Nongray EWB and WSGG Radiation Modeling in Oxy-Fuel Environments

E. David Huckaby; Osama A. Marzouk

REVIEW 2 major objections 4 minor 14 references

Nongray EWB and WSGG Radiation Modeling in Oxy-Fuel Environments

T0 review · 2 major / 4 minor · reviewed 2026-08-12 · deepseek-v4-flash

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Pith's one-line read Air-fuel radiation models are not reliable for oxy-fuel furnace heat transfer, and oxy-fuel-specific models improve predictions without any single model winning outright.

desk verdict Solid practical comparison of six WSGG models against an approximate EWB benchmark; the air-fuel vs oxy-fuel conclusion is robust, but oxy-fuel rankings rest on an unvalidated reference. read the letter →

arxiv 2411.16753 v1 pith:AQHTJIAP submitted 2024-11-24 physics.gen-ph

Osama A. Marzouk , E. David Huckaby This is my paper · ORCID

classification physics.gen-ph

keywords oxy-fuelcombustionweighted-sum-of-gray-gasesmodelexponentialwidebandradiativeheattransfercarboncapturenongrayradiationfluegasrecycleWSGGevaluation

verification ladder T0 review T1 audit T2 compute T3 formal

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

This chapter tests whether radiation models tuned for air-fuel combustion can be carried over to oxy-fuel environments, where nitrogen is replaced by high concentrations of CO2 and H2O. It compares five oxy-fuel-weighted-sum-of-gray-gases models and one air-fuel WSGG model against a 22-block exponential-wide-band reference solution in two isothermal 1500 K enclosures, one with 65% CO2 and one with 90% CO2. The central finding is that the air-fuel model underpredicts area-integrated wall radiative heat transfer by 14.7% in the wet-recycle case and 29.3% in the dry-recycle case, which would lead to overpredicted gas temperatures. All five oxy-fuel WSGG models stay within 10.4% of the benchmark, but none is consistently superior, so model choice should match the operating regime of the target system.

What carries the argument

The benchmark is a box model based on the exponential wide band model, which idealizes the vibration-rotation and pure-rotation bands of H2O and CO2 into 22 spectral blocks with piecewise-constant absorption coefficients, using Edwards-Menard correlations for vibration-rotation bands and a Felske-Tien expression for the pure-rotation band, with a single mean beam length of 9.3913 m. The weighted-sum-of-gray-gases models solve 4 or 5 radiative transfer equations per direction, each gray gas having a constant absorption coefficient and a temperature-polynomial blackbody weight, with a clear gas for spectral windows. The comparison is carried out in a 12x12x40 m enclosure on a 59,778-cell mesh with 128 angular divisions, with the SLW method included as a second reference, and the radiative source term and wall heat flux are reported relative to the box/EWB solution.

What would settle it

Run a line-by-line radiative transfer calculation using a modern high-temperature spectral database for the same 12x12x40 m enclosures at 1500 K with compositions 65% CO2/35% H2O and 90% CO2/10% H2O, and compare the total wall radiative heat transfer to the box/EWB values of 224.74 MW and 190.54 MW; deviations of more than a few percent would shift every reported model error and could change the ranking of the WSGG models.

Watch

Extended reading notes

Core claim

The paper establishes that using an air-fuel WSGG model in oxy-fuel environments causes appreciable underprediction of both local and area-integrated radiative heat flux to the walls, and corresponding overprediction of temperatures because the radiative heat loss is underpredicted. The errors grow when the CO2 fraction rises: the air-fuel model underpredicts wall-center heat flux by 19.9% at 65% CO2 and by 33.9% at 90% CO2, and area-integrated wall heat transfer by 14.7% and 29.3% respectively. The oxy-fuel WSGG models, by contrast, overpredict area-integrated wall heat transfer by 0.62% to 10.39%, with no particular model clearly superior across both environments. The radiative flux to the wall is much more sensitive to gas composition than the radiative source term, making wall heat transfer the discriminating quantity.

