On the dominant mode of heat transfer in downward flame spread

An experimental study on downward flame spread over extruded polystyrene (XPS) foam at a high elevation is presented. The flame shape, flame height, mass loss rate and flame spread rate were measured. The influences of width and high altitude were investigated. The flame fronts are approximately horizontal. Both the intensity of flame pulsation and the average flame height increase with the rise of sample width. The flame spread rate first drops and then rises with an increase in width. The average flame height, mass loss rate and flame spread rate at the higher elevation is smaller than that at a low elevation, which demonstrates that the XPS fire risk at the higher elevation area is lower. The experimental results agree well with the theoretical analysis. This work is vital to the fire safety design of building energy conservation system.

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Bounds for Downward Flame Spread Rate in Solid Fuels and Comparison to Experiments

Combustion Science and Technology ◽

10.1080/00102202.2011.584089 ◽

2011 ◽

Vol 183 (10) ◽

pp. 1083-1106 ◽

Cited By ~ 6

Author(s):

Toni Pujol ◽

Bruna Comas

Keyword(s):

Flame Spread ◽

Solid Fuels ◽

Spread Rate ◽

Flame Spread Rate ◽

Downward Flame Spread

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Flame inhibition by calcium compounds: Effects of calcium compounds on downward flame spread over solid cellulosic fuel

Fire Safety Journal ◽

10.1016/j.firesaf.2019.102865 ◽

2019 ◽

Vol 109 ◽

pp. 102865 ◽

Cited By ~ 1

Author(s):

Yusuke Koshiba ◽

Takuya Haga ◽

Hideo Ohtani

Keyword(s):

Flame Spread ◽

Flame Inhibition ◽

Calcium Compounds ◽

Downward Flame Spread

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Combined Conduction and Radiation Heat Transfer in Porous Materials Heated by Intense Solar Radiation

Journal of Solar Energy Engineering ◽

10.1115/1.3267649 ◽

1985 ◽

Vol 107 (1) ◽

pp. 29-34 ◽

Cited By ~ 42

Author(s):

L. K. Matthews ◽

R. Viskanta ◽

F. P. Incropera

Keyword(s):

Heat Transfer ◽

Radiation Heat Transfer ◽

Plane Layer ◽

Single Scattering ◽

Dominant Mode ◽

Radiative Properties ◽

Maximum Temperature ◽

Transfer Model ◽

Radiation Heat ◽

Flux Approximation

An analysis is presented to predict the heat transfer characteristics of a plane layer of a semitransparent, high-temperature, porous material which is irradiated by an intense solar flux. A transient, combined conduction and radiation heat transfer model, which is based on a two-flux approximation for the radiation, is used to predict the temperature distribution and heat transfer in the material. Numerical results have been obtained using thermophysical and radiative properties of zirconia as a typical material. The results show that radiation is an important mode of heat transfer, even when the opacity of the material is large (τL > 100). Radiation is the dominant mode of heat transfer in the front third of the material and comparable to conduction toward the back. The semitransparency and high single scattering albedo of the zirconia combine to produce a maximum temperature in the interior of the material.

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