170221 20260407115449.0 doi 10.1016/j.enconman.2026.121350 sideral 148736 ART-2026-148736 eng Arroyo, Jorge (orcid)0000-0003-3157-6267 Experimental study on the combustion of methane-hydrogen mixtures in a pilot-scale furnace 2026 This study examines hydrogen as a low-emission alternative to natural gas in industrial furnace combustion, focusing on its well-known benefits of reducing carbon emissions and the technical challenges it presents. While decreasing carbon-based emissions with increased hydrogen content is well documented and serves as a primary motivation for its adoption, this work investigates the broader implications, particularly the increase in nitrogen oxide emissions, a significant contributor to air pollution, due to elevated combustion chamber temperatures. Experimental tests were conducted in a pilot-scale industrial furnace equipped with a burner operating at 42 kW, using pure methane, pure hydrogen, and various hydrogen-methane blends, over air-excess ratios ranging from 1.0 to 1.6. Temperature, heat transfer, pollutants, and radical-species emissions during combustion were measured using thermocouples, gas analyzers, spectroscopy, and optical imaging. Across the investigated air-excess range, carbon dioxide emissions decreased progressively by 10.5%, 18.8%, 45.3%, and 100% as the hydrogen content increased from 25% to 100% (relative to pure methane). In contrast, average nitrogen oxide emissions were maintained for a mixture of 25% of hydrogen, while they increased up to 28.5% for the blend with a 75% hydrogen content (relative to pure methane). Pure-hydrogen operation resulted in higher nitrogen oxide emissions, but these were partially mitigated by operating under lean conditions. Overall, hydrogen-enriched combustion supports decarbonization but can increase nitrogen oxide emissions, highlighting an important trade-off. Chemiluminescence analysis and visual diagnostics using RGB and Ultraviolet imaging further highlighted the qualitative differences between methane and hydrogen flames, with important implications for flame monitoring, real-time diagnosis of fuel composition, and safety in hydrogen-fired systems. These findings improve understanding of hydrogen’s role in industrial decarbonization and motivate the development of combustion strategies tailored to effectively control nitrogen oxide emissions. Access copy available to the general public Unrestricted info:eu-repo/grantAgreement/ES/MCIU/CER-20211002 info:eu-repo/semantics/openAccess by-nc https://creativecommons.org/licenses/by-nc/4.0/deed.es info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion Tovar-Lasheras, Fabiola Gil, Antonia Universidad de Zaragoza (orcid)0000-0002-0704-4685 5004 590 Universidad de Zaragoza Dpto. Ingeniería Mecánica Área Máquinas y Motores Térmi. 356 (2026), 121350 [10 pp.] Energy convers. manag. ENERGY CONVERSION AND MANAGEMENT 0196-8904 10039829 http://zaguan.unizar.es/record/170221/files/texto_completo.pdf Versión publicada 2506428 http://zaguan.unizar.es/record/170221/files/texto_completo.jpg?subformat=icon icon Versión publicada oai:zaguan.unizar.es:170221 articulos driver 2026-03-26-14:31:59 ARTICLE