XII-13, 1 The Effect of Hydrogen Enrichment on CH4-Air Combustion in

Lean premixed combustion is a solution to reduce flame temperatures and pollutant emissions, especially NOx. This will strongly use for the future internal combustion engines. But the main drawbacks are the decrease of the global burning speed and the misfire. The aim of this study is first to verify or not is the addition of an amount of hydrogen can extend the lean operating limit of air-methane combustion with dilution and maintain the flame velocity at the same value without dilution. For that, the effect of adding hydrogen to methane-air-N2 mixtures has been investigated. The laminar burning velocity for different N2 dilution amounts (from 0- 30%) and for different hydrogen additions (from 0 to 30%) has been determined at atmospheric pressure and ambient temperature. Experiments were carried out in a stainless steel combustion chamber. Flame speeds were determined by using classical shadowgraph technique. The images were recorded by a high-speed camera. A computational method based on a detailed chemical kinetic scheme (GRIMECH 3.0) was used to provide the expansion factor and to calculate the laminar burning velocities for comparison with experimental results. As hoped, by increasing hydrogen percentage in the mixture leads to an increase of the laminar burning velocity, but the absolute increasing due to the hydrogen addition of the laminar burning velocity decreases as the dilution with N2 become higher