Transportation accidents and the resulting fires are an important field of study. At the University of Waterloo Live Fire Research Facility (UWLFRF), an experiment was conducted in partnership with Sandia National Laboratories in Albuquerque, New Mexico. This experiment was designed to simulate an aircraft accident where fuel is spilled on the runway and is subsequently ignited. A crosswind pushes the 2.0 m diameter pool fire towards the aircraft fuselage and the conditions around the fire are monitored. Literature on the subject is examined first, examining the relationship between the fire, the crosswind, and the 2.7 m diameter blocking object (aircraft fuselage). A full wind characterization is then presented of the UWLFRF both with and without the blocking object in place, using five distinct wind speeds ranging from 3 m/s to 13.5 m/s. Turbulence intensity measurements are made on the centerline of the facility when possible. Details about the two sets of live fire tests are presented, a control experiment without the blocking object in place and then fire tests with the blocking object in place. Additionally, the control experiment has two different setups, one involving a floor surround in order to diminish the effect of the forward facing step on the front of the fuel pan. The fuel regression rate, the wind speed, the ambient conditions and the heat flux near the fuel pan are monitored during each live fire test. The fuel regression rate, defined as the rate at which the height of the liquid fuel level decreases as the fire burns, is then analyzed versus all other monitored variables. During no blocking object tests, trends of increasing wind speed and increasing heat flux on some gauges and decreasing flux on others was observed with increasing fuel regression rate when the floor surround was in place. During no blocking object tests without the floor surround and tests with the blocking object in place, no strong trends were observed when comparing the monitored variables. The ambient conditions were not observed to have an effect on any test. The average fuel regression for tests without the blocking object in place is 4.0 mm/min without the floor surround, and 4.4 mm/min with it in place. With the blocking object in place the average fuel regression rate was measured to be 4.8 mm/min using load cells and 4.1 mm/min using the sight glass.

Transportation accidents and the resulting fires are an important field of study. At the University of Waterloo Live Fire Research Facility (UWLFRF), an experiment was conducted in partnership with Sandia National Laboratories in Albuquerque, New Mexico. This experiment was designed to simulate an aircraft accident where fuel is spilled on the runway and is subsequently ignited. A crosswind pushes the 2.0 m diameter pool fire towards the aircraft fuselage and the conditions around the fire are monitored. Literature on the subject is examined first, examining the relationship between the fire, the crosswind, and the 2.7 m diameter blocking object (aircraft fuselage). A full wind characterization is then presented of the UWLFRF both with and without the blocking object in place, using five distinct wind speeds ranging from 3 m/s to 13.5 m/s. Turbulence intensity measurements are made on the centerline of the facility when possible. Details about the two sets of live fire tests are presented, a control experiment without the blocking object in place and then fire tests with the blocking object in place. Additionally, the control experiment has two different setups, one involving a floor surround in order to diminish the effect of the forward facing step on the front of the fuel pan. The fuel regression rate, the wind speed, the ambient conditions and the heat flux near the fuel pan are monitored during each live fire test. The fuel regression rate, defined as the rate at which the height of the liquid fuel level decreases as the fire burns, is then analyzed versus all other monitored variables. During no blocking object tests, trends of increasing wind speed and increasing heat flux on some gauges and decreasing flux on others was observed with increasing fuel regression rate when the floor surround was in place. During no blocking object tests without the floor surround and tests with the blocking object in place, no strong trends were observed when comparing the monitored variables. The ambient conditions were not observed to have an effect on any test. The average fuel regression for tests without the blocking object in place is 4.0 mm/min without the floor surround, and 4.4 mm/min with it in place. With the blocking object in place the average fuel regression rate was measured to be 4.8 mm/min using load cells and 4.1 mm/min using the sight glass.

