Evaluation of Pure Hydrocarbons as Jet Fuels.

Abstract

AIRCRAFT traveling a t supersonic speeds require fuels with a greater heat sink capacity than that offered by petroleum fuels in current use because of the aerodynamic heating attendant with such speeds. The heat generated a t subsonic flight speeds is readily dissipated by air cooling. At supersonic speeds, however, the rate of heat dissipation is inadequate. Fuels that can absorb this extra heat without undergoing adverse chemical change offer an answer to this cooling problem. The requirements for such fuels are thermal stability, good combustion characteristics, closely defined properties, and the best low temperature properties possible, commensurate with the first three requisites. A thermally stable fuel would not decompose a t the high temperatures caused by supersonic speed and thus would not form deposits that would hamper fuel pumping and vaporizing systems. High heat of combustion means high energy release which increases flight range or payload. Close definition of properties refers to the reproducibility of properties by whatever method the fuel is produced and to careful minimization of contaminants. Impurities such as nitrogen and sulfur compounds will adversely affect the thermal stability of the fuel by causing deposit formation. Good low temperature properties, that is, low freezing point and low viscosity, are required for cold-climate, trouble-free performance in the fuel pumping system, effective atomization in fuel nozzles, and also for effective heat transfer in the cooling process. This investigation has as its over-all objective, the synthesis and evaluation of various classes of saturated hydrocarbons for potential jet fuel use. The evaluation program is concerned with the determination of properties required for such fuels. The actual selection of fuels, however, is the responsibility of the U. S. Air Force. Also, the results of this study should be of value to the petroleum refiner in refining and blending operations toward the selection of the most promising hydrocarbon types for jet fuel application. Finally, an important adjunct of this program has been the determination of basic properties of saturated hydrocarbons. The evaluation of 38 saturated hydrocarbons is presented as part of a continuing study.