Investigation On The Performance And Emission Of Oxygenate Alternative Fueled Diesel Engines

Many approaches including in-cylinder combustion control and exhaust after-treatment are taken in recent decades to satisfy the increasingly strict engine emission regulations. However, the trade-off relation between reducing NO_X and particulate matter (PM) from the engine exhausting gas, because NO_X and PM are produced from contradictious conditions. It is great challenge in the engine field to simultaneously reduce both NO_X and particulate matter without degrading engine economic performance. In recent years, the engine alternative fuels attract more attentions from engine researchers due to the energy resource and environment problems getting increasingly serious. According to the particularity of resource in our country, it is very important to develop new clean alternative fuels, which can improve the atmospheric quality, change energy structure, lighten dependency for oil, and ensure national energy security.In this study, the diesel engine fueled with oxygenated alternative fuels, such as ethanol/diesel, dimethyl carbonate (DMC), dimethoxy methane (DMM) and dimethyl Ether (DME), were investigated. The work is as following:(1) Engine performance and exhaust emission as well as engine combustion were studied and analyzed when fueled with mixtures of 5%~20% ethanol in diesel. The results showed that using the oxygenated ethanol/diesel compounds as fuel, the engine emission can be reduced and combustion be improved while the engine power hardly influenced. It can be drawn that ethanol is one of the best oxygenated additive for diesel engine and may be popular used someday.(2) Experiments of diesel engine fueled with 5%~20% dimethyl carbonate (DMC) blended in diesel showed that it could improve the engine combustion and decreased the PM and NOx exhaust emissions so that DMC is a good oxygenated alternated fuel for diesel oil.(3) The oxygenated DMM and DME as diesel alternative were tested on diesel engine test-rig. Results showed that both of them can improve the engine performance. However, for the high boiling point of DMM, the engine could not run steadily and it is hard to be used without changing engine fuel delivery system. On the other hand, DME is an excellent diesel oxygenated alternative fuel.From the study, we can draw the conclusions:(1) Adding oxygenated additives into the diesel will improve the combustion performance and decrease the exhaust emission effectively, especially decrease the PM discharge obviously. The study shows that the carbon smoke emission decreased monotonously when the oxygen contained more.(2) The oxygenated additives decrease the exhaust emission in some extends. Because of the burning temperature in the cylinder decrease when the oxygenated additive content increases, diesel engine NOx emission reduced in trend. However, the NOx emission increase...