@article{GeilfussDawoud, author = {Geilfuß, Kristina and Dawoud, Belal}, title = {Analytical investigation of a zeolite-NaY-water adsorption heat and cold storage and its integration into a steam power process}, series = {Energy}, volume = {195}, journal = {Energy}, number = {March}, publisher = {Elsevier}, doi = {10.1016/j.energy.2020.116977}, abstract = {tabilizing the effects of greenhouse gas emissions on the atmosphere is a key step towards solving the global climate change problems. Storage technologies play an essential role in compensating the discrepancy between surplus energy and peak times. Sorption processes, in particular, offer an environment friendly way for almost loss-free heat (of adsorption or absorption) and cold storage. This work is dedicated first to analytically investigate the potential of applying NaY-Water/Zeolite as a working pair for heat and cold storage upon utilizing high temperature heat. It turned out that, the mass of the adsorber heat exchanger increases the useful specific heat stored from 229 kWh/tzeolite for the ideal storage to 538 kWh/tzeolite or even higher depending on the thermal capacity of the adsorber heat exchanger (AdsHX). Contrary to that trend, COP will decrease with increasing the thermal capacity of the AdsHX. Sensible heat losses between charging and discharging phases do have a negative effect on both stored heating capacity and COP. In addition, an innovative hybrid steam power cum adsorption storage process is introduced and analytically investigated at different ambient conditions and time scenarios for on-peak and off-peak durations over the day. The introduced hybrid process seems quite promising in achieving electrical power production and efficiency enhancements during peak load durations. The extent of enhancing both performance indicators increases with increasing the ambient temperature difference between peak and off-peak times.}, language = {en} } @misc{SchrollDecker, author = {Schroll-Decker, Irmgard}, title = {Rezension zu: Ethik des Wissens. Freiheit und Verantwortung der Wissenschaft in Zeiten des Klimawandels. oekom Verlag (M{\"u}nchen) 2019. ISBN 978-3-96238-163-9}, series = {socialnet Rezensionen}, journal = {socialnet Rezensionen}, issn = {2190-9245}, language = {de} } @article{SnarskiiShamoninChamonineYuskevich, author = {Snarskii, Andrei A. and Shamonin (Chamonine), Mikhail and Yuskevich, Pavel}, title = {Effective medium theory for the elastic properties of composite materials with various percolation thresholds}, series = {Materials}, volume = {13}, journal = {Materials}, number = {5}, publisher = {MPDI}, address = {Basel}, doi = {10.3390/ma13051243}, pages = {1 -- 19}, abstract = {It is discussed that the classical effective medium theory for the elastic properties of random heterogeneous materials is not congruous with the effective medium theory for the electrical conductivity. In particular, when describing the elastic and electro-conductive properties of a strongly inhomogeneous two-phase composite material, the steep rise of effective parameters occurs at different concentrations. To achieve the logical concordance between the cross-property relations, a modification of the effective medium theory of the elastic properties is introduced. It is shown that the qualitative conclusions of the theory do not change, while a possibility of describing a broader class of composite materials with various percolation thresholds arises. It is determined under what conditions there is an elasticity theory analogue of the Dykhne formula for the effective conductivity. The theoretical results are supported by known experiments and show improvement over the existing approach. The introduction of the theory with the variable percolation threshold paves the way for describing the magnetorheological properties of magnetoactive elastomers. A similar approach has been recently used for the description of magneto-dielectric and magnetic properties.