Load-bearing premise

The entire error ranking assumes the 22-block box/EWB solution is the true answer, but that benchmark is itself a coarse idealization built from band correlations and a single mean beam length, with no line-by-line validation.

Editorial extensions

If this is right

Air-fuel WSGG models should not be used for oxy-fuel furnace radiation simulations, because they systematically underpredict wall heat loss and would bias temperature predictions high.
The air-fuel model's error grows with CO2 concentration, so dry-recycle oxy-fuel designs are at greater risk of incorrect radiative predictions than wet-recycle designs.
Oxy-fuel WSGG models provide acceptable engineering accuracy for area-integrated wall heat transfer, with all tested models within 10.4% of the box/EWB benchmark.
No single oxy-fuel WSGG model dominates, so practical model selection should weigh simplicity and whether the target composition and temperature lie within the model's training regime.
Wall radiative flux is a more composition-sensitive and therefore more discriminating test of radiation models than the centerline radiative source term.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

Beyond the paper's comparison, the box/EWB benchmark itself is an approximation built from band correlations and one mean beam length, so a line-by-line calculation with a modern high-temperature spectral database would be the natural next check on whether the reported error percentages and model rankings hold.
The same regime-matching lesson likely extends beyond radiation: other combustion submodels tuned for air-fuel flue gases may need re-evaluation when applied to oxy-fuel mixtures with high CO2 and H2O fractions.
In non-isothermal or sooty flames, where the clear-gas weight and spectral windows interact differently with temperature and particle radiation, the ranking among oxy-fuel WSGG models could differ from the ranking found in these isothermal gas-only enclosures.
The paper's finding that wall heat flux is strongly composition-sensitive suggests that oxy-fuel furnace design studies should report wall heat transfer, not only centerline temperatures, when validating radiation models.

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Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Desk Editor's Note

read the letter

Read it. The useful thing is the head-to-head tables: six WSGG models, two oxy-fuel gas compositions, same enclosure, same solver, with sensitivity checks on mesh and angular resolution. That is real work and it gives boiler modelers a practical error budget. The paper does not claim a new property model; it evaluates published ones, which is legitimate and overdue.

The main qualitative conclusion—air-fuel WSGG coefficients badly under-predict wall heat flux (14.7% and 29.3% area-integrated; about 80% at the source centroid) and would overpredict gas temperature—is well supported. The claim that no oxy-fuel WSGG model is clearly superior is also honestly stated and backed by tables where different models win on different metrics (5g cubic excellent on wall flux but poor on source; 4g quadratic best on source but 8.7% high on heat load).

Soft spots, in proportion. The reference solution is not LBL-validated. The box/EWB uses Edwards-Menard and Felske-Tien correlations, 22 blocks, and converts block emissivities to absorption coefficients with one global mean beam length L=9.39 m for a 40 m enclosure. Since band absorptance is nonlinear in path length, the single-L conversion can bias the near-wall short paths. The paper reports all errors relative to this EWB solution, and it never checks EWB against line-by-line or narrow-band data. For the gross air-fuel vs oxy-fuel gap, the errors are so large that the conclusion survives an EWB bias of several percent. But the finer claims—which oxy-fuel model is within 1% versus 5%, and the exact error rankings—are only as good as the EWB benchmark. The authors should either run one LBL/NB check or explicitly state the EWB uncertainty; without that, the percentage errors in Tables 3–8 are not anchored.

Also worth noting: the SLW comparison comes from older HITRAN-based ALBDF fits and a different angular method (T4 DOM vs FVM), so it is context, not a benchmark. Self-citation is present but fair—the interpolation method from their prior conference paper is applied to someone else's model, which is exactly what an evaluation should do. No code is released, which is a minor reproducibility ding for this kind of applied benchmarking.

