Filtern
Erscheinungsjahr
Dokumenttyp
- Vortrag (26)
- Beitrag zu einem Tagungsband (25)
- Zeitschriftenartikel (13)
- Posterpräsentation (11)
- Beitrag zu einem Sammelband (2)
- Dissertation (1)
Schlagworte
- Pool fire (11)
- CFD simulation (9)
- CFD (7)
- Peroxy-fuels (7)
- Mass burning rate (6)
- Organic peroxides (6)
- TBPB (6)
- TBPEH (5)
- Overpressure (4)
- Safety distance (4)
- DTBP (3)
- Explosion (3)
- Hydrocarbons (3)
- Industrial fires (3)
- Organic peroxide (3)
- Safety distances (3)
- Safety measures (3)
- Storage units (3)
- Combustion (2)
- DSC (2)
- Di-tert-butyl peroxide (DTBP) (2)
- Emission (2)
- Energetic materials (2)
- Experimental study (2)
- Flammable liquids (2)
- Froude number (2)
- Irradiance (2)
- Organische Peroxide (2)
- Peroxy-fuel (2)
- Pool fires (2)
- Poolfeuer (2)
- Process industries (2)
- SADT (2)
- Surface emissive power (2)
- Thermische Strahlung (2)
- AIBN (1)
- Alcohols (1)
- BLEVE (1)
- Bestrahlungsstärke (1)
- Bhopal disaster (1)
- Blends (1)
- Burner (1)
- Burner concept (1)
- Burning characteristics (1)
- CFD (Computational Fluid Dynamics) (1)
- CFD (Computational fluid dynamics) (1)
- CFD Simulation (1)
- CFD model (1)
- CFD modeling (1)
- CFD simulations (1)
- Combustion chamber (1)
- Decomposition (1)
- Dense cloud (1)
- Dense gas dispersion (1)
- Di-tert-butyl peroxide (1)
- Di-tert-butylperoxid (1)
- Di-tert-butylperoxide (DTBP) (1)
- Diffusion flame (1)
- Dispersion (1)
- Exothermic decomposition reaction (1)
- Explosion and fire (1)
- Feuerbälle (1)
- Fire (1)
- Fire characteristics (1)
- Flame length (1)
- Flame merging (1)
- Flame temperatures (1)
- Flow rate control (1)
- Fuel Froude number (1)
- Hybrid fuel (1)
- Hydrocarbon (1)
- Internal combustion engine (1)
- Isododecan (1)
- JP-4 (1)
- Jet A (1)
- Jet fires (1)
- KW-Poolfeuer (1)
- Kerosene (1)
- Kerosin (1)
- Ketones (1)
- Limiting distances (1)
- Liquefied natural gas (1)
- Massenabbrandrate (1)
- Massenabbrandraten (1)
- Modeling (1)
- Multiple Poolfeuer (1)
- Multiple fires (1)
- Multiple n-heptane pool fire (1)
- Natural gas (1)
- Navier-stokes equations (1)
- Onset-Temperatur (1)
- Oscillatory burning (1)
- Overflow Reynolds number (1)
- Performance (1)
- Peroxid-Poolfeuer (1)
- Peroxide and kerosene pool flames (1)
- Pool flame (1)
- Porous medium (1)
- Radiation (1)
- Reaktionskinetik (1)
- Refinery disaster (1)
- Retinery incident (1)
- Reynolds number (1)
- Self-sustained (1)
- Sicherheitsabstände (1)
- Smoke dispersion (1)
- Species mass fractions (1)
- Spezifische Ausstrahlung (1)
- Spill characteristics (1)
- Spill-over (1)
- TBPB (tert-butyl-peroxy benzoat) (1)
- Temperature (1)
- Temperature measurement (1)
- Thermal safety distances (1)
- Thermische Stabilität (1)
- Three Es (1)
- Turbulent fire (1)
- UN-Test H.1 (1)
- UN-Test H.4 (1)
- Underground pipeline (1)
- Validated CFD simulation (1)
- Vapor cloud (1)
- Vapor cloud explosion (1)
- Vehicle propulsion (1)
- Wechselwirkende Poolfeuer (1)
- n-Heptan (1)
- organic peroxides flame characteristics (1)
- safety distance (1)
Eingeladener Vortrag
- nein (26)
Experimental investigation and CFD simulation of organic peroxide pool fires (TBPB and TBPEH)
(2010)
Time averaged mass burning rate (m˙′′f ), flame length (H), temperature (T ), irradi- ance (E) and surface emissive power (SEP ) of TBPB (tert -butyl peroxybenzoate) and TBPEH (tert-butyl peroxy-2-ethylhexanoate) pool fires are measured for six pool di- ameters (d = 0.059 m, 0.107 m, 0.18 m, 0.5 m, 1 m and 3.4 m) at BAM in house and outside test facility. The measured heats of combustion (–Δhc) of TBPB and TBPEH are 30113 kJ/kg and 34455 kJ/kg and the specific heat capacities at constant pressure (cp) are 1.8 kJ/(kg K) and 2.1 kJ/(kg K) respectively. The measured m˙′′f of TBPB and TBPEH pool fires are in the range of 0.37 kg/(m2 s)≤ m˙ ′′ f ≤ 0.83 kg/(m2 s) and show little dependence on the pool diameter d, and are four to sixty times higher (for d = 1 m) than that of hydrocarbon