液态金属镓微重力下的融化传热特性

相变蓄热适用于周期性热流作用下航天器内部工作单元的温度控制，但是需解决微重力环境下相变材料融化速率低的问题.鉴于液态金属高导热系数和高单位体积潜热的特点，在微重力下将液态金属作为相变材料有望提高融化速率.通过对微重力下液态金属镓融化过程的相界面演化、流线和温度分布特征进行数值研究，分析了腔体尺寸和过热度对融化过程的影响.结果表明:微重力下镓的融化过程中，热传导起主导作用；镓的融化时间比冰和正十八烷分别减少了88.3%和96.4%，储热量分别为冰和正十八烷的1.2倍和2.2倍；融化时间随过热度增加而减小，随腔体半径增大而增大.此外推导出了液相分数随无量纲时间变化的关系. 

Melting Heat Transfer Characteristics of Liquid Metal as Phase Change Material under Microgravity

Thermal energy storage is suitable for temperature control of working units in spacecraft under periodic heat flow, but it faces the problem of low melting rate of phase change materials under microgravity environment. In view of high thermal conductivity and high latent heat per unit volume of liquid metal, it is expected that the melting rate under microgravity will be increased by using liquid metal as phase change material. In the present study, the evolution of solid-liquid interface, streamline profile and temperature distribution during melting of gallium under microgravity are numerically investigated, and the influences of cavity size and superheat degree on melting process are analyzed. The results show that heat conduction plays a dominant role in the melting process of gallium under microgravity. The melting time of gallium is 88.3% and 96.4% shorter than that of ice and n-octadecane respectively, and the energy storage is 1.2 and 2.2 times of that of ice and n-octadecane respectively. The melting time decreases with the increase of superheat degree, and increases with the increase of cavity size. Meanwhile, the equation for describing the relationship between liquid fraction and dimensionless time is deduced.