}, language = {en} } @inproceedings{SchiedermeierRettnerSteineretal., author = {Schiedermeier, Maximilian and Rettner, Cornelius and Steiner, Marcel and M{\"a}rz, Martin}, title = {Dual-inverter control synchronization strategy to minimize the DC-link capacitor current}, series = {2020 IEEE Vehicle Power and Propulsion Conference (VPPC), 18 November 2020 - 16 December 2020, Gijon, Spain}, booktitle = {2020 IEEE Vehicle Power and Propulsion Conference (VPPC), 18 November 2020 - 16 December 2020, Gijon, Spain}, publisher = {IEEE}, doi = {10.1109/VPPC49601.2020.9330921}, pages = {1 -- 6}, abstract = {This paper proposes the possible switching synchronization strategies of an automotive dual-inverter against the background of minimizing the RMS DC-link capacitor current. The publication mainly focuses on the straight-ahead motion of a rear axle with one electric drive per wheel. In addition to it, a dual-inverter consisting of two subinverters with a common DC-link capacitor is taken into consideration. These sub-inverters each have three phases and are based on a 2-level voltage-source-topology. To control the electrical machines, the continuous Space-Vector-Modulation strategy is used. For this application, different control signal synchronization strategies of the two sub-inverters of the dualinverter are presented. Apart from the existing strategies, this paper proposes a new method, which inherits a compromise between low complexity and high effectiveness. In contrast to previous publications, the resulting capacitor currents are quantified and subsequentlyevaluated. This novel quantification, which is dependent on the dual-inverter's operating point, provides a base for targeted dimensioning of the capacitor. Moreover, this forms the foundation for further investigations of vehicle's cornering, as well as for the possible synchronization of stand-alone inverters. In the context of this publication, the presented results are verified by experimentally determined data of a motor-inverter system.}, language = {en} } @article{BruniMeijaardRilletal., author = {Bruni, S. and Meijaard, J. P. and Rill, Georg and Schwab, A. L.}, title = {State-of-the-art and challenges of railway and road vehicle dynamics with multibody dynamics approaches}, series = {Multibody System Dynamics}, volume = {49}, journal = {Multibody System Dynamics}, number = {1}, publisher = {Springer}, doi = {10.1007/s11044-020-09735-z}, pages = {1 -- 32}, abstract = {A review of the current use of multibody dynamics methods in the analysis of the dynamics of vehicles is given. Railway vehicle dynamics as well as road vehicle dynamics are considered, where for the latter the dynamics of cars and trucks and the dynamics of single-track vehicles, in particular motorcycles and bicycles, are reviewed. Commonalities and differences are shown, and open questions and challenges are given as directions for further research in this field.}, language = {en} } @article{SchulzSchwarz, author = {Schulz, Carsten and Schwarz, Colin}, title = {Drivetrain fatigue strength characteristics of model-predictive control for wind turbines}, series = {Wind Energy}, volume = {23}, journal = {Wind Energy}, number = {12}, publisher = {Wiley}, doi = {10.1002/we.2520}, pages = {2137 -- 2149}, abstract = {Wind turbines play a crucial role in the revolution towards renewable resources. They need to be economically competitive to be sustainable. This still requires to lower the cost of energy (COE). To this end, nonlinear model predictive control (NMPC) is used within this paper. As known from literature, NMPC significantly improves the energy extracting performance as well as the mitigation of tower loads of wind turbines. As it is shown in this paper, the drivetrain fatigue strength drops disproportionally in parallel, which either increases the demands on the turbine design or decreases the lifetime of drivetrain components. Without additional boundary conditions to the underlying optimal control problems (OCPs), the application of energy-maximizing NMPC might so even raise the COE. Only penalizing axial torque oscillations by quadratic terms decreases energy-extracting performance below the level of classical wind turbine controllers. This makes more sophisticated conditions necessary. In this paper, the increase of the drivetrain damage by NMPC is analyzed, and appropriate boundary conditions are derived, to balance the two contradicting objectives of energy maximization and drivetrain load mitigation. An NMPC approach based on indirect methods is used, to obtain a solution of the OCPs very efficiently. It applies the Hamilton equations and Pontryagin's maximum principle. Its accuracy and efficiency to solve OCPs was presented over the last decades.