Experimental Investigation of Flow Coking and Coke Deposition of Supercritical Hydrocarbon Fuels in Porous Media

Transpiration cooling technology is a feasible thermal protection method for hypersonic vehicles. To ensure the safety of transpiration cooling structures, the coke deposition rule of hydrocarbon fuels in porous media is a key problem that has to be considered. In this paper, experimental studies are reported on coke deposition of n-decane and HF-II fuel in sintered bronze porous media at different pressures and a temperature ranging from 350 to 638 degrees C. Results showed that the temperature was a dominant factor for coke generation from hydrocarbon fuels. Two types of coking behaviors, i.e., thermal-oxidative coking and pyrolysis coking, were observed, which resulted in the coke surface deposition rate exhibiting a double-peak curve. At a certain temperature, the mass flow rate determined the fluid residence time in porous channels. Thermal-oxidative coking was affected by the residence time and the dissolved oxygen concentration, so the coke surface deposition rate increased at first and then decreased with the mass flow rate. However, pyrolysis coking was only affected by the residence time, and in this case, the coke surface deposition rate decreased monotonously with the mass flow rate.