This study investigates the evaporation heat transfer coefficient and two-phase frictional pressure drop of refrigerant mixture R1234ze(E)/R32 at various R1234ze(E) composition ratios in a brazed plate heat exchanger. The heat transfer coefficient of R1234ze(E)/R32 shows a concave curve as a function of composition ratio owing to the temperature glide of the mixture, whereas the two-phase frictional pressure drop increases exponentially with respect to the composition ratio. In addition, the averaged evaporation heat transfer characteristics of R32, R1234ze(E)/R32 (85%/15%), and R1234ze(E) are compared by considering the European Union (EU) regulations for global warming potential (GWP). For regulation phase A (GWP > 750), R32 exhibits the best heat transfer performance, whereas for regulation phase B (GWP > 150), R1234ze(E) shows a favorable averaged heat transfer coefficient compared to R410A and R134a. Finally, based on the measured data, correlations for the Nusselt number and two-phase friction factor for R1234ze(E)/R32 are derived as a function of composition ratio using a nonlinear interpolation method with the pre-developed correlations for pure R1234ze(E) and R32. (C) 2019 Elsevier Ltd. All rights reserved.
1.Korea Univ, Dept Mech Engn, 145 Anam Ro, Seoul 02841, South Korea 2.Korea Inst Energy Res, Energy Network Lab, 152 Gajeong Ro, Daejeon 34129, South Korea
Recommended Citation:
Lee, DongChan,Kim, Dongwoo,Cho, Wonhee,et al. Evaporation heat transfer and pressure drop characteristics of R1234ze(E)/R32 as a function of composition ratio in a brazed plate heat exchanger[J]. INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER,2019-01-01,140:216-226