pool fires. It is shown that the mass burning rates of the investigated organic peroxides can be represented as an exponential function of the self-accelerating decomposition temperature (SADT). Low SADT implies that the organic peroxide pool fires burn at a much higher m˙′′f than hydrocarbon pool fires. Fuel Froude numbers (Frf) of TBPB and TBPEH are 5 to 100 times (depending on d) higher than for hydrocarbon pool fires. Due to higher Frf the H of TBPB and TBPEH (measured with a S-VHS Videocamera) are found to be two times larger (d = 1 m) than corresponding pool fires of hydrocarbons. Heskestads flame length correlation predicts the Hd (d = 3.4 m) of TBPB and TBPEH pool fires much better than Thomas and Fay correlations. The measured time averaged flame temperatures T (d = 3.4 m) for TBPB and TBPEH pool fires are in the range of 1400 K ≤ T ≤ 1500 K and are 200 K to 300 K higher than for JP-4, kerosene and gasoline. The irradiances of the TBPB and TBPEH pool fires measured by radiometers are E (Δy/d = 0.3) = 45 kW/m2 and E = 98 kW/m2 which are two to ten times higher in comparison to the corresponding n-pentane, super gasoline and diesel pool fires. So the thermal safety distances for organic peroxide pool fires are larger by a factor four in comparison to the hydrocarbon pool fires. An infrared thermography system is used for the determination of SEP of TBPB and TBPEH pool fires. The values of surface emissive power for TBPB and TBPEH are SEP (d = 3.4 m) = 196 kW/m2 and SEP = 258 kW/m2 and thus the SEP are by a factor of approximately two higher than for hydrocarbon pool fires. A self-sustained pulsating Hd (’W’-Effect) is found in TBPB pool flames and is further analysed to explain the reason of occurance on the basis of chemical structure of the fuel and discontinuous heat flux back from flame to the liquid pool. CFD simulations of TBPB and TBPEH pool fires at d = 0.18 m, 0.5 m, 1 m, 3.4 m and 8 m are carried out using the Unsteady Reynolds Averaged Navier Stokes (URANS) equa- tions. The three-dimensional geometries have been discritized with unstructured hybrid grids, with the number of cells in the range of 1 million. Depending on the grid resolu- tion and the pool diameter time steps of 0.0001 s ≤ Δt ≤ 0.01 s for the CFD simulations are used. For solving the discritized equations a finite volume based implicit solver AN- SYS CFX has been used. For modelling the combustion, stoichiometric combustion for both peroxides are assumed. The temperature dependence of the reaction rate has been determined by the Arrhenius approach. For modelling the combustion eddy dissipation concept (EDC) model has been used. For turbulence buoyancy modified k- � and SAS (Scale Adaptive Simulation) turbulence models are used. For the thermal radiation and soot mass fraction discrete transfer radiation model and Magnusson soot model have been used. A new method is suggested for the prediction of mass burning rate (m˙′′f ) by CFD simula- tion. Both peroxide pool fires show approximately constant mass burning rate indepen- dent of d whereas m˙′′f of TBPEH are under predicted at the beginning but show relatively good agreement with measurements for large pool diameters (d = 1 m). In case of TBPB the CFD simulation over predicts the mass burning rate m˙′′f of small TBPB pool fires and shows a continuous decrease with d. CFD predicts the flame length H close to the measured data provided that the constants in Thomas equation are modified. The CFD predicted time averaged surface emission flame temperatures of TBPB and TBPEH pool fires (d = 3.4 m, 1437 K and 1542 K) are in good agreement with the measured time averaged flame temperatures. The CFD predicted SEP for TBPB and TBPEH pool fires (d = 3.4 m, 217 kW/m2 and 288 kW/m2) are also in agreement with the measured values. From the CFD predicted irradiance ECFD it is possible to determine the thermal safety distances from large pool fires of hydrocarbons and organic peroxides.
