TY - GEN A1 - Werner, Adina A1 - Kim, Jongmin A1 - Mauss, Fabian T1 - Excess volumes calculated from UNIQUAC model using the example of methanol - water mixtures T2 - Fluid phase equilibria N2 - Excess volumes can be calculated generally via equations of state. In this work, the excess volumes are obtained using the UNIQUAC model with two approaches of a temperature- and pressure-dependent binary interaction parameter. The pressure dependency is required as the excess volume is derived from the pressure dependency of the excess free enthalpy. Both UNIQUAC approaches are successfully able to predict the vapor-liquid equilibrium as well as the excess volume of methanol-water mixtures over a temperature range between 288.15–473 K and a pressure range between 0.1519–134 bar using a single optimized parameter set. KW - UNIQUAC KW - Excess volume KW - Activity coefficient KW - Pressure dependency Y1 - 2026 U6 - https://doi.org/10.1016/j.fluid.2025.114650 SN - 0378-3812 VL - 603 SP - 1 EP - 13 PB - Elsevier BV CY - Amsterdam ER - TY - GEN A1 - Franken, Tim A1 - Verma, Rakhi A1 - Sharma, Saurabh A1 - Gloesslein, Tobias A1 - Brueger, Arnim A1 - Mauss, Fabian T1 - Modeling of synthetic methane production using Gaussian processes regression T2 - CYPHER Workshop on "Digital Twins for the Decarbonization of hard-to-abate industries" N2 - The production of green gases using Power-to-gas in industry and the energy sector is essential for reducing the carbon footprint. In this process, green hydrogen and carbon dioxide are converted into synthetic methane using nickel catalysts. The carbon dioxide can be obtained from the environment or from point sources such as waste-to-energy plants, combined heat and power plants or industrial furnaces. A one-dimensional model of methane synthesis in the Sabatier reactor enables the simulation of transport processes in the porous medium and the reaction kinetics on the active surface of the nickel catalyst. Despite the low dimensionality, the reactor model is still computationally intensive, as it must solve the reaction mechanism of heterogeneous surface reactions and the mass and heat transport. The introduction of Gaussian processes regression can help to significantly reduce the computational effort for the prediction of species and temperature in the Sabatier reactor under different thermodynamic conditions. This allows for faster turnaround times, enables the application of advanced methods like optimization and more. The accuracy of a Gaussian processes regression is investigated in this work. KW - Gaussian Processes KW - Machine Learning KW - Reactor Y1 - 2024 UR - https://www.researchgate.net/publication/384441411_Modeling_of_synthetic_methane_production_using_Gaussian_processes_regression ER - TY - GEN A1 - Shrestha, Krishna Prasad A1 - Giri, Binod Raj A1 - Pelé, Ronan A1 - Aljohani, Khalid A1 - Brequigny, Pierre A1 - Mauss, Fabian A1 - Halter, Fabien A1 - Huynh, Lam K. A1 - Mounaïm-Rousselle, Christine T1 - A comprehensive chemical kinetic modeling and experimental study of NH₃−methanol/ethanol combustion towards net-zero CO₂ emissions T2 - Combustion and flame N2 - Ammonia is gaining attention as a green fuel with the potential to reduce carbon emissions. Its versatility allows it to be used directly in combustion engines, fuel cells, and as a hydrogen carrier, making it a key candidate for sustainable energy applications. This study provides a comprehensive analysis of the oxidation kinetics of ammonia (NH3) blends with methanol (CH3OH) and ethanol (C2H5OH) under diverse conditions. We measured laminar flame speeds of different NH3-alcohol blends — varying CH3OH/C2H5OH ratios (0–100 %) — using a constant volume combustion chamber across temperatures from 503 to 645 K and pressures of 2–11.3 bar. We also obtained the ignition delay times for NH3/C2H5OH blends with 10 % and 30 % (by mole) C2H5OH using a shock tube at pressures of 1, 10, and 20 bar and temperatures of 1100–1500 K. Our results show that incorporating CH3OH and C2H5OH into NH3 increases the laminar flame speed, with C2H5OH being a more effective promoter than CH3OH due to its higher contribution to the formation of reactive radicals (OH, H, and O). Our model suggests that at high temperatures, both CH3OH and C2H5OH contribute to increased NO formation, with C2H5OH being more effective in reducing N2O emissions than CH3OH. In shock tube experiments, adding C2H5OH significantly shortens ignition delay times of NH3. At