An Optical Study of Spray Development and Combustion of Ethanol, Iso-Octane and Gasoline Blends in a DISI Engine

Document Number: 2008-01-0073

Date Published: April 2008

Author(s):
Pavlos Aleiferis - University College London
John Malcolm - University College London
Alan Todd - MAHLE Powertrain Ltd.
Alasdair Cairns - MAHLE Powertrain Ltd.
Hermann Hoffmann - MAHLE International GmbH

Abstract:
In recent times regulatory pressure to reduce CO\d2 emissions has driven research towards looking at blending fossil fuels with alternatives such as crop-produced alcohols. The alcohol of interest in this paper is ethanol and it was studied in mixtures with gasoline and iso-octane in an optical spark-ignition engine, running at 1500 RPM at low-load operation with 0.5 bar absolute intake plenum pressure. Specifically, tests involved fuels of 100% gasoline and 100% iso-octane, so that differences between multi and single-component fuels could be compared within this environment. A mixture of 25% ethanol with 75% iso-octane was also tested and compared. Finally, mixtures of high-percentage of ethanol (85% ethanol) in gasoline and in iso-octane were used in the study and compared. Tests were undertaken using a standard port injection system as well as a direct injection system so an appraisal of both mixture preparation methods could be made. Initially, a high-speed imaging study of the in-cylinder spray formation was undertaken with the direct injection system for different injection timings and engine-head temperatures under motoring engine conditions. The engine was also run with continuous firing using all fuels. In-cylinder pressure data were collected at 0.2\mD crank angle resolution for each cycle and synchronized with simultaneous high-speed flame imaging at 1\mD crank angle resolution for a series of 100 consecutive cycles for all test points. The flame images were processed to quantify the evolution of an equivalent flame radius.

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Included in: SP-2169

See other papers presented at SAE World Congress & Exhibition, April 2008, Detroit, MI, USA, Session: Renewable Fuels

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