Performance enhancement of thermal energy storage units for plant factories
To overcome the low thermal conductivity of PCM,a heat transfer enhancement approach involving metal foam combined with metal fins is introduced for tube-shell latent-energy storage units(LESUs).The metal foam is partially filled in the LESU to further accelerate the heat transfer process during energy storage.Various configurations of the metal foam are examined in this study.Based on the enthalpy-porosity method,the enhanced melting process of PCM using metal fins and foam in a LESU is numerically investigated.The dynamic melting process,temperature response,dimensionless heat storage capacity,and economical efficiency of the LESU with different configurations of metal foam are compared.The results show that metal foam is highly effective in enhancing the energy storage process in PCM systems as the melting time of PCM can be reduced by up to 85%.The filling position of the foam metal also plays a crucial role in the performance enhancement of this system.It is found that the optimal configuration of the metal foam is achieved by filling it between the tip of the fin,which is directed away from the heat transfer fluid,and the shell of the LESU.The thermal energy storage capacity per unit time in the LESU with an optimal metal-foam configuration 6.5-times that of an LESU without metal foam.Based on the optimal LESU,the variation of the liquid fraction of PCM under different heating temperatures are calculated and nondimensionalized.A fitting formula for predicting the melting process of PCM based on the Fourier number(Fo)and Stefan number(Ste)is proposed.This work furthers the development of solid-liquid phase-change thermal storage technology and provides guidance for the design of solar photovoltaic LESUs for application in plant factories.
plant factorythermal energy storagephase change materialperformance enhancement
万方数据
维普
