**7. Appendix**

14 Numerical Simulations / Book 1

**|q R | [kW/m2** 

transfer for both environments. Although the relative error with respect to the box/EWB is smaller than the error recorded for the 1D flux profile, the relative error for the dry-recycle environment is larger than the relative error for the wet-recycle environment. All the oxy-fuel

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Average wall radiative flux

(kW/m2)

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% CO2 and 35% H2O; whereas the second approximates a dry-recycle environment, with a molar composition of 90% CO2 and 10% H2O. The domain was a 12×12×40 m rectangular enclosure at 1 500 K. For each environment, we generated reference solutions using the box model based on the exponential wide band approach. We also calculated solutions using five (recent) oxy-fuel and one (older) air-fuel weighted-sum-of-gray-gases models that were proposed in the literature. Comparing

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**10% H 2O + 90% CO 2**

**]**

**Z [m]**

%Error

(relative to box/EWB)

**EWB 4g, quad 5g, quad 5g, quad, (cont) 4g, linear 5g, cubic 4g, cubic, (air)**

**<sup>0</sup> <sup>10</sup> <sup>20</sup> <sup>30</sup> <sup>40</sup> <sup>55</sup>**

**Z [m]**

Fig. 6. Radiative flux along the midline of the 12×40 top wall

transfer (MW)

WSGG models overpredict the heat transfer, but the error is within 10.4%.

box/EWB 224.74 101.78 0.00% 4g, quadratic 244.18 110.59 + 8.65% 5g, quadratic 246.48 111.63 + 9.67% 5g, quadratic, (cont) 233.99 105.97 + 4.12% 4g, linear 238.15 107.86 + 5.97% 5g, cubic 235.43 106.62 + 4.76% 4g, cubic, (air) 191.63 86.79 −14.73% Table 7. Wall radiative heat transfer for the oxy-fuel environment with 65%CO2

**EWB 4g, quad 5g, quad 5g, quad, (cont) 4g, linear 5g, cubic 4g, cubic, (air)**

**<sup>0</sup> <sup>10</sup> <sup>20</sup> <sup>30</sup> <sup>40</sup> <sup>55</sup>**

Solution method Wall radiative heat

**|q R | [kW/m2 ]**

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**5. Conclusions**

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