Temperature Measurement of Glowing Embers with Color Pyrometry

Urban, James L.; Vicariotto, Michela; Dunn‐Rankin, Derek; Fernandez‐Pello, A. C.

doi:10.1007/s10694-018-0810-3

Cited by 26 publications

(13 citation statements)

References 22 publications

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“…While averaged temperatures for the inner TSCs for the large pile reach about 700 • C, the temperatures of individual TSCs reached well over 900 • C instantaneously at higher wind speeds. These temperatures correspond well with previously measured temperatures by Urban et al (2019) using color pyrometry.…”

Section: Temperature Resultssupporting

confidence: 90%

Critical Ignition Conditions of Wood by Cylindrical Firebrands

2021

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This study investigated the thermal conditions preceding ignition of three dense woody fuels often found on structures by firebrands, a major cause of home ignition during wildland-urban interface (WUI) fires. Piles of smoldering cylindrical firebrands, fabricated from wooden dowels, were deposited either on a flat inert surface instrumented with temperature and heat flux sensors or on a target fuel (marine-grade plywood, oriented-strand board, or cedar shingles) to investigate critical conditions at ignition. The former provided thermal data to characterize the time before and at ignition, while the latter provided smoldering and flaming ignition times. Tests were conducted in a small-scale wind tunnel. Larger firebrand piles produced higher temperatures at the center of the pile, thought to be due to re-radiation within the pile. Ignition was found to be dependent on target fuel density; flaming ignition was additionally found to be dependent on wind speed. Higher wind speeds increased the rate of oxidation and led to higher temperatures and heat fluxes measured on the test surface. The heat flux at ignition was determined by combining results of inert and ignition tests, showing that ignition occurred while transient heating from the firebrand pile was increasing. Ultimately, critical ignition conditions from firebrand pile exposure are needed to design appropriate fire safety standards and WUI fire modeling.

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Section: Temperature Resultssupporting

confidence: 90%

Critical Ignition Conditions of Wood by Cylindrical Firebrands

2021

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“…The primary optimisation to reduce cost and scale would be to substitute the infrared camera with a modified consumer grade camera. Since it has been demonstrated that accurate measurement of a falling, rotating particle's temperature is complicated by the variability in orientation and actual temperature and the relatively low time in the field of view, a bespoke calibration is likely to be required so high resolution optical pyrometry is not required and alternative techniques may be appropriate [23]. Reducing the thermal information to this level would allow for significant cost reduction while only introducing the need for a laboratory calibration to determine the appropriate thresholds to distinguish between hot and cold firebrands.…”

Section: Reduction Of Scale and Costmentioning

confidence: 99%

Development of a Field Deployable Firebrand Flux and Condition Measurement System

et al. 2020

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A new instrument to quantify firebrand dynamics during fires with particular focus on those associated with the Wildland-Urban Interface (WUI) has been developed. During WUI fires, firebrands can ignite spot fires, which can rapidly increase the rate of spread (ROS) of the fire, provide a mechanism by which the fire can pass over firebreaks and are the leading cause of structure ignitions. Despite this key role in driving wildfire dynamics and hazards, difficulties in collecting firebrands in the field and preserving their physical condition (e.g. dimensions and temperature) have limited the development of knowledge of firebrand dynamics. In this work we present a new, field-deployable diagnostic tool, an emberometer, designed to provide measurement of firebrand fluxes and information on both the geometry and the thermal conditions of firebrands immediately before deposition by combining a visual and infrared camera. A series of laboratory experiments were conducted to calibrate and validate the developed imaging techniques. The emberometer was then deployed in the field to explore firebrand fluxes and particle conditions for a range of fire intensities in natural pine forest environments. In addition to firebrand particle characterization, field observations with the emberometer enabled detailed time history of deposition (i.e. firebrand flux) relative to concurrent in situ fire behaviour observations. We highlight that deposition was characterised by intense, short duration “showers” that can be reasonably associated to spikes in the average fire line intensity. The results presented illustrate the potential use of an emberometer in studying firebrand and spot fire dynamics.

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“…It is believed that the increased wind speed rather changes the combustion dynamics of the firebrands by providing more oxygen and therefore alters their temperatures, resulting in enhanced combustion reactions. There is limited knowledge on the firebrand temperature or heat of combustion of a firebrand [32][33][34]. Manzello et al [32] quantitatively showed that glowing firebrand surface temperature increased as the wind speed was increased.…”

Section: Resultsmentioning

confidence: 99%

Investigating Coupled Effect of Radiative Heat Flux and Firebrand Showers on Ignition of Fuel Beds

Suzuki

Manzello

2020

Fire Technol

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Fire spread occurs via radiation, flame contact, and firebrands. While firebrand showers are known to be a cause of spot fires which ignite fuels far from the main fire front, in the case of short distance spot fires, radiation from the main fire may play a role for firebrand induced ignition processes. Many past investigations have focused on singular effects on fire spread, and little is known about coupled effects. The coupled effect of radiative heat flux and firebrand showers on ignition processes of fuel beds is studied by using a newly developed experimental protocol. The newly developed protocol includes the addition of a radiant panel to the existing experimental setup of a firebrand generator coupled to a wind facility. Experiments were performed under an applied wind field, as the wind is a key parameter in large outdoor fire spread processes. Results show that radiant heat flux plays an important role for ignition by firebrands under 6 m/s while little effect was observed under 8 m/ s.

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Temperature Measurement of Glowing Embers with Color Pyrometry

Cited by 26 publications

References 22 publications

Critical Ignition Conditions of Wood by Cylindrical Firebrands

Critical Ignition Conditions of Wood by Cylindrical Firebrands

Development of a Field Deployable Firebrand Flux and Condition Measurement System

Investigating Coupled Effect of Radiative Heat Flux and Firebrand Showers on Ignition of Fuel Beds

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