A suite of models were integrated to predict the potential of a large liquid hydrocarbon storage tank fire escalating and involving neighbouring tanks, as a result of thermal loading. A steady state pool fire radiant heat model was combined with a further model, in order to predict the distribution of thermal loading over the surface of an adjacent tank, and another model was incorporated to predict the thermal response of the contents of the adjacent tank. In order to predict if, or when, an adjacent tank will ignite, the radiant heat from the fire received by the adjacent tank must be quantified. There are a range of mathematical models available in the literature to calculate the radiant heat flux to a specified target and each of these models is based on assumptions about the fire. The performance of three of these models, which vary in complication, was analysed (the single point source model, the solid flame model and the fire dynamics simulator computational fluid dynamics model) and, in order to determine the performance of each model, the predictions made by each of the models were compared with actual experimental measurements of radiant heat flux. Experiments were undertaken involving different liquid fuels and under a range of weather conditions and, upon comparing the predictions of the models with the experimental measurements, the solid flame model was found to be the one most appropriate for safety assessment work. Thus, the solid flame model was incorporated into the thermal loading model, in order to predict the distribution of radiant heat flux falling onto an adjacent tank wall and roof. A model was developed to predict the thermal response of the contents of an adjacent tank, in order to predict variations in the liquid and vapour temperature, any increase in the vapour space pressure and the evolution of the vapours within the given time and the distribution of thermal loading over the surface of the tank as predicted by previous models; of particular importance was the identification of the possibility of forming a flammable vapour/air mixture outside the adjacent tank. To assess the performance of the response model, experiments were undertaken at both laboratory and field scale. The laboratory experiments were conducted in the Chemical Engineering Laboratory at Loughborough University and required the design and construction of an experimental facility representing a small-scale storage tank exposed to an adjacent fire. The field scale experiments were undertaken at Centro Jovellanos, Asturias, Spain. An experimental vessel was designed and fabricated specifically to conduct the laboratory tests and to measure the response of a tank containing hydrocarbon liquids to an external heat load. The vessel was instrumented with a network of thermocouples and pressure transmitter and gauge, in order to monitor the internal pressure and distribution in temperature throughout the liquid and its variation with time. The model predicting the thermal response of an adjacent tank was shown to produce predictions that correlated with the experimental results, particularly in terms of the vapour space pressure and liquid surface temperature. The vapour space pressure is important in predicting the time when the vacuum/pressure valve opens, while the liquid surface temperature is important as it governs the rate of evaporation. Combining the three models (the Pool Fire model, the Thermal Loading model and the Response model) forms the basis of the storage tanks spacing international codes and presents a number of innovative features, in terms of assessing the response to an adjacent tank fire: such features include predicting the distribution of thermal load on tanks adjacent to the tank on fire and thermal load on the ground. These models can predict the time required for the opening of the pressure vacuum relief valve on adjacent tanks and the release of the flammable vapour/air mixture into the atmosphere. A wide range of design and fire protection alternatives, such as the water cooling system and the minimum separation distance between storage tanks, can be assessed using these models. The subsequent results will help to identify any recommended improvements in the design of facilities and management systems (inspection and maintenance), in addition to the fire fighting response to such fires.

