Computer Simulation and Validation of Fire Hazards in Fuel Tanks

2007 ◽  
Author(s):  
James Carter ◽  
Timothy Harrigan ◽  
S. K. Punwani
Keyword(s):  
Diesel Fuel ◽  
Laboratory Testing ◽  
Fire Hazard ◽  
Environmental Parameters ◽  
Fuel Tank ◽  
Normal Operation ◽  
Explosion Hazard ◽  
Fuel Temperature ◽  
Material Transport ◽  
Two Phase

Flammable materials such as gasoline, ethanol, and diesel fuel are commonly transported in bulk via rail. In many cases, pockets of vapor can be generated inside the tank that can present a hazard if spilled during a collision or other catastrophic accident. Vapor conditions above the Lower Explosive Limit (LEL) if exposed to an external ignition source can result in an explosion or fire. Alternately, residual vapors within a tank present an explosion hazard if not properly vented or inerted prior to maintenance activities. This paper summarizes a generalized study of hazards associated with flammable liquids using computation fluid dynamics (CFD) to predict vapor conditions within a tank or following a spill. The analysis was verified in laboratory testing using scaled tank geometries. A demonstration case was developed using diesel fuel in a locomotive fuel tank. Typical road locomotives carry 3000–5000 gal of diesel fuel during normal operation. As the locomotive consumes fuel, large volumes are available for vapor generation within the tank. In a post-collision scenario, under ambient temperatures over the flash point of the fuel, the vapor that vents to the atmosphere presents a significant fire hazard. Further, flammable mists can be generated by the sprays that develop due to fuel leaks from a moving train. Studies of accident cases over a 10 year period indicated that a fire occurred in 80% of the accidents in which fuel was spilled. A CFD analysis was applied to the geometry associated with a locomotive fuel tank. The analysis models the two phase flow using the “volume of fluid” formalism in Fluent, and using a user defined diesel fuel evaporation algorithm. The tank and environmental parameters included fuel volume, fuel temperature, and air flow within the tank, and critical values of vapor content, temperature and velocity were plotted. The analysis predicted ignition of the external vapor cloud at temperatures relevant to a spill in a summer environment in the southwest, and propagation of the flame into the fuel tank. Laboratory testing confirmed the analysis: Once ignited, a flame propagated into the tank, causing an explosion and fire. The analysis methods developed can be applied to a variety of geometries and fluids, providing a basis for full scale testing. The overall intent of the analysis is to aid in the development of fire mitigation approaches for fuel and flammable material transport that would be practical for railroad use.

Assessment of Fire Hazards and Mitigation Methods in Locomotive Fuel Tanks

2011 ◽  
Author(s):  
Basant K. Parida ◽  
James Carter ◽  
Abdullatif K. Zaouk ◽  
John Punwani
Keyword(s):  
Diesel Fuel ◽  
Fire Hazard ◽  
Normal Operation ◽  
Vapor Concentration ◽  
Potential Hazard ◽  
Partial Recovery ◽  
Fire Hazards ◽  
Operational Conditions ◽  
Fuel Loss ◽  
Fuel Tanks

Diesel fuel carriage in locomotives, while safe in normal operational conditions, presents a potential hazard in the event of serious accident or derailment. Development of an effective mitigation method against this hazard requires an understanding of operational conditions that lead to fuel spill and fire. This paper describes a study of fire hazard stemming from rail accidents and potential approaches to mitigation. Data for the study was obtained from a large sample of National Transportation Safety Board (NTSB) investigation reports for accidents involving both freight and passenger locomotive accidents over a 10-year period. Approximately 25% of the events reviewed resulted in fuel release. In addition, of the events that resulted in fuel loss, a large majority (almost 70%) resulted in fire. Most cases with major fires led to loss of life and/or property, including destruction of multiple locomotives. Typical road locomotives carry 3,000–4,500 gallons of diesel fuel during normal operation. As the locomotive consumes fuel, large volumes are available for vapor generation within the tank. In a post-collision scenario, the vapor that vents to the atmosphere at temperatures close to flash point of the fuel presents a significant fire hazard. Further, flammable mists can be generated by the sprays that develop due to fuel leaks from the post-impact movement of a train. Previous laboratory tests on a scaled tank demonstrated that fire in a fuel-rich vapor can flash back inside the tank causing an explosion or a large fire. This paper also assesses potential technologies to prevent or mitigate fire hazards in locomotive fuel tanks. These include fuel tank leak prevention or reduction of outflow from breached fuel tanks, monitoring vapor concentration within fuel tanks, and limiting vapor concentrations inside tank to maintain levels below the Lower Explosive Limit (LEL). Potential benefits of the latter method include minimization of pollution from escaping vapor as well as partial recovery of reusable fuel from vapor.

