Pyrolysis Mechanism Study Of Endothermic Hydrocarbon Fuel N-Decane At High Temperature

The aerocraft's cooling problem has already become increasingly important along with the hypersonic flight vehicle flight Mach number's unceasing increase. Scramjet engine works in combustion conditions of high velocity, high intensity combustion and high temperature. Conventional fuels may be limited in consideration of the cost of fuels' preparation and storage as well as the limitation of aerocraft size, while the high performance endothermic hydrocarbon fuels have the better application prospects. These fuels first crack into hydrogen and small molecule hydrocarbons with higher combustion performance by absorbing heat form the high temperature part of aerocraft, and then release the physical heat sink and chemistry heat sink through combustion in the burner. This kind of re cooling offers an effective way to heat management. So the endothermic hydrocarbons become one of the key technologies of the hypersonic.Enhancing the fuels chemistry heat absorption capacity is the effective method to increase the total heat sink when the physical properties have been confirmed. Therefore the pyrolysis and heat transfer characteristics of hydrocarbon fuels appear great significance of the thermal protection of scramjet engine.In this paper, the pyrolysis species distribution along with temperature is observed from pyrolysis of n decane at low and supercritical pressure. The kinetic model of n decane pyrolysis is developed according to the experiment measurements and previous kinetic studies, and the cracking path is obtained. The key reactions affecting the product's distribution are analyzed. This work can provided experimental data and theoretical guidance for the preparation and control of the reaction pathway of the endothermic hydrocarbon fuels.Firstly, supercritical pyrolysis experiment is carried out in the high pressure pyrolysis experimental system. Stable products are detected and the distribution along with temperature is obtained. Based on the experiment data, the heat sink curve of n decane is obtained through calculation and the endothermic law in supercritical condition is analyzed.Secondly, based on these experiment results, the detailed n decane mechanism is developed. By analyzing rate of product (ROP) and sensitivity, consumption channels of n decane, produce and consumption channels of methane, ethylene .etc are discussed. And the affecting mechanism of free radicals to product's distribution is analyzed.At last, molecular beam mass spectrometric technique coupled with tunable synchrotron VUV photo ionization method is applied to the pyrolysis investigation of n decane to comprehensively determine the pyrolysis species to especially the free radicals and intermediates at the National Synchrotron Radiation Laboratory (NSRL) in Hefei, China, and the distribution of main products is obtained. The n decane pyrolysis experiments under low pressure provide detailed data for the development of kinetic model.