Evaluation of various active nucleation site density models of subcooled flow boiling in a vertical tube using OpenFOAM

Abstract

Abstract To evaluate the applicability of the active nucleation site density models in CFD simulations, the simulations of subcooled flow boiling process in a vertical tube are conducted with an open source CFD code, OpenFOAM. The effect of physical parameters on different active nucleation site density models is studied. The predictions of subcooled flow boiling under five active nucleation site density models have been compared with previous experimental data. Radial distributions of local void fraction, gas velocity and liquid velocity have been used for comparison of different models in different cases. It was found that the models show a significant influence on the prediction of void fraction, temperature distribution and the location of onset of nucleate boiling (ONB), while show little effect on the pressure distribution and bubble diameter. Comparing with other models, the simulation results of Lemmert and Chawla (LC) model are more suitable for predicting void fraction and liquid velocity for different conditions in simulations of subcooled flow boiling. The recommendations of different models for applicable scope are given by analyzing the simulation results. These works can provide reference for the selection of active nucleation site density models when analyzing subcooled flow boiling in vertical tube by CFD methodology.