Experimental Investigation of Heat Transfer During Vertical Upward Flow of Supercritical CO2in Circular Tube

An experimental investigation of turbulent heat transfer during the vertical upward flow of supercritical CO2 was conducted in a circular tube with inner diameter of 4.5 mm. The experiments were conducted at bulk fluid temperatures ranging from 29 to 115 °C, pressures from 74.6 to 102.6 bar, local wall heat fluxes from 38 to 234 kW/m2, and mass fluxes from 208 to 874 kg/m2s. At moderate wall heat and low mass fluxes, the wall temperature had a noticeable peak value. For observing the buoyancy and flow acceleration effects on heat transfer, the ratios of Nusselt numbers from the experimental data and a reference correlation were compared with the Bo* and q distributions. The flow acceleration parameter q appropriately represented the heat transfer phenomena in the experiments. A new heat transfer correlation for the vertical upward flow of the supercritical pressure fluid was developed, and was found to agree with the experimental data with an error margin of ±30 %. † Corresponding Author,dekim@knu.ac.kr C 2014 The Korean Society of Mechanical Engineers