三角形微通道流动冷凝的实验研究

EXPERIMENTAL INVESTIGATION ON FLOW CONDENSATION IN TRIANGULAR MICROCHANNELS

实验研究了三角形硅微通道中的流动冷凝。通道中的冷凝流型沿程主要有珠状流、环状流、喷射流和弹状-泡状流等。在同一通道中,喷射流位置随着工质流量的增大而延后;在相同蒸气入口雷诺数下,喷射流位置则随着通道尺度的增大而延后。喷射流频率随着蒸气入口雷诺数和冷凝液韦伯数的增大而增大。较小水力直径的三角形通道中的流动冷凝不稳定性较高。冷凝通道的壁面温度呈沿程下降趋势。在同一通道中,流动冷凝的平均冷凝传热系数和平均努塞尔数,皆随着蒸气入口雷诺数的增大而增大,通道尺度的减小显著强化冷凝传热。

Experimental study was conducted to investigate the condensation of steam in triangular silicon microehannels. Droplet, annular, injection and slug-bubbly flow were observed along the mierochannel. With increasing mass flux, or an increase in the hydraulic diameter under the same Reynolds number, the location at which the injection occurred was observed to move towards the channel outlet. The frequency of the injection increases with increasing inlet vapor Reynolds number and condensate Weber number. The condensation instability was higher with the decrease in hydraulic diameter of channel. In addition, the temperature of the channel wall decreases along the channel. The average condensation heat transfer coefficient and the average Nusselt number were observed to be larger with increasing inlet vapor Reynolds number. More specifically, the condensation heat transfer was significantly enhanced by a reduction in the channel hydraulic diameter.