ASSESSMENT OF FLUID-TO-FLUID MODELLING OF CRITICAL HEAT FLUX IN HORIZONTAL 37-ELEMENT BUNDLE FLOWS

摘要

Fluid-to-fluid modelling laws of critical heat flux (CHF) available in the literature were reviewed. The applicability of the fluid-to-fluid modelling laws was assessed using available data ranging from low to high mass fluxes in horizontal 37-element bundles simulating a CANDU~(~R) fuel string. Correlations consisting of dimensionless similarity groups were derived using modelling fluid data (Freon-12) to predict water CHF data in horizontal 37-element bundles with uniform and non-uniform axial-heat flux distribution (AFD). The results showed that at mass fluxes higher than approx4,000 kg/m~(2)s (water equivalent value), the vertical fluid-to-fluid modelling laws of Ahmad (1973) and Katto (1979) predict water CHF in horizontal 37-element bundles with non-uniform AFD with average errors of 1.4percent and 3.0percent and RMS errors of 5.9percent and 6.1percent, respectively. The Francois and Berthoud (2003) fluid-to-fluid modelling law predicts CHF in non-uniformly heated 37-element bundles in the horizontal orientation with an average error of 0.6percent and an RMS error of 10.4percent over the available range of 2,000 to 6,200 kg/m~(2)s.