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The environmental impact of internal combustion engines has led to increasing governmental regulations regarding the emissions and fuel economy performance of internal combustion engines. The DI Diesel engines, having the evident benefit of a higher thermal efficiency than all other engines, have served for both light- duty and heavy-duty vehicles. But, direct injection diesel engines emit more particulates and oxides of nitrogen than their counterpart and that is a challenge. The NOx+HC limits for CEV BSIII regulations is 4.00 g/ Kw-Hr,3.8 g/Kw-Hr with deterioration factor[DF] against the 10.50 g/Kw-Hr of CEV BSII regulations, which is over 60% reduction in gaseous emissions. Now after this stringent targets defined it is essential to understand the NOx formation.

During the design stage, certification testing, or in field problem solving, t is of value for engine designers and engineers to have an understanding of how robust the engine design is to variation in the manufacturing process, in-use wear, controller and the testing processes. In this paper, a sensitivity analysis is performed on a parametric GTpower diesel engine model and using Robust Design methods NOx defects are reduced. Sensitivity analysis is conducted using a Plackett-Burman DOE. The DOE is performed on a 6 cylinder, direct-injection, turbocharged diesel engine model in GTpower, while Minitab is used for the experimental design and the factorial sensitivity analysis. It was found that the NOx population distribution was unacceptably high, yielding a 7.4% defect rate relative to an upper control limit of 5 (g/kw-hr).