摘要
对非共沸混合制冷剂R32 R134a(2 5 %Wt 75 %Wt)在水平内螺纹强化管中的流动沸腾换热特性进行了研究。实验结果表明 :在内螺纹强化管中的流动沸腾换热性能比在光管中有较明显的提高 ;强化管强化系数变化的大致范围为 1.5～ 2 .2。根据活化穴、二次流和毛细提升三者之间的相互作用 ,探讨了内螺纹强化管的强化机理 ;并从重力影响、非共沸混合工质组分差与二次流影响的角度上 ,对在环状流下混合工质R32 R134a在内螺纹强化管和光管中流动沸腾换热时管子周向壁温的变化特征作出了分析。
Experimental study is reported for heat transfer in forced convective boiling of a nonazeotropic mixture of R32/R134a (25%Wt/75%Wt) inside both smooth and microfin tubes with internal spiral grooves. The experimental results show that the microfin tubes have distinct performance advantages over the smooth tube at similar conditions. Considerating the interaction effects among nucleation sites, secondary flow and capillary promotion, this paper describes the enhanced mechanism for the microfin tubes, and the circumferential wall temperature variation of R32/R134a in the annular flow regime was observed and analyzed for both smooth and microfin tubes, which caused by the composition concentration variation, gravity and secondary flow.
出处
《制冷学报》
CAS
CSCD
北大核心
2003年第1期13-17,共5页
Journal of Refrigeration
关键词
R32
R134A
水平内螺纹管
沸腾强化换热
实验研究
非共沸混合制冷剂
环状流
周向壁温
refrigeration and cryogenic engineering, nonazeotropic refrigerant mixture, forced convective heat transfer, microfin tubes, annular flow, circumferential wall temperature
