source: trunk/eml/pressure_changers/compressor.mso @ 286

#*-------------------------------------------------------------------
* EMSO Model Library (EML) Copyright (C) 2004 - 2007 ALSOC.
*
* This LIBRARY is free software; you can distribute it and/or modify
* it under the therms of the ALSOC FREE LICENSE as available at
* http://www.enq.ufrgs.br/alsoc.
*
* EMSO Copyright (C) 2004 - 2007 ALSOC, original code
* from http://www.rps.eng.br Copyright (C) 2002-2004.
* All rights reserved.
*
* EMSO is distributed under the therms of the ALSOC LICENSE as
* available at http://www.enq.ufrgs.br/alsoc.
*
*----------------------------------------------------------------------
* Author: Marcos L. Alencastro,  Estefane S. Horn
* $Id: compressor.mso 277 2007-06-16 20:17:45Z paula $
*--------------------------------------------------------------------*#

using "pressure_changers/flux_machine_basic";

Model centrifugal_compressor as flux_machine_basic_PH
        ATTRIBUTES
        Pallete         = true;
        Icon            = "CentrifugalCompressor"; 
        Brief           = "Model of a centrifugal compressor.";
        Info            =
        "Assumptions:
         * Steady State;
         * Only Vapor;
         * Adiabatic.
        
        Specify: 
         * the inlet stream;
         * the outlet pressure (Outlet.P);
         * the Isentropic efficiency (Effs).
        ";
        
        PARAMETERS
outer PP                as Plugin               (Brief = "External Physical Properties", Type="PP");
outer NComp     as Integer              (Brief = "Number of chemical components", Lower = 1);
        R                       as positive     (Default = 8.31451, Brief = "Constant of Gases", Unit= 'kJ/kmol/K');
        Mw(NComp)       as molweight    (Brief = "Molar Weight");

        VARIABLES
        n                       as positive             (Brief = "Politropic Coefficient", Lower=0);
        k                       as positive     (Brief = "Isentropic Coefficient", Lower=0); 
        Cp              as cp_mol               (Brief = "Heat Capacity");
        Cv                      as cv_mol               (Brief = "Heat Capacity");
        Pdiff           as press_delta  (Brief = "Pressure Increase", DisplayUnit='kPa');
        Pratio          as positive             (Brief = "Pressure Ratio");     
        Wp                      as energy_mol   (Brief = "Politropic Head");
        Ws                      as energy_mol   (Brief = "Isentropic Head");
        Tiso            as temperature  (Brief = "Isentropic Temperature"); 
        Effp            as efficiency   (Brief = "Politropic efficiency");
        Effs            as efficiency   (Brief = "Isentropic efficiency");
        FPower          as power                (Brief = "Fluid Power");
        Mwm                     as molweight    (Brief = "Mixture Molar Weight");

        SET
        Mw = PP.MolecularWeight();
        
        EQUATIONS
        
        "Calculate Mwm for Inlet Mixture"
        Mwm = sum(Mw*Inlet.z);

        "Calculate Outlet Stream Pressure"
        Outlet.P = Inlet.P + Pdiff;
        
        "Pratio Definition"
        Outlet.P = Inlet.P * Pratio;
        
        "Calculate Cp Using a External Physical Properties Routine"
        Cp = PP.VapourCp(Inlet.T,Inlet.P,Inlet.z);
        
        "Calculate Cv Using a External Physical Properties Routine"
        Cv = PP.VapourCv(Inlet.T,Inlet.P,Inlet.z);
        
        "Calculate Isentropic Coeficient"
        k * Cv = Cp;
        
        "Calculate Isentropic Head"
        Ws = (k/(k-1))*R*Inlet.T*((Outlet.P/Inlet.P)^((k-1)/k) - 1);
        
        "Calculate Isentropic Outlet Temperature"
        Tiso = Inlet.T * (Outlet.P/Inlet.P)^((k-1)/k);
        
        "Calculate Real Outlet Temperature"
        Effs * (Outlet.T- Inlet.T) = (Tiso - Inlet.T);
        
        "Calculate Politropic Coefficient"
        n*(ln(Outlet.T/Inlet.T)) = (n-1)*(ln(Outlet.P/Inlet.P));
        
        "Calculate Politropic Efficiency"
        Effp * (n-1) * k = n * (k-1);
        
        "Calculate Politropic Head"
        Ws*Effp = Wp*Effs;

        "Calculate Fluid Power"
        FPower*Effs = Inlet.F*Ws;
        
        "Molar Balance"
        Outlet.F = Inlet.F;
        
        Outlet.z = Inlet.z;
end