TY - JOUR A1 - Hahn, S.-K. A1 - Rost, M. A1 - Kusche, Christian A1 - Knaust, Christian A1 - Krause, U. T1 - Dokumentation der Entwicklung des m-Faktors und neuer Aspekt der Verbrennungseffizienz T1 - Structural fire protection in industrial buildings - development of the m-factor and new aspect of the combustion efficiency N2 - Vor dem Hintergrund der Zurückziehung der DIN 18230 Teil 2 zur Bestimmung des m-Faktors von Materialien für die Brandlastbewertung im Industriebau müssen neue Wege gefunden werden, wie das Abbrandverhalten alternativ quantifiziert werden kann. Der Beitrag fasst die Entstehung und die Entwicklung der Bestimmungsweise von Abbrandfaktoren zusammen und gibt Ausblick auf eine neue Möglichkeit zur Bewertung von Brandlasten, die Verbrennungseffizienz. KW - Abbrandfaktor KW - DIN 18230 KW - Indrustriebau KW - Brandschutz im Brandlast KW - Verbrennungseffizienz PY - 2017 DO - https://doi.org/10.1002/bate.201700020 SN - 0932-8351 SN - 1437-0999 VL - 94 IS - 6 SP - 337 EP - 343 PB - Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG CY - Berlin AN - OPUS4-40962 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Palis, Stephan A1 - Sträubig, Felix A1 - Voigt, Sascha A1 - Knaust, Christian T1 - Experimental investigation of the impact of water mist on high-speed non-premixed horizontal methane jet fires N2 - In this paper, the influence of a fixed water mist firefighting system on a high-speed non-premixed horizontal methane jet fire is investigated with focus on its effect on temperatures and heat load of the jet fire and on ist surroundings. Six tests are performed in which gas is released out of an orifice with a diameter of 1 mm and a release pressure of up to 186 bar. In addition to temperature and radiation measurements, the release pressure, gas mass flow rate and exhaust gas concentrations are detected to determine the heat release. Video and IRanalysis are used to evaluate the interactions between jet fire and water mist. The experiments show, that water mist reduces the temperatures inside the jet fire flow field and its radiative heat flux. It can lower the Risk of ignition of adjacent surfaces and materials, as temperatures fall below autoignition temperatures of common materials like plastics. Although water mist does not extinguish the fire, it has an impact on the energy release by reducing combustion efficiency due to heat exchange with the water mist and oxygen displacement. KW - Fixed firefighting system KW - Jet fire KW - Water mist KW - Fire test KW - Methane KW - Supersonic flow PY - 2020 DO - https://doi.org/10.1016/j.firesaf.2020.103005 VL - 114 SP - 103005 PB - Elsevier Ltd. AN - OPUS4-50963 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Voigt, Sascha A1 - Sträubig, Felix A1 - Palis, Stephan A1 - Kwade, A. A1 - Knaust, Christian T1 - CFD-analysis of Sensible Enthalpy Rise Approach to determine the heat release rate of electric-vehicle-scale lithium-ion batteries N2 - This paper analyses the suitability of the Sensible Enthalpy Rise Approach for measuring the heat release rate of electric-vehicle-scale lithium-ion batteries. An apparatus is designed that meets the conditions of an electric-vehicle-scale lithium-ion battery fire by using cement board as wall material. Modifications of the Sensible Enthalpy Rise Methodology are presented due to the high emissivity and inhomogeneous temperature distribution of the apparatus wall material: a power 4 approach for the heat flow from the walls to the ambient air and an alternative determination methodology for the wall temperature. A one factor at a time parameter study is performed with Computational Fluid Dynamics simulations, investigating a new calibration method based on a fit approach compared to common methods, the wall temperature determination, the approach for the ambient heat flow, the calibration power and the volume flow at the outlet. The simulations show, that suitable estimations of the heat release rate are obtained by using the modifications for wall temperature determination and the power 4 approach for the ambient heat flow. The three calibration methods provide suitable constants, if the calibration power in the same order of magnitude as the mean of the heat release rate profile of the test object. KW - Lithium-ion batteries KW - Heat Release Rate KW - Calorimetry KW - Sensible Enthalpy Rise Approach KW - Computational Fluid Dynamics PY - 2020 DO - https://doi.org/10.1016/j.firesaf.2020.102989 VL - 114 SP - 1 EP - 14 PB - Elsevier Ltd. AN - OPUS4-50964 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Voigt, Sascha A1 - Sträubig, Felix A1 - Palis, Stephan A1 - Kwade, A. A1 - Knaust, Christian T1 - Experimental comparison of Oxygen Consumption Calorimetry and Sensible Enthalpy Rise Approach for determining the heat release rate of large-scale lithium-ion battery fires N2 - From a fire safety point of view, the burning behavior of lithium-ion batteries is of high interest. The heat release rate (HRR) is the most important fire parameter to analyze the fire hazards of burning objects, so that an accurate determination of it is crucial. In this paper, two different measurement techniques, the Oxygen Consumption Calorimetry (OCC) and the Sensible Enthalpy Rise Approach (SERA) are simultaneously performed in the same calorimeter to measure the HRR of two different types of lithium-ion batteries. HRR values as well as total energies determined by SERA are higher than measured with OCC: The total energy released is about 10–12 times (SERA) and 6–9.5 times (OCC) the electrical stored energy for both battery types, whereas the timescales of the release differ strongly between the types, resulting in maximum HRRs of 3.4 MW (SERA) and 1.5 MW (OCC) for one module of type A and 0.8 MW (SERA) and 0.6 (OCC) of type B respectively. Furthermore, a sensitive dependency of the HRR measurement with SERA on the position of the wall temperature measurement is observed. KW - Fire tests KW - Lithium-ion-batteries KW - Heat release rate KW - Calorimetry KW - Sensible enthalpy rise approach KW - Oxygen consumption calorimetry PY - 2021 DO - https://doi.org/10.1016/j.firesaf.2021.103447 SN - 0379-7112 IS - 126 PB - Elsevier Ltd. AN - OPUS4-53441 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Voigt, Sascha A1 - Sträubig, Felix A1 - Kwade, A. A1 - Zehfuß, J. A1 - Knaust, Christian T1 - An empirical model for lithium-ion battery fires for CFD applications N2 - Lithium-ion batteries are a key technology to achieve the goals of limiting climate change due to the important role as traction technology for Electric Vehicles and in stationary energy storage systems. Over(dis) charge, mechanical damage due to accidents or thermal abuse such as fires can initiate an accelerated self-heating process of the batteries, called thermal runaway. A thermal runaway can propagate from cell to cell within a larger assembly of cells such as modules or battery packs and can cause rapid heat and toxic gas emissions. The resulting battery fire can spread to adjacent facilities, e.g. other cars in underground car parks or to a whole building in case of a large stationary energy storage. For proof of fire protection requirements or to design suitable fire protection systems, Computational Fluid Dynamic (CFD) simulations are getting more and more important. The aim of CFD fire simulations is to predict the global hazards of a fire to its surroundings, that is mainly characterized by the release of heat and smoke and its spread in the fire environment. There are many numerical investigations of lithium-ion batteries in the literature. One class of models is used to simulate the charge and discharge process of lithium-ion batteries and to predict the temperature or voltage evolution inside the battery. On the other hand, there are models describing batteries under abuse conditions to predict the consequences of a thermal runaway event to the local environment, like the temperatures inside a battery or at the battery surface. Henriksen et al. use a generic battery gas mixture to simulate an explosion of vented gases from a Lithium Iron Phosphate battery and compare experimental results for the explosion pressure and the position of the flame front to the outcomes of a simulation with Xifoam. Larsson et al. used a combination of CFD simulations with FDS and thermal model with COMSOL to predict the temperature development of neighboring cells in a thermal runaway propagation. Truchot et al. use a design Heat Release Rate (HRR) curve for a battery based on experimental measurements to build up an overall HRR curve for a truck loaded with 100 lithium-ion batteries. This summed up HRR and corresponding smoke production curve is then used as an input for a simulation of a truck fire in a tunnel with Fire Dynamics Simulator (FDS). The pre-definition of the HRR curve is a frequently used method in fire engineering. It has the disadvantage, that the heat release cannot be influenced by physical processes, such as changed ventilation conditions or extinguishing measures. In this paper, a model is presented that determines the release of heat and gases based on the thermal runaway mechanisms of the battery, which can be used in CFD fire simulations with focus on prediction of fire hazards to nearby environment. KW - Lithium-ion battery KW - Battery fires KW - Computational Fluid Dynamic (CFD) KW - Empirical model PY - 2023 DO - https://doi.org/10.1016/j.firesaf.2022.103725 SN - 0379-7112 VL - 135 IS - 135 SP - 1 EP - 12 PB - Elsevier Ltd. AN - OPUS4-57347 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Chaves Spoglianti de Souza, Roberto A1 - Andreini, M. A1 - La Mendola, S. A1 - Zehfuß, J. A1 - Knaust, Christian T1 - Probabilistic thermo-mechanical finite element analysis for the fire resistance of reinforced concrete structures N2 - This paper presents a probabilistic methodology based on the thermo-mechanical finite elements analysis to investigate the impact of the variability of the thermal properties of the concrete in the fire safety of structures. This is meant to evaluate if characteristic values or safety factors for the conductivity and specific heat are required during the semi-probabilistic structural fire safety assessment. To illustrate the use of the proposed methodology, this work includes a case-study with a tunnel lining which considers the uncertainties related to the thermal and mechanical properties of the concrete, the soil load, and the temperatures described by the standard temperature-time curve. Two failure criteria are considered: one was the maximum temperature of 300 °C at the reinforcement and the other based on the temperature-dependent strength as provided in the Eurocode EN 1992-1-2. Several finite element analyses are performed. The design of experiments is executed by a Correlation Latin Hypercube Sampling. The calculated probability of failure has different values depending on the adopted failure criteria. A sensitivity analysis using the Spearman's rank correlation coefficient was carried out and demonstrates that the uncertainty related to the specific heat has the greatest impact on the results. KW - Fire Safety KW - Concrete KW - Probabilistic KW - Finite Elements PY - 2018 DO - https://doi.org/10.1016/j.firesaf.2018.12.005 SN - 0379-7112 VL - 104 SP - 22 EP - 33 PB - Elsevier AN - OPUS4-47422 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nandish, Ranjith A1 - Knaust, Christian A1 - Zehfuß, Jochen T1 - Numerical Investigations of a Large Fire Exposure Crib Test—Presenting Different Pyrolysis Modelling Methodologies and Numerical Results N2 - ABSTRACTThe need for numerical‐based approaches to investigate the fire behaviour in buildings with combustible components is growing due to the increasing use of timber by the construction industry to meet the ‘Climate Action Plan 2050’. This requires consideration of the complex kinetic processes that take place during the burning of the wood in the numerical models. This is accomplished by using computational fluid dynamics (CFD) to numerically model the material pyrolysis and combustion processes. This article presents three different approaches for simulating the behaviour of a wood crib fire using the fire dynamics simulator (FDS). These approaches are based on either prescribing the burning rate of the wood directly from the physical experiments or using the kinetic parameters to govern the underlying processes, such as pyrolysis. Wooden crib fire experiments carried out by the RISE Research Institute in Sweden inside the combustion chamber that were used to validate all the methods. The numerical results from the method, that utilised the experimentally determined burning rate, were in good agreement with the experimental results, with a maximum deviation of 6% in the case of HRR. On the other hand, the model that needs kinetic parameters as its input has shown maximum discrepancies of 12% and 33% compared to experimental results. These methods are sensitive to the input parameters and the extent of dependency needs further investigation. KW - Pyrolysis KW - Wood combustion KW - Wood fire loads KW - Wooden buildings PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-626567 DO - https://doi.org/10.1002/fam.3287 SN - 1099-1018 VL - 49 IS - 4 SP - 371 EP - 387 PB - John Wiley & Sons Ltd. AN - OPUS4-62656 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Knaust, Christian T1 - Modellierung von Tunnelbränden - Kopplung von Fluid und Struktur T1 - Modeling tunnel fires – Coupling of fluid and structure N2 - Heute verfügbare Technik ermöglicht es, die Wärmetransportmechanismen im Brand, an der Bauteiloberfläche und im Bauteil mittels CFD zu koppeln. Die Kopplung von Fluid und Struktur wurde am Beispiel eines 100-MW-Tunnelbrands mit CFD (Computational Fluid Dynamics) untersucht. Die instationären Berechnungen wurden mit dem CFD-Programm ANSYS Fluent durchgeführt. Der infolge eines Lkw-Unfalls verursachte n-Heptan-(C7H16)-Brand wurde mit dem Eddy-Dissipation-Verbrennungsmodell modelliert. Das Fluid- und Solid-Gebiet wurden durch ein ‚Interface‘ gekoppelt. Die instationäre Wärmeleitung des Bauteils mit einer Höhe von 0,4 m wurde mit der dreidimensionalen Fourier´schen Wärmeleitungsgleichung