{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,16]],"date-time":"2026-04-16T01:08:56Z","timestamp":1776301736296,"version":"3.50.1"},"reference-count":61,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2025,6,2]],"date-time":"2025-06-02T00:00:00Z","timestamp":1748822400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia (FCT)"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Energies"],"abstract":"<jats:p>Ammonia (NH3) and hydrogen (H2) are considered promising fuels for the power sector\u2019s decarbonization. Their combustion is capable of producing energy with zero direct CO2 emissions, and ammonia can act as a stable energy H2 carrier. This study numerically investigates the design and implementation of staged combustion of a mixture of NH3\/H2 by means of CFD simulations. The investigation employed the single-phase flow RANS governing equations and the eddy dissipation concept (EDC) combustion model, with the incorporation of a detailed kinetic mechanism. The combustion chamber operates under the RQL (rich\u2013quench\u2013lean) combustion regime. The first stage operates under rich conditions, firing mixtures of ammonia in air, enriched by hydrogen (H2) to enhance combustion properties in a swirl and bluff-body stabilized burner. The secondary stage injects additional air and hydrogen to mitigate unburnt ammonia and NOx emissions. Simulations of the first stage were performed for a thermal input ranging from 4 kW to 8 kW and flames with an equivalence ratio of 1.2. In the second stage, additional hydrogen is injected with a thermal input of either 1 kW or 2 KW, and air is added to adjust the global equivalence ratio to 0.6.<\/jats:p>","DOI":"10.3390\/en18112919","type":"journal-article","created":{"date-parts":[[2025,6,2]],"date-time":"2025-06-02T08:34:13Z","timestamp":1748853253000},"page":"2919","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["CFD-Assisted Design of an NH3\/H2 Combustion Chamber Based on the Rich\u2013Quench\u2013Lean Concept"],"prefix":"10.3390","volume":"18","author":[{"given":"Gon\u00e7alo","family":"Pacheco","sequence":"first","affiliation":[{"name":"IDMEC, Instituto Superior T\u00e9cnico, Universidade de Lisboa, 1649-004 Lisboa, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6605-2706","authenticated-orcid":false,"given":"Jos\u00e9","family":"Chaves","sequence":"additional","affiliation":[{"name":"IDMEC, Instituto Superior T\u00e9cnico, Universidade de Lisboa, 1649-004 Lisboa, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9817-2334","authenticated-orcid":false,"given":"Miguel","family":"Mendes","sequence":"additional","affiliation":[{"name":"IDMEC, Instituto Superior T\u00e9cnico, Universidade de Lisboa, 1649-004 Lisboa, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0280-805X","authenticated-orcid":false,"given":"Pedro","family":"Coelho","sequence":"additional","affiliation":[{"name":"IDMEC, Instituto Superior T\u00e9cnico, Universidade de Lisboa, 1649-004 Lisboa, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2025,6,2]]},"reference":[{"key":"ref_1","unstructured":"United Nations (2015). Paris Agreement. United Nations Framework Convention on Climate Change, United Nations."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Saygin, D., Blanco, H., Boshell, F., Cordonnier, J., Rouwenhorst, K., Lathwal, P., and Gielen, D. (2023). Ammonia Production from Clean Hydrogen and the Implications for Global Natural Gas Demand. Sustainability, 15.","DOI":"10.3390\/su15021623"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"107380","DOI":"10.1016\/j.fuproc.2022.107380","article-title":"Ammonia as a Green Energy Carrier: Electrochemical Synthesis and Direct Ammonia Fuel Cell\u2014A Comprehensive Review","volume":"235","author":"Wang","year":"2022","journal-title":"Fuel Process. Technol."},{"key":"ref_4","unstructured":"IEA (2021). Ammonia Technology Roadmap Towards More Sustainable Nitrogen Fertiliser Production, IEA."