Three-dimensional numerical simulation of solid-liquid phase change in the cavity of composite structures based on TPMS

Solid skeletons will play an important role in improving the thermal properties of phase change materials. For this reason, the efforts should be dedicated to studying the heat transfer characteristics of solid-liquid phase change with different structural skeletons. In this paper, the composite structures spliced with Gyroid and Diamond skeletons in the horizontal or vertical directions were established by using the Triply Periodic Minimal Surface method. A three-dimensional dimensionless lattice Boltzmann model of the phase change material (PCM) cavity with the spliced skeleton was developed by using the two-region model for solid-liquid phase change in the mushy zone. Based on the pore scale, the phase change heat transfer characteristics under the thermal conductivity ratio of the skeleton to PCM of 100 were analyzed in depth with constant temperature heating at the left wall surface. The results showed that the skeleton spliced in different directions has different effects on the temperature field and heat transfer characteristics of the phase change process. The (G + D)H spliced skeleton which was arranged by Gyroid and Diamond skeletons in the horizontal direction led to a faster melting rate of the PCM than the (D + G)H spliced skeleton which was arranged by Diamond and Gyroid skeletons. The promotion effect of a large porosity skeleton on the melting process of PCM was less than that of a small porosity skeleton. The dimensionless complete melting time for the cavity containing skeleton with porosity epsilon = 0.915 was increased by 35.7 % and 19.4 % compared to the cavities containing skeletons with porosity epsilon = 0.826 and 0.871, respectively. This study lays the foundation for the development and application of TPMS spliced skeletons in phase change heat storage and enhanced heat transfer technologies.