TY - GEN A1 - Franken, Tim A1 - Duggan, Alexander A1 - Tao, Feng A1 - Matrisciano, Andrea A1 - Lehtiniemi, Harry A1 - Borg, Anders A1 - Mauß, Fabian T1 - Multi-Objective Optimization of Fuel Consumption and NOx Emissions of a heavy-duty Diesel engine using a Stochastic Reactor Model T2 - SAE technical paper N2 - Highly fuel-efficient Diesel engines, combined with effective exhaust aftertreatment systems, enable an economic and low-emission operation of heavy-duty vehicles. The challenge of its development arises from the present engine complexity, which is expected to increase even more in the future. The approved method of test bench measurements is stretched to its limits, because of the high demand for large parameter variations. The introduction of a physics-based quasi-dimensional stochastic reactor model combined with tabulated chemistry enables the simulation-supported development of these Diesel engines. The stochastic reactor model mimics mixture and temperature inhomogeneities induced by turbulence, direct injection and heat transfer. Thus, it is possible to improve the prediction of NOx emissions compared to common mean-value models. To reduce the number of designs to be evaluated during … KW - Highly fuel-efficient Diesel engines Y1 - 2019 SN - 0096-5170 SN - 0148-7191 IS - 2019-01-1173 ER - TY - GEN A1 - Malliotakis, Zisis A1 - Banyon, Colin A1 - Zhang, Kuiwen A1 - Wagnon, Scott W. A1 - Rodriguez Henriquez, Jose Juan A1 - Vourliotakis, George A1 - Keramiotis, Christos A1 - Founti, Maria A1 - Mauß, Fabian A1 - Pitz, William J. A1 - Curran, Henry J. T1 - Testing the validity of a mechanism describing the oxidation of binary n-heptane/toluene mixtures at engine operating conditions T2 - Combustion and Flame N2 - The aim of this work is to evaluate the influence of the n-heptane/toluene ratio on the reactivity of binary toluene reference fuels (TRFs), through a combined experimental and numerical work. Novel experimental ignition delay time (IDT) data of three binary TRFs of varying n-heptane/toluene ratios have been obtained in a high-pressure shock tube and in a rapid compression machine at conditions relevant to novel engine operation. Measurements have been performed at two pressures (10 and 30 bar), and at three fuel/air equivalence ratios (0.5, 1.0 and 2.0) for TRF mixtures of 50%, 75% and 90% by volume toluene concentration, over the temperature range of 650–1450 K. It was found that, increasing the n-heptane content, led to an increase in reactivity and shorter measured IDTs. Reduced sensitivity to the equivalence ratio was observed at high temperatures, especially for high toluene content mixtures. A … KW - The aim of this work is to evaluate the influence of the n-heptane/toluene Y1 - 2019 U6 - https://doi.org/10.1016/j.combustflame.2018.10.024 SN - 0010-2180 VL - 199 SP - 241 EP - 248 ER - TY - GEN A1 - Franken, Tim A1 - Klauer, Christian A1 - Kienberg, Martin A1 - Matrisciano, Andrea A1 - Mauß, Fabian T1 - Prediction of thermal stratification in an engine-like geometry using a zero-dimensional stochastic reactor model T2 - International Journal of Engine Research KW - Prediction of thermal stratification Y1 - 2019 UR - https://journals.sagepub.com/eprint/5AKgEhAVA8RDS2tQWdGK/full SN - 2041-3149 U6 - https://doi.org/10.1177/1468087418824217 SN - 1468-0874 ER - TY - GEN A1 - Shrestha, Krishna Prasad A1 - Seidel, Lars A1 - Zeuch, Thomas A1 - Mauß, Fabian T1 - Kinetic Modeling of NOx Formation and Consumption during Methanol and Ethanol Oxidation T2 - Combustion Science and Technology KW - Kinetic Modeling of NOx Formation Y1 - 2019 U6 - https://doi.org/10.1080/00102202.2019.1606804 SN - 1563-521X VL - 191 IS - 9 SP - 1628 EP - 1660 ER - TY - GEN A1 - Netzer, Corinna A1 - Seidel, Lars A1 - Ravet, Frédéric A1 - Mauß, Fabian T1 - Impact of the surrogate formulation on 3D CFD engine knock prediction using detailed chemistry T2 - Fuel N2 - For engine knock prediction, surrogate fuels are often composed of iso-octane and n-heptane since they are the components of the Primary Reference Fuel (PRF). By definition, a PRF has no octane sensitivity (S = RON-MON). However, for a commercial gasoline fuel holds RON > MON and therefor S > 0. More complex surrogates are Toluene Reference Fuels (TRF) and Ethanol containing Toluene Reference Fuels (ETRF). In this work, the impact of the