- The paper presents the results of the experimental and reaction kinetic investigation of hydrogen ignition at different pressures, highlighting its non-linear behaviour and effects of radical wall termination. The reaction kinetic simulation predicts the three characteristic ignition limits caused by radical and thermal auto-ignition and is in close agreement with the experimental measurements. The introduction of radical wall termination in the reaction mechanism allowed us to investigate the effect of the autoclave wall and vessel size on the hydrogen ignition behaviour. The first ignition limit is determined by the chain initiation reaction H_2+O_2→2 OH and shows a strong sensitivity towards wall termination of O, H and OH radicals. The third ignition limit is dominated by the reaction paths HO_2+HO_2→H_2 O_2+O_2 and H_2 O_2+M→2 OH+M which is why it shows a strong sensitivity towards wall termination of HO₂ and H₂O₂ radicals. The second ignition limit is influenced by the wallThe paper presents the results of the experimental and reaction kinetic investigation of hydrogen ignition at different pressures, highlighting its non-linear behaviour and effects of radical wall termination. The reaction kinetic simulation predicts the three characteristic ignition limits caused by radical and thermal auto-ignition and is in close agreement with the experimental measurements. The introduction of radical wall termination in the reaction mechanism allowed us to investigate the effect of the autoclave wall and vessel size on the hydrogen ignition behaviour. The first ignition limit is determined by the chain initiation reaction H_2+O_2→2 OH and shows a strong sensitivity towards wall termination of O, H and OH radicals. The third ignition limit is dominated by the reaction paths HO_2+HO_2→H_2 O_2+O_2 and H_2 O_2+M→2 OH+M which is why it shows a strong sensitivity towards wall termination of HO₂ and H₂O₂ radicals. The second ignition limit is influenced by the wall termination of O, H, OH, HO2 and H2O2 radicals. Increasing the radical wall termination rate by increasing the adsorption rate of the radicals at the wall leads to an increase of the auto-ignition temperature at the same pressure.…

