Development of an Atmospheric Dispersion Model for Heavier-Than-Air Gas Mixtures

Development of an Atmospheric Dispersion Model for Heavier-Than-Air Gas Mixtures

Author: Jerry A. Havens

Publisher:

Published: 1985

Total Pages: 183

ISBN-13:

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Mathematical modeling techniques use to predict atmospheric dispersion of heavy gases are reviewed and critiqued. These dispersion processes are characterized by three phases: (1) near field, negative buoyancy-domainated flow regime; (2) intermediate field, stably stratified shear flow regime; and (3) far field, passive turbulent diffusion regime. Mathematical models of laboratory and natural gravity currents are used to describe the negative buoyancy-dominated regime flow and dilution processes. A laboratory investigation of instantaneous heavy gas releases in calm air demonstrates scaling from small release volumes (0.5 cu m) to large field (2000 cu m) field releases, and is used to develop a mathematical model for the buoyancy-dominated regime. Laboratory data from stratified shear flow mixing experiments are used to develop a model for vertical diffusion of heavy gases in the atmospheric surface layer. The model concepts are consistent with the limiting passive behavior of demonstrated air pollution models. An interactive computer model for heavy gas dispersion (DEGADIS) is developed. The DEGADIS model accounts for the three regimes of heavy gas dispersion processes and can be used to simulate instantaneous, steady state, and transient releases. The model provides predictions of downwind concentration decay which are in good agreement with the full range of field experimental data currently available, and is recommended for incorporation in the Coast Guard hazard assessment computer system.


Scientific and Technical Aerospace Reports

Scientific and Technical Aerospace Reports

Author:

Publisher:

Published: 1994

Total Pages: 1028

ISBN-13:

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Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.


Guidelines for Use of Vapor Cloud Dispersion Models

Guidelines for Use of Vapor Cloud Dispersion Models

Author: CCPS (Center for Chemical Process Safety)

Publisher: John Wiley & Sons

Published: 2010-09-07

Total Pages: 293

ISBN-13: 0470935065

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The second edition of this essential reference updates and combines two earlier titles to capture the many technological advances for predicting the "footprint" of a vapor cloud release. Cited by EPA in its 1996 document, "Off-Site Consequence Analysis Guidance," the aim of the book is to encourage and facilitate the development and use of dispersion modeling as an everyday tool, providing practical understanding of basic physical and chemical principles, guidance in selecting release scenarios and the best available models, and information and examples on how to run some models and interpret outputs. Equally useful to beginners and experts, it compares 22 programs based on input from model developers, and presents 7 examples of typical accidental release scenarios. The book comes with a disk providing input and output data for scenarios.


Development of an Atmospheric Dispersion Model for Heavier-Than-Air Gas Mixtures. Volume 3. DEGADIS User's Manual

Development of an Atmospheric Dispersion Model for Heavier-Than-Air Gas Mixtures. Volume 3. DEGADIS User's Manual

Author: Jerry A. Havens

Publisher:

Published: 1985

Total Pages: 270

ISBN-13:

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The mathematical modeling techniques used to predict atmospheric dispersion of heavier-than-air gases discussed in Volume 1 are briefly summarized; these techniques are incorporated in an interactive computer model DEGADIS. Details of DEGADIS implementation are briefly discussed. The necessary input information to simulate a heavier-than-air gas release with DEGADIS is summarized. Example simulations of a steady state and transient release are included. A list of DEGADIS self-diagnostics with suggested actions are included. A listing of DEGADIS is included along with a partial list of program variables. Guidelines for installation of DEGADIS are presented.


LNG Risk Based Safety

LNG Risk Based Safety

Author: John L. Woodward

Publisher: John Wiley & Sons

Published: 2010-03-25

Total Pages: 392

ISBN-13: 047059022X

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The expert, all-inclusive guide on LNG risk based safety Liquefied Natural Gas (LNG) is the condensed form of natural gas achieved by cryogenic chilling. This process reduces gas to a liquid 600 times smaller in volume than it is in its original state, making it suitable for economical global transportation. LNG has been traded internationally and used with a good safety record since the 1960s. However, with some accidents occurring with the storage and liquefaction of LNG, a good understanding of its mechanisms, and its potential ramifications to facilities and to the nearby public, is becoming critically important. With an unbiased eye, this book leans on the expertise of its authors and LNG professionals worldwide to examine these serious safety issues, while addressing many false assumptions surrounding this volatile energy source. LNG Risk Based Safety: Summarizes the findings of the Governmental Accountability Office's (GAO) survey of nineteen LNG experts from across North America and Europe Reviews the history of LNG technology developments Systematically reviews the various consequences from LNG releases— discharge, evaporation, dispersion, fire, and other impacts, and identifies best current approaches to model possible consequence zones Includes discussion of case studies and LNG-related accidents over the past fifty years Covering every aspect of this controversial topic, LNG Risk Based Safety informs the reader with firm conclusions based on highly credible investigation, and offers practical recommendations that researchers and developers can apply to reduce hazards and extend LNG technology.


Development of an Atmospheric Dispersion Model for Heavier-Than-Air Gas Mixtures. Volume 2. Laboratory Calm Air Heavy Gas Dispersion Experiments

Development of an Atmospheric Dispersion Model for Heavier-Than-Air Gas Mixtures. Volume 2. Laboratory Calm Air Heavy Gas Dispersion Experiments

Author: Jerry A. Havens

Publisher:

Published: 1985

Total Pages: 269

ISBN-13:

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Laboratory experimental instantaneous releases of right circular cylindrical volumes of heavy gas (Freon-12/air) with initial volumes ranging from 0.034 cu m to 0.531 cu m and specific gravities ranging from 2.2 to 4.2 are described. Releases with initial height-to-diameter ratios of 0.4, 1.0, and 1.57 are reported. The heavy gas flow field surrounding the release is described by time series of gas concentration at various radial and vertical coordinates with respect to release center. Measurements of the gravity current velocities are determined from time-of-onset of measured gas concentration. Calm-air instantaneous heavy gas releases are demonstrated to scale with a characteristic length cube root of V sub i where V sub i is the initial volume, and a characteristic time (V sub i to the 1/6 power)/(sq root of the reduced gravitational acceleration). The scaled laboratory releases predict the gravity-spreading and dilution process occurring during the buoyancy-dominated flow phase of the 2000 cu/m Freon/air instantaneous releases conducted by the British Health and Safety Executive at Thorney Island, UK. The gravity spread and dilution data are used to validate the buoyancy-dominated flow submodel which is incorporated in DEGADIS, the general purpose heavy gas dispersion model developed for the Coast Guard.