Numerical Modeling of Fire Suppression Using Water Mist. 3. Methanol Liquid Pool Fire Model PDF Download
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Author: Kuldeep Prasad
Publisher:
ISBN:
Category :
Languages : en
Pages : 37
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Book Description
This report is the third in a series dealing with the numerical modeling of fire suppression using water mist. In the first report, a numerical study was described for obtaining a detail understanding of the physical processes involved during the interaction of water-mist and methane-air diffusion flames. The relative contribution of the various Suppression mechanisms was studied and detailed comparison with experimental results was provided. The second report described a computational study for optimizing water-mist injection characteristics for Suppression of co-flow diffusion flames. The effect of droplet diameter, mist injection angle (throw angle), mist density and velocity on water-mist entrainment into the flame and flame Suppression were quantified. Numerical results were presented for symmetric and asymmetric spray pattern geometries resulting from base injection and side injection nozzle orientation. The focus of this report is on numerical modeling of methanol liquid pool fires. A mathematical model is first developed to describe the evaporation and burning of liquid methanol. Then, the complete set of unsteady, compressible Navier-Stokes equations for reactive flows are solved in the gas phase to describe the convection of the fuel gases away from the pool surface, diffusion of the gases into the surrounding air and the oxidation of the fuel molecules into product species. Heat transfer into the liquid pool and the metal container through conduction, convection and radiation are modeled by solving a modified form of the energy equation. Clausius-Clapeyron relationships are invoked to model the evaporation rate of a two-dimensional pool of pure liquid methanol. The governing equations along with appropriate boundary and interface conditions are solved using the Flux Corrected Transport algorithm. Numerical results exhibit a flame Structure that compares well with experimental observations.
Author: Kuldeep Prasad
Publisher:
ISBN:
Category :
Languages : en
Pages : 37
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Book Description
This report is the third in a series dealing with the numerical modeling of fire suppression using water mist. In the first report, a numerical study was described for obtaining a detail understanding of the physical processes involved during the interaction of water-mist and methane-air diffusion flames. The relative contribution of the various Suppression mechanisms was studied and detailed comparison with experimental results was provided. The second report described a computational study for optimizing water-mist injection characteristics for Suppression of co-flow diffusion flames. The effect of droplet diameter, mist injection angle (throw angle), mist density and velocity on water-mist entrainment into the flame and flame Suppression were quantified. Numerical results were presented for symmetric and asymmetric spray pattern geometries resulting from base injection and side injection nozzle orientation. The focus of this report is on numerical modeling of methanol liquid pool fires. A mathematical model is first developed to describe the evaporation and burning of liquid methanol. Then, the complete set of unsteady, compressible Navier-Stokes equations for reactive flows are solved in the gas phase to describe the convection of the fuel gases away from the pool surface, diffusion of the gases into the surrounding air and the oxidation of the fuel molecules into product species. Heat transfer into the liquid pool and the metal container through conduction, convection and radiation are modeled by solving a modified form of the energy equation. Clausius-Clapeyron relationships are invoked to model the evaporation rate of a two-dimensional pool of pure liquid methanol. The governing equations along with appropriate boundary and interface conditions are solved using the Flux Corrected Transport algorithm. Numerical results exhibit a flame Structure that compares well with experimental observations.
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Category : Fire extinction
Languages : en
Pages : 0
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Book Description
This report is the fourth in a series dealing with numerical modeling of fire suppression using water mist. While the first two reports examined the interaction of water mist with two-dimensional methane air diffusion flames, the third report presented a numerical model for studying methanol liquid pool fires, As shown in that report, numerical results exhibited a flame structure that compared well with experimental observations and thermocouple temperature measurements. In the present report we describe results for water-mist suppression of liquid methanol pool fires. The interaction of water-mist with pulsating pool fires is studied. Time dependent heat release rate profiles and temperature profiles identify the location where the water droplets evaporate and absorb energy. Numerical results are also presented for the effect of water mist on steady methanol pool fires stabilized by a strong co-flowing air jet. The relative contribution of the various suppression mechanisms such as oxygen dilution, radiation and thermal cooling on overall fire suppression is investigated. Parametric studies are performed to determine the effect of droplet injection density, velocity and droplet diameter on entrainment and overall suppression of pool fires. These results are reported in terms of reduction in peak temperature, effect on burning rate and changes in overall heat release rate. Numerical simulations indicate that small droplet diameters exhibit smaller characteristic time for decrease of relative velocity with respect to the gas phase, and therefore entrain most rapidly into the diffusion flame. Hence for the co-flow injection case, smaller diameter droplets produce maximum flame suppression for a fixed amount of injection spray density.
