基于Na_2HPO_4·12H_2O相变储能热管理的储热过程研究

Thermal management based on Na_2HPO_4·12H_2O phase change heat storage

文章研究了水合盐相变储能材料Na_2HPO_4·12H_2O在发热器件热管理上的应用。在储热块的封装中,为了解决水合盐导热性能差的问题,将Na_2HPO_4·12H_2O填充在泡沫金属中以增强其换热;并采用不同厚度的铜片均热板对发热源的均热效果进行测试。通过测试在不同加热功率下均热板中心与边缘位置的温度,发现其温差随均热板厚度增大而减小。在6 W功率加热下,若使均热板温差不超过4℃,则均热板厚度应不小于0.5 mm;设定陶瓷片热点温度不超过70℃时,30 mm×30 mm×7 mm的储热块可以维持大概10 min。在非稳态储热过程的模拟中,由于Na_2HPO_4·12H_2O具有两个明显的相变区间,传统的考虑单相变点的模拟方法无法给出准确的温度响应,因此采用等效热容法考虑两个相变点进行了数值模拟,结果表明,低功率加热时,采用两个相变点的方法精度更高;而在高功率时,两种方法区别不大。

Salt hydrate based thermal energy storage material,Na2HPO4·12H2O,was studied for thermal management of electronics.Such a material usually has a poor thermal conductivity and hence was filled in a metal foam to enhance the thermal conductivity.Copper sheets with varying thickness were used to study the heat spreading effects on the heating module.With different levels of heating power,the temperature difference between the middle and the edge of the copper spreader was monitored.The results showed that an increase in the thickness of the copper sheet decreases the temperature difference.With 6W heating power,a 0.5 mm thick copper sheet should be used if the required temperature difference is less than 4℃.A heat storage module with a dimension of 30 mm×30 mm×7 mm could work for 10 minutes without overheating above 70℃.Simulations were performed with both one-melting-point model and two-melting-point model.The results showed that the two-melting point model worked better than the one-melting-point model at a low power,whereas little difference between the two models were seen at high powers.