Plasma-Assisted Combustion in Automobile Engines Using Semiconductor-Oscillated Microwave Discharge Igniters

Abstract

Plasma-assisted ignition and combustion, and microwave-enhancement of exhaust gas catalytic conversion in automobiles are presented in this chapter. Both processes within and outside of the engine are implemented using a 2.45 GHz semiconductor-oscillated microwave (MW) source or device. The latent potential of fast catalyst light-off was evaluated by applying MW heat to carbon microcoil (CMC) located at the core of a converter. CMC material has high heat absorption efficiency, and is capable of localised and selective heating. The absorption efficiency was approximately 60% with a CMC mass fraction of 10 wt%. Plasma-assisted combustion was implemented by a microwave discharge igniter (MDI) developed by Imagineering, Inc., Japan. The MDI improves combustion performance and enhances lean burn limit due to its ability to generate non-equilibrium, non-thermal plasmas. The oscillator for the MDI has an auto-adjusting capability that ensures the attainment of new resonant frequencies despite the negative effects of material erosion. This allowed continued production of radical species for improving combustion performance. Test runs performed on a commercially available automobile engine demonstrated that the MDI outperforms conventional spark ignition systems.