Effects of superheat and temperature-dependent thermophysical properties on evaporating thin liquid films in microchannels
Effects of superheat and temperature-dependent thermophysical properties on evaporating thin liquid films in microchannels
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DOI：
10.1016/j.ijheatmasstransfer.2010.10.026
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发表时间：
2011-02
影响因子：
5.2
通讯作者：
Jun-jie Zhao;Y. Duan;Xiao-Dong Wang;B. Wang
中科院分区：
文献类型：
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作者：
Jun-jie Zhao;Y. Duan;Xiao-Dong Wang;B. Wang
开发了一个基于增强杨-拉普拉斯方程和克劳修斯-克拉佩龙方程的模型来描述微通道中扩展的蒸发弯液面。模型中包含了壁过热度高达 50K 时吸附膜厚度、通道高度和流体与温度相关的热物理性质的影响。液体流与蒸气流耦合以获得穿过液-气界面的质量传递。结果表明，与可变热物理性质模型相比，恒定热物理性质模型大大高估了较高过热度下的液体压差和总薄膜传热速率。吸附膜厚度由分离压力极限控制，在水的过热度约 20K 附近达到最小值。当过热度大于 20K 时，最大膜曲率和液体压差降低。通道高度产生的毛细管压力限制的影响可以通过增加过热度来减小。
A model based on the augmented Young–Laplace equation and the Clausius–Clapeyron equation was developed to describe the extended evaporating meniscus in a microchannel. The effects of the adsorbed film thickness, channel height and temperature-dependent thermophysical properties of the fluid are included in the model at wall superheats up to 50K. The liquid flow is coupled with the vapor flow to obtain the mass transport across the liquid–vapor interface. The results show that the constant thermophysical property model greatly overestimates the liquid pressure difference and the total thin film heat transfer rate at higher superheats compared with the variable thermophysical property model. The adsorbed film thickness, which is controlled by the disjoining pressure limit, reaches a minimum near about 20K superheat for water. The maximum film curvature and liquid pressure difference then decrease at superheats larger than 20K. The effects of the capillary pressure limit produced by the channel height can be reduced by increasing the superheat.