The two-phase heat transfer coefficient and pressure drop characteristics of refrigerant R22 and R407C (a mixture of R32/R125/R134a, 23%/25%/52%) in a micro-fin tube with nominal diameter 9.52 mm were presented in this study. Experimental data were taken at an evaporation pressure of 600 kPa. The mass flux was between 100 and 300 kg/m2-s and the heat fluxes were between 6 and 14 kW/m2. Experimental data were presented in the form of length-averaged heat transfer coefficients and frictional pressure gradients. The effect of heat flux and mass flux on the heat transfer coefficients were also reported in the present investigation. It is found that the heat transfer coefficients for R407C are considerably lower than R22 (50-80% less), and the pressure drop of R407C is 30-50% lower as compared to R22.
- Heat transfer coefficients