Significant heat transfer enhancement for R123 condensation by micromembrane cylinder  

作　　者：Jian Xie Feng Xing Jinliang Xu Huan Liu 

机构地区：[1]The Beijing Key Laboratory of Multiphase Flow and HeatTransfer, North China Electric Power University

出　　处：《Chinese Science Bulletin》2014年第28期3676-3685,共10页

基　　金：supported by the National Natural Science Foundation of China of International Cooperation Project (51210011);the National Basic Research Program of China (2011CB710703);the National Natural Science Foundation of China (U1034004)

摘　　要：Renewable energy or low grade energy utilizations need high performance of phase change heat exchangers. Suspending micromembrane cylinder in tube(called modulated heat transfer tube) increases the void fractions or vapor qualities near the tube wall to significantly enhance heat transfer. The R123 condensation heat transfer with horizontal position was investigated. The results for the bare tube and modulated heat transfer tube were tested case by case. It is found that the modulated heat transfer tube significantly enhance the condensation heat transfer, with the heat transfer enhancement factors(EF)covering the range of 1.118–2.124. The comprehensive performance evaluation criteria(PEC) had the range of0.71–1.66, with most of runs behaving PEC larger than 1.0.For the two-phase outlet conditions, the EF values are increased with increases in the vapor mass fluxes, Gxin,where G is the mass flux and xinis the inlet vapor mass quality. The EF values are inversely related to Gxinfor the subcooled liquid outlet cases. The enhanced heat transfer mechanisms are analyzed with the observed images together with the discussion of pressure and velocity distributions.Renewable energy or low grade energy utili- zations need high performance of phase change heat exchangers. Suspending micromembrane cylinder in tube （called modulated heat transfer tube） increases the void fractions or vapor qualities near the tube wall to signifi- cantly enhance heat transfer. The R123 condensation heat transfer with horizontal position was investigated. The results for the bare tube and modulated heat transfer tube were tested case by case. It is found that the modulated heat transfer tube significantly enhance the condensation heat transfer, with the heat transfer enhancement factors （EF） covering the range of 1.118-2.124. The comprehensive performance evaluation criteria （PEC） had the range of 0.71-1.66, with most of runs behaving PEC larger than 1.0. For the two-phase outlet conditions, the EF values are increased with increases in the vapor mass fluxes, Gxin, where G is the mass flux and xin is the inlet vapor mass quality. The EF values are inversely related to Gxin for the subcooled liquid outlet cases. The enhanced heat transfer mechanisms are analyzed with the observed images toge- ther with the discussion of pressure and velocity distributions.

关 键 词：强化传热 R123 凝结 质量通量 膜 冷凝传热 综合性能 蒸汽质量 

分 类 号：TK124[动力工程及工程热物理—工程热物理] O359[动力工程及工程热物理—热能工程]