Impacts of Hydrogen and Carbon Dioxide Addition on Knock Resistance of Methane-based Fuels

Abstract

Impacts of hydrogen and carbon dioxide addition on knock resistance of methane-based fuels were investigated with a view to rationalize the improving effect of steam reforming of natural gas on methane number. Addition of hydrogen and carbon dioxide with a same volumetric amount to methane showed no impact on the knock resistance of fuels regardless of a volumetric proportion of methane. This is due to the fact that shortening effect of hydrogen on the ignition delay time and decreasing effect of carbon dioxide on specific heat ratio, which suppresses temperature increase in the unburned gas temperature, cancel out each other.