微米行程微膨胀型热开关热特性的仿真与试验

为了提高空间热控分系统的散热调节能力和热环境适应性,设计了一种微米行程的微膨胀型热开关。介绍了热开关的结构组成和工作原理,通过理论-仿真-试验相结合的方式,计算评估了热开关的断开热阻、闭合热阻和开关比等关键热特性。依据热阻网络串并联关系计算热开关的理论特性,断开热阻为301.71K/W,闭合热阻为1.06K/W,开关比约为283.6。基于有限元模型分析热开关断开/闭合过程的瞬态热特性,热端发热功率为18 W时,热开关闭合响应时间为340s,触发温度为35.5℃,闭合热阻约为2.3K/W。在2次热开关性能测试试验中,闭合热阻和开关比分别为1.08K/W、279.4和1.67K/W、180.7,试验数据与理论计算高度一致。同时指出:装配调试过程的不确定性会造成微膨胀型热开关宏观热特性的小区域波动。本文工作可为后续微膨胀型热开关的结构优化设计、机械加工细化和装调方式改进提供参考。

Simulation and experiment of thermal properties for micro-expansion type heat switch with micron stroke

To improve the heat-dissipation regulation capability and thermal environment adaptability of space thermal control subsystem, a micro-expansion type heat switch with micron stroke was designed. The structural components and operating principle of the switch were introduced, and the key thermal properties of heat switch, including OFF resistance, ON resistance and ON/OFF ratio, were evaluated by combination of theory, simulation and experiments. Theoretical thermal properties of heat switch is calculated based on the series-parallel relationship of thermal resistances, the OFF resistance and ON resistance are 301.71 K/W and 1.06 K/W, respectively, the ON/OFF ratio is about 283.6. Transient thermal properties of the OFF/ON process was analyzed by the finite element model, when the heating power of hot end is 18 W, the turn-ON response time and triggering temperature are 340 s and 35.5℃, and the ON resistance is about 2.3 K/W. Moreover, in the twice property experiments,the ON resistance and ON/OFF ratio are 1.08 K/W, 279.4 and 1.67 K/W, 180.7 respectively,and experimental data is in agreement with the theoretical calculations well. The experimental results point out that the uncertainty of assembly-regulation process would cause small interval fluctuations of macro thermal properties of the heat switch, The conclusions cloud provide references for structural optimization design, machining refinement and assembly-regulation improvement of subsequent micro-expansion type heat switches.