@misc{Katzer, author = {Katzer, Christian}, title = {Bedarf an Verbrennungsforschung f{\"u}r Braunkohlekraftwerke - Am Beispiel des Lehrstuhl Kraftwerkstechnik der BTU Cottbus- Senftenberg}, series = {VGB PowerTech}, volume = {98}, journal = {VGB PowerTech}, number = {8}, issn = {1435-3199}, pages = {58 -- 64}, abstract = {From its foundation of the chair of power plant technology at Brandenburg University of Technology Cottbus - Senftenberg, the combustion research has engaged with current issues of conventional power plant technology. The focus of his research activity was starting from development of technology to maximize the efficiency, switched to the new research field of oxyfuel technologies and working currently on questions about operational flexibility as reaction of changes in the current energy sector. There are many concepts for increasing plant flexibility, but without optimization of flame monitoring and re-evaluation of existing limits, this potential for optimization can't be sufficiently used. The current research project to increasing thermal plant flexibility of existing coal-fired power plants is implementing the necessity for analysis and optimization research. Therefore, one goal is a significant progress in the evaluation of cyclic operation with higher load transients and load cycles of coal-fired power plants. Furthermore, a research evaluation about the effects on the components life of components of the water-steam cycle is possible.}, language = {de} } @misc{MieckKrautz, author = {Mieck, Sebastian and Krautz, Hans Joachim}, title = {Systematic analysis and preparation of high resolution in-situ measurements for the estimation of PV module parameters}, series = {VGB PowerTech}, volume = {98}, journal = {VGB PowerTech}, number = {8}, issn = {1435-3199}, pages = {75 -- 81}, abstract = {In the last two decades, a rapid expansion of photovoltaic (PV) power plants of different sizes has taken place. Along with this, the interest from science and industry is growing, exploring the strengths and weaknesses of this technology as well as further developing the efficiency in its production and operation. For planning and operating of PV power plants, valid energy yield forecasts are desirable. These forecasts are also important to draw conclusions for the monitoring of future PV technologies. The analysis, evaluation and processing of meteorological and technical measurement datasets play an essential role. In this article, high-resolution measurement data sets of a mobile, autarkic test system are analyzed firstly. The measured data are checked for plausibility and validity with the corresponding methods. After this observations and phenomena with meteorological cause are described. In a second step, a practicable procedure for the preparation of the measurement data is presented, in order to make it suitable for further calculations, e.g. identification of photovoltaic module parameters for energy yield calculations. The focus is particularly on the flexibility, adaptability and code performance of the processing procedure. Results, evaluations and outlooks on the methods used, measurement data and selected software packages are made.}, language = {en} } @phdthesis{Ojong, author = {Ojong, Emile Tabu}, title = {Characterization of the Performance of PEM Water Electrolysis Cells operating with and without Flow Channels, based on Experimentally Validated Semi-empirical Coupled-Physics Models}, address = {Cottbus ; Senftenberg}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus4-46504}, pages = {XXV, 146}, abstract = {PEM water electrolysis is a clean and efficient conversion technology for hydrogen production and energy storage, especially when coupled with renewable energy sources. In spite of its many advantages, the high component and cell manufacturing costs of the conventional PEM electrolysis cell makes the PEM water electrolysis technology commercially less competitive vis-{\`a}-vis its peers. An alternative and cost effective cell design has been proposed which has up to a 25 \% costs advantage over the conventional cell. In this alternative cell design, the flow channel plate which bears the most material costs in the conventional cell design has been replaced with a 3-D Porous Transport Layer (PTL) structure. While both designs perform comparably the same at low to mid current density (0 - 2 A/cm²), it has been observed that the conventional cell by far out performs the low cost cell at high current density operations, due to increased mass transport limitation in the cell without flow channels. Since industrial and commercial hydrogen production efforts are focused towards high current density operation (> 3 A/cm²), it thus becomes obvious that, in order for the cost effective alternative cell design to establish itself over the conventional cell design, the mass transport issues at high current densities have to be well understood and described. This research work seeks to understand the source of, and to eliminate the mass transport losses in the cost effective alternative cell design in order to get it performing at least as good as the conventional cell design at current densities up to 5 A/cm². To meet this objective, 2-D non-isothermal semi-empirical fully-coupled models of both cell designs have been developed and experimentally validated. The developed validated models were then used as tools to simulate and predict the best operating conditions, design parameters and micro-structural properties of the PTL at which the mass transport issues in the design without flow channels will be at its minimum, so that both cells can exhibit comparable performance even at high current densities. The models developed in this work are based on a multi-physics approach in which thermodynamic, electrochemical, thermal and mass transport sub-models are coupled and solved numerically, to predict the cell polarization and individual overpotentials, as well as address heat and water management issues. The most unique aspect of this work however, is the development of own semi-empirical equations for predicting the mass transport overpotential imposed by the gas phase (bubbles) at high current densities. Also, for the very first time, calculated PEM water electrolysis polarization curves up to 5 A/cm² have been validated by own experimental data. The results show that, the operating temperature and pressure, inlet water flowrate and thickness of the PTL are the critical parameters for mitigating mass transport limitation at high current densities. In fact, it was found that, for the size of the cells studied (25 cm² active area each), when both cells are operating at the same temperature of 60 °C, the low cost cell design will have a comparable performance to the conventional designed cell even at 5 A/cm² current density when; the operating pressure is ≥ 5 bar, the feed water flowrate is ≥ 0.024l/min∙cm², PTL porosity is 50 \%, PTL pore size is ≥ 11 µm and PTL thickness is 0.5 mm. At these operating, design and micro-structural conditions, the predicted difference between the polarizations of both cells will be only ~10 mV at 5 A/cm² operating current density.