}, language = {en} } @book{AltmannGebhardEmbergeretal., author = {Altmann, Robert and Gebhard, J{\"u}rgen and Emberger, Peter and Thuneke, Klaus and Rabl, Hans-Peter and Remmele, Edgar}, title = {Z{\"u}nd- und Brennverhalten von Pflanzen{\"o}lkraftstoff und {\"U}bertragung auf einen Motor der Abgasstufe V}, volume = {69}, publisher = {Technologie- und F{\"o}rderzentrum im Kompetenzzentrum f{\"u}r Nachwachsende Rohstoffe}, address = {Straubing}, issn = {1614-1008}, pages = {188}, abstract = {Durch den Ersatz von Dieselkraftstoff durch Raps{\"o}lkraftstoff (R100) k{\"o}nnen Treibhausgasemissionen reduziert werden. F{\"u}r einen st{\"o}rungsfreien Betrieb eines Motors mit Raps{\"o}lkraftstoff sind jedoch Modifikationen an Motorkomponenten und Motorsteuerger{\"a}t notwendig, um eine effiziente Verbrennung im Motor zu erreichen. Ziel des Vorhabens ist die Erarbeitung von Grundlagen zur Auslegung der Motorsteuerung pflanzen{\"o}ltauglicher Offroad-Motoren mit moderner Abgasnachbehandlung mit anschließender entsprechender Abstimmung der Motorapplikation am Pr{\"u}fstand. Grundlegende Untersuchungen der physikalischen Prozessabl{\"a}ufe von R100 bei der Einspritzung werden an einem hydraulischen Druckanstiegsanalysator (HDA) und einer Hochdruck-Hochtemperatur-Kammer (HDHT-Kammer) durchgef{\"u}hrt. Unterschiede im Z{\"u}nd- und Brennverhalten werden in einer Konstantvolumenbrennkammer untersucht. Abschließend werden die Erkenntnisse am Motorenpr{\"u}fstand auf einen DEUTZ-Motor {\"u}bertragen, dessen Einspritzsystem auch bei den grundlegenden Untersuchungen verwendet wurde. Die Ergebnisse zeigen, dass das Einspritzverhalten von R100 eine h{\"o}here Sensitivit{\"a}t gegen{\"u}ber Kraftstofftemperaturvariationen aufweist als Dieselkraftstoff. Bei niedrigen raftstofftemperaturen sind mit R100 ein l{\"a}ngerer {\"O}ffnungsverzug und eine geringere Einspritzmenge festzustellen. Um diesen Einfluss bei der Einspritzstrategie zu kompensieren, ist die Kenntnis der Kraftstofftemperatur im Injektor notwendig. Eine weitere Herausforderung stellt die Gemischaufbereitung dar, hier f{\"u}hren unter anderem die h{\"o}here Viskosit{\"a}t und h{\"o}here Siedetemperaturen von R100 zu einem schm{\"a}leren Spritzwinkel und verz{\"o}gerter Verdampfung im Vergleich zum Dieselkraftstoff. Eine Erh{\"o}hung des Einspritzdrucks und h{\"o}here Temperaturen und Dr{\"u}cke in der Brennkammer verbessern die Gemischaufbereitung. Bei Bedingungen von mittlerer und hoher Last ist der Z{\"u}ndverzug von R100 k{\"u}rzer und das Verbrennungsverhalten {\"a}hnlich zum Dieselkraftstoff. Eine geringere W{\"a}rmefreisetzung von R100 wird durch den geringeren Heizwert verursacht. Unter Bedingungen von niedriger Last und Motorstart ist ein l{\"a}ngerer Z{\"u}ndverzug von R100 im Vergleich zum Dieselkraftstoff festzustellen. Eine Steigerung des Einspritzdrucks und h{\"o}here Brennkammerdr{\"u}cke und -temperaturen f{\"u}hren bei beiden Kraftstoffen zu k{\"u}rzeren Z{\"u}ndverz{\"u}gen, der Einfluss dieser Parameter ist jedoch f{\"u}r R100 st{\"a}rker als f{\"u}r Dieselkraftstoff. Voreinspritzungen f{\"u}hren bei beiden Kraftstoffen zu einer Verk{\"u}rzung des Z{\"u}ndverzugs der Haupteinspritzung und zu einer geringeren W{\"a}rmefreisetzungsrate. Am Motorpr{\"u}fstand ist bei gleicher Motorapplikation mit R100 eine geringere Leistung als mit Dieselkraftstoff festzustellen. Nach Angleichung der Motorleistung durch Anhebung der Einspritzmenge von R100 sind im Rohabgas Stickstoffoxid (NOX)- und Kohlenstoffmonoxidemissionen auf gleichem Niveau zu Dieselkraftstoff zu beobachten sowie geringere Partikelemissionen. Unter Verwendung eines DoE Vorgehens kann der Partikel-NOX - trade-off von R100 optimiert und Einstellparameter gefunden werden, in denen sowohl niedrigere NOX als auch niedrigere Partikelemissionen im Vergleich zum Dieselkraftstoff resultieren. Das installierte Abgasnachbehandlungssystem, bestehend aus einem Dieseloxidationskatalysator (DOC), Dieselpartikelfilter (DPF) und selektivem katalytischem Reduktionssystem (SCR), arbeitet f{\"u}r beide Kraftstoffe {\"a}hnlich und es scheint keine Anpassung der Dosierungsstrategie der w{\"a}ssrigen Harnstoffl{\"o}sung notwendig zu sein. Eine Regeneration des Partikelfilters mit R100 war nach Optimierung der Einstellparameter der Drosselklappe m{\"o}glich. Motorkaltstart und Leerlauf sind herausfordernde Betriebsphasen, die f{\"u}r R100 einer weiteren Optimierung bed{\"u}rfen. Eine Temperierung von R100 im Injektor auf 50-60 °C sowie eine Kompensation der Einspritzmenge in Abh{\"a}ngigkeit von der Kraftstofftemperatur sind m{\"o}gliche Verbesserungsmaßnahmen. Zudem kann durch einen fr{\"u}heren Einspritzbeginn von R100 das Verbrennungsverhalten angepasst werden. Die Motorpr{\"u}fstandsuntersuchungen best{\"a}tigen qualitativ die Erkenntnisse die mit dem hydraulischen Druckanstiegsanalysator (HDA), der Hochdruck-Hochtemperatur-Kammer (HDHT-Kammer) und der Konstantvolumenbrennkammer gewonnen wurden. Weitere Untersuchungen sind notwendig, um die Ergebnisse auf einen baugleichen, in einer mobilen Arbeitsmaschine eingebauten Motor zu transferieren, damit Informationen zur Dauerhaltbarkeit unter realen Bedingungen erhalten werden k{\"o}nnen. Weiterf{\"u}hrende Forschungsarbeiten sind im Bereich der Betriebsphasen des Motorkaltstarts und Leerlaufs mit Raps{\"o}lkraftstoff n{\"o}tig, um einen dauerhaft st{\"o}rungsfreien Betrieb in diesen Betriebsphasen zu erreichen. Die erzielten Erkenntnisse deuten darauf hin, dass hier noch viel Verbesserungspotenzial vorhanden ist.