#*-------------------------------------------------------------------
* 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: Paula B. Staudt
* $Id: tray.mso 507 2008-04-28 19:17:48Z arge $
*--------------------------------------------------------------------*#

using "streams";

Model trayBasic
	ATTRIBUTES
	Pallete 	= false;
	Icon 		= "icon/Tray"; 
	Brief 		= "Basic equations of a tray column model.";
	Info 		=
"This model contains only the main equations of a column tray equilibrium model without
the hidraulic equations.
	
== Assumptions ==
* both phases (liquid and vapour) exists all the time;
* thermodymanic equilibrium with Murphree plate efficiency;
* no entrainment of liquid or vapour phase;
* no weeping;
* the dymanics in the downcomer are neglected.
";
	
	PARAMETERS
outer PP as Plugin(Brief = "External Physical Properties", Type="PP");
outer NComp as Integer;
	V as volume(Brief="Total Volume of the tray");
	Q as heat_rate (Brief="Rate of heat supply"); 
	Ap as area (Brief="Plate area = Atray - Adowncomer");
	
	VARIABLES
in	Inlet as stream (Brief="Feed stream", PosX=0, PosY=0.4932, Symbol="_{in}");
in	InletL as stream (Brief="Inlet liquid stream", PosX=0.5195, PosY=0, Symbol="_{inL}");
in	InletV as stream (Brief="Inlet vapour stream", PosX=0.4994, PosY=1, Symbol="_{inV}");
out	OutletL as liquid_stream (Brief="Outlet liquid stream", PosX=0.8277, PosY=1, Symbol="_{outL}");
out	OutletV as vapour_stream (Brief="Outlet vapour stream", PosX=0.8043, PosY=0, Symbol="_{outV}");

	M(NComp) as mol (Brief="Molar Holdup in the tray");
	ML as mol (Brief="Molar liquid holdup");
	MV as mol (Brief="Molar vapour holdup");
	E as energy (Brief="Total Energy Holdup on tray");
	vL as volume_mol (Brief="Liquid Molar Volume");
	vV as volume_mol (Brief="Vapour Molar volume");
	Level as length (Brief="Height of clear liquid on plate");
	yideal(NComp) as fraction;
	Emv as Real (Brief = "Murphree efficiency");
	
	EQUATIONS
	"Component Molar Balance"
	diff(M)=Inlet.F*Inlet.z + InletL.F*InletL.z + InletV.F*InletV.z
		- OutletL.F*OutletL.z - OutletV.F*OutletV.z;
	
	"Energy Balance"
	diff(E) = ( Inlet.F*Inlet.h + InletL.F*InletL.h + InletV.F*InletV.h
		- OutletL.F*OutletL.h - OutletV.F*OutletV.h + Q );
	
	"Molar Holdup"
	M = ML*OutletL.z + MV*OutletV.z;
	
	"Energy Holdup"
	E = ML*OutletL.h + MV*OutletV.h - OutletL.P*V;
	
	"Mol fraction normalisation"
	sum(OutletL.z)= 1.0;
	sum(OutletL.z)= sum(OutletV.z);
	
	"Liquid Volume"
	vL = PP.LiquidVolume(OutletL.T, OutletL.P, OutletL.z);
	"Vapour Volume"
	vV = PP.VapourVolume(OutletV.T, OutletV.P, OutletV.z);
	
	"Chemical Equilibrium"
	PP.LiquidFugacityCoefficient(OutletL.T, OutletL.P, OutletL.z)*OutletL.z = 
		PP.VapourFugacityCoefficient(OutletV.T, OutletV.P, yideal)*yideal;

	"Murphree Efficiency"
	OutletV.z = Emv * (yideal - InletV.z) + InletV.z;
	
	"Thermal Equilibrium"
	OutletV.T = OutletL.T;
	
	"Mechanical Equilibrium"
	OutletV.P = OutletL.P;
	
	"Geometry Constraint"
	V = ML* vL + MV*vV;
	
	"Level of clear liquid over the weir"
	Level = ML*vL/Ap;
end

Model tray as trayBasic
	ATTRIBUTES
	Pallete 	= false;
	Icon 		= "icon/Tray"; 
	Brief 		= "Complete model of a column tray.";
	Info 		=
"== Specify ==
* the Feed stream
* the Liquid inlet stream
* the Vapour inlet stream
* the Vapour outlet flow (OutletV.F)
	
== Initial ==
* the plate temperature (OutletL.T)
* the liquid height (Level) OR the liquid flow OutletL.F
* (NoComps - 1) OutletL compositions
";	

