R410A在水平强化管外蒸发换热特性研究

Study on Evaporation Heat Transfer Characteristics of R410A outside the Horizontal Enhanced Tubes

搭建了一个单管管外流动蒸发换热实验台,研究工质R410A在两种双侧强化管外流动蒸发换热特性。实验段分别为一根长2 000 mm,外径为25.4 mm的光滑管和两根相同尺寸的双侧强化管。实验工况:蒸发饱和温度为5~10℃,水的进口温度为8~18℃,水流量为0.6~1.6 m^(3)/h。在处理数据过程中采用G-W图解法获得管内水侧对流换热系数,再利用热阻分离法获得管外蒸发换热系数。结果表明:与光滑管表面传热系数相比,TLD型管的管内、管外强化倍率分别为3.49~3.7和4.78~8.86;EX2型管的管内、管外强化倍率分别为3.25~3.68和5.9~9.23;EX2型管管外换热性能较好,TLD型管管内换热性能较好。

The heat transfer performance of two types of double-side enhanced tubes is experimentally studied using R410 A by applying the horizontal single-tube flow evaporating test bench.The research object consists of a smooth tube with a length of 2 000 mm and an outer diameter of 25.4 mm and two double-side enhanced tubes of the same size.The experimental conditions are as follows: the evaporation saturation temperature is 5~10 ℃,the inlet temperature of water is 8~18 ℃,and the flow rate of water is 0.6~1.6 m^(3)/h.In the process of data processing, the G-W method is adopted to obtain the heat transfer coefficient of water-side in the tube, and the evaporation heat transfer coefficient of the refrigerant-side in the tube is obtained by thermal resistance separation method.The research shows that the enhancement ratio of the inside and outside of the TLD tube is 3.49~3.7 and 4.78~8.86,respectively, while that with the EX2 tube is 3.25~3.68 and 5.9~9.23,compared with the heat transfer coefficient on the surface of the smooth tube.The outside heat transfer performance of EX2 tube is better, and the inside heat transfer performance of TLD is better.