Jihyung Yoo

Combustion stability is an important consideration for many energy systems because of its impact on performance and efficiency. Flame dynamics that govern combustion stability are often complex and difficult to resolve, particularly from experimental data. However, recent advances in postprocessing techniques, such as dynamic mode decomposition (DMD), have partially enabled flame dynamic analysis. This study aims to provide a comprehensive measure of combustion stability through a detailed inves

Exhaust gas recirculation (EGR) in internal combustion engines is an effective method of reducing NOx emissions while improving efficiency. However, insufficient mixing between fresh air and exhaust gas can lead to cycle-to-cycle and cylinder-to-cylinder non-uniform charge gas mixtures of a multi-cylinder engine, which can in turn reduce engine performance and efficiency. A sensor packaged into a compact probe was designed, built and applied to measure spatiotemporal EGR distributions in the int

Development of a stable and efficient small-scale combustor architecture with comparable performance emission characteristics to large-scale burners is presented. Furthermore, the proposed architecture reduced susceptibility to extinction and maintained high combustion efficiency and low emission levels under ultralean operating conditions for a wide range of combustion power outputs. Prototype burner arrays were additively manufactured and demonstrated with methane/air flames. The burner sustai

Thermal performance of an electric vehicle (EV) battery module with an integrated cooling insert was numerically analyzed using computational fluid dynamics (CFD). Twelve NCM prismatic cells were packaged into a module where each cell was physically isolated from its neighboring cells by the cooling insert, designed to enhance the module’s thermal performance. The battery cells and the cooling insert were attached to a thermal interface material (TIM) and a cooling plate with integrated liquid c

Simultaneous measurements of light hydrocarbon species based on near-infrared (near-IR) supercontinuum laser absorption spectroscopy (SCLAS) are demonstrated. SCLAS is a broadband absorption diagnostic technique that provides significant advantages over existing absorption diagnostic techniques. Coupled with a fast spectrum analysis strategy, accurate measurements of multiple hydrocarbon concentrations can be made concurrently. Methane (CH4), acetylene (C2H2), ethylene (C2H4), and their mixtures

The need for more environmentally friendly and efficient energy conversion is of paramount importance in developing and designing next-generation internal combustion (IC) engines for transportation applications. One effective solution to reducing emissions of mono-nitrogen oxides (NOx) is exhaust gas recirculation (EGR), which has been widely implemented in modern vehicles. However, cylinder-to-cylinder and cycle-to-cycle variations in the charge-gas uniformity can be a major barrier to optimum

Minute concentration measurements of simple hydrocarbon gases are demonstrated using near-infrared supercontinuum laser absorption spectroscopy. Absorption-based gas sensors, particularly when combined with optical fiber components, can significantly enhance diagnostic capabilities to unprecedented levels. However, these diagnostic techniques are subject to limitations under certain gas sensing applications where interference and harsh conditions dominate. Supercontinuum laser absorption spectro