Contribution of Different Diesel Fuel Injection Systems to Engine Out Emissions

Diesel engine manufacturers use various approaches to meet stringent emission standards. These approaches vary from advanced in-cylinder emission reduction strategies to sophisticated after-treatment solutions. Fuel injection system plays a very critical role in the design of a fuel efficient engine that complies with emission regulations. This paper highlights a comparison of common rail (CR) vs. amplified injection (AI) fuel systems on engine out emissions. The study was conducted on a four stroke, six-cylinder, turbocharged diesel engine using cooled exhaust gas recirculation (EGR). Both the CR and AI fuel systems were tested on the same engine hardware. The maximum injection pressure of multiple shot capable CR and single shot capable AI fuel systems are 2000 bar and 2700 bar respectively. Emission results are summarized at two critical steady state points. Higher injection pressure in the simplified AI fuel system shows a potential alternative to exceed the maximum injection pressure limits of CR fuel system for the same engine performance envelope. The NOx to soot trade off window with AI fuel system allows for lowering emissions with higher injection pressure. Nozzle spray geometry is an important factor in reducing emissions at higher injection pressure with an AI fuel system.