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Die Planung und der Bau von Reinräumen sind komplexe Vorgänge, die ein hohes Maß an logistischer und fachlicher Kompetenz erfordern. Insbesondere ist die stetige Steigerung der Reinheit bis zur Inbetriebnahme eine wesentliche Voraussetzung für den späteren bestimmungsgemäßen Betrieb. Die Regelwerke und hier insbesondere die VDI 2083 liefert klare Vorgaben für den Planungsablauf. Um die Umsetzung der Richtlinie in die Praxis jedoch einfacher und unmissverständlich zu gestalten, sollte ein dezidierter Qualitätsplan vor jedem Projektbeginn ausgearbeitet werden. Dieser soll in Abhängigkeit des Baufortschritts die Bau- und Schutzmaßnahmen koordinieren und klare Regeln für die am Bau Beteiligten festlegen. Um unvorhergesehene Fehler und deren Folgen zu minimieren bietet sich die Fehlermöglichkeits- und Einflussanalyse (FMEA) als Bestandteil des Qualitätsplans an. Hierdurch werden mögliche Fehler beschrieben und die Risiken erfasst und vorsorglich minimiert. Die Risikoprioritätszahl (RPZ) ist dabei ein Maß für den möglichen Schaden. Die FMEA sorgt dafür, dass die festgelegten Maßnahmen mit hoher Wirksamkeit umgesetzt werden können.
Die Erstellung der FMEA betrifft alle Gewerke beim Bau des Reinraums, daher sollten die Inhalte in gemeinsamen Besprechungen aller Verantwortlichen für jedes Bauvorhaben individuell erstellt werden. Dadurch ist zusätzlich das Bewusstsein zur Reinhaltung bei allen Gewerken gegeben. Der Bauleitung obliegt die durchgehende und verantwortungsbewusste Umsetzung des Qualitätsplans.
Performance enhancing study for large scale PEM electrolyzer cells based on hydraulic compression
(2017)
This experimental work deals with the preparation and investigation of PEM fuel cell electrodes, which are obtained using Graphene Related Material (GRM) serving as catalyst support material for platinum nanoparticles. The applied GRM belong to the group of carbon nanofibers and exhibits a helical-ribbon structure with dimensions of 50 nm in diameter and an average length up to a few µm. Furthermore, utilized GRM provide a superior graphitisation degree of about 100 %, which leads to both high corrosion resistance and low ohmic resistance. Material stability plays one of the main roles for long term fuel cell operation, whereby a great electrical catalyst contact combined with high specific surface area yields in high fuel cell performances.
Prior to GRM dispersion and deposition onto a gas diffusion layer, the graphene structures are functionalized by oxygen plasma treatment. Through this step, functional oxygen groups are generated onto the GRM outer surface providing an improved hydrophilic behaviour and facilitating the GRM suspension preparation. In addition, the oxygen groups act as anchors for platinum nanoparticles which are subsequently deposited onto the GRM surface through a pulse electrodeposition process.
Membrane electrode assemblies produced with the prepared electrodes are investigated in-situ in a PEM fuel cell test bench.
Due to high power density and superior efficiency, polymer electrolyte membrane fuel cells (PEMFC) are believed to play a significant role for carbon dioxide emissions free electrical energy systems in the future. Unlike in Carnot processes, chemical energy in the form of hydrogen and oxygen is converted directly into electrical energy without a further process step. One issue in the development of PEMFCs for mobile or stationary applications is the utilization of rare and expensive catalyst material like platinum within the membrane electrode assembly (MEA) see figure 1. In addition, the objective is to reduce production costs and to increase the lifetime of PEMFC. One approach to improve PEMFCs is the development of intelligent electrode architectures. However, cost effective high performance materials are necessary to reach the development targets.
This experimental work deals with the preparation and investigation of PEM fuel cell electrodes, which are obtained using Graphene Related Material (GRM) serving as catalyst support material for platinum nanoparticles. The applied GRM belong to the group of carbon nanofibers and exhibits a helical-ribbon structure with dimensions of 50 nm in diameter and an average length up to a few µm. Furthermore, utilized GRM provide a superior graphitisation degree of about 100 %, which leads to both high corrosion resistance and low ohmic resistance. Material stability plays one of the main roles for long term fuel cell operation, whereby a great electrical catalyst contact combined with high specific surface area yields in high fuel cell performances.
Prior to GRM dispersion and deposition onto a gas diffusion layer, the graphene structures are functionalized by oxygen plasma treatment. Through this step, functional oxygen groups are generated onto the GRM outer surface providing an improved hydrophilic behaviour and facilitating the GRM suspension preparation. In addition, the oxygen groups act as anchors for platinum nanoparticles which are subsequently deposited onto the GRM surface through a pulse electrodeposition process.
