TY - JOUR A1 - Blankenhagel, Paul A1 - Wehrstedt, Klaus-Dieter A1 - Mishra, K. B. A1 - Steinbach, J. T1 - The capability of commercial CFD code to predict organic peroxide fireball characteristics N2 - Fireballs of liquid organic peroxides differ from those of liquid hydrocarbon fuels. Modified equations for predicting the fireball diameter, height, surface emissive power and the duration in dependence of the fuel mass are presented for di-tert-butyl peroxide. They base on 13 steel drum tests with fuel masses from 10 kg to 168 kg. Moreover, computational fluid dynamics simulations are performed using the laminar flamelet approach and a statistically turbulence treatment. Fireballs involving peroxide from 10 kg to 80 kg were simulated and their properties compared to the experimentally developed models. The deviations of each property are partially compensating each other leading to an adequate prediction of thermal safety distances for both, a time-independent and a time-averaged treatment. Simulations prove to be a good tool for predicting thermal radiation hazards of fireball scenarios. KW - Fireball KW - CFD simulation KW - Organic peroxide KW - Fire safety KW - DTBP PY - 2019 DO - https://doi.org/10.1016/j.jhazmat.2018.11.011 SN - 0304-3894 SN - 1873-3336 VL - 365 SP - 386 EP - 394 PB - Elsevier AN - OPUS4-47054 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Mishra, K. B. A1 - Wehrstedt, Klaus-Dieter ED - Singh, A.P. ED - Agarwal, R. A. ED - Agarwal, A. K. ED - Dhar, A. ED - Shuklar, M. K. T1 - Peroxy-fuels: Burning behavior and potential applications in combustion engines N2 - In present chapter, the potential usage of peroxy-fuels (usually known as organic peroxides) either in technically pure or in a blended form in engine combustion processes are explored. Although as additives (in small quantities <5% to conventional fuels, e.g., diesel, gasoline) peroxy-fuels are well known for many years their commercial applications as a main or primary fuel are not investigated in detail as such except a few. Their thermal instability and energy density demand great care during processing, which restricts their commercial exploitation. However, once the issues with safety are resolved they can be much more advantageously employed than conventional fuels. Some of these advantages are significant amount of fuel saving, reduction in amount of inducted air, or even the complete absence of air, i.e., anaerobic combustion, smaller volume of combustion (chamber), oxygenated fuel quality, and low emissions. An idea to develop the components of an engine operating solely on peroxy-fuels is also introduced. The engine concept is based on single and multiple injectors in a cylinder with special material coating to ensure a temperature-controlled processing. KW - Peroxy-fuels KW - Hydrocarbons KW - Blends KW - Engine combustion KW - Engine performance PY - 2018 SN - 978-981-10-7517-9 DO - https://doi.org/10.1007/978-981-10-7518-6_14 SN - 2522-8366 SN - 2522-8374 SP - 343 EP - 357 PB - Springer Nature Singapore AN - OPUS4-45274 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Blankenhagel, Paul A1 - Wehrstedt, Klaus-Dieter A1 - Steinbach, J. A1 - Mishra, K. B. T1 - Thermal radiation assessment of fireballs using infrared camera N2 - The thermal radiation impact of organic peroxide fireballs is experimentally assessed using an infrared camera. Fireballs are generated while liquid peroxide filled steel drums are subjected to gas burner fire at different heating rates. Three large burning clouds are observed with varying flame characteristics. Thermal radiation properties are assessed by infrared images with the presented methods. Despite of the two-dimensional temperature fields, the flames are treated and characterized as three-dimensional objects. Fireball diameters and heights are calculated based on a representing radiating sphere with the same cloud volume. By the use of the solid flame model and assumptions for emissivity and transmissivity, heat fluxes and thermal radiation doses against distance are predicted. Thermal safety distances are presented based on the maximum irradiance and the allowed exposure time. The validation of the maximum and time-dependent radiation fields is achieved through heat flux sensors in varying distances to the fireball. The results prove the use of an infrared camera and a volume based size calculation to fully assess the thermal radiation hazards of fireballs. KW - Fireball KW - Thermal radiation KW - Infrared camera KW - Organic peroxide KW - Safety distances PY - 2018 DO - https://doi.org/10.1016/j.jlp.2018.04.008 SN - 0950-4230 VL - 54 SP - 246 EP - 253 PB - Elsevier AN - OPUS4-45277 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mishra, K. B. A1 - Wehrstedt, Klaus-Dieter A1 - Krebs, Holger T1 - Prediction of overpressure in buried gas pipeline explosions N2 - The