微尺度通道内R134a的冷凝传热实验研究

建立采用射流冲击进行制冷剂冷却的冷凝传热实验系统，对当量直径为0.63 mm矩形微尺度通道内制冷剂R134a的冷凝传热特性进行研究。实验参数范围是制冷剂干度0~1，质量流率115~290 kg/(m²·s），饱和压力0.35~0.5 MPa，实验获得了不同工况下微尺度通道的局部冷凝传热系数，并分析了制冷剂各参数对冷凝传热的影响。实验结果表明：冷凝过程中沿制冷剂流动方向，局部冷凝传热系数会随着干度减小而减小；在一定饱和压力下，局部冷凝传热系数与局部热通量相对应；冷凝传热系数随着饱和压力减小而增大。基于实验数据，整理出适用于本实验工况下微尺度通道内R134a的冷凝传热计算公式。

Experimental investigation on condensation heat transfer of refrigerant R134a in micro-scale channel

A condensation heat transfer test system was built to investigate the condensation heat transfer characteristics of R134a flowing inside one multi-port extruded tube with the hydraulic diameters of 0.63 mm, and a jet impingement cooling method was used to condense superheated refrigerant. The experiments were performed at vapor quality between 0 and 1, mass flow rate of refrigerant between 115 and 290 kg/(m²·s), saturation pressure between 0.35 MPa and 0.5 MPa. The local condensation heat transfer coefficients of the tube under different working conditions were obtained, and the influences of several factors on condensation heat transfer were analyzed. The experimental results show that, in condensation process, the local condensation heat transfer coefficient will decrease with the decrease in vapor quality. At a certain saturation pressure, the condensation heat transfer coefficient and local heat flux are corresponding to each other. The condensation heat transfer coefficient will increase with the decrease in saturation pressure. On the basis of the experimental data, a new correlation is proposed to calculate condensation heat transfer coefficients of refrigerant R134a in the multi-port extruded tubes in experimental conditions.