},{"key":"ref_5","unstructured":"Cardoso, J.P. (2024). Ammonia as a Decarbonization Tool for Low Carbon Fuel Applications and Stationary Power Generation. [Ph.D. Thesis, Instituto Superior T\u00e9cnico]."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"109","DOI":"10.1016\/j.proci.2018.09.029","article-title":"Science and Technology of Ammonia Combustion","volume":"37","author":"Kobayashi","year":"2019","journal-title":"Proc. Combust. Inst."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"13","DOI":"10.1007\/s43979-024-00088-6","article-title":"Ammonia Combustion and Emissions in Practical Applications: A Review","volume":"3","author":"Alnajideen","year":"2024","journal-title":"Carbon Neutrality"},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Pacheco, G., Pereira, J., Mendes, M., and Coelho, P. (2024). Investigation of a Fuel-Flexible Diffusion Swirl Burner Fired with NH3 and Natural Gas Mixtures. Energies, 17.","DOI":"10.3390\/en17174206"},{"key":"ref_9","unstructured":"Mission Possible Partnership (2025, February 12). Making Net-Zero Ammonia Possible. Available online: https:\/\/www.energy-transitions.org\/publications\/making-net-zero-ammonia-possible\/."},{"key":"ref_10","unstructured":"Mission possible Partnership (2025, January 19). MPP Global Project Tracker. Available online: https:\/\/tracker.missionpossiblepartnership.org\/mpp-global-projects-map\/."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"822","DOI":"10.1016\/j.rser.2016.01.120","article-title":"Ammonia-Fed Fuel Cells: A Comprehensive Review","volume":"60","author":"Afif","year":"2016","journal-title":"Renew. Sustain. Energy Rev."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"169708","DOI":"10.1016\/j.scitotenv.2023.169708","article-title":"The Application Prospect and Challenge of the Alternative Methanol Fuel in the Internal Combustion Engine","volume":"913","author":"Zhou","year":"2024","journal-title":"Sci. Total Environ."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Lan, R., and Tao, S. (2014). Ammonia as a Suitable Fuel for Fuel Cells. Front. Energy Res., 2.","DOI":"10.3389\/fenrg.2014.00035"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"3513","DOI":"10.1080\/00102202.2023.2239462","article-title":"Modeling of Ammonia MILD Combustion in Systems with Internal Recirculation","volume":"195","author":"Giuntini","year":"2023","journal-title":"Combust. Sci. Technol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"2514","DOI":"10.1080\/00102202.2020.1748018","article-title":"Combustion and Emission Characteristics of Ammonia under Conditions Relevant to Modern Gas Turbines","volume":"193","author":"Rocha","year":"2021","journal-title":"Combust. Sci. Technol."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"185","DOI":"10.1016\/j.combustflame.2017.09.002","article-title":"Experimental and Numerical Study of the Laminar Burning Velocity of CH4\u2013NH3\u2013Air Premixed Flames","volume":"187","author":"Okafor","year":"2018","journal-title":"Combust Flame"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"3351","DOI":"10.1016\/j.proci.2016.07.088","article-title":"Performances and Emission Characteristics of NH3-Air and NH3-CH4-Air Combustion Gas-Turbine Power Generations","volume":"36","author":"Kurata","year":"2017","journal-title":"Proc. Combust. Inst."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"105494","DOI":"10.1016\/j.proci.2024.105494","article-title":"Ammonia Blends for Gas-Turbines: Preliminary Test and CFD-CRN Modelling","volume":"40","author":"Romano","year":"2024","journal-title":"Proc. Combust. Inst."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"7201","DOI":"10.1021\/acs.energyfuels.0c03872","article-title":"Experimental and Kinetic Investigation of Stoichiometric to Rich NH3\/H2\/Air Flames in a Swirl and Bluff-Body Stabilized Burner","volume":"35","author":"Pacheco","year":"2021","journal-title":"Energy Fuels"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"116059","DOI":"10.1016\/j.fuel.2019.116059","article-title":"Chemical Mechanism Development and Reduction for Combustion of NH3\/H2\/CH4 Mixtures","volume":"257","author":"Li","year":"2019","journal-title":"Fuel"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"144577","DOI":"10.1016\/j.cej.2023.144577","article-title":"Low- and Intermediate-Temperature Ammonia\/Hydrogen Oxidation in a Flow Reactor: Experiments and a Wide-Range Kinetic Modeling","volume":"471","author":"Stagni","year":"2023","journal-title":"Chem. Eng. J."