@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} } @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} } @inproceedings{PosseltKrautz, author = {Posselt, Joachim and Krautz, Hans Joachim}, title = {Untersuchung des Einflusses der Korngr{\"o}ße auf die Trocknungskinetik von Braunkohle}, series = {45. Kraftwerkstechnisches Kolloquium, Dresden, Oktober 2013}, booktitle = {45. Kraftwerkstechnisches Kolloquium, Dresden, Oktober 2013}, publisher = {TK-Verlag}, address = {Neuruppin}, isbn = {978-3-944310-04-6}, 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} } @inproceedings{OwczarekKreulKrautz, author = {Owczarek, Christian and Kreul, Klaus-J{\"u}rgen and Krautz, Hans Joachim}, title = {Erste Untersuchungen des Str{\"o}mungsfeldes einer Zykloidbrennkammer. Konferenz Forschung f{\"u}r die Kraftwerkstechnik}, abstract = {Vortrag auf Konferenz Forschung f{\"u}r die Kraftwerkstechnik, D{\"u}sseldorf}, language = {de} } @inproceedings{OwczarekKrautzGriebeetal., author = {Owczarek, Christian and Krautz, Hans Joachim and Griebe, Steffen and Schrader, A. and Paulick, G.}, title = {Progressive combustion of lignite and sludge in atmospheric cycloid combustion system}, language = {en} } @inproceedings{OwczarekKrautzGriebe, author = {Owczarek, Christian and Krautz, Hans Joachim and Griebe, Steffen}, title = {Cycloidal combustion - a new concept for industrial combustion with low-calorific fuels}, language = {en} } @inproceedings{OwczarekKrautzGriebe, author = {Owczarek, Christian and Krautz, Hans Joachim and Griebe, Steffen}, title = {Entwicklung eines Feuerungssystems f{\"u}r die dezentrale W{\"a}rmeversorgung auf Basis von Braunkohle}, abstract = {Vortrag auf Tagung "Die neuen Kraftwerke der VEAG", BTU Cottbus}, language = {de} } @inproceedings{OwczarekFunke, author = {Owczarek, Christian and Funke, W.}, title = {Komponententestanlage f{\"u}r neue Kraftwerkstechniken}, language = {de} } @inproceedings{Owczarek, author = {Owczarek, Christian}, title = {Weiterentwicklung der Druckwirbelschichtfeuerung f{\"u}r Braunkohle}, language = {de} }