}, language = {en} } @misc{AbangWeissKrautz, author = {Abang, Roger Atini and Weiß, Sabine and Krautz, Hans Joachim}, title = {Impact of increased power plant cycling on the oxidation and corrosion of coal-fired superheater materials}, series = {Fuel}, volume = {2018}, journal = {Fuel}, number = {220}, issn = {0016-2361}, doi = {10.1016/j.fuel.2018.02.047}, pages = {521 -- 534}, abstract = {As power generation from variable renewable energy sources such as wind and solar power continues to increase in the future, fewer baseload power plants will be needed. As a result, high operational flexibility is becoming a vital requirement for conventional power plants to allow for the smooth integration of the variable renewable energy sources (v-RES) into the grid. To understand the impact of high operational flexibility (increased cycling) for coal-fired power plant materials, five commercial coal boiler superheater and reheater materials were investigated under isothermal and cyclic conditions for 1000 h each. The candidate alloys investigated were: T91, VM12-SHC, TP347-HFG, DMV304 HCu and DMV310 N. The results (weight change kinetics and metallographic analysis) after exposure at a metal surface temperature of 650 °C clearly showed the impact of increased flexibility on the corrosion and oxidation of the materials. Oxide growth (weight gain), metal loss, oxide spallation, and grain boundary attack were found to be more severe under cyclic conditions than under isothermal conditions.}, language = {en} } @misc{DahashMieckOchsetal., author = {Dahash, Abdulrahman and Mieck, Sebastian and Ochs, Fabian and Krautz, Hans Joachim}, title = {A comparative study of two simulation tools for the technical feasibility in terms of modeling district heating systems: An optimization case study}, series = {Simulation Modelling Practice and Theory}, volume = {91}, journal = {Simulation Modelling Practice and Theory}, issn = {1569-190X}, doi = {10.1016/j.simpat.2018.11.008}, pages = {48 -- 68}, abstract = {District heating dynamic models arise as an alternative approach to in-situ experimental investigations. The main advantage of dynamic modeling and simulation is the possibility to avoid technical and operational risks that might occur during in-situ experimental investigations (e.g. heat demand is not met, damages in the energy systems etc.). Within this study, the authors present two models for an existing district heating system in Cottbus, Germany. One model is developed using the tool EBSILON Professional, while the other one is developed using the Simscape toolbox for physical modeling in Matlab/Simulink. The models were experimentally validated against measured data from the considered district heating system. The results show that the Simscape model has a better fit and better response than the EBSILON model. Yet, some discrepancies were found between the measured and the simulated data and, therefore, the uncertainties of the models were addressed. A comparative study between both tools is presented. The EBSILON models permit only unidirectional flow, whereas the Simscape toolbox permits reverse flow. Nevertheless, the EBSILON model outperforms the Simscape model in computation time. In addition, this study presents an approach for dynamic thermo-hydraulic modeling of district heating networks. This approach is utilized to examine the role of district heating networks as heat storage as an optimization configuration. The numerical results show less start-ups for additional heat sources. Yet, higher heat losses from the network are observed due to the installation of unburied pipelines.}, language = {en} } @misc{SchierackRistauLisk, author = {Schierack, Kristin and Ristau, Herbert and Lisk, Alexander}, title = {Laudatio: Universit{\"a}ts-Professor Hans Joachim Krautz zum 65. Geburtstag}, series = {VGB PowerTech}, volume = {98}, journal = {VGB PowerTech}, number = {8}, issn = {1435-3199}, pages = {47 -- 48}, language = {de} } @misc{TannertZiemsVoigtetal., author = {Tannert, Daniel and Ziems, Christian and Voigt, Andr{\´e} and Fischer, Ulrich and Krautz, Hans Joachim}, title = {Wasserstoff- und Elektrolyseforschung an der BTU Cottbus - Senftenberg}, series = {VGB PowerTech}, volume = {98}, journal = {VGB PowerTech}, number = {8}, issn = {1435-3199}, pages = {65 -- 69}, language = {de} } @misc{ZiemsFischerKrautz, author = {Ziems, Christian and Fischer, Ulrich and Krautz, Hans Joachim}, title = {Entwicklung und anwendungsbezogene Charakterisierung von effizienten, hochleistungsf{\"a}higen 3D-Elektrodenmaterialien f{\"u}r die alkalische Druckelektrolysetechnologie}, series = {VGB PowerTech}, volume = {98}, journal = {VGB PowerTech}, number = {8}, issn = {1435-3199}, pages = {70 -- 74}, language = {de} } @misc{SakkasZiemsPosseltetal., author = {Sakkas, Nikolaos Panagiotis and Ziems, Christian and Posselt, Joachim and Krautz, Hans Joachim}, title = {Entwicklung von Algorithmen zur Einsatzplanung und Steuerung von Power-to-Heat-Anlagensystemen zur effizienteren Nutzung regenerativer {\"U}berschussenergie}, series = {VGB PowerTech}, volume = {98}, journal = {VGB PowerTech}, number = {8}, issn = {1435-3199}, pages = {82 -- 87}, language = {de} } @phdthesis{Wiedemann, author = {Wiedemann, Philipp}, title = {Modellierung und numerische Simulation der konvektiven Trocknung von Braunkohlepartikeln in einer blasenbildenden Wirbelschicht}, address = {Cottbus}, pages = {238}, abstract = {In der vorliegenden Arbeit werden die Modellierung und die numerische Simulation vonStr{\"o}mung, W{\"a}rme- und Stofftransport zur Abbildung eines Trocknungsprozesses vonBraunkohlepartikeln in einer blasenbildenden Wirbelschicht behandelt. Hierbei wird dasEuler-Euler Two Fluid Model zugrunde gelegt und die Beschreibung des Fließverhaltensder Feststoffphase mittels der Kinetic Theory of Granular Flow realisiert. Ausgehend voneinem {\"U}berblick zum aktuellen Stand der Forschung wird der Bedarf nach einer geeigne-ten Konfiguration von Modellparametern und Submodellen hinsichtlich der Str{\"o}mungs-modellierung sowie nach der Implementierung eines Trocknungsmodells abgeleitet und alsZielsetzung formuliert.Experimentelle Voruntersuchungen an einer Wirbelschichtanlage im Labormaßstab schaf-fen die Datenbasis f{\"u}r die sp{\"a}tere Validierung des Modells. Dabei erfolgt zun{\"a}chst eineBetrachtung einzelner Zustandspunkte von diskontinuierlichen Trocknungsprozessen, umdie darin auftretenden, str{\"o}mungstechnischen Ver{\"a}nderungen zu quantifizieren. Zur Be-wertung werden die makroskopischen Eigenschaften sowie Charakteristiken meso- undmikroskaliger Str{\"o}mungstrukturen herangezogen, die sich aus der Analyse von Druckfluk-tuationen ergeben. Des Weiteren werden die Trocknungsverl{\"a}ufe mehrerer Chargen f{\"u}rverschiedene Betriebsparameter aufgezeichnet.In einem ersten Untersuchungsschwerpunkt werden ausschließlich str{\"o}mungsmechanischeAspekte fokussiert. Auf Basis umfangreicher Sensitivit{\"a}tsanalysen zu den Einfl{\"u}ssen derrheologisch relevanten Parameter, der Impulsaustauschfunktion einschließlich der Parti-kelsph{\"a}rizit{\"a}t und der Randbedingungen f{\"u}r Beh{\"a}lterwand und Gaseinlass, sowie durchVergleiche mit den experimentellen Daten wird eine Parameterkonfiguration des Str{\"o}-mungsmodells vorgeschlagen. Die damit erzielten Ergebnisse sind insgesamt zufriedenstel-lend und geben die beobachteten Ver{\"a}nderungen im Trocknungsprozess korrekt wieder.Ursachen f{\"u}r bestehende Abweichungen zum Experiment werden diskutiert.Im zweiten Untersuchungsschwerpunkt wird der gesamte Trocknungsprozess betrachtet.Hierzu werden W{\"a}rme- und Stofftransportmechanismen innerhalb des Modells ber{\"u}cksich-tigt, wobei die eigens implementierte Trocknungskinetik auf Ebene der Partikel ansetzt.Die Einfl{\"u}sse der Sph{\"a}rizit{\"a}t und zwei verschiedener Formulierungen zur Berechnung derW{\"a}rme- und Stoff{\"u}bergangskoeffizienten werden untersucht. F{\"u}r den favorisierten Para-metersatz werden die Simulationen mit einem expliziten Vorw{\"a}rtsverfahren gekoppelt,wodurch die Trocknungsverl{\"a}ufe auf makroskopischer Zeitskale approximiert und somitmit den experimentellen Daten verglichen werden k{\"o}nnen. Es wird gezeigt, dass das vor-geschlagene Gesamtmodell die Trocknungsverl{\"a}ufe bei niedrigen bis m{\"a}ßigen Leerrohrge-schwindigkeiten zuverl{\"a}ssig abbilden kann. Auftretende Diskrepanzen werden diskutiertund weiterer Entwicklungsbedarf abgeleitet.V}, language = {de} } @phdthesis{Posselt, author = {Posselt, Joachim}, title = {Entwicklung eines Berechnungsmodells zur thermisch-geometrischen Dimensionierung eines Druck-Wirbelschicht-Verdampfungstrockners mit Tauchheizfl{\"a}chen am Beispiel polydisperser Braunkohle}, address = {Cottbus}, pages = {265}, abstract = {Im Rahmen dieser Arbeit wurde ein Berechnungsmodell zur thermisch-geometrischen Dimensionierung eines kontinuierlich arbeitenden Druck-Wirbelschicht-Verdampfungs-Trockners mit Tauchheizfl{\"a}chen f{\"u}r polydisperse Braunkohle erstellt. Zun{\"a}chst wurde auf Basis experimenteller Ergebnisse eine strukturell optimierte Grundgleichung zur Beschreibung des zeitlichen Feuchteverlaufes entwickelt. Dabei wurden die Besonderheiten des Trocknungsgutes (z.B. die Polydispersit{\"a}t und die Ausbildung einer Gleichgewichtsfeuchte) ber{\"u}cksichtigt. Mit Hilfe der f{\"u}r den Trockner aufgestellten Energiebilanzen wurde ein Modell zur Beschreibung des zeitlichen Verdampfungstrocknungsverlaufes entwickelt. Dabei wurde auch der Einfluss des Druckes in den Subgleichungen und Stoffwertberechnungen ber{\"u}cksichtigt. (Der {\"U}berdruck ist einer der Hauptunterschiede der DDWT zu zahlreichen anderen Trocknungsverfahren). Weiterf{\"u}hrend wurde unter Anwendung der Gleichungen zur Beschreibung der wirbelschicht-bedingten asymmetrischen Verweilzeitverteilung ein Gesamtmodell - das Trockner-Auslegungs-Modell (TRAM) - entwickelt und die Modellarchitektur detailliert beschrieben.}, language = {de} } @misc{AhmelsVossGagoetal., author = {Ahmels, Peter and Voß, Ulrike and Gago, Aldo and Lettenmeier, Philipp and Voglst{\"a}tter, Christopher and Schmitz, Steffen and Kleinickel, Cindy and Barsch, Markus and Rockmann, Rico and Pumpa, Martin and Fischer, Ulrich and Voigt, Andr{\´e}}, title = {Wasserstoff zur Windenergiespeicherung - Ergebnisse des Projektes WESpe}, series = {HZwei: das Magazin f{\"u}r Wasserstoff und Brennstoffzellen}, volume = {18}, journal = {HZwei: das Magazin f{\"u}r Wasserstoff und Brennstoffzellen}, number = {2}, issn = {1862-393X}, pages = {28 -- 30}, language = {de} } @misc{VoigtFischerTannertetal., author = {Voigt, Andr{\´e} and Fischer, Ulrich and Tannert, Daniel and Krautz, Hans Joachim}, title = {Analyse erneuerbarer P2H2 Energiesystemkonfigurationen unter Verwendung von Matlab}, series = {Nutzung regenerativer Energiequellen und Wasserstofftechnik 2017 ; 24. Symposium Nutzung Regenerativer Energiequellen und Wasserstofftechnik, Stralsund, 09. bis 11. November 2017}, journal = {Nutzung regenerativer Energiequellen und Wasserstofftechnik 2017 ; 24. Symposium Nutzung Regenerativer Energiequellen und Wasserstofftechnik, Stralsund, 09. bis 11. November 2017}, publisher = {HOST - Hochschule Stralsund}, address = {Stralsund}, isbn = {978-3-9817740-3-0}, pages = {143 -- 147}, language = {de} } @misc{FischerVoigtTannertetal., author = {Fischer, Ulrich and Voigt, Andr{\´e} and Tannert, Daniel and Krautz, Hans Joachim}, title = {Standortevaluierung und System-pfadanalyse im Forschungsprojekt WESpe - Wissenschaftliche Forschung zu Windwasserstoff-Energiespeichern}, series = {Nutzung regenerativer Energiequellen und Wasserstofftechnik 2016 ; energie-symposium, 23. Symposium Nutzung Regenerativer Energiequellen