TY - JOUR A1 - Dubberke, Frithjof H. A1 - Linnemann, Matthias A1 - Abbas, Wameedh Khider A1 - Baumhögger, Elmar A1 - Priebe, Klaus-Peter A1 - Roedder, Maximilian A1 - Neef, Matthias A1 - Vrabec, Jadran T1 - Experimental setup of a cascaded two-stage organic Rankine cycle JF - Applied Thermal Engineering N2 - In combination with a bottoming cycle, operated with a pure fluid in transcritical mode, the usage of a zeotropic mixture as a working fluid appears to be exergetically favorable for power cycle efficiency in cascaded two-stage organic Rankine cycles (CORC). A CORC is set up and initially tested with cyclopentane and propane as working fluids in its high temperature and low temperature cycle, respectively. A thermal oil cycle serves as the heat source and is powered electrically with a maximum heat flow of 158 kW. The design of this experimental setup allows for a rapid replacement of individual components and for a wide range of conditions in terms of fluids and thermodynamic states. The components of all cycles and the measurement and control technology are described in detail. A testing procedure is presented, followed by a discussion of the measurement results, where it is shown that the intended concept of two cascaded organic Rankine cycles is operational and that the measured data are consistent. KW - organic Rankine cycle KW - cascade KW - multicomponent working fluid KW - temperature-glide KW - pinch point KW - exergetice efficiency Y1 - 2018 U6 - https://doi.org/10.1016/j.applthermaleng.2017.11.137 VL - 131 SP - 958 EP - 964 PB - Elsevier ER - TY - RPRT A1 - Adam, Mario A1 - Dreher, Martina A1 - Ebling, Dirk A1 - Knopp, Reinhold A1 - Neef, Matthias A1 - Niess, Robert A1 - Pohl, Tobias A1 - Stahl, Wilhelm A1 - van Rießen, Anne A1 - Waldow, Friederike A1 - Weber, Konradin A1 - Weis, Stephanie T1 - LUST Forschungsprojekt - lebenswerte und umweltgerechte Stadt N2 - LUST (lebenswerte und umweltgerechte Stadt) ist ein interdisziplinäres Projekt der Fachbereiche Architektur, Maschinenbau und Verfahrenstechnik sowie Kultur- und Sozialwissenschaften der Hochschule Düsseldorf. Mittelpunkt des Projektes ist die fachübergreifende Entwicklung neuer Konzepte für eine lebenswerte und umweltgerechte Stadt. Es wurde gefördert vom Land Nordrhein-Westfalen im Rahmen des Programms „FH Struktur“. N2 - LUST (Liveable and environment-friendly Urban SiTe) is an interdisciplinary project of the faculties of Architecture, Mechanical and Process Engineering as well as Social Studies and Cultural Sciences at the University of Applied Sciences Düsseldorf. The four-year (2013 – 2016) project is funded by the Ministry of Innovation, Science and Research of North Rhine–Westphalia. The aim is to develop holistic, new concepts for a liveable and environmentally friendly city in a multidisciplinary manner. KW - Stadtentwicklung KW - lebenswert KW - umweltgerecht KW - substainable urban development KW - environmentally friendly KW - liveable Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:due62-opus-11458 SN - 978-3-941334-43-4 CY - Düsseldorf ER - TY - JOUR A1 - Frank, Lena A1 - Rödder, Maximilian A1 - Neef, Matthias A1 - Adam, Mario T1 - Heating, Ventilation, Domestic Appliances – an Energy Integrated System Concept for the Household of the Future JF - Energy Y1 - 2021 U6 - https://doi.org/10.1016/j.energy.2021.121303 SN - 0360-5442 VL - 234 PB - Elsevier ER - TY - CHAP A1 - Dubberke, Frithjof A1 - Priebe, Klaus-Peter A1 - Vrabec, Jadran A1 - Neef, Matthias A1 - Rödder, Maximilian T1 - Thermodynamic simulation and experimental validation of a cascaded two-stage organic Rankine cycle T2 - ASME ORC 2015, Brussels KW - simulation Y1 - 2015 CY - Brussels ER - TY - CHAP A1 - Rödder, Maximilian A1 - Neef, Matthias A1 - Laux, Christoph A1 - Priebe, Klaus-P. T1 - Systematic Fluid Selection for Organic Rankine Cycles (ORC) and Performance Analysis for a Combined High and Low