开孔金属泡沫有效热导率的理论分析与实验研究

Study on effective thermal conductivity of open metal foam

采用能量守恒定律和光学厚近似法,建立了开孔金属泡沫有效热导率的计算模型,分析了温度和压力等因素对传热的影响,并应用高温真空石墨加热炉对开孔金属泡沫的有效热导率进行了实验测量。理论值与测量值基本吻合,各个测量点的平均相对误差<5%,最大相对误差低于10%。结果表明,开孔泡沫金属的有效热导率随温度和压力的增加而增大,在低温情况下(T<100℃),开孔泡沫金属内部的传热机制主要为固体导热;在高温情况下(T>400℃),辐射成为开孔泡沫金属的主导传热机制;在低压下,气体导热可以忽略不计,但随着压力的增大,气体导热加大对传热的影响。

Energy conservation law and diffusion approximation approach were used to build the model to predict the effective thermal conductivity of open metal foam. The influences of temperature and pressure on the effective thermal conductivity were analyzed and the experiment to test the model was conducted by graphite heater. The results indicate that the effective thermal conductivity increases as temperature and pressure increases. The solid conductivity is the dominant part as temperature lower than 100℃, yet radiation is the dominant part when temperature higher than 400℃. Gas conductivity is negligible under the lower pressure and increases with pressure.