Pool Fires and Radiant Ignition Capability

1999 ◽  
Author(s):  
David G. Lilley
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Real World ◽  
Radiation Heat Transfer ◽  
Primary Reason ◽  
Pool Fires ◽  
Fire Growth ◽  
Radiation Heat ◽  
Present Contribution ◽  
Time Required

Abstract Radiation heat transfer is a primary reason for fire growth. Experimental data are needed to clarify the ignition potential and time required to ignite a particular “target” second item. The objective of the present contribution is to clarify how the size and material of a pool fire determine ignition distance capability, and exemplify realistic calculations related to real-world situations.

Analysis of Radiation Heat Transfer in an Enclosure Fire Including the Effect of Scattering

2005 ◽  
Author(s):  
W. W. Yuen ◽  
W. K. Chow
Keyword(s):  
Heat Transfer ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Radiation Heat Transfer ◽  
Zone Model ◽  
Fire Growth ◽  
Radiation Heat ◽  
Fire Zone ◽  
Enclosure Fire ◽  
Radiative Exchange

The need for an accurate simulation of the radiative heat transfer in a fire zone model is demonstrated. Results show that the lack of an accurate model of the relevant physics of radiative heat transfer can lead to uncertainty which can severely limit the usefulness of a fire zone model. An accurate numerical model of radiative exchange including the effect of scattering, is applied to simulate the effect of radiative heat transfer on fire growth. Typical conservation equations in a fire zone models are used.

Heat Transfer Across Opaque Fibers

2012 ◽  
Vol 134 (7) ◽  
Author(s):  
Krishpersad Manohar ◽  
Gurmohan S. Kochhar ◽  
David W. Yarbrough
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Thermal Conductivity ◽  
Fiber Diameter ◽  
Radiation Heat Transfer ◽  
Physical Parameters ◽  
Density Range ◽  
Radiation Heat ◽  
Apparent Thermal Conductivity ◽  
Air Conduction

Predicting the thermal conductivity of loose-fill fibrous thermal insulation is a complex problem, when considering the combined conduction, convection, and radiation heat transfer within a scattering, emitting, and absorbing medium. A piecewise model for predicting the overall apparent thermal conductivity of large diameter opaque fibrous materials was developed by considering the radiation heat transfer, solid conduction and air conduction components separately. The model utilized the physical parameters of emissivity, the density of the solid fiber material, the percentage composition and range of fiber diameter, and the mean fiber diameter to develop specific equations for piecewise contribution from radiation, solid fiber conduction, and air conduction toward the overall effective thermal conductivity. It can be used to predict the overall apparent thermal conductivity for any opaque fibrous specimen of density (ρ), known thickness (t), mean temperature (T), and temperature gradient (ΔΤ). Thermal conductivity measurements were conducted in accordance with ASTM C518 specifications on 52 mm thick, 254 mm square test specimens for coconut and sugarcane fibers. The test apparatus provided results with an accuracy of 1%, repeatability of 0.2%, and reproducibility of 0.5%. The model was applied to and compared with experimental data for coconut and sugarcane fiber specimens and predicted the apparent thermal conductivity within 7% of experimental data over the density range tested. The model also predicted the optimum density range for both coconut and sugarcane fibers.

Diffraction and Polarization Effects in Radiation Heat Transfer: A Case Study

2017 ◽  
Author(s):  
J. Robert Mahan ◽  
Anum R. Barki ◽  
Kory J. Priestley
Keyword(s):  
Heat Transfer ◽  
Earth Science ◽  
Optical Design ◽  
Radiation Heat Transfer ◽  
Low Earth Orbit ◽  
Radiation Heat ◽  
Present Contribution ◽  
Optical Effects ◽  
Usual Concept ◽  
Science Community

The Monte-Carlo ray-trace (MCRT) method is particularly well suited to the optical design of instrumentation in which very small radiant signals must be separated from a strong background. The present contribution explores an important application lying at the intersection of physical optics and radiation heat transfer. Specifically, we consider instruments intended to monitor the planetary energy budget from low earth orbit. To accommodate the increasingly exigent accuracy requirements imposed by the Earth science community, it has become necessary to include effects such as diffraction and polarization that are normally omitted in traditional radiation heat transfer modeling. This requires that the usual concept of a “ray” be extended to include wavelength, a phase angle, and polarization. A realistic instrument concept is considered that fully exercises the ability of such an approach to capture optical effects that are either ignored or assessed “offline” in traditional modeling efforts. Investigated is the range of variation of detector illumination when the effects of the source spectral content, diffraction, and polarization are included.

scholarly journals Comparison of soot radiation in diesel flame given by mathematical model and by experimental data

2007 ◽  
Vol 29 (3) ◽  
pp. 293-301
Author(s):  
Bui Van Ga ◽  
Tran Van Nam ◽  
Nguyen Ngoc Linh
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Mathematical Model ◽  
Combustion Chamber ◽  
Engine Speed ◽  
Soot Formation ◽  
Radiation Heat Transfer ◽  
Formation Model ◽  
Radiation Heat ◽  
Maximum Value

An integral unidirectional model is established to calculate radiation heat transfer of Diesel flame in the open air and in combustion chamber of engine. Based on the temperature and soot fraction given by the flamlet theory and soot formation model of Tesner-Magnussen, radiation of soot particulate cloud at different positions of flame is determined and compared with experimental data obtained by the two-color method.The results show that the radiation given by the model is 203 lower than that produced by experiments on the stationary flame in open air. Soot radiation intensity in the Diesel engine increases in function of load and engine speed regimes and its maximum value (about 2000 kW/m2) is reached when the highest pressure is attained in combustion chamber.

Validation of the Isis-3D Computer Code for Simulating Large Pool Fires Under a Variety of Wind Conditions

2004 ◽  
Vol 126 (3) ◽  
pp. 360-368 ◽  
Author(s):  
Miles Greiner ◽  
Ahti Suo-Anttila
Keyword(s):  
Heat Transfer ◽  
Reaction Rate ◽  
Radiation Heat Transfer ◽  
Temperature Response ◽  
Computer Code ◽  
Computational Grids ◽  
Model Parameters ◽  
Pool Fires ◽  
Radiation Heat ◽  
Transportation Risk

The Isis-3D computational fluid dynamics/radiation heat transfer computer code was developed to simulate heat transfer from large fires to engulfed packages for transportation risk studies. These studies require accurate estimates of the total heat transfer to an object and the general characteristics of the object temperature distribution for a variety of fire environments. Since risk studies require multiple simulations, analysis tools must be rapid as well as accurate. In order to meet these needs Isis-3D employs fuel evaporation reaction rate and radiation heat transfer models that allow it to accurately model large-fire heat transfer even when relatively coarse computational grids are employed. Reaction rate and soot radiation model parameters in Isis-3D have been selected based on experimental data. In this work, Isis-3D calculations were performed to simulate the conditions of three experiments that measured the temperature response of a 4.66 m diameter culvert pipe located at the leeward edge of 18.9 m and 9.45 m diameter pool fires in crosswinds with average speeds of 2.0, 4.6, and 9.5 m/s. Isis-3D accurately calculated the time-dependent temperatures in all three experiments. Accelerated simulations were performed in which the pipe specific heat was reduced compared to the measured value by a factor of four. This artificially increased the speed at which the pipe temperature rose and allowed the simulated fire duration to be reduced by a factor of four. A 700 sec fire with moderately unsteady wind conditions was accurately simulated in 10 hours on a standard workstation.

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