Evaluation of Interfacial Heat Transfer Models for Flashing Flow with Two-Fluid CFD

Abstract

Abstract:The complexity of flashing flows is increased vastly by the interphase heat transfer as well as its coupling with mass and momentum transfers. A reliable heat transfer coefficient is the key in the modelling of such kinds of flows with the two-fluid model. An extensive literature survey on computational modelling of flashing flows has been given in previous work. The present work is aimed at giving a brief review on available theories and correlations for the estimation of interphase heat transfer coefficient, and evaluating them quantitatively based on computational fluid dynamics simulations of bubble growth in superheated liquid. The comparison of predictions for bubble growth rate obtained by using different correlations with the experimental as well as direct numerical simulation data reveals that the performance of the correlations is dependent on the Jakob number and Reynolds number. No generally applicable correlations are available. Both conduction and convection are important in cases of bubble rising and translating in stagnant liquid at high Jakob numbers. The correlations combining the analytical solution for heat diffusion and the theoretical relation for potential flow give the best agreement.

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“…Particle displacement in our simulations is mainly caused by wind from an opened window, or from the inlets and outlets of the HVAC ventilation system. The heat transfer model of Ranz and Marshall ( Aissa et al, 2015 , Liao and Lucas, 2018 ) was used and for particle interaction the stochastic collision model of O’Rourke was adopted ( O’rourke, 1980 ).…”

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“…There have been a large body of work on interfacial heat transfer analyses. Numerous analytical and empirical correlations for the calculation of interphase heat transfer coefficient are available 65 . Some of them are listed in Table 1.…”

“…Numerous analytical and empirical correlations for the calculation of interphase heat transfer coefficient are available. 65 Some of them are listed in Table 1. They correlated the Nusselt number further with other dimensionless numbers characterizing the hydrodynamic and thermodynamic conditions like the Jakob number Ja, Reynolds number Re g,j , and Péclet number Pe g,j .…”

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