A novel mathematical framework for estimating the temperature of condensed emitters in hybrid aluminum-gas flames using emission spectroscopy

• Rigorous math model for spectroscopy-based temperature of condensed emitters in Al dust flames. • Single-signal discrimination of Al ( ̴ 2400 K) and Al 2 O 3 ( ̴ 3300 K) temperatures in hybrid flame. • Radial temperature profiles reveal Al concentration-dependent flame structures. Accurate temperature measurement in metal dust flames, particularly aluminum-based flames, is essential for understanding combustion behavior and refining simulations. Traditional methods often fail in these complex environments, making emission spectroscopy the preferred approach. However, aluminum and aluminum-gas hybrid flames present challenges due to their complex structure, which complicates the interpretation of emission signals using standard models. This study focuses on an aluminum-methane-oxygen-argon hybrid flame, chosen for its stability and broad applicability. The research introduces a mathematical method to calculate the temperatures of condensed emitters, specifically, micrometric aluminum particles and nanometric alumina particles, by accounting for overlapping continuous emission fluxes from the flame’s layered structure. Using a high-sensitivity spectrometer (1.2 nm resolution) and combined with precise displacement system, spatially resolved emission spectra were collected from a stabilized Bunsen-type flame. Flame radiation is modelled by superposing the contributions of multiple condensed emitters, each following Planck’s law. The temperature is determined by fitting this model to experimental data. For a dust concentration of 135 ± 15 g/m3, aluminum particles reached 2037 K near the flame and stabilized at around 2400 K, while alumina temperatures rose from 2693 K to 3316 K, indicating delayed oxidation in oxygen-rich zones. These values align with theoretical predictions, remaining below aluminum’s vaporization point but near alumina’s melting point. At 80 ± 20 g/m3, temperatures for aluminum (2400 K) and alumina (3350 K) showed small variation. The findings provide insights into particle combustion regimes in dust flames, advancing both experimental and modeling approaches for metal combustion systems.