@inproceedings{UntheimGrossmannTatucuErteletal.2023, author = {Untheim, Thomas and Großmann, Fabian and Tatucu-Ertel, Paul and Jochem, Marius and Weigand, Peter and Bikas, Georgios}, title = {Experimental Study on Ammonia/OME Combustion in a Dual-Fuel Engine with Emphasis on Highly Diluted Intake Air Conditions}, series = {SAE Technical Paper Series}, booktitle = {SAE Technical Paper Series}, publisher = {SAE International}, address = {400 Commonwealth Drive, Warrendale, PA, United States}, issn = {0148-7191}, doi = {10.4271/2023-01-0283}, pages = {29}, year = {2023}, abstract = {\<div class="section abstract"\<div class="htmlview paragraph"Ammonia, which is considered as an excellent hydrogen carrier, could potentially become a clean fuel for direct use in ICE.\</div\<div class="htmlview paragraph"An experimental setup with a strongly modified inline four-cylinder (I4) heavy duty Diesel engine was used to study different combustion modes of ammonia in ICE. The fourth cylinder of that engine was operated in a monovalent mode using either OME or Diesel fuel. Its complete exhaust stream was fed into the first cylinder of the same engine, which was operated on a dual-fuel mode by utilizing ammonia port injection and OME or Diesel pilot injection to ignite the mixture. The fourth cylinder of the I4 heavy duty engine can be operated at conditions between idle and full load and at different stoichiometries (λ) to impact both the temperature and the oxygen concentration at the exhaust of that cylinder. Since the first cylinder is fed by the complete exhaust stream of the fourth, the intake conditions of the first cylinder can be controlled appropriately and various ammonia combustion modes can be realized.\</div\<div class="htmlview paragraph"Emissions measurements at the intake and the exhaust of the first cylinder at different speeds and loads show the impact of the different combustion modes, especially due to temperature and oxygen content variations, on NOx and combustion efficiency. Chemical kinetics calculations have been elaborated to explain some of the main observations.\</div\</div}, language = {en} } @inproceedings{BekkingPutsSpilleretal.2023, author = {Bekking, Pim and Puts, Godfried and Spiller, Martin and Bikas, Georgios}, title = {The Be-Rex Engine-Generator}, series = {SAE Technical Paper Series}, booktitle = {SAE Technical Paper Series}, publisher = {SAE International}, address = {400 Commonwealth Drive, Warrendale, PA, United States}, issn = {0148-7191}, doi = {10.4271/2023-01-0399}, pages = {12}, year = {2023}, abstract = {Although electricity is necessary for a country's economic development, many countries lack suitable grid infrastructure. Portable generators offer a consistent electric supply in the event of a blackout. Be-Rex B.V. develops and already assembled a revolutionary engine-generator prototype. It eliminates the use of camshafts, crankshafts and flywheels while integrating the generator parts into the same spherical housing. Thus, it constitutes a compact, lightweight and cost-efficient singular unit. There is no mechanical power output while the load of the engine is determined by the demanded load of the generator. The four combustion chambers are arranged in pairs on the north and south hemisphere and the magnets of the stator are placed circumferential at the equator of the spherical housing. The rotating disc and the joiner build the rotor of the generator. While developing the engine special emphasis has been put on its multi-fuel capability. Optimized gas exchange together with an efficient scavenging concept and the combustion system allow the atmospheric version of the prototype with a displacement volume of 400 cc to achieve 10 bar of indicated mean effective pressure (imep) when running on gasoline. Using 1-D WAVE simulations the same atmospheric version converted to ammonia fuel achieves 8 bar of imep. First firing results of an engine generator prototype running on gasoline solidify the proof of concept. In the design section the main characteristics of the concept will be highlighted and the working principle will be explained. In the modelling approach section the methodology to tackle the leakage and the friction issues will be presented before the main results of the final design optimization will be discussed. Afterwards, the first experimental runs will be analyzed and finally some possible applications will be addressed.}, language = {en} } @article{GrossmannMuehlpfordtRambacheretal.2021, author = {Großmann, Fabian and M{\"u}hlpfordt, Torsten and Rambacher, Patrick and Bikas, Georgios}, title = {Crank-Angle Resolved Flow Measurements in the Intake Duct of a Research Engine Using Novel and Fast Response Aerodynamic Probes}, series = {Frontiers in Mechanical Engineering}, volume = {7}, journal = {Frontiers in Mechanical Engineering}, publisher = {Frontiers Media SA}, issn = {2297-3079}, doi = {10.3389/fmech.2021.633690}, pages = {1 -- 15}, year = {2021}, abstract = {Despite the public debate nowadays on the future of Internal Combustion Engines (ICE), which is impeding their development, one limitation towards further optimization of ICE in terms of fuel consumption and emissions can be seen in the current approach and more specifically in the transient engine operation and its control. The main drawbacks in the current approach source from: 1) complex structure of mechanization including sensors and actuators, 2) low time resolution and accuracy of sensing (cost driven), 3) complex Electronic Control Unit (ECU)-software architecture associated with huge calibration effort and 4) recently, funded research due to unsecure business model of ICE is becoming less. To overcome these difficulties unexploited potential should be utilized. Some of this potential lies in cycle-by-cycle and cylinder-by-cylinder accurate fuel and air