UNS: Fundamental Studies of Two-Phase Flows of Binary Fluids Driven by Temperature Gradients

1511470 -Grigoriev主要研究人员建议开发一种理论模型，其中蒸汽在表面上的冷凝显着增加传热速率。 如果该模型成功，它可以帮助理解增强传热的机制，并导致设计更节能的能源处理设备。 该模型将通过相应的实验来验证。 这个由理论家和实验家组成的团队提出开发数值模型，并通过实验验证它们在多相流中增强相变传热的二元流体的应用。这项工作建立在最近的研究，涉及多相流，但增加了复杂的方法与伪滴状和膜状冷凝。 这些方法是新颖的，在根本上不同于以前对这一主题的研究。 本计画将研究在水平温度梯度驱动下，挥发性受限二元流体层中的对流。 传输模型的目的是准确地预测传热增强，并确定所需的具体条件（液体成分，最大水平的不可冷凝物，过冷或温度梯度），以最大限度地提高这种增强。 考虑了不凝物存在和不存在时二元混合物蒸汽的冷凝问题。由于由浓度梯度引起的有利的表面张力梯度（与马兰戈尼对流中不利的表面张力梯度相反），优选滴状冷凝。主要研究人员认为，有利的表面张力梯度可以减轻蒸发过程中干点的形成。

1511470 - GrigorievThe principal investigators propose to develop a theoretical model where condensation of vapor on a surface significantly increases heat transfer rates. If the model is successful, it can help understand the mechanism of enhanced heat transfer and lead to design of more energy-efficient energy handling devices. The model will be verified by the accompanied experimental efforts. This team of a theoretician and an experimentalist propose to develop numerical models and experimentally validate them for application of binary fluids in enhancing phase change heat transfer in multi-phase flows. The work builds on recent research involving multi-phase flows but adds complex approaches with pseudo-dropwise and film condensation. The approaches are novel and different in fundamental ways from prior research on the topic. This project will investigate convection in volatile confined binary-fluid layers driven by a horizontal temperature gradient. The transport model is aimed to accurately predict heat transfer enhancement and determine the specific conditions (in terms of liquid composition, maximum level of noncondensables, and subcooling or temperature gradient) required to maximize this enhancement. Condensation of binary mixture vapor both in the presence and absence of non-condensables is considered. Due to the favorable surface tension gradient (as opposed to the unfavorable surface tension gradient as in Marangoni convection) caused by concentration gradient, dropwise condensation is preferred. The principal investigators suggested that the favorable surface tension gradient can mitigate dry spot formation during evaporation.