Experimental Investigation on the Use of Water Diesel Emulsion with Oxygen Enriched Air in a DI Diesel Engine

A single cylinder, direct injection diesel engine was run on water diesel emulsion at a constant speed of 1500 rpm under variable load conditions. Water to diesel ratio of 0.4 on the mass basis was used. Tests indicated a considerable reduction in smoke and NO levels. This was accompanied by an increase in brake thermal efficiency at high outputs. HC & CO levels, ignition delay and rate of pressure rise went up. The heat release rate in the premixed burn period was higher. When the oxygen concentration in the intake air was enhanced in steps up to 25% along with the use of water diesel emulsion, the brake thermal efficiency was improved and there was a further reduction in the smoke level. HC and CO levels also dropped. NO emission went up due to increased temperature and oxygen availability. An oxygen concentration of 24% by volume was optimal as the NO levels were near about base diesel values. With this percentage of oxygen and water diesel emulsion as fuel, the smoke level reduced from 5.3 BSU to 1.3 BSU at the maximum output tested. HC level was lower than diesel values and CO emission showed a similar trend at high outputs.