The effect of phase change material balls on the thermal characteristics in hot water tanks: CFD research
The effect of phase change material balls on the thermal characteristics in hot water tanks: CFD research
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相变材料球对热水箱热特性的影响：CFD 研究
DOI：
10.1016/j.applthermaleng.2020.115557
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发表时间：
2020
影响因子：
6.4
通讯作者：
Wu Chunfei
中科院分区：
文献类型：
--
作者：
Qin Yanbin;Wang Zilong;Zhang Hua;Dou Binlin;Zhang Guanhua;Wu Weidong;Wu Chunfei
储热水箱是太阳能利用系统中的关键部件。相变材料可以显著提高热水箱的热效率和蓄热能力。本研究以低熔点金属、三水醋酸钠及石蜡为材料，建立热水箱之三维模型，并以实验结果加以验证。研究了入口流量、相变材料的导热系数和位置对热水箱热性能的影响。结果表明，采用低熔点金属材料制作的热水箱具有较高的导热系数，具有较好的使用性能。此外，在入口流量为9 L/min时，低熔点金属、三水醋酸钠和石蜡水箱的释放热能分别为17.22 MJ、16.77 MJ和16.37 MJ，其熔化率分别为0%、28%和47%。此外，当入口流速从5 L/min变化到9 L/min时，等温表面之间的距离（35 ℃和75 ℃）的低熔点金属、三水醋酸钠和石蜡水箱的厚度分别从3.98 cm增加到7.96 cm、5.49 cm增加到8.57 cm和5.82 cm增加到8.87 cm，因此，在相同的相变材料球入口流量和位置下，低熔点金属的热水箱的填充效率和Richardson数最高。因此，在热水箱中应用低熔点金属作为相变材料，不仅可以提高蓄热能力，而且可以增加热分层。
Hot water storage tank is the crucial element in solar energy utilization systems. Phase change material can significantly improve the thermal efficiency and the heat storage of hot water tank. In this study, a 3-D model for hot water tank with low melting point metals, sodium acetate trihydrate, and paraffin wax was established and validated by the experimental results. The influence of the inlet flow rates, the thermal conductivity and positions of the phase change materials on thermal characteristics of the hot water tank had been investigated. Results show that the hot water tank with low melting point metals has better performance due to its high thermal conductivity. Besides, with the inlet flow rate of 9 L/min, the released heat energy of the low melting point metals, the sodium acetate trihydrate and the paraffin wax water tanks are 17.22 MJ, 16.77 MJ and 16.37 MJ with the melting rates at the end time of 0%, 28% and 47%, respectively. In addition, as the inlet flow rate varies from 5 L/min to 9 L/min, the distances between the isothermal surfaces (35 °C and 75 °C) of the low melting point metals, the sodium acetate trihydrate and the paraffin wax water tanks increases from 3.98 cm to 7.96 cm, 5.49 cm to 8.57 cm and 5.82 cm to 8.87 cm, respectively, thus, the filling efficiency and Richardson number of the hot water tank with low melting point metals are the highest at the same inlet flow rate and position of the phase change material balls. Therefore, the application of low melting point metals as a phase change material in hot water tank not only can improve the heat storage capacity, but also increase thermal stratification.