Prediction of thermal non-equilibrium in the post-dryout regime

Abstract Significant vapor superheating has been observed experimentally in the post-dryout regime. A method of evaluating the non-equilibrium in vapor enthalphy (due to vapor superheating) from experimentally obtained post-dryout data is presented. A correlation to predict this non-equilibrium, based on 1402 round tube data, has been obtained. This correlation, which is applicable only in the dry-wall region, has the correct asymptotic trends and may be extrapolated outside the range of data on which it is based. The correlation can be used, in conjunction with a superheated steam correlation, to predict post-dryout temperatures over a wider range of qualities, mass flows and pressures with better accuracy than previously used correlations.