微肋管内流动冷凝压降关联式的研究

Research on Correlation of the Flow Condensation Pressure Drop inside the Micro-fin Tube

本文进行了微肋管内R134a两相流动冷凝换热实验,分析了实验工况、微肋管结构参数对管内压降的影响,并使用关联式对管内压降进行了预测。实验结果显示:管内压降与质量速率、肋片螺旋角呈正相关,与冷凝温度、冷却水雷诺数Re呈负相关;Cavallini et al关联式、Haraguchi et al关联式、Pierre关联式可实现对管内压降的高精度预测,预测平均误差均在17%以内,而Goto et al关联式高估了管内压降;参考Goto et al关联式拟合机理,基于微肋管内R134a压降实验数据,对气相/液相折算系数Φv/Φl与参数Xtt之间关系进行重新拟合,进而提出适用于预测管内压降的关联式,经验证:新关联式预测误差在±30%以内,预测平均误差小于10%。

The two-phase flow-condensation heat transfer experiment of R134a inside the micro-fin tube was operated on the test bench,the influence of working conditions and micro-fin tube structural parameters on the pressure drop was studied,and its correlations were also used to predict the pressure drop inside the tube in this study.The experimental results show that the pressure drop is positively correlated with mass flux and fin helical angle;however,they are negatively correlated with condensation temperature and Re of cooling water.Correlations of Cavallini et al.,Haraguchi et al.,and Pierre have good predictive effects on the pressure drop with an average prediction error of less than 17%,while the correlation Goto et al.overestimates the pressure drop.Based on the pressure drop experimental data of R134a,the functional relationship betweenΦv/Φl and Xtt was fitted again and referred to the computing mechanism of Goto et al.for correlation.Then,a new correlation for predicting the pressure drop inside the tube is put forward,and statistic test shows that the prediction error of the new correlation is within±30%and the average prediction error is less than 10%.