	PARAMETERS
	Ah as area (Brief="Total holes area");
	lw as length (Brief="Weir length");
	g as acceleration (Default=9.81);
	hw as length (Brief="Weir height");
	beta as fraction (Brief="Aeration fraction");
	alfa as fraction (Brief="Dry pressure drop coefficient");
	
	VapourFlow as Switcher(Valid = ["on", "off"], Default = "on");
	LiquidFlow as Switcher(Valid = ["on", "off"], Default = "on");
	
	VARIABLES
	rhoL as dens_mass;
	rhoV as dens_mass;

	EQUATIONS
	"Liquid Density"
	rhoL = PP.LiquidDensity(OutletL.T, OutletL.P, OutletL.z);
	"Vapour Density"
	rhoV = PP.VapourDensity(InletV.T, InletV.P, InletV.z);

	switch LiquidFlow
		case "on":
		"Francis Equation"
#		OutletL.F*vL = 1.84*'m^0.5/s'*lw*((Level-(beta*hw))/(beta))^1.5;
		OutletL.F*vL = 1.84*'1/s'*lw*((Level-(beta*hw))/(beta))^2;
		when Level < (beta * hw) switchto "off";
		
		case "off":
		"Low level"
		OutletL.F = 0 * 'mol/h';
		when Level > (beta * hw) + 1e-6*'m' switchto "on";
	end

	switch VapourFlow
		case "on":
		InletV.F*vV = sqrt((InletV.P - OutletV.P)/(rhoV*alfa))*Ah;
		when InletV.F < 1e-6 * 'kmol/h' switchto "off";
		
		case "off":
		InletV.F = 0 * 'mol/s';
		when InletV.P > OutletV.P + Level*g*rhoL + 1e-1 * 'atm' switchto "on";
	end

end

#*-------------------------------------------------------------------
* Model of a tray with reaction
*-------------------------------------------------------------------*#
Model trayReact
	ATTRIBUTES
	Pallete 	= false;
	Icon 		= "icon/Tray"; 
	Brief 		= "Model of a tray with reaction.";
	Info 		=
"== Assumptions ==
* both phases (liquid and vapour) exists all the time;
* thermodymanic equilibrium with Murphree plate efficiency;
* no entrainment of liquid or vapour phase;
* no weeping;
* the dymanics in the downcomer are neglected.
	
== Specify ==
* the Feed stream;
* the Liquid inlet stream;
* the Vapour inlet stream;
* the Vapour outlet flow (OutletV.F);
* the reaction related variables.
	
== Initial ==
* the plate temperature (OutletL.T)
* the liquid height (Level) OR the liquid flow OutletL.F
* (NoComps - 1) OutletL compositions
";

	PARAMETERS
	outer PP as Plugin(Type="PP");
	outer NComp as Integer;
	V as volume(Brief="Total Volume of the tray");
	Q as power (Brief="Rate of heat supply"); 
	Ap as area (Brief="Plate area = Atray - Adowncomer");
	
	Ah as area (Brief="Total holes area");
	lw as length (Brief="Weir length");
	g as acceleration (Default=9.81);
	hw as length (Brief="Weir height");
	beta as fraction (Brief="Aeration fraction");
	alfa as fraction (Brief="Dry pressure drop coefficient");

	stoic(NComp) as Real(Brief="Stoichiometric matrix");
	Hr as energy_mol;
	Pstartup as pressure;
	
	VapourFlow as Switcher(Valid = ["on", "off"], Default = "off");
	LiquidFlow as Switcher(Valid = ["on", "off"], Default = "off");
	
	VARIABLES
in	Inlet as stream (Brief="Feed stream", PosX=0, PosY=0.4932, Symbol="_{in}");
in	InletL as stream (Brief="Inlet liquid stream", PosX=0.5195, PosY=0, Symbol="_{inL}");
in	InletV as stream (Brief="Inlet vapour stream", PosX=0.4994, PosY=1, Symbol="_{inV}");
out	OutletL as liquid_stream (Brief="Outlet liquid stream", PosX=0.8277, PosY=1, Symbol="_{outL}");
out	OutletV as vapour_stream (Brief="Outlet vapour stream", PosX=0.8043, PosY=0, Symbol="_{outV}");

	yideal(NComp) as fraction;
	Emv as Real (Brief = "Murphree efficiency");

	M(NComp) as mol (Brief="Molar Holdup in the tray");
	ML as mol (Brief="Molar liquid holdup");
	MV as mol (Brief="Molar vapour holdup");
	E as energy (Brief="Total Energy Holdup on tray");
	vL as volume_mol (Brief="Liquid Molar Volume");
	vV as volume_mol (Brief="Vapour Molar volume");
	Level as length (Brief="Height of clear liquid on plate");
	Vol as volume;
	
	rhoL as dens_mass;
	rhoV as dens_mass;
	r3 as reaction_mol (Brief = "Reaction resulting ethyl acetate", DisplayUnit = 'mol/l/s');
	C(NComp) as conc_mol (Brief = "Molar concentration", Lower = -1); #, Unit = "mol/l");
	