Who this is for: engineers running CFD on oxy-fuel furnaces who need to choose among published WSGG models. It is a legitimate model-selection guide, not a fundamental advance. A serious referee should engage—the comparison is clean enough to be useful, and the missing EWB validation is fixable in revision.

Referee Report

2 major / 4 minor

Summary. The manuscript evaluates six weighted-sum-of-gray-gases models (five developed for oxy-fuel combustion and one for air-fuel) against an exponential wide band box-model benchmark for two isothermal, homogeneous enclosures representing wet and dry oxy-fuel flue-gas compositions. The radiative source, wall flux, and area-integrated wall heat transfer are compared, and percentage errors are tabulated. The authors conclude that the air-fuel WSGG model substantially underpredicts wall radiative heat transfer and would overpredict gas temperatures, while the oxy-fuel WSGG models all perform within about 10% of the benchmark with no single model clearly superior.

Significance. If the box/EWB benchmark is reliable, the paper provides a practically useful model-selection guide for oxy-fuel combustion CFD. It consolidates recently proposed oxy-fuel WSGG models, tabulates their coefficients and weights for the two studied compositions, and documents the numerical setup in detail. The paper also includes an explicit caution about the limitations of the SLW reference solution. The main weakness is that the benchmark itself is unvalidated, so the quantitative error percentages and fine distinctions among models must be treated with caution.

major comments (2)

[Section 2.1, Tables 9-10] The box/EWB benchmark is constructed by converting band emissivities to block absorption coefficients using a single global mean beam length L=3.6V/A=9.3913 m, as stated on p. 496. In the 12x12x40 m enclosure, radiation path lengths vary from near zero at the walls to about 40 m, and band absorptance is strongly nonlinear in path length. The paper provides no line-by-line or narrow-band validation of the resulting k_i for the two H2O/CO2 mixtures at 1500 K. Since every error percentage in Tables 3-8 is defined relative to this benchmark, a systematic bias in L would shift all quoted errors and could alter the ranking among oxy-fuel models, whose errors differ by only a few percent (e.g., 0.62% versus 10.39% in Table 8). Please add an explicit validation of the EWB emissivities against LBL or SNB data over a range of path lengths relevant to the enclosure, or a sensitivity analysis that perturbs the block k_i within plausible uncertainty and reassesses the model rankings.
[Section 2.1, p. 496] The use of a single mean beam length to derive k_i is particularly questionable for the wall radiative flux, because the near-wall paths that dominate the wall flux are much shorter than 9.39 m. The paper should demonstrate that the box/EWB wall flux is robust to the choice of L, for example by recomputing the benchmark with L/2 and 2L or with a path-length-resolved treatment, and should report how the oxy-fuel model rankings change. Without such a demonstration, the claim that 'no particular oxy-fuel model was clearly superior' is not yet established.

minor comments (4)

[Section 4.1] The grid and angular resolution sensitivity checks are reported only qualitatively as 'nearly identical.' Please provide the maximum relative differences in the quantities of interest (e.g., area-integrated wall heat transfer and radiative source) between the adopted and finer resolutions so readers can judge the numerical error level.
[Section 4.2] The SLW solution is included in the radiative-source comparisons (Tables 3-4) but is absent from the wall-flux and heat-transfer tables (Tables 5-8). If SLW results were not available for those quantities, this should be stated explicitly; otherwise the omission is puzzling.
[Equations (1)-(9)] The notation is inconsistent in places: for example, 'Ibtot' and 'Trot' appear in the rendered equations without clear subscripts. Please standardize the symbols for total blackbody intensity and total temperature in the final manuscript.
[Section 2.1 and Conclusions] The paper candidly acknowledges the limitations of the SLW reference (old HITRAN database, low-temperature fits) but does not provide an equally critical discussion of the EWB benchmark's approximations. A brief limitation statement about the box/EWB model in Section 2.1 or the Conclusions would improve balance.