Evaluating the Potential for Gasoline Geysering From Small Engine Fuel Tanks

2017 ◽  
Vol 4 (2) ◽  
Author(s):  
Todd M. Hetrick ◽  
Suzanne A. Smyth ◽  
Russell A. Ogle ◽  
Juan C. Ramirez
Keyword(s):  
Liquid Fuel ◽  
Waste Heat ◽  
Fire Hazard ◽  
Fuel Tank ◽  
Engine Fuel ◽  
Two Phase ◽  
Lawn Mower ◽  
Vehicle Systems ◽  
Fuel Tanks

This paper explores an infrequently encountered hazard associated with liquid fuel tanks on gasoline-powered equipment using unvented fuel tanks. Depending on the location of fuel reserve tanks, waste heat from the engine or other vehicle systems can warm the fuel during operation. In the event that the fuel tank is not vented and if the fuel is sufficiently heated, the liquid fuel may become superheated and pose a splash hazard if the fuel cap is suddenly removed. Accident reports often describe the ejection of liquid as a geyser. This geyser is a transient, two-phase flow of flashing liquid. This could create a fire hazard and result in splashing flammable liquid onto any bystanders. Many existing fuel tank systems are vented to ambient through a vented tank cap. It has been empirically determined that the hazard can be prevented by limiting fuel tank gauge pressure to 10 kPa (1.5 psi). However, if the cap does not vent at an adequate rate, pressure in the tank can rise and the fuel can become superheated. This phenomenon is explored here to facilitate a better understanding of how the hazard is created. The nature of the hazard is explained using thermodynamic concepts. The differences in behavior between a closed system and an open system are discussed and illustrated through experimental results obtained from two sources: experiments with externally heated fuel containers and operation of a gasoline-powered riding lawn mower. The role of the vented fuel cap in preventing the geyser phenomenon is demonstrated.

Assessment of a Diesel Vapor Reclamation System for Use in Diesel Electric Locomotives

2012 ◽  
Author(s):  
Basant K. Parida ◽  
Abdullatif K. Zaouk ◽  
John Punwani ◽  
Dana Maryott
Keyword(s):  
Real Time ◽  
Diesel Fuel ◽  
Fire Hazard ◽  
Research Effort ◽  
Temperature Data ◽  
Fuel Vapor ◽  
Development Effort ◽  
Fuel Temperature ◽  
The Real ◽  
Reclamation System

Diesel fuel used in locomotives generally does not pose a fire hazard. However, diesel vapor generated within tank vapor space attains flammability condition as the fuel temperature gets closer to the fuel-flash point, which may cause a fire hazard in the event of a tank breach due to collision or derailment of the locomotive. As a part of an ongoing Federal Railroad Administration (FRA) sponsored research effort, a proof-of-concept laboratory scale demonstration has shown that it is possible to circulate the mixture of diesel vapor and air through a small vapor condenser unit to reclaim the fuel vapor. The recovered fuel is shown to possess almost similar specific heat value and hydrocarbon constituents as that of neat diesel fuel and hence reusable. Furthermore, the vapor reclamation process enables mitigation of fire hazard and reduction of diesel vapor escape to the environment. In order to assess the real potential of diesel vapor reclamation on a running locomotive, real-time fuel temperature data was collected during a medium-haul run of a BNSF Railway freight locomotive. This paper presents the real-time fuel temperature data collected on a BNSF Railway instrumented locomotive tank as well as results of computational fluid dynamics (CFD) analyses performed for the full-scale locomotive tank. In continuation of the research and development effort, the design of a scaled up diesel vapor reclamation system is presented. The scope of its integration with a railroad freight locomotive is summarized and subsequent steps for its performance evaluation on a running locomotive are discussed.

scholarly journals Mechanical-Level Hardware-In-The-Loop and Simulation in Validation Testing of Prototype Tower Crane Drives

