金属泡沫中填充石蜡的相变换热特性实验研究

Experimental Study on the Heat Transfer of Metal Foam Filled in Paraffin

本文对金属铜泡沫填充石蜡的相变换热特征进行了实验研究,通过测试试件加热面及内部的温度响应曲线,分析了金属泡沫填充及自然对流对石蜡非稳态相变换热过程的影响。研究结果表明,采用顶部加热方式时,石蜡内部的换热以纯导热为主,而采用底部加热时,液态石蜡内的自然对流作用使相界面移动速度更快,试件内部温度一致性更好,同时在相变对流区可实现对加热面的温度控制。金属泡沫的填充可强化石蜡内的导热但抑制液态石蜡的自然对流,前者使得试件加热面温升减缓,相界面移动加快,后者则导致底部加热时石蜡的相变区分为相变导热区和相变对流区。金属泡沫的导热强化能力在试件换热中占据主导作用。

In this study,the thermal performance of paraffin saturated open cell metal foam was experimentally investigated by tracking the heated surface and internal temperatures.The effects of metal foam and natural convection on heat transfer in paraffin were discussed.The results showed that the heat conduction played a dominant role for the case of top heating.For the case of bottom heating,the natural convection in liquid paraffin led to the quicker phase change interface movement and more uniform internal temperature.Meanwhile,the temperature of heated surface was controlled in a small range in the phase change-convection zone.The inclusion of metal foam greatly improved the thermal conductivity of paraffin but suppressed the liquid nature convection.The former resulted in the slower temperature rising of heated surface and quicker phase change interface movement.The latter led that the phase change zone can be divided into the phase change-conduction zone and phase change-convection zone for the bottom heating.The enhanced heat conduction due to the fill of metal foam played a dominant role in the heat transfer of paraffin.