I would like to reduce the heating values of gases in a combustion simulation to represent a low combustion efficiency. How can I modify the NASA coefficients?

 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 WD1MATERIAL : 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**** Entered By: dsclarke @ 12/22/2005 08:46 AM ****

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