Effects of Fuel Properties on Exhaust Emissions of a Single Cylinder DI Diesel Engine

In this study, the AVL 8-mode steady-state simulations of the EPA transient test were conducted on a two litre single cylinder Ricardo Proteus research engine using two fuel matrices, one consisting fuels having different cetane numbers and the other consisting fuels of different aromatic contents. Engine exhaust emissions of NO_x, HC, CO, CO₂ and particulates were measured at two different injection timings. The results show that the single cylinder engine behaves similarly as a number of multi-cylinder production engines. The 8-mode simulation was also shown to produce exhaust emissions close to those obtained from the EPA transient test procedure. The cetane number response of the research engine indicates that an increase in cetane number of the fuel with cetane improvers reduced NO_x emissions but increased particulate emissions. The response of the research engine to different aromatic contents suggests that cetane number, total aromatic content and the sum of the di-aromatic and the poly-aromatic contents are the major fuel properties affecting NO_x emissions. For particulate emissions, the sum of the di-aromatic content and the poly-aromatic content is the major factor. However, the number of fuels in the fuel matrix and the fuel matrix design are not satisfactory to claim universality for the observed relationship between aromatics and emissions.