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Title: Effects of ethanol on combustion and emissions of a gasoline engine operating with different combustion modes
Authors: Ojapah, MM
Zhao, H
Zhang, Y
Keywords: Science & Technology;Physical Sciences;Technology;Thermodynamics;Engineering, Mechanical;Transportation Science & Technology;Engineering;Transportation;Early intake-valve closing;Positive valve overlap;Controlled auto-ignition;Gasoline direct injection;Ethanol;Gasoline particulates;Aerodynamic Diameter Measurements;Density Characterization;Particle Morphology;Combined Mobility
Issue Date: 2016
Publisher: Sage Publications Ltd
Citation: INTERNATIONAL JOURNAL OF ENGINE RESEARCH, 17 (9): pp. 998 - 1011,(2016)
Abstract: The introduction of fuel economy and CO2 emission legislations for passenger cars in many countries and regions has spurred the research and development of more efficient gasoline engines. The pumping loss at part-load operations is a major factor for the higher fuel consumption of spark ignition (SI) gasoline engines than the diesel engines. Various approaches have been identified to reduce the pumping loss at part-load operations, leading to improved fuel economy, including Early Intake Valve Closing (EIVC), Positive Valve Overlap (PVO) and Controlled Auto-Ignition (CAI) combustion. On the other hand, in order to reduce the CO2 emissions from the fossil fuel, ethanol produced from renewable resources is becoming widely used in the gasoline engine. In this paper, the performance, combustion and emissions were measured, analyzed and compared between gasoline and its mixture with ethanol (E15 and E85) at a typical part-load condition when a direct injection gasoline engine was operated with the CAI combustion by means of the negative valve overlap (NVO) and SI combustion by means of the intake throttled, EIVC and PVO. An electro hydraulic actuated camless system enabled the engine to be operated with CAI combustion and SI combustion of different valve timings and durations at the same load. The results showed that the CAI combustion reduces NOx emissions by more than 90%. The PVO results in better mixture preparations and improved combustion efficiency and best fuel economy compared to all the other modes. The EIVC operation led to a moderate improvement in the fuel conversion efficiency over the throttled SI operation but it was characterised by the slowest combustion and worst HC and CO emissions. Fewer and smaller particles numbers were detected in EIVC using E0 and E15 fuel blends. Using ethanol blends reduces the knocking combustion in CAI modes by about 50%. The use of E85 resulted in an increased number of particulate emissions in EIVC but increased ISFC in all the modes. The particulate emission results showed that soot is the dominant particle in the exhaust.
Appears in Collections:Dept of Mechanical Aerospace and Civil Engineering Research Papers

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