Fire is one of the main hazards associated with storage tanks containing flammable liquids. These tanks are usually closely spaced and in large groups, so where a petroleum fire occurs, adjacent tanks are susceptible to damage leading to further development of the fire. The structural behaviour such as thermal stability and failure modes of the tanks under such fire scenario are very important to the safety design and assessment of oil depots. However, no previous studies on this problem are known to the best knowledge of the author. This thesis presents a systematic exploration of the potential thermal and structural behaviours of an oil tank when one of its neighbour tanks is on fire. Under such scenario, the oil tanks are found to easily buckle under rather moderate temperature rises. The causes of such buckling failures are the reduced modulus of steel at elevated temperatures, coupled with thermally-induced stresses due to the restraint of thermal expansion. Since the temperatures reached in such structures can be several hundred Centigrade degrees, any restraint to thermal expansion can lead to the development of compressive stresses. The high susceptibility of thin shell structures to elastic buckling under low compressive stresses means that this type of failure can be easily provoked. The main objectives of this thesis were to reveal the thermal distribution patterns developed in an oil tank under the heating from an adjacent tank fire, to understand the underlying mechanism responsible for the buckling of tank structure, and to explore the influences of various thermal and geometrical parameters on the buckling temperature of the tanks. The study began with analytical solutions for stresses and deformations in a partially filled roofless cylindrical tank under an idealised axisymmetrical heating regime involving thermal discontinuity at the liquid level. The results demonstrate that large compressive circumferential membrane stresses occur near the bottom boundary for an empty tank and near the liquid level for a partially-filled tank. Heat transfer analysis was conducted to explore the temperature distribution developed in the tank when the fire reaches a steady state. Parameters and assumptions used in the adopted pool fire model were carefully examined. The results show that a rather non-uniform distribution of temperature is developed in the tank especially around the tank circumference. A simple model was then proposed to describe the temperature distribution based on the numerical heat transfer analysis. The accuracy of the proposed temperature distribution model for predicting the structure behaviour was evaluated by comparing its predictions with those using directly the temperature distribution obtained from the numerical heat transfer analysis. Extensive geometric and material nonlinear analyses were carried out to capture the buckling behaviour of the tank using both the proposed temperature distribution and that from heat transfer analysis. It was found large vertical compressive membrane stresses are induced in the tank, causing buckling. The influence of fire diameter, location, liquid filling level and tank geometry were investigated.

Liquefied Natural Gas (LNG) hazards include LNG flammable vapor dispersion and LNG pool fire thermal radiation. A large LNG pool fire emits high thermal radiation thus preventing fire fighters from approaching and extinguishing the fire. One of the strategies used in the LNG industry and recommended by federal regulation National Fire Protection Association (NFPA) 59A is to use expansion foam to suppress LNG vapors and to control LNG fire by reducing the fire size. In its application, expansion foam effectiveness heavily depends on application rate, generator location, and LNG containment pit design. Complicated phenomena involved and previous studies have not completely filled the gaps increases the needs for LNG field experiments involving expansion foam. In addition, alternative LNG vapor dispersion and pool fire suppression methodology, Foamglas® pool fire suppression (PFS), is investigated as well. This dissertation details the research and experiment development. Results regarding important phenomena are presented and discussed. Foamglas® PFS effectiveness is described. Recommendations for advancing current guidelines in LNG vapor dispersion and pool fire suppression methods are developed. The gaps are presented as the future work and recommendation on how to do the experiment better in the future. This will benefit LNG industries to enhance its safety system and to make LNG facilities safer.

Liquefied Natural Gas (LNG) is flammable when it forms a 5 – 15 percent volumetric concentration mixture with air at atmospheric conditions. When the LNG vapor comes in contact with an ignition source, it may result in fire and/or explosion. Because of flammable characteristics and dense gas behaviors, expansion foam has been recommended as one of the safety provisions for mitigating accidental LNG releases. However, the effectiveness of foam in achieving this objective has not been sufficiently reported in outdoor field tests. Thus, this research focused on experimental determination of the effect of expansion foam application on LNG vapor dispersion and pool fire. Specifically, for evaluating the use of foam to control the vapor hazard from spilled LNG, this study aimed to obtain key parameters, such as the temperature changes of methane and foam and the extent reduction of vapor concentration. This study also focused on identifying the effectiveness of foam and thermal exclusion zone by investigating temperature changes of foam and fire, profiles of radiant heat flux, and fire height changes by foam. Additionally, a schematic model of LNG-foam system for theoretical modeling and better understanding of underlying mechanism of foam was developed. Results showed that expansion foam was effective in increasing the buoyancy of LNG vapor by raising the temperature of the vapor permeated through the foam layer and ultimately decreasing the methane concentrations in the downwind direction. It was also found that expansion foam has positive effects on reducing fire height and radiant heat fluxes by decreasing fire heat feedback to the LNG pool, thus resulting in reduction in the safe separation distance. Through the extensive data analysis, several key parameters, such as minimum effective foam depth and mass evaporation rate of LNG with foam, were identified. However, caution must be taken to ensure that foam application can result in initial adverse effects on vapor and fire control. Finally, based on these findings, several recommendations were made for improving foam delivery methods which can be used for controlling the hazard of spilled LNG.

