This paper studies the evaporation heat transfer of R32 inside two different diameters of horizontal tubes under saturation tem-peratures of 0℃, 5℃, and 10℃. The evaporation heat transfer coefficient of the refrigerant was obtained by using a heat resistance sep-arating method. Taking mass flux and saturation temperature as the influencing factors, the experiment results include two parts:analysis of single-tube thermal resistance and evaluation of single-tube comprehensive performance. The experimental results indicate that the heat transfer coefficient and pressure drop rise as the mass flux rate increases. The diameter has a great influence on the heat transfer coeffi-cient, and the heat transfer coefficient of No. 1 is 1. 1~1. 3 times as that of No. 2. The effect of temperature on the heat transfer coeffi-cient and the pressure drop differs under different mass flux rate. As the mass flux rate increases, the proportion of the external water side-tube resistance to the total thermal resistance increases, while that of the inside gradually decreases. The heat transfer coefficient per pres-sure drop of two single tubes decreases as the mass flux rate increases. The saturation temperature shows various effects on the parameters at different mass flux rate.%本文对2根不同孔径单管在饱和温度分别为0℃、5℃和10℃工况下进行水平管内R32蒸发换热的实验研究.采用热阻分离法得到管内制冷剂侧蒸发传热系数,以质量流量、饱和温度为影响因子,对实验结果进行单管热阻分析及综合性能评价.结果表明:管内传热系数及压降均随着质量流量的增加而增加,管径对传热系数影响较大,1#传热系数约为2#的1.1~1.3倍,不同质量流量下温度对传热系数及压降的影响比重不同;随着质量流量的增加,管外水侧热阻占总热阻的比例逐渐增大,管内制冷剂侧热阻占总阻值的比例逐渐减小;两根单管单位压降传热系数均随质量流量的增加而减小,在不同质量流量下饱和温度对参数的影响比重不同.
展开▼
