Parametric Effects on Pool Boiling Heat Transfer and Critical Heat Flux: A Critical Review

Abstract

Pool boiling heat transfer offers high-performance cooling opportunities for thermal problems of electronics limited with high heat fluxes. Therefore, many researchers have been extensively studying over the last six decades. This paper presents a critical literature review of various parametric effects on pool boiling heat transfer and CHF such as pressure, subcooling, surface topography, surface orientation, working fluid, and combined effects. To achieve an optimal heat removal solution for a particular problem, each of these parameters must be understood. The governing mechanisms are discussed separately, and various options related to the selection of appropriate working fluids are highlighted. A broad summary of correlations developed until now for predicting critical heat flux (CHF) is presented with their ranges of validity. While proposed correlations for predicting CHF has been quite promising, they still have a considerable uncertainty (±25%). Finally, a correlation proposed by Professor Avram Bar-Cohen and his team (TME correlation) is compared with the experimental data set published in previous studies. It shows that the uncertainty band can be further narrowed down to ±12.5% for dielectric liquids by using TME correlation. Furthermore, this correlation has been enhanced to predict CHF values underwater above 50 W/cm2 by applying a genetic algorithm, and new perspectives for possible future research activities are proposed.

The Influence of Pressure on Local Heat Transfer Rate under the Vapor Bubbles during Pool Boiling

“…Pressure is one of the most important parameters in a boiling system, the change in which has a complex effect on the nucleation, dynamics of vapor bubbles, heat transfer rate and the development of boiling crisis phenomena. At the same time, it is known that the pressure reduction below atmospheric level leads not only to a quantitative, but also to a qualitative change in the boiling character [21][22][23][24][25]. In particular, a decrease in pressure is accompanied by a decrease in the intensity of heat transfer and a decrease in the critical heat flux, the nucleation of bubbles becomes more unstable and takes place at larger surface superheating.…”