@misc{GernKaufVaccaetal., author = {Gern, Maike Sophie and Kauf, Georg Malte and Vacca, Antonino and Franken, Tim and Kulzer, Andr{\´e} Casal}, title = {Ganzheitliche Methode zur Bewertung der Wassereinspritzung}, series = {MTZ - Motortechnische Zeitschrift}, volume = {80}, journal = {MTZ - Motortechnische Zeitschrift}, number = {7-8}, issn = {2192-8843}, doi = {10.1007/s35146-019-0070-x}, pages = {124 -- 129}, abstract = {Die k{\"u}nftige Effizienzsteigerung bei Ottomotoren mit Direkteinspritzung sowie die Reduktion von gas- und partikelf{\"o}rmigen Emissionen erfordern innovative Ans{\"a}tze. Durch die neue RDEGesetzgebung f{\"u}r 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 f{\"u}hrt zu einem effizienten Betrieb, der jedoch durch das Risiko irregul{\"a}rer Verbrennung und hohen Abgastemperaturen limitiert ist. Durch den Einsatz von Wassereinspritzung k{\"o}nnen sowohl die Klopfneigung als auch die Abgastemperatur reduziert werden, was den Schutz der Abgasnachbehandlungskomponenten bei gleichzeitiger Wirkungsgradsteigerung erm{\"o}glicht. 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.}, language = {de} } @misc{VaccaBargendeChiodietal., author = {Vacca, Antonino and Bargende, Michael and Chiodi, Marco and Netzer, Corinna and Gern, Maike Sophie and Kauf, Georg Malte and Kulzer, Andr{\´e} Casal and Franken, Tim}, title = {Analysis of Water Injection Strategies to Exploit the Thermodynamic Effects of Water in Gasoline Engines by Means of a 3D-CFD Virtual Test Bench}, publisher = {SAE International}, address = {Neapel}, doi = {10.4271/2019-24-0102}, abstract = {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.}, language = {en} } @misc{FrankenMaussSeideletal., author = {Franken, Tim and Mauß, Fabian and Seidel, Lars and Gern, Maike Sophie and Kauf, Malte and Matrisciano, Andrea and Kulzer, Andre Casal}, title = {Gasoline engine performance simulation of water injection and low-pressure exhaust gas recirculation using tabulated chemistry}, series = {International Journal of Engine Research}, volume = {21}, journal = {International Journal of Engine Research}, number = {10}, issn = {2041-3149}, doi = {10.1177/1468087420933124}, pages = {1857 -- 1877}, abstract = {This work presents the assessment of direct water injection in spark-ignition engines using single cylinder experiments and tabulated chemistry-based simulations. In addition, direct water injection is compared with cooled low-pressure exhaust gas recirculation at full load operation. The analysis of the two knock suppressing and exhaust gas cooling methods is performed using the quasi-dimensional stochastic reactor model with a novel dual fuel tabulated chemistry model. To evaluate the characteristics of the autoignition in the end gas, the detonation diagram developed by Bradley and coworkers is applied. The single cylinder experiments with direct water injection outline the decreasing carbon monoxide emissions with increasing water content, while the nitrogen oxide emissions indicate only a minor decrease. The simulation results show that the engine can be operated at l = 1 at full load using water-fuel ratios of up to 60\% or cooled low-pressure exhaust gas recirculation rates of up to 30\%. Both technologies enable the reduction of the knock probability and the decrease in the catalyst inlet temperature to protect the aftertreatment system components. The strongest exhaust temperature reduction is found with cooled low-pressure exhaust gas recirculation. With stoichiometric air-fuel ratio and water injection, the indicated efficiency is improved to 40\% and the carbon monoxide emissions are reduced. The nitrogen oxide concentrations are increased compared to the fuel-rich base operating conditions and the nitrogen oxide emissions decrease with higher water content. With stoichiometric air-fuel ratio and exhaust gas recirculation, the indicated efficiency is improved to 43\% and the carbon monoxide emissions are decreased. Increasing the exhaust gas recirculation rate to 30\% drops the nitrogen oxide emissions below the concentrations of the fuel-rich base operating conditions.}, language = {en} }