20.500.12556/DiRROS-31164 Temperature and heat flux measurements from firebrand piles using color ratio pyrometry Glowing firebrands are a key ignition source in Wildland–Urban Interface fires, yet their thermal characterization is challenging due to small size, irregular shape and sensitivity to environmental conditions. This study extends color ratio pyrometry from a single firebrand to firebrand piles to measure spatially resolved surface temperatures, heat flux to a remote location, and radiative loss fraction in a wind tunnel at 0.9–2.7 m/s. A Digital Single Lens Reflex camera, calibrated against a blackbody furnace, recorded temperatures at 1 Hz in the range 873–1473 K. Mean surface temperatures were measured with color ratio pyrometry and determined to be 1130–1260 K, with localized hot spots on the windward side of the pile. Radiant heat flux at a point 9.6 cm above the firebrand pile was computed using a pixel-wise view factor method with surface-specific emissivity and transmittance. This approach reproduced the temporal trends measured by a Schmidt–Boelter heat flux gauge, with peaks near 6 kW/m2. Including a correction for hot, non-glowing regions below 873 K improved agreement across all wind speeds, keeping the average error below 9%. The radiative loss fraction, measured via carbon oxide calorimetry, stabilized at 0.20–0.23 during the first 100 s of the glowing phase. firebrands heat flux color ratio pyrometry pyrometry image processing ognjeni žganci toplotni tok barvno razmerje pirometrija obdelava slik true false true Elsevier Angleški jezik Slovenski jezik © 2026 The Authors Neznano 2026-07-17 09:13:09 2026-07-17 09:19:52 2026-07-18 03:45:03 0000-00-00 00:00:00 2026 0 0 This article is part of a Special issue entitled: ‘FISJ_IAFSS 2026’ published in Fire Safety Journal. str. 1-10 [article no.] 104712 Vol. 162 Jul. 2026 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 2026-03-19 614.84 1873-7226 10.1016/j.firesaf.2026.104712 285142019 https://doi.org/10.1016/j.firesaf.2026.104712 0 f8079080-81ae-11f1-b863-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=48068 RAZ_Stoliarov_I._Stanislav_2026.pdf RAZ_Stoliarov_I._Stanislav_2026.pdf 1 A2C69BA8D4B83E2789B50D70E37DC616 1e593a65865f6f2fff35dc90d1e0fc3d673b15d0aa1818a5eca2fb0e0e6969da df6159c4-81af-11f1-b863-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=48069 Zavod za gradbeništvo Slovenije 0 0 0