【摘要】 在1根光管、2根微肋管内运行了R1234yf两相流动冷凝换热实验,工况设定中冷凝温度为40℃、43℃、45℃,质量流量为500—900 kg/(m~2·s),换热管进出口处制冷剂干度分别为0.8—0.9、0.2—0.3。实验结果显示:传热系数随冷凝温度的降低、质量流量的增加而增大,且微肋管内传热系数均大于光管内传热系数,其中8°和15°肋片螺旋角微肋管换热强化倍率分别为2.51—2.89、3.11—3.57,均大于其面积增加比;使用关联式对管内传热系数预测时:Cavallini et al关联式对光管内传热系数预测精度最高,其预测误差范围在±8%以内,预测平均误差为0.56%;Cavallini et al关联式和Koyama et al关联式对微肋管内传热系数预测精度较高,其预测误差范围在±25%以内,两者的平均预测误差小于6%。更多还原

【Abstract】 The two-phase flow condensation heat transfer experiment of R1234 yf was performed inside one smooth tube and two micro-fin tubes in the paper, experimental condition was set as condensation temperatures of 40 ℃, 43 ℃ and 45 ℃, mass fluxes of 500—900 kg/(m~2·s), vapor qualities at the inlet and outlet of heat transfer tube of 0.8—0.9 and 0.2—0.3. Experimental results show: the heat transfer coefficient increases with decreasing condensation temperature and increasing mass flux, the heat transfer coefficient inside the micro-fin tube is larger than that of smooth tube, the heat transfer enhancement factor of micro-fin tube with fin helical angle of 8° and 15° is 2.51—2.89 and 3.11—3.57, respectively, which are greater than the area increase ratio. Correlation was used to predict the heat transfer coefficient inside the tube and it is found: Cavallini et al correlation has the highest accuracy in predicting the heat transfer coefficient inside the smooth tube with error range within ±8% and average prediction error of 0.56%; correlations of Cavallini et al and Koyama et al have relatively high in predicting the heat transfer coefficient inside the micro-fin tube with error range within ±25% and average prediction error of less than 6%.更多还原