surrogate formulation on the prediction of flame propagation and auto-ignition in the unburnt gases are investigated. The surrogates are composed such that the Research Octane Number is the same. The auto-ignition events ahead of the flame front are predicted using 3D CFD and a combustion model based on the ETRF mechanism by Seidel (2017). The strength of the auto-ignition is determined using the detonation diagram by Bradley and co-workers (2002, 2003). Applying the different surrogates, ignition kernels of different size and reactivity are predicted. The results indicate a dependency on the local temperature history and the low temperature chemistry of the fuel species. The comparison of homogenous constant volume reactor and transient simulations show that the analysis of ignition delay time and octane rating solely from homogenous simulations is not sufficient if the knock tendency of a surrogate in engine simulations needs to be characterized. Y1 - 2019 U6 - https://doi.org/10.1016/j.fuel.2019.115678 SN - 1873-7153 VL - Volume 254 ER - TY - GEN A1 - Gern, Maike Sophie A1 - Kauf, Georg Malte A1 - Vacca, Antonino A1 - Franken, Tim A1 - Kulzer, André Casal T1 - Ganzheitliche Methode zur Bewertung der Wassereinspritzung T2 - MTZ - Motortechnische Zeitschrift N2 - Die künftige Effizienzsteigerung bei Ottomotoren mit Direkteinspritzung sowie die Reduktion von gas- und partikelförmigen Emissionen erfordern innovative Ansätze. Durch die neue RDEGesetzgebung für leichte Kraftfahrzeuge verschiebt sich der Fokus hin zu dynamischen Testzyklen mit 12 % mehr Hochlastbetriebspunkten im Vergleich zum WLTC (Worldwide harmonized Light Duty Test Cycle). Die Steigerung des Mitteldrucks bei Ottomotoren führt zu einem effizienten Betrieb, der jedoch durch das Risiko irregulärer Verbrennung und hohen Abgastemperaturen limitiert ist. Durch den Einsatz von Wassereinspritzung können sowohl die Klopfneigung als auch die Abgastemperatur reduziert werden, was den Schutz der Abgasnachbehandlungskomponenten bei gleichzeitiger Wirkungsgradsteigerung ermöglicht. Im Rahmen des FVV-Projekts „Wassereinspritzung bei Ottomotoren“ wird der Einfluss der NiederdruckWassereinspritzung (NDWE) und Hochdruck-Wassereinspritzung (HDWE) untersucht. Insbesondere die Auswirkungen auf Gemischbildung, Verbrennung und Abgasnachbehandlung werden durch die Vernetzung von Experiment und Simulation analysiert. KW - Water Injection KW - Wassereinspritzung KW - Gasoline KW - Simulation KW - Efficiency Y1 - 2019 U6 - https://doi.org/10.1007/s35146-019-0070-x SN - 2192-8843 VL - 80 IS - 7-8 SP - 124 EP - 129 ER - TY - GEN A1 - Vacca, Antonino A1 - Bargende, Michael A1 - Chiodi, Marco A1 - Netzer, Corinna A1 - Gern, Maike Sophie A1 - Kauf, Georg Malte A1 - Kulzer, André Casal A1 - Franken, Tim T1 - Analysis of Water Injection Strategies to Exploit the Thermodynamic Effects of Water in Gasoline Engines by Means of a 3D-CFD Virtual Test Bench N2 - CO2 emission constraints taking effect from 2020 lead to further investigations of technologies to lower knock sensitivity of gasoline engines, main limiting factor to increase engine efficiency and thus reduce fuel consumption. Moreover the RDE cycle demands for higher power operation, where fuel enrichment is needed for component protection. To achieve high efficiency, the engine should be run at stoichiometric conditions in order to have better emission control and reduce fuel consumption. Among others, water injection is a promising technology to improve engine combustion efficiency, by mainly reducing knock sensitivity and to keep high conversion rates of the TWC over the whole engine map. The comprehension of multiple thermodynamic effects of water injection through 3D-CFD simulations and their exploitation to enhance the engine combustion efficiency is the main purpose of the analysis. As basis for the research a single cylinder engine derived from a 1l turbocharged 3-cylinders engine is used to evaluate indirect and direct water injection. The entire engine flow field is reproduced and analyzed with 3D-CFD simulations and numerical models are employed to separate the influence of chemical and thermodynamic properties. Measurements are performed with different injectors for indirect/direct water injection in the single-cylinder engine in order to assess water break-up, wall wetting, spray interaction