Optimization of Fuel Injection Parameters for Meeting Euro III Exhaust Emission Norms on a Heavy Duty Diesel Engine Using Taguchi Technique 2008-01-1610

Diesel engine performance is being continuously enhanced in the last decades in pursuit of high power density, improved fuel economy and low emission compliance. Developments in combustion technologies, advanced electronic fuel injection, refined engine and injection parameters have helped engineers tune eco-friendly diesel engines resulting in simultaneous NOx-PM reduction. Understanding engine and injection parameters and their effects on exhaust emissions is vital for producing cleaner diesel engines and is therefore a subject of intense research.

The scope of this work was to optimize the influence of injection parameters on regulated emission constituents of diesel exhaust to meet Euro III emission norms on a heavy duty diesel DI engine. Carefully tailored design of experiments and Taguchi technique were used to meet the project objectives due to short development time. The best injection parameters were isolated from experimental results of L₉ orthogonal array using Analysis of Means (ANOM), Signal-to-noise ratio (S/N) and Analysis of Variance (ANOVA). The results from analysis are validated to meet Euro III emission targets consistently with defined engineering margins on emission components.

In this investigation, influence of parameters namely cam velocity, nozzle through flow, nozzle tip protrusion into the combustion chamber and number of spray orifices were studied. Of the four injection parameters evaluated, cam velocity affecting injection rate and number of nozzle spray orifices affecting injection pressures and atomization of spray played an influential role in reduction of NOx and PM. In addition, nozzle tip protrusion affecting the point at which nozzle spray jet impinges into the combustion bowl only moderately influenced the PM and HC emissions. Nozzle through flow effect on emission constituents of diesel exhaust is almost negligible for meeting Euro III exhaust emission norms in the defined experimental region. Euro III emissions targets were met consistently in totality with more than 11.5% margins on NOx, 61.5% on CO, 76.5% on HC and 23% on PM compared to federal Euro III limits. Further, engine power and torque characteristics were enhanced by 30% compared to base engine performance together with 10.6% reduction in full load SFC with intent of improving overall driveability and fuel economy of the vehicle.