竖直槽道内蒸气向上流动凝结换热的实验研究

Experimental Study on Vapor Flowing Upward Condensation in a Vertical Channel

通过高速摄影仪拍摄手段,观察了制冷剂R410A蒸气在水力直径为14.34mm、长度为160mm的竖直矩形槽道内垂直向上流动凝结过程中壁面液膜的流动特征.实验结果表明:在饱和温度为28℃和质量流速范围为1.8~23kg·m^(-2)·s^(-1)实验条件下,随着质量流速的增大,壁面出现假滴状流动和层流波状流动,并且随着质量流速的增大凝结液膜逐渐增厚,液膜表面波动亦更加明显;槽道内的平均凝结换热系数随质量流速的增大出现先增大后减小的趋势.实验得到了槽道壁面测温点分割出的四段壁面的各段的平均凝结换热系数的沿槽道轴向的变化情况.

The liquid film flowing characteristics of new refrigerant R410 A flowing upward condensation in a vertical rectangular channel were observed by high speed camera. The saturation temperature of refrigerant R410 A vapor is 28℃. The hydraulic diameter of the rectangular channel is 14. 34 mm and the length is 160 mm. The test was conducted at mass fluxes 1. 8 ~ 23kg·m^(-2)·s^(-1).It is shown that tadpole flow and laminar wave flow occurred with the increase of mass flux.The thickness of the liquid film and the wave frequency were found to be increased and enhanced with increasing mass flux. The average condensation heat transfer coefficient increases at first,and then decreases with mass flux.Also,the variation of the average condensation heat transfer coefficients of the different segments divided by the temperature measuring points with the different segments of the channel were obtained.