and penetration. Several injection strategies, such as varying start of injection, injection pressure, and water to fuel ratio, are tested at the single-cylinder engine test bench. Detailed gas phase chemistry is employed to link flame front speed with water concentration and knocking occurrence. These results are correlated with the 3D-CFD simulation of mixture formation, in-cylinder flow and water distribution for two different operating points (part load and maximum power) in order to study water behavior, with focus on the evaporation process, in-cylinder pressure and temperature profile, as well as the combustion development, during multiple engine cycles. KW - Water Injection KW - Computational Fluid Dynamics KW - Simulation KW - Virtual Test Bench KW - Thermodynamics Y1 - 2019 UR - https://saemobilus.sae.org/content/2019-24-0102 U6 - https://doi.org/10.4271/2019-24-0102 PB - SAE International CY - Neapel ER - TY - GEN A1 - Franken, Tim A1 - Netzer, Corinna A1 - Mauß, Fabian A1 - Pasternak, Michal A1 - Seidel, Lars A1 - Borg, Anders A1 - Lehtiniemi, Harry A1 - Matrisciano, Andrea A1 - Kulzer, André Casal T1 - Multi-objective optimization of water injection in spark-ignition engines using the stochastic reactor model with tabulated chemistry T2 - International Journal of Engine Research N2 - Water injection is investigated for turbocharged spark-ignition engines to reduce knock probability and enable higher engine efficiency. The novel approach of this work is the development of a simulation-based optimization process combining the advantages of detailed chemistry, the stochastic reactor model and genetic optimization to assess water injection. The fast running quasi-dimensional stochastic reactor model with tabulated chemistry accounts for water effects on laminar flame speed and combustion chemistry. The stochastic reactor model is coupled with the Non-dominated Sorting Genetic Algorithm to find an optimum set of operating conditions for high engine efficiency. Subsequently, the feasibility of the simulation-based optimization process is tested for a three-dimensional computational fluid dynamic numerical test case. The newly proposed optimization method predicts a trade-off between fuel efficiency and low knock probability, which highlights the present target conflict for spark-ignition engine development. Overall, the optimization shows that water injection is beneficial to decrease fuel consumption and knock probability at the same time. The application of the fast running quasi-dimensional stochastic reactor model allows to run large optimization problems with low computational costs. The incorporation with the Non-dominated Sorting Genetic Algorithm shows a well performing multi-objective optimization and an optimized set of engine operating parameters with water injection and high compression ratio is found. KW - Water Injection KW - Genetic Optimization KW - Spark Ignition Engine KW - Stochastic Reactor Model KW - Detailed Chemistry Y1 - 2019 UR - https://journals.sagepub.com/doi/full/10.1177/1468087419857602 U6 - https://doi.org/10.1177/1468087419857602 SN - 2041-3149 VL - 20 IS - 10 SP - 1089 EP - 1100 ER - TY - GEN A1 - Van Treek, Lisa A1 - Lubrano Lavadera, Marco A1 - Konnov, Alexander A. A1 - Seidel, Lars A1 - Mauß, Fabian T1 - Measurements of the laminar burning velocities of ethanol-water-air flames N2 - The laminar burning velocity of ethanol-water-air flames at atmospheric pressure and initial gas temperatures of T = 358 K was measured with the heat flux method. The mixture of ethanol-water-air contained 0%, 10%, 20%, 30% and 40% water by mole and the equivalence ratio (ϕ) range was varied from 0.7 to 1.4. The experiments were compared against predictions using three different kinetic models. Y1 - 2019 UR - https://www.researchgate.net/publication/330635016_Measurements_of_the_laminar_burning_velocities_of_ethanol-water-air_flames N1 - 1st International Conference on Smart Energy Carriers ER - TY - GEN A1 - Shrestha, Krishna Prasad A1 - Seidel, Lars A1 - Zeuch, Thomas A1 - Mauß, Fabian T1 - Modeling for Nitromethane oxidation T2 - 1st International Conference on Smart Energy Carriers Napoli, 2019 N2 - The diminishing availability of conventional fuels and stricter regulations on pollution control and CO2 emission targets have led scientist and engineers to look