Numerical Simulation of Saturated Film Boiling on a Horizontal Surface

TLDR

Linear Taylor instability theory has been limited in predicting film‑boiling heat transfer on horizontal surfaces because empirical correlations are required to define vapor‑liquid interface shapes and mass/heat transport. This study aims to clarify film‑boiling physics and predict heat‑transfer coefficients by fully simulating the evolving interface between immiscible fluid layers. The authors employ a coordinate‑transformation technique with numerical grid generation and a second‑order projection method to solve the coupled flow and temperature fields of the moving interface. Simulations show that film thickness and heat‑transfer coefficients vary spatially and temporally, that higher wall superheat thickens the vapor film and enlarges bulges, and that increased system pressure slows interface growth.

Abstract

The past efforts in applying linear Taylor instability theory to the prediction of heat transfer during film boiling on a horizontal surface have suffered from the fact that empirical correlations must be used to define the shape of vapor-liquid interfaces and to determine the transport of mass and heat across these interfaces. The objective of this study is to clarify the physics of film boiling and to predict heat transfer coefficients through complete numerical simulation of the evolving interface between superposed layers of immiscible fluids. A coordinate transformation technique supplemented by a numerical grid generation method and a second-order projection method are combined to solve for the flow and temperature fields associated with an evolving interface. From the numerical simulation, the film thickness and, in turn, the heat transfer coefficient are found to vary both spatially and temporally. The objective of this study is to clarify the physics of film boiling and to predict heat transfer coefficients through complete numerical simulation of the evolving interface between superposed layers of immiscible fluids. A coordinate transformation technique supplemented by a numerical grid generation method and a second-order projection method are combined to solve for the flow and temperature fields associated with an evolving interface. From the numerical simulation, the film thickness and, in turn, the heat transfer coefficient are found to vary both spatially and temporally. Increased wall superheat not only thickens the vapor film in the valley but also enlarges the vapor bulge. The effect of increased system pressure is to slow down the growth of the interface.