| With the development of new-generated advanced aircrafts in recent years,the hydrocarbon fuel should satisfy some technical requirements.Particularly,for a volume-limited aircraft,the high volumetric heat is the most key property.Volumetric heat is usually positively correlated with density,so the high-volume-heat hydrocarbon fuels are always called the high-density hydrocarbon fuels(HDHFs).It is generally accepted that it is an effective way to gain HDHFs by synthesizing liquid hydrocarbon fuels.Among the synthesized hydrocarbon fuels,THTCPD has attracted much attention because of its remarkable properties of density and volumetric heat.Thermal decomposition of THTCPD was investigated in this study,which will provide some reference for the application of THTCPD.It was first conducted in a batch reactor at 385-425 oC to investigate the kinetics and decomposition products of thermal decomposition of THTCPD.According to the time-dependent conversion of THTCPD at different temperatures,the activation energy and pre-exponential coefficient of the reactions were established of 248.51 kJ·mol-1 and 1.48×1015 s-1.The detailed analysis of the decomposition products indicated that THTCPD was firstly cracked into ethylene,C5(1,3-cyclopentadiene,cyclopentene and cyclopentane),benzene and C10(exo-TCD and its isomers),and then to form small molecules(methane,ethane and propane,methyl-& ethylcyclopentane,etc.).The possible primary mechanism was speculated,including β-scission,isomerization and intermolecular hydrogen abstraction reactions.Thermal decomposition of THTCPD was carried out at high pressure(4 MPa)and temperatures(550-660 oC)with different flow rates of 30-60 g/min.Ethylene and propene are the most abuandant gaseous products.In the liquid products,cyclopentene was the most,and both the yield of cycloalkane and aromatics were large.The chemical heat was remarkable after 600 oC.The results indicated that flow rate has an effective effect on conversion,the gas and liquid prouct distributions and heat,which decreased with the increasing flow rate.Finally,thermal decomposition of THTCPD and exo-TCD mixtures(THTCPD/exo-TCD)was conducted at high pressure(4 MPa).The results showed that the overall conversion and gas yield of 70%THTCPD/30%exo-TCDwere near to those of THTCPD while thoese of 50%THTCPD/50%exo-TCD were obvious larger,which increased significantly with temperature.The major products were the same with those of thermal decomposition of THTCPD.After adding exo-TCD into THTCPD seemed to have no influence on the yield of aromatics.However,the ratio of alkene/alkane in gaseous products increased with the exo-TCD added.Exo-TCD in THTCPD/exo-TCD started to decompose,mainly into its dehydrogenation products,3-cyclopentylcyclopentene and C5 at 600 oC.The liquid produts of thermal decomposition of THTCPD/exo-TCD was affected by the overall conversion,gas yield and the situation of exo-TCD decomposition.Adding exo-TCD into THTCPD can enhance the physical heat sink of the fuel,however,whenexo-TCD started to decompose,there seems no influence on the heat sink. |
