Degree
Doctor of Philosophy (PhD)
Department
Department of Mechanical and Industrial Engineering
Document Type
Dissertation
Abstract
This dissertation focuses on two main studies: chemical kinetic modal analysis and micro-liter fuel testing at elevated pressures. The first study introduces a novel chemical mode analysis methodology that advances beyond traditional approaches like Computational Singular Perturbation (CSP) and Chemical Explosive Mode Analysis (CEMA). This enhanced framework enables identification, sorting, and temporal tracking of individual reaction modes, revealing crucial insights into micro-combustion kinetics. Initial application to hydrogen-air ignition demonstrates that dominant modes may not drive kinetics near the lower flammability limits due to strong modal coupling between competing processes. Hence, the dominant mode might not be sufficient to fully understand the chemical kinetic dynamics at such conditions, unlike what conventional approaches suggest.
Although the cooperative fuel research (CFR) engine remains the industry standard for measuring octane numbers (a measure of fuel reactivity), its high costs and large fuel requirements limit its practicality for evaluating advanced fuels like biofuels. To address this limitation, we developed a novel micro-combustor as an alternative to the CFR engine. Previous research established that the velocity of transition between the flame regimes is correlated with fuel reactivity, but these studies were carried out primarily at low and intermediate pressures (≤ 10 bar), while CFR engines operate at 15 bar. Our microcombustor test rig operates at these elevated pressures while requiring only microliter- scale fuel samples and featuring no moving parts, offering significant cost and efficiency advantages over traditional CFR testing. Using this new instrument, we investigated the combustion characteristics of ethane and ethylene-air mixtures under varying pressure and nitrogen dilution conditions. The results showed a significant dependence on flame propagation on dilution levels and equivalence ratios. This work establishes the microcombustor as a viable alternative to the CFR engine for fuel reactivity assessment, providing comparable insights while dramatically reducing required sample volumes and testing costs.
Date
4-3-2025
Recommended Citation
Akinpelu, David A., "COMBUSTION CHARACTERISTICS IN A HEATED MICRO-CHANNEL AT ELEVATED PRESSURES" (2025). LSU Doctoral Dissertations. 6764.
https://repository.lsu.edu/gradschool_dissertations/6764
Committee Chair
Dr. Ingmar Schoegl