Experimental investigation on the combustion, performance and emission characteristics of a diesel engine using water emulsified diesel prepared by ultrasonication

Simultaneous reduction of both nitrogen oxides (NOx) and particulate matter emission from diesel engines can be done using water emulsified diesel (WED) as fuel. Its uses in CI engines also reduce the emissions of other pollutants such as carbon monoxide (CO) and smoke. In this paper, the authors have investigated experimentally the combustion, performance and emission characteristics of a single-cylinder, four-stroke diesel engine using WED prepared by ultrasonication methods containing 10% of water and compared these with those of pure diesel. WED has been produced by high-energy emulsification method using ultrasonicator. The water particle sizes in the emulsion, polydispersity index, stability, density and viscosity of the WED have been measured for the prepared emulsion. The observations show that the ultrasonication may be considered as an acceptable method for emulsification. The combustion characteristics show that the peak in-cylinder pressure and net heat release rate are higher for WED than those of pure diesel. Longer ignition delay is found for WED than that of neat diesel. However, the combustion duration is shorter. On the other hand, pure diesel and WED are comparable with respect to power, brake thermal efficiency (BTE) and brake-specific fuel consumption (BSFC). At higher load, increased BTE and decreased neat BSFC were found in case of WED. Emissions of pollutants like NOx and smoke reduce significantly, whereas HC emission increases. No significant difference is observed in CO emission at full-load condition between pure diesel and WED.