Condensation heat transfer characteristics of a mixture of R1234ze (E) and R152a flowing inside a horizontal micro-fin tube

The condensation heat transfer characteristics of a new environmental refrigerant mixture R1234ze (E)/R152a (mass ratio 40:60, named NCUR01) in a horizontal micro-fin tube with an outer diameter of 9.52 mm were experimentally investigated. Experiments were conducted at saturation temperatures of 30°C, 35°C and 40°C, heat flux ranged from 3 to 8 kW·m−2, mass flux ranged from 25 to 75 kg·m−2·s−1, and vapor quality up to 1.0. Flow patterns of NCUR01 were estimated based on flow pattern maps. The effects of saturation temperature, heat flux, mass flux, and vapor quality on heat transfer coefficients and friction pressure drops were analyzed. The results demonstrate that the flow patterns of NCUR01 during condensation are predominantly stratified and stratified-wavy. The condensation heat transfer coefficients and friction pressure drops increase with mass flux and mean vapor quality, while decrease with saturation temperature. Heat flux has a positive correlation with heat transfer coefficients, but has little effect on friction pressure drops. In addition, experimental data were compared with predicted values of correlations in the literature, and the correlations with high accuracy were selected.