R134a在螺纹管内冷凝换热及压降特性

摘要

To investigate the effects of condensation temperature and diameter of inner-grooved tubes on flow evaporation and condensation performance of R134a, three kinds of inner-grooved tubes with different diameter (6.35,7.00 and 8.00 mm) were tested at different condensing temperatures (35, 40 and 45 ℃).The effects of condensation temperature,diameter and mass flow rate on heat transfer characteristics and pressure drop were investigated.The experimental results show that: the lower the condensation temperature, the higher the heat transfer coefficient of the refrigerant side and the greater the pressure drop.The tube with diameter of 6.35 mm has the greatest heat transfer coefficient of the refrigerant side and the greatest pressure drop.However,it has the greatest condensation heat transfer coefficient per unit drop(μ=hr/△P) and the best comprehensive performance.%为了研究冷凝温度和管径对3种内螺纹管内制冷剂R134a流动换热系数和压降的影响,对3根不同管径的内螺纹管(6.35,7.00和8.00 mm)在不同冷凝温度下(35,40和45 ℃)进行了冷凝实验.探究了冷凝温度、螺纹管直径和质流密度对换热特性及压降的影响.实验结果表明:冷凝温度越低,制冷剂侧传热系数越高,压降也越大.6.35 mm管的制冷剂侧传热系数最大,压降也最大,但单位压降冷凝传热系数μ(μ=hr/△P)最高,综合性能最佳.