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##### CFX / Re: Combustor efficiency

« Last post by**william**on

*November 12, 2016, 06:20:29 PM*»

The ccl below uses the CEL expression CombEff to adjust the heating values:

LIBRARY:

MATERIAL: Methane Air WD1

Option = Variable Composition Mixture

Reactions List = Methane Air WD1

END # MATERIAL Methane Air WD1

MATERIAL : CH4 # Methane

Option = Pure Substance

PROPERTIES :

Option = Ideal Gas

Molar Mass = 16.04 [kg kmol^-1]

Dynamic Viscosity = 11.1E-06 [kg m^-1 s^-1]

Thermal Conductivity = 343E-04 [W m^-1 K^-1]

Thermal Expansivity = 3.35E-03 [K^-1]

Refractive Index = 1.

Reference Pressure = 1. [atm]

Reference Temperature = 25 [C]

Reference Specific Enthalpy = -74.87310 [kJ mol^-1] / 16.04 [kg kmol^-1]

Reference Specific Entropy = 186.2 [J mol^-1 K^-1] / 16.04 [kg kmol^-1]

SPECIFIC HEAT CAPACITY:

Option = NASA Format

Temperature Limit List = 300 [K], 5000 [K], 1000 [K]

NASA Coefficient List =

NASACoeff21, NASACoeff22, NASACoeff23,

NASACoeff24, NASACoeff25, NASACoeff26,

NASACoeff27,

NASACoeff11, NASACoeff12, NASACoeff13,

NASACoeff14, NASACoeff15, NASACoeff16,

NASACoeff17

END #SPECIFIC HEAT CAPACITY

#

# Boiling point (1 atm) = 111.66 [K]

# Critical Temperature = 190.58 [K]

# Critical Pressure = 4.604E+06 [Pa]

#

END #PROPERTIES

END #MATERIAL

CEL:

EXPRESSIONS:

#

# Combustion of methane: CH4 + 2O2 -> CO2 + 2H2O

#

Rgas = 8314.41 [J kmol^-1]

CombEff = 0.95

HoFCO2 = -393.5224 [kJ mol^-1]

HoFH2O = -241.8264 [kJ mol^-1]

HoFCH4 = -74.8731 [kJ mol^-1]

HeatofProducts = HoFCO2+2*HoFH2O

HeatofReaction = HeatofProducts-HoFCH4

#

# Modify heat of formation ofmethane to account for a

# combustion efficiency of less than 100% using Gordon

# & McBride (NASA) format for enthalpy polynomial

#

HoFCH4Mod = HeatofProducts-CombEff*HeatofReaction

#

NASACoeff11 = 0.07787415E+01

NASACoeff12 = 0.01747668E+00

NASACoeff13 = -0.02783409E-03

NASACoeff14 = 0.03049708E-06

NASACoeff15 = -0.01223931E-09

NASACoeff17 = 0.01372219E+03

Tref1 = 298.15

DHTref11 = NASACoeff11*Tref1 + NASACoeff12*Tref1^2/2 +

NASACoeff13*Tref1^3/3 + NASACoeff14*Tref1^4/4 + NASACoeff15*Tref1^5/5

Tref2 = 1000.0

DHTref12 = NASACoeff11*Tref2 + NASACoeff12*Tref2^2/2 +

NASACoeff13*Tref2^3/3 + NASACoeff14*Tref2^4/4 +

NASACoeff15*Tref2^5/5

NASACoeff16 = HoFCH4Mod/Rgas-DHTref11

# NASACoeff16 = -0.09825229E+05

#

# High temperature polynomial

#

NASACoeff21 = 0.01683479E+02

NASACoeff22 = 0.01023724E+00

NASACoeff23 = -0.03875129E-04

NASACoeff24 = 0.06785585E-08

NASACoeff25 = -0.04503423E-12

NASACoeff27 = 0.09623395E+02

DHTref22 = NASACoeff21*Tref2 + NASACoeff22*Tref2^2/2 +

NASACoeff23*Tref2^3/3 + NASACoeff24*Tref2^4/4 +

NASACoeff25*Tref2^5/5

# Ensure high T and low T polynomials match at Tref2

NASACoeff26 = DHTref12 + NASACoeff16 - DHTref22

# NASACoeff26 = -0.01008079E+06

#

END # EXPRESSIONS

END # CEL

END # LIBRARY

FLOW:

DOMAIN: Combustor

Location = Combustor

Coord Frame = Coord 0

Fluids List = Methane Air WD1

DOMAIN MODELS:

DOMAIN MOTION:

Option = Stationary

END # DOMAIN MOTION

BUOYANCY MODEL:

Option = Non Buoyant

END # BUOYANCY MODEL

REFERENCE PRESSURE:

Reference Pressure = 1.0133E5 [Pa]

END # REFERENCE PRESSURE

END # DOMAIN MODELS

FLUID MODELS:

TURBULENCE MODEL:

Option = k epsilon

END # TURBULENCE MODEL

TURBULENT WALL FUNCTIONS:

Option = Scalable

END # TURBULENT WALL FUNCTIONS

HEAT TRANSFER MODEL:

Option = Thermal Energy

END # HEAT TRANSFER MODEL

COMBUSTION MODEL:

Option = Eddy Dissipation

END # COMBUSTION MODEL

COMPONENT: CH4

Option = Transport Equation

END # COMPONENT CH4

COMPONENT: O2

Option = Transport EquationEND # COMPONENT O2

COMPONENT: CO2

Option = Transport Equation

END # COMPONENT CO2

COMPONENT: H2O

Option = Transport Equation

END # COMPONENT H2O

COMPONENT: N2

Option = Constraint

END # COMPONENT N2

THERMAL RADIATION MODEL:

Option = None

END # THERMAL RADIATION MODEL

END # FLUID MODELS

END # DOMAIN Combustor

END #FLOW

LIBRARY:

MATERIAL: Methane Air WD1

Option = Variable Composition Mixture

Reactions List = Methane Air WD1

END # MATERIAL Methane Air WD1

MATERIAL : CH4 # Methane

Option = Pure Substance

PROPERTIES :

Option = Ideal Gas

Molar Mass = 16.04 [kg kmol^-1]

Dynamic Viscosity = 11.1E-06 [kg m^-1 s^-1]

Thermal Conductivity = 343E-04 [W m^-1 K^-1]

Thermal Expansivity = 3.35E-03 [K^-1]

Refractive Index = 1.

Reference Pressure = 1. [atm]

Reference Temperature = 25 [C]

Reference Specific Enthalpy = -74.87310 [kJ mol^-1] / 16.04 [kg kmol^-1]

Reference Specific Entropy = 186.2 [J mol^-1 K^-1] / 16.04 [kg kmol^-1]

SPECIFIC HEAT CAPACITY:

Option = NASA Format

Temperature Limit List = 300 [K], 5000 [K], 1000 [K]

NASA Coefficient List =

NASACoeff21, NASACoeff22, NASACoeff23,

NASACoeff24, NASACoeff25, NASACoeff26,

NASACoeff27,

NASACoeff11, NASACoeff12, NASACoeff13,

NASACoeff14, NASACoeff15, NASACoeff16,

NASACoeff17

END #SPECIFIC HEAT CAPACITY

#

# Boiling point (1 atm) = 111.66 [K]

# Critical Temperature = 190.58 [K]

# Critical Pressure = 4.604E+06 [Pa]

#

END #PROPERTIES

END #MATERIAL

CEL:

EXPRESSIONS:

#

# Combustion of methane: CH4 + 2O2 -> CO2 + 2H2O

#

Rgas = 8314.41 [J kmol^-1]

CombEff = 0.95

HoFCO2 = -393.5224 [kJ mol^-1]

HoFH2O = -241.8264 [kJ mol^-1]

HoFCH4 = -74.8731 [kJ mol^-1]

HeatofProducts = HoFCO2+2*HoFH2O

HeatofReaction = HeatofProducts-HoFCH4

#

# Modify heat of formation ofmethane to account for a

# combustion efficiency of less than 100% using Gordon

# & McBride (NASA) format for enthalpy polynomial

#

HoFCH4Mod = HeatofProducts-CombEff*HeatofReaction

#

NASACoeff11 = 0.07787415E+01

NASACoeff12 = 0.01747668E+00

NASACoeff13 = -0.02783409E-03

NASACoeff14 = 0.03049708E-06

NASACoeff15 = -0.01223931E-09

NASACoeff17 = 0.01372219E+03

Tref1 = 298.15

DHTref11 = NASACoeff11*Tref1 + NASACoeff12*Tref1^2/2 +

NASACoeff13*Tref1^3/3 + NASACoeff14*Tref1^4/4 + NASACoeff15*Tref1^5/5

Tref2 = 1000.0

DHTref12 = NASACoeff11*Tref2 + NASACoeff12*Tref2^2/2 +

NASACoeff13*Tref2^3/3 + NASACoeff14*Tref2^4/4 +

NASACoeff15*Tref2^5/5

NASACoeff16 = HoFCH4Mod/Rgas-DHTref11

# NASACoeff16 = -0.09825229E+05

#

# High temperature polynomial

#

NASACoeff21 = 0.01683479E+02

NASACoeff22 = 0.01023724E+00

NASACoeff23 = -0.03875129E-04

NASACoeff24 = 0.06785585E-08

NASACoeff25 = -0.04503423E-12

NASACoeff27 = 0.09623395E+02

DHTref22 = NASACoeff21*Tref2 + NASACoeff22*Tref2^2/2 +

NASACoeff23*Tref2^3/3 + NASACoeff24*Tref2^4/4 +

NASACoeff25*Tref2^5/5

# Ensure high T and low T polynomials match at Tref2

NASACoeff26 = DHTref12 + NASACoeff16 - DHTref22

# NASACoeff26 = -0.01008079E+06

#

END # EXPRESSIONS

END # CEL

END # LIBRARY

FLOW:

DOMAIN: Combustor

Location = Combustor

Coord Frame = Coord 0

Fluids List = Methane Air WD1

DOMAIN MODELS:

DOMAIN MOTION:

Option = Stationary

END # DOMAIN MOTION

BUOYANCY MODEL:

Option = Non Buoyant

END # BUOYANCY MODEL

REFERENCE PRESSURE:

Reference Pressure = 1.0133E5 [Pa]

END # REFERENCE PRESSURE

END # DOMAIN MODELS

FLUID MODELS:

TURBULENCE MODEL:

Option = k epsilon

END # TURBULENCE MODEL

TURBULENT WALL FUNCTIONS:

Option = Scalable

END # TURBULENT WALL FUNCTIONS

HEAT TRANSFER MODEL:

Option = Thermal Energy

END # HEAT TRANSFER MODEL

COMBUSTION MODEL:

Option = Eddy Dissipation

END # COMBUSTION MODEL

COMPONENT: CH4

Option = Transport Equation

END # COMPONENT CH4

COMPONENT: O2

Option = Transport EquationEND # COMPONENT O2

COMPONENT: CO2

Option = Transport Equation

END # COMPONENT CO2

COMPONENT: H2O

Option = Transport Equation

END # COMPONENT H2O

COMPONENT: N2

Option = Constraint

END # COMPONENT N2

THERMAL RADIATION MODEL:

Option = None

END # THERMAL RADIATION MODEL

END # FLUID MODELS

END # DOMAIN Combustor

END #FLOW