相变储热材料三水醋酸钠循环热稳定性实验与数值模拟研究

Experimental Study and Numerical Simulation on Thermal Circulation Stability of CH3COONa·3H2O as Phase Change Material

三水醋酸钠(CH3COONa·3H2O)是一种常见的相变材料。选择Na2HPO4·12H2O作为成核剂,羧甲基纤维素钠(CMC)作为增稠剂,利用步冷曲线法和差示扫描量热法研究CH 3COONa·3H2O相变材料的循环融冻热稳定性;利用FLUENT软件,对CH 3COONa·3H2O在试管中熔化凝固过程进行数值模拟。结果表明,CH3COONa·3H2O相变过程的数值模拟结果与不同实验条件下相变材料熔化凝固过程所需时间能够较好地匹配,说明基于FLUENT软件的相变材料数值模拟方法可以为实际实验提供参考;含有添加剂的CH 3COONa·3H2O相变材料在循环融冻100次过程中,相变温度稳定在55℃左右,过冷度在1~4℃之间变化,且增稠剂与成核剂有较好的循环融冻热稳定性,利用T-history法估算相变材料的相变潜热值减少15.1%左右。

Sodium acetate trihydrate(CH 3COONa·3H2O)is a kind of common phase change materials.The numerical simulation on melting-freezing process of CH 3COONa·3H2O was studied based on the FLUENT software;the CH 3COONa·3H2O composite phase change material was prepared by adding Na 2HPO 4·12H2O as the nucleating agent and carboxymethyl cellulose(CMC)as the thickening agent.The thermal circulation stability of the CH 3COONa·3H2O composite phase change material was studied by the cooling curve method and the differential scanning calorimetry(DSC)test.Experimental results show that the numerical simulation can successfully estimate the time spending on a melting-freezing process of CH 3COONa·3H2O,which provides reference to actual test in the lab;after 100 melting-freezing cycles,the phase change temperature of the composite material nearly stabilized at 55℃,and the degree of supercooling ranged from 1℃to 4℃;the nucleating and thickening agent have good themal stability;by using the T-history method,the latent heat is reduced by 15.1%.