Transient Performance Of A Thermal Energy Storage-based Heat Sink Using Liquid Metal As The Phase Change Material

In order to assess the potential of using low-melting-point alloys in thermal management technologies that are based on phase change thermal energy storage, the transient performance of a thermal energy storage-based heat sink, where a low-melting-point alloy was adopted as the phase change material, was investigated experimentally under pulsed high heat flux conditions.A Pb-Sn-In alloy with a melting point of approximate 60 ℃ was tested in this work, and its important thermophysical properties including thermal conductivity, density, specific heat, and latent heat of fusion were characterized according to the standards such as GB/T1425-1996, ASTM E1269-2011, GB/T3850-1983 and so on. The properties was compared with those of 1-octadecanol. It was shown that the thermal conductivity of the Pb-Sn-In alloy in solid phase is about 7.1 W/m·K,26 times that of 1-octadecanol’s thermal conductivity. While the volumetric energy storage density is 2.17×105 kJ/m3,2% more than 1-octadecanol’s, indicating that this alloy has both good therwmal conductance and energy storage capacity.Then, the transient performance of the alloy-loaded heat sink at various heat fluxs(28.76、 56.12、83.64、105.32、136.99 W/cm2) were investigated, as compared to the unloaded case. It was found that the effective protection of the alloy-loaded heat sink duration for the cooling target were 512 s、140.5 s、70 s、47 s and 36.5 s. When the heat flux was 28.76 W/cm2, the effective protection duration for the cooling target was extended by about 130% for the alloy-loaded heat sink as compared to the unloaded case. This value decreased to 14% as the heat flux increased to 136.99 W/cm2. The performance improvement of the alloy-loaded heat sink was found to become less significant with the heat flux increasing.Last, the transient performances of the alloy-loaded and the 1-octadecanol-loaded heat sink were investigated and compared. When the heat flux was 28.76 W/cm2, the effective protection duration for the cooling target was extended by about 78.4% for the alloy-loaded heat sink as compared to the 1-octadecanol-loaded case. The 1-octadecanol-loaded heat sink was unworkable at the heat flux of 56.12 W/cm2, while the alloy-loaded one worked normally until the heat flux became 136.99 W/cm2. As compared to the 1-octadecanol-loaded heat sink, the alloy-loaded one has a better thermal shock resistance to work under a larger heat load and heat flux.