Flow boiling heat transfer performance of eco-friendly refrigerants

Abstract

An experimental investigation of the flow boiling heat transfer for eco-friendly pure refrigerant (R600a) and quasi-azeotropic mixture (R410A) has been presented. The test section is a smooth horizontal tube (7 mm ID) uniformly heated by the resistance heating effect. The flow boiling characteristics of the refrigerant fluids are evaluated varying the refrigerant mass flux within the range of 100-400 kg/m2s, the heat fluxes within the range 3.0-10.0 kW/m2; inlet temperatures to the evaporator are maintained within 5oC-9oC. In this study, the effect of vapor quality, mass flux, imposed heat flux and fluid thermo-physical properties of the heat transfer coefficient and two-phase pressure drop are examined. Moreover, an assessment of predictive methods is provided for
local heat transfer coefficients; also a comparison of flow regimes visualizations for R600a and R410A with a flow pattern map available in the literature is presented.
Key Words: flow boiling, heat transfer coefficient, pressure drop, flow pattern map, R600a, R410A.