Species Measurements of Non-Equilibrium Plasma-Assisted Combustion Using QCL Absorption Spectroscopy

Abstract

Plasma assisted combustion is a promising method towards enhancing fuel efficiency and reducing emission for combustion engines. Plasma dramatically modifies the combustion processes in that it changes fuel oxidation rates, and introduces new reaction pathways because of its capability of fast electron impact excitation and dissociation of molecules in the fuel/oxidizer mixture. The experiment analyzed plasma assisted combustion of CH4/O2/Ar flows through a Herriott cell designed for in-situ measurements to be performed during the plasma discharges. These measurements of reaction intermediates, final products and temperature of the combustion process were taken using a Quantum Cascade Laser and were used to create and validate a kinetic model to determine radical and excited species reaction processes and rates. The focus of this research discusses methodology of processing the experimental data and comparing it to the kinetic model. The processed data was also used to find suitable initial conditions of plasma discharge frequency, plasma intensity, and plasma pulse number for obtaining maximum combustion reaction products such as H2O, along with ideal residence time and temperature for combustion. Limitations of the work are identified along with introducing insight for future research in this field.