60167 - Ozone Production With Plasma Discharge: Comparisons Between Activated Air and Activated Fuel/air Mixture 

Plasma assisted combustion (PAC) is one of the most prominent and effective technology in order to enhances the efficiency of combustors, increases flame stabilization, improves low temperature oxidation, extends limits of lean blow out and reduces significant amount of nitrogen oxides (NO_x). Plasma discharge has great potential to improve ignition and combustion by three ways via thermal, kinetic and transport. This study focused on the comparative analysis about the production of ozone and activated radicals in presence of nanopulsed plasma discharge on air and on fuel/air mixture to investigated its effect on combustion enhancement. The analysis is based on the kinetic modeling of air and methane – air plasma discharge with different E_N values (100Td, 150 Td and 200Td) and repetition rates (100 Hz, 1000Hz and 10000Hz). Previously, many numerical and experimental studies on the air and methane – air plasma were performed separately. But only few experimental studies showed the comparative investigation on the production of active particles. However, there was no any detailed and comparative numerical kinetic model was developed in order to analyze the comparative effects of plasma discharge of air and methane – air mixture. In this paper, two numerical tools Plasma Kinetic Solver (ZDPlasKin) and Chemical Kinetic Solver (CHEMKIN) are used. Therefore, a detailed chemical kinetic mechanism was developed including the dissociative and recombination reactions, electronically and vibrationally excited species, relaxation reactions and charged transfer reactions, three body recombination reactions concluded from the past mechanisms where available. Validation of air and methane – air mechanisms were performed with experimental data. It was observed that the kinetic models of both air and methane – air mixture provides good agreement with experimental data of O atom generation and decay process. For these models, ZDPlasKin integrated with Boltzmann equation solver (BOLSIG+) for calculating the time evolution of species. ZDPlasKin results were incorporated in CHEMKIN in order to analyze combustion process such as flame speed and ignition characteristics. It was found that concentration of O atom and O₃ in air is higher than the methane - air mixture this was due to their reactions with methane species in order to produce intermediate radicals. Besides this, it was also observed that with the increase of number of pulses and E_N values, the peak concentration of active particles of air were significantly increased in comparison with methane – air mixture.