Author:
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ISBN:
Category :
Languages : en
Pages :
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Author: K. Prasad
Publisher:
ISBN:
Category :
Languages : en
Pages : 52
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This report is the first in a series dealing with the numerical modeling of fire suppression using water mist. The focus of this report is on the suppression of gas jet diffusion flames using fine water droplets. A two continuum formulation is used in which the gas phase and the water mist are both described by equations of the eulerian form. The model is used to obtain a detail understanding of the physical processes involved during the interaction of water mist and flames. The relative contribution of various mist suppression mechanisms is studied. The effect of droplet diameter, spray injection density and velocity on water mist entrainment into the flames and flame suppression is quantified. Droplet trajectories are used to identify the regions of the flame where the droplets evaporate and absorb energy. Finally, the model is used to determine the water required for extinction, and this is reported in terms of the ratio of the water supply rate to the fuel flow rate.
Author:
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ISBN:
Category : Combustion
Languages : en
Pages : 954
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Author: Chuka Ndubizu
Publisher:
ISBN:
Category :
Languages : en
Pages : 32
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This report presents the results of an experimental and numerical parametric study of water mist suppression of liquid pool fires. The numerical part was conducted with small 2-D methanol pool fire, while the experiments were conducted with a 50 cm diameter pan heptane and JP8 pool fires. Analyses of results of the experimental and numerical parts lead to similar conclusions. First, the results show that base injection of droplets enhanced their suppression effectiveness by as much as two times compared to top injection. This is because the droplets evaporated within the lower region of the fire where a greater effect of oxygen dilution and water vapor higher heat capacity is fully realized. Secondly, the experimental results show that smaller droplets are more effective than larger droplets in both top and base injections. The similarity between the model predictions and the experimental data indicates that the results of the parametric study conducted with a small scale laminar pool fire can be useful in the design of water mist suppression systems for large scale fires. Finally, the experimental results show that water mist is more effective in suppressing JP8 fires than heptane fires. It is concluded that the difference in effectiveness is largely due to the additional effects of surface cooling.
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Category :
Languages : en
Pages : 0
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This report is the second in a series that discusses the numerical modeling of fire suppression using water-mist. In the first report, a numerical study was described for obtaining a detail understanding of the physical processes involved during the interaction of water-mist and flames. The relative contribution of the various suppression mechanisms for methane-air diffusion flames was studied and detailed comparison with experimental results was provided in the first report. The present report describes a computational study for optimizing water-mist injection characteristics for suppression of co-flow diffusion flames. A two-continuum formulation is used in which the gas phase and the water-mist are both described by equations of the Eulerian form. Numerical simulations are performed to optimize various water-mist injection characteristics for maximum flame suppression. The effects of droplet diameter, mist in injection angle (throw angle), mist density and velocity on water-mist entrainment into the flame and flame suppression are quantified. Droplet sectional trajectories and density contours are used to identify the regions of the flame where the droplets evaporate and absorb energy. Numerical results are presented for symmetric and asymmetric spray pattern geometries resulting from base injection and side injection nozzle orientation. Results indicate that smaller droplet diameters produce optimum suppression under base injection configuration, while larger droplet diameters are needed for optimum suppression for the side injection configuration. For all cases, the model is used to determine the water-mist required for extinction, and this is reported in terms of the ratio of the water supply rate to the fuel flow rate.
Author: Kuldeep Prasad
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: C. A. Brebbia
Publisher: WIT Press
ISBN: 1845647343
Category : Science
Languages : en
Pages : 557
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Book Description
Multiphase flows are found in all areas of technology, at all length scales and flow regimes and can involve compressible or incompressible linear or nonlinear, fluids. However, although they are ubiquitous, multiphase flows continue to be one of the most challenging areas of computational mechanics, with numerous problems as yet unsolved. Advanced computational and experimental methods are often required to solve the equations that describe such complex problems. The many challenges that must be faced in solving them include modelling nonlinear fluids, modelling and tracking interfaces, dealing with multiple length scales, characterising phase structures, and treating drop break-up and coalescence. It is important to validate models, which calls for the use of expensive and difficult experimental techniques.This book presents contributions on the latest research in the techniques for solving multiphase flow problems, presented at the seventh in a biennial series of conferences on the subject that began in 2001. Featured topics include: Flow in porous media; Turbulent flow; Multiphase flow simulation; Image processing; Heat transfer; Atomization; Interface behaviour; Oil and gas applications; Experimental measurements; Energy applications; Biological flows; Micro and macro fluids; Compressible flows.
Author: Dawei Zheng
Publisher: CRC Press
ISBN: 1315752239
Category : Nature
Languages : en
Pages : 292
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Book Description
The 2014 International Conference on Energy and Environment (ICEE 2014) was held June 26-27 in Beijing, China. The objective of ICEE 2014 was to provide a platform for researchers, engineers, academics as well as industry professionals from all over the world to present their research results and development activities in Energy and Environment res