The UK Health & Safety Executive are responsible for advising on ways to ensure the safety of employees within the workplace. One of the main areas of concern is the potential problem of unwanted fire, and it has been identified that within the area of large-scale storage in warehouses, there is an uncertainty posed by large quantities of thermoplastic. Some forms of thermoplastic exhibit melt-flow behaviour when heated, and a large vertical array exposed to a fire may melt and ignite forming a pool fire in addition to a wall fire. This project is largely experimental, and aimed at quantifying the effect of a growing pool fire fuelled by a melting wall on overall fire growth rate. The pool fire has been found to increase melting and burning rates, producing a much faster growing fire. It has also been found that - 80% of flowing and burning material will enter a potential pool fire, with only 20 - 25% of total mass loss actually burning from the original array. During the project 400+ small-scale tests and several medium-scale experiments have been undertaken at both Edinburgh University and the HSE's Fire & Explosion Laboratory, Buxton. The experiments have confirmed the main parameters governing pool fire development are molecular weight degradation rate and mechanism, which control flow viscosity. There have also been investigations into other influences, the most significant of which was found to be flooring substrate. These parameters then form the basis of a simple 1-D model. A semi-infinite heat transfer approximation is used to determine temperature profile through a thermoplastic exposed to its own flame flux, with extrapolated temperature dependant material properties. The derived profile is then inserted into a gravity driven flow model, to produce estimates of flow rate and quantity for plastics undergoing either random or end chain scission thermal degradation processes. The model identifies property data which are required to permit its use as a hazard assessment tool.

<p><br></p> <p>A  combustion simulation involves various physiochemical processes, such as molecular and turbulent diffusion, smoke and soot formation, thermal radiation, chemical reaction mechanisms, and kinetics. In the last decade, computational fluid dynamics (CFD) has been increasingly used in combustion modeling. It is critically important to improve and enhance the predictive capabilities of combustion models. This work presents an analysis of two types of diffusion flames: the momentum-dominant jet flames and buoyancy-controlled pool fires. The gap between the existing knowledge of differential molecular diffusion in turbulent high momentum jet flow and the practical applications has been reduced. The importance of mixing modeling in pool fire simulations has been revealed, and enhancement for predicting fire extinction limits has been proposed.</p> <p><br></p> <p>Modeling differential molecular diffusion in turbulent non-premixed combustion remains a great challenge for flamelet models. The laminar flamelet is a key component of a flamelet model for turbulent combustion. One significant challenge that has not been well addressed is the representativity of laminar flamelet for the characteristics of differential molecular diffusion in turbulent combustion problems. Laminar flamelet is generated typically based on two conceptual burner configurations, the opposed jet burner, and the Tsuji burner. They are commonly considered equivalent when dealing with the description of laminar flamelet structures. A difference between them is revealed in this work for the first time when they are used to represent differential molecular diffusion. The traditionally opposed jet burner yields an almost fixed equal diffusion location in the mixture fraction space for the transport of different elements. The Tsuji burner can produce a continuous variation of the equal diffusion location in the mixture fraction space with a slight extension. This variation of the equal diffusion location is shown to be an essential characteristic of turbulent non-premixed combustion, as demonstrated in a laminar jet mixing layer problem, a turbulent jet mixing layer problem, and a turbulent jet non-premixed flame. The Tsuji burner is thus potentially a more suitable choice than the opposed jet burner for laminar flamelet generation that can be consequently used in flamelet modeling of differential molecular diffusion for turbulent non-premixed combustion.