Investigation of Short Contact Time Reactors for Regeneratively Cooled Hypersonic Vehicles

Abstract

For hydrocarbon-based fuels to be viable as scramjet fuels they must be able to absorb heat from engine structures in the form of sensible, latent, and chemical enthalpies, while attempting to minimize coke formation. In this study, a short contact time catalytic reactor was used to achieve these ends. Experiments were performed using a series of different catalysts (Pt Al 2 O 3 , Rh Al 2 O 3 , and zeolite) on a set of logistical fuels (JP-7, JP-8, JP-10, and S-8, a synthetic hydrocarbon fuel currently being investigated by the U.S. Air Force). Experiments were performed at low (1-3 atmospheres) and elevated (40-50 atmospheres) pressures, at temperatures of 650 and 750 C. The production of gas-and liquid-phase species was measured as a function of pressure, temperature, residence time, and catalyst formulation. Results show the production of small (H 2 , C 1 C 3 ) species in the gas phase, with a shift from hydrogen and ethylene formation at low pressures toward methane and ethane formation at elevated pressures. In addition, significant coke formation at elevated pressures for all of the fuels was witnessed. Detailed kinetic modeling identified shortcomings in models used for describing the pyrolysis of these fuels.Presented at the 46th AIAA/ASME/SAE/ASEE Joint Propulsion

Experimental and modeling study of thermal and catalytic cracking of n-decane

“…Castaldi et al [20] studied the cracking of JP-8 and JP-10 fuels over Pt/α -Al 2 O 3 in a short contact-time reactor and found that the fuels can feasibly be converted to the desirable ethylene and hydrogen. Leylegian et al [21,22] also used the short contact time reactor to investigate the cracking of logistical fuels (JP-7, JP-8, JP-10 and S-8) over a series of different catalysts (Pt/Al 2 O 3 , Rh/Al 2 O 3 and zeolites) at pressures of 1~3atm and 40~50atm, temperatures of 650 and 750 o C. They concluded that the gaseous products shifted from hydrogen and ethylene formation at low pressures towards methane and ethane formation at high pressures. Brogan et al [23] studied thermal and catalytic cracking of butane over Pt/Al 2 O 3 and the product distribution identified by Raman spectroscopy showed that the catalytic cracking of butane yielded more methane and ethylene than those from thermal cracking.…”

“…Noble metals, such as Platinum (Pt), Palladium (Pd), and Rhodium (Rh) are used as catalysts in many heterogeneous catalytic reactions for its excellent activity, selectivity and stability [14]. Platinum, supported on Al 2 O 3 or SiO 2 , is one of the most valuable catalysts because of catalyzing a wide variety of hydrocarbon conversion reactions involving C-C and C-H bond activation and has been widely used in the catalytic cracking and reforming processes in industrial research [15][16][17][18][19][20][21][22].…”

Research on Panel Flutter Considering the Effect of Convective Active Cooling

“…During hypersonic flight, the outer surface wall structure of the vehicle is subjected to a rather harsh aerodynamic thermal environment, which seriously affects the performance and flight safety of the vehicle [16]. The convection cooling system is one of the most commonly used thermal protection strategies [17][18][19][20]. For instance, Castaldi [18] presented an effective endothermic fuel platform for regeneratively cooled hypersonic vehicles.…”

Development of a detailed pyrolysis mechanism for C1–C4 hydrocarbons under a wide range of temperature and pressure

“…Endothermic hydrocarbon fuels with high density and heat sink capacity due to endothermic reactions of the fuels, such as JP‐7, JP‐8, JP‐10, and RP‐3, have attracted much attention from researchers owing to its application as the primary coolant in thermal management of advanced aeroengines 1‐3 . During active cooling of vehicles, hydrocarbon fuels undergo thermal cracking, and the ratio of alkenes to alkanes in the cracking products largely controls the heat sink capacity of the fuel 4‐6 . To accurately determine the product distribution during hydrocarbon fuel decomposition, it is necessary to construct a detailed pyrolysis mechanism.…”