Numerical gas-liquid stratified flow regime model on evaporation heat transfer in horizontal microfin tubes

The evaporation heat transfer model of stratified flow in helically grooved, horizontal microfin tubes was proposed. The profile of stratified liquid was determined using a theoretical model previously proposed for condensation in horizontal microfin tubes. The meniscus profile of stratified liquid in the grooves between adjacent fins was determined by a force balance between the gravity and surface tension forces. The Thin film evaporation model in the thin film region of the meniscus previously proposed by the authors was applied. Heat transfer through the stratified liquid was estimated using an empirical correlation proposed by Mori et al. The theoretical predictions of the circumferential average heat transfer coefficient were compared with available experimental data for four tubes and three refrigerants. A good agreement was obtained for the region Fr₀ < 2.5 if partial dry-out of the tube surface did not occur.