Large-scale heat transfer experiments with supercritical R134a flowing upward in a circular tube

Heat transfer experiments with supercritical Freon R134a flowing upward in a circular tube with inner diameter of 10 mm and a heating length of 2495 mm were conducted with a wide range of parameters: mass fluxes of 300–2000 kg/m²s, heat fluxes of 10–200 kW/m², bulk fluid temperature of 50–124 °C and pressures of 4.22–5.51 MPa. Effects of heat flux, mass flux, pressure and inlet temperature on heat transfer behavior are analyzed. Significant heat transfer deterioration is observed above a critical heat flux to mass flux ratio. Six representative correlations were selected and compared with the test data.