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Quantification of the influence of parameters determining radiative heat transfer in an oxy-fuel operated boiler

Gronarz, Tim and Schulze, Jan and Laemmerhold, Mischka and Graeser, Philipp and Gorewoda, Jeanette and Kez, Vitali and Habermehl, Martin and Schiemann, Martin and Ströhle, Jochen and Epple, Bernd and Scherer, Viktor and Kneer, Reinhold (2017):
Quantification of the influence of parameters determining radiative heat transfer in an oxy-fuel operated boiler.
In: Fuel Processing Technology, pp. 76-89, 157, ISSN 03783820, DOI: 10.1016/j.fuproc.2016.11.012, [Online-Edition: https://doi.org/10.1016/j.fuproc.2016.11.012],
[Article]

Abstract

Radiative heat transfer is a very important heat transfer mechanism in pulverized coal combustion. To identify the influence of parameters determining radiatve heat transfer and to give recommendations on the required accuracy of corresponding submodels, a 3D-periodic oxy-fuel pulverized coal combustion test case is investigated. Measurement values determined by the authors or elaborate submodels are applied for each parameter and compared to simplified models or empirical constants. To investigate the interaction between particle radiation and the strong spectral dependence of gas radiation in oxy-fuel scenarios, a comparison between spectrally averaged and spectrally resolved calculations performed. To the best knowledge of the authors, for the first time the contribution of the parameters determining radiative heat transfer are quantified and compared in one comprehensive study.

The results indicate a strong influence of coal particle emissivity and scattering phase function as well as the projected particle surface on the radiative source term. For the wall heat flux, the largest influences were found for ash and coal particle emissivity, projected particle surface and the scattering phase function. Additionally, the difference between coal particle and gas temperature was found to have a significant influence on wall heat flux. A comparison of spectrally averaged to spectrally resolved results and the corresponding models for gas radiation (WSGGM and SNBM) yielded similar trends for the influence of each parameter. Thus, based on the models and parameters involved in this study, a spectrally averaged approach seems to be of sufficient accuracy to describe radiative heat transfer in oxy-fuel combustion systems.

Item Type: Article
Erschienen: 2017
Creators: Gronarz, Tim and Schulze, Jan and Laemmerhold, Mischka and Graeser, Philipp and Gorewoda, Jeanette and Kez, Vitali and Habermehl, Martin and Schiemann, Martin and Ströhle, Jochen and Epple, Bernd and Scherer, Viktor and Kneer, Reinhold
Title: Quantification of the influence of parameters determining radiative heat transfer in an oxy-fuel operated boiler
Language: English
Abstract:

Radiative heat transfer is a very important heat transfer mechanism in pulverized coal combustion. To identify the influence of parameters determining radiatve heat transfer and to give recommendations on the required accuracy of corresponding submodels, a 3D-periodic oxy-fuel pulverized coal combustion test case is investigated. Measurement values determined by the authors or elaborate submodels are applied for each parameter and compared to simplified models or empirical constants. To investigate the interaction between particle radiation and the strong spectral dependence of gas radiation in oxy-fuel scenarios, a comparison between spectrally averaged and spectrally resolved calculations performed. To the best knowledge of the authors, for the first time the contribution of the parameters determining radiative heat transfer are quantified and compared in one comprehensive study.

The results indicate a strong influence of coal particle emissivity and scattering phase function as well as the projected particle surface on the radiative source term. For the wall heat flux, the largest influences were found for ash and coal particle emissivity, projected particle surface and the scattering phase function. Additionally, the difference between coal particle and gas temperature was found to have a significant influence on wall heat flux. A comparison of spectrally averaged to spectrally resolved results and the corresponding models for gas radiation (WSGGM and SNBM) yielded similar trends for the influence of each parameter. Thus, based on the models and parameters involved in this study, a spectrally averaged approach seems to be of sufficient accuracy to describe radiative heat transfer in oxy-fuel combustion systems.

Journal or Publication Title: Fuel Processing Technology
Volume: 157
Uncontrolled Keywords: Sensitivity analysis, Radiative transfer, Coal combustion, Absorption, Emissivity, Scattering phase function, Particle radiation
Divisions: 16 Department of Mechanical Engineering
16 Department of Mechanical Engineering > Institut für Energiesysteme und Energietechnik (EST)
Profile Areas
Profile Areas > Thermo-Fluids & Interfaces
Date Deposited: 02 Apr 2019 14:16
DOI: 10.1016/j.fuproc.2016.11.012
Official URL: https://doi.org/10.1016/j.fuproc.2016.11.012
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