Flow pattern-based heat transfer correlation for condensing R-22 in a smooth tube

Abstract

Paper presented at the 5th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 1-4 July, 2007.This paper presents a study of probabilistic flow regime-based heat transfer coefficients during refrigerant condensation inside a smooth tube. Experimental work was conducted using refrigerant R-22, at an average saturation temperature of 40oC, with mass fluxes ranging from 250- 650 kg/m2s, and with test section inlet vapor qualities ranging from 0.65 down to 0.10. These tests conditions represent mostly Intermittent flow, with some data points in the Annular and Stratified-wavy flow regimes. Utilizing time fraction data gathered in this experimental setup, a new time fraction-corrected flow regime-based heat transfer correlation, heavily based on the Thome et al. (J.R. Thome, J. El Hajal and A. Cavallini, Condensation in horizontal tubes, part 2: New heat transfer model based on flow regimes, International Journal of Heat and Mass Transfer, 46:3365-3387, 2003) correlation was developed for use in the Intermittent flow regime. The modified correlation predicted the experimental data with a mean absolute deviation of 10%.