Data and prediction for the mass burning rate of a tert-butyl-peroxy-benzoat (TBPB) pool fire (pool diameter = 3 m) is presented. The mass burning rates of TBPB fires are up to six times higher and less dependent on pool diameter compared to hydrocarbon pool fires caused by an additional heat release rate due to exothermic decomposition reaction in the liquid phase. This heat release rate is calculated using a 1st order reaction kinetic obtained from micro calorimetric measurements. A new model is derived considering the heat release rate due to the decomposition reaction which is shown to be 100 % of the heat release rate radiated to the pool surface. With the presented model, including also physical quantities, especially the limiting fuel concentration for upward flame propagation, it is possible to predict the mass burning rates of large TBPB pool fires. The predicted values are in very good agreement with the experiments.
The diffusive burning characteristics of four peroxy-fuels (usually known as liquid organic peroxides) and one hydrocarbon fuel are experimentally investigated targeting alternative fuels (or as additives to conventional fuels) for the future. Measurements are performed in form of pool fires with pool diameters in the range between 1 cm and 1 m. Mass, momentum and energy transfer studies are carried out by measuring the mass burning rate, flame length, flame temperature and radiation heat transfer across the liquid fuel and gaseous flame. It has been shown that comparatively much less mass of peroxy-fuels and pressure drop (required to maintained the flow) of fuel are required to produce a given heat flux. The momentum delivered by the peroxy-fuel vapours are order of magnitude higher than for hydrocarbons making the visibility of flame to be 4–5 times larger. A heat balance analysis shows that the total heat release rate of a peroxy-fuel fire is contributed equally by convection and radiation. Finally, the three E's (Efficiency, Economy and Emission) are discussed in the context of present experimental results followed by some recommendations concerning safe handling of the proposed fuels.
Industrial fire and explosion hazards due to accidents in fuel storage units have gained a
considerable attention in the recent times. Both the regulatory bodies and scientific communities
are heavily concerned about the proper safety measures to avoid such calamities in future. This
paper aims to bring some essentials related to the hazards arose from the recent fuel storage fire
accident occurred in Buncefield, UK (2005), Puerto Rico, USA (2009) and Sitapura, India (2009).
The potential similarities behind occurrence of these accidents are studied. The applicability of
various methods (models) and also computer simulations to estimate the safety distances
according to the international standards for both explosion and fire hazard are verified. The
overpressures caused by the Vapor Cloud Explosion (VCE) and radiation flux emitted by the fire
are considered for respective explosion and fire hazard estimations. The prime focus is placed
on the regulations laid down by the National Fire Protection Agency of the United States and
the European Norms.
Data and predictions for the mass burning rates of di-tert-butyl peroxide (DTBP) pool fires (0.003 m < pool diameter < 3 m) are presented. The mass burning rates of DTBP fires are up to five times higher and are less dependent on pool diameter compared to hydrocarbon pool fires caused by an additional heat release rate due to exothermic decomposition reaction in the liquid phase. This heat release rate is calculated using a first-order reaction kinetic obtained from microcalorimetric measurements. A new model is derived considering the heat release rate due to the decomposition reaction, which is shown to be 40% of the heat release rate radiated to the pool surface. With the presented model, which also includes physical quantities, especially the limiting fuel concentration for upward flame propagation, it is possible to predict the mass burning rates of large DTBP pool fires. The predicted values are in very good agreement with the experiments.
Es werden Experimente zur Bestimmung der Massenabbrandraten von multiplen Poolfeuern präsentiert. Als Modellsubstanzen dienen n-Heptan und Di-tert-butylperoxid (DTBP). Es werden Versuche im Labormaßstab mit Durchmessern von d = 6 cm und relativen Abständen von 0.08 ≤ D/d ≤ 4 beschrieben und durch Feldversuche mit Pooldurchmessern d = 1.5 m und relativen Abständen zwischen den Pool von 0.17 ≤ D/d ≤ 1 ergänzt. Es kann gezeigt werden, dass die Massenabbrandraten multipler Feuer im Vergleich zu Einzelfeuern mit gleicher Brennstoffoberfläche bis zu einem Faktor 5.9 (n-Heptan) und 1.6 (DTBP) erhöht sind. Die Erhöhung ist abhängig vom relativen Abstand zwischen den Pools D, der Anzahl der Pools N und vom jeweiligen Brennstoff und zeigt ein lokales Maximum, welches mit dem Merging-Bereich der Flammenverschmelzung zusammenfällt. Die Massenabbrandrate als Funktion des relativen Abstandes zwischen den Pools kann durch eine Vergrößerung der Flammenbodenoberfläche infolge Flammenverschmelzung erklärt werden.
Present work deals with the potential usage of peroxy-fuels (usually known as organic peroxides) in engine combustion processes. 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. Since they are thermally unstable and energetic their safety demands 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 in the complete absence of air i.e. anaerobically, smaller volume of combustion (chamber), oxygenated fuel quality and low emissions. In this study we introduce an idea to develop the components of an engine operating solely on peroxy-fuels. The engine concept is based on single and multiple injectors in a cylinder with special material coating to ensure a temperature controlled processing.