【摘要】 为研究HFOs制冷剂R1234ze(E)与HFCs制冷剂R134a在Y型翅内螺纹双侧强化管管外降膜蒸发的换热性能,搭建了水平管降膜蒸发换热性能测试实验台,分别在不同的管内水速、喷淋密度、热流密度以及蒸发温度条件下进行了实验,利用Wilson-Gnielinski图解法分离管内外的换热系数,得到了2种制冷工质管外降膜蒸发时的换热特性。实验数据分析表明:该强化管管内换热的强化倍率为2.34,2种制冷剂的总传热系数K和管外换热系数h_o均随着制冷剂喷淋密度的增加呈现先升高再略有降低的趋势;随热流密度的增加呈现降低趋势;随蒸发温度的增加呈现增加趋势,但变化量较小。R1234ze(E)的管外降膜蒸发换热系数略高于R134a。更多还原

【Abstract】 To study the falling film evaporation heat transfer performance of HFOs refrigerant R1234 ze(E) and HFCs refrigerant R134 a outside the double-sided enhancement tube which has threaded fins inside the tube and Y-shaped fins outside the tube, an experimental platform was set up for measuring the falling film evaporation heat transfer coefficient of horizontal tube. Experiments were carried out under different water velocity, spray amount, heat flux and evaporation temperature. The heat transfer coefficient inside and outside the tube were separated by Wilson-Gnielinski graphic method, and the heat transfer performance of falling film evaporation outside the tube was obtained for two refrigerants. The experimental data analysis shows that the heat transfer enhancement ratio inside this tube is 2.34. The K and h_o outside the tube of the two refrigerants first increase and then slightly decrease with the increase of spray amount of refrigerant, decrease with the increase of heat flux, and increase with the increase of evaporation temperature, but the change is small. The falling film evaporation HTC of R1234 ze(E) is slightly higher than that of R134 a.更多还原