Temperature Cycle T2 - Volume 3: Coal, Biomass and Alternative Fuels; Cycle Innovations; Electric Power; Industrial and Cogeneration N2 - The organic Rankine cycle (ORC) is an established thermodynamic process that converts waste heat to electric energy. Due to the wide range of organic working fluids available the fluid selection adds an additional degree of freedom to the early design phase of an ORC process. Despite thermodynamic aspects such as the temperature level of the heat source, other technical, economic and safety aspects have to be considered. For the fluid selection process in this paper, 22 criteria were identified in six main categories while distinguishing between elimination and tolerance criteria. For an ORC design, the suggested method follows a practical engineering approach and can be used as a structured way to limit the number of interesting working fluids before starting a detailed performance analysis of the most promising candidates. For the first time the selection process is applied to a two-stage reference cycle which uses the waste heat of a large reciprocating engine for cogeneration power plants. It consists of a high temperature and a low temperature cycle in which the condensation heat of the high temperature (HT) cycle provides the heat input of the low temperature (LT) cycle. After the fluid selection process the detailed thermodynamic cycle design is carried out with a thermodynamic design tool that also includes a database for organic working fluids. The investigated ORC cycle shows a net thermal efficiency of about 17,4% in the high temperature cycle with Toluene as the working fluid and 6,2% in low temperature cycle with iso-Butane as the working fluid. The electric efficiency of the cogeneration plant increases from 40,4% to 46,97% with the both stages of the two-stage ORC in operation. Y1 - 2015 UR - https://asmedigitalcollection.asme.org/GT/proceedings/GT2015/56673/Montreal, Quebec, Canada/236733 SN - 978-0-7918-5667-3 U6 - https://doi.org/10.1115/GT2015-42432 PB - American Society of Mechanical Engineers ER - TY - CHAP A1 - Helm, Peter A1 - Spliethoff, Hartmut A1 - Neef, Matthias T1 - Closing the Gap: Measuring Bristle Blow Down of Brush Seals T2 - 19 th International Conference on Fluid Sealing, Poitiers Y1 - 2007 CY - Poitiers ER - TY - CHAP A1 - Neef, Matthias A1 - Hepermann, Florian A1 - Sürken, Norbert A1 - Schettel, Joachim T1 - Brush Seal Porosity Modeling: Applicability and Limitations T2 - ETC7 – 7th Conference on Turbomachinery, Athens Y1 - 2007 CY - Athens ER - TY - CHAP A1 - Neef, Matthias A1 - Hummel, Dietrich T1 - Euler solutions for a finite-span flapping wing T2 - "Fixed, flapping and rotary wing vehicles at very low Reynolds numbers, Notre Dame, Indiana, USA Y1 - 2000 ER - TY - JOUR A1 - Baier, André A1 - Neef, Matthias T1 - Studierende lehren und lernen sozial-ökologische Verantwortung JF - Die Neue Hochschule KW - Verantwortung Y1 - 2019 VL - 60 IS - 5 SP - 8 EP - 11 ER - TY - CHAP A1 - Neef, Matthias T1 - Innerstädtische Nutzung von Kleinwindkraftanlagen: Potentiale und Hürden T2 - Mülheimer Initiative für Klimaschutz, 06.05.2013 Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:due62-opus-21017 CY - Mülheim an der Ruhr ER - TY - THES A1 - Neef, Matthias T1 - Analyse des Schlagfluges durch numerische Strömungsberechnung N2 - Mit Hilfe eines Finite-Volumen-Verfahrens wird die dreidimensionale reibungsbehaftete Stroemung um einen schlagenden Fluegel berechnet. Die Bewegungsparamter sind dabei vergleichbar mit den Bedingungen im Reiseflug grosser Voegel. Das numerische Verfahren wird fuer den gezeigten Anwendungsfall, indem eine Methode zur Realisierung von beliebigen periodischen Bewegungen implemetiert wird. Eine Verifizierung erfolgt durch den Vergleich mit analytischen, numerischen und experimentellen Ergebnissen aus der Literatur. Mit dem verifizierten Verfahren werden die instationaeren