Modelling of internal combustion engine processes an emissions

In the present study, thermodynamic cycle simulation of reciprocating internal combustion engines using simple and efficient methods is aimed. In the simulation, engine processes are divided into sub processes and evaluated with the computer simulation code. Simulation for both CI (Compression Ignition) and SI (spark ignition) engines are evaluated for performance and emissions. Thermodynamic simulation is performed using energy balance, mass balance and ideal gas equations. Heat release rate, heat transfer, ignition delay, and emission formations are modeled as sub processes. Combustion chamber is divided into multi zones, and closer to real in-cylinder values are used rather than mean ones to obtain better emission predictions. And effects of engine parameters, i.e. bore, stroke, combustion start and combustion duration, on engine performance and emissions are investigated. In the zero dimensional simulation, using two and three zone combustion models, state variables in the combustion chamber are evaluated. In the three zone model, in addition to burned and unburned zones, crevice volume is taken as the third zone. The two zone model is applied to a CI engine and the three zone model is applied to a SI engine. Higher charge temperatures at combustion start causes higher emission levels. Combustion start and duration affects formation of NOx and HC emissions, considerably. Closer the combustion start to TDC or longer the combustion duration, causes reduction in emissions. With including crevice volume into the simulation and it is presented that, due to decrease in crevice volume, particularly, significant reduction in HC emissions can be achieved. Keywords: Internal Combustion Engine, Engine Process Simulation, Combustion Models, Emissions.