Binary or ternary blends of hydroflourocarbons (HFCs) and hydrofluoroolefins (HFOs) are recently emerging as possible substitutes for the high GWP (Global Warming Potential) fluids currently employed in refrigeration and air-conditioning industry. In the present paper, heat transfer coefficients of a ternary mixture of R1234yf, R32 and CO2, ASHRAE designation R455A, 75.5/21.5/3.0 by mass composition, have been measured during condensation inside a minichannel having a 0.96 mm internal diameter and in a conventional tube with 8.0 mm diameter. Tests have been performed at 40°C mean saturation temperature. The present experimental database is used to assess available predicting correlations for condensation of mixtures, providing information on the applicability of available models.
Papers presented at the 13th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Portoroz, Slovenia on 17-19 July 2017 .