#*-------------------------------------------------------------------
* 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: Estefane Horn, Núbia do Carmo Ferreira
*$Id: valve.mso 920 2010-02-26 17:20:34Z rafael $									
*-------------------------------------------------------------------*#

using "streams";
	
#*-------------------------------------------------------------------
* Model of a valve (simplified)
*-------------------------------------------------------------------- 
*
* Author: Paula B. Staudt
*--------------------------------------------------------------------*#
Model valve_simplified
	ATTRIBUTES
	Pallete 	= true;
	Icon 		= "icon/Valve"; 
	Brief 		= "Model of a very simple valve - used in distillation column models.";
	Info 		=
"== Assumptions ==
* no flashing liquid in the valve;
* the flow in the valve is adiabatic;
* dynamics in the valve are neglected;
* linear flow type.
	
== Specify ==
* the inlet stream
* the plug position (x) OR outlet temperature (Outlet.T) OR outlet pressure (Outlet.P) 
	
	OR		
	
* the inlet stream excluding its flow (Inlet.F)
* the outlet pressure (Outlet.P) OR outlet flow (Outlet.F)
* the plug position (x)
";

	PARAMETERS
outer PP as Plugin(Type="PP");
outer NComp as Integer;
	
	VARIABLES
in	Inlet 	as stream	(Brief = "Inlet stream", PosX=0, PosY=0.7365, Symbol="_{in}");
out	Outlet 	as streamPH	(Brief = "Outlet stream", PosX=1, PosY=0.7365, Symbol="_{out}");
	x as fraction (Brief="Plug Position");
	rho as dens_mass (Brief="Fluid Density", Default=1e3);
	v as vol_mol (Brief="Specific volume", Default=1e3);
	Pdrop	  as press_delta (Brief = "Pressure Drop", DisplayUnit = 'kPa', Symbol ="\Delta P");
	Pratio 	as positive	(Brief = "Pressure Ratio", Symbol ="P_{ratio}");	

	PARAMETERS
	rho_ref as dens_mass (Brief="Reference Density", Default=1e4);
	k as Real (Brief="Valve Constant", Unit='gal/min/psi^0.5');

	EQUATIONS
	"Overall Molar Balance"
	Inlet.F = Outlet.F;
	
	"Componente Molar Balance"
	Inlet.z = Outlet.z;
	
	"Energy Balance"
	Inlet.h = Outlet.h;

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

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

	"Density"
	rho = Inlet.v*PP.VapourDensity((Inlet.T+Outlet.T)/2, (Inlet.P+Outlet.P)/2, Outlet.z) +
		(1-Inlet.v)*PP.LiquidDensity((Inlet.T+Outlet.T)/2, (Inlet.P+Outlet.P)/2, Outlet.z);

	"Volume"
	v = Inlet.v*PP.VapourVolume((Inlet.T+Outlet.T)/2, (Inlet.P+Outlet.P)/2, Outlet.z) +
		(1-Inlet.v)*PP.LiquidVolume((Inlet.T+Outlet.T)/2, (Inlet.P+Outlet.P)/2, Outlet.z);

	if Pdrop > 0 * 'atm' then
		"Flow"
		Outlet.F * v = k*x*sqrt(Pdrop * rho_ref / rho ) ;
	else
		"Closed"
		Outlet.F = 0 * 'kmol/h';
	end
end

Model valve_flow

ATTRIBUTES
	Pallete = true;
	Icon 	= "icon/Valve"; 
	Brief 	= "Model of a very simple valve for setting the flow with a controller.";
	Info 	=
"== ASSUMPTIONS ==
* nothing happens in this valve

== SET ==
* MinFlow: the Minimum Flow Allowable in the valve;
* MaxFlow: the Maximum Flow Allowable in the valve;

== SPECIFY ==
* the Inlet stream
* the FlowFraction (the model requires an inlet signal, also you can use a controller for setting the FlowFraction)
";

PARAMETERS
	outer PP 		as Plugin	(Brief = "External Physical Properties", Type="PP");
	outer NComp 	as Integer 	(Brief="Number of Components");

