Multi-parameter diagnostics for high-resolution in-situ measurements of single coal particle combustion

Köser, Jan; Li, Tao; Vorobiev, Nikita; Dreizler, Andreas; Schiemann, Martin; Böhm, Benjamin

doi:10.1016/j.proci.2018.05.116

Cited by 43 publications

(39 citation statements)

References 19 publications

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“…In the present work, the analysis focuses on the Air-condition with an oxygen concentration of 20 vol%. The measured gas temperature was about 1800 K directly downstream of the premixed flame and showed minor variation in different operating conditions, as reported by Köser et al (2019). Particles were injected through the central tube supported by the carrier gas with the same mixture as the flat flame inlet.…”

Section: Experimetal Methodologymentioning

confidence: 60%

“…The ignition delay time was defined as the first time when R exceeds 0.8 indicating strong correlations. The method was validated against the algorithm proposed in Köser et al (2019) and showed consistent results. A high-speed diffusive backlight-imaging (DBI) system was employed to measure the in-situ particle diameter and velocity.…”

Section: Experimetal Methodologymentioning

confidence: 79%

“…1a. The reactor is the same as that described in details by Köser et al (2019). It is composed of a particle seeder with a 0.8-mm injection tube, a ceramic honeycomb ( ∼ 80 × 80 mm 2 ) and fused silica chimney enclosure.…”

Section: Experimetal Methodologymentioning

confidence: 99%

“…(3) swell = m log(Ṫ) + b − 1 chemical reactivity in this region, caused by proper mixing and high temperature. The ignition location is affected by non-isotropic pyrolysis processes during particle heatup and the particle motion (slip and rotation) (Köser et al 2019). In the subsequent frames, the particle is enclosed by a spherical flame, whereas some inhomogeneity of OH spatial distribution still exists.…”

Section: Overall Analysis Of the Ignition Process And Volatile Combusmentioning

confidence: 99%

“…In the present study, the ignition of solid particles is analyzed comparing detailed experimental measurements Köser et al (2019) of the spatial distribution of OH around the particles with highly resolved numerical simulation employing the Chemical Percolation Devolatilization (CPD), finite rate chemistry, and a Lagrangian point-particle approach for the dispersed phase. In particular, experimental measurements provide time resolved data for the evolution of the particle velocity, size, and finally ignition delay time for a large number of conditions and initial particle sizes.…”

Section: Introductionmentioning

confidence: 99%

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Numerical Simulations and Experiments of Ignition of Solid Particles in a Laminar Burner: Effects of Slip Velocity and Particle Swelling

Attili

Farmand

Schumann

et al. 2020

Flow Turbulence Combust

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Ignition and combustion of pulverized solid fuel is investigated in a laminar burner. The two-dimensional OH radical field is measured in the experiments, providing information on the first onset of ignition and a detailed characterization of the flame structure for the single particle. In addition, particle velocity and diameter are tracked in time in the experiments. Simulations are carried out with a Lagrangian point-particle approach fully coupled with an Eulerian solver for the gas-phase, which includes detailed chemistry and transport. The numerical simulation results are compared with the experimental measurements in order to investigate the ignition characteristics. The effect of the slip velocity, i.e. the initial velocity difference between the gas-phase and the particle, is investigated numerically. For increasing slip velocity, the ignition delay time decreases. For large slip velocities, the decrease in ignition delay time is found to saturate to a value which is about 40% smaller than the ignition delay time at zero slip velocity. Performing a simulation neglecting the dependency of the Nusselt number on the slip velocity, it is found that this dependency does not play a role. On the contrary, it is found that the decrease of ignition delay time induced by the slip velocity is due to modifications of the temperature field around the particle. In particular, the low-temperature fluid related to the energy sink due to particle heating is transported away from the particle position when the slip velocity is non-zero; therefore, the particle is exposed to larger temperatures. Finally, the effect of particle swell is investigated using a model for the particle swelling based on the CPD framework. With this model, we observed negligible differences in ignition delay time compared to the case in which swelling is not included. This is related to the negligible swelling predicted by this model before ignition. However, this is inconsistent with the experimental measurements of particle diameter, showing a significant increase of diameter even before ignition. In further simulations, the measured swelling was directly prescribed, using an analytical fit at the given conditions. With this approach, it is found that the inclusion of swelling reduces the ignition delay time by about 20% for small particles while it is negligible for large particles.

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Section: Experimetal Methodologymentioning

confidence: 60%

Section: Experimetal Methodologymentioning

confidence: 79%

Section: Experimetal Methodologymentioning

confidence: 99%

Section: Overall Analysis Of the Ignition Process And Volatile Combusmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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