Mechanical Engineering Ph.D. Defense

Abstract

Addressing the complex challenges posed by greenhouse gas emissions and global warming necessitates a multifaceted approach encompassing renewable energy, fuel transition, and enhanced efficiency measures. The sustainability of existing infrastructure mandates strategies that not only curtail carbon footprints but also achieve near-zero levels of detrimental pollutants, such as particulate matter, soot, nitric oxides (NO_x), and unburnt hydrocarbons. A promising avenue toward achieving these ambitious targets involves the advancement and adoption of octane-enhanced gasoline blends. Alcohols, readily accessible at the commercial scale, are prominently emerging as viable contenders and progressively being positioned as suitable additives for gasoline fuels, reaping a host of advantageous outcomes in the process. This shift towards alcohol-enriched gasolines aligns with global efforts to transition towards a low-carbon, eco-friendly future in the transportation industry.

This dissertation focuses on measuring ignition delay times, a fundamental indicator of fuel reactivity, for a wide range of octane-enhanced fuels and e-fuels, suitable for advanced combustion engines. The research began with a baseline gasoline containing 10% (by vol.) ethanol. This initial work aimed to establish a foundational understanding of the effect of ethanol blending on the autoignition characteristics of gasolines. As the investigation progressed, the scope broadened to investigate the interaction of this baseline gasoline with increased ethanol blending, exhaust gas recirculation, and NO_x addition, showcasing their impacts on gasoline reactivity. Thereafter, autoignition characteristics of drop-in e-gasolines, with varying properties, were examined. Such e-gasolines are designed to replace or supplement traditional gasoline while maintaining compatibility with the existing infrastructure. This investigation delved into enhancing e-gasolines octane rating by blending with methanol, characterized by a complete absence of C–C bonds, and prenol, characterized by a C═C double bond. Experimental studies were accompanied by chemical kinetic modelling and reactivity analyses. A compact gasoline surrogate model, valid for a wide range of octane-enhanced gasolines, was assembled in a systematic fashion, starting with a comprehensive chemical kinetic model and supplementing it with appropriate sub-mechanisms from the literature with minor adjustments. Experimental data, chemical kinetic models and the analyses presented in this dissertation provide a benchmark for efficient integration of octane-enhanced gasolines in advanced combustion engines.

Bio

Khalid is a Ph.D. candidate in the Mechanical Engineering program at the Clean Combustion Research Center (CCRC) within the PSE division. He conducts his research in the Chemical Kinetics and Laser Sensors Laboratory, supervised by Prof. Aamir Farooq. Khalid's academic background includes a B.Sc. degree from Taibah University in Saudi Arabia, where he graduated with honors. He then pursued his M.Sc. degree at Northeastern University in Boston, USA. Khalid's research interests include: autoignition characteristics of real gasoline / e-gasoline fuels, and their interactions with additives such as EGR, NO_x, and alcohol fuels, and kinetic model development. He utilizes high-pressure shock tube and rapid compression machine, which are experimental setups commonly used in the field of kinetic research.