相变蓄热水箱分层特性的实验研究

Experimental Study on Stratification Characteristics of the Phase Change of a Hot Water Tank

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,并采用填充效率分析法以及火用效率分析法,在进水体积流量分别为1、3、5、7、9 L/min时,分析了相变蓄热水箱的热分层特性。结果表明,当水箱温度为80℃时,普通水箱、相变蓄热球PCM48水箱、相变蓄热球PCM58水箱的热能分别为18. 81、19. 34、19. 07 MJ。进口体积流量相同时,相变蓄热球越靠近水箱进口,水箱的热分层效果越好。随着进水体积流量的增大,分层效果下降。不同水箱的理查森数Ri在t^*=0. 5达到最大值,Ri随相变蓄热球位置的降低而减小,PCM48和PCM58在第4层时的Ri分别为7. 569和7. 781,而在第1层时的Ri分别减小为7. 03和7. 145,表明水箱热分层的程度随着相变蓄热球位置的升高而降低。

A hot water tank tast bench with phase change material(PCM) of sodium acetate trihydrate was built. The thermodynamic characteristics of the hot water tank with PCM were tested under the conditions of an initial water temperature of 80 ℃ and an inlet water temperature of 5 ℃ . The analytical method and the enthalpy efficiency analysis method were used to analyze the thermal stratification characteristics of the hot water storage tank with PCM when the influent flow rates were 1 L/min,3 L/min,5 L/min,7 L/min,and 9 L/min,respectively. The experimental results show that when the water tank temperature was 80 ℃,the energy of the ordinary water tanks,the tanks with prase change heat storage ball of PCM48 and PCM58,were 18. 81 MJ,19. 34 MJ,and 19. 07 MJ,respectively. When the inlet flow rate was the same,the closer the heat storage ball with PCM is to the water tank inlet,the better the heat stratification effect of the water tank. As the influent flow rate increased,the stratification effect decreased. The number of Ri in different water tanks reached a maximum at t^*= 0. 5;the Richardson number(Ri) decreased with the lower position of the heat storage ball with PCM. The Ri of the PCM48 and PCM58 in the fourth layer were 7. 569 and 7. 78,respectively. The Ri at the layer were reduced to 7. 03 and 7. 145,respectively,indicating that the degree of thermal stratification of the tank decreased with the higher position of the heat storage ball with PCM.