Experimental and numerical analysis of turbulent pulverized coal flame in a coaxial burner

Numerical Analysis of a Turbulent Pulverized Coal Flame Using a Flamelet/Progress Variable Approach and Modeling Experimental Artifacts

“…A first simulation was conducted by Ahn et al, who obtained much better results in terms of the temperature (likely as a result of the thermocouple measurement). 21 However, the species prediction still showed some notable deviations from the experiments. This may have been related to spatial averaging effects occurring in the gas sampling experiments, which will be an object of study in the present work.…”

“…The final modeled volatile gas composition consists of N 2 , H 2 , CO, and C 2 H 4 . The particle size distribution was imposed stochastically, using a measured size distribution taken from Ahn et al 21 The reduced CRECK mechanism with 52 species and 452 reactions was considered to calculate the non-premixed flamelets. 41,42 The table dimensions are 263 × 11 × 11 × 101 in mixture fraction sum, mixture fraction ratio, normalized enthalpy, and normalized progress variable space, respectively.…”

“…The investigated flame has been developed by CRIEPI in Japan. 7,21−23 New experimental studies with a hydrogen-supported flame instead of the previous methane pilot flame have been performed by Ahn et al 21 The main jet with a diameter of 6 mm is fed with pulverized coal and air. A wall of 0.5 mm wall thickness separates the main jet from the annular hydrogen pilot stream, which has a channel width of 0.5 mm.…”

“…For a detailed explanation, the reader is referred to studies by Hwang, Ahn, and their respective co-workers. 7,21−23 The experimental data are taken from the proceedings of coal and biomass conversion (CBC) in 2019 49 and from the study by Ahn et al 21 The temperature was measured with a K-type sheathed thermocouple; particle velocities were measured by particle image velocimetry (PIV); and gas concentrations were obtained from a gas analyzer using a ceramic suction probe, inserted in the axial direction into the flame, which determines volume-averaged values over the sucked-in volume. 21 A more detailed description of the suction probe and an approach to consider the resulting volume-averaged data in the numerical evaluation are given in the Post-processing and Probe Correction section.…”

“…Recently, the experimentalists at CRIEPI have introduced a new test case, which uses hydrogen as pilot gas instead of methane and aims to minimize the relative heat input by the pilot to set a stronger focus on coal combustion. 21 For the new flame, the temperature was measured by thermocouples to provide more accurate data than the pyrometer in the original experiment. A first simulation was conducted by Ahn et al, who obtained much better results in terms of the temperature (likely as a result of the thermocouple measurement).…”