Groessen wie Druck und Geschwindigkeiten in der Umgebung des bewegten Fluegels berechnet. Daraus ergeben sich ferner die zeitlich gemittelten Groessen wie Schub und Wirkungsgrad des Schlagfluges. Ausserdem wird die Interaktion von Laengs- und Querwirbeln im Nachlauf des schlagenden Fluegels untersucht. Es zeigt sich ein dominanter Einfluss der pulsierenden Randwirbel aufgrund der endlichen Spannweite, waehrend die Anfahr- und Stoppwirbel, verursacht durch die Fluegelbewegung, im Reiseflug grosser Voegel nahezu vernachlaessigbar erscheinen. N2 - The three-dimensional viscous flow around a flapping wing is calculated by means of a finite volume code. The invoked motion parameters are comparable with the conditions in cruising flight of large birds. For the described application the numerical procedure is extended by implementing a method for realisation of arbitrary periodic motions. The verification is obtained by comparison with analytical, numerical and experimental results from existing literature. With the verified method the instationary quantities such as pressure and velocity are known in the vicinity of the wing. This also yields the time averaged values such as thrust and propulsive efficiency of the flapping wing propulsion. Additionally, the interaction between longitudinal and transverse vortices in the wake of the flapping wing is investigated. A dominant influence of the oscillating tip vortices due to the finite span can be seen, while the starting and stopping vortices due to the wing motion appear almost negligible in the cruising flight of large birds. Y1 - 2002 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:084-14501 UR - http://www.digibib.tu-bs.de/?docid=00001361 VL - ZLR-Forschungsbericht, 2 ER - TY - CHAP A1 - Neef, Matthias A1 - Fussenecker, Claudia A1 - Niemann, Jörg A1 - Zielke, Thomas ED - Clark, Robin ED - Munkebo Hussmann, Peter ED - Järvinen, Hannu-Matti T1 - Publish your undergraduate research! A mandatory course for master students in engineering T2 - Creativity, innovation and entrepreneurship for engineering education excellence : proceedings of the 46th SEFI Annual Conference 2018, Copenhagen, Denmark N2 - Undergraduate students in engineering often have little exposure to the world of scientific publishing and the culture of sharing research work. While the beneficial exchange between research and teaching is well promoted, while the benefits of conference participation for students have already been surveyed and while courses on scientific writing are readily available, the concept of mini-conferences as part of the curriculum combines all three aspects into one. Therefore, the course "Engineering Conferences" was developed and installed as a mandatory part of a master program for engineering students. The idea is to go beyond simply teaching the standards of academic writing and skills for using scientific publications. By using a learner-centered approach, the students are engaged in typical activities around an active attendance of a real conference. Based on their bachelor thesis, they write a paper complying with common academic standards, submit the paper and review submissions of their fellow students. They also produce a poster and defend their work in a poster session held publicly on campus. This contribution is based on the experience from the first four terms teaching the course. It explains the didactic rationale behind the concept and individual teaching modules, it comprises the collection of useful resources for teaching and organizing scientific publishing and it includes the consequences drawn from course evaluation results. Y1 - 2018 SN - 978-2-87352-016-8 PB - SEFI - Société Européenne pour la Formation des Ingénieurs CY - Brussels ER - TY - JOUR A1 - Feseker, Daniel A1 - Kinell, Mats A1 - Neef, Matthias T1 - Experimental Study on Pressure Losses in Circular Orifices With Inlet Cross Flow