Temperature and heat flux measurements from firebrand piles using color ratio pyrometryIgweh, Elijah Jerome (Korespondenčni avtor) Stoliarov I., Stanislav (Avtor) Sunderland, Peter B. (Avtor) firebrandsheat fluxcolor ratio pyrometrypyrometryimage processingGlowing 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.Elsevier20262026-07-17 09:13:09Neznano31164UDK: 614.84ISSN pri članku: 1873-7226DOI: 10.1016/j.firesaf.2026.104712COBISS_ID: 285142019sl© 2026 The Authors