CAREER: Multi-isotopologue absorption spectroscopy for hydrogen-carrier and nitrogen-based low-carbon energy

The next generation of fuels for the transportation and power generation sectors is expected to involve a mix of both traditional (carbon-based) and renewable or alternative fuels (hydrogen- or nitrogen-based). However, the reaction pathways of such future fuels and mixtures thereof are not well understood, preventing their deployment into the low-carbon, more fuel-efficient new generation of engines (including turbine, automotive, jet, and rocket engines). In this work, a novel laser diagnostic method, designed to measure multiple isotopes in isotopically-labeled fuel mixtures, is used to investigate fundamental chemical reaction pathways, including the formation of pollutants. Successful completion of the project will provide (1) a broadly applicable and novel measurement technique that will advance basic combustion and atmospheric science research and (2) new insights into the fundamental chemistry of ignition and pollutant formation in these new class of renewable fuel mixtures. Integrated education activities will impact students at multiple levels (middle school through graduate school) through open-source software development, integration of laboratory activities into The University of San Antonio’s growing aerospace curriculum, and targeted project-based outreach activities with middle school and high school students in San Antonio and the Lower Rio Grande Valley in Texas. The research objective of this project is to develop and explore applications of multi-isotopologue laser absorption spectroscopy for measurement, investigation, and modeling of kinetic pathways in high temperature reacting flows of next-generation and low-carbon hydrogen-carrier and nitrogen-based fuels. The technique is aimed at filling a gap in experimental high-temperature kinetics studies, which often cannot unambiguously track specific atoms in their reaction pathways from reactants to intermediates to products. The study will enable new classes of combustion studies for blended carbon / low-carbon fuel mixtures. It is hypothesized that the technique will provide new insights into reaction pathways for mixtures of varying fuel types (carbon-based, nitrogen-based, oxygenated) and functional groups. Paired with novel isotopically-labeled kinetic models and uncertainty-weighted sensitivity analyses, the framework provides a new means for reducing the required number and costs of experiments using isotopically-labeled chemicals. The novel high-pressure and high-temperature spectroscopy data and models generated in this project will also accelerate research in hypersonic flows, rocket propulsion, and remote sensing in planetary exploration, providing for broad applications of the research beyond combustion science for San Antonio and South Texas. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.