Fuel Particle Heat Transfer Part 2: Radiation and Convection during Spreading Laboratory Fires

Cohen, Jack D.; Finney, Mark A.

doi:10.1080/00102202.2021.2019232

Cited by 2 publications

(4 citation statements)

References 31 publications

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“…The vegetation's volume (V ) was measured by the water immersion method. 24 Then, the surface area (A s ) was calculated as 4V /D with a volume reading error estimated as 61 cm 3 . The mean stem diameter is about three times the mean foliage diameter, whereas the surface area ratio of stem to foliage is about nine averaged in all specimens.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…1 Particularly under wind-driven conditions, and for thin fuels, convection can significantly contribute to this heating process. 2,3 Thus, characterizing this convective heating becomes a critical component of a generalized physical description of wildland fire behavior. Water evaporation from wet fuels produces dry fuels, while at the same time, dry fuels are subject to pyrolysis and combustion.…”

Section: Introductionmentioning

confidence: 99%

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Forced convective heat transfer in vegetation by measuring liquid water evaporation

Sung,

Mueller,

Hamins

2023

Journal of Fire Sciences

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A series of experiments was conducted to develop a method to estimate the convective heat transfer in vegetative fuels with a complex geometry through the measurement of liquid water evaporation. A water mist was sprayed onto vegetative test specimens, coating their entire surface with a thin water layer. The water evaporation rate was measured using a load cell in a wind tunnel under controlled conditions while an infrared camera tracked the surface temperatures. Convective heat transfer was calculated by the difference between the free stream and surface temperatures and the measured evaporation rate, considering the energy balance of the water layer at steady state. The method was verified through evaporation tests using a wood cylinder array. Experiments were conducted using nominally 30 cm branches of a typical conifer, Norway Spruce ( Picea abies), yielding the conventional form of the Nusselt number–Reynolds number power–law relationship: Nu=C Ren Pr1/3 with coefficients C = 0.69 ± 0.25 and n = 0.34 ± 0.06.

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Section: Experimental Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Forced convective heat transfer in vegetation by measuring liquid water evaporation

Sung,

Mueller,

Hamins

2023

Journal of Fire Sciences

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“…Past laboratory-based studies of heat transfer in wildland fuels have employed a wide range of approaches (Fons et al , 1962Fons 1963;McCarter and Broido 1965;Thomas et al 1965;Rothermel and Anderson 1966;Van Wagner 1967;Anderson 1969;Fang and Steward 1969;Konev and Sukhinin 1977;Vaz et al 2004;Morandini et al 2005;Frankman et al 2010;Dupuy and Marechal 2011;Silvani et al 2012;Morandini et al 2013;Overholt et al 2014;Finney et al 2015;Tihay et al 2014;Liu et al 2015;Morandini et al 2018;Silvani et al 2018;Campbell-Lochrie et al 2018;Bu et al 2021;He et al 2021;Cohen and Finney 2022a), as summarised in Fig. 1.…”

Section: Heat Transfer In Porous Fuel Bedsmentioning

confidence: 99%

“…A maximum peak radiant heat flux at the top surface of the fuel bed of 11 kW/m 2 was measured for the fuel bed of 1.6 kg/m 2 fuel loading. It should be considered, however, that past studies have shown that even relatively low imposed radiant fluxes can significantly influence the flame spread rate (a summary of studies in various fuel types was previously provided by Drysdale (2011)), although further investigation and understanding of the heating response of vegetation particles is required (see for example (Cohen and Finney 2022a)).…”

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confidence: 99%

Effects of fuel bed structure on heat transfer mechanisms within and above porous fuel beds in quiescent flame spread scenarios

Campbell-Lochrie

Walker-Rávena²,

Gallagher³

et al. 2023

Int. J. Wildland Fire

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Background. Further understanding of the effect of fuel structure on underlying physical phenomena controlling flame spread is required given the lack of a coherent porous flame spread theory. Aims. To systematically investigate the effect of fuel structure on the heat transfer mechanisms within and above porous fuel beds. Methods. Radiant and total heat fluxes were measured in two extended series of laboratory-based quiescent flame spread experiments in pine needle beds across a range of structural conditions (various fuel loadings, bulk densities, and fuel depths). Key results. Peak radiant heat fluxes from the in-bed combustion region were greater than peak radiant heat fluxes from the above-bed flame front for all of the studied fuel conditions. However, the magnitude and duration of radiant heating from the above-bed flame increased with fuel loading (where bulk density was held constant and fuel depth allowed to vary). Conclusions. Our study highlighted the important role of fuel structure on heat transfer mechanisms, and the relevance of development of semi-empirical and simplified physics-based models. Implications. The interdependent effects of fuel bed properties on the underlying heat transfer mechanisms must be considered in the further development of coherent, flame spread theories.

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Fuel Particle Heat Transfer Part 2: Radiation and Convection during Spreading Laboratory Fires

Cited by 2 publications

References 31 publications

Forced convective heat transfer in vegetation by measuring liquid water evaporation

Forced convective heat transfer in vegetation by measuring liquid water evaporation

Effects of fuel bed structure on heat transfer mechanisms within and above porous fuel beds in quiescent flame spread scenarios

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