An experimental study of surrogates of diesel from indirect coal liquefaction and the development of an improved kinetic mechanism

The increasing energy shortage and environmental pollution make the use of clean and efficient alternative fuels an effective way to solve the emission problem. Diesel from indirect coal liquefied (DICL) is a clean and efficient alternative fuel for diesel engines. The composition and chemical kinetics mechanism of DICL research contributes to a better understanding of combustion and pollutant formation process. The components of DICL were analysed by gas chromatography-mass spectrometry (GC-MS). The proportion of normal alkanes contained in DICL is particularly high, 93.82%, which proves that its reactivity is particularly good. The mixture of n-dodecane and iso-octane was selected as the surrogates of DICL. The oxidation process of DICL surrogates was examined by a jet-stirred reactor (JSR) over the temperature range of 500-890 K. A detailed kinetic mechanism of surrogates encompassing 1356 species and 6008 reactions was constructed. The critical reactions associated with the reactivity of surrogates were adjusted by the sensitivity analysis method to increase the accuracy of mechanism prediction. The predicted value of the improved mechanism is in good agreement with the experimental value. The improved mechanism can reasonably predict the oxidation process and the ignition characteristics of DICL and the improved mechanism can provide a good reference value for the subsequent analysis of combustion and emission problems of DICL.Abbreviations: C/H, C/H ratio; CN, cetane number; DDCL, direct coal liquefy diesel; DICL, Diesel from indirect coal liquefied; GC-MS, gas chromatography-mass spectrometry; HMN, 2,2,4,4,6,8,8-heptamethylnonane; HXN, n-hexadecane; IDT, ignition delay time; JSR, jet-stirred reactor; LHV, low heating value; LLNL, Lawrence Livermore National Laboratory; NSRL, National Synchrotron Radiation Laboratory; NTC, negative temperature coefficient; PICS, photoionization cross section; PRF, gasoline substitute; PSR, perfectly stirred reactor; SVUV-PIMS, Synchrotron VUV photoionization mass spectrometry; TOF-MS, time-of-flight mass spectrometer