manu prabha anand
Subscriber

 

LIBRARY:
  CEL:
    EXPRESSIONS:
      #####################################################################################################
      # Boundary Conditions
      #####################################################################################################
      BC Inlet Temperature     = 30 [C]
      BC Inlet Rel Humidity    = 0.40
      #####################################################################################################

      #####################################################################################################
      # Derived Boundary Condition Data BC
      #####################################################################################################
      # First determine the water vapour content in the gas phase based on the relative humidity and temperature
      BC Inlet Psat                     = 1[bar]*10^(H2O A – H2O B/(BC Inlet Temperature + H2O C-273.15[K]))
      BC Inlet Gas Phase H2O Mol Frac   = BC Inlet Rel Humidity*BC Inlet Psat/pabs
      BC Inlet Gas Phase Air Mol Frac   = 1 – BC Inlet Gas Phase H2O Mol Frac
      # Determine molar mass of the mixture
      BC Inlet Gas Phase Mix Molar Mass = Molar Mass Water*BC Inlet Gas Phase H2O Mol Frac +  Molar Mass Air*BC Inlet Gas Phase Air Mol Frac
      # Convert molar fraction into mass fraction for the gas phase
      BC Inlet Gas Phase H2O Mass Frac =  (BC Inlet Gas Phase H2O Mol Frac*Molar Mass Water)/BC Inlet Gas Phase Mix Molar Mass
      BC Inlet Gas Phase Air Mass Frac = 1-BC Inlet Gas Phase H2O Mass Frac
  END
  END
END

LIBRARY:
  CEL:
    EXPRESSIONS:

      #####################################################################################################
      # Material Properties
      #####################################################################################################
      # Molar Mass
      Molar Mass Water = 18.02 [kg kmol^-1]
      Molar Mass Air   = 28.96 [kg kmol^-1]

      # Antoine Constants for Water (Poling et al.)
      H2O A = 5.11564
      H2O B = 1687.537 [K]
      H2O C = 230.17 [K]

      # Kinematic Diffusivity Vapor (Sutherland)
      My Mix Kinematic Diffusivity = (0.292[cm^2 s^-1 bar]/(pabs) ) *(T/313.0[K])^(3/2)
      #####################################################################################################

    END
  END
END

I have used the above sample code provided by ansys.I am having a doubt. how is pabs calculated. what is pabs, why is it kept as a variable? 
 
I want to calculate some other parameter called Heat capacity ratio of mixture, but i am not getting “BC Inlet Gas Phase Air Mol Frac and BC Inlet Gas Phase H2O Mol Frac” it is not giving output, it is shown as variable, how to calculate these values after simualtion?