JF - Journal of Turbomachinery N2 - The ability to understand and predict the pressure losses of orifices is important in order to improve the air flow within the secondary air system. This experimental study investigates the behavior of the discharge coefficient for circular orifices with inlet cross flow which is a common flow case in gas turbines. Examples of this are at the inlet of a film cooling hole or the feeding of air to a blade through an orifice in a rotor disk. Measurements were conducted for a total number of 38 orifices, covering a wide range of length-to-diameter ratios, including short and long orifices with varying inlet geometries. Up to five different chamfer-to-diameter and radius-to-diameter ratios were tested per orifice length. Furthermore, the static pressure ratio across the orifice was varied between 1.05 and 1.6 for all examined orifices. The results of this comprehensive investigation demonstrate the beneficial influence of rounded inlet geometries and the ability to decrease pressure losses, which is especially true for higher cross flow ratios where the reduction of the pressure loss in comparison to sharp-edged holes can be as high as 54%. With some exceptions, the chamfered orifices show a similar behavior as the rounded ones but with generally lower discharge coefficients. Nevertheless, a chamfered inlet yields lower pressure losses than a sharp-edged inlet. The obtained experimental data were used to develop two correlations for the discharge coefficient as a function of geometrical as well as flow properties. KW - Compressor KW - Gas turbine engines KW - Turbine components KW - Boundary layer development KW - Fluid dynamics KW - Heat transfer KW - Measurement techniques KW - Film cooling KW - Heat transfer phenomena Y1 - 2018 U6 - https://doi.org/10.1115/1.4039842 VL - 140 IS - 7 CY - ASME ER - TY - GEN A1 - Frank, Lena A1 - Rödder, Maximilian A1 - Neef, Matthias A1 - Adam, Mario T1 - Heizung, Lüftung, Weiße Ware - Ein integriertes Systemkonzept für das Haus der Zukunft T2 - KI Kälte Luft Klimatechnik N2 - In energieeffizienten Gebäuden spielt der Bedarf an Energie für die Raumheizung gegenüber der benötigten Energie für Warmwasser und zum Antrieb elektrischer Geräte eine zusehends untergeordnete Rolle. Die thermische Energie für elektrische Haushalts­geräte, wie Waschmaschine, Kühlschrank etc., wird für gewöhnlich dezentral im Gerät erzeugt. Vor diesem Hintergrund ist das Ziel eines Forschungsprojekts der Bau und der Test eines Funktionsmusters zur funktionalen und energetischen Kopplung der Haushaltsgeräte und der Heizungs- und Lüftungstechnik des Gebäudes. Grundgedanke dabei ist die Nutzung von Synergien bei Komponenten und Wärmeströmen, wie der Wärmepumpe als Kälteaggregat für den Kühlschrank, und die effiziente Nutzung von Abwärme der Haushaltsgeräte für die Warmwasserbereitung und Raumheizung. KW - Energieeffizienz KW - energiBUS4home Y1 - 2018 SN - 1865-5432 VL - 54 IS - 11 SP - 50 EP - 56 PB - Hüthig ER - TY - JOUR A1 - Bonk, Christian Dirk A1 - Laux, Christoph A1 - Rödder, Maximilian A1 - Neef, Matthias T1 - Design of a 1 KW Organic Rankine Cycle for Teaching and Research Issues JF - Energy Procedia N2 - This paper deals with the design of a micro-scale ORC plant for teaching and research including the development of an automated control concept. The aim is to provide a safe and environmentally acceptable micro-scale heat engine, which can be developed, implemented and used in university labs for the education of students as well as for small research projects. The test rig allows the support of several learning outcomes on a multi-disciplinary level particularly for the implementation and simulation of small power systems. Special attention was given to the organic working fluid characteristics and its selection process. In addition to the above-mentioned performance goals, favourable safety properties and low