An ignition criterion for combustible solids integrating surface temperature and heating rate

Tian, Ning; Zhou, Aixi

doi:10.1002/fam.2237

Cited by 3 publications

(6 citation statements)

References 27 publications

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“…For the ignition criterion, it is a common practice to assume an ignition temperature (T ig ), that is, flaming ignition will occur when the fuel surface temperature reaches a critical value (Quintiere, 2006), and such critical temperature is also most useful to predict the rate of fire spread (Atreya, 1998;Tian and Zhou, 2015). If the irradiation is below the critical value (q ′′ crt ), an equilibrium between radiant heating and environmental cooling will be reached at a surface temperature below T ig .…”

Section: Ignition Temperaturementioning

confidence: 99%

Piloted Ignition of Cylindrical Wildland Fuels Under Irradiation

et al. 2019

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Recent mega wildfires have become one of the most dangerous and devastating hazards, with a wide range of negative impacts on the economy, society, and environment. As cylindrical shrubs and twigs are typical fuel loads in wildfires, it is important to understand how the diameter and arrangement of cylindrical fuels affect their ignition behaviors. In this work, the piloted ignition of cylindrical wood rods with different diameters (3.2 ∼15.9 mm) are conducted under the irradiation up to 50 kW/m 2 . Three fuel groups are tested: (I) single vertical rod, (II) single horizontal rod, and (III) horizontal rod bed attached to the ground. For a single vertical rod, the measured ignition time decreases as the diameter is decreased from 15.9 to 6.4 mm, showing a thermally-thin behavior. However, the ignition of the 3.2-mm rod is more difficult than the 9.5-mm rod, because of the enhanced convective cooling by the larger curvature. Nevertheless, when the rod fuels are placed horizontally on the ground, the curvature-enhanced convective cooling becomes limited. For a single rod, when both the fuel diameter and the irradiation are small, only smoldering ignition occurs, and eventually the sample collapses. For the rod bed, flaming ignition always occurs, and it is easier to ignite because of a smaller convective cooling. For both horizontal configurations, the fuel ignition temperature increases almost linearly with the diameter from 270 • C (3.2 mm) to 330 • C (15.9 mm) but is insensitive to the irradiation level. This research quantifies the effect of fuel diameter and arrangement on the piloted ignition and reveals that the traditional classification of thermally thin and thick fuel for flat materials may not be suitable for cylindrical wildland fuels.

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Section: Ignition Temperaturementioning

confidence: 99%

Piloted Ignition of Cylindrical Wildland Fuels Under Irradiation

et al. 2019

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“…For a given material,

T_{i g}^{i n f}

T_{i g}^{c}

S T I R_{i g}^{c}

, and β are only the functions of surrounding environmental conditions (such as air flow spread, oxygen contraction, air pressure, and others) .…”

Section: Ignition Prediction Modelmentioning

confidence: 99%

“…For ease of understanding, they are briefly introduced in this section. More details about the HRIT criterion and the GTT model can be found in .…”

Section: Ignition Prediction Modelmentioning

confidence: 99%

“…The HRIT criterion is a new ignition criterion to address the experimental observation that a solid's surface temperature at ignition varies with external heat flux levels . For ignition to occur, HRIT criterion requires both surface temperature T surf and its increasing rate STIR to satisfy Equation .…”

Section: Ignition Prediction Modelmentioning

confidence: 99%

“…With these considerations, the heating rate‐related ignition temperature (HRIT) criterion combined with the general thermal thickness (GTT) heat transfer model was chosen as the ignition prediction model for SU analysis. The HRIT criterion can include the effect of the external heat fluxes that cannot be handled by other existing ignition criteria, such as critical surface temperature ( T ig ) [] and critical mass flux []. The analytical GTT can handle a solid material with any thickness .…”

Section: Introductionmentioning

confidence: 99%

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Sensitivity and uncertainty analyses for ignition of fiber‐reinforced polymer panels

Tian

Zhou

2015

Fire and Materials

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Summary The ignition characteristics of combustible solids are affected by many factors such as material properties, external heating source, and surrounding environmental conditions. In practice, these factors can vary significantly from one application to another. Thus, it is important to evaluate the sensitivity and uncertainty aspects of the effect of these factors on ignition. This study attempts to achieve this goal through sensitivity and uncertainty analyses on the piloted ignition of fiber‐reinforced polymer (FRP) composite panels. A Monte Carlo simulation using the Latin hypercube sampling method was employed to conduct sensitivity and uncertainty analyses. An integral model combining a general thermal thickness model with a heating rate‐related ignition temperature criterion was used as the ignition prediction model. Time‐to‐ignition was evaluated as the output parameter against the variations of input parameters such as material properties, external heating source, and surrounding environmental conditions. In addition, to identifying important sensitivity factors and uncertainty ranges of piloted ignition, a critical thermal thickness was found for the composite panels. These findings can serve as guides for the fire safety design of FRP composite materials for various applications. Copyright © 2015 John Wiley & Sons, Ltd.

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