@misc{AsgarzadeFrankenMauss, author = {Asgarzade, Rufat and Franken, Tim and Mauss, Fabian}, title = {Experimental investigation of CH4/O2/CO2 mixtures in a single-cylinder spark ignition engine}, pages = {1}, abstract = {The Power-to-X-to-Power (P2X2P) technology involves producing synthetic methane from renewable hydrogen and captured CO2, which is then used for cogeneration of electricity and heat through oxyfuel combustion. With the P2X2P energy system demonstrator, NOx-free and carbon neutral heat and electricity generation as well as storage of excess renewable energy are realized. This work presents the experimental investigation of combustion characteristics for CH4/O2/CO2 mixtures in a single cylinder spark ignition engine that is a part of the P2X2P system.}, language = {en} } @misc{AsgarzadeFrankenMauss, author = {Asgarzade, Rufat and Franken, Tim and Mauss, Fabian}, title = {Development of an oxyfuel engine test bench for power-to-X-to-power application}, series = {12th European Combustion Meeting}, journal = {12th European Combustion Meeting}, pages = {1}, abstract = {This work presents the development of an oxyfuel engine test bench which is integrated into a Power-to-X-to-Power energy storage system demonstrator. These storage systems are considered carbon-free because they recirculate carbon without emitting it into the atmosphere.}, language = {en} } @misc{AsgarzadeFrankenMauss, author = {Asgarzade, Rufat and Franken, Tim and Mauss, Fabian}, title = {Oxyfuel combustion process development for an SI engine in a power-to-X-to-power energy system}, pages = {1}, abstract = {This work presents the development of an oxyfuel engine test bench which is to be integrated to a Power-to-X-to-Power energy storage system demonstrator. Such storage systems are considered carbon-neutral because they recirculate carbon without emitting it into the atmosphere.}, language = {en} } @misc{WernerKimMauss, author = {Werner, Adina and Kim, Jongmin and Mauss, Fabian}, title = {Excess volumes calculated from UNIQUAC model using the example of methanol - water mixtures}, series = {Fluid phase equilibria}, volume = {603}, journal = {Fluid phase equilibria}, publisher = {Elsevier BV}, address = {Amsterdam}, issn = {0378-3812}, doi = {10.1016/j.fluid.2025.114650}, pages = {1 -- 13}, abstract = {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.}, language = {en} } @misc{FrankenVermaSharmaetal., author = {Franken, Tim and Verma, Rakhi and Sharma, Saurabh and Gloesslein, Tobias and Brueger, Arnim and Mauss, Fabian}, title = {Modeling of synthetic methane production using Gaussian processes regression}, series = {CYPHER Workshop on "Digital Twins for the Decarbonization of hard-to-abate industries"}, journal = {CYPHER Workshop on "Digital Twins for the Decarbonization of hard-to-abate industries"}, abstract = {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.}, language = {en} } @misc{ShresthaGiriPeleetal., author = {Shrestha, Krishna Prasad and Giri, Binod Raj and Pel{\´e}, Ronan and Aljohani, Khalid and Brequigny, Pierre and Mauss, Fabian and Halter, Fabien and Huynh, Lam K. and Mouna{\"i}m-Rousselle, Christine}, title = {A comprehensive chemical kinetic modeling and experimental study of NH₃-methanol/ethanol combustion towards net-zero CO₂ emissions}, series = {Combustion and flame}, volume = {274}, journal = {Combustion and flame}, publisher = {Elsevier BV}, address = {Amsterdam}, issn = {0010-2180}, doi = {10.1016/j.combustflame.2024.113954}, pages = {1 -- 21}, abstract = {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.}, language = {en} } @misc{PasternakPrzybyłaSiddareddyetal., author = {Pasternak, Michał and Przybyła, Grzegorz and Siddareddy, Reddy and Lewandowski, Michał and Bj{\o}rgen, Karl and Mauss, Fabian and Nadimi, Ebrahim and Peczkis, Grzegorz and Zhou, Min-min and Adamczyk, Wojciech}, title = {Development of ammonia-biodiesel fueled agricultural tractor : aspects of retrofitting a compression ignition engine to direct ammonia injection}, series = {Energy}, volume = {327}, journal = {Energy}, publisher = {Elsevier BV}, address = {Amsterdam}, issn = {0360-5442}, doi = {10.1016/j.energy.2025.136255}, pages = {1 -- 14}, abstract = {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.}, language = {en} } @misc{HemaiziaVermaGuanetal., author = {Hemaizia, Abdelkader and Verma, Rakhi and Guan, Wei and Mauss, Fabian and Th{\´e}venin, Dominique}, title = {The influence of hydrocarbon additives on laminar burning velocity and NOx emissions in hydrogen-air combustion}, series = {Proceedings in applied mathematics and mechanics : PAMM}, volume = {25}, journal = {Proceedings in applied mathematics and mechanics : PAMM}, number = {4}, editor = {Mauss, Fabian}, publisher = {Wiley}, address = {Weinheim}, issn = {1617-7061}, doi = {10.1002/pamm.70028}, pages = {1 -- 13}, abstract = {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.}, language = {en} } @misc{VermaGuentherGirietal., author = {Verma, Rakhi and G{\"u}nther, Vivien and Giri, Binod Raj and Hemaizia, Abdelkader and Th{\´e}venin, Dominique and Mauss, Fabian}, title = {Kinetic modeling of CO₂ methanation for methane production : a comprehensive study}, series = {IFAC-PapersOnLine}, volume = {59}, journal = {IFAC-PapersOnLine}, number = {29}, publisher = {Elsevier BV}, address = {Amsterdam}, issn = {2405-8963}, doi = {10.1016/j.ifacol.2025.12.175}, pages = {18 -- 23}, abstract = {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.}, language = {en} } @misc{VermaGuentherGirietal., author = {Verma, Rakhi and G{\"u}nther, Vivien and Giri, Binod Raj and Mauss, Fabian}, title = {Effect of pressure and nitrogen dilution on surface species and reaction kinetics in CO₂ methanation over Ni catalyst}, series = {IFAC-PapersOnLine}, volume = {59}, journal = {IFAC-PapersOnLine}, number = {29}, publisher = {Elsevier BV}, address = {Amsterdam}, issn = {2405-8963}, doi = {10.1016/j.ifacol.2025.12.172}, pages = {1 -- 5}, abstract = {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.}, language = {en} } @misc{VermaMauss, author = {Verma, Rakhi and Mauss, Fabian}, title = {Equilibrium analysis for methanation focusing on CO₂ derived substitute natural gas}, series = {Proceedings of the Second SIMS EUROSIM Conference on Modelling and Simulation, SIMS EUROSIM 2024}, volume = {211}, journal = {Proceedings of the Second SIMS EUROSIM Conference on Modelling and Simulation, SIMS EUROSIM 2024}, publisher = {Link{\"o}ping University Electronic Press}, address = {Link{\"o}ping}, isbn = {978-91-8075-984-7}, issn = {1650-3686}, doi = {10.3384/ecp212.022}, pages = {162 -- 167}, abstract = {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.}, language = {en} }