for alternative fuels. Recently nitromethane has slowly gained interest as alternative fuel over conventional fuel for internal combustion engines. In the past, it was mostly used as rocket propellant or as an explosives [1,2]. Nitromethane is an energetic compound with a wide variety of applications, including its use as a monopropellant, a liquid explosive, a solvent for chemical processing and analysis, and a highperformance fuel additive for internal combustion engines and pulsed detonation engines [3]. The chemical formula of nitromethane is CH3NO2. As the name suggests, the molecule is essentially methane with one of the four hydrogens replaced by a nitro group. In essence, it is the simplest of possible energetic CHON molecules that contain nitro groups, which is why it is often used in reaction studies as a prototype for more complex energetic materials. There is no reliable kinetic model for nitromethane combustion, which is validated over a wide range of experimental conditions. There are a few published studies [4–8] both numerically and experimentally focusing often on a single reactor at very specific conditions. The aim of the present work is to extend our recently published mechanism [9] for syngas, methane and ammonia oxidation to include CH3NO2 as fuel and validate against the available experimental data from the literature. The development and compilation strategy for our mechanism is described in our recent work [9] and this study is conducted in a similar manner. Rates are taken mainly from [7,10–16]. This makes the kinetic model more robust and reliable for combustion modelling. Y1 - 2019 UR - http://logesoft.com/loge-16/wp-content/uploads/2019/01/Abstract_1stICSEC_SMARTCATs_Napoli_Shrestha-et-al_2018-11-28.pdf ER - TY - GEN A1 - León, Larisa A1 - Ruwe, Lena A1 - Moshammer, Kai A1 - Seidel, Lars A1 - Shrestha, Krishna Prasad A1 - Wang, Xiaoxiao A1 - Mauß, Fabian A1 - Kohse-Höinghaus, Katharina A1 - Hansen, Nils T1 - Chemical insights into the larger sooting tendency of 2-methyl-2-butene compared to n-pentane T2 - Combustion and Flame N2 - A comprehensive, chemically detailed mechanism for the combustion of 2-methyl-2-butene and n-pentane is presented to provide insights into the different sooting tendencies of these two structurally different C5 hydrocarbons. A hierarchically assembled mechanism has been developed to specifically target speciation data from low-pressure premixed flames of 2-methyl-2-butene [Ruwe et al., Combust. Flame, 175, 34-46, 2017] and newly measured mole fraction data for a fuel-rich (ɸ=1.8) n-pentane flame, in which species profiles up to phenol were quantified. The partially isomer-resolved chemical composition of this flame was determined using flame-sampling molecular-beam mass spectrometry with single-photon ionization by tunable, synchrotron-generated vacuum-ultraviolet radiation. The presented model, which includes a newly determined, consistent set of the thermochemistry data for the C5 species, presents overall satisfactory capabilities to predict the mole fraction profiles of common combustion intermediates. The analysis of the model predictions revealed the fuel-structure dependencies (i.e. saturated vs. unsaturated and linear vs. branched) of the formation of small aromatic species that are considered as soot precursors. The propensity of the 2-methyl-2-butene flame to form larger concentrations of aromatic species was traced back to the readily available formation routes of several small precursor molecules and the efficient formation of “first aromatic rings” beyond benzene. KW - 2-Methyl-2-butene KW - n-Pentane KW - Laminar premixed flames KW - Molecular-beam mass spectrometry KW - Kinetic modeling KW - PAH formation Y1 - 2019 UR - https://www.sciencedirect.com/science/article/abs/pii/S0010218019302883#! U6 - https://doi.org/10.1016/j.combustflame.2019.06.029 SN - 0010-2180 VL - 208 SP - 182 EP - 197 ER - TY - GEN A1 - Shrestha, Krishna Prasad A1 - Seidel, Lars A1 - Zeuch, Thomas A1 - Mauß, Fabian T1 - Modeling of NOx Formation and Consumption during Oxidation of Small Alcohols T2 - 9th European Combustion Meeting, Proceedings of the European Combustion Meeting N2 - This work presents a newly developed kinetic mechanism extending our recent work (Shrestha et al. [1]) for the oxidation of methanol and ethanol and their fuel interaction with NO x chemistry in jet-stirred reactors, flow reactors, and burner-stabilized premixed flames. The work mainly focuses on fuel interaction with nitrogen chemistry and NO formation in laminar premixed flames. It is found that for methanol oxidation in jet-stirred reactor doping of the fuel blends with NO increase the reactivity of the system by increasing the net production of OH radicals. The increased amount of OH is formed via NO/NO 2 interconversion reaction channels NO+HO 2 ⇋NO 2 +OH, NO 2 +H⇋NO+OH, NO 2 +HO 2 ⇋HONO+O 2, followed by the thermal decomposition of HONO producing NO and OH. In burner-stabilized premixed flames studied here for methanol/air and ethanol/air, NO is mainly formed via the NCN route (CH+N 2 ⇋NCN+H) and minor contribution comes from the NNH route (NNN⇋N 2 +H). Y1 - 2019 UR - https://hal.archives-ouvertes.fr/hal-02334906 ER - TY - GEN A1 - Matrisciano, Andrea A1 - Netzer, Corinna A1 - Werner, Adina A1 - Borg, Anders A1 - Seidel, Lars A1 - Mauß, Fabian T1 - A Computationally Efficient Progress Variable Approach for In-Cylinder Combustion and Emissions Simulations T2 - SAE Technical Paper N2 - The use of complex reaction schemes is accompanied by high computational cost in 3D CFD simulations but is particularly important to predict pollutant emissions in internal combustion engine simulations. One solution to tackle this problem is to solve the chemistry prior the CFD run and store the chemistry information in look-up tables. The approach presented combines pre-tabulated progress variable-based source terms for auto-ignition as well as soot and NOx source terms for emission predictions. The method is coupled to the 3D CFD code CONVERGE v2.4 via user-coding and tested over various speed and load passenger-car Diesel engine conditions. This work includes the comparison between the combustion progress variable (CPV) model and the online chemistry solver in CONVERGE 2.4. Both models are compared by means of combustion and emission parameters. A detailed n-decane/α-methyl-naphthalene mechanism, comprising 189 species, is used for both online and tabulated chemistry simulations. The two chemistry solvers show very good agreement between each other and equally predict trends derived experimentally by means of engine performance parameters as well as soot and NOx engine-out emissions. The CPV model shows a factor 8 speed-up in run-time compared to the online chemistry solver without compromising the accuracy of the solution. Y1 - 2019 U6 - https://doi.org/10.4271/2019-24-0011 SN - 0148-7191 SN - 2688-3627 ER - TY - GEN A1 - Franken, Tim A1 - Duggan, Alexander A1 - Matrisciano, Andrea A1 - Lehtiniemi, Harry A1 - Borg, Anders A1 - Mauß, Fabian T1 - Multi-Objective Optimization of Fuel Consumption and NO x Emissions with Reliability Analysis Using a Stochastic Reactor Model T2 - SAE Technical Paper N2 - The introduction of a physics-based zero-dimensional stochastic reactor model combined with tabulated chemistry enables the simulation-supported development of future compression-ignited engines. The stochastic reactor model mimics mixture and temperature inhomogeneities induced by turbulence, direct injection and heat transfer. Thus, it is possible to improve the prediction of NOx emissions compared to common mean-value models. To reduce the number of designs to be evaluated during the simulation-based multi-objective optimization, genetic algorithms are proven to be an effective tool. Based on an initial set of designs, the algorithm aims to evolve the designs to find the best parameters for the given constraints and objectives. The extension by response surface models improves the prediction of the best possible Pareto Front, while the time of optimization is kept low. This work presents a novel methodology to couple the stochastic reactor model and the Non-dominated Sorting Genetic Algorithm. First, the stochastic reactor model is calibrated for 10 low, medium and high load operating points at various engine speeds. Second, each operating point is optimized to find the lowest fuel consumption and specific NOx emissions. The optimization input parameters are the temperature at intake valve closure, the compression ratio, the start of injection, the injection pressure and exhaust gas recirculation rate. Additionally, it is ensured that the maximum peak cylinder pressure