Journal
COMBUSTION AND FLAME
Volume 233, Issue -, Pages -Publisher
ELSEVIER SCIENCE INC
DOI: 10.1016/j.combustflame.2021.111568
Keywords
Hyperspectral imaging technique; Single coal particle combustion; Soot volume fraction image; Emissivity of single coal particle
Categories
Funding
- National Natural Science Foundation of China [51776078, 51676077, 51827808]
- Fundamental Research Funds for the Central Universities [2019kfyXKJC033]
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This study utilized hyperspectral imaging technique to observe the real-time combustion behaviors of single coal particles and investigated the distribution rules of soot temperature and concentration using spectral radiative intensity images. The results show that the temperature remained relatively stable during the oxidation of chars, while the spectral emissivity increased and then decreased with the oxidation process.
This paper proposes a hyperspectral imaging technique for capturing radiative images at a high temporal- spatial resolution, for the purpose of spectrally visualizing the instantaneous combustion behaviors of single coal particles. We initially use a hyperspectral imaging device to record the combustion processes of two types of single pulverized coal particles on a McKenna flat-flame burner. From the snapshot images captured by the device, we observe the combustion processes, ignition characteristics, flame morphologies, and sizes of the two single coal particles. The observations indicate that the two single coal particles undergo volatile release/combustion and char ignition/oxidation during the luminous combustion process; moreover, both particles exhibit homogeneous ignition characteristics under the experimental conditions. Furthermore, based on the spectral radiative intensity images obtained via the device, the soot temperature and volume fraction images of the two single coal particles in the envelope flame are obtained at different burning times. Thereafter, the influences of the combustion behaviors and soot formation mechanisms on the distribution rules of the soot temperature and concentration at different combustion periods are discussed. Finally, the temperature and apparent spectral emissivity values of the two single char particles during the char oxidation process are also calculated to analyze their combustion behaviors. The results show that the temperature changes within a relatively narrow range with respect to the burning time during the oxidation stage, whereas the spectral emissivity continues to increase with the oxidation of chars and subsequently decreases. (c) 2021 The Combustion Institute. Published by Elsevier Inc. All rights reserved.
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