Account for variations in the H2O to CO2 molar ratio when modelling gaseous radiative heat transfer with the weighted-sum-of-grey-gases model

Johansson, Robert; Leckner, Bo G; Andersson, Klas; Johnsson, Filip

doi:10.1016/j.combustflame.2011.02.001

Cited by 210 publications

(131 citation statements)

References 31 publications

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“…In recent years, on the basis of the accumulated knowledge of the fundamental differences between airfuel and oxy-fuel combustion, much effort has been devoted to developing and validating sub-models for the new combustion environment. For instance, new approaches have been developed for heat transfer modelling in environments with high concentrations of CO 2 and H 2 O vapor, e.g., the Weighted-Sum-of-Gray-Gases-Model (WSGGM) refined for oxy-fuel combustion modelling [16,17]. Specific models for volatile combustion in CO 2 -rich environments [18] and for char combustion under oxyfuel conditions [19] have also been developed.…”

Section: Introductionmentioning

confidence: 99%

Biomass co-firing under oxy-fuel conditions: A computational fluid dynamics modelling study and experimental validation

Álvarez

Yin

Riaza

et al. 2014

Fuel Processing Technology

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This paper presents an experimental and numerical study on co-firing olive waste (0, 10%, 20% on mass basis) with two coals in an entrained flow reactor under three oxyfuel conditions (21%O 2 /79%CO 2 , 30%O 2 /70%CO 2 and 35%O 2 /65%CO 2 ) and air-fuel condition. Co-firing biomass with coal was found to have favorable synergy effects in all the cases: it significantly improves the burnout while remarkably lowers NO x emissions. The reduced peak temperatures during co-firing can also help to mitigate deposition formation in real furnaces. Co-firing CO 2 -neutral biomass with coals under oxy-fuel conditions can achieve a below-zero CO 2 emission if the released CO 2 is captured and sequestered. The model-predicted burnout and gaseous emissions were compared against the experimental results. A very good agreement was observed, the differences in a range of ±5-10% of the experimental values, which indicates the model can be used to aid in design and optimization of large-scale biomass co-firing under oxy-fuel conditions.

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Section: Introductionmentioning

confidence: 99%

Biomass co-firing under oxy-fuel conditions: A computational fluid dynamics modelling study and experimental validation

Álvarez

Yin

Riaza

et al. 2014

Fuel Processing Technology

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“…The weighting function is normally fitted by a polynomial function dependent on temperature. This work uses the same method as [24,26] by normalizing the fitting coefficients with a reference temperature, T ref at 1,200 K, as…”

Section: Weighted Sum Of Grey Gas Model Calculationsmentioning

confidence: 99%

“…The desired Planck mean coefficient can therefore be taken from the base case, Table 1, and then multiplied by the ratio between the actual load and the base case load. For the WSGG including particles the same method as used in [24,26] for variable molar ratios for H 2 O to CO 2 was applied for variable particle loads. With 6.5 g/Nm 3 being the base case, load = 1, six other sets of coefficients were produced for the coal and biomass ash particles at [0.1, 0.25, 0.75, 1.5, 2.0] times the base load.…”

Section: Weighted Sum Of Grey Gas Model Calculationsmentioning

confidence: 99%

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

Hofgren

Sundén

2014

Heat Mass Transfer

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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.

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“…Taking into account that a limitation of the WSGG is that its correlations coefficients are generally established for a particular ratio of partial pressures for CO 2 and H 2 O mixtures, Krishnamoorthy [12] obtained new WSGG parameters computed from total emissivity correlations encompassing the range of the H 2 O/CO 2 ratios encountered within Sandia Flame D. With the same motivation, Johansson et al [13] modified the WSGG to account for various ratios of H 2 O and CO 2 concentrations, covering from oxyfuel combustion of coal to combustion of natural gas.…”

Section: Introductionmentioning

confidence: 99%

Numerical simulations of the radiative transfer in a 2D axisymmetric turbulent non-premixed methane–air flame using up-to-date WSGG and gray-gas models

Centeno

Silva

Brittes

2015

J Braz. Soc. Mech. Sci. Eng.

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the computation of radiation with both the CR-WSGG and NCR-WSGG models provided better results than GG model, when compared with experimental data. For the combustion chamber and turbulence and combustion models employed in the present work, it was shown that the CR-WSGG is the recommended model, due to the acceptable agreement with experimental data and relatively low computational requirements in comparison to the NCR-WSGG model. The results show the importance of thermal radiation for an accurate prediction of the thermal behavior of a combustion chamber.

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Account for variations in the H2O to CO2 molar ratio when modelling gaseous radiative heat transfer with the weighted-sum-of-grey-gases model

Cited by 210 publications

References 31 publications

Biomass co-firing under oxy-fuel conditions: A computational fluid dynamics modelling study and experimental validation

Biomass co-firing under oxy-fuel conditions: A computational fluid dynamics modelling study and experimental validation

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

Numerical simulations of the radiative transfer in a 2D axisymmetric turbulent non-premixed methane–air flame using up-to-date WSGG and gray-gas models

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