Numerical Simulation of Laminar Liquid Film Condensation in a Horizontal Circular Minichannel
Numerical Simulation of Laminar Liquid Film Condensation in a Horizontal Circular Minichannel
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DOI：
10.1115/1.4005710
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发表时间：
2012-05
影响因子：
--
通讯作者：
E. D. Riva;D. Col
中科院分区：
文献类型：
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作者：
E. D. Riva;D. Col
采用三维流体体积法（VOF）模拟了R134 a在内径为1 mm的平板内的冷凝过程。微通道介绍。微通道是水平定向的，并且考虑了重力的影响。在考虑和不考虑表面张力的情况下进行了模拟。边界条件为均匀的界面温度和均匀的壁面温度。质量通量为G = 100 kg m−2 s−1，假设液相内为层流，而气相内的湍流由k-ω模型的修正低雷诺数形式处理。将流体冷凝至0.45蒸汽干度。预计流动是环形的，没有波的存在，因此该问题被视为稳定状态。计算结果显示的汽液界面和传热系数的演变报告和验证实验数据。凝聚过程被发现是重力为主，而全球的表面张力的影响被发现是可以忽略不计的。在入口处，液膜很薄，均匀地分布在管圆周周围。向通道的下游移动，膜厚度在微通道的上半部分中保持几乎恒定，而在管的底部处的膜变得更厚，因为在顶部处冷凝的液体通过重力排出到底部。
A three-dimensional volume of fluid (VOF) simulation of condensation of R134a inside a 1 mm i.d. minichannel is presented. The minichannel is horizontally oriented and the effect of gravity is taken into account. Simulations have been run both with and without taking into account surface tension. A uniform interface temperature and a uniform wall temperature have been fixed as boundary conditions. The mass flux is G = 100 kg m−2 s−1 and it has been assumed that the flow is laminar inside the liquid phase while turbulence inside the vapor phase has been handled by a modified low Reynolds form of the k–ω model. The fluid is condensed till reaching 0.45 vapor quality. The flow is expected to be annular without the presence of waves, therefore the problem was treated as steady state. Computational results displaying the evolution of vapor–liquid interface and heat transfer coefficient are reported and validated against experimental data. The condensation process is found to be gravity dominated, while the global effect of surface tension is found to be negligible. At inlet, the liquid film is thin and evenly distributed all around the tube circumference. Moving downstream the channel, the film thickness remains almost constant in the upper half of the minichannel, while the film at the bottom of the pipe becomes thicker because the liquid condensed at the top is drained by gravity to the bottom.