Flame Extinction in a Ventilation-controlled Compartment

Loo, Alvin Si-Xian; Coppalle, A.; Aine, P.

doi:10.1016/j.proeng.2013.08.068

Cited by 14 publications

(4 citation statements)

References 12 publications

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“…The 21% oxygen concentration was kept during 180 s ensuring a stable combustion. Qualification tests have shown a limiting oxygen concentration about 14.5% closed to the literature values (Loo et al, 2013;Fourneau, 2013). Table 2 summarizes PMMA burning results, along with the time periods for averaging.…”

Section: Description Of Experimentssupporting

confidence: 47%

Effect of Oxygen on the Burning Behavior of Liquid and Solid Fuels in a Large-Scale Calorimeter

2019

JAFM

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The purpose of this experimental study was twofold: first, to explore and understand the effects of oxygen availability on the combustion of liquid and solid fuels; second, to provide data for comparison with CFD models. Experiments were conducted in the controlled-atmosphere calorimeter of IRSN, called CADUCEE, varying the oxygen concentration in the oxidizing stream and the size of the fire. Polymethylmethacrylate (PMMA) and heptane were used as fuels. Results are found to be in good agreement with the literature data. As the oxygen level decreases, the mass loss rate and flame heat feedback decrease, as well as the flame height and maximum flame temperature, for both fuels whatever the sample size. For heptane pool fires, temperature measurements in the liquid layer reveal a decrease in heat transfer at the fuel surface and inside the fuel with the oxygen molar fraction. For PMMA, the radiative and convective contributions to the total heat flux remain nearly constant, with about 65% and 35% respectively, regardless of sample size and oxygen concentration.

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Section: Description Of Experimentssupporting

confidence: 47%

Effect of Oxygen on the Burning Behavior of Liquid and Solid Fuels in a Large-Scale Calorimeter

2019

JAFM

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“…Several previous reports claimed the flame extinction behavior inside a compartment with complex flow (mixing) behavior as the consequence of oxygen lean inside the compartment [33,34].…”

Section: Theoretical Analysis and Model On Critical Fuel Mass Flow Ramentioning

confidence: 99%

Experimental study of transitional behavior of fully developed under-ventilated compartment fire and associated facade flame height evolution

Ren,

Hu,

Zhang

et al. 2019

Combustion and Flame

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For compartment fires with an opening, two distinct states are widely recognized: wellventilated (oxygen is sufficient for combustion inside the compartment) and underventilated (oxygen is completely used inside the compartment). And as a consequence, the flame ejects out through the opening with excess fuel burning outside when reaching under-ventilated condition. However, in this work, a further transitional behavior of under-ventilated compartment fires with increasing fuel supply is revealed and quantified. Experiments were carried out using an under-ventilated fire compartment (0.4 m cubic) with a fixed opening width (0.25 m) and various opening heights (0.0125 m to 0.15 m) (corresponding ventilation factors, , 3.49×10-4 to 1.45×10-2 m2.5). The temperature inside the compartment and the facade flame ejected through the opening were recorded with increasing fuel supply (or namely total heat release rate) for under-ventilated conditions. The results showed that when the under-ventilated compartment fire reached a transitional state, the temperature inside the compartment experienced a sudden drop associated with a sudden increase of facade flame height outside the opening, posing a more severe impact on the building facade. The critical fuel supply rate for reaching the transitional state could be divided into two different mechanisms by a critical value of the opening ventilation factor (kg/s), based on the mass balance and flame stoichiometric extinction analysis inside the compartment. The formula for describing the critical fuel supply rate by considering the evolution of the critical air-fuel equivalence ratio () for both mechanisms was proposed. The classic model on the facade flame height for common under-ventilated compartment fires was found to be not applicable when the transitional state of underventilated condition had been reached. A new model was proposed to correlate the facade flame height for the transitional state of under-ventilated condition, which was shown to have a 2/3 power dependence on the total heat release rate taking the opening width as the characteristic length.

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“…Figures 6 and 7 support the above-mentioned statements. For ARR=8 h -1 , oxygen depletion and smoke filling are responsible for extinction, with an oxygen mole fraction in the lower part of the FE corner that drops down to 15.2%, which is very close to the limiting oxygen concentration for heptane (about 14% in Loo et al, 2013) (Fig. 6).…”

Section: Influence Of Renewal Ratementioning

confidence: 55%

Experimental study on low-frequency oscillating behavior in mechanically-ventilated compartment fires

Mense¹,

Pizzo

Pretrel³

et al. 2019

JAFM

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This study focuses on fire behavior in a mechanically-ventilated compartment, with a special emphasis on the low-frequency (LF) oscillatory behavior that has been occasionally observed. LF oscillations, typically in the order of a few mHz, can lead to large thermodynamic pressure variations, which in turn can cause fire safety issues (e.g. loss of confinement, mechanical damages). To address these issues, small-scale experiments are conducted varying the air renewal rate (ARR) in the compartment from 8 to 20 h-1 and the ventilation configuration. The fire source consists of heptane fuel loaded in a pan with a diameter of 18 cm. Depending on the ARR, LF oscillations are observed on the time evolution of the burning rate, and thus of all the other variables, with a frequency in the range of 16-26 mHz. As the ARR increases, there are three distinct regimes of burning behavior observed in this study: (1) rapid extinction due to smoke filling; (2) LF oscillating burning, followed by blow-off extinction after a few oscillations; and (3) LF oscillating burning, where extinction occurs because of the burning rate "runaway" due to an intensification of the heat transfer through the rim of the container. The oscillatory behavior and fire extinction result from the competition between oxygen supply and fuel vapor supply due to the heat feedback to the fuel tray. Both regimes (2) and (3) are accompanied by displacements of the flame out of the pan towards regions where oxygen is present. The influence of ARR and ventilation configuration (i.e. air inlet location and blowing direction) on the burning rate and LF oscillation properties (frequency, amplitude) is examined and discussed.

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Flame Extinction in a Ventilation-controlled Compartment

Cited by 14 publications

References 12 publications

Effect of Oxygen on the Burning Behavior of Liquid and Solid Fuels in a Large-Scale Calorimeter

Effect of Oxygen on the Burning Behavior of Liquid and Solid Fuels in a Large-Scale Calorimeter

Experimental study of transitional behavior of fully developed under-ventilated compartment fire and associated facade flame height evolution

Experimental study on low-frequency oscillating behavior in mechanically-ventilated compartment fires

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