疏水-超疏水组合表面倾斜管外混合蒸气冷凝过程

Experimental Investigation of Mix-vapor Condensation With Hydrophobic-Superhydrophobic Hybrid Surface on Inclined Tubes

本文在铜管外制备疏水超疏水组合表面,控制铜管和重力方向的倾角为0°、30°、45°、60°,利用高速摄像系统研究混合蒸气冷凝过程中表面润湿性和重力的协同调控机制,观测了液滴的动态特性,测量了组合表面上混合蒸气传热性能.结果表明:倾角增大,组合表面上的冷凝液滴会偏离重力方向沿着疏水环向下冲刷;倾角60°时,疏水区域的液滴会合并到相邻的上下超疏水区域;和亲水光滑铜管相比,组合表面上含不凝气30%的混合水蒸气冷凝传热随倾角度增加先下降、之后保持不变、最后升高,分别提高50%～65%(竖直)、35%～55%(倾角30°和45°)、45%～55%(倾角60°)。

In this paper, hybrid surface tubes with 4 different kinds inclined angle （0°, 30°, 45°, 60°） are designed to study the effect of surface wettability and gravity on dropwise condensation with non-condensable gases. Visual experimental system is performed to study condensation heat transfer performance and droplet dynamic characteristics by high speed camera. The results show that, hybrid surface changes condensation droplets off tracks, the droplets are deviate from the direction of gravity flushing along hydrophobic ring, with the increasing of inclined angel. The droplets on the hydrophobic region are merged into the adjacent upper and lower hydrophobic region on the inclined tube with 60°, For hydrophobic-superhydrophobic hybrid surface tubes, when the non-condensable gas content is 30%, the condensation heat transfer decreases first, and finally increases after remains constant. The measured heat flux of dropwise condensation increases by 50%-65% on the vertical tube, by 45% 55% on the inclined tube with 60° and by 35% 55% on the inclined tube with 30° and 45°, compared with that of film condensation on the hydrophilic plain tube.