	MinFlow as flow_mol(Brief="Minimum Flow Allowable in the valve", Default=0);
	MaxFlow as flow_mol(Brief="Maximum Flow Allowable in the valve", Default=1000);
	
VARIABLES

in	Inlet 			as stream	(Brief ="Inlet stream", PosX=0, PosY=0.7365, Symbol="_{in}",Protected=true);
out	Outlet 			as stream	(Brief ="Outlet stream", PosX=1, PosY=0.7365, Symbol="_{out}",Protected=true);
in	FlowFraction 	as control_signal (Brief ="Flow Signal", PosX=0.5, PosY=0,Protected=true);
	
EQUATIONS
"Overall Molar Balance"
	Outlet.F = Inlet.F;

"Temperature"
	Outlet.T = Inlet.T;

"Pressure"
	Outlet.P = Inlet.P;

"Energy Balance"
	Outlet.h = Inlet.h;

"Vapour fraction"
	Outlet.v = Inlet.v;

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

"Flow computation"
	Outlet.F = MinFlow + FlowFraction*(MaxFlow-MinFlow);

end

Model valve

	ATTRIBUTES
	Pallete 	= true;
	Icon 		= "icon/Valve"; 
	Brief 	= "Model of a valve.";
	Info 		=
"== Model of valves ==
* Linear;
* Parabolic;
* Equal;
* Quick;
* Hyperbolic.
	
== Assumptions ==
* First Order Dynamic;
* Only Liquid or Only Vapour;
* Isentalpic.
	
== Specify ==
* the valve type;
* the Valve Coefficient (Cv);
* the valve time constant (Tau).
";

PARAMETERS

outer PP   			as Plugin 	(Brief = "External Physical Properties", Type = "PP");
outer NComp   	as Integer	(Brief = "Number of chemical components", Lower = 1);

	ValveType 	as Switcher 		(Valid = ["linear", "parabolic", "equal", "quick", "hyperbolic"], Default = "linear");
	ValidPhases	as Switcher		(Brief = "Valid Phases for Flash Calculation", Valid = ["Vapour-Only", "Liquid-Only"], Default="Liquid-Only");
#	Tau		    	as time_sec 		(Brief="valve time constant");
	rho60F 			as dens_mass		(Brief = "Water Mass Density at 60 F",Hidden=true);	

VARIABLES
	W as flow_mass(DisplayUnit='kg/s');
	Pdrop			as press_delta		(Brief = "Pressure Drop", DisplayUnit = 'kPa', Symbol ="\Delta P");
	Fvol				as flow_vol			(Brief = "Volumetric Flow");
	fc 				as positive			(Brief = "Opening Function",Hidden=true);
	Cv 				as Real 				(Brief="Valve Flow Coefficient", Unit='gal/min/psi^0.5');
	Cv1 				as Real 				(Brief="Valve Flow Coefficient", Unit='m^2');
	Cg				as Real 				(Brief="Valve Gas Flow Coefficient", Unit='ft^3/h/psi');
	C				as Real 				(Brief="Liquid-gas Coefficient Ratio", Unit='(ft^3/gal)*(min/h)/(psi^.5)');
	StemPosition	as fraction 			(Brief = "Actual valve stem position");
	a as Real;
	#b as Real (Brief="d", Unit='1/(psi^.5)');
	vm				as vol_mol			(Brief = "Mixture Molar Volume");
	rho 				as dens_mass 		(Brief = "Mixture Mass Density");	
#	vsp 				as fraction 			(Brief = "Valve stem position",Hidden=true);
	
in		Inlet 	as stream			(Brief = "Inlet stream", PosX=0, PosY=0.7365, Symbol="_{in}");
out	Outlet 	as streamPH		(Brief = "Outlet stream", PosX=1, PosY=0.7365, Symbol="_{out}");
#in		vsignal	as fraction 		(Brief = "Flow Signal", PosX=0.5, PosY=0);

SET

	rho60F = 984.252	* 'kg/m^3';
	
EQUATIONS

#"First order valve dynamics"
#	Tau*diff(StemPosition) = vsp-StemPosition;

