The influence of straight vegetable oil fatty acid composition on compression ignition combustion and emissions

Hellier, Paul and Ladommatos, Nicos and Yusaf, Talal (2015) The influence of straight vegetable oil fatty acid composition on compression ignition combustion and emissions. Fuel, 143. pp. 131-143. ISSN 0016-2361

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This paper presents experimental studies carried out on a modern direct injection compression ignition engine supplied with a range of straight vegetable oils to investigate the effect of oil fatty acid composition on combustion and emissions. Seven oils, those of corn, groundnut, palm, rapeseed, soybean, sunflower and the micro-algae species Chlorella protothecoides were tested, with all of the fuels heated to 60°C, at constant injection timing and constant ignition timing at a constant engine speed of 1200 rpm. All of the vegetable oils exhibited a duration of ignition delay within ±0.6 CAD of that displayed by a reference fossil diesel, but displayed much reduced rates of peak heat release rate. The duration of ignition delay was found to increase with an increasing carbon to hydrogen ratio of the vegetable oils, implicating the fatty acid alkyl chain as the primary driver of low temperature reactivity. Peak heat release rates decreased with decreasing vegetable oil viscosity, suggesting a significant degree of fuel cylinder wall and piston bowl impingement. At both injection timings, emissions of NOx were lower for all of the vegetable oils relative to the reference fossil diesel, while those of CO, THC and particulate matter were higher and sensitive to the injection timing.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: This is an open access article under the CCBY license ( This publication is copyright. It may be reproduced in whole or in part for the purposes of study, research, or review, but is subject to the inclusion of an acknowledgment of the source.
Faculty / Department / School: Current - Faculty of Health, Engineering and Sciences - School of Mechanical and Electrical Engineering
Date Deposited: 11 Feb 2015 23:07
Last Modified: 24 Jun 2016 05:25
Uncontrolled Keywords: biofuels; diesel combustion; fatty acid structure; micro-algae; vegetable oil
Fields of Research : 09 Engineering > 0907 Environmental Engineering > 090703 Environmental Technologies
09 Engineering > 0902 Automotive Engineering > 090201 Automotive Combustion and Fuel Engineering (incl. Alternative/Renewable Fuels)
10 Technology > 1003 Industrial Biotechnology > 100302 Bioprocessing, Bioproduction and Bioproducts
Socio-Economic Objective: B Economic Development > 85 Energy > 8503 Preparation and Production of Energy Sources > 850309 Production of Biofuels (Biomass)
Identification Number or DOI: 10.1016/j.fuel.2014.11.021

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