Optical investigation of mixing-controlled combustion using a novel transgenic plant oil

Abstract

Fuels derived from plant oils hold promise as alternatives to petroleum-derived fuels due to their renewable production strategies, and potential to reduce net carbon emissions. Due to their high viscosity and cloud point, and low volatility however, direct use of plant oils in engines, without transesterification, poses a challenge. Recently, genetic modification has been used to alter plant lipid biosynthesis, producing novel oils that may overcome some of these challenges. In this study, 3-acetyl-1, 2-diacyl-sn-glycerol (Ac-TAG), extracted from a strain of transgenic Camelina Sativa, was studied in an optically-accessible diesel engine. Simultaneous high-speed shadowgraphy and OH* chemiluminescence imaging data were collected to obtain measurements of jet development, liquid penetration, ignition location, and flame liftoff length. A conventional diesel fuel and untransformed neat camelina oil were run at the same conditions as the Ac-TAG fuel for comparison. Even though the Ac-TAG fuel had significantly lower viscosity than the neat camelina oil, no significant differences were observed between Ac-TAG and neat camelina oil in any of the quantities studied. Relative to diesel, the biofuels had greater liquid penetration, shorter liftoff lengths and ignition delay, and consistently ignited farther upstream.