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Evaluation of Planck mean coefficients for particle radiative properties in combustion environments

Hofgren, Henrik LU and Sundén, Bengt LU (2015) In Heat and Mass Transfer 51(4). p.507-519
Abstract
Thermal radiation is the dominating form of heat transfer in several combustion technologies that combust solid fuels, such as pulverized coal combustion and fixed bed combustion. The thermal radiation originates from the hot combustion gases and particles. For accurate modelling of thermal radiation in these environments the selection of the radiative transport model and radiative property model is important. Radiative property models for gases have received huge attention and several well documented models exist. For particles, soot has received considerable attention whereas other particles have not to a similar extent. The Planck mean coefficients are most commonly used to describe the radiative properties of the particles. For gases... (More)
Thermal radiation is the dominating form of heat transfer in several combustion technologies that combust solid fuels, such as pulverized coal combustion and fixed bed combustion. The thermal radiation originates from the hot combustion gases and particles. For accurate modelling of thermal radiation in these environments the selection of the radiative transport model and radiative property model is important. Radiative property models for gases have received huge attention and several well documented models exist. For particles, soot has received considerable attention whereas other particles have not to a similar extent. The Planck mean coefficients are most commonly used to describe the radiative properties of the particles. For gases the Planck mean absorption coefficient is known to give large deviations from recognised exact models in predicting the radiative heat transfer. In this study the use of Planck mean coefficients for particles are investigated and compared to spectral models. Two particle mass size distributions of fly ash are used, representing biomass and coal combustion. The evaluation is conducted in several combustion-like test cases with both gases and particles. The evaluation shows that using Planck mean coefficients for particles, in combustion-like situations, can give large errors in predicting the radiative heat flux and especially the source term. A new weighted sum of grey gas approach is tested and evaluated. It includes both the particles and gases to better account for the non-greyness of the fly ash absorption coefficient. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Heat and Mass Transfer
volume
51
issue
4
pages
507 - 519
publisher
Springer
external identifiers
  • wos:000353214900006
  • scopus:84924765440
ISSN
1432-1181
DOI
10.1007/s00231-014-1431-0
language
English
LU publication?
yes
id
687763ff-6688-44e8-9880-2b848c1adf6b (old id 5281910)
date added to LUP
2015-04-24 12:45:42
date last changed
2017-09-24 03:22:32
@article{687763ff-6688-44e8-9880-2b848c1adf6b,
  abstract     = {Thermal radiation is the dominating form of heat transfer in several combustion technologies that combust solid fuels, such as pulverized coal combustion and fixed bed combustion. The thermal radiation originates from the hot combustion gases and particles. For accurate modelling of thermal radiation in these environments the selection of the radiative transport model and radiative property model is important. Radiative property models for gases have received huge attention and several well documented models exist. For particles, soot has received considerable attention whereas other particles have not to a similar extent. The Planck mean coefficients are most commonly used to describe the radiative properties of the particles. For gases the Planck mean absorption coefficient is known to give large deviations from recognised exact models in predicting the radiative heat transfer. In this study the use of Planck mean coefficients for particles are investigated and compared to spectral models. Two particle mass size distributions of fly ash are used, representing biomass and coal combustion. The evaluation is conducted in several combustion-like test cases with both gases and particles. The evaluation shows that using Planck mean coefficients for particles, in combustion-like situations, can give large errors in predicting the radiative heat flux and especially the source term. A new weighted sum of grey gas approach is tested and evaluated. It includes both the particles and gases to better account for the non-greyness of the fly ash absorption coefficient.},
  author       = {Hofgren, Henrik and Sundén, Bengt},
  issn         = {1432-1181},
  language     = {eng},
  number       = {4},
  pages        = {507--519},
  publisher    = {Springer},
  series       = {Heat and Mass Transfer},
  title        = {Evaluation of Planck mean coefficients for particle radiative properties in combustion environments},
  url          = {http://dx.doi.org/10.1007/s00231-014-1431-0},
  volume       = {51},
  year         = {2015},
}