#*-------------------------------------------------------------------
* 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.
*
*----------------------------------------------------------------------
* Authors: Rafael de Pelegrini Soares
*          Andrey Copat, Estefane S. Horn, Marcos L. Alencastro
* $Id$
*--------------------------------------------------------------------*#

using "streams";

Model expander
	
ATTRIBUTES
	Pallete 	= true;
	Icon 		= "icon/expander"; 
	Brief 		= "Model of an expansor.";
	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");

VARIABLES

	IseCoeff 	as positive 	(Brief = "Isentropic Coefficient", Lower=0.2); 
	Pratio	 	as positive		(Brief = "Pressure Ratio", Symbol ="P_{ratio}");	
	Pdrop		as press_delta	(Brief = "Pressure Drop", DisplayUnit = 'kPa', Symbol ="\Delta P");
	Pdecrease	as press_delta	(Brief = "Pressure Decrease", DisplayUnit = 'kPa', Symbol ="P_{decr}");

	Head 				as energy_mass	(Brief = "Head",Hidden=true);
	HeadIsentropic 		as energy_mass	(Brief = "Isentropic Head");
	Tisentropic			as temperature  (Brief = "Isentropic Temperature"); 
	
	IsentropicEff 	as efficiency 	(Brief = "Isentropic efficiency");
	MechanicalEff 	as efficiency 	(Brief = "Mechanical efficiency");
	
	FluidPower	as power	 	(Brief = "Fluid Power");
	BrakePower	as power	 	(Brief = "Brake Power");
	PowerLoss	as power	 	(Brief = "Power Losses",Lower=0);
	Mwm			as molweight    (Brief = "Mixture Molar Weight");
	rho			as dens_mass    (Brief = "Mass Density");
	Zfac_in		as fraction    	(Brief = "Compressibility factor at inlet");
	Zfac_out 	as fraction    	(Brief = "Compressibility factor at outlet");

in	Inlet 		as stream	(Brief = "Inlet stream", PosX=0.05, PosY=0.0, Symbol="_{in}");
out	Outlet 		as streamPH	(Brief = "Outlet stream", PosX=0.65, PosY=1, Symbol="_{out}");

out	WorkOut		as work_stream	(Brief = "Work Outlet", PosX=1, PosY=0.46);

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 Decrease"
	Outlet.P  = Inlet.P - Pdecrease;

"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 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);

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


if IsentropicEff equal 1

	then
"Discharge Temperature"
	Outlet.T = Tisentropic;

	else

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

end

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

"Brake Power"
	BrakePower = WorkOut.Work;

"Brake Power"
	BrakePower = FluidPower*MechanicalEff;

"Power Loss"
	PowerLoss = BrakePower - FluidPower;

end