泡沫金属复合相变材料的凝固及接触间距影响

Effect of Contact Gap and Solidification for Metal Foam Composite Phase Change Materials

相变材料(phase change material,PCM)具有解决能源利用时空不匹配问题的潜力,将PCM与泡沫金属进行复合是强化其传热性能的有效措施之一。本文针对一类泡沫金属复合PCM的凝固过程进行了三维数值模拟研究,分析了泡沫金属与恒壁温面不同接触间距对复合PCM凝固过程的影响规律。研究发现,复合PCM由于其泡沫金属框架导热系数较高,且增大了PCM的传热面积,可提高复合PCM的传热性能,并使复合PCM内部温度分布更为均匀;在其凝固过程的中后期,局部范围内泡沫金属与PCM传热现象显著。针对本文所研究的复合PCM,泡沫金属与恒壁温面之间的接触间距可影响其传热过程,其凝固速度也随两者间距的增加而减慢,呈非线性变化。同时,在该复合PCM底部凝固的传热过程中,自然对流换热不占主导地位。

The phase change material(PCM)has the potential to solve the mismatch problem of time and space in energy utilization.The composite of PCM and metal foam is an effective scheme to enhance its heat transfer performance.In this paper,the solidification process of composite PCM was investigated based on numerical simulation.The effect of various contact gap between the metal foam and the constant temperature wall was also studied.Due to the higher thermal conductivity of the metal foam frame and the increase of the heat transfer area for PCM,the heat transfer performance of the composite PCM can be improved,and the internal temperature distribution is more uniform.In the middle and late stages of solidification process,the heat transfer between metal foam and PCM is obvious in local area.For the composite PCM studied in this paper,the contact gap affect the overall heat transfer process,and the solidification velocity decreases with the increase of the gap and the trend is nonlinear.Meanwhile,natural convection is not the main factor of solidification from the bottom of the composite PCM.