und Wasserstofftechnik, Stralsund, 3. - 5. November 2016}, volume = {2016}, journal = {Nutzung regenerativer Energiequellen und Wasserstofftechnik 2016 ; energie-symposium, 23. Symposium Nutzung Regenerativer Energiequellen und Wasserstofftechnik, Stralsund, 3. - 5. November 2016}, publisher = {Fachhochschule Stralsund}, address = {Stralsund}, isbn = {978-3-9817740-1-6}, pages = {143 -- 147}, language = {de} } @misc{KatzerKrautz, author = {Katzer, Christian and Krautz, Hans Joachim}, title = {Untersuchungen zur messtechnischen Erfassung von instation{\"a}ren Effekten eines Gas-/Kohle-Kombibrenners}, series = {29. Deutscher Flammentag : 17. - 18. September 2019 Ruhr-Universit{\"a}t Bochum}, journal = {29. Deutscher Flammentag : 17. - 18. September 2019 Ruhr-Universit{\"a}t Bochum}, abstract = {In diesem Beitrag wird ein Flammenbewertungsverfahren auf Basis eines Flammenw{\"a}chtersignals vorgestellt. Mit zunehmender Flexibilisierung der Verbrennungsanlagen und der Absenkung von Emissionsgrenzwerten wird eine unmittelbare Flammenanalyse f{\"u}r die Regelung der Brennersysteme zunehmend erforderlich. Auf Basis eines Flammenw{\"a}chtersignals wird mittels Frequenzanalyse ein erg{\"a}nzendes Auswertungsverfahren dargestellt. Anhand der vorgestellten Untersuchungen an einem Erdgas-/Kohle-Kombibrenner wird die Qualifizierung der Prozessmesstechnik f{\"u}r die Flammenbewertung und Brennersteuerung {\"u}berpr{\"u}ft. Die Ergebnisse im Erdgas- und Kohlebetrieb belegen, dass mit der erweiterten Signalanalyse eine Ver{\"a}nderung des Flammenverhaltens mit dem Flammenw{\"a}chtersignal in Zusammenhang gebracht werden kann. Dabei konnte einmal das Emissionsverhalten bei verschiedenen Brennereinstellungen beurteilt werden und andererseits ein Zugriff auf das Stabilit{\"a}tsverhalten der Kohleflamme erm{\"o}glicht werden. Durch die Analyse des Strahlungssignals der Chemilumineszenz des OH* bzw. CH*-Radikals ist ein Bezug zur Ver{\"a}nderung in der Reaktionszone hergestellt. Die entwickelte Bewertungsmethodik kann f{\"u}r die Entwicklung und Etablierung von Beobachter- und Regelmodellen von Brennersystemen genutzt werden.}, language = {de} } @misc{KatzerSchierackKrautz, author = {Katzer, Christian and Schierack, Frank and Krautz, Hans Joachim}, title = {Die TBK- Feuerung im Labor und an einem Großdampfer-zeuger: Parallelen im Last- und Emissionsverhalten}, series = {Verbrennung und Feuerung, 28. Deutscher Flammentag, Darmstadt, 06. und 07. September 2017}, journal = {Verbrennung und Feuerung, 28. Deutscher Flammentag, Darmstadt, 06. und 07. September 2017}, publisher = {D{\"u}sseldorf}, address = {VDI-Verl.}, isbn = {978-3-18-092302-4}, pages = {39 -- 51}, abstract = {Mit der steigenden Erzeugung volatilen Stroms aus erneuerbaren Energien werden die Anforderungen an die Flexibilit{\"a}t der konventionellen Kraftwerke erh{\"o}ht. Der Einsatz von St{\"u}tzfeuerungssystemen auf Basis von Trockenbraunkohle (TBK) erm{\"o}glicht die Erweiterung des Lastbereiches und der Lastgradienten am Dampferzeuger. Untersuchungen zum Teillastverhalten von TBK-Brennern wurden an der BTU Cottbus - Senftenberg an einem 400 kWth Verbrennungsversuchstand und an dem industriellen 30 MWth TBK-Staubbrenner der Firma BBS (Babcock Borsig Steinm{\"u}ller GmbH) durchgef{\"u}hrt. Der verf{\"u}gbare Einsatzbereich des Brenners ist maßgeblich von der Intensit{\"a}t den brennernahen Mischungsvorgang abh{\"a}ngig. Mit der Absenkung der Brennerleistung ist beispielsweise eine signifikante Steigerung der NOx-Emission verbunden. Dieser Effekt ist auf die Ver{\"a}nderung des brennernahen Str{\"o}mungsprofiles zur{\"u}ckzuf{\"u}hren. Mit Maßnahmen wie der Erh{\"o}hung der Drallzahl, Verteilung der Luftimpulsstr{\"o}me und Ver{\"a}nderung des Prim{\"a}rimpulses konnte eine Stabilisierung und Intensivierung der Reaktionszone und somit eine Verbesserte des Teillastverhaltens nachgewiesen werden. 1.}, language = {de} } @misc{KatzerSchierackTappeetal., author = {Katzer, Christian and Schierack, Frank and Tappe, Stephanie and Krautz, Hans Joachim}, title = {Ergebnisse der Untersuchungen zur Betriebsstabilit{\"a}t und des Emissionsverhaltens der TBK-Feuerung im Labor und an einem Großdampferzeuger}, series = {Kraftwerkstechnik 2017 : Strategien, Anlagentechnik und Betrieb}, journal = {Kraftwerkstechnik 2017 : Strategien, Anlagentechnik und Betrieb}, editor = {Beckmann, Michael}, publisher = {Saxonia Standortentwicklungs und -verwaltungsgesellschaft mbH}, address = {Freiberg}, isbn = {978-3-934409-79-8}, pages = {269 -- 278}, language = {de} } @book{Swat, author = {Swat, Steffen}, title = {Einf{\"u}hrung in die Simulation von Kraftwerken mit EBSILON®Professional Version 15}, edition = {1. Auflage}, publisher = {Neopubli GmbH}, address = {Berlin}, isbn = {978-3-754142-04-2}, pages = {81}, abstract = {EBSILON®Professional ist ein leistungsf{\"a}higes Modellierungssystem, welches zur Simulation von thermodynamischen Kreisprozessen entwickelt wurde. Es eignet sich als Hilfsmittel bei der Anlagenplanung, -auslegung und -optimierung von thermischen Kraftwerken mit einem Wasserdampf-Prozess oder einem Gasturbinen-Prozess sowie Anlagen mit erneuerbaren Energien (Biomasse, Windenergie, Solarenergie und Geothermie). Die Einf{\"u}hrung beschreibt die Grundprinzipien und die Arbeitsschritte zur Erstellung eines Modells der Anlage. Weiterhin wird die Arbeit mit der internen Programmierungsumgebung EbsScript und der Umgang mit der Berechnung von Zeitreihen vorgestellt.}, language = {de} } @book{Swat, author = {Swat, Steffen}, title = {Introduction to the simulation of power plants for EBSILON®Professional Version 15}, edition = {1. Auflage}, publisher = {Neopubli GmbH}, address = {Berlin}, isbn = {978-3-754142-08-0}, pages = {78}, abstract = {EBSILON®Professional is a powerful modelling system developed for the simulation of thermodynamic cycles. It is suitable as a tool for plant planning, design and optimization of thermal power plants with a steam process or a gas turbine process as well as plants with renewable energies (biomass, wind energy, solar energy and geothermal energy). The introduction describes the basic principles and the working steps to create a model of the plant. Furthermore, the work with the internal programming environment EbsScript and the handling of the calculation of time series is presented.}, language = {en} } @misc{ThummarAbangMenzeletal., author = {Thummar, Krunalkumar and Abang, Roger Atini and Menzel, Katharina and Groot, Matheus Theodorus de}, title = {Coupling a Chlor-Alkali Membrane Electrolyzer Cell to a Wind Energy Source: Dynamic Modeling and Simulations}, series = {Energies}, volume = {15}, journal = {Energies}, number = {2}, issn = {1996-1073}, doi = {10.3390/en15020606}, pages = {1 -- 26}, abstract = {Renewable energy sources are becoming a greater component of the electrical mix, while being significantly more volatile than conventional energy sources. As a result, net stability and availability pose significant challenges. Energy-intensive processes, such as chlor-alkali electrolysis, can potentially adjust their consumption to the available power, which is known as demand side management or demand response. In this study, a dynamic model of a chlor-alkali membrane cell is developed to assess the flexible potential of the membrane cell. Several improvements to previously published models were made, making the model more representative of state-of-the-art CA plants. By coupling the model with a wind power profile, the current and potential level over the course of a day was simulated. The simulation results show that the required ramp rates are within the regular operating possibilities of the plant for most of the time and that the electrolyte concentrations in the cell can be kept at the right level by varying inlet flows and concentrations. This means that a CA plant can indeed be flexibly operated in the future energy system.}, language = {en} } @misc{SakkasAbang, author = {Sakkas, Nikolaos Panagiotis and Abang, Roger Atini}, title = {Thermal load prediction of communal district heating systems by applying data-driven machine learning methods}, series = {Energy Reports}, volume = {8}, journal = {Energy Reports}, issn = {2352-4847}, doi = {10.1016/j.egyr.2021.12.082}, pages = {1883 -- 1895}, abstract = {Load forecasting is an essential part of the operational management of combined heat and electrical power units, since a reliable hour- and day-ahead estimation of their thermal and electrical load can significantly improve their technical and economic performance, as well as their reliability. Among different types of prediction techniques, data-driven machine learning methods appear to be more suitable for load estimation in operational systems, compared to the classical forward approach. Research so far has been concentrated mainly on the magnitude of buildings with single load types. It has only been extended to a limited degree on the level of a district heating network where several end users with different characteristics merge into one bigger scale heat consumer (city or group of communities). In this study, artificial neural networks are utilized, to develop a load prediction model for district heating networks. A segmented analytical multi-phase approach is employed, to gradually optimize the predictor by varying the characteristics of the input variables and the structure of the neural network. The comparison against the load prediction time series generated by a local communal energy supplier using a commercial software reveals that, although the latter is enhanced by manual human corrections, the optimized fully automatic predictors developed in the present study generate a more reliable load forecast.}, language = {en} } @misc{AkayBashkatovCoyetal., author = {Akay, {\"O}mer and Bashkatov, Aleksandr and Coy, Emerson and Eckert, Kerstin and Einarsrud, Kristian Etienne and Friedrich, Andreas and Kimmel, Benjamin and Loos, Stefan and Mutschke, Gerd and R{\"o}ntzsch, Lars and Symes, Mark D. and Yang, Xuegeng and Brinkert, Katharina}, title = {Electrolysis in reduced gravitational environments: current research perspectives and future applications}, series = {npj Microgravity}, volume = {8}, journal = {npj Microgravity}, issn = {2373-8065}, doi = {10.1038/s41526-022-00239-y}, abstract = {Electrochemical energy conversion technologies play a crucial role in space missions, for example, in the Environmental Control and Life Support System (ECLSS) on the International Space Station (ISS). They are also vitally important for future long-term space travel for oxygen, fuel and chemical production, where a re-supply of resources from Earth is not possible. Here, we provide an overview of currently existing electrolytic energy conversion technologies for space applications such as proton exchange membrane (PEM) and alkaline electrolyzer systems. We discuss the governing interfacial processes in these devices influenced by reduced gravitation and provide an outlook on future applications of electrolysis systems in, e.g., in-situ resource utilization (ISRU) technologies. A perspective of computational modelling to predict the impact of the reduced gravitational environment on governing electrochemical processes is also discussed and experimental suggestions to better understand efficiency-impacting processes such as gas bubble formation and detachment in reduced gravitational environments are outlined.}, language = {en} } @techreport{KrautzMoehlenkampSakkasetal., author = {Krautz, Hans Joachim and M{\"o}hlenkamp, Georg and Sakkas, Nikolaos Panagiotis and Gillung, Frank and Lenivova, Veronika}, title = {Verbundvorhaben AEL3D - Neuartige por{\"o}se 3D-Elektrodenmaterialen zur effizienteren alkalischen Wasserelektrolyse; Teilprojekt: Zellbau und Systemtests : fachlicher Abschlussbericht : Projektlaufzeit: 01.09.2016-31.12.2021}, publisher = {KWT Lehrstuhl Kraftwerkstechnik, BTU Brandenburgische Technische Universit{\"a}t Cottbus-Senftenberg}, address = {Cottbus}, doi = {10.2314/KXP:1859085385}, pages = {147}, language = {de} } @techreport{KrautzMoehlenkampKatzeretal., author = {Krautz, Hans Joachim and M{\"o}hlenkamp, Georg and Katzer, Christian and Klatt, Matthias}, title = {Konzepte und Betriebsstrategien f{\"u}r lastflexible Feuerungs- und Dampfsysteme : Abschlussbericht : Laufzeit des Vorhabens: 01.09.2016 bis 31.12.2021}, publisher = {btu Brandenburgische Technische Universit{\"a}t Cottbus-Senftenberg}, address = {Cottbus}, doi = {10.2314/KXP:1861122357}, pages = {223}, language = {de} } @article{ReimannKohlenbachRoentzschetal., author = {Reimann, Ansgar