low temperatures (in the rapid compression machine case), the sensitivity to ignition delay times decreases when the CH3OH/C2H5OH content exceeds 5 % in NH3-alcohol blends. C2H5OH is a more effective combustion promoter, enhancing NH3 reactivity and reducing NOx emission more efficiently than CH3OH. We developed a detailed kinetic model, building on our previous work, and validated it against new experimental and literature data. Our model accurately predicts the combustion behavior of neat NH3 and NH3 fuel blends and serves as a base for future research on NH3 blended with higher hydrocarbons and/or oxygenated blends. KW - Ammonia KW - Methanol KW - Ethanol KW - Kinetic modeling KW - Laminar flame speed KW - Ignition delay time Y1 - 2025 U6 - https://doi.org/10.1016/j.combustflame.2024.113954 SN - 0010-2180 VL - 274 SP - 1 EP - 21 PB - Elsevier BV CY - Amsterdam ER - TY - GEN A1 - Pasternak, Michał A1 - Przybyła, Grzegorz A1 - Siddareddy, Reddy A1 - Lewandowski, Michał A1 - Bjørgen, Karl A1 - Mauss, Fabian A1 - Nadimi, Ebrahim A1 - Peczkis, Grzegorz A1 - Zhou, Min-min A1 - Adamczyk, Wojciech T1 - Development of ammonia-biodiesel fueled agricultural tractor : aspects of retrofitting a compression ignition engine to direct ammonia injection T2 - Energy N2 - The automotive industry has shown growing interest in ammonia as a carbon-free fuel, which holds potential for mitigating the greenhouse effect. Nonetheless, adapting current combustion engines to use ammonia necessitates prior modifications. This paper introduces a retrofitting technique for converting an existing compression ignition engine into one powered by a direct injection of ammonia and biodiesel. The development results from collaboration between Polish and Norwegian research teams as part of the ACTIVATE project (Ammonia as carbon-free fuel for internal combustion engine-driven agricultural vehicles). The new technology is grounded on experimental and numerical research involving a single-cylinder engine installed in a small agricultural tractor. Biodiesel was directly injected to initiate ammonia combustion. Experimental activities were performed on engine test benches and a chassis dynamometer, complemented by 0D and 3D simulations using the stochastic reactor model and CFD code Converge, respectively. A comprehensive exploration of engine operating conditions and fuel injection strategies was undertaken experimentally and numerically to assess the potential benefits and drawbacks of various designs. A segment of the research focused on analyzing nitrous oxide formation, given its significant impact on global warming. The investigations resulted in a method for combusting ammonia with biodiesel as an ignition enhancer. It was determined that maintaining a stable engine operation in a tractor under real driving scenarios requires 47% of the energy sourced from ammonia. Optimal engine performance occurs when ammonia and biodiesel are injected near the end of the compression stroke, closely followed by the ignition promoter. A prolonged interval between these injections impairs combustion efficiency and raises ammonia emissions. The integrated numerical and experimental research resulted in a demonstration tractor fueled by directly injected biodiesel and ammonia. Y1 - 2025 U6 - https://doi.org/10.1016/j.energy.2025.136255 SN - 0360-5442 VL - 327 SP - 1 EP - 14 PB - Elsevier BV CY - Amsterdam ER - TY - GEN A1 - Hemaizia, Abdelkader A1 - Verma, Rakhi A1 - Guan, Wei A1 - Mauss, Fabian A1 - Thévenin, Dominique ED - Mauss, Fabian T1 - The influence of hydrocarbon additives on laminar burning velocity and NOx emissions in hydrogen‐air combustion T2 - Proceedings in applied mathematics and mechanics : PAMM N2 - Hydrogen is a promising carbon‐free fuel but faces challenges due to combustion instability and nitrogen oxide () emissions during combustion. This study investigates the potential of blending hydrocarbons (methane, propane) or ammonia with hydrogen‐air flames in order to minimize these challenges. Simulations were performed using a one‐dimensional, freely‐propagating, adiabatic premixed flame (FPPF) model in Cantera, incorporating detailed kinetic and thermodynamic modeling. Updated, detailed, and reduced reaction mechanisms were utilized to accurately represent the chemical kinetics of the selected fuel blends. We analyzed laminar flame velocity (LFV), flame structure, and emissions of and CO across a range of inlet pressures, temperatures, equivalence