Two Phase Flow Split Model for Parallel Channels

Abstract

A model has been developed for the determination of two phase flow distributions between multiple parallel channels which communicate between a common upper and a common lower plenum. It utilizes the requirement of equal plenum to plenum pressure drops through the channels, continuity equations at the lower plenum channel intake boundaries, together with phase-split relationships at the channel inlets, to set up a series of nonlinear simultaneous equations. The equations are solved using the Broyden’smethod [4], a modification of the Newton’s method. The model and code are capable of handling single and two phase flows, steady states and transients, up to ten parallel flow paths, simple and complicated geometries, including the boilers of fossil steam generators and nuclear power plants. A test calculation has been made with a simplified three-channel system subjected to a two-phase flow transient, and the results have been very encouraging.