TY - JOUR A1 - Berger, Anka A1 - Krause, Ulrich T1 - Investigations on the self-ignition of deposits containing combustibles JF - Fire and materials N2 - Self-ignition of deposited combustibles is a possible reason for excessive fires occurring on deposits for recycling materials or on waste dumps. Two series of experiments were performed to assess the hazard of self-ignition: hot storage tests with different homogeneous mixtures of combustible material and inert material and tests with pockets of combustible material embedded in inert matter. In the first test series considerable exothermicity (ΔT>60K) was observed for mass fractions of combustible material as low as 2.5%. In the second series it could be shown that the heat transfer from a pocket of burning material through the inert matter can ignite a second pocket of combustible matter. Based on the experimental data, numerical simulations were performed to predict self-ignition on real-scale waste deposits. For a deposit of specific size and shape, the influence of the ambient temperature on the occurrence of self-ignition has been investigated. KW - Self-ignition KW - Hot storage tests KW - Cellulose KW - Municipal solid waste KW - Numerical simulations PY - 2008 DO - https://doi.org/10.1002/fam.966 SN - 0308-0501 SN - 1099-1018 VL - 32 IS - 4 SP - 231 EP - 248 PB - Heyden CY - London AN - OPUS4-17577 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Everard, C.D. A1 - Schmidt, Martin A1 - McDonnell, K.P. A1 - Finnan, J. T1 - Heating processes during storage of Miscanthus chip piles and numerical simulations to predict self-ignition JF - Journal of loss prevention in the process industries N2 - Miscanthus x Giganteus (Miscanthus) energy crop was examined at laboratory scale to assess its self-heating and self-ignition risks during storage. Chipped Miscanthus (18 mm) from February and March harvests, in 2012, were assessed as well as ground Miscanthus (3 mm) from the March harvest. February and March crops had moisture contents of 41.6 and 20.2%, respectively. Self-ignition temperatures were independent of moisture although moisture did affect the time from the beginning of storage until storage temperature was reached. Ground Miscanthus had lower self-ignition temperatures than chipped Miscanthus. Isothermal respirometric tests carried out showed increase risk of self-heating in the February crop compared to the March crop due to increased microbial activity. Numerical simulations were used to determine critical enhanced start temperatures, e.g. caused by microbial decomposition, of the stored Miscanthus. Safe storage conditions have been derived from the investigations. The numerical simulations demonstrated that self-ignition was possible in Miscanthus chip piles with a height greater than 6 m if there was significant heat release from microbiological activity. Reliable assessment of self-heating and self-ignition risks in large scale Miscanthus energy crop clamps or piles are required to prevent losses due to decomposition and fire damage. KW - Miscanthus x Giganteus KW - Hot storage test KW - Respirometric rates KW - Self-heating KW - Self-ignition KW - Numerical simulations KW - Biomass storage PY - 2014 DO - https://doi.org/10.1016/j.jlp.2014.06.003 SN - 0950-4230 SN - 1873-3352 VL - 30 SP - 188 EP - 196 PB - Butterworth CY - Guildford, Surrey AN - OPUS4-31149 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krüger, Simone A1 - Hofmann-Böllinghaus, Anja A1 - Berger, Anka A1 - Gude, Nicolas T1 - Investigation of smoke gases and temperatures during car fire – large-scale and small-scale tests and numerical investigations JF - Fire and Materials N2 - The hazards for passengers during vehicle fires result from the increasing temperature and the emitted smoke gases. A fire was set on a car to investigate the development of temperature and of gaseous fire products in the passenger compartment. The study was based on a full-scale test with a reconstructed scene of a serious car fire. The aim of this work was to identify the conditions for self-rescuing of passengers during a car fire. A dummy, equipped with several thermocouples, was placed on the driver’s seat. Also, the smoke gases were continuously collected through a removable probe sensor corresponding to the nose of the dummy in the passenger compartment and analyzed using Fourier transform infrared spectroscopy. Additionally, several car components were investigated in the smoke density chamber (smoke emission and smoke gas composition). It was found that the toxic gases already reached hazardous levels by 5 min, while the temperatures at the dummy were at that time less than 80 °C. The toxicity of smoke gases was assessed using the fractional effective dose concept. The various experimentally parameters (temperature and smoke gas composition) were implemented into numerical simulations with fire dynamics simulator. Both the experimental data and the numerical simulations are presented and discussed. KW - Smoke gases KW - FTIR spectroscopy KW - Car fire KW - Temperatures KW - FED KW - Numerical simulations PY - 2016 DO - https://doi.org/10.1002/fam.2342 SN - 1099-1018 VL - 40 IS - 6 SP - 785 EP - 799 PB - Wiley CY - Sussex, UK AN - OPUS4-37518 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lohrer, Christian A1 - Krause, Ulrich A1 - Steinbach, J. T1 - Self-Ignition of Combustible Bulk Materials under Various Ambient Conditions JF - Process safety and environmental protection T2 - HAZARDS XVIII "Process safety - sharing best practice" CY - Manchester, England, UK DA - 2004-11-22 KW - Selbstentzündung KW - Sauerstoffanteil KW - Wasser KW - Modellierung KW - Self ignition KW - Wetting KW - Condensation KW - Evaporation KW - Numerical simulations PY - 2005 