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5727
Author(s):  
Michał Michna ◽  
Filip Kutt ◽  
Łukasz Sienkiewicz ◽  
Roland Ryndzionek ◽  
Grzegorz Kostro ◽  
...  
Keyword(s):  
Laboratory Testing ◽  
Environmental Parameters ◽  
Experimental Tests ◽  
Drive System ◽  
Hardware In The Loop ◽  
Dynamic Simulations ◽  
Tower Crane ◽  
University Of Technology ◽  
New Type ◽  
Drive Systems

In this paper, the static and dynamic simulations, and mechanical-level Hardware-In-the-Loop (MHIL) laboratory testing methodology of prototype drive systems with energy-saving permanent-magnet electric motors, intended for use in modern construction cranes is proposed and described. This research was aimed at designing and constructing a new type of tower crane by Krupiński Cranes Company. The described research stage was necessary for validation of the selection of the drive system elements and confirmation of its compliance with applicable standards. The mechanical construction of the crane was not completed and unavailable at the time of testing. A verification of drive system parameters had to be performed in MHIL laboratory testing, in which it would be possible to simulate torque acting on the motor shaft. It was shown that the HIL simulation for a crane may be accurate and an effective approach in the development phase. The experimental tests of selected operating cycles of prototype crane drives were carried out. Experimental research was performed in the LINTE^2 laboratory of the Gdańsk University of Technology (Poland), where the MHIL simulator was developed. The most important component of the system was the dynamometer and its control system. Specialized software to control the dynamometer and to emulate the load subjected to the crane was developed. A series of tests related to electric motor environmental parameters was carried out.

Study of the influence of overvoltage on the quality of electricity in energy systems.

2020 ◽  
Vol 23 (2) ◽  
pp. 52-58
Author(s):  
S. SKRYPNYK ◽  
Keyword(s):  
Power Supply ◽  
Fire Hazard ◽  
Lightning Discharge ◽  
Quality Standard ◽  
Normal Operation ◽  
Electrical Network ◽  
Modern World ◽  
Electrical Networks ◽  
The World

Our world with its high technologies has long been deeply dependent on the quality of electricity supply. In most countries of the world there are national power grids that combine the entire set of generating capacity and loads. This network provides the operation of household appliances, lighting, heating, refrigeration, air conditioning and transport, as well as the functioning of the state apparatus, industry, finance, trade, health services and utilities across the country. Without this utility, namely electricity, the modern world simply could not live at its current pace. Sophisticated technological improvements are firmly rooted in our lives and workplaces, and with the advent of e-commerce began the process of continuous transformation of the way individuals interact with the rest of the world. But with the achievement of intelligent technologies, an uninterrupted power supply is required, the parameters of which exactly meet the established standards. These standards maintain our energy security and create a reliable power system, that is maintaining the system in a trouble-free state. Overvoltage is the deviation of the rated voltage from the value of the corresponding quality standard (frequency, sinusoidal voltage and compliance of harmonics). Overvoltage in terms of fire hazard is one of the most dangerous emergency modes of electrical equipment, which causes conditions that in most cases are sufficient for the occurrence of fire hazards (exceeding the allowable voltage leads to disruption of normal operation or possible ignition). Against the background of deteriorating engineering systems, increased power consumption and poor maintenance, power supply of electrical installations, the main causes of overvoltage in electrical networks are thunderstorms (atmospheric overvoltage), switching switches, uneven phase load in electrical networks, etc. The physical picture of internal overvoltage is due to oscillatory transients from the initial to the established voltage distributions in the conductive sections due to the different situation in the electrical circuit. In the conditions of operation of electric networks planned, mode or emergency situations are possible. Therefore, the ranges of overvoltage are determined by the range from several hundred volts to tens and hundreds of kilovolts, and depend on the types of overvoltage. Atmospheric overvoltage is considered to be one of the most dangerous types of emergency modes of operation of the electrical network. This overvoltage occurs as a result of lightning discharge during precipitation by concentrating electricity on the surface of the object, the introduction of potential through engineering networks and

Analysis of the vaporization processes in the vehicle fuel tank. New equation for determining the vapor amount

Trudy NAMI ◽  
2021 ◽  
pp. 74-86
Author(s):  
G. G. Ter-Mkrtich'yan
Keyword(s):  
Saturated Vapor ◽  
Barometric Pressure ◽  
Fuel Tank ◽  
Hazardous Substances ◽  
Practical Significance ◽  
Fuel Vapor ◽  
Hydrocarbon Emissions ◽  
Fuel Temperature ◽  
Vapor Generation ◽  
Initial Fuel