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"162","DOI":"10.1016\/j.combustflame.2019.03.008","article-title":"Measurement and Modelling of the Laminar Burning Velocity of Methane-Ammonia-Air Flames at High Pressures Using a Reduced Reaction Mechanism","volume":"204","author":"Okafor","year":"2019","journal-title":"Combust Flame"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"129389","DOI":"10.1016\/j.fuel.2023.129389","article-title":"Development of a Reduced Combustion Model for Ammonia\/Hydrogen Combustion","volume":"354","author":"Ren","year":"2023","journal-title":"Fuel"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.ijhydene.2024.09.071","article-title":"Modelling and Development of Ammonia-Air Non-Premixed Low NOX Combustor in a Micro Gas Turbine: A CFD Analysis","volume":"88","author":"Fatehi","year":"2024","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"091022","DOI":"10.1115\/1.4064807","article-title":"Modeling Ammonia-Hydrogen-Air Combustion and Emission Characteristics of a Generic Swirl Burner","volume":"146","author":"Mazzotta","year":"2024","journal-title":"J. Eng. Gas Turbine Power"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"8631","DOI":"10.1021\/acs.energyfuels.7b00709","article-title":"Modeling Combustion of Ammonia\/Hydrogen Fuel Blends under Gas Turbine Conditions","volume":"31","author":"Xiao","year":"2017","journal-title":"Energy Fuels"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"105340","DOI":"10.1016\/j.proci.2024.105340","article-title":"Achieving High Flame Stability with Low NO And Zero N2O and NH3 Emissions during Liquid Ammonia Spray Combustion with Gas Turbine Combustors","volume":"40","author":"Okafor","year":"2024","journal-title":"Proc. Combust. Inst."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"227","DOI":"10.1016\/0045-7930(94)00032-T","article-title":"A new K-epsilon eddy viscosity model for high reynolds numer turbulent flows","volume":"24","author":"Shih","year":"1995","journal-title":"Comput. Fluids"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"10","DOI":"10.2514\/1.29373","article-title":"Effective Inflow Conditions for Turbulence Models in Aerodynamic Calculation","volume":"45","author":"Spalart","year":"2007","journal-title":"AIAA J."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"757","DOI":"10.1063\/1.1748524","article-title":"Evaluated Kinetic Data for Combustion Modeling: Supplement II","volume":"34","author":"Baulch","year":"2005","journal-title":"J. Phys. Chem. Ref. Data"},{"key":"ref_31","unstructured":"(2020). Siemens Industries Digital Software Realizable K-Epsilon Model. SIEMENS STAR-CCM+ Documentation, Siemens."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"23624","DOI":"10.1016\/j.ijhydene.2020.06.083","article-title":"Probing hydrogen\u2013nitrogen chemistry: A theoretical study of important reactions in NxHy, HCN and HNCO oxidation","volume":"45","author":"Li","year":"2020","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"10241","DOI":"10.1021\/jp905454k","article-title":"Thermal Decomposition of NH2OH and Subsequent Reactions: Ab Initiotransition State Theory and Reflected Shock Tube Experiments","volume":"113","author":"Klippenstein","year":"2009","journal-title":"J. Phys. Chem. A"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"518","DOI":"10.1002\/kin.20929","article-title":"Formation of NO from N2\/O2 Mixtures in a Flow Reactor: Toward an Accurate Prediction of Thermal NO","volume":"47","author":"Abian","year":"2015","journal-title":"Internatonal J. Chem. Kinet."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"193","DOI":"10.1016\/S0360-1285(01)00017-X","article-title":"Turbulent Combustion Modeling","volume":"28","author":"Veynante","year":"2002","journal-title":"Prog. Energy Combust. Sci."