Mechanistic model of bubble dynamics at subcooled boiling conditions

Jiao, Hong
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Podowski, M.
Ji, Wei
Peles, Yoav
Bolotnov, Igor
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Mechanical engineering
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The subject of subcooled flow boiling analysis encompasses a wide range of topics. A literature review suggests that several important aspects of subcooled boiling need further understanding, such as the bubble growth rate, departure point and maximum size, condensation in subcooled liquid, heat transfer in general, critical heat flux, etc. The proposed NPHASE/Level-Set modeling package has been used to simulate several phenomena in this area. Simulations of bubble condensation/evaporation after departure have been first carried out, combined with a stand-alone numerical analysis of local Nussselt number variations for flow over different shapes, such as ellipsoids and spheres. The comparison with experimental data has shown good agreement. Simulations of multiple bubbles flows have also been conducted. Concerning the issue of bubble shape before departure, the results from the NPHASE/Level Set Method and the Young-Laplace-based theoretical model have been compared against each other, showing very good agreement. Then, simulations of bubble growth on a heated surface have been carried out. These simulations demonstrated the robustness of the new algorithm for the modeling of simultaneous evaporation and condensation, as well as the capability of the package to capture several subcooled boiling phenomena before and after bubble departure. One can expect that in the future the proposed method will facilitate the development and validation of multiphase closure models of subcooled boiling flows.
December 2015
School of Engineering
Dept. of Mechanical, Aerospace, and Nuclear Engineering
Rensselaer Polytechnic Institute, Troy, NY
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