Effect of Air Injection Technique on the Emission Characteristics of a CI Engine During Transient Operation

The performance of turbocharged diesel engine deteriorates during transient operating conditions. Air injection is an effective technique in improving the transient response of the engine. However, the technique is not evaluated for exhaust emissions. To meet the stringent emission regulations, it is important to improve the emission performance of the diesel engine. Present study deals with the effect of air injection technique on exhaust emissions (CO, HC and NOx) under speed and load transients. Optimization of injection pressure based on orifice diameter is performed to ensure that the application of the technology comply with Euro VI standard. The results of the simulation were evaluated for Euro VI standard and 3 bar air injection at 10 mm orifice diameter was found to be the optimum injection pressure for speed transients which brings slight reduction in CO and HC emissions and significant reduction in NOxemissions. For load transients, Emissions werefound to be below Euro VI standard for all the injection pressures and orifice diameters.Quantification of emissions were done and 1.2 bar injection pressure at 10 mm orifice diameter was found to reduce all the three emissions as compared to no air injection.