| 摘要: |
| 相变蓄热技术是提高太阳能利用效率的重要途径之一。本文基于三水合醋酸钠，搭建了一套相变蓄热水箱实验系统，在初始水温为80 ℃、进水温度为5 ℃的工况下，测试得到了水箱的热力学特性，并基于水箱内各温度点随无量纲时间的变化，采用填充效率和混合数分析法，分析了相变蓄热水箱的热分层特性。实验结果表明：当水箱温度为80 ℃时，普通水箱和相变蓄热水箱的能量分别为18.81 MJ和19.34 MJ。进口流量相同时，相变蓄热球越靠近水箱进口，水箱的热分层效果越好。普通水箱的热分层效果要强于相变蓄热球在第1、2和3层时，但弱于相变蓄热球在第4层。当进口流量为9 L/min、t*=1时，相变蓄热球在第1层和第4层时的填充效率分别为0.497和0.581，而普通水箱的填充效率为0.573。随着进水流量的增大，水箱内混合程度升高，斜温层厚度变大，水箱分层效果下降。当进口流量大于7 L/min且相变蓄热球位于底部时，相变蓄热水箱的热分层特性最佳。 |
| 关键词: 储热水箱 相变材料 填充效率 热分层 |
| DOI： |
| 投稿时间：2019-04-13 修订日期：2019-06-19
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| 基金项目:国家自然科学基金（51606126）资助项目。 |
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| Experimental Study on the Effect of Phase Change Thermal Storage Ball on Thermal Stratification of Water Tank |
| Zhang Qiaodan,Zhang Hua,Wang Zilong,Chen Yankang,Huang Huajie,Liu Zhanjie |
| (School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering;Qingdao Haier-Medical Co., Ltd.) |
| Abstract: |
| Thermal storage technology with phase change material (PCM) is one of the important ways to improve the utilization efficiency of solar energy. A hot water tank experimental system with sodium acetate trihydrate ball as PCM was built. The thermodynamic characteristics based on the temperature in the water tank were tested under an initial water temperature of 80 ℃ and inlet water temperature of 5 ℃. According to the change of water temperature in the tank with the dimensionless time, a filling efficiency analysis method was used to analyze the thermal stratification characteristics of the hot water tank with PCM. This analysis includes the curve of temperature change and filling efficiency when the water flow rates were 1, 3, 5, 7, and 9 L/min, respectively. The experimental results show that when the water tank temperature is 80 ℃, the energy of the ordinary water tank and the hot water tank with PCM are 18.81 MJ and 19.34 MJ respectively. When the water flow rate is the same, the closer the ball with PCM is to the water tank inlet, the better the heat stratification effect of the water tank is. The thermal stratification effect of the ordinary water tank is stronger than that of water tank with PCM when the ball is at the first, second, and third layers, but weaker than that of water tank with PCM when the ball is at the fourth layer. When the inlet flow rate is 9 L/min, the filling efficiency of water tank with PCM is 0.497 and 0.581 when the ball is in the first layer and the fourth layer, respectively, and the filling efficiency of the ordinary water tank is 0.573, when t*=1. As the water flow rate increases, the mixing degree of the hot and cold water increases, and the thickness of the thermocline layer in the water tank increases, which decreases the stratification effect. When the inlet flow rate is greater than 7 L/min and the PCM ball is at the bottom, the thermal stratification characteristics of the hot water tank with PCM are optimal. |
| Key words: hot storage tank phase change material filling efficiency thermal stratification |
