An Investigation Of The Transient Performance And Its Optimizaion Of Phase Change Energy Storage-Based Heat Sinks For The Thermal Mangement Of Electronics

This paper is mainly about the effects of the performance of phase change storage-based heat sink, in the condition of relatively high heat flux, this paper systematically investigated thermal physical properties of the phase change materials (PCMs), the inclination angle of the heat sink and the internal cross fin, and the reseach work are as follows:First, lauric acid (melting temperature is43℃) was used as the PCMs, and comparisons of the performance of phase change storage-based heat sink encorperating PCMs and without PCMs (i.e. the traditional heat sink) were made. Under the heat flux of5.3～10.3W/cm2transient (the heating duration is11～30min) heating condition, results show that phase change storage-based heat sink could lower the temperature of the cooling target by40℃(from140℃to100℃), and the average effective thermal resistance (0.73℃/W) is reduced by34.2%(100W), which has great advantages.Then, effects of melting temperature of PCMs on the performance of the phase change storage-based heat sink were investigated, and this could guide the selection of appropriate melting temperature of PCMs. In this paper, two PCMs, i.e. eicosane and hexadecanol, with close thermal physical properties (k≈0.15W/m-k, Cp≈1.7kj/kg·K, L≈230kj/kg) except for melting temperature (36.2℃and46.8℃) were chosen to encorperate in the heat sink. Under the heat flux of5.3～10.3W/cm2transient (the heating duration is11～30min) heating condition, results are that heat sink encorperating hexadecanol leads to better performance, because hexadecanol have greater temperature difference to the ambient during melting, which provides greater temperature drive force. While eicosane may enable a prompt protection of the target devices.A wide range of inclination angle of heat sink from0°to90°(with an increment of15°) and a pronounced heat flux of1.22～2.46W/cm2were investigated. Results show that the inclined heat sink induces more intensive natural convection, which accelerats the melting processes, thus greatly suppress the temperature rise in the initial stage of melting. This could greatly improve the performance of the phase change storage-based heat sink, for example, if the heating power is40W and the junction temperature is75℃, the operation time of electronics compared to the horizontal case could be prolonged by67%(from480to800s).At last, hexadecanol was again used as the base liquid, composite PCMs with different carbon nano tube (CNT) concentrations (0.3%,1%and3%by mass) were made, and their thermal physical properties were measured. Results show that by adding CNT, the thermal conductivity of the composite PCMs increases (from0.25to0.33W/m·k), while the viscosity grows substantially at the same time (from6.37to>2000kg/m·s). The substantial growth of viscosity makes the natural convection in melting weakened or totally vanished. This almost offsets the enhancement of performance induced by increment of thermal conductivity, making the performance of the phase change storage-based heat sink become worse with increasing the loading of CNT. Under the heat flux of3.5～7.0W/cm2, the temperature of the cooling target is raised by at least5～10℃, and the thermal resistance is increased by17.0%(from1.12to1.31℃/W).