Mechanism analysis of convective heat transfer of supercritical CO2 in heated vertical-flow tube

Abstract

Supercritical carbon dioxide is a promising working fluid for power generation due to its superior heat transfer properties. To investigate its heat transfer behavior under in a vertical tube under operating conditions, an combined experimental and numerical study was conducted. Parameters range from (15−27) MPa of pressure, (763–2774) kg/(m²s) of mass flux, (207−424) kW/m² of heat flux. Results show that pressure and mass flux effects on heat transfer coefficients are consistent under uniform heating conditions. However, under high heat flux conditions, the non-uniform distribution of fluid density along the flow direction reduces turbulence production, leading to a lower heat transfer coefficient. Moreover, a new heat transfer correlation was proposed. The predictive and experimental values demonstrated a high correlation, with 79.30 % of data points falling within a 10 % error range and 100 % within a 20 % error range.