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Technical assessment of Brayton cycle heat pumps for the integration in hybrid PV-CSP power plants
No full textThe hybridization of Concentrated Solar Power (CSP) and Photovoltaics (PV) systems is a promising approach to reduce costs of solar power plants, while increasing dispatchability and flexibility of power generation. High temperature heat pumps (HT HP) can be utilized to boost the salt temperature in the thermal energy storage (TES) of a Parabolic Trough Collector (PTC) system from 385 °C up to 565 °C. A PV field can supply the power for the HT HP, thus effectively storing the PV power as thermal energy. Besides cost-efficiently storing energy from the PV field, the power block efficiency of the overall system is improved due to the higher steam parameters. This paper presents a technical assessment of Brayton cycle heat pumps to be integrated in hybrid PV-CSP power plants. As a first step, a theoretical analysis was carried out to find the most suitable working fluid. The analysis included the fluids Air, Argon (Ar), Nitrogen (N2) and Carbon dioxide (CO2). N2 has been chosen as the optimal working fluid for the system. After the selection of the ideal working medium, different concepts for the arrangement of a HT HP in a PV-CSP hybrid power plant were developed and simulated in EBSILON®Professional. The concepts were evaluated technically by comparing the number of components required, pressure losses and coefficient of performance (COP)
Template bacteria-free fabrication of surface imprinted polymer-based biosensor for E. coli detection using photolithographic mimics: Hacking bacterial adhesion
Full text linkAs one class of molecular imprinted polymers (MIPs), surface imprinted polymer (SIP)-based biosensors show great potential in direct whole-bacteria detection. Micro-contact imprinting, that involves stamping the template bacteria immobilized on a substrate into a pre-polymerized polymer matrix, is the most straightforward and prominent method to obtain SIP-based biosensors. However, the major drawbacks of the method arise from the requirement for fresh template bacteria and often non-reproducible bacteria distribution on the stamp substrate. Herein, we developed a positive master stamp containing photolithographic mimics of the template bacteria (E. coli) enabling reproducible fabrication of biomimetic SIP-based biosensors without the need for the “real” bacteria cells. By using atomic force and scanning electron microscopy imaging techniques, respectively, the E. coli-capturing ability of the SIP samples was tested, and compared with non-imprinted polymer (NIP)-based samples and control SIP samples, in which the cavity geometry does not match with E. coli cells. It was revealed that the presence of the biomimetic E. coli imprints with a specifically designed geometry increases the sensor E. coli-capturing ability by an “imprinting factor” of about 3. These findings show the importance of geometry-guided physical recognition in bacterial detection using SIP-based biosensors. In addition, this imprinting strategy was employed to interdigitated electrodes and QCM (quartz crystal microbalance) chips. E. coli detection performance of the sensors was demonstrated with electrochemical impedance spectroscopy (EIS) and QCM measurements with dissipation monitoring technique (QCM-D)
Analytical methods for in-line characterization of beer haze
No full textIn most beers, producers strive to minimize haze to maximize visual appeal. To detect the formation of particulates, a measurement system for sub-micron particles is required. Beer haze is naturally occurring, composed of protein or polyphenol particles; in their early stage of growth their size is smaller than 2 µm. Microscopy analysis is time and resource intensive; alternatively, backscattering is an inexpensive option for detecting particle sizes of interest
Low-Voltage DC Training Lab for Electric Drives - Optimizing the Balancing Act Between High Student Throughput and Individual Learning Speed
No full textAfter a brief introduction of conventional laboratory structures, this work focuses on an innovative and universal approach for a setup of a training laboratory for electric machines and drive systems. The novel approach employs a central 48 V DC bus, which forms the backbone of the structure. Several sets of DC machine, asynchronous machine and synchronous machine are connected to this bus. The advantages of the novel system structure are manifold, both from a didactic and a technical point of view: Student groups can work on their own performance level in a highly parallelized and at the same time individualized way. Additional training setups (similar or different) can easily be added. Only the total power dissipation has to be provided, i.e. the DC bus balances the power flow between the student groups. Comparative results of course evaluations of several cohorts of students are shown
Passive thermal control by integration of phase change material into additively manufactured structures
No full textOptical Instruments require an extremely stable thermal surrounding to prevent loss of data quality by misalignments of the instrument components resulting from material deformation due to temperature f luctuations (e.g. from solar intrusion). Phase Change Material (PCM) can be applied as a thermal damper to achieve a more uniform temperature distribution. The challenge of this method is, among others, the integration of PCM into affected areas. If correctly designed, incoming heat is latently absorbed during phase change of the PCM, i.e. the temperature of a structure remains almost constant. In a cold phase, the heat during phase change is released again latently until the PCM returns to its original state of aggregation. Thus, the structure is thermally stabilized. At FH Aachen– University of Applied Sciences research is conducted to apply PCM directly into the structures of affected components (baffles, optical benches, electronic boxes, etc.). Through the application of Additive Manufacturing, the necessary voids are directly printed into these structures and filled later with PCM. Additive Manufacturing enables complex structures that would not have been possible with conservative manufacturing methods. A corresponding Breadboard was developed and manufactured by Selective Laser Melting (SLM). The current state of research includes the handling and analysis of the Breadboard, tests and a correlation of the thermal model. The results have shown analytically and practically that it is possible to use PCM as an integral part of the structure as a thermal damper. The results serve as a basis for the further development of the technology, which should maximize performance and enable the integration of PCM into much more complex structures
The impact of guide tubes on flow separation in rocket nozzles
No full textRocket engine test facilities and launch pads are typically equipped with a guide tube. Its purpose is to ensure the controlled and safe routing of the hot exhaust gases. In addition, the guide tube induces a suction that effects the nozzle flow, namely the flow separation during transient start-up and shut-down of the engine. A cold flow subscale nozzle in combination with a set of guide tubes was studied experimentally
to determine the main influencing parameters
Designing for Focus : ein Hilfsmittelsystem für Kinder mit AD(H)S
No full textDas Projekt widmet sich dem Thema der Aufmerksamkeitsdefizit-Hyperaktivitätsstörung (ADHS) und Aufmerksamkeitsdefizitstörung (ADS) im Kindesalter. Es setzt sich dabei mit den täglichen Herausforderungen auseinander, mit denen diese Kinder sowohl im Lernprozess als auch in der familiären Beziehungsdynamik konfrontiert sind. Der entwickelte Konzentrationsbegleiter und das dazugehörige Set basieren auf einer lerntherapeutischen Idee, die ein Gleichgewicht zwischen Konzentration und Entspannung erschafft. Das Gesamtsystem „MonKo“ bietet mit dem Konzentrationsbegleiter Unterstützung bei der Alltagsplanung, Priorisierung von Aufgaben und dem Umgang mit Reizen. Der Entspannungsteil des Sets präsentiert sich als „Schatzkiste“ mit sensorischen Spielzeugen und ist individuell von Therapeut:innen und Lehrkräften an die Bedürfnisse der Kinder anpassbar. Der Konzentrationsbegleiter in der Optik eines liebevollen Monsters soll den Kindern helfen, mit den Herausforderungen neuroatypischen Verhaltens umzugehen und erfolgreich in Schule und Alltag zu sein
Investigation of laser powder bed fusion parameters with respect to their influence on the thermal conductivity of 316L samples
No full textThe thermal conductivity of components manufactured using Laser Powder Bed Fusion (LPBF), also called Selective Laser Melting (SLM), plays an important role in their processing. Not only does a reduced thermal conductivity cause residual stresses during the process, but it also makes subsequent processes such as the welding of LPBF components more difficult. This article uses 316L stainless steel samples to investigate whether and to what extent the thermal conductivity of specimens can be influenced by different LPBF parameters. To this end, samples are set up using different parameters, orientations, and powder conditions and measured by a heat flow meter using stationary analysis. The heat flow meter set-up used in this study achieves good reproducibility and high measurement accuracy, so that comparative measurements between the various LPBF influencing factors to be tested are possible. In summary, the series of measurements show that the residual porosity of the components has the greatest influence on conductivity. The degradation of the powder due to increased recycling also appears to be detectable. The build-up direction shows no detectable effect in the measurement series
Gestaltung des Abschieds : wie Design bei der Transformation des Umgangs mit Tod und zur Förderung von Hospizarbeit unterstützen kann
No full textParēgoria, ein Trauerbegleitungsprojekt, wurde mit dem Ziel konzipiert, eine moderne Plattform für Trauernde zu schaffen. Der Name, abgeleitet vom altgriechischen "Trost", unterstreicht den Fokus auf Trost und Selbsthilfe. Die Konzeption richtet sich nach dem Grundprinzip, den Menschen und seine Trauer an erste Stelle zu stellen. Das Herzstück von Parēgoria ist die interaktive Plattform, die Trauernde unterstützen und vernetzen soll. Der Ansatz integriert minimalistisches Design, helle Farben und die gezielte Verwendung von Illustrationen, um eine freundliche Atmosphäre zu schaffen.
Die Anwendung ermöglicht ein personalisiertes Erlebnis für Mitglieder. Die Navigation ist intuitiv, basierend auf einem klaren Header, Seitenmenü und Footer. Parēgoria soll als Browseranwendung starten, um breite Zugänglichkeit sicherzustellen. Das übergeordnete Ziel besteht darin, nicht nur eine technologische Plattform zu schaffen, sondern eine unterstützende Gemeinschaft und ein umfassendes Ökosystem für Trauernde zu entwickeln. Parēgoria strebt an, die Wahrnehmung von Tod und Sterben in der Gesellschaft positiv zu beeinflussen und einen Raum für Austausch, Trost und persönliche Entwicklung zu schaffen
Digitaler Marktplatz : für Erzeuger:innen und Konsument:innen regionaler Produkte
No full textDigitaler Marktplatz für Erzeuger:innen und Verbraucher:innen regionaler Produkte. Das Ziel dieses Projekts ist es, solidarische Landwirtschaft (SoLaWi) zu digitalisieren, um eine zeitgemäße Alternative zu den bestehenden Kauf- und Abonnementprozessen zu schaffen. Die dabei entstandene App „KoHof" ermöglicht landwirtschaftlichen Betrieben, sich online zu präsentieren, Abonnements zu verwalten und neue Mitglieder zu gewinnen. Gleichzeitig bietet die Plattform Verbraucher:innen eine unkomplizierte Möglichkeit, passende Betriebe und dazugehörige Produkte in der Region zu finden sowie ihre Mitgliedschaft zu verwalten. Insgesamt strebt das Projekt "KoHof" danach, die Solidarische Landwirtschaft digital zu transformieren und eine neue Perspektive für die regionale Erzeugung von Lebensmitteln zu eröffnen. Durch diese innovative Plattform wird die Vernetzung zwischen Erzeugerinnen und Verbraucherinnen in der SoLaWi-Bewegung auf eine neue Stufe gehoben