On post-dryout heat transfer in channels with flow obstacles

Abstract

This paper describes a new approach to predict post-dryout heat transfer in channels with flow obstacles. Using experimental data obtained in annular test sections at prototypical BWR conditions, the existing Saha correlation for post-dryout heat transfer has been modified to account for the presence of obstacles. The obstacle effect is taken into account in the following way: (a) the critical quality downstream of an obstacle is found; (b) an exponential function of equilibrium quality is applied to describe the decrease of heat transfer coefficient in the developing post-dryout region; (c) an additional heat transfer enhancement term is applied downstream of the obstacle. The new approach is applied to annular test sections with various flow obstacles and a significant improvement of accuracy of wall temperature prediction, as compared to reference methods, is shown.