Fluid-to-Fluid Modelling of Critical Heat Flux in 37-Element Bundles

Abstract

The applicability of fluid-to-fluid modelling for critical heat flux (CHF) in 37-element bundles has been examined. CHF data obtained with 37-element bundle simulators from various Freon test programs at Chalk River Laboratories (CRL) were compared against those obtained from the water-test programs1. Thecomparison was based on a transformation of the Freon parameters (i.e., pressure, mass flux and CHF) into water-equivalent values (no transformation is needed for dryout quality, which represents the nondimensional value of enthalpy). In addition, this study examined the impact of axial heat-flux distributionand channel orientation on fluid-to-fluid modelling. At high-pressure and high-flow conditions of interest, the water-equivalent values of the Freon-test data closely represent the water-test data of uniformly and non-uniformly heated bundle strings for vertical and horizontal flows. The effects of axial heat-fluxdistribution and channel orientation on bundle CHF have also been closely simulated with Freon at conditions of interest.