This paper presents a comparative study of fluid flow pressure drop characteristics of new alternatives for R-502, such as R-404a, R-408a, and R-507 as well as a quaternary mixture (R-32/R-125/R-134a/R-143a). The data on pressure drop characteristics were obtained inside enhanced surface tubing using an experimental setup composed of a heat pump with 8 kW capacity under steady-state conditions. Correlations based on Lockhart-Martinelli parameters have been developed and presented in dimensionless form to predict the pressure drop characteristics of the binary, ternary, and quaternary refrigerant mixtures. The condensation data showed that the use of such alternatives as R-507 and R-404a would require compressors with larger volumetric capacities than for R-502.

Units: SI