Thermal and Hydraulic Characteristics of SCO2 in a Horizontal Tube at High Reynolds Number
- Additional Document Info
- View All
Increasing thermal efficiency of power plants is an important step to reduce cost of produced electricity, an essential goal in achieving long-term stable economic growth. Working fluids at supercritical state (especially water, carbon dioxide, and helium) have been considered as the heat transfer media for Brayton cycle to reach this goal for decades. There is no phase change in supercritical cycles, as the cycle operates above the critical pressure of the working fluid, which results in reduction of the power plant size and cost due to elimination of condenser. It is well known that small variations in the fluid temperature and pressure near critical point, pseudo-critical region, can lead to significant change in the thermo-physical properties of the fluid. Acceptable analytical and numerical models for thermal and hydraulic resistance of these fluids in pipes are still being developed especially in turbulent flow and at high heat fluxes where property variation is significant. Therefore, further experimental investigations are required to better understand the thermal and hydraulic behavior of these fluids before it could be widely used in industrial applications. Heat transfer and pressure drop measurements for pseudo-critical CO2 flow in a horizontal pipe is reported here at high Reynolds number (2×104 < Re < 105). Heat transfer measurements were carried out at several mass flow rates, inlet fluid temperatures, system pressures, and wall heat fluxes. Semi-local heat transfer coefficients are obtained to investigate the influence of these parameters on the forced convection heat transfer in the tube. The obtained heat transfer data is analyzed and compared with existing empirical correlations. Total pressure drop measurements were also conducted in some selected conditions. The effect of thermo-physical properties variations and heat fluxes in total pressure drop is analyzed by comparing the obtained data with existing correlations.
author list (cited authors)
Tanimizu, K., Sadr, R., & Ranjan, D.