},{"key":"ref_36","unstructured":"Siemens Industries Digital Software (2020). Reacting Species Transport. SIEMENS STAR-CCM+ Documentation, Siemens."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"105670","DOI":"10.1016\/j.csite.2024.105670","article-title":"Prediction of Ammonia Ignition\/Quenching and Emissions of NOx, NH3 and H2 in a Non-Premixed Swirl Combustor Using the EDC Model","volume":"65","author":"Klimanek","year":"2025","journal-title":"Case Stud. Therm. Eng."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"1403","DOI":"10.1016\/j.ijhydene.2023.12.119","article-title":"Numerical Study on Combustion Characteristics of Ammonia Mixture under Different Combustion Modes","volume":"54","author":"Kuang","year":"2024","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_39","unstructured":"(2020). Siemens Industries Digital Software Participating Media Radiation (DOM). SIEMENS STAR-CCM+ Documentation, Siemens."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"69","DOI":"10.1016\/S0022-4073(02)00046-8","article-title":"Narrow-Band and Full-Spectrum k-Distributions for Radiative Heat Transfer-Correlated-k vs. Scaling Approximation","volume":"76","author":"Modest","year":"2003","journal-title":"J. Quant. Spectrosc. Radiat. Transf."},{"key":"ref_41","doi-asserted-by":"crossref","unstructured":"Mazumder, S., and Roy, S.P. (2023). Modeling Thermal Radiation in Combustion Environments: Progress and Challenges. Energies, 16.","DOI":"10.3390\/en16104250"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"107919","DOI":"10.1016\/j.ijthermalsci.2022.107919","article-title":"Assessment of Various Full-Spectrum Correlated K-Distribution Methods in Radiative Heat Transfer in Oxy-Fuel Sooting Flames","volume":"184","author":"Liu","year":"2023","journal-title":"Int. J. Therm. Sci."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"107695","DOI":"10.1016\/j.jqsrt.2021.107695","article-title":"Comparison and Refinement of the Various Full-Spectrum k-Distribution and Spectral Line Weighted-Sum-of-Gray-Gases Models for Nonhomogeneous Media","volume":"271","author":"Wang","year":"2021","journal-title":"J. Quant. Spectrosc. Radiat. Transf."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"107628","DOI":"10.1016\/j.jqsrt.2021.107628","article-title":"A Machine Learning Based Full-Spectrum Correlated k-Distribution Model for Nonhomogeneous Gas-Soot Mixtures","volume":"268","author":"Zhou","year":"2021","journal-title":"J. Quant. Spectrosc. Radiat. Transf."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"22008","DOI":"10.1016\/j.ijhydene.2020.05.236","article-title":"Stability Limits and NO Emissions of Technically-Premixed Ammonia-Hydrogen-Nitrogen-Air Swirl Flames","volume":"45","author":"Khateeb","year":"2020","journal-title":"Int. J. Hydrogen Energy"},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"19253","DOI":"10.1021\/acs.energyfuels.4c03381","article-title":"Perspectives on NOX Emissions and Impacts from Ammonia Combustion Processes","volume":"18","author":"Mashruk","year":"2024","journal-title":"Energy Fuels"},{"key":"ref_47","unstructured":"Official Journal of the European Union (2010). DIRECTIVE 2010\/75\/EU, European Union."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"4597","DOI":"10.1016\/j.proci.2018.07.083","article-title":"Towards the Development of an Efficient Low-NOx Ammonia Combustor for a Micro Gas Turbine","volume":"37","author":"Okafor","year":"2019","journal-title":"Proc. Combust. Inst."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"112299","DOI":"10.1016\/j.combustflame.2022.112299","article-title":"Evolution of N2O Production at Lean Combustion Condition in NH3\/H2\/Air Premixed Swirling Flames","volume":"244","author":"Mashruk","year":"2022","journal-title":"Combust Flame"},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"7412","DOI":"10.1021\/acs.energyfuels.4c00312","article-title":"Experimental and Numerical Investigation on Combustion Characteristics of Cracked Ammonia Flames","volume":"38","author":"An","year":"2024","journal-title":"Energy Fuels"},{"key":"ref_51","unstructured":"Ammonia Energy Association (2025, February 12). Selective Catalytic Reduction for Marine Ammonia Engines. Available online: https:\/\/ammoniaenergy.org\/articles\/selective-catalytic-reduction-for-marine-ammonia-engines\/."},{"key":"ref_52","unstructured":"suji, I., Ikoma, T., Okamoto, H., and Aoi, N. (2025, February 12). Exhaust Gas Treatment Catalysts for Ammonia-Fueled Engines. Ammonia Energy Conference, Available online: https:\/\/ammoniaenergy.org\/presentations\/exhaust-gas-treatment-catalysts-for-ammonia-fueled-engines\/."},{"key":"ref_53","doi-asserted-by":"crossref","unstructured":"Lasek, J.A., and Lajnert, R. (2022). On the Issues of NOx as Greenhouse Gases: An Ongoing Discussion\u2026. Appl. Sci., 12.","DOI":"10.3390\/app122010429"},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"4648","DOI":"10.1016\/j.atmosenv.2009.04.044","article-title":"Transport Impacts on Atmosphere and Climate: Metrics","volume":"44","author":"Fuglestvedt","year":"2010","journal-title":"Atmos. Environ."},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"40","DOI":"10.1007\/BF02987512","article-title":"Greenhouse Effect of NOx Review Articles","volume":"2","author":"Lammel","year":"1995","journal-title":"Environ. Sci. Pollut. Res."},{"key":"ref_56","doi-asserted-by":"crossref","first-page":"69","DOI":"10.1016\/j.atmosenv.2014.12.043","article-title":"Variation of Radiative Forcings and Global Warming Potentials from Regional Aviation NOx Emissions","volume":"104","author":"Skowron","year":"2015","journal-title":"Atmos. Environ."},{"key":"ref_57","unstructured":"RTE France (2025, February 12). R\u00e9seau de Transport d\u2019\u00c9lectricit\u00e9 ECO2mix\u2014CO2 Emissions per KWh of Electricity Generated in France. Available online: https:\/\/www.rte-france.com\/en\/eco2mix\/co2-emissions."},{"key":"ref_58","unstructured":"Schl\u00f6mer, S., Bruckner, T., Fulton, L., Hertwich Austria, E., McKinnon, A.U., Perczyk, D., Roy, J., Schaeffer, R., H\u00e4nsel, G., and de Jager, D. (2014). Annex III: Technology-specific cost and performance parameters. Climate Change 2014: Mitigation of Climate Change. Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press."},{"key":"ref_59","doi-asserted-by":"crossref","unstructured":"Kim, N., Lee, M., Park, J., Park, J., and Lee, T. (2022). A Comparative Study of NOx Emission Characteristics in a Fuel Staging and Air Staging Combustor Fueled with Partially Cracked Ammonia. Energies, 15.","DOI":"10.3390\/en15249617"},{"key":"ref_60","doi-asserted-by":"crossref","first-page":"111472","DOI":"10.1016\/j.combustflame.2021.111472","article-title":"Enhancement of Ammonia Combustion with Partial Fuel Cracking Strategy: Laminar Flame Propagation and Kinetic Modeling Investigation of NH3\/H2\/N2\/Air Mixtures up to 10 Atm","volume":"231","author":"Mei","year":"2021","journal-title":"Combust Flame"},{"key":"ref_61","doi-asserted-by":"crossref","unstructured":"Romano, C., Bellotti, D., Pucci, E., Fadlun, E., Roma, M., Ghezzi, S., Manferino, G., Anfosso, C., and Monacchini, C. (2024, January 15\u201318). Ammonia Cracking As Auxiliary System for Gas Turbine: Preliminary Studies. Proceedings of the ASME 2024 Power Conference, Washington, DC, USA.","DOI":"10.1115\/POWER2024-137878"}],"container-title":["Energies"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1996-1073\/18\/11\/2919\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T17:46:10Z","timestamp":1760031970000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1996-1073\/18\/11\/2919"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,6,2]]},"references-count":61,"journal-issue":{"issue":"11","published-online":{"date-parts":[[2025,6]]}},"alternative-id":["en18112919"],"URL":"https:\/\/doi.org\/10.3390\/en18112919","relation":{},"ISSN":["1996-1073"],"issn-type":[{"value":"1996-1073","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,6,2]]}}}