Jet fuel is used as a coolant before it is burned in the combustor of the aircraft. Insoluble particles and surface deposits can impair engine performance. Jet fuel thermal oxidation test (JFTOT) defines the standard test method for evaluation of the deposit formed through heating fuels in tubes caused by thermal oxidation (<400 degrees C). At a higher temperature, fuel in the heating process decomposes leading to surface deposits by coking. In this work, we propose a method to evaluate the security of fuel flowing in the tube at high temperatures (>500 degrees C). The heat transfer and cracking performances of two hydrocarbon fuels which are laboratory modified aviation kerosene (Fuel 1 (rho = 0.85 g/cm(3)) and Fuel 2 (rho = 0.78 g/cm(3))) have been investigated in a heat exchanger under supercritical conditions (T = 700-770 degrees C, rho = 2.5-5.5 MPa, m = 0.4-1.0 g/s). The temperature and flow rate in this work are much higher than those in JFIOT. The safe run time (SAT) is used to evaluate the heat transfer security of each fuel. As the temperature increases or the flow rate decreases or the pressure increases, the SRTs of Fuel 1 and Fuel 2 decrease clearly. In general, the heat transfer security of Fuel 1 is better than that of Fuel 2. Moreover, the volumetric heat sink of Fuel 1 is larger than that of Fuel 2. So, the overall performance of Fuel 1 is more excellent when it is used as propellant and coolant for hypersonic aircraft. In consideration of the heat transfer security, heat sink and the required driving force for aircraft, the temperature of fuel at the exit of heat transfer passage should be set as 740 degrees C, the flow rate of fuel should be 0.6-1.0 g/s, the pressure of heat transfer passage should be 3.5 MPa. Based on these results, we find that the modification of a high density fuel is an effective way to prepare an advanced hydrocarbon fuel. (C) 2016 Elsevier B.V. All rights reserved.