@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} } @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{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} } @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{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{Merzsch, author = {Merzsch, Matthias}, title = {Druckaufgeladene Dampfwirbelschicht-Trocknung von Braunkohle - Eine kleine Reise durch die Geschichte der Trocknung speziell die der Braunkohlen}, series = {VGB PowerTech}, volume = {98}, journal = {VGB PowerTech}, number = {8}, issn = {1435-3199}, pages = {49 -- 57}, abstract = {At first I was wondering what the structure of an article about pressurized steam fluidized bed drying could look like. After some thought, I knew that it should be divided into two parts. In order to highlight the creative and inventive spirit of former engineers, as well as their struggle to increase the efficiency of drying machines, a historical outline of the drying technology in general and the concept of steam fluidized bed drying in particular will form the first part of the article. The second part will present the practical and research contribution of Prof. Krautz and his colleagues to the advancement of this field. The article as a whole will be able to provide an overview of the coal/lignite drying, with focus on the pressurized steam fluidized bed drying principle implemented in the Lusatian mining area.}, language = {de} }