R404A在水平内螺纹管中的冷凝换热研究

Condensation Heat Transfer of R404A in Horizontal Inner-Threaded Tubes

搭建单管冷凝换热实验台,以R404A为工质,在冷凝温度分别为35、40和45℃,质量流率200~1 000 kg/(m^(2)·s)范围内,对3种不同管径的内螺纹铜管(5、7和9.52 mm)进行了冷凝换热实验,分析冷凝温度、管径和制冷剂质量流率对管内侧传热系数的影响。研究表明:R404A在管内冷凝时,冷凝温度越低,管径越小制冷剂侧换热系数越大;制冷剂侧传热系数与制冷剂质量流率正相关,且随着质量流率的增大,5 mm管径螺纹管换热系数提高明显。

A single-tube test bench to study the condensation heat transfer characteristics of R404 A was constructed.The effects of different condensation temperatures,pipe diameters and refrigerant mass flow rates on the condensation heat transfer coefficient inside the tube were investigated experimentally.Experiments were carried out in three internal ribbed tubes with different diameter(5,7 and 9.52 mm).The condensation temperature was: 35、40、45 ℃,and the refrigerant mass flow rate was kept at 200~1 000 kg/(m^(2)·s).The results show that the condensation heat transfer coefficient of R404 A will increase with the decrease of condensation temperature and pipe diameter;the heat transfer coefficient of refrigerant side is positively correlated with the mass flow rate of refrigerant.And with the increase of mass flow rate,the heat transfer coefficient of 5 mm internal ribbed tube is clearly improved.