Development of Diesel Engine Emissions Control Models Based on Heat Release Rate Analysis of Combustion Processes

Linear control models to control the Nitrogen Oxides (NOx) and soot emissions from a diesel engine were developed through numerical simulations. A modified KIVA-3V code was used to calculate the NOx and soot formations in a direct injection diesel engine under different operating conditions. The following relationships between the pollutant formations and the heat release rate were observed: 1) NOx formation amount is related to the peak value of the heat release rate and the timing of the premixed combustion; 2) soot formation amount is related to the peak heat release rate and the soot oxidation amount is related to the timing of the premixed combustion. Based on the above observations, linear control models for NOx and soot emissions were constructed. The NOx control model developed through the numerical simulations was implemented into the controller of an EGR valve on a small diesel engine. The experimental results showed that the NOx control model was effective in reducing NOx emissions under high RPM conditions.