R-502 has been the primary refrigerant for low temperature commercial refrigeration applications for many years. The impending phase-out of CFCs dictates its elimination in the very near future. The identification of alternative(s) for R-502 therefore becomes a high priority. This paper addresses the factors to be evaluated in selecting the best replacement and identifies an azeotropic mixture ...

The microchannels/minichannels are being used in industry to yield compact geometry for heat transfer in a wide variety of application. The channels provide high heat transfer coefficients and the large surface area to volume ratios, has led to their use in compact condensers for air-conditioning and refrigerant systems. In order to achieve the compactness the present work attempts to develop a...

Herein, the application of Carnahan-Starling-vdW-β equation of state (EoS) for 13 refrigerant fluids was investigated. The EoS could predict the saturated liquid densities of these refrigerants over the temperature range of 100-400 K and pressures from zero up to187 MPa with the average absolute deviations of 2.66%. The accuracy of Carnahan-Starling-vdW-β EoS in liquid density prediction was al...

An analytical equation of state has been previously modified by Papari et al. for representing the volumetric properties of molecular fluids. However the performance of that EOS has not been yet well investigated for refrigerant fluids. This study extended that equation to 19 liquid refrigerants to predict their densities at isothermal and saturated states. Two temperature-independent parameter...

The present work is the successful extension of an improved equation of state (EOS) to refrigerant fluids. The objective is the prediction of isothermal and saturated liquid densities of refrigerants. Two temperature-independent parameters appearing in the modified EOS are closely related to critical point properties of refrigerant fluids. Our results showed that, the proposed EOS can predict w...

In the present study, the local characteristics of pressure drop and heat transfer are investigated experimentally for the condensation of a pure refrigerant R134a in multi-port extruded tubes of 8 channels in 1.36mm hydraulic diameter and 19 channels in 0.80mm hydraulic diameter. The experimental data of frictional pressure drop (F.P.D.) and condensation heat transfer coefficient (H.T.C.) are ...

In the present study, the condensation and evaporation heat transfer performance of a zeotropic refrigerant mixture (HFC32/HFC125/HFC134a) inside horizontal tubes with smooth, grooved or cross·grooved inner surfaces was investigated experimentally. The cross-gTOoved tube showed the highest heat transfer coefficient for both condensation and evaporation with the zeotropic mixture. Its heat trans...

Vapor refrigerant injection cycle with a flash tank has proven to be effective in improving system performance significantly at extremely low and high ambient temperatures. However, the control strategy of operating the system is still unclear. There is no open publication on the comprehensive study of the vapor injection cycle control strategy to date. This paper presents the experimental inve...