DEVELOPMENT OF A COMPREHENSIVE TWO ZONE MODEL FOR COMBUSTION AND EMISSIONS PREDICTION IN A DIRECT INJECTION (DI) DIESEL ENGINE

A two zone model for the calculation of the closed cycle of a compression ignition direct injection (DI) diesel engine is developed. This model divides the cylinder contents into a non-burning zone of air surrounding the fuel spray jets issuing from injector nozzle holes and another homogenous zone in which fuel is supplied continuously from injector and burned with entrained air from the air zone. The growth of the fuel spray zone in the combustion chamber, consisting of a number of fuel-air conical jets equal to the injector nozzle holes, is carefully modeled by incorporating jet mixing and main relevant spray parameters. Application of the mass, energy and state equations in each one of the two zones yields local temperature and cylinder pressure histories. Furthermore, compression stroke, heat transfer, ignition delay period, rate of combustion, pollutants formation and expansion stroke are considered in this thermodynamic modeling. For the calculation of the constituents in exhaust gases, a chemical equilibrium scheme is adopted for the C-HO- N system of 11 species considered. The precise amount of nitric oxide (NO) in exhaust gases is calculated by a chemical kinetics model. Also, the soot formation process is modeled by considering both the formation and oxidation processes in net soot formation. Eventually, the theoretical results are validated against experimental results and a multiparametric study has been done to show the effects of various important parameters on emissions and incylinder pressure.

کلیدواژه ها:

Direct Injection Diesel Engine ، Emissions ، Modeling ، Performance ، Simulation