Research On The Oxidation Mechanism Of Alkenes And Its Influence On Emission Of Gasoline Engine

Alkenes which are present in significant amount in gasoline can affect the engine combustion and emissions. Despite that there are very few kinetic modeling of the oxidation of alkenes, and there is no unified conclusion about the effect of alkenes on emission. Therefore, it is necessary to further study the mechanism of alkenes'oxidation.Alkenes influence the formation of NO,which can be decreased by using Exhaust Gas Recirculation (EGR). Therefore, a new computing model which combines the EGR to the calculation of chemical equilibrium concentration was generated. The results show that: With the increase of EGR rate, NO equilibrium concentration decreased, while CO equilibrium concentration increased. When the fuel air equivalence ratio decreased, NO equilibrium concentration increases.In order to research the combustion mechanism of alkenes, a reduced 1-pentene oxidation model was generated by means of temperature sensitivity analysis and flow rate analysis, which based on a detailed mechanism of 1-pentene. Comparing the calculated results of reduced mechanism and detailed mechanism, it shows that: The reduced mechanism is able to predict the 1-pentene oxidation process correctly. In order to study the effect of alkenes on NO emission, a NO generation module was added into the reduced mechanism to form a new model which can predict NO generation. The results show that: The new model is able to predict NO generation in different boundary conditions.To study the impact of alkenes content in gasoline on emissions, gasolines with different alkenes content were selected to engine test which was carry out by two engines. Engine 1 is a carburetor engine, and engine 2 is a EFI (Electronic Fuel Injection) engine. The results show that: There is a significant difference of the emissions between the two engines. With the increase of alkane and the decrease of alkene, as to engine 1, HC emissions increase obviously, and there is an increasing tendency of CO together with a decreasing tendency of NO. While,as to engine 2, the NO emissions decrease gradually together with no significant change of CO and HC.