global warming potential were decisive in the selection of the novel organic fluid called 3M™ Novec™ 649. The performance and the fluid behaviour of Novec 649 in a micro-scale power cycle are of major interest and the research goal for the test rig presented in this paper. Due to the expected power output of 1 kW, a scroll expander was chosen as the generator drive for the micro plant. In order to design the major parts of the ORC, the thermodynamic simulation software EBSILON®Professional was used. The supply temperature was set to 140 °C. As a result of the simulation, feasible expander inlet pressures spread from 5.5 bar to 8.5 bar. This leads to thermal efficiencies of the ORC in the order of 5 %. Adding a recuperator to the cycle system decreases the operating pressure range but in the end, the thermal efficiency can be increased by 1.5 %-points up to 6.2 %. Finally, an automated control concept is introduced, where the pump is controlled via the fill level measurement system. KW - EBSILON®Professional KW - Micro-Scale ORC Plant KW - Teaching KW - Research KW - Automated Control Concept Y1 - 2017 U6 - https://doi.org/10.1016/j.egypro.2017.09.117 VL - 129 SP - 931 EP - 938 PB - Elsevier ER - TY - JOUR A1 - Neef, Matthias A1 - Zielke, Thomas A1 - Fussenecker, Claudia T1 - „Engineering Conferences“: Wissenschaftlich Kommunizieren im Master JF - Die Neue Hochschule Y1 - 2017 VL - 58 IS - 3 ER - TY - JOUR A1 - Roedder, Maximilian A1 - Neef, Matthias A1 - Laux, Christoph A1 - Priebe, Klaus-P. T1 - Systematic Fluid Selection for Organic Rankine Cycles and Performance Analysis for a Combined High and Low Temperature Cycle JF - Journal of Engineering for Gas Turbines and Power N2 - The organic Rankine cycle (ORC) is an established thermodynamic process that converts waste heat to electric energy. Due to the wide range of organic working fluids available the fluid selection adds an additional degree-of-freedom to the early design phase of an ORC process. Despite thermodynamic aspects such as the temperature level of the heat source, other technical, economic, and safety aspects have to be considered. For the fluid selection process in this paper, 22 criteria were identified in six main categories while distinguishing between elimination (EC) and tolerance criteria (TC). For an ORC design, the suggested method follows a practical engineering approach and can be used as a structured way to limit the number of interesting working fluids before starting a detailed performance analysis of the most promising candidates. For the first time, the selection process is applied to a two-stage reference cycle, which uses the waste heat of a large reciprocating engine for cogeneration power plants. It consists of a high temperature (HT) and a low temperature (LT) cycle in which the condensation heat of the HT cycle provides the heat input of the LT cycle. After the fluid selection process, the detailed thermodynamic cycle design is carried out with a thermodynamic design tool that also includes a database for organic working fluids. The investigated ORC cycle shows a net thermal efficiency of about 17.4% in the HT cycle with toluene as the working fluid and 6.2% in LT cycle with isobutane as the working fluid. The electric efficiency of the cogeneration plant increases from 40.4% to 46.97% with the both stages of the two-stage ORC in operation. KW - Gas Turbines KW - Cycle Innovations KW - Energy KW - Power systems KW - Fluids Y1 - 2016 U6 - https://doi.org/10.1115/1.4031361 VL - 138 IS - 031701 EP - 3 PB - ASME ER - TY - JOUR A1 - Wolter, Nina A1 - Zekorn, Thomas A1 - Neef, Matthias T1 - Stationäre thermodynamische Prozesssimulationen am Beispiel eines Industriekraftwerks JF - BWK: das Energie-Fachmagazin N2 - Um bauliche Veränderungen in bestehenden Kraftwerksprozessen auf ihre Wirkungsweise untersuchen und thermodynamisch beziehungsweise wirtschaftlich bewerten zu