ratios, and blend ratios of /, /, and /. The results were validated against experimental data. Propane addition (10% –60% vol.) was found to be the most effective solution to reduce emissions by promoting reburning pathways that convert NO to , while moderately reducing LFV. Methane exhibits a comparable effect in suppressing thermal while slightly reducing LFV. Ammonia drastically lowers via fuel‐bound nitrogen pathways but sharply increases CO emissions and destabilizes flames at high concentrations. By identifying key reaction pathways governing formation (thermal, prompt, , NNH, and reburning), propane is finally selected as the optimal additive for achieving low‐ hydrogen combustion, despite its trade‐off with LFV, providing critical insights for designing cleaner and more stable combustion systems. Y1 - 2025 U6 - https://doi.org/10.1002/pamm.70028 SN - 1617-7061 VL - 25 IS - 4 SP - 1 EP - 13 PB - Wiley CY - Weinheim ER - TY - GEN A1 - Verma, Rakhi A1 - Günther, Vivien A1 - Giri, Binod Raj A1 - Hemaizia, Abdelkader A1 - Thévenin, Dominique A1 - Mauss, Fabian T1 - Kinetic modeling of CO₂ methanation for methane production : a comprehensive study T2 - IFAC-PapersOnLine N2 - To understand the complex methanation reaction, experiments have been conducted at various operating conditions, for instance, temperature, inlet gas dilution, and inlet composition. In addition, a detailed surface reaction mechanism is developed to conduct the study numerically by validating the simulation results with the experimental data. The kinetic model developed in this study is able to capture the experimental trends successfully for all conditions considered for the analysis. Y1 - 2025 U6 - https://doi.org/10.1016/j.ifacol.2025.12.175 SN - 2405-8963 VL - 59 IS - 29 SP - 18 EP - 23 PB - Elsevier BV CY - Amsterdam ER - TY - GEN A1 - Verma, Rakhi A1 - Günther, Vivien A1 - Giri, Binod Raj A1 - Mauss, Fabian T1 - Effect of pressure and nitrogen dilution on surface species and reaction kinetics in CO₂ methanation over Ni catalyst T2 - IFAC-PapersOnLine N2 - The CO2 methanation process is studied under varying pressures to support the development of efficient and sustainable technologies aligned with emission reduction and hydrogen economy goals. Experiments at two pressures, followed by pressure-dependent simulations, show strong agreement. Additionally, surface species coverage is analyzed, offering insights into catalytic behavior. These findings aid in optimizing methanation by deepening understanding of reaction mechanisms and guiding the design of improved catalysts. KW - Kinetic modeling KW - CO₂ methanation KW - Sabatier reaction KW - Power to gas (P2G) KW - Synthetic natural gas (SNG) Y1 - 2025 U6 - https://doi.org/10.1016/j.ifacol.2025.12.172 SN - 2405-8963 VL - 59 IS - 29 SP - 1 EP - 5 PB - Elsevier BV CY - Amsterdam ER - TY - GEN A1 - Verma, Rakhi A1 - Mauss, Fabian T1 - Equilibrium analysis for methanation focusing on CO₂ derived substitute natural gas T2 - Proceedings of the Second SIMS EUROSIM Conference on Modelling and Simulation, SIMS EUROSIM 2024 N2 - In this study the methanation of synthesis gas (syngas) is investigated with a focus on achieving maximum methane and minimum CO by full methanation of CO2. For this study, we have considered a comprehensive thermodynamics analysis of CO2 hydrogenation. This will help us to understand the thermodynamic behaviour of the reactions involved in the methanation process. We have discussed the behavior of the species, CO2, H2, CH4, and H2O at the equilibrium with temperature, pressure, and fuel ratio variation in order to get the desired output. The preliminary study will focus on selecting the optimum conditions (temperature, pressure, and H2/CO2 ratio) for performing the experiments and for catalyst development. Y1 - 2025 SN - 978-91-8075-984-7 U6 - https://doi.org/10.3384/ecp212.022 SN - 1650-3686 VL - 211 SP - 162 EP - 167 PB - Linköping University Electronic Press CY - Linköping ER - TY - GEN A1 - Hemaizia, Abdelkader A1 - Verma, Rakhi A1 - Mauss, Fabian A1 - Thévenin, Dominique T1 - On the impact of swirl number on premixed C3H8/air combustion in a bluff-body burner T2 - IFAC-PapersOnLine N2 - Utilizing ANSYS-Fluent 21.0, large eddy simulations (LES) of the reactive flow in the Volvo bluff-body burner under various swirl intensities were performed. The Eddy Dissipation Concept (EDC) model coupled with a reduced chemical mechanism was employed to simulate premixed