Multidimensional modeling of two-phase flow and heat transfer

摘要

Purpose - This paper seeks to discuss a mechanistic modeling concept for local phenomena governing two- and multi-phase flows and heat transfer. Design/methodology/approach - An overview is given of selected issues concerning the formulation of multidimensional models of two-phase flow and heat transfer. A complete computational multiphase fluid dynamics (CMFD) model of two-phase flow is presented, including local constitutive models applicable to two-phase flows in heated channels. Results are shown of model testing and validation. Findings - It has been demonstrated that the overall model is capable of capturing various local flow and heat transfer phenomena in general, and the onset of temperature excursion (CHF) in low qualityrnforced-convection boiling, in particular. Research limitations/implications - Whereas the multiphase model formulation is applicable to a large class of problems, geometries and operating conditions, the closure laws and results are focused on forced-convection boiling in heated channels. Practical implications - The proposed approach can be used to predict multidimensional velocity field and phase distribution in two-phase flow devices and components used in thermal power plants, nuclear power plants and chemical processing plants. Originality/value - A complete mechanistic multidimensional model of forced-convection boiling in heated channels is given. The potential of a CMFD approach is demonstrated to perform virtual experiments that can be used in system design and optimization, and in safety analysis.