肋片和多孔介质强化梯级相变储热系统性能的对比研究

Aiming at the problem of low heat transfer rate caused by the poor thermal conductivity of the phase change material, 3-D numerical simulation is used to study the enhancement effect of fins and porous media on the discharging performance of the cascaded latent heat storage system. Gradient porosity is proposed to further improve the discharging performance of the system, and different enhancement methods are analyzed and compared from the two aspects of the discharging rate and efficiency. The results show that adding fins has a more significant effect on heat transfer enhancement in the sensible heat discharging process, while adding porous media is more significant in the latent heat discharging process. Adding only porous media during the whole discharging process shows better thermal performance than adding only fins. When adding fins and porous media at the same time, the discharging performance of the system is the best, and the complete solidification time of PCMs is reduced by 40%. There is no significant difference in the discharging efficiency of the system under the three porosity gradient conditions, but in the case of negative gradient porosity, the discharging rate is higher and more uniform. Compared with the case of positive gradient porosity, negative gradient porosity has better thermal performance.