Tomography-based investigation of flow and heat transfer inside reticulated porous ceramics

Abstract

This study investigates the flow and heat transfer within reticulated porous ceramics, with the aim of enhancing the understanding of phenomena occurring at the pore scale in order to extract useful information for the optimisation of heat sinks or other reticulated porous devices in engineering applications. In this study, X-ray computed tomography is used to reconstruct the reticulated porous ceramic. From the voxel mesh, the real geometry of the foam sample can be obtained, and an unstructured mesh is generated using ICEM. Then, a fully coupled heat transfer model is established. Based on this model, the transient conjugate heat transfer between the airstream and the porous matrix is solved using FLUENT software. The numerical results show that the pressure drop vs. the superficial velocity follows the Darcy–Forchheimer equation, and the border-affected region is only 1–2 times the mean cell size. Moreover, a local thermal equilibrium lasting for 7–10 s is found in the transient coupled flow and heat transfer process in this study. Additionally, the local convective heat transfer coefficient, which mainly depends on the velocity, is constant along the flow direction, and the instantaneous volumetric heat transfer coefficient increases monotonically with time. The obtained results are important theoretical supplements for understanding the flow and heat transfer in porous materials, and are crucial for enhancing the heat transfer in applications of reticulated porous ceramic materials.