Evaluation of thermal performance for bionic porous ceramic phase change material using micro-computed tomography and lattice Boltzmann method

Abstract

Recently, bionic bone porous aluminum nitride ceramics have been synthesized and corroborated to be skeleton for composite phase change materials (PCM), which possess the advantages of high thermal conductivity and excellent corrosion resistance. Due to the complexity of preparation and measurement of the samples, a reliable pore-scale simulation approach can well predict their effective thermal conductivity (ETC) and melting process. In this work, the real three-dimensional geometry structure is reconstructed by micro-computed tomography (CT) method, and a numerically generated Voronoi structure is adopted to mimic the porous structure for comparison. The effective thermal conductivity of the two structure models is calculated based on lattice Boltzmann method (LBM). The results show the numerically predicted ETC of two structures is consistent. Furthermore, the melting of molten salt PCM in the complex porous ceramic is simulated by 3D enthalpy-based LBM. The melting rate increased remarkably because of the connected heat transfer path. The thermal contact resistance between PCM and skeleton is considered by setting an interfacial layer. A larger thermal contact resistance leads to a smaller melting rate and weakens the enhancement effect of the porous skeleton. The numerical simulation based on CT scanning and LBM may reflect a better insight for the heat transfer mechanism and provide a quick analysis to design the optimal porous skeleton.