A. C. Nixon
Published: 1965
Total Pages: 69
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Investigation of the feasibility of utilizing hydrocarbons as heat-sink fuels for hypersonic aircraft is continuing. Both thermal and catalytic endothermic reactions are being considered, at temperatures up to 1400 F, pressures to 1000 psi, liquid hourly space velocities up to 260 and 150, respectively. Mono- and dicyclic naphthenes appear to be the most promising feeds to date. Utilizing dehydrogenation to the corresponding aromatics over a platinum on alumina catalyst, heat sinks of about 1000 Btu/lb of feed should be achievable with the lower members of the series, such as cyclohexane, methylcyclohexane, dicyclohexyl and decalin. Laboratory studies of the dehydrogenation of decalin to naphthalene over a Pt/A12O3 catalyst have indicated that the occurrence of this reaction in two stages (with tetralin as the intermediate), and its existence in cis and feed showed a surprising tendency to deactivate the catalyst but present evidence is that this should be resolvable. Studies on the effect of low oxygen concentrations on thermal stability indicate that stringent control of the oxygen content of stable fuels in the sub-ppm region markedly improve thermal stability, and hence decreases heat exchanger fouling.