Laminar Burning Velocity Measurements in DIPK-An Advanced Biofuel

The biofuel and engine co-development framework was initiated at Sandia National Labs. Here, the synthetic biologists develop and engineer a new platform for drop-in fuel production from lignocellulosic biomass, using several endophytic fungi. Hence this process has the potential advantage that expensive pretreatment and fuel refining stages can be optimized thereby allowing scalability and cost reduction; two major considerations for widespread biofuel utilization. Large concentrations of ketones along with other volatile organic compounds were produced by fungi grown over switchgrass media. The combustion and emission properties of these new large ketones are poorly known. Therefore, fundamental measurements of representative molecules are needed to provide feedback on their desirability in advanced combustion engines (e.g., HCCI: homogeneous charge compression ignition engines) and their impact on emissions, as well as other combustion devices such as micro-combustors. 2,4-Dimethyl-3-pentanone, also known as diisopropyl ketone (DIPK), is a promising candidate biofuel for automotive applications produced by the fungal conversion process. Laminar burning velocity (LBV) is an important fundamental property of a fuel/air mixture and it depends on the composition, temperature, and pressure. Therefore, the knowledge of the dependence of the laminar burning velocity on above mentioned parameters can be used to design advanced engines as it can affect efficiency and heat release rates. We provide LBV measurements for DIPK, using the University of Central Florida (UCF) spherical flame chamber connected to a modified spark plug. Both pressure and direct flame visualization (shadowgraph) were utilized to ensure that the flame is spherical and stable (no cellular structure was observed within the flame) in order to provide reliable results with the constant volume approach. LBV measurements were also performed in iso-octane (C₈H₁₈), a relatively well characterized fuel, in order to validate our facility and measurement technique. The LBV results of C₈H₁₈/air and DIPK/air mixtures are compared with several oxygenated fuels in the literature and numerical values predicted by two chemical kinetic mechanisms.