explosion and fire incidents with buried gas pipelines are increasing globally e.g. San Bruno (USA, 2010), East Godavari (India, 2014) and Ludwigshafen (Germany, 2014) are only a few to quote. There are a number of parameters involved behind the occurrence of these incidents such as human mistake, intended efforts leading to major or minor leak, explosion due to depressurization, crater formation, spill of gaseous fuel in the nearby regions and pool/jet/crater fires. In continuation to [3] these parameters are investigated for Ludwigshafen incident in the present work. The semi-empirical and advanced CFD (Computational Fluid Dynamics) based models are utilized to assess the damages caused by the explosion overpressures. Recommendations are also provided on minimum safety distance to be considered for such pipelines to avoid/foresee/mitigate similar hazards in future. T2 - 5. Brand- und Explosionsschutztage 2017 CY - Magdeburg, Germany DA - 23.03.2017 KW - Buried gas pipeline KW - Explosion KW - Overpressure KW - CFD-Model KW - Safety distance PY - 2017 SN - 978-3-00-056201-3 DO - https://doi.org/10.978.300/0562013 SP - 1 EP - 8 AN - OPUS4-40193 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Blankenhagel, Paul A1 - Wehrstedt, Klaus-Dieter A1 - Xu, S. A1 - Mishra, K. B. A1 - Steinbach, J. T1 - A new model for organic peroxide fireballs N2 - Organic peroxides are capable to form fireballs with explosive violence. Only fireball models for liquid hydrocarbon fuels are available for the assessment of the thermal radiation properties. Because the development of such fireballs usually differ from those of organic peroxides the properties need to be characterized by modified equations. In this study liquid organic peroxide fireballs from 16 kg to 155 kg substance masses are characterized and compared to selected existing correlations. Flame characteristics and irradiances are measured with infrared cameras and heat flux sensors. All fireballs are consequences of simulated worst case scenarios where filled steel drums are engulfed by fire with varying heat impact. The differences of the given semi-empirical equations and the presented experimental work are explained. A new model is proposed for organic peroxide fireballs by modifying the constants of the known equations. The thermal radiation impact and safety distances are calculated and compared. KW - Organic peroxide KW - Fireball KW - Thermal radiation KW - Safety distances PY - 2017 DO - https://doi.org/10.1016/j.jlp.2017.10.002 SN - 0950-4230 VL - 50 IS - Part A SP - 237 EP - 242 PB - Elsevier Science AN - OPUS4-43069 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Blankenhagel, Paul A1 - Wehrstedt, Klaus-Dieter A1 - Mishra, K. B. A1 - Steinbach, J. T1 - Prediction of organic peroxide fireball characteristics using CFD simulation N2 - Single and multiple fireballs of di-tert-butyl peroxide are numerically investigated using ANSYS CFX. Calculations contain varying inlet conditions, scale-adaptive shear stress turbulence modeling and one-step combustion reaction on a three-dimensional hexahedral mesh. Time-resolved flame temperatures, sizes and thermal radiation are compared to experimental results. There, fireballs were generated by fire engulfment of steel drums containing 200 l substance. After a vigorous burning, the remaining peroxide forms single and multiple fireballs involving 10 % to 20 % of the initial amount. The comparison of all simulations and two selected experiments show the special numerical treatment required for organic peroxides. Finally, the numerical predictions of irradiance in 30 m distance to the fire show a good agreement for both experiments. This proves the use of CFD as an appropriate method for thermal hazard assessment and the prediction of safety distances for organic peroxide fireballs. T2 - 8th European Combustion Meeting 2017 CY - Dubrovnik, Croatia DA - 18.04.2017 KW - Organic peroxide KW - DTBP KW - Fireball KW - Steel drum KW - Simulation PY - 2017 SN - 978-953-59504-1-7 AN - OPUS4-39992 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Blankenhagel, Paul A1 - Wehrstedt, Klaus-Dieter A1 - Mishra, K. B. A1 - Steinbach, J. T1 - Fireballs as a possible hazard scenario of organic peroxides in steel drums N2 - To simulate a full fire engulfment during transportation or storage a closed removable head steel drum filled with 200 l Di-tert-butyl peroxide (DTBP) is subjected to a wood fire. Due to the enormous heat flux and the exothermic self-decomposition large flames arise and finally multiple fireballs occur. The fireballs consume up to 20 % of the total mass (20 % equals to 31 kg). They are characterized by high surface emissive power and large flames associated with high thermal radiation causing spontaneous ignition of objects in the surrounding. The measured sizes of the DTBP fireballs are smaller compared to the