#*-------------------------------------------------------------------
* 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 393 2007-10-17 23:50:09Z arge $
*--------------------------------------------------------------------*#

using "streams";

Model centrifugal_compressor
	ATTRIBUTES
	Pallete 	= true;
	Icon 		= "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=1e-3); 
	Cp        	as cp_mol		(Brief = "Heat Capacity");
	Cv 			as cv_mol 		(Brief = "Heat Capacity");
	Pratio	 	as positive		(Brief = "Pressure Ratio", Symbol ="P_{ratio}");	
	Pdrop		as press_delta	(Brief = "Pressure Drop", DisplayUnit = 'kPa', Symbol ="\Delta P");
	Wp 			as energy_mol	(Brief = "Politropic Head");
	Ws 			as energy_mol	(Brief = "Isentropic Head");
	Tiso		as temperature  (Brief = "Isentropic Temperature"); 
	Effp  		as positive 	(Brief = "Politropic efficiency");
	Effs 		as efficiency 	(Brief = "Isentropic efficiency");
	FPower		as power	 	(Brief = "Fluid Power");
	Mwm			as molweight    (Brief = "Mixture Molar Weight");
in	Inlet 		as stream		(Brief = "Inlet stream", PosX=0, PosY=0.5086, Symbol="_{in}");
out	Outlet 		as streamPH		(Brief = "Outlet stream", PosX=1, PosY=0.5022, Symbol="_{out}");

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

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

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

	"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);
	PP.VapourEntropy(Tiso, Outlet.P, Outlet.z) = 
		PP.VapourEntropy(Inlet.T, Inlet.P, Inlet.z);

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

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