</p> <p><br></p> <p>Capturing fire extinction limits in simulations is essential for developing predictive capabilities for fire. In this work, the combined large-eddy simulation (LES) and transported probability density function (PDF) methods are assessed for the predictions of fire extinction. The University of Maryland line burner is adopted as a validation test case. The NIST Fire Dynamics Simulator (FDS) code for LES is combined with an in-house PDF code called HPDF for the fire simulations. The simulation results were verified by using the available experimental data. The combustion efficiency under the different oxygen depletion levels in the oxidizer is analyzed. Fire extinction occurs when the oxygen depletion level reduces to a certain level. The model’s capability to capture this extinction limit is assessed by using the experimental data. Different mixing models and model parameters are examined. It is found that the fire extinction limit is very sensitive to the different mixing models and mixing parameters. The level of sensitivity is higher than in momentum-driven turbulent flames, which suggests the importance of mixing modeling in fire simulations. The existing mixing models need further enhancement for predicting fire extinction. </p> <p><br></p>

Yes / In this study, a Fuzzy Bayesian network (FBN) approach was proposed to analyze the domino effects of pool fire in storage tanks. Failure probabilities were calculated using triangular fuzzy numbers, the combined Center of area (CoA)/Sum-Product method, and the BN approach. Consequence modeling, probit equations, and Leaky-Noisy OR (L-NOR) gates were used to analyze the domino effects, and modify conditional probability tables (CPTs). Methanol storage tanks were selected to confirm the practical feasibility of the suggested method. Then the domino probability using bow-tie analysis (BTA), and FBN in the first and second levels was compared, and the Ratio of Variation (RoV) was used for sensitivity analysis. The probability of the domino effect in the first and second levels (FBN) was 0.0071472631 and 0.0090630640, respectively. The results confirm that this method is a suitable tool for analyzing the domino effects and using FBN and L-NOR gate is a good way for assessing the reliability of tanks. / National Petrochemical Company (NPC) of Iran

Submitted by JOSIANE SANTOS DE OLIVEIRA (josianeso) on 2018-04-04T12:31:51Z No. of bitstreams: 1 Rafael Gialdi Salvagni_.pdf: 4078552 bytes, checksum: 3046bf3bf4c04b0ca0ff91981f73727e (MD5) / Made available in DSpace on 2018-04-04T12:31:51Z (GMT). No. of bitstreams: 1 Rafael Gialdi Salvagni_.pdf: 4078552 bytes, checksum: 3046bf3bf4c04b0ca0ff91981f73727e (MD5) Previous issue date: 2017-04-25 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / PROSUP - Programa de Suporte à Pós-Gradução de Instituições de Ensino Particulares / Este trabalho apresenta o estudo numérico-experimental da dispersão de poluentes e da geometria da chama de uma poça de combustível. Foi realizada A modelagem da combustão em uma poça, com a dispersão da pluma em função do vento incidente, com o objetivo de caracterizar o fenômeno. Foi utilizado um túnel de vento em escala laboratorial para executar a análise experimental de poças de diesel (S-500) e biodiesel (B-100), em um tanque cilíndrico com tamanho reduzido de Ø110 x 57,4 mm. Além disso, foi utilizado o programa FDS para análise e comparação dos dados em escala de mesma grandeza da bancada experimental. A influência da velocidade do vento sobre a geometria da chama – inclinação, altura e comprimento – foi analisada, bem como outras questões pertinentes à estrutura da chama, como temperatura adimensional da chama, da pluma e temperatura periférica. Por último, uma análise da taxa de queima mássica foi feita para complementar os dados experimentais e obter mais informações sobre o comportamento da chama. Os dados experimentais foram aplicados nas correlações semi-empíricas de comprimento e ângulo de chama, a fim de comparar seu comportamento com a previsão de outros autores. Foi observado nos experimentos que, com a mudança da geometria da chama, ocorre a mudança da posição e consequentemente da dispersão da pluma. O ângulo da chama mostrou variação diretamente proporcional à velocidade do escoamento. A variação da altura e comprimento de chama foi