results of the general equations for hydrocarbon fireballs. Because these equations are recommended by the Health and Safety Executive (UK) to be applicable for organic peroxides explicit comparisons of DTBP with LPG, diesel and gasoline concerning the characteristics of fireballs are carried out. Also the burning time is compared and confirms a faster combustion of the peroxide. Moreover, the development of size and emissive power for DTBP and diesel fireballs are compared in a normalized graph. The results provide the assumption that new empirical models are required to be developed for hazard assessment of organic peroxide fireballs. T2 - 5. Brand- und Explosionsschutztage 2017 CY - Magdeburg, Germany DA - 23.03.2017 KW - Organic peroxide KW - DTBP KW - Fireball KW - Steel drum KW - Simulation PY - 2017 SN - 978-3-00-056201-3 DO - https://doi.org/10.978.300/0562013 VL - 2017 SP - 1 EP - 9 PB - Otto-von-Guericke-Universität CY - Magdeburg AN - OPUS4-39994 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Blankenhagel, Paul A1 - Mishra, K. B. A1 - Wehrstedt, Klaus-Dieter A1 - Steinbach, J. T1 - Thermal radiation impact of DTBP fireballs N2 - The burning behaviour and thermal radiation of pool fires of organic peroxides (OP) have been studied by several authors in the past. It was shown that mass burning rates, flame temperatures and thus the Surface Emissive Power (SEP) of OP exceed to that of hydrocarbons considerably. These facts lead to further investigations of even dangerous worst case scenarios i.e. related to storage and transportation. A metal drum containing 200 l of DTBP (Di-tert-butyl peroxide) is investigated under a surrounding wood fire. Due to a higher heat flux to the substance, the mass burning rate reaches multiples of an equivalent pool fire and results in several fireballs. The analyses of thermographic camera images and radiometer measurements show higher flame lengths, higher temperatures and thereforeincreased thermal radiation compared to OP pool fires. The resulting greater safety distances for a DTBP fireball event are discussed. T2 - New Trends in Research of Energetic Materials (NTREM) CY - Pardubice, Czech Republic DA - 20.04.2016 KW - organic peroxide KW - pool fire KW - fireball KW - thermal radiation KW - safety distance PY - 2016 SN - 978-80-7395-976-0 SP - 410 EP - 418 PB - Elsevier AN - OPUS4-35858 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Knechtel, Sophie A1 - Schmidt, Simon A1 - Mishra, K. B. A1 - Wehrstedt, Klaus-Dieter T1 - Modellierung der Hauptbrandszenarien von flüssigem Wasserstoff (LH2) mittels CFD N2 - Die sichere Lagerung und der Transport von Flüssigwasserstoff (LH2) verlangen nach verlässlichen Abschätzungen möglicher Risiken durch Feuer oder Explosion. Aufgrund des breiten Explosionsbereichs (4 Vol.-% - 74 Vol.-%) reagiert Wasserstoff sehr schnell und produziert hohe Flammentemperaturen. Da Wasserstoffflammen ruß- bzw. farblos sind, ist Wärmestrahlung im Fernfeld kein Risikofaktor. Allerdings stellen die hohe lokale Wärmestrahlung und die nicht sichtbaren Flammen eine Gefahr für Menschen und Infrastruktur in der Nähe dar. Es ist daher notwendig die Gefahren von LH2-Feuern sorgfältig zu bewerten. Einerseits sind experimentelle Untersuchungen verschiedener Szenarien teuer, andererseits können sie teilweise auch praktisch nicht durchführbar sein. Numerische Simulationen dieser Szenarien können ein Ausweg aus diesem Problem sein. In der vorliegenden Arbeit wird ein solcher Ansatz genutzt, um große Brandszenarien mit LH2 mittels CFD (Computational Fluid Dynamics) zu modellieren und so die notwendigen Sicherheitsabstände abzuschätzen. Der Fokus liegt dabei auf der Simulation von Jet- und Pool-Feuerszenarien mit einem kommerziellen CFD-Code (Ansys CFX). Die benötigten geometrischen Modelle werden für Jet- und Pool-Feuer erstellt und mit den nötigen Randbedingungen implementiert. Wichtige Submodelle für chemische Reaktionen (Einschritt- und detaillierte Modelle), Verbrennung (Eddy-Dissipation- und Flamelet-Modell) und Strahlung (Discrete-Transfer-Modell) werden genutzt. Die maximal simulierten Flammentemperaturen liegen bei ~2100 K für Jet-Feuer und ~2300 K für Pool-Feuer. Um Aussagen zu thermischen Sicherheitsabständen zu treffen, wurden die Spezifischen Ausstrahlungen (SEP) ermittelt und anschließend entsprechende Positionsfaktoren gewählt, um verlässliche Sicherheitsabstände zu berechnen. Je nach Bedarf können CFD-Modelle sowohl für qualitative als auch für quantitative Risikobewertungen von LH2-Großbränden genutzt werden. T2 - 12. Fachtagung Anlagen-, Arbeits- und Umweltsicherheit CY - Köthen, Germany DA - 05.11.2015 KW - Flüssigwasserstoff KW - Großbrand KW - Poolfeuer KW - Jet-Feuer KW - CFD KW - Sicherheitsabstand PY - 2015 SN - 978-3-86011-091-1 SP - Paper P-11, 1 EP - 8 AN - OPUS4-34827 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -