Prediction of dryout and post-dryout heat transfer using a two-phase CFD model

Abstract

This study focuses on development of an integrated CFD model for diabatic high quality two-phase flow including tarns-dryout regions from annular-mist regime to mist regime. One unified three-field CFD model accounting for droplets, gas, and liquid film was developed to simulate both pre and post dryout regions, with local models to determine the dryout occurrence. The thin liquid film model was coupled to the gas core flow model, which is described using the Eulerian–Eulerian approach. For the post-dryout region, the various heat and mass transfer mechanisms between the wall, the gas phase, and the droplets were identified, including the wall-gas convective heat transfer, the droplet evaporation, the droplet-wall direct contact heat transfer and the thermal radiation, to calculate the temperature of the wall and the fluid. Of the most interests, dryout location and wall temperature measurements from a post-dryout heat transfer experiment have been used for the validation. Simulation results show that the dramatic temperature excursion could be well captured using current models. Nevertheless, more work will be continued to improve the accuracy of the results.