基于纳米多孔薄膜的蒸发特性  

Evaporation processes from nanoporous membranes

作　　者：王佳豪 夏国栋[1] 李冉[1] 马丹丹[1] WANG Jiahao;XIA Guodong;LI Ran;MA Dandan(Key Laboratory of Enhanced Heat Transfer and Energy Conservation,Ministry of Education,Beijing Key Laboratory of Heat Transfer and Energy Conversion,Faculty of Environment and Life,Beijing University of Technology,Beijing 100124,China)

机构地区：[1]北京工业大学环境与生命学部强化传热与过程节能教育部重点实验室暨传热与能源利用北京市重点实验室,北京100124

出　　处：《航空动力学报》2022年第5期1113-1120,共8页Journal of Aerospace Power

基　　金：国家自然科学基金(51976002)。

摘　　要：实验研究了基于纳米多孔薄膜的蒸发特性,以氟化液FC-72为液态工质,对比分析了开口向上和向下时的相变特性。结果发现:两种工况下,其热流密度-过热度曲线具有相似的变化趋势,且均出现热流密度增加而温度保持不变的“薄液膜蒸发”区间。在低热流密度下,温度均较为稳定,但开口向下时的传热性能始终优于开口向上时,分析原因为重力对供液的影响和液膜厚度对热阻的改变。随着热流密度的增加,表面温度波动也越来越剧烈,甚至出现了温度的峰值,最终开口向下和向上达到的临界热流密度值分别为59 W/cm^(2)和47W/cm^(2);同时,对蒸发过程进行理论建模,得出其蒸发系数分别为0.043 1和0.021 9。Tests were conducted to study the evaporation processes from nanoporous membranes using FC-72. The heat transfer characteristics of two facing directions:membrane facing upward and downward, were compared. Results showed that the heat flux-superheat curves for two directions presented a similar variation trend, and there existed a ‘thin film evaporation’stage where heat flux increased while temperature remained constant. The temperature was stable in low heat flux. The heat transfer performance of downward-facing membrane was better than that of upward-facing membrane at different heat flux levels. This was caused by the effect of gravity on the liquid supply and the effect of liquid film thickness on thermal resistance. As the heat flux increased, the temperature fluctuated more sharply, eventually a temperature peak appeared. The critical heat flux reached 59 W/cm^(2)and 47 W/cm^(2)for downward and upward facing membranes, respectively. Additionally, theoretical modeling of the evaporation processes was carried out,and it was found that the evaporation coefficients were 0. 043 1 and 0. 021 9,respectively.

关 键 词：蒸发 纳米多孔薄膜 开口方向 传热特性 温度不稳定性 

分 类 号：V231.1[航空宇航科学与技术—航空宇航推进理论与工程] TK124[动力工程及工程热物理—工程热物理]