combustion. Results show thatLES is able to capture the interaction between swirl strength and fame stabilization behind the bluff-body. High swirl numbers generate strong central recirculation zones (CRZ), which enhance fame anchoring and combustion efficiency through increased hot gas recirculation and improved turbulent mixing. KW - Propane KW - Bluff-body burner KW - Large eddy simulation (LES) KW - Premixed combustion KW - Swirl number KW - Central recirculation zone (CRZ) KW - Flame stabilization KW - Turbulent reacting flow KW - Eddy dissipation concept (EDC) Y1 - 2025 U6 - https://doi.org/10.1016/j.ifacol.2025.12.201 SN - 2405-8963 VL - 59 IS - 29 SP - 174 EP - 179 PB - Elsevier BV CY - Amsterdam ER - TY - GEN A1 - Siddareddy, Reddy Babu A1 - Pasternak, Michał A1 - de Syniawa, Larisa León A1 - Guenther, Vivien A1 - Seidel, Lars A1 - Mauss, Fabian A1 - Przybyła, Grzegorz A1 - Adamczyk, Wojciech T1 - Simulations of the SCR catalyst in ammonia-biodiesel fuelled CI engine using virtual test bench with detailed chemistry T2 - Renewable energy N2 - The use of ammonia as an alternative fuel in the automotive industry is not yet fully established. Further research and development are required to account for both engine and aftertreatment systems, as well as their integration and control to ensure the most efficient use of ammonia. In this work, we present a fully physics and chemistry-based toolchain for co-simulating an ammonia-biodiesel fuelled compression ignition engine with a selective catalytic reduction catalyst. The investigations refer to experimental data from a single-cylinder research engine. This is a direct injection engine that was retrofitted to run on ammonia and biodiesel, the latter acting as a combustion promoter. Engine in-cylinder processes were simulated using a stochastic reactor model. Detailed gas phase chemistry is used to simulate the combustion process and pollutants formation. The catalyst model employs detailed surface chemistry that is trained using available data from literature. Eventually, the co-simulation toolchain was applied to investigate numerically the impact of the properties of the catalyst on ammonia reduction under engine-relevant operating conditions KW - Ammonia combustion KW - Selective reduction catalyst KW - Stochastic reactor model KW - Detailed chemistry KW - Exhaust emissions Y1 - 2025 U6 - https://doi.org/10.1016/j.renene.2025.123169 SN - 0960-1481 VL - 251 SP - 1 EP - 12 PB - Elsevier BV CY - Amsterdam ER - TY - GEN A1 - Welp, Alexandra A1 - Rudolph, Charlotte A1 - Giri, Binod Raj A1 - Shrestha, Krishna Prasad A1 - Verma, Rakhi A1 - Mauss, Fabian A1 - Atakan, Burak T1 - Oxidation kinetics of ammonia methanol blends : an experimental and kinetic modeling study T2 - Combustion and flame N2 - Ammonia is emerging as a key hydrogen energy carrier for decarbonization. However, its low reactivity necessitates blending with hydrocarbons and/or oxygenates, such as alcohols, to improve combustion properties. Understanding the oxidation kinetics of such blends is essential for evaluating ammonia’s potential as a sustainable fuel. The experimental data on ammonia blended with simple alcohols like methanol remains scarce. This study investigates the oxidation kinetics of ammonia/methanol blends for the first time using a plug-flow reactor coupled with a time-of-flight mass spectrometer setup. This advanced setup enabled simultaneous quantification of temperature-dependent reactant conversion and product distribution over a temperature range of 373–973 K, a pressure of 3 bar, and equivalence ratios of 1 and 2. Adding 10 % methanol significantly enhances radical formation, reducing oxidation onset temperature compared to neat ammonia. Interestingly, the conversion onset temperature was only slightly influenced by the mixture composition or the equivalence ratio. The temperature dependence of the product distribution as a function of the equivalence ratio was further analyzed. Experimental results were compared to simulation using selected kinetic models from the literature, revealing significant disparities in predicting capabilities. Among the kinetic models, Shrestha 2025, He 2023 and Wang 2024 performed well, capturing our experimental data for NH3/CH3OH blends. Reaction flux and sensitivity analyses highlighted some key reactions involving the reactive combustion species (OH, HO2 and NH2), such as CH3OH+HO2 ⇌ CH2OH+H2O2 and CH3OH+NH2, governing the oxidation kinetics