Investigation on Sub-models of Population Balance Model for Subcooled Boiling in Vertical Gas-liquid Flow by Comprehensive Evaluation

Abstract

This paper presents a comprehensive evaluation on the sub-models for solving the population balance model (PBM) under subcooled boiling condition in a vertical gas-liquid flow. Firstly, bubble mechanisms occurring in the vertical gas-liquid flow under subcooled boiling are systematically reviewed. Then, comprehensive evaluations on the sub-models including bubble nucleation, condensation, coalescence, and breakup are elaborated in case of the high temperature and pressure application. In addition, the calculating results of different sub-models of the PBM are analyzed for the vertical gas-liquid flow with full working conditions. The results indicate that the detailed evaluation on the PBMs and appropriate models are especially vital for a practical engineering application. Six sub-models, which are related to the magnitude of bubble departure diameter Dl, the dependency of inter-phase heat transfer coefficient h, the analysis of interface area concentration ai, comparison of coalescence rate a(di, dj), tendency of the breakup rate Ω(dp, dd) and dimensionless daughter size distribution β(fbv, 1), are analyzed to evaluate their accuracy and the application situation. These results are helpful to identify the best performing model and provide valid recommendations for solving PBM.