and turbine inlet temperature are not exceeded. This enables a safe operation of the engine and exhaust aftertreatment system under the optimized conditions. Subsequently, a reliability analysis is performed to estimate the effect of off-nominal conditions on the objectives and constraints. The novel multi-objective optimization methodology has proven to deliver reasonable results. The zero-dimensional stochastic reactor model with tabulated chemistry is a fast running physics-based model that allow to run large optimization problems in a short amount of time. The combination with the reliability analysis also strengthens the confidence in the simulation-based optimized engine operation parameters. Y1 - 2019 U6 - https://doi.org/10.4271/2019-01-1173 SN - 0148-7191 SN - 2688-3627 ER - TY - GEN A1 - Van Treek, Lisa A1 - Lubrano Lavadera, Marco A1 - Seidel, Lars A1 - Mauß, Fabian A1 - Konnov, Alexander A. T1 - Experimental and modelling study of laminar burning velocity of aqueous ethanol T2 - Fuel N2 - Laminar burning velocities of ethanol-water-air mixtures have been determined using the heat flux method. Aqueous ethanol contained 0–40% of water by mole fraction. Laminar premixed flat flames were stabilized on a perforated burner under adiabatic conditions for the equivalence ratio range from 0.7 to 1.4. Burning velocity measurements were performed for the initial gas temperature of 358 K and at atmospheric pressure. The results for ethanol-air flames are in good agreement with the previous data obtained using the same heat flux method. The present and literature experimental data were compared against predictions using four different kinetic models. All models show uniform behaviour over the range of ethanol dilution by water covered in the present study. However, model predictions significantly diverge from the experimental data obtained in spherical flames. To quantify the effect of dilution on the laminar burning velocity, an empirical dimensionless correlation has been derived from the experimental data and predictions of the models tested. Further numerical analyses were performed to identify the effects of water addition on laminar burning velocities. Results suggested that water strongly interacts with the H2/O2 and C1 oxidation/recombination routes. Y1 - 2019 U6 - https://doi.org/10.1016/j.fuel.2019.116069 SN - 1873-7153 VL - 257 ER - TY - GEN A1 - Hilbig, Martin A1 - Malliotakis, Zisis A1 - Seidel, Lars A1 - Vourliotakis, George A1 - Keramiotis, Christos A1 - Mauß, Fabian A1 - Founti, Maria T1 - The effect of base chemistry choice in a generated n‐hexane oxidation model using an automated mechanism generator T2 - International Journal of Chemical Kinetics N2 - The present study describes the utilization of a reaction mechanism generator for the development of chemical kinetic models. The aim of the investigation is twofold. The in-house developed mechanism generator is updated with reaction classes reported in the literature, and the effect of the lower hydrocarbon chemistry, that is, base chemistry, on the generation process is assessed. For this purpose, the algorithm is implemented on two different base chemistry mechanisms, that have previously been validated against a different range of hydrocarbons, that is, the mechanisms of the groups coauthoring the study. n-Hexane has been used as a modeling target due to its important role in combustion studies as a surrogate for engine and aviation applications. The steps of the generation process are given in detail as this is the first time the current algorithm is utilized. The two generated mechanisms are compared against speciation data, ignition delay times, and flame velocities from the literature. The overall agreement of the generated mechanisms is satisfying; discrepancies exist in the negative temperature coefficient regime. Reaction path analysis and sensitivity analysis were performed, revealing the reactions that cause the different mechanism performance. Among others, the study reveals that the generated schemes pose a fast and adequate alternative to literature mechanisms; it is however evident that the latter may include more detailed reaction paths and are therefore superior in terms of validation. Y1 - 2019 U6 - https://doi.org/10.1002/kin.21309 SN - 1097-4601 SN - 0538-8066 VL - 51 IS - 10 SP - 786 EP - 798 ER -