of NH3/CH3OH blends. This combined experimental and kinetic modeling approach provides valuable insights into fundamental reaction mechanisms of NH3/CH3OH blends, aiding the development of cleaner and more efficient combustion systems. KW - Ammonia KW - Methanol KW - Kinetic investigation KW - Plug-flow reactor KW - Mass spectrometry Y1 - 2025 U6 - https://doi.org/10.1016/j.combustflame.2025.114210 SN - 0010-2180 VL - 278 SP - 1 EP - 11 PB - Elsevier BV CY - Amsterdam ER - TY - GEN A1 - Rothe, Paul A1 - Bikas, Georgios A1 - Mauss, Fabian T1 - Investigation of the combustion process of a thermally conditioned active prechamber in monovalent operation with ammonia T2 - SAE technical papers N2 - The debate over synthetic fuels is intense especially in sectors with a high energy demand like maritime [1, 2]. Hydrogen production from renewable sources is growing, but immediate measures for decarbonization are needed [3, 4]. In this context, the project MethMag was funded, and a gas engine for methane combustion with an innovative cooling concept and a purged prechamber (PC) spark plug was virtually developed [5, 6]. Validation with data from the test bench demonstrates that the simulations accurately represent the operating conditions [7, 8]. This combustion process is adapted for ammonia, which is being considered as a climate-friendly fuel of the future, particularly in maritime transportation [4, 9]. This fuel faces significant combustion challenges and is therefore mostly considered in complex, bivalent systems [10]. In particular, the prechamber is examined regarding the ignitability of ammonia. The overarching objective is to eliminate the necessity for a secondary fuel system, thereby reducing system complexity and associated costs. The transition to ammonia highlights the need for further adjustments. The geometry of the PC cap significantly affects turbulence and mixture formation in the prechamber [11]. While swirl caps generate high turbulence, the mixture formation is inadequate. Tumble caps, on the other hand, provide advantages in mixture formation by achieving an earlier increase in turbulence, even though the maximum turbulence is lower. For ammonia combustion, PC wall conditioning is not essential, given the inherently low combustion temperatures. However, conditioning can improve cold-start behavior by accelerating PC combustion and offering greater flexibility in ignition timing [12]. Direct injection into the prechamber enhances fuel mixing and reduces sensitivity to ignition timing adjustments. This leads to higher efficiency and better combustion characteristics, particularly at lean air-fuel ratios [13, 14]. Operating with a lean ammonia-air mixture is challenging but offers benefits for non-selective catalytic reduction (non-SCR) of nitrogen oxides. Simulations show that operation with λ = 1.2 and λ = 1.4 is feasible, although efficiency decreases at leaner mixtures [15]. KW - Air / fuel ratio KW - Ignition timing KW - Ignition systems KW - Gas engines KW - Combustion and combustion processes KW - Nitrogen oxides KW - Synthetic fuels KW - Fuel injection KW - Test equipment and instrumentation KW - Fuel systems Y1 - 2025 U6 - https://doi.org/10.4271/2025-24-0028 SN - 0148-7191 PB - SAE International CY - Warrendale, PA ER - TY - GEN A1 - Udaybhanu, Gadi A1 - Giri, Binod R. A1 - Lee, Bok Jik A1 - Shrestha, Krishna P. A1 - Roberts, William L A1 - Mauss, Fabian A1 - Reddy, V. Mahendra T1 - Investigation of staging techniques for hydrocarbon-assisted ammonia flames in a novel dual-stage combustor T2 - Combustion and flame N2 - Ammonia presents itself as a high-hydrogen dense and carbon-free alternative for industrial heating, power generation, and transportation. Nevertheless, the challenges of its low flame speed and elevated NOx (nitrogen oxides) emissions pose significant challenges in combustor applications. This study investigates a novel two-stage burner employing a radial injection staging technique and explores various NOx reduction strategies for hydrocarbon-assisted ammonia flames. These strategies include premixing, fuel staging, balanced fuel staging, air staging, and sequential premixing. The focus is on LPG (liquid petroleum gas)-stabilized ammonia flames. The experiments are conducted at a constant thermal input of 20 kW (10 kW LPG + 10 kW NH3), with global equivalence ratios ranging from 0.7 to 1.4. This approach aims to provide valuable insights into the effectiveness of different