超重力下相变材料熔化过程的数值模拟

Numerical Simulation of the Influence of Hypergravity on the Melting Process of A Phase Change Material

摘要:

通过数值模拟的方法,研究了地球重力和超重力条件下相变材料(PCM)的熔化过程,分析了超重力对 PCM熔化过程的影响。采用的超重力大小为 5倍和 10倍地球重力,方向与热流进入方向相反。模拟结果表明,由于 PCM导热系数偏小,熔化初期加热面发生过热,须通过耦合其他强化换热措施予以减弱甚至消除。超重力对于PCM熔化过程的影响十分显著。随着超重力的增加,熔化界面的波动幅度增大,熔化速度加快,加热面温度下降,这是因为熔化过程中液相的自然对流作用显著增强。此外,超重力对 PCM熔化过程的增强幅度会随超重力的增加而减小,表明超重力的强化换热作用有一定限度,当超过一定值时,该强化作用的效果相对减弱。

Abstract:

The melting process of a phase change materials (PCM) under the Earth gravity and hypergravity was studied through numerical simulation method, and the influence of hypergravity on the melting process of PCM was analyzed. The hypergravity value was five and ten times of the Earth gravity, and the hypergravity direction was opposite to that of the in?coming heat flux. The simulation results indicate that the overheating occurs on the heating wall at the beginning of the melting process due to the small thermal conductivity of the PCM, other heat transfer enhancement methods should be em?ployed to weaken even eliminate the overheating. The influence of the hypergravity on melting process of the PCM was sig?nificant. The fluctuation amplitude of phase interface increases, the melting rate increases, and the temperature of the heat?ing wall decreases with the increasing hypergravity, because of the obvious enhancement of the natural convection of the liquid PCM in the melting process. In addition, the enhancement amplitude of the hypergravity on the melting process de?creases with the increasing hypergravity, implying that the enhancement of the hypergravity has a limitation, and would be weakened when the hypergravity exceeds certain values.