Experimental Research In Influence Of Oxygenated Biomass Fuel On Diesel Engine Performance, Combustion Procedure And Emission Characteristics

Nowadays energy sources lack and environment pollution are main difficulties in the world. Although diesel engine is more and more popular for stability and high thermal efficiency, it has defects of high NO_x emission and Soot emission, caused by diffusive combustion mode, between which exists "trade-off' relationship. As oxygenated biomass fuel, ethanol and biodiesel oil are oxygen self-supported, widely sourced and regenerated. Mixing diesel oil with ethanol or biodiesel oil, could reduce emission effectively and meet the requirement of emission reduction and petrol-energy sources crisis easing.This research was carried on a pressure-enhanced, inter-cooled diesel engine, included experiments on load characteristics at 1500r/min, the highest torque rotate speed, and at 2300r/min, rate speed. It is studied that the influence of mixing diesel oil with ethanol or biodiesel oil on diesel engine performance, combustion procedure and emission characteristics, also that with unchanged proportion of diesel oil the influences compare between different oxygenated fuels, like ethanol, biodiesel oil, mixture of ethanol and biodiesel oil at ratio of 1:1, etc., on diesel engine performance, combustion procedure and emission characteristics.The result shows that when taking ethanol and diesel oil as mixture fuel, its fuel consumption is similar as that of using diesel oil, only a bithigher at low load condition. With the increase of ethanol proportion, the appearance of pressure peak is delayed, the highest rising rate of pressure is increased and its appearance also be delayed, the max in-cylinder pressure is developed a little at 1500r/min then falls down at 2300r/min, the heat release of pre-combustion is postponed and its peak is increased. As for emission, both NO_x and Soot emission decrease in different degrees comparing ethanol-diesel to diesel. Speed has strong effect on HC and CO emission. With the increase of ethanol proportion, both HC and CO emission have some reduction at 1500r/min, then have some enhance at 2300r/min.Comparing the condition of using mixture of diesel oil and biodiesel oil and that of using diesel oil, their fuel consumptions are similar, both the max in-cylinder pressure and the highest rising rate of pressurein first condition are lower that that in the second condition. Also the heat release peak is lower, with the increase of biodiesel oil proportion, its appearance is later and then earlier. As for emission, both NO_x and Soot emission in two conditions have decrease in different degrees. HC and CO emission are reduced at 1500r/min, and in first condition with the increase of ethanol both of them are decreased. When at 2300r/min HC and CO emission are at high side in different conditions, but have some decrease at high load condition.In the research on influences compare between different oxygenated fuels on diesel engine performance, combustion procedure and emission characteristics, mixing diesel oil with ethanol or biodiesel oil will relax the "trade-off"relationship between NO_x and Soot emission. And compared with the condition of mixing biodiesel oil, mixing with ethanol has advantages in lower fuel consumption, lower NO_X and Soot emission, but has higher max in-cylinder pressure, higher rising rate of pressure ,higher HC and CO emission. The oxygenated fuel, including ethanol, diesel oil and biodiesel oil, has their separate advantages, could overcome the defect in instability of mixture of ethanol and diesel. It is a new way to spread ethanol and biodiesel usage, ease petrol-energy sources crisis and reduce the diesel engine emission.