staging strategies for NOx reduction in ammonia combustion. Experimental analysis is undertaken to ascertain the flame stabilization, flame temperature and its reaction zone, intermediate species and major emissions like NOx and NH3 of the burner. Staging configuration strongly influenced flame stabilization, heat release distribution, and thermal field, with downstream-shifted combustion zones lowering peak temperatures and NOx formation. Among the tested strategies, fuel staging and sequential premixing consistently achieved the greatest NOx reduction across the entire operating range compared to the premixed baseline, without compromising flame stability. Chemical kinetics analysis further reveals the dominant NO formation pathways, highlighting the key roles of HNO and NHi radicals. Additionally, this analysis helps identify dominant reaction routes and the role of intermediate species in NO formation and reduction processes. The combined experimental and kinetic insights provide a mechanistic basis for optimizing staged combustion of ammonia-hydrocarbon blends for lower NOx emissions. KW - Ammonia combustion KW - Nox reduction KW - Staging techniques KW - Flame stabilization KW - Radial injection KW - Kinetic analysis Y1 - 2026 U6 - https://doi.org/10.1016/j.combustflame.2025.114607 SN - 0010-2180 VL - 284 SP - 1 EP - 12 PB - Elsevier BV CY - Amsterdam ER - TY - GEN A1 - Asgarzade, Rufat A1 - Franken, Tim A1 - Mauss, Fabian ED - Hemaizia, Abdelkader T1 - Multi-objective optimization of oxyfuel gas engine using stochastic engine model and detailed chemistry T2 - SAE technical papers N2 - The energy transition initiatives in Germany’s renown coal mining region Lusatia have driven research into Power-to-X-to-Power technologies, where synthetic fuel is produced from renewably sourced hydrogen and captured CO2, and converted to electricity and heat through oxyfuel combustion. This work investigates the multi-objective optimization of oxyfuel gas engine using a stochastic engine model and detailed chemistry. Exhaust gas recirculation (EGR) rate, initial cylinder temperature and pressure, spark timing, piston bowl radius and depth are selected as design parameters to minimize the exhaust temperature at exhaust valve opening and indicated specific fuel consumption (ISFC) corresponding to oxyfuel operation with different dry and wet EGR rates. The optimization problem is solved for a dry EGR and four wet EGR cases with various CO2/H2O fractions, aiming to achieve comparable performance as in conventional natural gas / air operation, and energy-efficient carbon capture. The case with the lowest humidity (T10deg) had the lowest temperature of 1537 K, while the one with the highest vapor fraction (T70deg) attained the minimum 260 g/kWh ISFC. The superiority of the T10deg case is offset by much higher cooling demand (3.06 kW) for CO2 separation than that for T70deg case (0.81 kW). The constraint for combustion efficiency (>65%) limited the solution space towards high ISFC values, while the constraint for low indicated mean effective pressure (IMEP) (>7 bar) and the constraint for high IMEP (<8 bar) limited the solution space in between the two distinct clusters of feasible designs, and towards high exhaust temperature, respectively. The optimized designs from all the cases could outperform the reference case in terms of IMEP, nevertheless they fell below 31% indicated efficiency, which is associated with stoichiometric combustion. KW - Gas engines KW - Greenhouse gas emissions KW - Exhaust gas recirculation (EGR) KW - Ignition timing KW - Synthetic fuels KW - Fuel consumption KW - Carbon dioxide KW - Combustion and combustion processes KW - Natural gas KW - Engines Y1 - 2025 U6 - https://doi.org/10.4271/2025-01-0529 SN - 0148-7191 PB - SAE International CY - Warrendale, PA, United States ER - TY - GEN A1 - El Harrab, Hayat A1 - Askar, Enis A1 - Franken, Tim A1 - Mauss, Fabian T1 - Experimental and reaction kinetic study of hydrogen ignition behavior at ignition limits T2 - Proceedings of the Combustion Institute N2 - 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 . 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 and , 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. KW - Hydrogen KW - Auto-ignition temperature KW - Ignition limit KW - Radical wall termination reaction Y1 - 2025 U6 - https://doi.org/10.1016/j.proci.2025.105980 SN - 1540-7489 VL - 41 SP - 1 EP - 7 PB - Elsevier BV CY - Amsterdam ER -