Heat transfer characteristics and correlation for CO2/propane mixtures flow evaporation in a smooth mini tube

Abstract

The flow evaporation heat transfer characteristics of CO2 and propane mixtures in a horizontal smooth 2 mm inner diameter tube were experimentally investigated. The working conditions included CO2 and propane composition ratios of 100:0, 75:25, 50:50, 25:75 and 0:100, initial evaporation temperature of 0–10 °C, mass flux and heat flux up to 400 kg m−2 s−1 and 15 kW m−2, respectively. The results show that the mixture heat transfer coefficient is between that of pure CO2 and pure propane for the same conditions, and increases with increasing CO2 proportion and initial evaporation temperature. The dryout vapor quality increases with increasing propane proportion or decreasing initial evaporation temperature. A correlation to predict the heat transfer coefficient for pure CO2, pure propane and various mixtures flow evaporation in small diameter tubes with the predictions agreeing well with the experimental data of this and other studies was developed.