Simulation on Heat Transfer Characteristics of Engineering Fuel under Supercritical Pressure

The pyrolysis and coking reactions play an important role in the fuel heat transfer within regenerative cooling channels. A numerical simulation was conducted to investigate the thermophysical properties and heat transfer characteristics of engineering fuels. A two-dimensional heated tube model was constructed to perform simulations on the heat transfer characteristics of hydrocarbon fuels. The comparison was made between engineering fuels regarding the differences in thermal cracking coking characteristics using the MC-Ⅱ model. The surrogate models for the thermophysical properties of fuels were established at 3 MPa and 4 MPa. The numerical results indicate that in comparison with HF-I, the heat transfer efficiency of HF-II is lower due to a combination of its thermophysical properties and distribution characteristics of pyrolysis products. Moreover, the high concentration of aromatic hydrocarbon in the pyrolysis products of HF-2 promotes non-catalytic coking. At 15 minutes, the maximum thickness of the wall coking layer for HF-1 is approximately 0.01 mm, while for HF-II it reaches about 0.16mm. The fuel inlet temperature significantly impacts the amount of thermal cracking coking in the condition of HF-II. At an inlet temperature of 400 K, the wall coking amount is approximately four times greater than that observed at 300 K.