Diesel engine performance and emission characteristics using three-phase emulsions as fuel

Diesel engines are employed as the major propulsion power source for both in-land and marine transportation primarily because of their simple, rigid structure and high fuel economy. It is expected that diesel engines will be widely used in the foreseeable future. However, the pollutants emitted from diesel engines, in particular nitrogen oxides and particulate matter, which are detrimental to the health of living beings and the ecological environment, have been recognized as a major air pollution source in metropolitan areas. This situation has attracted much research interest. Diesel oil emulsions have been used as one of many possible approaches to reduce diesel engine pollution. Previous relevant applications are been restricted to water-in-oil (W/O) two-phase emulsions. Three-phase emulsions, such as oil-in-water-in-oil (denoted as O/W/O) and water-in-oil-in-water (denoted as W/O/W), have not been used as alternative fuels for combustion equipment. The engine performance and emission characteristics using multi-phase O/W/O test fuels for diesel engines were investigated in this experimental study. The results show that using O/W/O or W/O emulsions resulted in lower exhaust gas temperatures and lower NO,, CO emission and smoke opacity. The O/W/O emulsion appeared to produce higher exhaust gas temperatures but lower CO and NOx emissions in comparison to W/O emulsions with the same added water proportion. (C) 2004 Elsevier Ltd. All rights reserved.