Circularity Check

0 steps flagged · score 0.0 of 10

No significant circularity: the study evaluates externally parameterized WSGG models against an independent EWB benchmark; the sole self-citation is a minor implementation recommendation.

full rationale

This is an evaluation study, not a derivation. The five oxy-fuel WSGG models and the air-fuel model are taken from the literature with parameters fixed by their original authors (Table 1 lists training data: SNBM, empirical correlations, and EWBM). The paper fits none of these parameters and does not rename a known result in new coordinates. The benchmark box/EWB solution is constructed independently in Section 2.1 from Edwards-Menard and Felske-Tien band correlations and a specified mean beam length; the WSGG models are not fitted to this benchmark, so the error percentages in Tables 3-8 are comparisons against an external reference rather than reductions to the models' inputs. The self-citation to Marzouk and Huckaby [18] only recommends an interpolation technique for the continuous-parameter WSGG model; this is a minor implementation choice, not a load-bearing premise of the central air-fuel versus oxy-fuel conclusion, and the cited comparison is externally falsifiable. The possible approximation of the EWB reference (single mean beam length, no line-by-line check) is a correctness or robustness limitation, not a circularity, and does not make any prediction equivalent to its inputs by construction.

Assumptions & free parameters 9 free parameters · 6 assumptions · 0 invented entities

This paper introduces no new fitted parameters or invented entities. All free parameters listed are inherited from prior literature, and the central comparison depends on those inherited coefficients plus the EWB benchmark assumptions. The most honest measure of what the paper adds is the evaluation itself, not a new model.

free parameters (9)

EWB mean beam length = 9.3913 m
Set as 3.6V/A for the 12x12x40 m enclosure (Section 2.1); used to convert band emissivities into block absorption coefficients.
EWB band parameters = Edwards-Menard 3-regime and Felske-Tien expressions (refs [11]-[15])
Band equivalent width parameters for CO2/H2O vibration-rotation and H2O pure-rotation bands; load-bearing for the benchmark spectra in Tables 9 and 10.
WSGG coefficients for 4g-quadratic model [22] = Table 11
Coefficients fitted by Johansson et al. to SNBM training emissivities; used as a fixed input in this evaluation.
WSGG coefficients for 5g-quadratic model [22] = Table 12
Coefficients fitted by Johansson et al. to SNBM training emissivities; used as a fixed input in this evaluation.
WSGG coefficients for 5g-quadratic continuous model [24] = Table 13
Coefficients expressed as functions of H2O/CO2 molar ratio; applied here via piecewise-linear interpolation, as recommended in ref [18].
WSGG coefficients for 4g-linear model [25] = Table 14
Coefficients from Krishnamoorthy et al., fitted to an empirical correlation; used as a fixed input.
WSGG coefficients for 5g-cubic model [27] = Table 15
Coefficients fitted by Yin et al. to EWB training emissivities; used as a fixed input.
WSGG coefficients for 4g-cubic air-fuel model [28] = Table 16
Smith et al. coefficients for air-fuel conditions; included to estimate error when used in oxy-fuel environments.
ALBDF analytical fits for SLW = Analytic fits from refs [32] and [33]
Used to compute blackbody weights for the published SLW comparison; based on HITRAN 1991/1992 and noted to underpredict hot lines.

assumptions (6)

