A phenomenological modelling framework for particle emission simulation in a direct-injection gasoline engine

A phenomenological modelling framework is presented that allows the simulation of the engine-out particle emissions of direct-injection gasoline engines based on physical principles. It is applicable both at steady-state operating conditions and in transient driving cycles. Within the modelling framework, a multi-zone model with gas-phase reaction kinetics is coupled with a stochastic reactor model considering the soot formation dynamics. Both model parts are fed with inputs from an accompanying engine process simulation. Particle emissions from injector deposits and inhomgeneous gaseous mixture preparation are taken into account. Pyrolysis reactions are considered in a zone with remaining fuel film at the injector, whereas in gas-phase zones that arise from inhomogeneous mixture preparation, the reaction of the air-fuel mixture is calculated under sub-stoichiometric conditions. The setup of those mixture-induced zones is generated by an existing homogenisation sub-model. The modelling framework is evaluated by test bench measurements of the engine operating map, a variation of engine actuator settings and transient driving profiles. Hereby, an accuracy of less than 20% deviation for particle number and mass is achieved.