Performance analysis of the phase-change heat-storage tank based on numerical simulation

Phase-change heat storage system contributes to the smooth operations of building energy supply and demand. In this paper, the numerical model of the heat-storage tank with phase change material blocks is established. The charge and discharge process of the heat-storage tank is analyzed with the numerical model. The performances of the heat-storage tank with and without phase change material blocks are compared by experiment and numerical simulation. The effects of structural parameters of phase change material blocks on the heat storage and release rate are comprehensively discussed, including the number and size of phase change material blocks. The results indicate that under the experimental conditions, the charge capacity and duration of the tank with phase change material blocks are extended by 7.43% and 8.3% respectively under the condition of replacing 6.75% volume of hot water with phase change material. The thermal stratification phenomenon in the heat-storage tank without phase change material blocks is more obvious. For certain volume of the phase change material, the performance analysis of three cases with different amount and size of phase change material blocks is investigated. The results show that the phase change material blocks with number and size of 24 and 0.45 m x 0.1 m x 0.1 m reduces the charge and discharge duration by 2.47% and 3.78% compared with those of 12 and 0.9 m x 0.1 m x 0.1 m.