Investigation On Combustion And Emissions Characteristics Of2-Methylfuran Gasoline Blends In A Spark-Ignition Engine

Today, petroleum-based fuels are still the main power of internal combustionengines, problems of oil shortage and air pollution caused by the combustion ofpetroleum have become great issues all around the world. Development andapplication of clean alternative fuels for internal combustion engine is considered tobe one of the effective medium, short-term solution.2-Methylfuran can be preparedby non-food biomass, which has relative high research octane number and property ofwater-insoluble. The fuel energy density of2-methylfuran increases by about16%compared with ethanol, thus making it very competitive as a gasoline substitute fuel.Investigating of combustion and emissions characteristics of2-methylfuran and itsblend fuels in a spark-ignition engine is beneficial to its promotion and developmentas an alternative fuel, which providing theoretical basis for its further application andoptimization.In this work, effects of burning2-methylfuran or low proportional blending itwith gasoline as an additive on engine combustion and emissions characteristics werefirstly investigated in a spark-ignition engine at various engine loads. The resultsindicated that burning pure2-methylfuran or blended fuels caused the followingchanges：More advanced ignition timing can be allowed at high loads, which meansthe fuel antiknock ability is enhanced; Ignition delay and combustion duration areshortened compared with that of gasoline, thus reducing the engine combustion cyclevariations; Indicated thermal efficiency is slightly improved, but lower energy densityleads to relative high fuel consumption rate; Regulated gas emissions of HC and COdecreased compared with that of gasoline, which is mainly due to its oxygenated fuelmolecules and relative high combustion temperature；Higher cylinder peak pressuresand maximum mean temperatures result in significant increased NOXcompared withthat of gasoline. When the indicated mean effective pressure is1.2MPa, adding20%volume2-methylfuran causes about8.3%increase in indicated specific NOXemissions.Focus on the problem of NOXemissions increase caused by burning2-methylfuran, combining with exhaust gas recirculation (EGR), this work alsoinvestigated the engine performance and emissions at various EGR rates, the effect ofEGR on combustion and emissions characteristics for two fuels were compared andanalyzed. The results show that, because of smaller hydrogen-carbon ratio of2-methylfuran, the exhaust gas heat capacity is lower than that of gasoline, whichleads to the effect of EGR on engine performance and emissions weakened. When theEGR rate is10%, reduction of cylinder maximum mean temperature for burninggasoline is about208K, and NOXemissions decrease about56%, while the values for burning2-methylfuran are140K and26%, respectively. Therefore, fueled with2-methylfruan in spark-ignition engines needs to use larger EGR rates to optimize itsNOXemissions.