The Experimental And Kinetic Modeling Study Of Cyclic Hydrocarbon Fuel HD-01 Pyrolysis Covering The Range From Low Pressure To Supercritical Condition

HD-01(major component: exo-tricyclo[5.2.1.02,6]decane,abbreviated as exo-TCD)is a kind of cyclic endothermic hydrocarbon fuel with the unique characteristics and often used as one of ideal candidate fuels for the fuel-cooled thermal management system.It is crucial to elucidate detailed pyrolysis mechanism of HD-01 for the design of thermal management system and corresponding combustors.The low-pressure pyrolysis experimental study of HD-01 was conducted for investigating the initial reaction mechanism of HD-01.The identification of products or intermediates and the isomeric distinction were accomplished by synchrotron vacuum ultraviolet photoionization mass spectrometry(SVUV-PIMS).Meanwhile,the initial unimolecular decomposition pathway of exo-TCD was calculated using transition states theory and Rice–Ramsperger–Kassel–Marcus(RRKM)theory.A detailed kinetic model of HD-01 pyrolysis was developed based on diradical decomposition theory including 316 species and 807 reactions.The modeling mole fraction of products generally agrees well with the experimental data.The competing mechanism of initial pathway of HD-01 pyrolysis was elucidated by rate-of-production analysis and sensitivity analysis.The experiments of HD-01 atmospheric pyrolysis were conducted for expanding the scope of application of HD-01 low-pressure pyrolysis model.Atmospheric experiments identified 72 species including some particular atmospheric intermediates and several PAH(Polycyclic Aromatic Hydrocarbon)products.The emergence of these species from atmospheric pyrolysis suggested that its formation mechanism may be pressure dependent.Based on the main decomposition pathway of low-pressure pyrolysis model,an atmospheric pyrolysis model was constructed including 436 species and 1260 reactions,which could relatively well predict product distribution of HD-01 atmospheric pyrolysis.It found that PAH formation from HD-01 atmospheric pyrolysis was mainly formed from synergy of multiple mechanisms through the analysis of modeling results and rate-of-production analysis.Furthermore,model validation was conducted by simulating some published experimental data using atmospheric model.The comparison of the modeling results of HD-01 pyrolysis using atmospheric model and the published model indicated that atmospheric model was more reasonable.The experimental study of HD-01 pyrolysis at high pressure was conducted to extend the applicability scope of atmospheric model to high pressure range or even to supercritical conditions.High-pressure experiments identified 88 species including some particular high-pressure products,which showed the higher pressure dependent of some H transfer reaction in high-pressure pyrolysis system.A preliminary detailed kinetic model for HD-01 high-pressure pyrolysis was constructed based on the atmospheric model including 766 species and 6436 reactions.The present high-pressure model was constructed with several mechanism adjusted similarly employing the approach in some published kinetic model mechanism,which could relatively well predict the product distribution of HD-01 pyrolysis at high pressure or even supercritical range.The reduction of HD-01 pyrolysis model was accomplished by species elimination using directed relation graph(DRG)method and additional consideration of main reaction network and sensitivity analysis.The reduced low-pressure model,atmospheric model and high-pressure model had relatively less species and reactions.The comparison between the simulation results of detailed and reduced model revealed that the reduced model retained the precision of detailed model for quantitative prediction of most of main products.The higher simulation efficiency of reduced model can save calculation cost,which is suitable for engineering simulation.