Research On Combustion And Emission Mechanism Of F-T Diesel

Compared with traditional diesel,F-T diesel can shorten the ignition delay time,improve engine combustion characteristics and has low emission.It is considered as a clean and efficient alternative fuel for diesel engines.As a subsidiary product of chemical process,F-T diesel has the adjustable characteristics and inconsistent physical properties.In order to flexibly explore the combustion and emission characteristics of F-T diesel with different components.This paper simplifies the detailed mechanism of F-T diesel,applies the simplified mechanism to numerical simulation,and calculates the working process of F-T diesel under different injection parameters.It can be used as a reference for exploring the causes of the combustion and emission characteristics of F-T diesel.Based on the determination of F-T diesel components,the result shows that n-tetradecane and isooctane are suitable as the F-T diesel surrogate model.In the process of analyzing and characterizing the chemical mechanism of fuels,Frist,the detailed mechanism of n-tetradecane is analyzed and simplified by Direct Relation Graph(DRG)method and Computational Singular Perturbation(CSP)method.Then,the accuracy of the simplified mechanism is verified.The result indicated that:This mechanism can accurately predict the delay time,main component consumption and laminar flame propagation velocity of n-tetradecane.Finally,the F-T diesel surrogate mechanism was built,which combined with the simplified n-tetradecane mechanism,a skeletal iso-octane macromolecular mechanism and formation mechanism of NO_x.It contains 66kinds of species and 186 reactions.Comparing the experimental data of emission generation with the calculated value of simplified mechanism,it is found that there are little deviations between them.Combustion and emission characteristics of F-T diesel fuel under different injection parameters were calculated based on a multi-dimensional combustion model and simplification mechanism.The results show that increasing the injection advance angle and shortening the injection duration properly can increase the in-cylinder pressure,improving engine power performance,but will increase the emission of NO_x and CO at the same time.