	EQUATIONS
	"Molar Concentration"
	OutletL.z = vL * C;
	
	"Reaction"
	r3 = exp(-7150*'K'/OutletL.T)*(4.85e4*C(1)*C(2) - 1.23e4*C(3)*C(4))*'l/mol/s';
	
	"Component Molar Balance"
	diff(M)=Inlet.F*Inlet.z + InletL.F*InletL.z + InletV.F*InletV.z
		- OutletL.F*OutletL.z - OutletV.F*OutletV.z + stoic*r3*ML*vL;
	
	"Energy Balance"
	diff(E) = ( Inlet.F*Inlet.h + InletL.F*InletL.h + InletV.F*InletV.h
		- OutletL.F*OutletL.h - OutletV.F*OutletV.h + Q ) + Hr * r3 * vL*ML;
	
	"Molar Holdup"
	M = ML*OutletL.z + MV*OutletV.z;
	
	"Energy Holdup"
	E = ML*OutletL.h + MV*OutletV.h - OutletL.P*V;
	
	"Mol fraction normalisation"
	sum(OutletL.z)= 1.0;
	
	"Liquid Volume"
	vL = PP.LiquidVolume(OutletL.T, OutletL.P, OutletL.z);
	"Vapour Volume"
	vV = PP.VapourVolume(OutletV.T, OutletV.P, OutletV.z);

	"Thermal Equilibrium"
	OutletV.T = OutletL.T;
	
	"Mechanical Equilibrium"
	OutletV.P = OutletL.P;
	
	"Level of clear liquid over the weir"
	Level = ML*vL/Ap;

	Vol = ML*vL;
	
	"Liquid Density"
	rhoL = PP.LiquidDensity(OutletL.T, OutletL.P, OutletL.z);
	"Vapour Density"
	rhoV = PP.VapourDensity(InletV.T, InletV.P, InletV.z);

	switch LiquidFlow
		case "on":
		"Francis Equation"
		OutletL.F*vL = 1.84*'1/s'*lw*((Level-(beta*hw)+1e-6*'m')/(beta))^2;
		when Level < (beta * hw) switchto "off";
		
		case "off":
		"Low level"
		OutletL.F = 0 * 'mol/h';
		when Level > (beta * hw) + 1e-6*'m' switchto "on";
	end

	switch VapourFlow
		case "on":
		#InletV.P = OutletV.P + Level*g*rhoL + rhoV*alfa*(InletV.F*vV/Ah)^2;
		InletV.F*vV = sqrt((InletV.P - OutletV.P - Level*g*rhoL + 1e-8 * 'atm')/(rhoV*alfa))*Ah;
		when InletV.P < OutletV.P + Level*g*rhoL switchto "off";
		
		case "off":
		InletV.F = 0 * 'mol/s';
		when InletV.P > OutletV.P + Level*g*rhoL + 3e-2 * 'atm' switchto "on";
		#when InletV.P > OutletV.P + Level*beta*g*rhoL + 1e-2 * 'atm' switchto "on";
	end

	"Chemical Equilibrium"
	PP.LiquidFugacityCoefficient(OutletL.T, OutletL.P, OutletL.z)*OutletL.z = 
		PP.VapourFugacityCoefficient(OutletV.T, OutletV.P, yideal)*yideal;
	
	OutletV.z = Emv * (yideal - InletV.z) + InletV.z;
	
	sum(OutletL.z)= sum(OutletV.z);
	
	"Geometry Constraint"
	V = ML* vL + MV*vV;
end

#*-------------------------------------
* Model of a packed column stage
-------------------------------------*#
Model packedStage
	ATTRIBUTES
	Pallete 	= false;
	Icon 		= "icon/Tray"; 
	Brief 		= "Complete model of a packed column stage.";
	Info 		=
"== Specify ==
* the Feed stream
* the Liquid inlet stream
* the Vapour inlet stream
* the stage pressure drop (deltaP)
	
== Initial ==
* the plate temperature (OutletL.T)
* the liquid molar holdup ML
* (NoComps - 1) OutletL compositions
";	
	
	PARAMETERS
outer PP as Plugin(Brief = "External Physical Properties", Type="PP");
outer NComp as Integer;
	PPwater	as Plugin(Brief="Physical Properties",
		Type="PP",
		Components = [ "water" ],
		LiquidModel = "PR",
		VapourModel = "PR"
	);

