Multi-zone model for diesel engine simulation based on chemical kinetics mechanism

Highlights: • A new multi zone model is developed to diesel engine simulation. • Chemical kinetics mechanism is coupled to multi zone model. • The model considers the heat and mass transfers between the zones. • Fick's law is used to calculate the rate of diffusion mass transfer. - Abstract: The main purpose of this study was to develop a new multi-zone model for simulating the diesel engine's closed loop. The proposed multi-zone model is based on chemical kinetics and uses a semi-detailed chemical kinetics mechanism containing 76 species and 327 reactions to calculate the fuel burning rate at each time step. This chemical kinetics mechanism contains 6 reactions to simulate soot formation and 14 reactions to simulate NOx formation. Prior to fuel injection, the combustion chamber is divided into three zones: inner zone, boundary layer zone, and crevice zone. The model considers the heat and mass transfers between the zones. Convective and radiation heat transfers are considered between the boundary layer zone and combustion chamber walls. When fuel injection begins, the spray is modeled and a zone is formed that contains the fuel jet. The geometry of the fuel jet zone is estimated using the spray-cone angle, and the length of this zone (fuel jet) is estimated using the Higgin's correlation. The spray-cone angle is calculated using the Reitz and Bracco's correlation. Fuel spray penetration into other zones is calculated using the Wakuri's relation. Fick's law is used to calculate the diffusion rate of different species in each zone. The model results are in good agreement with experimental data in predicting the in-cylinder pressure, the start of the combustion time, combustion duration, and emissions. The maximum error of model for predicting soot and NOx are 17% and 12%, respectively.