TY - JOUR A1 - Rauchegger, C. A1 - Bayley, S. A1 - Schröder, Volkmar A1 - Thévenin, D. T1 - Dispersion of heavy gases - experimental results and numerical simulations JF - Process safety progress N2 - The hazardous potential of accidental heavy gas releases, especially those involving flammable and toxic gases, is widely known. In order to predict the area in which these gases are in hazardous concentrations, an estimation of the dispersion of these gases must be carried out. While the hazardous area for flammable heavy gases is determined by the lower flammability limit (ca. >1 vol%), the release of toxic heavy gases can result in a much larger hazardous area. Toxic gases, even in very low concentrations (ca. <3,000 ppm), have the potential to be highly damaging. State-of-the-art dispersion models, such as the VDI Guideline 3783, can be used to estimate the dispersion of heavy gases. However, VDI 3783 gives no method for the prediction of the height and width of a heavy gas cloud, which are both required for quantitative risk analysis as well as for a possible coupling of a Lagrangian particle model with the VDI 3783 heavy gas dispersion model. Therefore, further calculation methods were used to describe these dimensions and were evaluated against experimental studies of the length, width, and height of the heavy and neutral gas field. In addition to that the influence of the source height on the heavy gas dispersion was also examined KW - Process safety KW - Heavy gas KW - Numerical simulation KW - Explosion protection PY - 2015 DO - https://doi.org/10.1002/prs.11723 SN - 1066-8527 SN - 1547-5913 SN - 0278-4513 VL - 34 IS - 3 SP - 280 EP - 285 PB - Wiley InterScience CY - Hoboken, NJ AN - OPUS4-34756 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schröder, Jakob A1 - Mishurova, Tatiana A1 - Fritsch, Tobias A1 - Serrano Munoz, Itziar A1 - Evans, Alexander A1 - Sprengel, Maximilian A1 - Klaus, M. A1 - Genzel, C. A1 - Schneider, J. A1 - Bruno, Giovanni T1 - On the influence of heat treatment on microstructure and mechanical behavior of laser powder bed fused Inconel 718 JF - Materials Science & Engineering A N2 - A range of heat treatments have been developed for wrought Inconel 718 to obtain desired properties. For additively manufactured Inconel 718, the recently developed standard ASTM F3301 provides guidance for heat treatment of powder bed fusion specimens. Although this standard is based on standards developed for wrought Inconel 718, it does not include direct aging. Since direct aging reduces the number of processing steps, it can result in a post processing cost reduction if the desired properties are obtained. In this study, we characterized the microstructure and tensile behavior of Inconel 718 specimens produced by a laser powder bed fusion process. The specimens were heat treated according to two different routines after stress relieving: a full heat Treatment versus a one-step direct aging process. Differences in the resulting texture and grain morphology were observed. The ex-situ stress-strain behavior was broadly similar. However, a slight increase in yield strength was observed for the direct aged specimen. In order to understand this behavior, investigations with in-situ synchrotron Energy dispersive X-ray diffraction tensile testing revealed differences in the load partitioning among different Crystal directions. Importantly, the elastic anisotropy expressed by the magnitude of the diffraction elastic constants showed a dependency on the microstructures. KW - Electron microscopy KW - X-ray analysis KW - Inconel 718 KW - Additive Manufacturing KW - Mechanical behavior KW - Diffraction elastic constants PY - 2021 DO - https://doi.org/10.1016/j.msea.2020.140555 VL - 805 SP - 40555 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-52142 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schoder, S. A1 - Schröder, H. V. A1 - Cera, L. A1 - Puttreddy, R. A1 - Güttler, Arne A1 - Resch-Genger, Ute A1 - Rissanen, K. A1 - Schalley, C. A. T1 - Strong Emission Enhancement in pH-Responsive 2:2 Cucurbit[8]uril Complexes JF - Chemistry - A European Journal N2 - Organic fluorophores, particularly stimuli-responsive molecules, are very interesting for biological and material sciences applications, but frequently limited by aggregation- and rotation-caused photoluminescence quenching. A series of easily accessible bipyridinium fluorophores, whose emission is quenched by a twisted intramolecular charge-transfer (TICT) mechanism, is reported. Encapsulation in a cucurbit[7]uril host gave a 1:1 complex exhibiting a moderate emission increase due to destabilization of the TICT state inside the apolar cucurbituril cavity. A much stronger fluorescence enhancement is observed in 2:2 complexes with the larger cucurbit[8]uril, which is caused by additional conformational restriction of rotations around the aryl/aryl bonds. Because the cucurbituril complexes are pH switchable, this system represents an efficient supramolecular ON/OFF fluorescence switch. KW - Sensor KW - pH KW - Dye KW - Supramolecular chemistry KW - Synthesis KW - Host-guest interaction KW - Fluorescence KW - Enhancement KW - Curcubituril KW - Macrocyclus KW - Solid state PY - 2019 DO - https://doi.org/10.1002/chem.201806337 SN - 0947-6539 VL - 25 IS - 13 SP - 3257 EP - 3261 PB - WILEY-VCH Verlag GmbH & Co. KGaA CY - Weinheim AN - OPUS4-47599 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Janssen, H. A1 - Bringmann, J.C. A1 - Emonts, B. A1 - Schröder, Volkmar T1 - Safety-related studies on hydrogen production in high-pressure electrolysers JF - International journal of hydrogen energy N2 - At Juelich Research Center the prototype of an alkaline 120-bar electrolyser has been developed and built. Constructive and process-engineering measures must be taken to ensure the safe operation of such facilities. Potential hazards occur due to the high operating pressure in conjunction with the reactivity of the product gases and the electrolyte. First of all, the operating mode and technical features of the Juelich high-pressure electrolyser will be dealt with. Within the framework of a parametric study, the potential for weight reduction of the prototype while observing the rules for pressure vessel design will be shown. The Federal Institute for Materials Research and Testing in Berlin has performed measurements concerning the explosion limits of H2/O2 mixtures at different temperatures and pressures up to 200 bars. At an electrolysis test rig of IWV-3, which can also be operated up to 200 bars, investigations were carried out concerning the gas composition on the H2 and O2 path under different operating conditions. These measurement series were compared to the explosion limits determined and evaluated to derive safety measures required for the operation of high-pressure electrolysers. KW - High-pressure electrolysis KW - Electrolysis KW - Pressure vessel KW - Explosion limits KW - Explosion pressures PY - 2004 DO - https://doi.org/10.1016/j.ijhydene.2003.08.014 SN - 0360-3199 VL - 29 SP - 759 EP - 770 PB - Elsevier CY - Oxford AN - OPUS4-3534 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -