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32.3.9 Define/Models/Species/NOx...

The Define/Models/Species/NOx... menu item opens the NOx Model panel.



NOx Model Panel


The NOx Model panel allows you to set parameters related to the NOx postprocessor. See Section  20.1.10 for details about the items below.

figure

Controls

Formation   tab contains the parameters to define NOxmodel.
Pathways   contains toggle buttons for activating the NOx models to be used for the calculation of NO and HCN concentrations.
Thermal NO   enables calculation of thermal NOx.

Prompt NO   enables the calculation of prompt NOx.

Fuel NO   enables the calculation of fuel NOx.

N2O Intermediate   enables the formation of NOx through N2O Intermediate. This option will appear only if one of the NO model is active.

User-Defined Functions   contains controls for selecting a NOx Rate UDF. See the separate UDF Manual for details.

Replace with UDF Rate   replaces any or all of FLUENT's NOx rate calculations with your own user-defined NOx rate

Reduction   tab contains the reduction parameters.
Methods   contains list of reduction methods.

Reduction Method Parameters   (This item will not appear until one of the other Models is turned on.)
Reburn   enables the calculation of NO reburning effects.

SNCR   enables the calculation of NOxreduction by SNCR method.

Turbulence Interaction   contains parameters related to the effect of turbulent fluctuations on the NOx formation. See Section  20.1.9 for details.

PDF Mode   is a drop-down list containing options that take into account turbulent fluctuations when you compute the specified NO formation. See Section  20.1.10 for details.
temperature   includes fluctuations of temperature.

temperature/species   fluctuations of temperature and mass fraction of the species selected in the Species drop-down list (which appears when you select this option).

Mixure Fraction   includes fluctuation in the mixture fraction(s). This is available for non-premixed combustion calculations only.

Beta PDF Points   controls the number of points at which the beta function in Equation  20.1-104 or Equation  20.1-105 will be integrated. The default value of 10, which indicates that the beta function will be integrated at 10 points on a histogram basis, will yield an accurate solution with reasonable computation time. Increasing this value may improve accuracy, but will also increase the computation time. (This item will appear only if you have selected one of the four PDF modes for turbulence interaction.)

Formation Model Parameters   contains the parameters associated with the selected
NOxmodel.

Thermal   contains parameters for modeling thermal NO. (This section will appear only if Thermal NO is enabled under Models.)

[O] Model   is a drop-down list in which you can select the method to be used for calculation of thermal NOx. To choose the equilibrium method, select equilibrium. To choose the partial equilibrium method, select partial-equilibrium. To choose the predicted O concentration method, select instantaneous. See Section  20.1.3, 20.1.3, and 20.1.3 for details.

[OH] Model   is a drop-down list in which you can select the method to be used for calculation of thermal NOx. To exclude OH, select none. To choose the partial equilibrium method, select partial-equilibrium. To choose the predicted OH concentration method, select instantaneous. See Sections  20.1.3, 20.1.3, and 20.1.3 for details.

Replace with UDF Rate   replaces any or all of FLUENT's NOx rate calculations with your own user-defined NOx rate.

Prompt   contains parameters for modeling prompt NO. (This section will appear only if Prompt NO is enabled under Models.)

Fuel Species   is a list containing all of the defined species. You will select the species that is the fuel.

Fuel Carbon Number   specifies the number of carbon atoms per fuel molecule.

Equivalence Ratio   is the ratio of the actual fuel/air ratio to the stoichiometric fuel/air ratio.

Fuel   contains parameters for modeling fuel NO. (This section will appear only if Fuel NO is enabled under Models.)

Fuel Type   specifies the type of fuel NOx to be calculated.

Solid   enables the calculation of solid fuel NOx.

Liquid   enables the calculation of liquid fuel NOx.

Gas   enables the calculation of gas fuel NOx.

N Intermediate   allows you to specify any one of the HCN, NH3, or
HCN/NH3/NO as the intermediate species. See Section  20.1.5 for details.

Volatile N Mass Fraction   specifies the mass fraction of nitrogen in the volatiles. This parameter appears only for Solid fuel NOx calculations.

Conversion Fraction   specifies the overall fraction of fuel N (for gas and liquid) or volatile N (for solid), by mass, that will be converted to immediate species and/or product NO. This option will appear only if you have selected HCN/NH3/NO as the intermediate species.

Partition Fractions   specifies the fraction of the converted fuel N (for gas and liquid) or volatile N (for solid), by mass, that will become HCN and NH3. This option will appear only if you have selected HCN/NH3/NO as the intermediate species.

Char N Conversion   is a drop-down list in which you can select NO, HCN, or NH3 as the species to which the char N is converted (when you are calculating solid fuel NOx). This parameter appears only for Solid fuel NOx calculations. See Section  20.1.10 for details.

Char N Mass Fraction   specifies the mass fraction of nitrogen in the char. This parameter appears only for Solid fuel NOx calculations.

BET Surface Area   sets the BET internal pore surface area (see
Section  20.1.5 for details) of the particles. This parameter appears only for Solid fuel NOx calculations.

Fuel N Mass Fraction   specifies the mass fraction of nitrogen in the fuel (kg nitrogen per kg fuel). This parameter appears only for Gas or Liquid fuel NOx calculations.

N2O Path   contains the method to be used for formation of NO through an $N_2$O intermediate. (This section will appear only if N2O Intermediate is enabled under Models.)

N2O Model   contains the drop-down list of available N2O models.
quasi-steady   enables the quasi-steady-state method of calculation (The transport equation for the species $N_2$O will not be solved).

transported-simple   enables the transported simple method of calculation (The pollutant species $N_2$O is added in the species list and it's mass fraction will be calculated using the transport equations).

[ Reduction Method Parameters] contains the methods of reduction.

Reburn   tab activates the NOxreduction by reburn method.

Reburn Model   contains the drop-down list of reburn methods.
instantaneous[CH]   activates instantaneous method in the Reburn Model. When you choose this method a warning to include CH, $CH_2$, and $CH_3$ will be displayed.

partial-equilibrium   activates partial method in the Reburn Model.

Reburn Fuel Species   contains reburn fuel species drop-down list.

Equivalent Fuel Type   contains equivalent fuel type drop-down list.

SNCR   contains the drop-down list of SNCR methods
Injection Method   contains the parameters for NOxreduction by SNCR method.
Gaseous Injection   includes ammonia as a gas phase pollutant species from the injection locations.

Liquid Injection   includes liquid phase pollutant species from the injection locations.

Reagent Species   contains the list of the liquid phase pollutants available. This option is available only if the Liquid Injection is selected as Injection Method.


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