R22在水平微肋管和光管内凝结换热的实验研究

Experimental investigation on condensation heat transfer in horizontal microfin and smooth tube with refrigerant R22

进行了R22在光管和微肋管内凝结换热实验，比较了局部换热系数．这两种管具有同样的外径9mm，实验段有效换热长度1104mm，微肋管是以同样尺寸的光管为坯管加工而成．实验工况对应凝结换热温度38．6℃，工质流量分别为30kg／h，60kg／h，干度范围0．2～0．8，热流密度15kW／m^2．实验结果表明，与光管相比，微肋管的换热系数是光管的1．7倍左右．但微肋管的强化效果在不同的管内工质流量下有所不同，在较小流量30kg／h下，微肋管强化效果在不同干度下差别不大，但在较大流量60kg／h下，强化效果随着干度的增大而增强．

Local condensation heat transfer of R22 in a microfin tube and a plain tube are measured and compared. The two tubes have the same outer diameter of 9 mm, the active length of test tube is 1 104 mm, microfin tube is manufactured from the same plain tube. The test was measured at the condensation temperature of 38.6℃ with mass flux of 30 kg/h and 60 kg/h, quality of 0.2 - 0.8, and the constant heat flux of 15 kW/m^2. The result indicates that the local heat transfer coefficients of microfin tube are about 1.7 times of those of the plain tube. But the enhancement of heat transfer coefficient is different with refrigerants mass flux. At lower refrigerant mass flux 30 kg/h, the augmentation of heat transfer is the same at different quality while increases with quality increase at higher mass flux 60 kg/h.