R410A和R22在小管径水平管内冷凝换热特性研究

本文搭建了冷凝换热实验台,对R410A和R22管内冷凝换热系数性能进行对比研究,实验工况为质量流速200~800kg/(m^2·s)、饱和温度40℃、干度0~1、5 mm外径水平光滑铜管,分析了质量流速和干度对管内冷凝换热的影响,并将应用于传统管道的关联式与实验所得数据进行对比。结果表明:冷凝换热表面传热系数与质量流速和干度呈正相关,高干度区域时的冷凝换热表面传热系数增幅显著;M. M. Shah[4]关联式来预测实验数据的效果并不理想,与实际值相比偏差最大可达60%,但是预测低质量流速和低干度区的数据较为理想;当质量流速较小(G=200 kg/(m^2·s))时,R410A的冷凝换热表面传热系数要低于R22;随着质量流速的增大(G=400 kg/(m^2·s)),二者冷凝换热表面传热系数的差距减小;当达到中高质量流速(G=600kg/(m^2·s))时,R410A的冷凝换热表面传热系数与R22的相似;当质量流速继续增大(G=800 kg/(m^2·s))时,R410A的冷凝换热表面传热系数随着干度的增大开始高于R22的。

Experimental Study on CoolingHeat Transfer of R410A and R22 in Small-diameter Tubes

A test rig for condensation heat transfer was developed and the cooling heat transfer characteristics of R22 and R410A in small-diameter tubes were compared. The test conditions were as follows: the mass flow rate 200-800 kg/(m^2·s),saturation temperature 40℃,the range of quality 0-1,and the outer diameter of the horizontal smooth copper tube 5 mm. The effects of the mass flow rate and quality on condensation heat transfer were analyzed and the correlation formula applied to the traditional pipeline was compared with experimental data. The analysis results showed that the condensation surface heat transfer coefficient was positively correlated with the mass flow rate and quality;in addition,the condensation surface heat transfer coefficient increased significantly in the high quality area. The M. M.Shah[4]correlation was not ideal in predicting the test data and the maximum deviation from the actual values reached 60%. However,the M. M. Shah[4] correlation was ideal for predicting data in a low mass flow rate and low quality area;when the mass flow rate(G = 200 kg/(m^2·s)) was small,the condensation surface heat transfer coefficient of R410A was lower than that of R22. Furthermore,with the increases in the mass flow rate(G = 400 kg/(m^2·s)),the disparity between the two condensation surface heat transfer coefficients decreased. The condensation surface heat transfer coefficient of R410A was similar to that of R22 when a medium to high mass flow rate(G= 600 kg/(m^2·s)) was reached. When the mass flow rate(G=800 kg/(m^2·s)) continued to increase,the condensation surface heat transfer coefficient of R410A rose higher than that of R22 as the quality increased.