Revving up future mobility: hybridization, alternative fuels and the renaissance of the 2-stroke engine cycle

This PhD thesis explores advancements in internal combustion engines (ICEs) through hybridization, alternative fuels, and two-stroke (2S) engine design updates to reduce emissions and improve efficiency. Key research areas include hybrid powertrains for motorcycles and aircraft, ethanol-based biofuels for small to medium-duty engines, and hydrogen deployment in two- and four-stroke engines. The study examines 2S engine architectures, comparing scavenging methodologies in opposed-piston uniflow, conventional loop, and reverse loop designs. It also investigates hybrid-electric applications in motorcycles and ultralight aircraft, assessing efficiency gains. Additionally, ethanol-based biofuels are tested in opposed-piston and 4-stroke engines with minimal modifications. Results show that optimized 2S engines running on hydrogen or biofuels offer high efficiency and low emissions. Hydrogen-fueled opposed-piston engines demonstrate near-zero NOx emissions and high thermal efficiency, making them suitable for power generation and high-power-density applications. This research highlights ICEs' continued relevance in a sustainable energy landscape, advocating for a balanced approach integrating ICE advancements, sustainable fuels, electrification, and fuel cells. Through computational fluid dynamics (CFD) simulations and experimental validation, it contributes to developing cleaner, high-performance ICE technologies.