Pressure effect on the heat transfer characteristics of hydrocarbon fuel in the horizontal circular tube at supercritical pressures

Experiments were performed to investigate the pressure effect on the heat transfer characteristic of hydrocarbon fuel RP-3 in the horizontal circular tube at supercritical pressures. The mechanisms of heat transfer variation due to the radial thermal property, buoyancy and acceleration effects were discussed as well. The results showed that the heat transfer coefficient increased with the rising fuel bulk temperature. Under different pressures, the fuel thermal property variation's gradient led to the discrepancies of heat transfer and Nu_x peak points at the same dimensionless bulk temperature. The main reason of the heat transfer distribution was attributable to the radial thermal property gradient due to the temperature discrepancy between the tube inner wall and bulk fuel. However, the buoyancy and acceleration effect were limited in the experiment region. It showed that the dimensionless parameter Gr_q/Gr_th precisely reflected the heat transfer characteristic variation of the supercritical hydrocarbon in the horizontal circular tube.