#"Flow Signal"
#	vsp = vsignal;

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

"Enthalpy Balance"
	Outlet.h = Inlet.h;
	
"Molar Balance"
	Outlet.F = Inlet.F;
	
"Outlet Composition"
	Outlet.z = Inlet.z;
	
	Cv1=Cv*'1/(gal/min/psi^0.5)'*2.3837e-5*'m^2';

switch ValidPhases
		
#############################################################

	case "Liquid-Only":
	
if Pdrop > 0 * 'atm' then

"Valve Equation - Liquid Flow"
	Fvol = fc*(Cv/sqrt(1/rho60F))*sqrt(Pdrop/rho);
	"Liquid-gas Coefficient Ratio"
	C*Cv=Cg;
a=1/(1.6764e-2*C*'1/((ft^3/gal)*(min/h)/(psi^.5))')*sqrt(Pdrop/Inlet.P); 	
else

"Valve Equation - Liquid Flow"
	Fvol = fc*(Cv/sqrt(1/rho60F))*sqrt(Pdrop/rho);
	"Liquid-gas Coefficient Ratio"
	C*Cv=Cg;
a=1/(1.6764e-2*C*'1/((ft^3/gal)*(min/h)/(psi^.5))')*sqrt(Pdrop/Inlet.P); 
end
	
"Liquid Mass Density"
	rho = PP.LiquidDensity(Inlet.T,Inlet.P,Inlet.z);

"Liquid Molar Volume"
	vm = PP.LiquidVolume(Inlet.T,Inlet.P,Inlet.z);
	

	
############################################################

	case "Vapour-Only":
	
if Pdrop > 0 * 'atm' then #Update for gas flow !!!!
	
"Liquid-gas Coefficient Ratio"
	C*Cv=Cg;
	a=1/(1.6764e-2*C*'1/((ft^3/gal)*(min/h)/(psi^.5))')*sqrt(Pdrop/Inlet.P); 

	if 1.5708 > a then
	"Valve Equation - Vapour Flow"
		#Fvol = fc*Cg*sqrt(Inlet.P/1000*rho60F/rho);####rho60f/rho ok!!!!
		#Fvol = fc*Cv*sqrt(Pdrop/1000*rho60F/rho);
		#W = fc*Cv1*sqrt(Pdrop/1000*rho);
		Fvol = fc*0.13446*'psi^.5'*Cg*sqrt(Inlet.P/1000*rho60F/rho)*sin(a*'rad');
		
	else
	"Valve Equation - Vapour Flow"
		Fvol = fc*0.13446*Cv*sqrt(Inlet.P*rho60F/rho);
	end
else

"Valve Equation - Vapour Flow"
	Fvol = fc*(Cv/sqrt(1/rho60F))*sqrt(Pdrop/rho);

"Liquid-gas Coefficient Ratio"
	C*Cv=Cg;
	a=1/(1.6764e-2*C*'1/((ft^3/gal)*(min/h)/(psi^.5))')*sqrt(Pdrop/Inlet.P); 
end
	
"Vapour Mass Density"
	rho = PP.VapourDensity(Inlet.T,Inlet.P,Inlet.z);
	#rho=3.708741*'kg/m^3';
"Vapour Molar Volume"
	vm = PP.VapourVolume(Inlet.T,Inlet.P,Inlet.z);
	
end

######################################################

"Calculate Mass Flow"
	Fvol = Inlet.F*vm;
	
	W=Fvol*rho;
	
	
switch ValveType #Update the valve Type
	
	case "linear":

		"Opening Equation"
		fc = StemPosition;

	case "parabolic":

		"Opening Equation"
		fc = StemPosition^2;

	case "equal":

		"Opening Equation"
		fc = StemPosition^2/(2-StemPosition^4)^(1/2);

	case "quick":
	
		"Opening Equation"
		fc = 10*StemPosition/sqrt(1+99*StemPosition^2);

	case "hyperbolic":

		"Opening Equation"
		fc = 0.1*StemPosition/sqrt(1-0.99*StemPosition^2);

	end

end