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International Heat Transfer Conference 15

ISSN: 2377-424X (online)
ISSN: 2377-4371 (flashdrive)

In-tube Condensation of Low GWP Mixture Refrigerants R1234ze(E)/R32

Akio Miyara
Saga University, Honjo-machi, Saga-shi, Saga 840 – 0052, Japan; International Institute for Carbon – Neutral Energy Research, Kuyshu University, Fukuoka-shi, Japan

Hasan M.M. Afroz
Department of Mechanical Engineering

Md. Anowar Hossain
Department of Mechanical Engineering

DOI: 10.1615/IHTC15.cds.009602
pages 737-750


KEY WORDS: Condensation, Heat exchanger, Mixture refrigerants, Low GWP, Heat transfer degradation, Mass transfer resistance

Abstract

In the race of searching next generation refrigerants, hydro?uoroole?ns (HFOs) such as R1234yf and R1234ze(E) have already gotten priority because of their low global warming potential (GWP). R1234yf has already been proven as alternative of R134a for mobile air conditioners. Application of R1234ze(E) in turbo refrigerator is being tested. They would be the closest to extend to practical implementation. In order to extend the application fields mixtures of refrigerants is desired because thermodynamic properties of pure refrigerants are limited. R1234ze(E)/R32 mixtures are expected as the next generation refrigerant in the field of air-conditioning for domestic and business uses. However, there is still no sufficient data for condensation heat transfer coefficient and pressure drop which are required for the design of heat exchanger and the simulation of the new refrigerant. In this study, we have investigated the effect of mass concentration of R32 on R1234ze(E)/R32 mixtures and also compared with near azeotropic mixture R410A for condensation heat transfer coefficient. Experiments were carried out for R1234ze(E), R32, R410A and zeotropic mixtures of R1234ze(E) and R32 with mass fractions of 0.55/0.45 and 0.70/0.30. Experiments were done under the conditions of mass fluxes of 49-445 kg/(m2 s) and saturation temperatures of 35-45 C. The condensation heat transfer coefficient of R1234ze(E)/R32 with mass fraction of 0.55/0.45 is comparable with R410A. Experimental results were compared with some conventional correlations. In addition, a mathematical model combining the correlations of heat transfer and mass transfer at both the vapor and liquid side is used to obtain the interface temperature and interface concentration. The effects of quality, mass flux, mixture concentration and temperature glide on the heat transfer degradation have been clearly analyzed.

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