CAREER: Combining Experiment and Theory for Improved H/N/O Kinetics

Ammonia is a chemical consisting of nitrogen and hydrogen, and it has been proposed for widespread use as a combustion fuel. To manage ammonia combustion efficiently and to avoid the formation of nitrogen oxides, a class of pollutants, the reaction rates for systems involving hydrogen, nitrogen, and/or oxygen (H/N/O) must be well understood. Despite decades of progress, discoveries are still being made, and surprising discrepancies persist in understanding H/N/O reaction rates. This project will combine experimental and theoretical techniques to address these discrepancies. The scientific knowledge gained will be more accurate rate constants for H/N/O reacting systems, especially at temperatures relevant to combustion. This new knowledge will improve the design of efficient engines, will help enable the use of ammonia as a fuel, and will help strengthen American energy security. The project is divided into three objectives. Objective I will obtain multi-species profiles of several species (NO, N2O, NO2, and H2O) during shock tube experiments designed to provide kinetic information (e.g., individual rate constants) using laser absorption spectroscopy. Objective II will calculate ab initio rate constants to support the measurements in Objective I and will quantify interfering side reactions that can be troublesome experimentally. Objective III will develop a novel laser absorption diagnostic for the intermediate species HONO, which has not been measured previously in a shock tube. Additionally, this project will involve design and construction of hands-on “pop-up” exhibits for children’s museums that will teach participants of all ages the basic principles of chemical kinetics. 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.