Isenthalpic Pressure Drop (Basic)

This is very simple pressure drop model.
Outlet temperature is calculated in condition of isenthalpic pressure drop.
Outlet molar volume is also calculated, since the downstream requires the information.
This model can be exported as an installer (MSI file).
If you install, you can leverage this model in Aspen Plus.

Download ACM file (V8.8)

Download MSI file (V8.8)

Download Aspen Plus file (V8.8)

Model IsenthalpicPressureDrop

  // Variables
  F                As flow_mol     (Description:"Molar flow rate");
  z(ComponentList) As molefraction (Description:"Mixture mole fraction",
                                    1/Size(ComponentList));
  y(ComponentList) As molefraction (Description:"Outlet vapor mole fraction",
                                    1/Size(ComponentList));
  x(ComponentList) As molefraction (Description:"Outlet liquid mole fraction",
                                    1/Size(ComponentList));
  vf               As vapfraction  (Description:"Outlet vapor molar fraction");
  T                As temperature  (Description:"Outlet temperature");
  Pin              As pressure     (Description:"Inlet pressure");
  P                As pressure     (Description:"Outlet pressure");
  dP               As press_diff   (Description:"Pressure drop", Fixed, 0.1);
  h                As enth_mol     (Description:"Outlet mixture molar enthalpy");
  hv               As enth_mol_vap (Description:"Outlet vapor molar enthalpy");
  hl               As enth_mol_liq (Description:"Outlet liquid molar enthalpy");
  rho              As dens_mol     (Description:"Outlet mixture molar density");
  rhov             As dens_mol     (Description:"outlet vapor molar density");
  rhol             As dens_mol     (Description:"Outlet liquid molar density");
  V                As vol_mol      (Description:"Outlet mixture molar volume");
  Vv               As vol_mol      (Description:"Outlet vapor molar volume");
  Vl               As vol_mol      (Description:"Outlet liquid molar volume");
  
  // Ports
  In_F  As Input  MoleFractionPort(Description:"Feed");
  Out_P As Output MoleFractionPort(Description:"Product");

  // Inlet variables
  F   = In_F.F;
  z   = In_F.z;
  Pin = In_F.P;
  h   = In_F.h;

  // Pressure drop calculation
  P = Pin - dP;

  // Two phase flash at given pressure and molar enthalpy
  Call (T, vf, y, x, hv, hl) = pFlashPH(P, h, z);

  // Outlet molar volume
  Call (rhov) = pDens_Mol_Vap(T, P, y);
  Call (rhol) = pDens_Mol_Liq(T, P, x);
  V = vf / rhov + (1 - vf) / rhol;  
  
  // Outlet variables
  Out_P.F = F;
  Out_P.z = z;
  Out_P.T = T;
  Out_P.P = P;
  Out_P.h = h;
  Out_P.V = V;

End

The results were compared with the valve model of Aspen Plus Dynamics.

The model can be utilized in Aspen Plus.