modelliert und das instationäre thermische Verhalten des quarzhaltigen Betonbauteils analysiert. Temperaturabhängige Stoffkennwerte wurden berücksichtigt. N2 - The current technology allows the coupling of the temperaturedependent heat transfer mechanisms in case of fire within the structural components and at their surface by means of computational fluid dynamics (CFD). In this paper the thermal coupling of a fluid and a solid region in case of a 100 MW tunnel fire caused by a truck was carried out with CFD. The transient fire simulations were performed with the CFD program ANSYS Fluent. The fire was modeled by the combustion of n-heptane (C7H16) using the eddy dissipation model. The fluid and the solid region were coupled by an interface. The unsteady heat conduction for the 0.4 m thick concrete structure is modeled by using the Fourier heat transfer equation. The transient thermal behavior of quartz containing concrete component was analyzed. Temperature-dependent material properties were considered. KW - Wärmeleitung KW - Berechnungen analytische und empirische KW - ANSYS Fluent KW - Radiation KW - Computational fluid dynamics KW - Temperature dependent properties KW - Analytical and empirical calculations KW - Wärmeübertragung KW - Strahlung KW - Temperaturabhängige KW - Heat transfer KW - Conduction PY - 2016 DO - https://doi.org/10.1002/bate.201600045 SN - 0932-8351 SN - 1437-0999 VL - 93 IS - 8 SP - 543 EP - 554 PB - Ernst & Sohn CY - Berlin AN - OPUS4-37211 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lerena, P. A1 - Auerkari, Pertti A1 - Knaust, Christian A1 - Vela-Wallenschus, Iris A1 - Krause, U. T1 - Approaches towards a generic methodology for storage of hazardous energy carriers and waste products N2 - Energy carriers – either conventional or 'new' ones – have to be provided in large amounts to meet the requirements of permanent availability and reliable supply of electricity. Depending on their state of aggregation, energy carriers are either stored in large masses (if solid or liquid) or at elevated pressures (if gaseous). Both impose the hazard of large-scale fire, in the latter case additionally the danger of explosion or unintended release. Very similar hazards occur for wastes. Solid wastes are present in large masses and only a small part is recycled. Most of the solid wastes are used in energy conversion. The main gaseous waste is CO2. During capturing also the hazard of unintended release exists. In this article, existing approaches for safe storage and fire prevention are discussed and a generic methodology is outlined. This methodology consists of the following steps: • gaining knowledge about the behaviour of the material stored (reactivity, thermal stability, etc.), • assessing the environmental conditions for the storage site (neighbourhood, safety distances, etc.), • assessment of prospective consequences of an incident and • development of individual loss prevention conceptions. All steps require both experimental testing and theoretical considerations about accident scenarios as integral parts of the methodology. KW - Storage KW - Hazardous materials KW - Energy carriers PY - 2013 DO - https://doi.org/10.1080/13669877.2012.729524 SN - 1366-9877 SN - 1466-4461 N1 - Geburtsname von Vela-Wallenschus, Iris: Vela, I. - Birth name of Vela-Wallenschus, Iris: Vela, I. VL - 16 IS - 3-4 SP - 433 EP - 445 PB - Taylor & Francis CY - London [u.a.] AN - OPUS4-26882 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kaudelka, Sven A1 - Knaust, Christian A1 - Krause, U. T1 - Ansätze zur numerischen Berechnung von Brandeinwirkungen auf Bauteile N2 - Bei der Erstellung von brandschutztechnischen Nachweisen für Industriebauten werden häufig Ingenieurmethoden des Brandschutzes genutzt. Dazu zählen die Modellierung und Berechnung von Brandszenarien mittels numerischer Strömungsmechanik (computational fluid dynamics, CFD). In dieser Arbeit wurde ein auf numerischer Strömungs- und Strukturmechanik basierendes Verfahren zur brandschutztechnischen Bemessung von Bauteilen am Beispiel einer Industriehalle angewendet. Instationäre Temperaturverläufe aus der Heißgasschicht dienten dabei als Eingangswerte für die Bauteilberechnung. Aus den Ergebnissen wurde die äquivalente Branddauer berechnet, mit der die rechnerisch erforderlichen Feuerwiderstandsdauern der Bauteile bestimmt werden konnte. KW - Äquivalente Branddauer KW - Brandschutz im Industriebau KW - Feuerwiderstandsdauer KW - Numerische Strömungsmechanik KW - Numerische Strukturmechanik PY - 2016 DO - https://doi.org/10.1002/cite.201500174 SN - 1522-2640 SN - 0009-286X VL - 88 IS - 8 SP - 1157 EP - 1168 PB - Wiley CY - Weinheim AN - OPUS4-38179 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -