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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.
Through the means of high-speed camera shooting, the flow characteristics of the wall liquid film in the R410A vapor vertical vertical flow channel with hydraulic diameter of 14.34mm and length of 160mm were observed.The experimental results show that when the saturated temperature is Under 28 ℃ and mass flow rate range of 1.8 ~ 23kg · m ~ (-2) · s ~ (-1), droplet flow and laminar wavy flow appear on the wall with mass flow rate increasing, With the increase of mass flow rate, the condensate film gradually thickens and the surface of the liquid film is more obviously fluctuated. The average condensation heat transfer coefficient in the channel increases first and then decreases with the increasing of the mass flow rate. The average condensing heat transfer coefficient of each section of the four sections divided by the wall temperature measurement points changes along the channel axis.