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

1511470-Grigoriv首席研究人员建议开发一个理论模型，在该模型中，蒸汽在表面上的冷凝显著增加了热传递速率。如果模型成功，将有助于理解强化换热的机理，并指导设计更节能的能量处理装置。该模型将通过伴随的实验工作进行验证。这个由理论家和实验学家组成的团队提议开发数值模型，并通过实验验证它们在应用二元流体强化多相流中的相变换热方面的应用。这项工作建立在涉及多相流的最新研究基础上，但增加了伪滴状和膜状冷凝的复杂方法。这些方法是新颖的，在根本上不同于以前对该主题的研究。该项目将研究由水平温度梯度驱动的挥发性受限双流体层中的对流。输送模型的目的是准确地预测强化换热，并确定最大化强化换热所需的特定条件(根据液体组成、最大不凝结物水平以及过冷或温度梯度)。研究了在存在和不存在不可冷凝物的情况下二元混合物蒸汽的冷凝过程。由于浓度梯度产生了有利的表面张力梯度(而不是Marangoni对流中的不利表面张力梯度)，因此滴状冷凝是首选。主要研究人员认为，良好的表面张力梯度可以减缓蒸发过程中干斑的形成。

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.