On Population Balance Approach for Subcooled Boiling Flow Prediction

Abstract

The capability of using the population balance approach combined with a three-dimensional two-fluid model for predicting subcooled boiling flow is investigated. Experiments were conducted to study the local flow characteristics of subcooled boiling flow and to provide measured local two-phase flow parameters. Calculations were performed using the newly developed population balance boiling model to study the effects of various factors on numerical predication of local two-phase flow parameters in the subcooled boiling regime. Comparison of model predictions against local measurements was made for the radial distribution of the bubble Sauter diameter and void fraction covering a range of different mass and heat fluxes and inlet subcooling temperatures. Additional comparison using recent active nucleation site density models and empirical relationships to determine the local bubble diameter adopted by other researchers was also investigated. Overall, good agreement was achieved between predictions and measurements using the newly formulated population balance approach based on the modified MUSIG (multiple-size-group) model for subcooled boiling and two-fluid model.