}, subject = {Biokraftstoff}, language = {de} } @inproceedings{HopfenspergerDaubnerHerrmannetal., author = {Hopfensperger, Bernhard and Daubner, Andreas and Herrmann, Fabian and Hopkins, Andrew and Mellor, Phil}, title = {Investigation of Shifted PWM Methods for a Dual Three-Phase System to Reduce Capacitor RMS Current}, series = {PCIM Europe Digital Days 2020: International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management: 07.-08.07.2020, Online [proceedings]}, booktitle = {PCIM Europe Digital Days 2020: International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management: 07.-08.07.2020, Online [proceedings]}, publisher = {VDE-Verlag}, address = {Berlin, Offenbach}, isbn = {978-3-8007-5245-4}, pages = {124 -- 131}, abstract = {Mild hybrid automotive topologies containing a 48V high power (>15 kW) electric drive system demand a high integration of power electronics and electrical machine. A multi-phase motor winding topology helps to keep the per-phase operating currents to a reasonable level. Close integration and multi-phase system have led to a drive system with dual 3-phase systems supplied by a common 48V DC-link, which allows to shift PWM patterns for reduction of DC-link capacitor ripple current and size. This paper derives some basic rules for combinations of common PWM methods for dual 3-phase systems without magnetic cross-coupling. Experimental measurements verify simulated results.}, subject = {Elektroantrieb}, language = {en} } @inproceedings{KetterlHeinrichReitmeieretal., author = {Ketterl, Hermann and Heinrich, Tobias and Reitmeier, Torsten and Hoelscher, Clemens}, title = {Emissionsabh{\"a}ngige Leistungsregelung f{\"u}r BHKW's}, series = {Tagungsband AALE 2020: Automatisierung und Mensch-Technik-Interaktion, 17. Fachkonferenz, 4. bis 6. M{\"a}rz 2020, Leipzig}, volume = {2020}, booktitle = {Tagungsband AALE 2020: Automatisierung und Mensch-Technik-Interaktion, 17. Fachkonferenz, 4. bis 6. M{\"a}rz 2020, Leipzig}, editor = {J{\"a}kel, Jens and Thiel, Robert}, publisher = {VDE-Verlag}, isbn = {978-3-8007-5180-8}, pages = {7}, language = {de} } @misc{SchwanzerMieslingerRabletal., author = {Schwanzer, Peter and Mieslinger, Johann and Rabl, Hans-Peter and Dietrich, Markus and Haft, Gerhard and Walter, Stefanie and Hagen, Gunter and Moos, Ralf and Gaderer, Matthias}, title = {Monitoring of a Particulate Filter for Gasoline Direct Injection Engines with a Radio-Frequency-Sensor}, series = {11th International Exhaust Gas and Particulate Emissions Forum, 3.-4.3.2020, Ludwigsburg, Germany}, journal = {11th International Exhaust Gas and Particulate Emissions Forum, 3.-4.3.2020, Ludwigsburg, Germany}, abstract = {In order to comply with future emission regulations, the use of particulate filters in vehicles with direct injection gasoline engines is essential. The current amount of soot and ash in the filter is calculated by a soot load model in the electronic control unit in combination with a differential pressure sensor determining the pressure drop over the particulate filter. Active regeneration is initiated if the calculated amount of soot or the measured differential pressure is too high. This is associated with additional fuel consumption. An on-board diagnosis for the particulate filter is currently not part of the Euro 6d emission standard. For future exhaust emission standards, on-board diagnosis or active monitoring of the particulate filter is conceivable. One of the benefits of monitoring is the fact that unnecessary active regenerations can be avoided. As a result, there is no additional fuel consumption due to misinterpretations of the amount of soot in the filter. For active monitoring of the particulate filter, a radiofrequency (RF-) sensor, that detects the soot loading of the filter with electromagnetic waves directly, can be used. Such a system has the advantage that by utilizing the filter as a sensor more precise information about the current state of the filter, e.g. a possible damage, can be provided. Worst-case considerations of filter damages, tested at an engine test bench show the advantages which are entailed by a system like that. By means of partial regeneration of the particulate filter it is demonstrated how the remaining amount of soot in the filter can be detected in a better way in comparison to the differential pressure sensor by using the RF-sensor.}, language = {en} }