Investigation on the Effects of Emerging Alternative Fuels and Additives on Compression Ignition Engine Performance, Combustion and Emissions

Internal combustion engines play a significant role in present society. The use of internal combustion engines, however, has drawbacks mostly in the areas of fuel security and pollutant emissions. Renewable fuels are means by which both drawbacks may be resolved. As renewable fuels can be produced through different means and from different resources with quite different properties, there is a need to understand the effects on their applications in internal combustion engines. This dissertation focuses on contributing to the use of renewable fuels in internal combustion engines by testing and understanding the effects of emerging alternative fuels and renewable additives in compression-ignition engines.;The works discussed here were performed in a compression-ignition engine. In the first set of experiment, the performance, combustion and emissions from an engine running second generation biofuels, also called renewable diesel, were investigated. From this experiment, it was determined that diesel engine performance did not change much when run on renewable diesel. Renewable diesel had longer ignition delays and resulted in significantly lower engine emissions including soot with the exception of hydrocarbon emissions when compared to conventional diesel fuel.;Another emerging second generation biofuel, called biomass to liquid fuel (BTL), was compared to diesel fuel and a first generation biodiesel. It was determined from the result of this experiment that running a diesel engine on BTL improved fuel economy and thermal efficiency. The mechanical efficiency of the engine running on BTL was found to be similar to that of diesel and biodiesel as engine load increased. BTL was also observed to have a shorter ignition delay when compared to conventional diesel but longer ignition delay when compared to biodiesel. Overall, diesel engine running on BTL had lower engine emissions with the exception of NOx when compared to diesel.;The third experiment is a slight deviation from the concept of renewable fuels. In this experiment, fuel in water emulsion using a renewable surfactant (carboxymethylated Kraft Lignin) was used in the engine. Three different fuels, including diesel, biodiesel and jet fuel, were used in making the fuel emulsions. The fuel emulsions generally resulted in improved engine performance but poorer fuel consumption. Considering fuel content only in the emulsions, fuel economy became better than the base fuels with the exception of jet fuel. Fuel emulsions had longer ignition delays than their base fuel counter parts. Engine emissions of fuel emulsions depend on engine operating conditions and the type of base fuel.;The final study performed in this dissertation focused on the use of renewable fuel additives. These additives, catechol, vanillin, guaiacol, vanillin ester, catechol ester were obtained from the pyrolysis of lignin, a renewable compound. It was found from this study that when dissolved in a solvent and added in small quantities to diesel fuel as an additive, most of the compounds resulted in a better engine performance. With the exception of vanillin ester, the compounds mostly had little to no impact on the combustion profile of the engine but still resulted in much lower emissions when compared to diesel.;All these results have been positive especially with regards to emissions reduction with the additional bonus of been from renewable sources. It is clear then that fuels and fuel additives from renewable sources have the potential for improving the internal combustion engine with better combustion and lower emissions.