间歇性大功率相变热沉研究

针对某300W大功率间歇式热源，选用9wt%膨胀石墨-56号石蜡复合材料作相变工质，铝翅片作导热结构，基于Fluent软件，采用等效比热容数学模型，在安全温度为65℃情况下，设计得到能稳定运行3500s的相变热沉。针对该相变热沉，为验证等效比热容数学模型的可靠性，搭建了相变热沉测试系统，研究了热源功率及相变工质对热沉控温性能的影响。结果表明：等效比热容数学模型有效可靠；相变材料熔点越低，相变热沉温控时间越长；而热源输入功率越高，相变工质熔点的影响将变小。此外，为降低系统内部温差、减少石蜡泄露以及降低加工成本，进一步提出了热管-回转式翅片相变热沉，热管-回转式翅片相变热沉在热源功率为300W条件下，温控时间高达4300s，内部温差仅在1.6℃以内。

Research of intermittent high power phase change heat sink

For a 300W high-power intermittent heat source, 9wt% expanded graphite-56 paraffin composite was used as phase change working medium, and aluminum fins were used as heat-conducting structure. Based on Fluent software and the equivalent specific heat capacity mathematical model, a phase change heat sink capable of stable operation of 3500s is designed at a safe temperature of 65 °C. Furthermore, a phase change heat sink test system was established to verify the reliability of the equivalent specific heat capacity mathematical model. Besides, the effects of heat source power and phase change working fluid on the temperature control performance of the heat sink were studied. The results show that the mathematical model of equivalent specific heat capacity is effective and reliable; the lower the melting point of phase change material, the longer the temperature control time of phase change heat sink; and the higher the in-put power of heat source, the smaller the influence of melting point of phase change working medium. In addition, in order to reduce the internal temperature difference of the system, the leakage of paraffin and the processing cost, the heat pipe - rotary fin phase change heat sink are further proposed. Under the con-dition of input power of 300W, the heat pipe - rotary fin phase change heat sink could work safely for 4300s, and internal temperature difference is within 1.6 °C.