Experimental study on evaporation heat transfer of CO 2/DME mixture refrigerant in a horizontal smooth tube

Abstract

In-tube evaporation heat transfer coefficient of pure dimethyl ether (DME) and CO 2/DME mixtures have been measured with water heated double tube heat exchanger under the conditions of mass flux of 100, 200, 300 kg m −2 s −1 and inlet saturation temperature of 10 °C. Test section was horizontally installed smooth tube with inner diameter of 4.2 mm. The heat transfer coefficient of mixture decreases with mixing CO 2 into DME in which the degradation was about 20% for 10%CO 2 and 48% for 25%CO 2. Existent correlations predict the heat transfer coefficients of pure DME within ±30% error. On the other hand, heat transfer coefficient of the mixture with higher concentration 25%CO 2 could not be predicted well by existent correlations, though those of 10%CO 2 could be correlated fairly well.