Membrane electrode assemblies produced with the prepared electrodes are investigated in-situ in a PEM fuel cell test bench.
This work deals with the preparation and investigation of polymer electrolyte membrane fuel cell (PEMFC) electrodes, which are obtained using gas diffusion layers coated with graphene related material (GRM) serving as a catalyst support for platinum nanoparticles. PEMFC electrocatalysts have been prepared by pulsed electrochemical deposition of platinum particles from hexachloroplatinic acid. Prior to GRM decoration with platinum, the graphene structures are functionalized by oxygen plasma treatment. This leads to oxygen containing functional groups on the GRM outer surface, providing an improved hydrophilic behavior, thus favoring the Pt deposition process. Membrane electrode assemblies (MEAs) with the so prepared electrodes are investigated in-situ in our fuel cell test system. Polarization plots (in-situ cell performance) using these MEAs have been tested under different operational conditions.
To further increase platinum utilisation in PEM fuel cells CNFs are investigated as catalyst support material due to the CNF’s high specific surface area. Furthermore, CNFs provide suitable properties concerning corrosion resistance as well as electrical conductivity in contrast to conventional carbon supports.
This work presents the results of an electrode preparation procedure based on O2 plasma activated CNFs. The plasma treatment leads to CNF dispersibility in alcohol/water for a spray coating process. Furthermore, O2 plasma activation enhances metal deposition on the CNF’s surface. Pulse plating procedure as well as wet chemical metal synthesis have been used for particle deposition. For pulse plating a potentiostat/galvanostat type MMates 510 AC from Materials Mates, Italy has been used. Electrode morphology has been determined in SEM type XL 30 ESEM from Philips, The Netherlands.
Platinum nanoparticles electrodeposition on carbon nanofibers (CNF) support has been performed with the purpose to obtain electrodes that can be further used especially in a polymer electrolyte membrane fuel cell (PEMFC). A pretreatment of CNF is required in order to enhance the surface energy, which simultaneously improves handling and wettability as well as interaction with the platinum cations. This step was performed using oxygen plasma functionalization. To produce CNF supported Pt catalysts, an electrochemical method was applied and the deposition parameters were adjusted to obtain nanosized platinum particles with a good distribution onto the graphitic surface. The morphology and structure of the obtained particles were investigated by scanning electron microscopy combined with energy dispersive X-Ray spectroscopy. The amount of deposited platinum was established using thermogravimetrical measurements. Cyclic voltammetry performed in 0.5 M H2SO4 solution was applied for determining the electrochemical surface area (ECSA) of the obtained electrodes.The functionalization degree of the CNF outer surface has a strong influence on the structure, distribution and amount of platinum particles. Moreover, the current densities, which were set for the deposition process influenced not only the particles size but also the platinum amount. Applying an oxygen plasma treatment of 80 W for 1800 s, the necessary degree of surface functionalization is achieved in order to deposit the catalyst particles. The best electrodes were prepared using a current density of 50 mA cm-2 during the deposition process that leads to a homogenous platinum distribution with particles size under 80 nm and ECSA over 6 cm2
In vielen TGA-Büros werden bereits heute mehr oder weniger unbewusst wichtige Vorteile der BIM-Methode genutzt, als „Little BIM“ oder Büro-intern als „Big BIM“ bzw. „Closed-BIM“.
Große Potenziale von BIM lassen sich aber erst erschließen, wenn alle relevanten Akteure für die Planung, Errichtung und den Betrieb Software übergreifend an und mit einem gemeinsamen Datenmodell arbeiten (Open BIM).
Der TGA kommt beim BIM eine Schlüsselrolle zu, muss dafür aber viel früher als bisher in die Gebäudeplanung einbezogen werden.
Eine große Herausforderung für die Verbreitung von BIM ist die digitale Transformation der kleinteiligen TGA-Branche in den Segmenten Planung und Installation. Ein wichtiger Schritt dafür ist eine zielgerichtete Weiterbildung, um den individuellen Schulungs- und Investitionsbedarf zu ermitteln.
Nachhaltigkeit von intelligenten Gebäuden - Ein Blick auf die Gesetzgebungen und Praxismöglichkeiten
(2023)
Gebäude sind durch ihre Herstellung und den Betrieb für einen erheblichen Teil der CO2-Emissionen in Europa verantwortlich. Die EU und Deutschland wollen durch milliardenschwere Maßnahmenpakete diese Emissionen bis zum Jahr 2045 (Deutschland) bzw. 2050 (EU) auf null reduzieren. Neben der Gebäudehülle als maßgeblicher Faktor für die Wärmebilanz zum Heizen und Kühlen spielt die Gebäudeautomation eine wichtige Rolle. Wie Gebäude intelligenter und smarter werden und wie sich das auf die Energieeffizienz auswirkt, soll im Folgenden betrachtet werden.
Zur Planung und zum Bau von Reinräumen gibt es zwei Normen (VDI 2083 „Reinraumtechnik“ und ISO 14644 „Reinräume und zugehörige Reinraumbereiche“). Beide Normen fordern einen Qualitätsplan, der aber nicht eindeutig definiert ist. In der Praxis bedeutet dies, dass sich die ausführenden Planer und Gewerke nicht auf eine allgemein gültige Norm für einen Qualitätsplan verlassen können. Genau an dieser Stelle setzt eine Masterarbeit an und definiert einen möglichen Qualitätsplan mit Zwischenzielen und den dafür erforderlichen Maßnahmen. Unter anderem wird zur Sicherstellung der einzelnen Baufortschritte und zur Einhaltung des Reinraumkonzepts die Methodik der Fehlermöglichkeits- und Einflussanalyse (FMEA) eingeführt. Diese Methodik wird bereits in der Automobilindustrie angewendet und umfasst unter anderem auch die sogenannte Risikoprioritätszahl (RPZ), die das Gesamtrisiko eines möglichen Fehlers in Planung und Bau beziffert. cci Zeitung hat bei Prof. Christian Fieberg, seit März 2017 Professor für Gebäudetechnik, und M. Sc. Lea Klaßen, Verfasserin der Masterarbeit, beide Westfälische Hochschule Gelsenkirchen, zu diesem Thema nachgefragt.
An energy economy with high share of renewable but volatile energy sources is dependent on storage strategies in order to ensure sufficient energy delivery in periods of e.g. low wind and/or low solar radiation. Hydrogen as environmental friendly energy carrier is thought to be an appropriate solution for large scale energy storage. In 2011 the NOW (national organisation for hydrogen in Germany) calculated the demand for hydrogen energy systems as positive (0.8 GW to 5.25 GW) and negative supply for varying power demand (0.68 to 4.3 GW) for the German energy economy in 2025. Due to its dynamic behaviour on load changes polymer electrolyte membrane fuel cells (PEMFC) as well as water electrolyser systems (PEMEL) can play a significant role for large scale hydrogen based storage systems. In this work a novel design concept for modular fuel cell and electrolyser stacks is presented with single cells in pockets surrounded by a hydraulic medium. This hydraulic medium introduces necessary compression forces on the membrane electrode assembly (MEA) of each cell within a stack. Furthermore, ideal stack cooling is achieved by this medium. Due to its modularity and scalability the modular stack design with hydraulic compression meets the requirements for large PEMFC as well as PEMEL units. Small scale prototypes presented in this work illustrate the potential of this design concept.
In polymer electrolyte membrane fuel cells (PEMFC) noble metal nano particles are deposited on graphitic supports serving as electrocatalysts for devices with high power density. In this study anodes are analysed with low platinum loading of about 0.1 mg cm-2. These electrodes are prepared by carbon nano fibres (CNF) decorated with platinum nano particles. For electrode manufacturing two sorts of fibres, which are produced in an industrial scale, are used with different graphitisation degree and surface area. CNF layers are applied on commercially available graphitic substrate by spray coating which leads to a porous structure with high surface area. Subsequently, platinum deposition is achieved by pulsed electroplating for an improved platinum utilisation in PEMFC electrodes. Spray coating and platinum deposition are assisted by a previous oxygen plasma activation process. Prepared anode material is characterised by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction spectroscopy (XRD), X-ray fluorescence spectroscopy (XRF) and thermogravimetry (TGA). Electrochemical analyses (cyclic voltammetry and corrosion test) are carried out in 0.5 M sulphuric acid. The effect of graphitisation degree of carbon nano fibres on the performance of prepared electrodes is investigated in-situ in a PEM fuel cell test bench.
In this experimental work polymer electrolyte membrane fuel cell (PEMFC) electrodes are analysed, which are prepared by the use of two sorts of carbon nano fibres (CNF) serving as support material for platinum nano particles. Those CNFs, which are heat treated subsequently to their production, have a higher graphitisation degree than fibres as produced. The improved graphitisation degree leads to higher electrical conductivity, which is favourably for the use in PEMFC electrodes. Samples have been analysed, in order to determine graphitisation degree, electrical conductivity, as well as morphology and loading of the prepared electro catalyst. Membrane electrode assemblies manufactured from prepared electrodes are analysed in-situ in a PEM fuel cell test environment. It has been determined that power output for samples containing CNFs with higher graphitisation degree is increased by about 13.5%.