Role of the Chemical Kinetics on Modeling NOx Emissions in Diesel Engines

New diesel engine strategies (involving high injection pressure and multiple injections) have been proposed in recent years aiming to reduce pollutant emissions (mainly NOx and particulate matter). These strategies have led to very fast combustion processes as a consequence of the improvement on the fuel atomization, evaporation, and air entrainment phenomena. Although NOx emissions models for diesel engines usually assume equilibrium and/or the steady state hypothesis together with the consideration of very simplified kinetic reaction mechanisms (such as the Lavoie method based on the extended Zeldovich reaction mechanism), modern diesel engine combustion models require more complex chemical kinetic approaches due mainly to the lack of time to reach the equilibrium state. These kinetic considerations are even more important for simulating new diesel combustion concepts (such as homogeneous charge compression ignition (HCCI) and low temperature combustion (LTC)), which are well-known to be kinetically con...