微圆管内R1234ze(E)流动沸腾的环状流特性模拟研究  

Simulation on Annular Flow of R1234ze(E)Flow Boiling in Micro-tubes

作　　者：王金[1] 李俊明[1] Wang Jin;Li Junming(Key Laboratory for Thermal Science and Power Engineering of Ministry of Education,Beijing Key Laboratory of CO<2>Utilization and Reduction Technology,Department of Energy and Power Engineering,Tsinghua University,Beijing,100084,China)

机构地区：[1]清华大学能源与动力工程系,清华大学热科学与动力工程教育部重点实验室,二氧化碳资源化利用与减排技术北京市重点实验室,北京100084

出　　处：《制冷学报》2020年第5期29-34,共6页Journal of Refrigeration

基　　金：国家重点研发计划项目(2016YFE0133300);欧盟玛丽居里国际合作交流项目(EU H2020—MSCA-RISE-2016-734340--DEW-COOL-4-CDC)资助。

摘　　要：本文建立了制冷剂R1234ze(E)在微圆管内流动沸腾过程中的环状流模型,对传热和气液两相流动压降进行了模拟研究。综合考虑重力、表面张力及气液界面剪切力的影响,模拟分析了周向液膜不均匀分布特性及该特性对流动与换热的影响,经验证,计算结果与已有实验结果吻合较好。本文还研究了不同因素对环状流区域表面传热系数与压降的影响。模拟结果表明:在流动起始区域,截面液膜厚度的分布受重力作用影响,随着流动沸腾过程的进行,该影响作用开始减弱,且有重力作用时的环状流平均表面传热系数高于无重力作用时的环状流平均表面传热系数,随着重力加速度的增加,环状流的平均表面传热系数不断增大;随着质量流速的增大,表面传热系数与压降均随之增大;随着管径增大,表面传热系数与压降均随之减小。A theoretical model for annular flow of R1234ze(E)flow boiling in micro-tubes was proposed in this paper.The surface coefficient of heat transfer and pressure drop were calculated using the model.The variation in the liquid film thickness profile due to the gravitational effect,surface tension,and liquid-vapor interfacial stress was considered.The effect of the variation in the liquid film thickness profile on the heat transfer was analyzed.Furthermore,certain existing surface coefficients of heat transfer and empirical correlations of two-phase friction pressure drop were compared with the numerical results,and the comparison revealed deviations within 30%.The numerical results indicated that the variation in the liquid film thickness profile is evidently affected by gravity in the initial flow area,and the gravitational effect starts to weaken with the flow boiling process.The surface coefficient of heat transfer of annular flow with gravity was higher than that without gravity.Hence,the mean surface coefficient of heat transfer increased with gravitational acceleration.Furthermore,surface coefficient of heat transfer and pressure drop increased as the mass flux increased.Conversely,surface coefficient of heat transfer and pressure drop decreased as the diameters increased.

关 键 词：微圆管 流动沸腾 环状流 R1234ze(E) 

分 类 号：TB612[一般工业技术—制冷工程] TK124[动力工程及工程热物理—工程热物理]