On the non-dimensional area of influence and its influence within the Rensselaer Polytechnic Institute (RPI) wall boiling model

Abstract

A computationally inexpensive method of determining the non-dimensional area of influence and the quenching correction factor as a function of wall superheat, for numerical implementation in multiphase Eulerian computational fluid dynamics simulations, is presented. Clarity is provided on the origin of the non-dimensional area of influence in the Rensselaer Polytechnic Institute (RPI) wall boiling model and its implementation to date. Thereafter, a method of approximating the non-dimensional area of influence in the RPI model is proposed based on the results of a Monte Carlo simulation aimed at mimicking the distribution of nucleation sites and their overlapping area of influence. The influence of bubble growth and overlapping areas of influence on the quenching correction factor (commonly referred to as the ”bubble waiting time coefficient”) is discussed and analytical models developed. Results indicate that the quenching correction factor increases (in the range of 1-1.8) with increased wall superheat (2-20 K). This stands in contrast with the commonly used value of one in literature. These findings are incorporated into multiphase Eulerian numerical model and the results are compared against an experimental case considering submerged cryogenic jet impingement boiling. The proposed correlations for the non-dimensional area of influence and quenching correction factor result in an improvement of the wall superheat root mean squared error from 4.992 to 1.378 K.