standard math Spectral radiative transfer equation and Planck function form
Equations (1) and (2) in Section 2 are treated as unproved background physics.
domain assumption Box/EWB block approximation accurately idealizes H2O and CO2 band structure
Section 2.1 assumes the Edwards-Menard and Felske-Tien correlations give reliable band equivalent widths at 1500 K for the two mixtures.
domain assumption WSGG representation with temperature-polynomial weights is adequate
Equation (11) in Section 2.2 assumes total emissivity can be represented as a weighted sum of gray gases; all six models inherit this form.
domain assumption SLW multiplication method assumes statistical independence of H2O and CO2 absorption cross-sections
Section 4.2 cites the multiplication method [34], which implies the cross-sections are statistically independent.
domain assumption HITRAN 1991/1992-based ALBDF fits are adequate at 1500 K
Section 4.2 acknowledges the database is low-temperature and may underpredict hot lines, yet the SLW comparison relies on these fits.
domain assumption Isothermal, homogeneous, non-scattering medium with constant wall temperature and emissivity
Section 3 defines the test problems as stagnant uniform gas at 1500 K with walls at 750 K and emissivity 0.725; this simplifies the radiation benchmark.

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Cite this review

Pith. "Pith review of Nongray EWB and WSGG Radiation Modeling in Oxy-Fuel Environments." pith.science (2026). https://pith.science/paper/AQHTJIAP

@misc{pith2026241116753,
  author       = {Pith},
  title        = {Pith review of: Nongray EWB and WSGG Radiation Modeling in Oxy-Fuel Environments},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/AQHTJIAP}},
  note         = {Machine review of arXiv:2411.16753}
}

abstract

According to a recent U.S. Greenhouse Gas Emissions Inventory (1), about 42% of 2008 CO$_2$ (a greenhouse gas) emissions in the US were from burning fossil fuels (especially coal) to generate electricity. The 2010 U.S. International Energy Outlook (2) predicts that the world energy generation using coal and natural gas will continue to increase steadily in the future. This results in increased concentrations of atmospheric CO$_2$, and calls for serious efforts to control its emissions from power plants through carbon capture technologies. Oxy-fuel combustion is a carbon capture technology in which the fossil fuel is burned in an atmosphere free from nitrogen, thereby significantly reducing the relative amount of N$_2$ in the flue-gas and increasing the mole fractions of H$_2$O and CO$_2$. This low concentration of N$_2$ facilitates the capture of CO$_2$. The dramatic change in the flue composition results in changes in its thermal, chemical, and radiative properties. From the modeling point of view, existing transport, combustion, and radiation models that have parameters tuned for air-fuel combustion (where N$_2$ is the dominant gaseous species in the flue) may need revision to improve the predictions of numerical simulations of oxy-fuel combustion. In this chapter, we consider recent efforts done to revise radiation modeling for oxy-fuel combustion, where five new radiative-property models were proposed to be used in oxy-fuel environments. All these models use the weighted-sum-of-gray-gases model (WSGGM). We apply and compare their performance in two oxy-fuel environments. Both environments consist of only H$_2$O and CO$_2$ as mixture species, and thus there is no N$_2$ dilution, but the environments vary in the mole fractions of these two species.

Discussion (0). Continue with ORCID to comment.

Reference graph

Works this paper leans on

14 extracted references · 14 canonical work pages

[1]

Greenhouse Gas Emissions Inventory (1), about 42% of 2008 CO, (a greenhouse gas) emissions in the U.S were from burning fossil fuels (especially coal) to generate electricity

Introduction According to a recent U.S. Greenhouse Gas Emissions Inventory (1), about 42% of 2008 CO, (a greenhouse gas) emissions in the U.S were from burning fossil fuels (especially coal) to generate electricity. The 2010 U.S. International Energy Outlook (2) predicts that the world energy generation using coal and natural gas will continue to increase...

work page 1982
[2]

From a molecular view, when k, is uniform along a path, 1/k, is the mean free path traveled by a photon until it is absorbed by an electron (3; 4)

Mathematical description The spectral radiative transfer equation (RTE) along a path s (with a unit vector $) in an emitting /absorbing medium is (3; 4) dIy(s,4y) TD = $0 Vly = ky(5s11) (Ing(517) ~ ys.) (a) where 77 is the wavenumber (its SI unit is 1/m), I, is the spectral radiative intensity (its SI unit W/m? m Steradian absorption coefficient (its SI u...

work page
[3]

