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This talk gives an overwiew about the material and physico chemical characterisation of materials developed for the EU founded project PlasticsFate. Particles in 1st and 2nd sample set are presented next to their characterisatin and documentation in data sheets. Some materials are prepared for reference material and used in an interlaboratory comparison. Results are briefly discussed.
In diesem Vortrag geht es um eine Übersicht über die Thematik der Mikroplastik, Was ist Mikroplastik, wie entsteht es und wo kommt es her. Es wird beschrieben wie eine repräsentative Probenahme erfolgen kann und wie welche Herausforderungen bei der Probenvorbereitung existieren. Die Detektion wird ausführlich beschrieben, sowohl mit Partikelanzahl als auch Masse. Im weiteren werden erste Referenzmaterialien und ihre Anwendung in internationalen Ringversuchen beschrieben. Der zweite Teil zeigt die Normungsaktivitäten im Bereich der Mikroplastik.
To accelerate the hydrogen uptake in Europe the project KICstartH2 funded by the European Union arranged the Joint European Summer School (JESS) that deals with several topics around hydrogen. A topic in this framework is the transport and storage of energy by hydrogen. Here cryogenic energy carriers are seen as having great potential. This is because they allow significantly higher volumetric energy densities to be achieved than when these energy carriers are stored at typical temperatures on Earth. This is important for numerous energy-intensive applications, such as those found in all transport sectors. Important cryogenic energy carriers include liquefied hydrogen (LH2) and liquefied natural gas (LNG). This presentation deals with the consequences of an accidental release of a cryogenic liquid and the consequences of a fire affecting a tank.
To accelerate the hydrogen uptake in Europe the project KICstartH2 funded by the European Union arranged the Joint European Summer School (JESS) that deals with several topics around hydrogen. A topic in this framework is the transport and storage of energy by hydrogen. Here cryogenic energy carriers are seen as having great potential. This is because they allow significantly higher volumetric energy densities to be achieved than when these energy carriers are stored at typical temperatures on Earth. This is important for numerous energy-intensive applications, such as those found in all transport sectors. Important cryogenic energy carriers include liquefied hydrogen (LH2) and liquefied natural gas (LNG). This presentation focuses on the physical parameters and methods relevant to the storage of cryogenic fluids.
Fibre Optic Sensing @BAM
(2024)
The undesirable presence of micro and nanoplastics in our environment and in food is now common knowledge. However, it is unclear whether serious dangers and risks are posed by nanoplastics. A scientifically based reliable determination of the type and quantity of nanoplastics in complex matrices is of considerable importance for the future sustainable use of polymers. Here, reference materials help in the determination of nanoplastics. In particular, colloidally stable aqueous dispersions of nanoplastics appear suitable for this purpose. We report on the current status of the development of nanoplastics as reference materials. A detailed example of reference materials for characterizing nanoplastics is provided in the form of aqueous dispersion of polypropylene. The nanoplastics samples are colloidal stable for at least two years at ambient conditions. A low zeta potential of -35 mV at a neutral pH value provides stability. An overview of their colloidal properties in different environmental conditions is presented. Next, polyethylene nanoplastics will be compared to polypropylene nanoplastics. Nanoplastics consisting of poly(ethylene terephthalate) will be discussed and finally, we report on poly(L-lactic acid) as a typical and important representative of biodegradable polymers.
Numerical Simulation Of Cryogenic Liquid Hydrogen Tanks With Multilayer Insulation Exposed to Fire
(2024)
In the ongoing energy transition, hydrogen has emerged as a promising alternative energy carrier with a reduced environmental impact. Among the possible solutions to store hydrogen onboard vehicles, cryogenic tanks equipped with multilayer insulation (MLI) appear to be one of the most effective in ensuring high volumetric energy density. MLI systems consist of several layers of low-emissivity material (radiative layers), typically aluminum or aluminum-coated polyester, interleaved with low thermal conductivity spacers to avoid direct contact between the radiative layers. In cryogenic tank applications, these are enclosed within the vessel double-walled shell, working under high-vacuum conditions. Among the insulation systems available nowadays, MLI-based ones have the smallest volume requirements and the lowest weight. Thanks to these features, MLI appears as the preferable choice in sectors where space and weight constraints play a crucial role (e.g., in the transportation sector).
The widespread deployment of LH2 new technologies poses also challenging questions related to the hazardous properties of hydrogen. The accidental loss of integrity of cryogenic LH2 tanks might lead to extremely dangerous phenomena, such as Boiling Liquid Expanding Vapour Explosions (BLEVE), Fireball, and Rapid Phase Transition (RPT). One potential scenario that could give rise to this situation is exposure to an external heat source such as a fire triggered by a road accident. Real-scale fire test results suggest that the insulation performance of MLI systems may undergo severe degradation when these are subjected to high temperatures, leaving the tank almost unprotected and leading to failure in a relatively short time.
In this framework, the availability of models able to simulate the tank response to fire exposure is crucial to ensure a safe design and support emergency response planning. Several CFD and lumped models originally developed for pressurized and atmospheric tanks were extended to cryogenic vessels. However, these provide results in line with experimental data only if the insulation system's equivalent thermal conductivity is fine-adjusted to higher values with respect to normal operating conditions. These models do not integrate, in fact, the description of MLI thermal degradation as a result of fire exposure, which was demonstrated to play a crucial role in determining the response of the cryogenic liquid hydrogen tank.
On the other hand, MLI heat transfer models currently available in the literature are suitable for normal operative conditions only and do not address the material behavior under fire exposure.
This work presents an innovative lumped model to simulate the thermal response of MLI-insulated cryogenic hydrogen tanks in fire scenarios. In particular, the proposed approach enables the prediction of MLI loss of insulation performances due to fire-induced thermal degradation, overcoming the limitations of currently available models.
The MLI degradation model is based on the well-established layer-by-layer approach and integrated with sub-models to estimate the material deterioration due to thermal load. Several sub-models were defined to account for different MLI materials. In particular, for polyester-based MLIs, the deterioration of each layer is defined by the apparent kinetic of thermal degradation retrieved from Thermo-Gravimetric-Analysis (TGA) tests. For aluminum-based MLI, each radiation layer is assumed to vanish when its temperature reaches the melting point of the material.
The model was applied to several case studies addressing different types of MLI (i.e., both polyester-based and aluminum-based ones) and fire scenarios to assess the effect on the heating rate and pressure build-up of the tank lading. The analysis allowed for the performance comparison of the studied MLIs, providing valuable information to support the emergency management of accidental scenarios involving liquid-hydrogen cryogenic tanks. Moreover, the results obtained can be used to define mitigation measures to protect the integrity of cryogenic tanks equipped with MLI.
Photophysical and mechanistic studies, the comparison of different emitter classes, and the rational design of the next generation of molecular and nanoscale reporters require quantitative photoluminescence measurements and the reliable determination of the key performance parameter photoluminescence quantum yield (QY), i.e., the number of emitted per absorbed photons. This is of special importance for all photoluminescence applications in the life and material sciences in the UV/vis/NIR/SWIR. To improve the reliability and comparability of photoluminescence and QY measurements across laboratories, pitfalls, achievable uncertainties, and material-specific effects related to certain emitter classes must be explored. Also, suitable protocols and reference materials are needed which have been validated in interlaboratory comparisons for different wavelength regions and transparent and scattering luminophores.[1] Based on absolute and relative photoluminescence measurements of functional dyes and nanomaterials like semiconductor quantum dots and rods, spectrally shifting lanthanide upconversion nanocrystals, perovskites, and YAG:Cer converter materials, reliable methods for determining QY of transparent and scattering luminophores, nonlinear emitters, and solid luminescent nanomaterials have been developed.[2,3] Thereby, material- and method-related uncertainties of relative and absolute QY measurements and achievable uncertainties could be quantified for linear and nonlinear UV/vis/NIR/SWIR emitters and lately for also luminescent and scattering materials and solid phoshors, here in an interlaboratory comparison of three labs utilizing integrating sphere spectroscopy.[4,5] In addition, to provide simple tools for a better comparability of QY measurements, recently, a first set of UV/vis/NIR quantum yield standards has been developed and certified with complete uncertainty budgets.[6] In the following, the outcome of these studies will be presented, thereby addressing common pitfalls and providing recommendations on the performance of reliable QY measurements of linear and non-linear emitters in transparent, scattering, and solid samples.
Wasserstoff leistet als Energieträger der Zukunft einen entscheidenden Beitrag zur nachhaltigen Energieversorgung. Der Transport wird vorwiegend durch das europäische Ferngasleitungsnetz erfolgen. Bisherige Untersuchungen zeigen, dass bisher verwendete Rohrstähle grundsätzlich für den Wasserstofftransport geeignet sind. Diese Eignung ist nicht direkt auf Reparaturfragestellungen im Betrieb übertragbar, da Schweißungen aus technisch-ökonomischen Gründen oft unter fortwährendem Gasfluss durchgeführt werden.
Ein im Erdgasnetz angewandtes Konzept ist das Anbohren druckführender Pipelines („Hot Tapping“). Dazu werden Zylinderhalbschalen zuerst durch Längs- und dann per Rohrrundnähten an die Pipeline geschweißt. Essenziell ist dabei die maßgeschneiderte Wärmeeinbringung, um das „Durchbrennen“ in die Pipeline zu vermeiden. Für zukünftige Wasserstoffpipelines liegt der Fokus u.a. auf dünnwandigen Leitungen. Im Gegensatz zu Erdgas, führen die beim Schweißen erreichten hohen Temperaturen an der Innenseite der Pipeline zu einer zusätzlichen Wasserstoffaufnahme in den Rohrstahl mit möglicher Materialdegradation.
Zur praktischen Lösung der Fragestellung, sind internationale Aktivitäten im Gang. Diese umfassen bspw. die Möglichkeiten und Weiterentwicklung von realistischen Prüfkonzepten (u.a. durch maßstäbliche Bauteilversuche). Dazu untersucht die Bundesanstalt für Materialforschung und -prüfung (BAM) in einem DVGW-geförderten Kooperationsprojekt mit Gasnetzbetreibern, die Frage der Übertragbarkeit der Schweißkonzepte der Erdgastechnik auf zukünftiger Wasserstoffpipelines.