64760 2025 eng 1 7 41 article Elsevier Inc. 1 -- -- -- The paper presents the results of an experimental and reaction kinetic investigation of hydrogen ignition at different pressures in a closed vessel, highlighting its non-linear behavior and the effects of radical wall termination. The reaction kinetic simulation predicts the three characteristic ignition limits of hydrogen caused by radical and thermal auto-ignition and is in close agreement with the experimental measurements. The first ignition limit is determined by the chain branching reaction H+O_2→O+ OH. This limit shows strong sensitivity towards the wall termination of O, H and OH radicals. The second ignition limit is influenced by the wall termination of O, H, OH, HO2 and H2O2 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 strong sensitivity towards wall termination of HO₂ and H₂O₂ radicals. Increasing the radical wall termination rate by increasing the sticking coefficient of the radicals at the wall or the surface-to-volume-ratio leads to an increase of the auto-ignition temperature at the same pressure. The introduction of radical wall termination reactions improved the prediction of ignition limits and highlighted the profound effect of the autoclave wall and vessel size on the hydrogen ignition behavior. Proceedings of the Combustion Institute 1540-7489 10.1016/j.proci.2025.105980 urn:nbn:de:kobv:b43-647609 true journal-article https://www.elsevier.com/tdm/userlicense/1.0/ crossref PersonAuthorFirstName_1,PersonAuthorLastName_1,PersonAuthorFirstName_2,PersonAuthorLastName_2,PersonAuthorFirstName_3,PersonAuthorLastName_3,PersonAuthorIdentifierOrcid_3,PersonAuthorFirstName_4,PersonAuthorLastName_4,PublisherName,TitleMain_1,Language,TitleParent_1,ArticleNumber,Volume,PublishedYear,IdentifierIssn,Enrichmentlocal_crossrefLicence doi-import 01.12.2025 Creative Commons - CC BY - Namensnennung 4.0 International Hayat El Harrab Enis Askar T. Franken F. Mauss eng uncontrolled Radical Wall Termination Reaction eng uncontrolled Hydrogen eng uncontrolled Auto-ignition Temperature eng uncontrolled Ignition Limit Angewandte Physik 2 Prozess- und Anlagensicherheit 2.1 Sicherheit von Energieträgern Energie Verlagsliteratur Datei für die Öffentlichkeit verfügbar ("Open Access") Wissenschaftliche Artikel der BAM Wasserstoff Bundesanstalt für Materialforschung und -prüfung (BAM) https://opus4.kobv.de/opus4-bam/files/64760/1-s2.0-S1540748925001944-main.pdf