Optical engine characterization of reference and novel fuels using a small-volume fuel system

Global climate change drives research and implementation of low-carbon fuels. Engine combustion imaging offers insights to fuel performance and can be conducted early in the fuel development cycle due to relatively low consumption rates compared to those required for steady-state emissions testing. A flexible fueling system is used, implementing a hydraulic media separator for direct injection of up to 260 mL alternative fuel samples at pressures up to 1200 bar into a 2.0L, single-cylinder, optically accessible diesel engine. Optical engine studies provide understanding of injection spray phenomena, ignition delays, heat release rates, and soot propensity with qualitative analysis of reaction zone structure and propagation using high-speed imaging of natural luminosity and OH*-chemiluminescence. A local, three-colour pyrometry probe enables measurement of in-cylinder soot concentration and temperature. Two operating conditions were chosen to investigate various phenomena. The first operating condition is a low load single fuel injection that allows for consideration of injection and ignition behaviour in the mixing controlled combustion regime. The second operating condition uses a pilot and main fuel injection and is representative of a medium load condition using modern diesel injection strategies. Six fuels are characterized: diesel and n-heptane, reference fuels; canola and soybean methyl ester, commercial biodiesels; and graphene-oxide (GO) doped diesel and a blend of upgraded bio-oil (UBO) from fast pyrolysis of pine biomass with diesel, novel fuels. Fuel properties were measured using ASTM standards for energy content, viscosity, elemental analysis, and moisture content. The UBO diesel blend demonstrates a 7% reduction in ignition delay and 25% reduction in in-cylinder soot concentration relative to neat diesel. The addition of 10ppm GO to diesel did not affect fuel performance.Applied Science, Faculty ofGraduate and Postdoctoral StudiesGraduat