat transfer in granular media that offers the possibility to consider the directional dependence of the radiation propagation. In this work, DOM is compared with Monte Carlo ray tracing, which provides an alternative method for heat transfer simulations. Geomet-rically simple configurations are used to investigate the influence of the angular discretization on the accuracy of the results and the computation time in both methods. The obtained insights are then transferred to a more complex configuration of a quasi two-dimensional test rig consisting of metal rods for which also experimental results are available. Our results show that both DOM and Monte Carlo ray tracing allow for an accurate simulation of heat transfer in packed beds. Monte Carlo ray tracing requires thereby computation times that are surprisingly competitive (although still somewhat slower) compared to DOM and allows for an easier computation of highly accurate reference solutions. In our preliminary comparison to the experimental test rig, Monte Carlo ray tracing also provides the advantage that it can more easily model highly specular materials such as stainless steel. Both methods are comparable for diffuse materials such as magnesium oxide.(c) 2023 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Automated summary

Heat transfer is crucial in industrial processes in packed beds. The discrete ordinates method (DOM) and Monte Carlo ray tracing are compared for heat transfer simulations. Both methods show accurate results, with Monte Carlo ray tracing offering the advantage of easier computation for highly specular materials.