Improving the Combustion and Emissions of Direct Injection Compression Ignition Engines Using Oxygenated Fuel Additives Combined with a Cetane Number Improver

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• 作者：Xing-cai L&uuml ; Jian-guang Yang ; Wu-gao Zhang ; and Zhen Huang
• 刊名：Energy & Fuels
• 出版年：2005
• 出版时间：September 2005
• 年：2005
• 卷：19
• 期：5
• 页码：1879 - 1888
• 全文大小：555K
• 年卷期：v.19,no.5(September 2005)
• ISSN：1520-5029

文摘

According to the fuel design concept, three oxygenated fuels including ethanol, dimethylcarbonate (DMC), and dimethoxy methane (DMM) were selected to mix with diesel fuel. Then,the effects of oxygen content and the cetane number of the blend fuels on diesel engine combustionand emissions were evaluated. The experiments were conducted on a four-cylinder high-speeddiesel engine. The results show that, with the increase of the oxygen content in blend fuels, theignition timing delays and the combustion duration shorten at different operating conditions,and the brake thermal efficiency improves from middle to full loads. The engine NO_x emissionsdecreased at overall operating ranges when oxygenated fuels were added to the diesel fuel, andsmoke emissions also improved for all oxygenated blend fuels except for ethanol-diesel blendsat low and middle loads. In the case of the DMC-diesel blend fuel, when the oxygen contentincreased up to 15%, the smoke number decreased by 75%, and NO_x emission improved by15-20%. CO emissions of blend fuels decreased at large and full loads but deteriorated at lowerand middle engine loads. HC emissions increase at overall operating ranges and increase muchmore with the increase of oxygenated fuel volume and decrease of the engine load. To solve thisproblem, the cetane number improver was added to the 15% ethanol-diesel blend fuel. As aresult, the HC and CO emissions at overall operating ranges reduce substantially, and NO_xemissions further reduce, but smoke emission maintains the same level when compared to theethanol-diesel blend fuels without the cetane number improver. According to the heat releaserate analysis, it can be found that the combustion characteristics of an ethanol-diesel blend fuelat large loads may be resumed to diesel fuel by the CN improver but that a large differenceexists at lower loads.