Endothermic fuel

Keywords thermal and catalytic cracking, endothermic fuel, supercritical conditions... 

Zeppieri, S., High Temperature Experimental and Computational Studies of the Pyrolysis and Oxidation of Endothermic Fuels, Ph.D. Thesis, Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ, 1999. 

Zhou, N., and A. Krishnan. 1996. A numerical model for endothermic fuel flows with heterogeneous catalysis. AIAA Paper No. 96-0650. 

Koecker (Ref 17) reviews specification requirements of fuels for industrial gas turbines, conventional jet turbines (kerosine gas oils), supersonic jet engines (JP-5 JP-6), and future hypersonic jets (endothermic fuels)... 

Heat output can also be boosted by the use of endothermic fuels, i.e. those that decompose into the elements with release of energy. Two of these are cyanogen [(CNjg] and carbon subnitride (QNj),... 

The patent filed in 1991 by the United States Air Force (Anon, 1991) comes close to the concept which allowed the subject of this study to germinate. The USAF proposed a hollow gas turbine rotor blade with a catalyst coated on the inner surface. The cooling would be effected by vaporisation and decomposition of an endothermic fuel introduced into the hollow blade. The concept is illustrated in Figure 8.13. The endothermic fuel is defined as one which is liquid and which decomposes in the presence of a catalyst into two or more gaseous compounds different chemically from the liquid. At least one of the gaseous compounds is, of course, combustible in this case. The liquid fuels covered in the patent include methylcyclohexane, methanol, n-heptane or JP7 (kerosene fuel). An additional feature of using a liquid fuel as the feedstock is that latent heat of vaporisation contributes to cooUng, in addition to the endothermic reaction. 

Anon, (1991). US Patent 5125793. Turbine blade cooling with endothermic fuel. Assigned to the USA as represented by the Secretary of the Air Force, filed 8 July. 

Composite fuels (hydrogen + hydrocarbon mixtures) used for propulsion systems bring additional questions. Such fuels are formed by mixing H2 with hydrocarbons at high temperatures (endothermic fuels) resulting in heavy hydrocarbon hydrogenation [2-5]. The advantages of combustible H2-hydrocarbon composite mixtures are well known and have been discussed scores of times [6]. 

R.D. Hawtom, A.C. Nixon, Shock tube ignition delay studies of endothermic fuels. AIAA J 4(3), 513-520 (1966)... 

L.S. Yanovski, Endothermic fuels for hypersonic aviation, in Proceedings ofAGARD conference on fuels and combustion technology for advanced aircraft engines, 1993. AGARD CP-536, pp. 44.1-44.8... 

HH mixtures have become of greater interest since endothermic fuels (EF) for jet engines were developed [43, 46, 47]. The paradoxical term endothermic fuels relates to a desire to increase a fuel cooling capability due to the dehydrogenation or thermal decomposition of heavy hydrocarbons entering into the fuel composition. 

L.S. Yanovski, V.A. Sosunov, Y.M. Shikman, The application of endothermic fuels for high speed propulsion systems, in Proceedings of the 13-th Symposium (Int.) on Air-Breathing Engines, vol. 1 (AIAA, New York, 1997), pp. 59-69, AIAA... 

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