können, werden thermische Kraftwerksprozesse mit geeigneter Simulationssoftware abgebildet und in verschiedenen Detaillierungsstufen ausgelegt oder nachgerechnet. Im Folgenden wird ein Weg aufgezeigt, wie mit Hilfe einer stationären Simulationssoftware die Gesamtjahresbilanz eines Kraftwerks vorausberechnet werden kann. Mit Hilfe von Prozessdaten aus Vorjahren wird nachgewiesen, dass das Berechnungsmodell das bestehende Kraftwerk mit einer Abweichung von weniger als drei Prozent bezüglich erzeugter elektrischer Leistung und Brennstoffeinsatz und bei bekannter Dampfproduktion abbilden kann. Das so verifizierte Modell kann zur Untersuchung von Zubaumaßnahmen oder Veränderungen im Kraftwerksprozess eingesetzt werden. KW - Energiebilanz KW - Kraftwerk Y1 - 2016 VL - 68 IS - 6 SP - 6 EP - 10 ER - TY - CHAP A1 - Laux, Christoph A1 - Gotter, Andreas A1 - Neef, Matthias T1 - Experimental investigation of a low pressure steam Rankine cycle for waste heat utilization of internal combustion engines T2 - Proceedings of the 5th International Seminar on ORC Power Systems N2 - High heat losses via exhaust gas and coolant in internal combustion engines (ICE) are the basis for numerous investigations regarding downstream processes for power generation. The most promising concepts are Organic Rankine Cycles (ORC) and Steam Rankine Cycles (SRC). In previous work of the Center of Innovative Energy Systems, Düsseldorf (Germany), the technical and economic feasibility of a low pressure SRC has been investigated and the advantages in comparison to organic Rankine cycles are highlighted. A distinctive feature of the cycle is the use of the ICE coolant heat for evaporation, which limits the cycles maximum steam pressure to values below atmospheric pressure. This work presents first results of a test rig with data reconciliation according to DIN 2048 to validate the simulation results and design calculations. As a basis for the experimental investigations, a gas fired CHP plant was selected. The design of the test rig is optimized for the operation in the laboratory, where the coolant heat is emulated by a tempering device and the exhaust heat of the CHP plant is emulated by a gas burner. With the designed test rig, it is possible to control the volume flow and the temperatures of the coolant and exhaust gas, so that different load conditions of the gas fired CHP plant can be investigated. For initial tests, the turbine in the SRC is replaced by a throttle to achieve the pressure drop of the turbine. The experimental results show, that the exhaust and coolant heat of a 36 kWel CHP plant can be emulated and the performance expectations of the cycle can be met in stable steady-state conditions. Based on the measurement results and the turbine design calculations an electric power output of the cycle of 3.8 kW will be possible, which results in a cycle efficiency of about 6.5 % and an increase of the electrical power output of the CHP plant of about 10 %. The results show that the plant concept is technically feasible and, with further optimization, also represents an alternative to ORC plants in terms of increasing the efficiency of a cogeneration plant. Y1 - 2019 SN - 978-90-9032038-0 PB - The National Technical University of Athens (NTUA) CY - Athens ER - TY - CHAP A1 - Kramer, Tim A1 - Lerner, Igor A1 - Sacher, Patrick A1 - Neef, Matthias A1 - Baier, André ED - Dederichs-Koch, Andrea ED - Mohnert, Andrea ED - Kammasch, Gudrun T1 - Blue Engineering: Was ist das und wie gelingt die Implementierung an meiner Hochschule? T2 - Diversität und Kulturelle Vielfalt - Differenzieren, Individualisieren - oder Integrieren? Wege zu technischer Bildung : Referate der 13. Ingenieurpädagogischen Regionaltagung 2018 and der Hochschule Bochum vom 7.-9. Juni 2018 KW - Blue Engineering KW - Diversität Y1 - 2018 SN - 978-3-9818728-2-8 PB - Ingenieur-Pädagogische Wissensgesellschaft (IPW) CY - Berlin ER -