Heat transfer to freon near the critical pressure flowing in tubes. 3rd report Post-dryout heat transfer.

Abstract

Studies of the post-dryout heat transfer were made based on the experimental data of the heat transfer to Freon 22 flowing upword in vertical, uniformly heated round tubes ( 9and 13 mm ID) for a range of reduced pressure of 0.68 to 0.92, mass velocity of 400 to 1600 kg/(m2·s) and heat flux of 12 to 70 kW/m2. The wall temperatures estimated by the use of a conventional, theoretical model agreed qualitatively with those measured, but not quantitatively. 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 obtained, and this correlation, used with the correlation for the heat transfer to the superheated vapor, was successful in predicting