ABSTRACT
A compression-ignition engine with di-methyl ether (DME) could emit almost zero smoke emissions due to better mixing property (high diffusivity) with air. This chapter details the main biofuels for compression-ignition engines. Since the cetane number of biodiesel is higher than that of petroleum diesel, in general, the cold-start ability and transient emissions of a compression-ignition engine with biodiesel would be better than the engine fueled with petroleum diesel. Emissions, such as CO, HC, and smoke/particulate matter (PM), are less in biodiesel-fueled compression-ignition engines as compared to base diesel. Fuel with high injection pressure is directly injected into the cylinder by the injectors at the end of a compression stroke. Less PM emission with biodiesel is due mainly to the absence of sulfur, aromatic components, and fuel-embedded oxygen. However, NOx emission in an engine with biodiesel is higher than base diesel and power output of the engine would drop with biodiesel.
