Heat Transfer Characteristics of Aviation Kerosene Flowing in Enhanced Tubes at Supercritical Pressure

Results of an experimental investigation on heat transfer characteristics of kerosene flowing in vertical upward high-flux tubes at supercritical pressures are presented. Three metal powder-coated tubes (high-flux tubes) and one smooth tube have been tested and compared. The three high-flux tubes all perform much better than the smooth tube at the same parameters of the tube and same working conditions. The observed enhancement in heat transfer is mainly due to the disturbance introduced in the low field by the metal powder coatings and the differences in the thermophysical properties. The heat transfer coefficient in the metal-coated tube (200 mesh) has been found to be 2.5 times that in the smooth tube. Yet, it has been found that both too large and too small of a particle diameter of the metal powder coating on the tube surface could cause the heat transfer to deteriorate. The high-flux tube with a particle diameter of 200 mesh was found to exhibit the best cooling performance. The pressure drop was observed to increase with the increase of the particle diameter. However, the pressure drop was found to be three orders of magnitude smaller than the working pressure in the test section, thus the pressure drop for all practical purposes may be neglected. The density, viscosity, and thermal conductivity of kerosene at different temperatures and supercritical pressures were evaluated using the extended corresponding state principle, which has been proven to show good consistency with the experimental results.