Investigation Of Chemical Kinetic Mechanism For F-T Diesel Surrogate Fuel And Numerical Simulation

Coal-based F-T diesel is considered as a clean and efficient diesel fuel substitute since it features high cetane number,high combustion heat efficiency and low emission,and it can be mixed with petroleum-based diesel at any rate.In this study,a chemical kinetic skeletal mechanism for F-T diesel surrogate fuel was constructed for analysis F-T diesel combustion process in diesel engine.A series computational fluid dynamics(CFD)simulation for F-T diesel work process under different injection conditions were simulated by using the skeletal mechanism.The results of this paper have great significance for the in-depth understanding of the combustion process of F-T diesel in the cylinder.And it is in favour of high effectively and cleaning using of F-T diesel.Based on the component classes in the practical fuel,the F-T diesel surrogate model was including n-tetradecane and iso-octane.Frist,The main reaction path of alkanes macromolecular component was constructed by analyzing and simplifying the detailed mechanism of alkane.Then,the n-tetradecane skeletal mechanism was built,which combined with a C2-C3 sub mechanism and H2/ CO/ C1 detailed sub mechanism by using decoupling methodology.Finally,the surrogate fuel skeletal mechanism was including the n-tetradecane mechanism and a skeletal iso-octane macromolecular mechanism.The n-tetradecane mechanism contains 54 kinds of species and 175 recation,and the surrogate fuel mechanism contains 61 kinds of species and 187 reactions.Comparisons of the simulated and measured results indicated that the mechanism is capable of reproducing F-T diesel combustion characters.Using the mechanism,the engine CFD simulation based on engine test bench was simulated under different injection timing and duration.The results show that increasing the injection advance angle can increase the maximum combustion pressure,increase engine power,and reduce soot emissions,but it can increase NOx emissions obviously;The shorter duration of fuel injection can achieve the higher maximum combustion pressure,and make the soot emission declined,but it can increase NOx emissions.In conclusion,the engine can get good performance on economy and power under-13°CA injection advance angle and 9°CA-10°CA injection duration.