Surface coking deposition influences on flow and heat transfer of supercritical hydrocarbon fuel in helical tubes

Surface coking deposition influences on flow and heat transfer of aviation kerosene RP-3 in helical tubes were experimentally investigated at supercritical pressure. Four types of helical tubes with fixed pitch and various helical diameters have 1.86 mm inner diameter and 2.2 mm outer diameter. The system pressure, inlet temperature, mass flow rate were fixed at 5 MPa, 400 K and 1178 kg/m2 s, respectively. The results indicate that the helical centrifugal force could inhibit the thermal oxidation coking and slow down the growth rate of press drop within maximum value of 47.6%. For the same cross section, the outer heat transfer coefficient (HTC) decreases gradually and eventually is less than the inner side due to coking deposition. Finally, a correlation of Nusselt number considering coking deposition was simulated to predict the heat transfer characteristics.