Study On Supercritical Pyrolysis And Dehydrogenation Of Decalin

In the hypersonic flight over 5 Mach as the available effective coolant used in hypersonic vehicles, the traditional fuels can't meet the demands at hypersonic flight just using their physical heat-absorbed capacities. To meet this challenge, endothermic fuels that chemically decompose into energetic gases via cracking reactions and provide extremely high heat sink have been developed. These fuels provide the cooling for hypersonic flight and convert the fuel into components that can be burned in a supersonic combustor.Numerous studies have been published on the endothermic fuels, which included the choice of fuels, the types of endothermic reaction, the improvement of fuels performance and test of fuels on practical aircraft. The present work is to study the endothermic reaction of fuels. The main contents were as follows: Firstly, the physical properties of fuels were calculated by using SUPERSTRAPP software (coded by NIST). The results showed that the properties of fuels in supercritical state were significantly different from that in normal pressure, this would made resident time of fuels in reactor prolonged, and would gave great effect on reaction of fuels.Secondly, the pyrolysis reaction of decalin and MCH were studied. After analyzing the compositions of two fuels pyrolytic products, the pyrolysis mechanisms of decalin and MCH were discussed, their macrokinetics equations are measured respectively.Thirdly, the heat sink values of the two fuels at different pyrolytic temperatures were calculated by using SUPERTRAPP software (coded by NIST). Pyrolysis reaction of both decalin and MCH can provide high heat sink at high rection temperature. When the temperature is 700℃, the heat sink of decalin and MCH are 2437.25kJ/kg and 3119.29kJ/kg respectively, the two fuels can offer enough cooling capacity for hypersonic flight at above 5 Mach. Finally, selectivity and catalyst lifetime of endothermic fuel decalin catalytic dehydrogenation was studied at normal pressure and supercritical state. The effects of temperature, pressure and space velocity on decalin dehydrogenation conversion were studied. The used catalyst was analyzed by TGA. The results showed that total dehydrogenation conversion of decalin enhanced significantly. Dehydrogenation of cis-decalin was more easily than that of trans-decalin. Carbon deposited on catalyst has less effect on reaction in supercritical state than normal state.