Emission Characteristics of a Navistar 7.3L Turbodiesel Fueled with Blends of Dimethyl Ether and Diesel Fuel

Several oxygenates have been proposed and tested for use with diesel fuel as a means of reducing exhaust emissions. This paper examines dimethyl ether (DME), which can be produced in many ways including via Air Products and Chemicals, Inc's Liquid Phase Technology (LPDME ™). Modest additions of DME into diesel fuel (2 wt.% oxygen) showed reductions in particulate matter emissions, but the previous data reported by the author from a multicylinder Navistar 7.3L Turbodiesel engine were scattered. In this study, experiments were performed on a multi-cylinder Navistar 7.3L Turbodiesel engine to repeatably confirm and extend the observations from the earlier studies. This is an important step in not only showing that the fuel does perform well in an engine with minor modifications to the fuel system, but also showing that DME can give consistent, significant results in lowering emissions. The DME and diesel blends tested were to achieve a net addition of 5 and 10 wt. % oxygen in the blended fuel. The data confirms that the addition of DME can reduce the particulate emissions from a compression ignition engine. However, the NO_x emissions were not favorable for all conditions. It is believed that through further modification of injection timing, NO_x emissions can be effectively reduced.