Numerical Study on Ultra-micro Combustor with Considering Radical Quenching on the Wall

Abstract

In recent years, electrical devices like cell phone and laptop PC have been downsized. So, there is high demand to develop smaller and lighter electrical generator than it is, and many researchers have studied ultra-micro generators. Ultra-micro gas turbine, that is one of ultra-micro generators, is expected to have the energy density of several ten times higher than lithium ion battery. But, the smaller combustor is, the stronger the effect of the wall is. Therefore, thermal quenching and radical quenching through the wall cause combustion more unstable in ultra-micro combustor. Most of researches consider thermal quenching effect, while they ignore radical quenching effect. Moreover, a combustor is too small to measure combustion condition experimentally. This paper describes the result obtained by the numerical simulation for H₂-Air premixed gas combustion considering radical quenching in a simple parallel plate channel and a practical ultra-micro combustor. The numerical model has elementary reaction kinetics considering adsorption and desorption reaction on wall. The details of combustion characteristics, such as temperature, mole fractions, surface coverage, reaction rate and etc, are obtained. The effects of radical quenching are especially examined by comparing with combustor considering surface reactions and one not considering surface reactions. Through these examinations, the effects of radical and heat quenching and radical quenching mechanisms are made clear.