Effects of n-decane pyrolytic products on heat transfer in regenerative channels under supercritical pressure

Abstract

The study of the heat transfer process in the regenerative cooling channel of the scramjet engine is always one of the main focuses on highlighting the heat transfer characteristics caused by the pyrolysis of n-decane under supercritical pressure. The heat transfer is simulated in detail using the standard k-ε two-equation turbulent model and pseudo-detailed chemical kinetics mechanism. The results indicate that the dramatic changes in density and dynamic viscosity could lead to heat transfer deterioration at the beginning of the heated channel. The change rate of density and dynamic viscosity can reach up to 75 % and 97.4 %, separately. At the same time, the physical heat sink takes the lead because of the changes in the mixture's specific heat capacity near the pseudo-critical region which are mainly contributed by C5 (pentane and pentene), and the proportion in total heat sink can reach up to 17.4 % when the conversion is below 15.0 %. The advantage of the endothermic cracking reaction is not reflected in the heat transfer process when the conversion of the fuel is lower than 25.0 % in this work. For practical applications, the effects of the pyrolytic products’ types and properties on the pyrolytic mechanism and heat sink should be performed to maximize the cooling capacity of n-decane in the cooling channel.