Flow boiling heat transfer, pressure drop and dryout characteristics of R1234yf: Experimental results and predictions

•Boiling heat transfer, pressure drop and dry-out characteristics of R1234yf in a vertical mini-channel.•Significant effect of heat flux on heat transfer performance.•Heat transfer performance slightly increased with increasing operating pressure.•Heat transfer coefficients remained unaffected with varying mass flux and vapor quality.•Frictional pressure drop increased with mass flux and with increase in vapor quality.•Dryout heat flux remained unaffected with varying saturation temperature.

Flow boiling heat transfer, pressure drop and dryout characteristics of R1234yf in a vertical stainless steel test section (1.60 mm inside diameter and 245 mm heated length) under upward flow conditions are reported in this article. The experiments were carried out at 27 and 32 °C saturation temperatures with five mass fluxes in the range of 100–500 kg/m2 s while the applied heat flux was in the range of 5–130 kW/m2. The experiments were carried out with gradual increase of the applied heat flux til completion of dryout. Under similar conditions, tests were repeated with R134a in the same test setup to compare thermal performance of these two refrigerants. The results showed that boiling heat transfer was strongly controlled by the applied heat flux and operating pressure with insignificant dependence on mass flux and vapor quality. The frictional pressure drop increased with mass flux and vapor quality and decreased with increasing saturation temperature as expected. Signs of dryout first appeared at vapor qualities of 85%, with the values generally increasing with increasing mass flux. The effect of varying system pressure was insignificant. The experimental results (boiling heat transfer, pressure drop and dryout heat flux) were compared with the predictions from well-known correlations (for macro and micro-scale channels) from the literature.