inversamente proporcional à velocidade do escoamento. Os comportamentos do ângulo e da altura concordaram com a literatura, mas o comprimento apresentou diferenças. A temperatura adimensional da chama aumentou com o aumento da velocidade, sendo a do biodiesel 49% superior à do diesel. A temperatura adimensional da pluma apresentou um decremento com o aumento da velocidade de escoamento, atingindo, para o diesel, temperaturas cerca de 110% menores em relação ao biodiesel. A mesma tendência ocorreu com a temperatura periférica, que reduziu conforme aumentou a distância de medição da poça, havendo diferença de 20,3% entre os dois combustíveis. A taxa de queima mássica foi verificada e se observou que foi regida por diferentes mecanismos de trocas térmicas e flutuabilidade, o que provocou comportamentos diferentes para o diesel e o biodiesel, sendo as taxas de queima do diesel maiores, em geral. Os dados experimentais obtidos foram comparados com os resultados da análise numérica realizada no FDS. Obteve-se boas aproximações para o ângulo, comprimento, altura e temperaturas da pluma e periférica. As temperaturas da chama mostraram tendência diferente em relação aos dados experimentais. As análises de dispersão de poluentes mostraram uma tendência de redução abrupta das concentrações com o aumento da distância em velocidades menores e uma redução mais suave e constante para as maiores velocidades nos ensaios experimentais, apresentando, no entanto, uma grande diferença em relação aos valores numéricos, embora com tendências semelhantes, para ambos os combustíveis. / This work presents a numerical-experimental study of pollutants dispersion and flame geometry in a pool fire. Combustion modeling in a pool fire with plume dispersion as a function of the incident wind is carried out with the objective of phenomenon characterization. A laboratory-scale wind tunnel is used to perform the experimental analysis of diesel (S-500) and biodiesel (B-100) pool fire in a cylindrical tank with a reduced size of Ø110 x 57.4 mm. In addition, the FDS software was used to analyze and compare the results, using a model in a scale of the same magnitude of the experimental setup. The wind speed influence on the flame geometry – tilt angle, height and length – was analyzed as well as other questions related to the structure of the flame, such as dimensionless flame and plume temperature and outer layer temperature. Finally, an analysis of the mass burning rate was done to complement the experimental data and to obtain more information about the flame behavior. The data obtained were applied in the semi-empirical correlations of flame length and tilt angle to compare their behavior with the prediction of other authors. It Was observed that the change of flame geometry induces a change of plume position and dispersion. The behavior of the flame geometry was observed; the angle changes proportionally to the air flow speed. The variation in flame height and length was inversely proportional to air flow speed. The angle tilt and height agreed with the literature, but the length presented differences. The temperature of the flame increased with increasing of air flow speed being the values for biodiesel 49% higher than for diesel. The plume temperature presented a decrease with the increase of air flow speed, temperatures for diesel were about 110% smaller than for biodiesel. The same trend occurred with the measured outer layer temperature that reduced as the pool fire measurement distance increased, with a 20.3% difference between the fuels. The mass burning rate was governed by different mechanisms of heat feedback and buoyancy, which caused different behaviors for diesel and biodiesel, with diesel mass burning rates being higher in general. The experimental data obtained were compared with the results of the numerical analysis performed in the FDS software, and thus the numerical validation was done. The simulated results for tilt angle length, height and temperature of the plume and the outer layer agree well with experimental ones. The flame temperatures show an inverse trend in relation to experimental data. Pollutant dispersion analyzes showed a trend of abrupt reduction of concentration with increasing distance at lower air flow speed and a smoother and steady reduction at higher speeds, yet presenting a large discrepancy in relation to the numerical values for both fuels.