SN - 0957-5820 SN - 1744-3598 VL - 83 IS - B2 SP - 145 EP - 150 PB - Elsevier CY - Amsterdam AN - OPUS4-7498 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rethmeier, Michael A1 - Gumenyuk, Andrey A1 - Bachmann, Marcel T1 - High-power laser beam welding for thick section steels – new perspectives using electromagnetic systems JF - Science and Technology of Welding and Joining N2 - In recent years, it was shown that the introduction of additional oscillating and permanent magnetic fields to laser beam and laser-arc hybrid welding can bring several beneficial effects. Examples are a contactless weld pool support for metals of high thickness suffering from severe drop-out when being welded conventionally or an enhanced stirring to improve the mixing of added filler material in the depth of the weld pool to guarantee homogeneous resulting mechanical properties of the weld. The latest research results show the applicability to various metal types over a wide range of thicknesses and welding conditions. The observations made were demonstrated in numerous experimental studies and a deep understanding of the interaction of the underlying physical mechanisms was extracted from numerical calculations. KW - Laser beam welding KW - Numerical simulations KW - Electromagnetic support PY - 2021 DO - https://doi.org/10.1080/13621718.2021.1999763 VL - 27 IS - 1 SP - 43 EP - 51 PB - Taylor & Francis Group AN - OPUS4-53970 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ruedrich, J. A1 - Rieffel, Y. A1 - Pirskawetz, Stephan A1 - Alpermann, H. A1 - Joksch, U. A1 - Gengnagel, C. A1 - Weise, Frank A1 - Plagge, R. A1 - Zhao, J. A1 - Siegesmund, S. T1 - Development and assessment of protective winter covers for marble statuaries of the Schlossbrücke, Berlin (Germany) JF - Environmental earth sciences N2 - The present study documents the results of an inter-disciplinary model project that was planned with the aim of developing an innovative winter covering system for marble statuaries located on the Schlossbru¨cke (Berlin). Such a system would need to fulfil the various requirements for structural stability, aesthetics, climate and practical use. This applied research represents the first complex scientific study of the sustainability of a winter covering system. The study is characterised by the use of complex scientific instruments such as special laboratory analysis and numerical simulation tools. The interaction between the environment and the artefacts in connection with the innovative winter covering structures were studied by extensive climatic monitoring. KW - Marble sculptures KW - Marble weathering KW - Winter cover KW - Climate data KW - Numerical simulations PY - 2011 DO - https://doi.org/10.1007/s12665-010-0765-2 SN - 1866-6280 SN - 1866-6299 VL - 63 IS - 7-8 SP - 1823 EP - 1848 PB - Springer CY - Berlin; Heidelberg AN - OPUS4-22363 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Steensma, M. A1 - Schuurman, P. A1 - Malow, Marcus A1 - Krause, Ulrich A1 - Wehrstedt, Klaus-Dieter T1 - Evaluation of the validity of the UN SADT H.4 test for solid organic peroxides and self-reactive substances JF - Journal of hazardous materials N2 - Many self-accelerating decomposition temperatures (SADTs) of solid organic peroxides and self-reactive substances have been determined with the UN test method H.4, which is a scaled down test in a small Dewar vessel. For solid organic peroxides and solid self-reactive substances Fierz has questioned this procedure in a recent paper. Fierz concluded that the Dewar test results should not be extrapolated to beyond 8 l packages, owing to the thermal insulation value of solids. On the other hand, long term experience with the test, with a great variety of solid organic peroxides and self-reactive substances show about equal critical temperatures in the small Dewar vessel and on 50 kg scale. In the present work, we first checked, by numerical simulations, the Dewar scale versus the larger scale, in a way comparable with Fierz’ method: both scales are simulated by spheres, consisting of a number of annular layers, for the large scale the usual external heat loss term is used but for the small scale the outside heat transfer is strongly limited. The outcome of these simulations, covering a variety of physical parameters, supports the concerns expressed by Fierz. After this, we performed accurate cooling and heating experiments with solid organic peroxide in the usual Dewar vessel, provided with a large set of thermocouples. The results of these experiments showed that the simulation model for the Dewar vessel has to be changed from a spherical analogue to a short cylinder of solid material with heat exchange mainly via its top (Utop 3.5 W/(m2 K), overall heat transfer coefficient) and some heat exchange (Uside 0.29 W/(m2 K)) through its cylindrical and bottom part. With this “modified cylinder” model (being neither an infinitely long cylinder nor a slab) of the Dewar vessel, we found that the UN method H.4 enables an accurate prediction of the SADT, with small deviations of 0 ± 2.5 °C. Further, by performing a truly three-dimensional (3D) finite element calculation in FEMLAB, the new heat characteristics of the Dewar vessel as well as a 50 kg package of dilauroyl peroxide, a solid organic peroxide, were checked. The outcome was compared with the critical ambient temperatures known for various package sizes, which agreed well. KW - SADT of solids KW - Transport regulations KW - UN H.4 test (HAST) KW - Numerical simulations KW - Scale-up procedure PY - 2005 DO - https://doi.org/10.1016/j.jhazmat.2004.09.028 SN - 0304-3894 VL - 117 IS - 2-3 SP - 89 EP - 102 PB - Elsevier CY - Amsterdam AN - OPUS4-5604 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -