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

Georgia Tech Research Corporation, Atlanta GA

Investigators

Abstract

1511470 - Grigoriev The 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.