Novel Strategies and Optimization Techniques to Reduce Harmful Diesel Engine Emissions

Abstract

This article presents experimental and optimization work in developing a premixed charged compression ignition (PCCI) combustion diesel engine characterized in a low emission vehicle. An overall process to achieve PCCI combustion in a diesel engine is described, and effects of engine operating parameters such as exhaust gas recirculation rate, injection pressure, swirl ratio, and intake pressure along with injection features for fuel consumption and harmful engine-out emissions are evaluated. A late intake valve closing (LIVC) strategy was employed for further reduction in particulate matter (PM) and nitrogen oxide (NOx) emissions without sacrificing fuel economy. Design of experiments was used to evaluate the effect of three selected operating parameters and their interactions on the emission and fuel consumption characteristics of the PCCI engine. Upon optimization it was found that NOx and PM emissions could be simultaneously decreased 57% and 39%, respectively, compared to the emission level of a conventional diesel engine.