Assessment of Post-Critical-Heat Flux Models with Lehigh Nonequilibrium Data.

摘要

The report presents comparisons of convective film boiling model predictions to the post-critical-heat flux experimental data obtained at Lehigh University. At Lehigh University, measurements of axially varying vapor superheats in dispersed flow convective film boiling have been obtained for water in a vertical tube at low pressure and mass flux conditions. These data were taken using a slow 'reflood' process allowing for measurement of wall and vapor temperature as a function of the distance from the quench front. The experimental set-up and the film boiling data are summarized in a separate report by Evans, Webb and Chen (NUREG/CR-3363). Two types of convective film boiling models have been evaluated: (1) equilibrium models, which do not allow for vapor superheating, and (2) nonequilibrium models which attempt to predict the actual quality and vapor superheats. The equilibrium correlations are restricted to local models while the nonequilibrium correlations include local and axial-history dependent models. These correlations have been compared with more than 500 data points reported in NUREG/CR-3363.