Abstract
In the present work, a new simulation of nanofluid/vapor two-phase flow inside the 2-D rectangular boiling chamber was numerically investigated. The Eulerian–Eulerian approach used to predict the boiling curve and the interaction between two phases. The surface modification during pool boiling of silica nanofluid represented by surface roughness and wettability is put into the account in this simulation. New closure correlations regarding the nucleation sites density and bubble departure diameter during boiling of silica nanofluid were inserted to extend the boiling model in this work. Besides, the bubble waiting time coefficient which involved in quenching heat flux under heat flux partitioning HFP model was corrected to improve the results of this study. The numerical results validated with experimental works in the literature, and they revealed good agreements for both pure water and nanofluids. The results found that when improving the heat flux partitioning model HFP by considering the surface modification of nucleate pool boiling parameters, it will give more mechanistic sights compared to the classical model, which is used for predicting of boiling heat transfer of pure liquid.
Highlights
During the last decades, considerable efforts have been made by experts of thermofluids and heat transfer to investigate the boiling heat transfer process
It can be clearly seen from the curves that the HTC for nanofluids was degraded compared to pure water especially for high heat flux values and this trend noted by experimental data of [37], while the finding of [40] detected that the nanofluids could enhance the heat transfer coefficient and this contradictory in results may be due to the type of nanofluids and the thermophysical properties that be used in their studies as well the
In the case of nanofluid, the numerical model was integrated with user-defined functions UDFs for boiling parameters such as bubble-departure diameter and nucleation site density to take into account the surface modification during pool boiling of nanofluid
Summary
Considerable efforts have been made by experts of thermofluids and heat transfer to investigate the boiling heat transfer process. Efforts are going on to conduct more experimental investigations to get extensive empirical or semi-empirical correlations regard to heat and mass transfer during pool boiling of nanofluids and their sub phenomena such as bubbles dynamic, surface interaction and transient conduction to build a robust model. In this simulation, efforts have been made to predict the nucleate pool boiling heat transfer mechanism using a boiling model under a two-phase Eulerian approach, which included and implemented new closure correlations related to boiling parameters such as bubble departure diameter, nucleation site density from experimental work in the literature. The following mixture of thermal properties correlations of nanofluids utilized in the present work
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