and Kohlenbach, Paul and R{\"o}ntzsch, Lars and Schneider, Clemens}, title = {Development and validation of a quasi-2D electrolysis stack model with a focus on dynamic thermal behavior}, series = {International Journal of Hydrogen Energy}, volume = {118}, journal = {International Journal of Hydrogen Energy}, publisher = {Elsevier BV}, issn = {0360-3199}, doi = {10.1016/j.ijhydene.2025.03.225}, pages = {457 -- 471}, abstract = {- Novel dynamic PEM stack model with focus on thermal behavior is presented. - Model incorporates gas-liquid heat transfer and pressure drop phenomena. - Electrochemical and dynamic thermal behavior is validated with experimental data. - Validation shows higher gas fraction in cooling water increases heat transfer. Maintaining a constant stack temperature and minimizing temperature gradients within the stack during operation is critical to the efficiency and durability of proton exchange membrane (PEM) electrolyzers. At the same time, the significant amount of heat released during operation provides opportunities to reuse this heat, potentially improving economic efficiency and contributing to the decarbonization of the heating sector. The design of stack temperature and heat recovery control systems requires accurate and effective models that describe the dynamic thermal behavior of the stack during load changes without being overly computationally intensive. Therefore, this paper presents a dynamic quasi-2D model of a PEM electrolysis stack that rapidly calculates these dynamic processes in a generally applicable manner. The model also incorporates phenomena such as gas and liquid crossover and pressure drop. We validated the performance of the model with experimental data from a PEM electrolysis test bench and demonstrated its accuracy in describing the electrochemical and dynamic thermal behavior. The stack voltage was simulated with a mean absolute deviation (MAD) of 0.0895 V and the anode outlet temperature with an MAD of 0.127 K, while the simulated time constants of the thermal step responses showed an MAD of 4.06 \%.}, language = {en} } @incollection{SampangiRoentzsch, author = {Sampangi, Shiva Kumar and R{\"o}ntzsch, Lars}, title = {Electrolysis - Proton-exchange membrane electrolyzer | Proton exchange membrane water electrolysis: State-of-the-art technique and systems}, series = {Reference Module in Chemistry, Molecular Sciences and Chemical Engineering}, booktitle = {Reference Module in Chemistry, Molecular Sciences and Chemical Engineering}, editor = {Reedijk, Jan}, publisher = {Elsevier}, isbn = {978-0-12-409547-2}, doi = {10.1016/B978-0-323-96022-9.00237-1}, language = {en} } @misc{ReimannKohlenbachRoentzsch, author = {Reimann, Ansgar and Kohlenbach, Paul and R{\"o}ntzsch, Lars}, title = {Development of a novel quasi-2D PEM Electrolyzer Model in Modelica}, series = {Proceedings of the 15th International Modelica Conference 2023, Aachen, October 9-11}, journal = {Proceedings of the 15th International Modelica Conference 2023, Aachen, October 9-11}, publisher = {Link{\"o}ping University Electronic Press}, issn = {1650-3686}, doi = {10.3384/ecp20463}, pages = {9}, abstract = {To increase the efficiency of PEM electrolysis, simulation models are required that accurately describe the system's electrochemical and thermal behavior in a computationally efficient manner and are thus suitable for developing control strategies. Therefore, a pseudo-2D PEM electrolyzer model is presented in this paper, which is a compromise between the previously developed models regarding their model complexity. The electrochemical behavior is described with equations commonly used in the literature and the thermal behavior with correlations for gas-liquid heat transfer. Preliminary validation indicates that the model can describe the electrochemical behavior and thermal dynamics of a PEM electrolysis stack with good accuracy.}, language = {en} } @misc{DanilaKunzRoentzsch, author = {Danila, Kevin and Kunz, Philip and R{\"o}ntzsch, Lars}, title = {Dynamic operation of low-temperature electrolyzer systems in modular large-scale chemical plants}, series = {Chemie - Ingenieur - Technik : CIT}, volume = {2025}, journal = {Chemie - Ingenieur - Technik : CIT}, publisher = {Wiley-VCH GmbH}, issn = {0009-286X}, doi = {10.1002/cite.202400140}, pages = {1 -- 11}, abstract = {As one of the main contributors to the greenhouse gas emissions worldwide, the reduction of emissions in chemical industry is indispensable. The production of hydrogen from renewable energy sources using water electrolysis can contribute to this goal. However, the dynamic character of renewable energy sources leads to major challenges regarding the dynamic operation of the production process. Here, a model of a modular low-temperature electrolyzer plant is presented. The effect of available time resolution of the source electricity as well as the impact of the integration time step is studied. With the presented model the positive effect of load-dependent operation of modular electrolyzer plants with fluctuating availability of source electricity on the total hydrogen output is demonstrated.}, language = {en} } @misc{SharmaRoentzschShahi, author = {Sharma, Prerana and R{\"o}ntzsch, Lars and Shahi, Vinod K.}, title = {Advancements towards optimization of metal-organic framework-based polymer electrolyte membranes for aqueous redox flow batteries}, series = {Journal of materials chemistry : A, materials for energy and sustainability}, volume = {13}, journal = {Journal of materials chemistry : A, materials for energy and sustainability}, number = {17}, publisher = {Royal Society of Chemistry (RSC)}, address = {London}, issn = {2050-7488}, doi = {10.1039/D4TA08720H}, pages = {11952 -- 11988}, abstract = {Aqueous redox flow batteries (ARFBs) are considered a potential technology for large-scale energy storage owing to their eco-friendliness, high current density, and tuneable capacity. Polymer electrolyte membranes (PEMs) are vital components of ARFB, but they suffer from significant capacity/efficiency deterioration due to a lack of advancement in structural framing. To enhance the effectiveness of ARFBs, various membrane types have been optimized. However, the development of an efficient PEM remains a significant problem. Metal-organic frameworks (MOFs) made up of metal sites and organic linkers have gained significant scientific interest. As a result of their large surface area, adjustable pore diameters, and customized functionality, MOF-based PEMs are regarded as effective separators for ARFB. This review covers the state of the art MOF-based PEMs as ARFB separators. In recent years, significant efforts have been made to utilize the unique characteristics of MOFs as they not only improve the conductivity (attributed to their 3D channel structure) and gradient distribution in the polymer framework but also stabilize and mitigate active species cross-over by regulating the effective pore size. The aforementioned tactics can stimulate more research on energy storage technologies and provide future insight into the development and design of size-sieving separators for ARFB.