Introduction (problem statement and relevance). Hydrocarbon emissions from vaporizationtank fuel contribute significantly to the total emissions of hazardous substances from vehicles equipped with spark ignition engines. To meet the established standards for limiting hydrocarbon emissions caused by evaporation, all modern vehicles use fuel vapor recovery systems, the optimal parameters of which require the availability and application of mathematical models and methods for their determination.The purpose of the research was to develop a model of vapor generation processes in the car fuel tank and a methodology for determining the main quantitative parameters of the vapor-air mixture.Methodology and research methods. The analysis of the processes of vapor generation in the fuel tank was carried out. It was shown that the mass of hydrocarbons generated in the steam space was directly proportional to its volume and did not depend on the amount of fuel in the tank.Scientific novelty and results. New analytical dependences of the vaporization amount on the saturated vapor pressure, barometric pressure, initial fuel temperature and fuel heating during parking have been obtained.Practical significance. A formula was obtained to estimate the temperature of gasoline boiling starting in the tank, depending on the altitude above sea level and the volatility of gasoline, determined by the pressure of saturated vapors. Using the new equations, the vaporization analysis in real situations (parking, idling, refueling, explosive concentration of vapors) was carried out.

Numerical Simulation of Subcooled Flow Boiling Heat Transfer in Helical Tubes

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Jong Chull Jo ◽  
Woong Sik Kim ◽  
Chang-Yong Choi ◽  
Yong Kab Lee
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Steam Generator ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Heat Transfer Analysis ◽  
Normal Operation ◽  
Phase Flow ◽  
Two Phase ◽  
Side Flow

This paper addresses the numerical simulation of two-phase flow heat transfer in the helically coiled tubes of an integral type pressurized water reactor steam generator under normal operation using a computational fluid dynamics code. The shell-side flow field where a single-phase fluid flows in the downward direction is also calculated in conjunction with the tube-side two-phase flow characteristics. For the calculation of tube-side two-phase flow, the inhomogeneous two-fluid model is used. Both the Rensselaer Polytechnic Institute wall boiling model and the bulk boiling model are implemented for the numerical simulations of boiling-induced two-phase flow in a vertical straight pipe and channel, and the computed results are compared with the available measured data. The conjugate heat transfer analysis method is employed to calculate the conduction in the tube wall with finite thickness and the convections in the internal and external fluids simultaneously so as to match the fluid-wall-fluid interface conditions properly. Both the internal and external turbulent flows are simulated using the standard k-ε model. From the results of the present numerical simulation, it is shown that the bulk boiling model can be applied to the simulation of two-phase flow in the helically coiled steam generator tubes. In addition, the present simulation method is considered to be physically plausible in the light of discussions on the computed results.

scholarly journals Flammability parameters of sprayed and foam aerosols selected for studies

2018 ◽  
Vol 247 ◽  
pp. 00029
Author(s):  
Bozena Kukfisz
Keyword(s):  
Retention Time ◽  
Fire Hazard ◽  
Classification Criteria ◽  
Flame Height ◽  
Explosion Hazard ◽  
Confined Space ◽  
Combustion Heat ◽  
The Moment ◽  
Flammability Parameters ◽  
Propane Butane

The paper presents classification criteria for flammability parameters of sprayed and foamed aerosols [1-3]. Tests were carried out to determine such flammability criteria, as combustion heat of a substance, distance of sprayed aerosol from the ignition source at which ignition takes place, time equivalent necessary for ignition to take place and the density of deflagration for sprayed aerosols. For foamed aerosols the determined parameters comprised combustion heat parameters for a substance, the maximum flame height and the flame retention time. Based on the obtained flammability it may be unequivocally stated that aerosol products pose a serious fire hazard. Aerosols selected for testing pose a serious explosion hazard within a confined space. It seems that from among all the tested aerosols the most hazardous products in this respect comprise solvent and stain remover and DW 40. Within a space of 200 dm3 those products required 3 and 4 seconds of aerosol spraying respectively until the moment of initiating an explosion. Aerosol products in which use was made of propane-butane a carrier gas characterise by very similar flammability and explosivitiy parameters within a closed or confined space.

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