Numerical Simulation of Bubble Merger Process on a Single Nucleation Site During Pool Nucleate Boiling

Abstract

A bubble merger process on a single nucleation site has been investigated by numerically solving the equations governing conservation of mass, momentum and energy in the vapor and liquid phases. The vapor-liquid interface is captured by a level set method which can easily handle breaking and merging of the interface. The level set method is modified to include the effects of phase change at the interface and contact angle at the wall. Also, the evaporative heat flux from the thin liquid film that forms underneath a growing bubble attached to the wall is incorporated in the analysis. Based on the numerical simulations, the effect of bubble merger on vapor removal rate, flow field and heat transfer has been quantified. The bubble merger pattern predicted numerically has been found to compare well with the experimental observations.

Recent Advances in Vapor Chamber Transport Characterization for High-Heat-Flux Applications

“…The vapor columns only broke apart once liquid flow to the surface was insufficient to maintain new vapor mass flux to support the columns [171]. The potential for complete numerical modeling of boiling heat transfer is supported by good agreement with data obtained from surfaces with single or multiple controlled nucleation sites [163,172]; however, further computational advancements are required to predict nucleate boiling in complex three-dimensional geometries, particularly at high heat fluxes when vapor-liquid interfaces evolve rapidly. To obtain reasonable comparison against experimental vapor chamber performance data for conditions that result in boiling in the wick structure, Ranjan et al [173] adopted a semi-empirical approach to model boiling conditions at high heat flux inputs.…”

“…As discussed by Dhir [161],measurement difficulties, prediction inaccuracies, and lack of generality associated with the effort to correlate nucleate boiling mechanisms over the last half of the twentieth century, viz. nucleation site density, bubble departure diameter, and bubble departure frequency, has spurred recent investigation of direct simulation of vapor bubble growth during nucleate boiling from flat surfaces [162][163][164][165][166][167][168][169]. Reports of similar approaches in the presence of porous structures are limited.…”

Influence of heater thermal capacity on bubble dynamics and heat transfer in nucleate pool boiling

“…The numerical results of the present numerical method have been compared both with the experimental results of Siegel & Keshock [30] and with the numerical results of Son [9] and Son et al [10]. Good agreements were evident.…”

“…Simultaneously, some little liquid drops may be carried into the bubble by large interfacial deformation at the bottom of merged bubble. Son et al [10] also reported some numerical and experimental results of vertical merger on a single nucleation site. Despite of different operating conditions, similar topological evolutions are evident between the present results and those reported by Son et al [10].…”

Numerical Simulation of Single Bubble Pool Boiling in Different Gravity Conditions

“…Up to now, numerical simulations for directly analyzing the bubble dynamics and heat transfer in single bubble nucleate boiling have been performed by several investigators [1][2][3][4][5][6][7][8], most of them are focus on the normal gravity level. The aim of the present study is to simulate the single bubble boiling phenomena under variable gravity condition, wall superheat, contact angle etc.…”