It is advantageous to isolate the radiation modeling when examining different solution approaches, which is what we have followed here

Test cases In coupled combustion simulations, different sub-models interact and thus it becomes difficult to examine the independent response of a particular sub-model. It is advantageous to isolate the radiation modeling when examining different solution approaches, which is what we have followed here. The two test problems to be presented in this sectio...

work page
[4]

Results 4.1 Numerical settings The box/EWB model and each of the 6 WSGG models are applied to each of the 2 oxy-fuel environments. As mentioned in subsections 2.1 and 2.2, there are 22 RTEs per direction to resolve the spectrum for the box/EWB approach, and either 4 or 5 RTEs per direction to resolve the spectrum for the WSGG approach. We use the finite-v...

work page 1991
[5]

Conclusions We performed nongray radiation calculations of two radiation problems in homogeneous isothermal media. The first medium is typical of wet-recycle oxy-fuel combustion environment, with a molar composition of 65% COyz and 35% HO; whereas the second approximates a dry-recycle environment, with a molar composition of 90% CO» and 10% H20. The domai...

work page
[6]

Acknowledgments This technical effort was performed in support of the National Energy Technology Laboratory’s ongoing research in CO? Capture in the Existing Plants Emissions and Capture (EPEC) Technology Program. Dr. Marzouk activities were funded under the RES contract DE-FE0004000. The authors appreciate the help of Dr. Chungen Yin (Aalborg University,...

work page
[7]

Appendix A. ldealized spectra for the box/EWB approach This appendix presents numerically the idealized spectra of the linear absorption coefficients k; and the corresponding blackbody weights a; that were computed from the EWB approach for each of the two oxy-fuel environments. The values are used when solving the RTEs given in Equation (9). B. WSGG line...

work page
[8]

Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990 -U 2008,

References [1] [2] [3] [4] [5] [6] 7] [8] [9] [10] [11] [12] [13] [14] [15] [16] “Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990 -U 2008,” The United States Environmental Protection Agency (EPA), Washington, DC, 2010. “International Energy Outlook 2010,” The United States Energy Information Administration (EIA), Office of Integrated Analysis a...

work page 1990

Show all 14 references

[12]

The parameters for the vibration-rotation bands are those in (14) and for the pure-rotation bands are those in (15)

for the vibration-rotation bands, and using the Fleske-Tien theoretical expression (13; 15) for the pure-rotation band. The parameters for the vibration-rotation bands are those in (14) and for the pure-rotation bands are those in (15). Relating this approach to Equation (9), ...
[25]

35 40 0 20

30. 35 40 0 20. 25. 30.35 ~~40 Fig. 5. Centerline radiative source for 2 oxy-fuel environments Nongray EWB and WSGG Radiation Modeling in Oxy-Fuel Environments 505 4.5 Radiative-flux profiles The profiles of the radiative flux along the symmetry line of the 12x40 top wall for ...

1951
[34]

SLW Modeling of Radiative Transfer in Multicomponent Gas Mixtures,

V. P. Solovjov, B. W. Webb, “SLW Modeling of Radiative Transfer in Multicomponent Gas Mixtures,” Journal of Quantitative Spectroscopy & Radiative Transfer, vol. 65, pp. 655-672, 2000

2000
[35]

The TN Quadrature Set for the Discrete Ordinates Method,

C. P. Thurgood, A. Pollard, A. B. Becker, “The TN Quadrature Set for the Discrete Ordinates Method,” Journal of Heat Transfer, vol. 117, pp. 1068-1070, 1995

1995
[36]

The HITRAN Molecular Database: Editions of 1991 and 1992,

L. S. Rothman, R. R. Gamache, R. H. Tipping, C. P. Rinsland, M. A. H. Smith, D. C. Benner, V. M. Devi, J. M. Flaud, C. Camy-Peyret, A. Perrin, A. Goldman, S. T. Massie, L. R. Brown, “The HITRAN Molecular Database: Editions of 1991 and 1992,” Journal of Quantitative Spectroscop...

