Greco, A.2014-12-032014-12-032007Greco, A 2007, A study on boiling heat transfer characteristics of refrigerant mixtures in a horizontal tube, Paper presented to the 5th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 1-4 July 2007.9781868546435http://hdl.handle.net/2263/42779Paper presented at the 5th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 1-4 July, 2007.In the present study the evaporating heat-transfer characteristics of mixtures of refrigerant fluids were analysed. This paper presents experimental heat transfer coefficients obtained during the evaporation of the zeotropic mixtures: R407C (R32-R125-R134a 23- 25-52% in weight) and R417A (R125-R134a-R600 46.6-50-3.4 % in weight) and of the near-azeotropic mixtures: R404A (R125/R143a/R134a 44/52/4 % by weight) and R410A (R32/R125 50/50 % by weight). The test section was a smooth, horizontal, stainless steel tube (6 mm I.D., 6 m length) uniformly heated by Joule effect. The heat transfer characteristics were measured at an evaporation pressure of about 4.00 bar varying the refrigerant mass flux within the range 200-1100 kg/m2s, with heat fluxes within the range 10-15 kW/m2. The experimental data are discussed in terms of the heat transfer coefficients as a function of the vapour quality. The experimental results clearly show that the heat transfer coefficients increase with increasing the refrigerant mass flux with a power coefficient varies in the range 0.57 – 0.86. In the experimental tests R410A shows the higher values of the heat transfer coefficients. In the paper are reported also the pressure drops values for the same experimental data.7 pagesPDFenUniversity of PretoriaUniversity of PretoriaHeat-transfer characteristics of mixtures of refrigerant fluidsEvaporation of the zeotropic mixturesPresentation