control, and in the development of physical based virtual sensors with high time resolution and accuracy. One of the main motivations for this study was to develop a measurement technique that enables crank-angle resolved air mass flow rate measurements during engine operation in a dynamometer test cell. The measurement principle is quite simple and is based on gauging the dynamic pressure in both the intake and exhaust duct at the closest possible positions to the valves. To fulfill these requirements aerodynamic probes have been developed and manufactured utilizing 3D printing. The probes have been integrated in special developed flanges, which correspond exactly to the shape of the air channels in the cylinder head of the engine. Hence, they can be mounted either in front of the valves at the intake or behind the valves at the exhaust duct. Results at different engine operating conditions have been obtained, analyzed and correlated to other sensors like air-flow meter. Those post-processed results can be further used to validate 1-D gas exchange models, or 3-D Computational Fluid Dynamics (CFD) port flow models. The ultimate scope of these measurements is to calibrate fast physical-based gas exchange models that can be directly used in the engine control framework on an embedded system.}, language = {en} } @article{MichosBikas2020, author = {Michos, Konstantinos N. and Bikas, Georgios}, title = {Quasi-Dimensional Multi-Zone Combustion Diagnostic Tool for SI Engines with Novel NOx and CO Emissions Models}, series = {SAE International Journal of Advances and Current Practices in Mobility}, volume = {2}, journal = {SAE International Journal of Advances and Current Practices in Mobility}, number = {4}, publisher = {SAE International}, issn = {2641-9645}, doi = {10.4271/2020-01-0289}, pages = {1818 -- 1848}, year = {2020}, abstract = {In this work a quasi-dimensional multi-zone combustion diagnostic tool for homogeneous charge Spark Ignition (SI) engines is analytically developed for the evaluation of heat release, flame propagation, combustion velocities as well as engine-out NOx and CO emissions, based on in-cylinder pressure data analysis. The tool can be used to assess the effects of fuel, design and operating parameters on the SI engine combustion and NOx and CO emissions formation processes. "Certain novel features are included in the presently developed combustion diagnostic tool. Firstly, combustion chambers of any shape and spark plug position can be considered due to an advanced model for the calculation of the geometric interaction between a spherically expanding flame and a general combustion chamber geometry. Also, the temperature stratification of the burned gas developed during the combustion phase, which has to be captured for the theoretically realistic estimation of the in-cylinder formation of pollutant emissions, is taken into account by a multi-zone thermodynamic treatment. According to this, multiple spherically allocated burned zones are sequentially generated at specified (user-defined) crank angle intervals, forming overlapping shells. Moreover, complex chemical equilibrium compositions are computed, which can include any user-defined mixture of species in the combustion products, using an advanced modular method based on the minimization of Gibbs energy. Furthermore, NOx and CO engine-out emissions are calculated based on novel in-cylinder formation models presented by the authors in the past. Specifically, NOx emissions are evaluated by a global algebraic NOx emissions formation model, accounting for both thermal and subO pathway NO formation, based on the calculation of the characteristic timescales of the relevant NO formation mechanisms. CO emissions are assessed using a new kinetics-based model, consisting of a single Ordinary Differential Equation (ODE) that can be analytically integrated. The CO emissions model is derived considering the dynamics of a representative pool of active radicals in post-flame gases and explicitly describes the CO oxidation quenching process. "The combustion diagnostic tool is applied to a lean burn gas engine at various engine speeds under full load conditions and constant lambda value. Various combustion and NOx and CO emissions related results are presented and discussed to illustrate the capabilities of the tool for combustion diagnosis, while at the same time calculated engine-out NOx and CO emissions are found to be in satisfactory agreement with measured ones.}, language = {en} } @inproceedings{BikasWeigandBrilzetal.2020, author = {Bikas, Georgios and Weigand, Peter and Brilz, Marina and Michos, Konstantinos}, title = {High Resolution Global NOx Sub-Model for Embedded System Application with Low Calibration Effort}, series = {SAE Technical Paper Series}, booktitle = {SAE Technical Paper Series}, publisher = {SAE International}, address = {400 Commonwealth Drive, Warrendale, PA, United States}, issn = {0148-7191}, doi = {10.4271/2020-01-0246}, year = {2020}, language = {en} } @article{PohlCarstensenAufleger2022, author = {Pohl, Reinhard and Carstensen, Dirk and Aufleger, Markus}, title = {Verbleibendes Risiko und Notfallpl{\"a}ne f{\"u}r Talsperren, Hochwasserr{\"u}ckhalte- und Speicherbecken}, series = {Wasserwirtschaft}, volume = {112}, journal = {Wasserwirtschaft}, number = {9}, publisher = {Springer Science and Business Media LLC}, issn = {0043-0978}, doi = {10.1007/s35147-022-1113-7}, pages = {12 -- 19}, year = {2022}, language = {de} } @article{Carstensen2021, author = {Carstensen, Dirk}, title = {Talsperren - elementare Bauwerke zur Sicherung unserer Zukunft}, series = {Wasserwirtschaft}, volume = {111}, journal = {Wasserwirtschaft}, number = {9/10}, publisher = {Springer Science and Business Media LLC}, issn = {0043-0978}, doi = {10.1007/s35147-021-0904-6}, pages = {94 -- 95}, year = {2021}, language = {de} }