}, language = {en} } @misc{JanaChauhanMuthukumaretal., author = {Jana, Sayantan and Chauhan, Nikhil and Muthukumar, Palanisamy and R{\"o}ntzsch, Lars}, title = {Transient analysis and performance prediction of a metal hydride based thermal energy storage system with Integrated cooling and heat upgradation}, series = {Heat transfer engineering : an international journal}, journal = {Heat transfer engineering : an international journal}, publisher = {Taylor \& Francis}, address = {London}, issn = {0145-7632}, doi = {10.1080/01457632.2025.2521599}, pages = {1 -- 13}, abstract = {This work embodies a numerical model development and simulation of a metal hydride-based thermal energy storage system with integrated cooling as well heat upgradation. The concept of this system is unique as it operates on thermal drive during the energy storage cycle while during the energy release cycle it is compressor-operated. The utility of the mechanical compressor in the system is two-fold i.e., one operation mode would harness cooling, and another operation mode would fetch heat upgradation. The numerical model devised is a lumped parameter model which solves for hydrogen concentration and temperature of the linked metal hydride reactors. The proposed thermal energy storage system is of 5 MJ capacity which engages tube bundle reactor settings for both high-temperature and low-temperature hydride alloys. Each energy storage and release cycles are simulated for a fixed duration of 10000 s. For a fixed heat supply and heat recovery temperatures of 623 K and 573 K, the system offered cooling coefficient of performance in the range of 1.43-1.58 at 283-293 K. Also, approximately 77\% of the energy stored at 623 K could be retrieved at 573 K. In heat upgradation operation mode, 10-30 K temperature lift was accomplished.}, language = {en} } @misc{SakkasGillungThummaretal., author = {Sakkas, Nikolaos P. and Gillung, Frank and Thummar, Krunalkumar and Abang, Roger and R{\"o}ntzsch, Lars}, title = {Advanced pressurized alkaline water electrolysis at high temperatures up to 130 °C}, series = {International journal of hydrogen energy}, volume = {149}, journal = {International journal of hydrogen energy}, publisher = {Elsevier BV}, address = {Amsterdam}, issn = {0360-3199}, doi = {10.1016/j.ijhydene.2025.150075}, pages = {1 -- 12}, abstract = {Operating alkaline water electrolysers above 100 °C improves electrolyte conductivity and reaction kinetics significantly. To examine alkaline water electrolysis in this area in more detail a high-temperature pressurized test rig is designed and constructed. Nickel (Ni) foam electrodes coated with Raney nickel (Raney Ni) or nickel manganese (NiMn) and expanded Ni mesh electrodes coated with nickel(II) oxide (NiO) are utilized and the effect of electrolyte flow rate, electrode structure, pressure and temperature variation on the cell performance at temperatures up to 130 °C and pressures up to 16 bar are investigated. At the maximum current density of 1.67 A/cm2, 110 °C and 16 bar the electrode combination of Raney Ni coated Ni foam as cathode and NiO coated expanded Ni mesh electrode as anode attain the best outcome with a cell voltage of 2.29 V. In a 70 h duration test three-dimensional (3D) Ni foam electrodes with Raney Ni cathode and NiMn anode catalyst show a moderate cell degradation of 9.26 μV/h.}, language = {en} } @misc{SampangiJarubulaElasmaretal., author = {Sampangi, Shiva Kumar and Jarubula, Charath Krishna and Elasmar, Mohamed and R{\"o}ntzsch, Lars}, title = {Advanced anion exchange membrane electrolyser with 360 cm² active cell area}, series = {EFCF 2025 : Fuel Cells, Electrolysers \& H2 Processing}, journal = {EFCF 2025 : Fuel Cells, Electrolysers \& H2 Processing}, publisher = {European Fuel Cell Forum AG}, address = {Luzern}, doi = {10.5281/zenodo.17244119}, pages = {1 -- 6}, abstract = {Anion Exchange Membrane Water Electrolysis (AEMWE) has emerged as a promising technology for generating green hydrogen, particularly using intermittent renewable energy sources. AEMWE offers a compelling opportunity for cost-effective and sustainable hydrogen production by combining the advantages of traditional alkaline water electrolysis, such as the use of abundant and low-cost catalysts, with the benefits of Proton Exchange Membrane (PEM) electrolysis, which includes membrane separation with pure or low-concentration alkaline water and operation at high current densities. However, the widespread commercialization of AEMWE remains in its early stages, with small-scale active cell areas (less than 300 cm²) and ongoing challenges related to performance and durability. Consequently, it is vital to develop high-performance, durable AEMWE cells with larger active areas to facilitate the broader adoption of this technology. This contribution presents our recent progress in AEMWE, focusing on the development of cells with an active area of up to 360 cm². In particular, we are advancing AEMWE technology to Technology Readiness Level (TRL) 5/6, incorporating precious metal-free catalysts and advanced membranes to enhance the flexibility and efficiency of hydrogen production. As part of this effort, we have designed and experimentally tested a 100 cm² AEMWE cell and conceptualized and designed a 4-kW short-stack with a total active cell area of 1800 cm², as shown in Figure. 