Experimental and simulated optimization study on dynamic heat discharge performance of multi-units water tank with PCM

The water tank is most commonly a crucial energy storage device of a solar heating system. However, few existing studies have focused on the quantitative analysis of the heat discharge process of a square water tank. In this paper, a multi-units water tank with phase change material (MWT-PCM) was proposed. The dynamic heat discharge performances of the MWT-PCM and the conventional water tank both with 235.8 dm 3 were compared experimentally. A validated mathematical model was established to optimize the configuration of the MWT-PCM. Results demonstrated that: (1) The water temperature of both tanks had a sharp decline at the initial stage of the heat discharge process. (2) The instantaneous residual effective heat and the instantaneous heat supply of the WMT-PCM were 127% and 45.6% higher than that of the conventional water tank on average, respectively. (3) Due to the PCM, the effective heat discharge time could be prolonged by about 90 min. (4) When the PCM was arranged in a multi-unit manner, a small flow rate operation was recommended. However, the effect of changes in the total mass of the PCM was not obvious, and thus, for the given total mass, a smaller pipe diameter was recommended.