1991
[37]

Line-by-line and Narrow-band Statistical Model Calculations for HzO,

J. M. Hartmann, R. Levi Di Leon, J. Taine, “Line-by-line and Narrow-band Statistical Model Calculations for HzO,” Journal of Quantitative Spectroscopy & Radiative Transfer, vol. 32, pp. 119-127, 1984

1984

Pith tools

Reviewed August 12, 2026 · model on record in the stance chip above.

[1] [1]

Greenhouse Gas Emissions Inventory (1), about 42% of 2008 CO, (a greenhouse gas) emissions in the U.S were from burning fossil fuels (especially coal) to generate electricity

Introduction According to a recent U.S. Greenhouse Gas Emissions Inventory (1), about 42% of 2008 CO, (a greenhouse gas) emissions in the U.S were from burning fossil fuels (especially coal) to generate electricity. The 2010 U.S. International Energy Outlook (2) predicts that the world energy generation using coal and natural gas will continue to increase...

work page 1982

[2] [2]

From a molecular view, when k, is uniform along a path, 1/k, is the mean free path traveled by a photon until it is absorbed by an electron (3; 4)

Mathematical description The spectral radiative transfer equation (RTE) along a path s (with a unit vector $) in an emitting /absorbing medium is (3; 4) dIy(s,4y) TD = $0 Vly = ky(5s11) (Ing(517) ~ ys.) (a) where 77 is the wavenumber (its SI unit is 1/m), I, is the spectral radiative intensity (its SI unit W/m? m Steradian absorption coefficient (its SI u...

work page

[3] [3]

It is advantageous to isolate the radiation modeling when examining different solution approaches, which is what we have followed here

Test cases In coupled combustion simulations, different sub-models interact and thus it becomes difficult to examine the independent response of a particular sub-model. It is advantageous to isolate the radiation modeling when examining different solution approaches, which is what we have followed here. The two test problems to be presented in this sectio...

work page

[4] [4]

Results 4.1 Numerical settings The box/EWB model and each of the 6 WSGG models are applied to each of the 2 oxy-fuel environments. As mentioned in subsections 2.1 and 2.2, there are 22 RTEs per direction to resolve the spectrum for the box/EWB approach, and either 4 or 5 RTEs per direction to resolve the spectrum for the WSGG approach. We use the finite-v...

work page 1991

[5] [5]

Conclusions We performed nongray radiation calculations of two radiation problems in homogeneous isothermal media. The first medium is typical of wet-recycle oxy-fuel combustion environment, with a molar composition of 65% COyz and 35% HO; whereas the second approximates a dry-recycle environment, with a molar composition of 90% CO» and 10% H20. The domai...

work page

[6] [6]

Acknowledgments This technical effort was performed in support of the National Energy Technology Laboratory’s ongoing research in CO? Capture in the Existing Plants Emissions and Capture (EPEC) Technology Program. Dr. Marzouk activities were funded under the RES contract DE-FE0004000. The authors appreciate the help of Dr. Chungen Yin (Aalborg University,...

work page

[7] [7]

Appendix A. ldealized spectra for the box/EWB approach This appendix presents numerically the idealized spectra of the linear absorption coefficients k; and the corresponding blackbody weights a; that were computed from the EWB approach for each of the two oxy-fuel environments. The values are used when solving the RTEs given in Equation (9). B. WSGG line...

work page

[8] [8]

Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990 -U 2008,

References [1] [2] [3] [4] [5] [6] 7] [8] [9] [10] [11] [12] [13] [14] [15] [16] “Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990 -U 2008,” The United States Environmental Protection Agency (EPA), Washington, DC, 2010. “International Energy Outlook 2010,” The United States Energy Information Administration (EIA), Office of Integrated Analysis a...

work page 1990