This research project is aimed at determining the pollutant formation chemistry of algae-derived biofuels, which have potential to be high-yield, efficiently produced, renewable fuels. In combustion of biodiesel and straight vegetable oil (SVO), formation of pollutants such as NOx and soot has been linked to the chemical structure of the triglycerides present in the feedstock. Pioneering work is needed to characterize the combustion chemistry and pollutant formation chemistry of algae-derived biodiesel and SVO, which have far different fatty-acid compositions than typical vegetable or animal-fat feedstocks. Research activities are focused on homogeneous-compression ignition and partially premixed droplet ignition of algae-derived SVO, fatty acid methyl esters (FAME) and renewable diesel. Combustion and pollutant formation studies are performed using a rapid compression machine (RCM). These experiments enable instantaneous measurement of gas-phase intermediates and pollutants such as NO, NO2, CO, CO2, formaldehyde, HCN and soot precursors, which can be compared against chemical kinetic models currently under development. In a second configuration, ignition of a monodisperse liquid droplet stream in a high temperature oxidizing environment is used as an analog to the heterogeneous diesel ignition and combustion process. This configuration allows quantitative, temporal and spatial measurements of NO, OH and CH in the vicinity of an igniting algae-based fuel droplet using planar laser-induced fluorescence (PLIF), along with soot volume-fraction measurements using laser-induced incandescence (LII). Droplet data are then compared against a transient, spherically symmetric, chemically reacting flow model. Performing these combinations of experiments and modeling on algae-derived fuels will provide valuable insight into both the rapid premixed-combustion phase, where prompt NOx and soot precursors are formed, and the transition to non-premixed combustion, where thermal NOx and soot are formed. Anthropogenic climate change is a civilization-scale challenge. While there is no single solution, renewable fuels such as biodiesel and SVO can play a significant role in mitigating greenhouse gas emissions. This research provides opportunities for undergraduate research, undergraduate design, and graduate research aimed at educating the new generation of engineers who must provide creative energy solutions that effectively address climate change.
