Post-dryout heat transfer to Freon in a vertical tube at high subcritical pressures

Abstract

Studies of the post-dryout heat transfer were made based on experimental data of the heat transfer to Freon 22 flowing upward in a vertical, round tube at nigh subcritical pressures (reduced pressures of 0.68–0.92). A conventional theoretical model failed in part to reproduce the measured wall temperature. A nondimensional parameter Kn was introduced to a model for the post-dryout regime to take account of the thermodynamic nonequilibrium between the vapor and the liquid droplets. A correlation of Kn was developed and a method using this correlation was successful in predicting the wall temperature.