1, for high-pressure operation at 30 bar. Our ongoing efforts includes the laboratory testing of this newly designed stack at high pressure operation and evaluating its electrochemical performance and durability up to 1,000 h continuous operation using precious metal-free electrocatalysts.}, language = {en} } @techreport{KlattPfeifferBendigetal., author = {Klatt, Matthias and Pfeiffer, Klaus and Bendig, Martin and Platta, Kristian and Matzekat, David}, title = {Betrachtungen zur Mindesterzeugung von Braunkohlekraftwerken im Kontext des Netzbetriebs}, publisher = {Brandenburgische Technische Universit{\"a}t, Fachgebiet Dezentrale Energiesysteme [u.a.]}, address = {Cottbus ; Senftenberg}, language = {de} } @misc{DanilaVollmerKunz, author = {Danila, Kevin and Vollmer, Jan and Kunz, Philip}, title = {Performance evaluation of reanalysis models for upsampling of solar irradiance and wind speed data}, series = {Renewable energy}, volume = {261}, journal = {Renewable energy}, publisher = {Elsevier BV}, address = {Amsterdam}, issn = {0960-1481}, doi = {10.1016/j.renene.2026.125301}, pages = {1 -- 13}, abstract = {The transition to renewable energy sources is a cornerstone of modern energy system transformation. Yet, the integration of solar and wind power remains challenging due to limited availability of high-resolution time series data. Accurate modeling and forecasting of renewable energy generation are essential for grid stability, and the effective deployment of technologies such as water electrolysis. However, most available datasets are provided at coarse temporal resolutions, which restricts their utility for dynamic system analysis and hinders the development of robust operational strategies. This study addresses this critical gap by evaluating the performance of reanalysis models and introducing a statistical upsampling approach that generates data with 1-min resolution from reanalysis data with 1-h resolution using a first-order Markov chain Monte Carlo method. The method is validated against measured data. The normalized root-mean-square error of the simulated data is less than 10\% and the mean intra-hour standard deviation differs from 4.8\% to 9.1\% compared to measured values for solar irradiance and wind speed. The generated data facilitates the optimization of system operation, and enhances the planning of sector-coupled infrastructures. Ultimately, this approach enables reliable integration of renewable energy despite limited data availability and thus contributes to the advancement of the sustainable energy transition.}, language = {en} } @misc{DanilaKunzRoentzsch, author = {Danila, Kevin and Kunz, Philip and R{\"o}ntzsch, Lars}, title = {Low-temperature electrolysis model optimized for improved performance in dynamic simulations}, series = {International journal of hydrogen energy}, volume = {223}, journal = {International journal of hydrogen energy}, publisher = {Elsevier BV}, address = {Amsterdam}, issn = {0360-3199}, doi = {10.1016/j.ijhydene.2026.154294}, pages = {1 -- 12}, abstract = {Traditional hydrogen production methods contribute significantly to greenhouse gas emissions, making technological change essential. Water electrolysis powered by renewable energy offers a promising route for sustainable hydrogen production. However, the variability of renewables challenges efficient electrolyzer operation, often requiring detailed simulations with long time series and high computational effort. We present a dynamic model of a low-temperature electrolyzer system optimized for computational efficiency. The model increases computational speed by a factor of 1000 compared to full-balance models while maintaining accuracy above 99\% in hydrogen prediction. The simplified model is used to investigate the benefits of modularization in large-scale hydrogen plants. Results show that modularization has a minor effect on overall output but significantly increases operational time. This extended production window can reduce the need for large-scale hydrogen storage, especially when integrated with a continuous hydrogen consumer.}, language = {en} } @misc{ReimannKohlenbachRoentzschetal., author = {Reimann, Ansgar and Kohlenbach, Paul and R{\"o}ntzsch, Lars and Schneider, Clemens}, title = {Neural network-based model predictive control for waste heat recovery from PEM electrolysis with heat pumps}, series = {Energy conversion and management}, volume = {356}, journal = {Energy conversion and management}, publisher = {Elsevier BV}, address = {Amsterdam}, issn = {0196-8904}, doi = {10.1016/j.enconman.2026.121305}, pages = {1 -- 20}, abstract = {Hydrogen is expected to play a key role in future energy systems, with PEM electrolysis being particularly suitable for producing hydrogen from renewable sources. However, a significant amount of heat is released during operation. Utilizing this heat in heating networks or industrial processes could improve economic efficiency and help decarbonize the heating sector. Since PEM electrolyzers operate at relatively low temperatures, many applications need heat pumps to increase the temperature of the waste heat. Such a coupled system requires a controller that can handle the thermal management of the electrolysis stack with the heat pump. However, the rapid load changes of a PEM electrolyzer coupled with fluctuating renewable energy sources pose a challenge to the controller, as it must stabilize both the electrolyzer's cooling cycle and the heat pump's refrigeration cycle simultaneously. Therefore, this paper presents a model predictive controller (MPC) based on neural networks that efficiently controls waste heat recovery while meeting the temperature requirements of the electrolyzer and the heat sink. We investigated the performance of the control strategy in numerical case studies and compared it with conventional control using proportional-integral (PI) controllers. We could demonstrate that our method provides significant improvements in terms of minimizing temperature fluctuations and maximizing heat recovery efficiency. Under the influence of volatile power input, the MPC could increase the average efficiency of the heat pump by up to 7 \%, reduce the use of auxiliary heating energy by up to 52 \%, and reduce the average and maximum deviation from the temperature setpoints by up to 1.4 K and 10.4 K, respectively, compared to PI control.}, language = {en} }