#*-------------------------------------------------------------------
* 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 (Revised Gerson B. Bicca)
* $Id: compressor.mso 608 2008-08-25 05:11:12Z bicca $
*--------------------------------------------------------------------*#

using "streams";

Model centrifugal_compressor
	
ATTRIBUTES
	Pallete 	= true;
	Icon 		= "icon/CentrifugalCompressor"; 
	Brief 		= "Model of a centrifugal compressor.";
	Info 		=
"To be documented";
	
PARAMETERS

outer PP   					as Plugin	 		(Brief = "External Physical Properties", Type="PP");
outer NComp   			as Integer			(Brief = "Number of chemical components", Lower = 1);
	Rgas						as positive 		(Brief = "Constant of Gases", Unit= 'kJ/kmol/K', Default = 8.31451,Hidden=true);
	Mw(NComp) 			as molweight 	(Brief = "Molar Weight");
	CompressorType 	as Switcher		(Brief = "Compressor Model Type",Valid=["Polytropic Operation","Isentropic Operation"], Default="Isentropic Operation");

VARIABLES

	Pratio	 	as positive		(Brief = "Pressure Ratio", Symbol ="P_{ratio}");	
	Pdrop		as press_delta	(Brief = "Pressure Drop", DisplayUnit = 'kPa', Symbol ="\Delta P");
	Pincrease	as press_delta	(Brief = "Pressure Increase", DisplayUnit = 'kPa', Symbol ="P_{incr}");

	Head 			as energy_mass	(Brief = "Actual Head",Hidden=true);
	HeadIsentropic 	as energy_mass	(Brief = "Isentropic Head");
	HeadPolytropic 	as energy_mass	(Brief = "Polytropic Head");
	
	EfficiencyOperation 	as positive 	(Brief = "Compressor efficiency - Polytropic or Isentropic (See Compressor Type)",Lower=1E-3,Upper=1);
	MechanicalEff 			as positive 	(Brief = "Mechanical efficiency",Lower=1E-3,Upper=1);
	
	FluidPower	as power	(Brief = "Fluid Power");
	BrakePower	as power	(Brief = "Brake Power");
	PowerLoss	as power	(Brief = "Power Losses");
	
	PolyCoeff			as positive		(Brief = "Polytropic Coefficient", Lower=0.2,Protected=true);
	IseCoeff 			as positive 	(Brief = "Isentropic Coefficient", Lower=0.2,Protected=true); 
	PolytropicEff  		as positive 	(Brief = "Polytropic efficiency",Lower=1E-3,Upper=1,Protected=true);
	IsentropicEff 		as positive 	(Brief = "Isentropic efficiency",Lower=1E-3,Upper=1,Protected=true);

	Tisentropic	as temperature  	(Brief = "Isentropic Temperature",Protected=true); 
	Mwm			as molweight    	(Brief = "Mixture Molar Weight",Protected=true);
	rho			as dens_mass    	(Brief = "Mass Density",Protected=true);
	Zfac_in		as fraction    		(Brief = "Compressibility factor at inlet",Protected=true);
	Zfac_out 	as fraction    		(Brief = "Compressibility factor at outlet",Protected=true);

in	Inlet 	as stream	(Brief = "Inlet stream", PosX=0.437, PosY=1, Symbol="_{in}");
out	Outlet 	as streamPH	(Brief = "Outlet stream", PosX=0.953, PosY=0.0, Symbol="_{out}");

in 	WorkIn	as power	(Brief = "Work Inlet", PosX=0, PosY=0.45);

SET

	Mw = PP.MolecularWeight();

	Rgas	= 8.31451*'kJ/kmol/K';

EQUATIONS

"Overall Molar Balance"
	Outlet.F = Inlet.F;

"Component Molar Balance"
	Outlet.z = Inlet.z;

"Average Molecular Weight"
	Mwm = sum(Mw*Inlet.z);

"Pressure Ratio"
	Outlet.P = Inlet.P * Pratio;

"Pressure Drop"
	Outlet.P  = Inlet.P - Pdrop;

"Pressure Increase"
	Outlet.P  = Inlet.P + Pincrease;

"Mass Density"
	rho = PP.VapourDensity(Inlet.T, Inlet.P, Inlet.z);

"Compressibility factor at Inlet Conditions"
	Zfac_in = PP.VapourCompressibilityFactor(Inlet.T,Inlet.P,Inlet.z);

"Compressibility factor at Outlet Conditions"
	Zfac_out = PP.VapourCompressibilityFactor(Outlet.T,Outlet.P,Outlet.z);

"Isentropic Head"
	HeadIsentropic*Mwm = (PP.VapourEnthalpy(Tisentropic,Outlet.P,Outlet.z)-Inlet.h);

"Actual Head"
	Head*Mwm = (Outlet.h-Inlet.h);

"Isentropic Outlet Temperature"
	PP.VapourEntropy(Tisentropic, Outlet.P, Outlet.z) = PP.VapourEntropy(Inlet.T, Inlet.P, Inlet.z);

"Brake Power"
	BrakePower = -WorkIn;

"Brake Power"
	BrakePower*MechanicalEff = FluidPower;

"Power Loss"
	PowerLoss = BrakePower - FluidPower;

"Isentropic Efficiency"
	IsentropicEff*(PP.VapourEnthalpy(Outlet.T,Outlet.P,Outlet.z)-Inlet.h) = (PP.VapourEnthalpy(Tisentropic,Outlet.P,Outlet.z)-Inlet.h);

"Polytropic-Isentropic Relation"
	PolytropicEff*HeadIsentropic = HeadPolytropic*IsentropicEff;

"Polytropic Efficiency"
	PolytropicEff*IseCoeff*(PolyCoeff-1) = PolyCoeff*(IseCoeff-1);

"Isentropic Coefficient"
	HeadIsentropic = (0.5*Zfac_in+0.5*Zfac_out)*(1/Mwm)*(IseCoeff/(IseCoeff-1.001))*Rgas*Inlet.T*((Outlet.P/Inlet.P)^((IseCoeff-1.001)/IseCoeff) - 1);

"Polytropic Coefficient"
	HeadPolytropic = (0.5*Zfac_in+0.5*Zfac_out)*(1/Mwm)*(PolyCoeff/(PolyCoeff-1.001))*Rgas*Inlet.T*((Outlet.P/Inlet.P)^((PolyCoeff-1.001)/PolyCoeff) - 1);

"Fluid Power"
	FluidPower = Head*sum(Mw*Inlet.z)*Inlet.F*EfficiencyOperation+PowerLoss;

switch CompressorType

	case "Isentropic Operation":

"Efficiency"
	EfficiencyOperation = IsentropicEff;
	
	case "Polytropic Operation":

"Efficiency"
	EfficiencyOperation = PolytropicEff;

end


end