Condensation of steam in silicon microchannels
Condensation of steam in silicon microchannels
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DOI：
10.1016/j.icheatmasstransfer.2004.02.019
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发表时间：
2005-01-01
影响因子：
7
通讯作者：
Cheng, P
中科院分区：
文献类型：
--
作者：
Chen, YP;Cheng, P
对硅晶片上蚀刻的微通道中的蒸汽冷凝进行了可视化研究，所述< 100 >硅晶片由薄派热克斯玻璃板从顶部粘合。微通道具有梯形横截面，水力直径为75 μ m。饱和蒸汽流过这些平行的微通道，其壁在室温下通过空气的自然对流冷却。入口处的饱和蒸汽的绝对压力范围为127.5kPa至225.5kPa，出口处的大气压为约101.3kPa，冷凝物的出口温度范围为42.8 ° C至90 ° C。在微通道入口附近观察到稳定的液滴凝结。当冷凝过程沿着微通道进行时，液滴在壁上积聚。当蒸汽芯夹带并推动液滴时，其在微通道的下游处变成蒸汽和冷凝物的间歇流动。在微通道中没有观察到传统的环状流、波状流和分散流等凝结现象。基于修正的经典液滴冷凝理论，预测了液滴冷凝热流密度随微通道直径的减小而增大。在Δ T= 10 ℃时，在水力直径为75 μ m的微通道中，225.5kPa下饱和水蒸气的液滴凝结热流密度可达1200 W/cm（2）。(c)2004爱思唯尔有限公司保留所有权利。
A visualization study was performed on condensation of steam in microchannels etched in a < 100 > silicon wafer that was bonded by a thin Pyrex glass plate from the top. The microchannels had a trapezoidal cross section with a hydraulic diameter of 75 mu m. Saturated steam flowed through these parallel microchannels, whose walls were cooled by natural convection of air at room temperature. The absolute pressure of saturated steam at the inlet ranged from 127.5 kPa to 225.5 kPa, and the outlet was at atmospheric pressure at approximately 101.3 kPa with the outlet temperature of the condensate ranging from 42.8 degrees C to 90 degrees C. Stable droplet condensation was observed near the inlet of the microchannel. When the condensation process progressed along the microchannels, droplets accumulated on the wall. As the vapor core entrained and pushed the droplets, it became an intermittent flow of vapor and condensate at downstream of the microchannels. The traditional annual flow, wavy flow and dispersed flow observed during condensation in macrochannels were not observed in the microchannels. Based on a modified classical droplet condensation theory, it is predicted that the droplet condensation heat flux increases as the diameter of the microchannel is decreased. It is also predicted that the droplet condensation heat flux of saturated steam at 225.5 kPa can reach as high as 1200 W/cm(2) at Delta T= 10 degrees C in a microchannel having a hydraulic diameter of 75 mu m. (c) 2004 Elsevier Ltd. All rights reserved.