	V as volume(Brief="Total Volume of the tray");
	Q as heat_rate (Brief="Rate of heat supply"); 
	d as length (Brief="Column diameter");	

	a as Real (Brief="surface area per packing volume", Unit='m^2/m^3');
	g as acceleration;
	e as Real (Brief="Void fraction of packing, m^3/m^3");
	Cpo as Real (Brief="Constant for resitance equation"); # Billet and Schultes, 1999.
	Mw(NComp)  	as molweight 	(Brief = "Component Mol Weight");
	hs as length (Brief="Height of the packing stage");
	Qsil as positive (Brief="Resistance coefficient on the liquid load", Default=1);

	VARIABLES
in	Inlet as stream (Brief="Feed stream", PosX=0, PosY=0.4932, Symbol="_{in}");
in	InletL as stream (Brief="Inlet liquid stream", PosX=0.5195, PosY=0, Symbol="_{inL}");
in	InletV as stream (Brief="Inlet vapour stream", PosX=0.4994, PosY=1, Symbol="_{inV}");
out	OutletL as liquid_stream (Brief="Outlet liquid stream", PosX=0.8277, PosY=1, Symbol="_{outL}");
out	OutletV as vapour_stream (Brief="Outlet vapour stream", PosX=0.8043, PosY=0, Symbol="_{outV}");

	M(NComp) as mol (Brief="Molar Holdup in the tray", Default=0.01, Lower=0, Upper=100);
	ML as mol (Brief="Molar liquid holdup", Default=0.01, Lower=0, Upper=100);
	MV as mol (Brief="Molar vapour holdup", Default=0.01, Lower=0, Upper=100);
	E as energy (Brief="Total Energy Holdup on tray", Default=-500);
	vL as volume_mol (Brief="Liquid Molar Volume");
	vV as volume_mol (Brief="Vapour Molar volume");
	
	miL as viscosity (Brief="Liquid dynamic viscosity", DisplayUnit='kg/m/s');
	miV as viscosity (Brief="Vapor dynamic viscosity", DisplayUnit='kg/m/s');
	rhoL as dens_mass;
	rhoV as dens_mass;
	
	deltaP as pressure;
	
	uL as velocity (Brief="volume flow rate of liquid, m^3/m^2/s", Lower=-10, Upper=100);
	uV as velocity (Brief="volume flow rate of vapor, m^3/m^2/s", Lower=-10, Upper=100);
	dp as length (Brief="Particle diameter", Default=1e-3, Lower=0, Upper=10);
	invK as positive (Brief="Wall factor", Default=1, Upper=10);
	Rev as Real (Brief="Reynolds number of the vapor stream", Default=4000);
	Al as area (Brief="Area occupied by the liquid", Default=0.001, Upper=1);
	hl as positive (Brief="Column holdup", Unit='m^3/m^3', Default=0.01,Upper=10);

	SET
	Mw = PP.MolecularWeight();

	EQUATIONS
	"Component Molar Balance"
	diff(M)=Inlet.F*Inlet.z + InletL.F*InletL.z + InletV.F*InletV.z
		- OutletL.F*OutletL.z - OutletV.F*OutletV.z;

	"Energy Balance"
	diff(E) = ( Inlet.F*Inlet.h + InletL.F*InletL.h + InletV.F*InletV.h
		- OutletL.F*OutletL.h - OutletV.F*OutletV.h + Q );
	
	"Molar Holdup"
	M = ML*OutletL.z + MV*OutletV.z;
	
	"Energy Holdup"
	E = ML*OutletL.h + MV*OutletV.h - OutletL.P*V;
	
	"Mol fraction normalisation"
	sum(OutletL.z)= 1.0;
	
	"Liquid Volume"
	vL = PP.LiquidVolume(OutletL.T, OutletL.P, OutletL.z);
	"Vapour Volume"
	vV = PP.VapourVolume(OutletV.T, OutletV.P, OutletV.z);
	
	"Chemical Equilibrium"
	PP.LiquidFugacityCoefficient(OutletL.T, OutletL.P, OutletL.z)*OutletL.z = 
		PP.VapourFugacityCoefficient(OutletV.T, OutletV.P, OutletV.z)*OutletV.z;
	
	"Thermal Equilibrium"
	OutletV.T = OutletL.T;
	
	"Mechanical Equilibrium"
	OutletL.P = OutletV.P;
	
	"Geometry Constraint"
	V*e = ML*vL + MV*vV;
	
	"Liquid Density"
	rhoL = PP.LiquidDensity(OutletL.T, OutletL.P, OutletL.z);
	"Vapour Density"
	rhoV = PP.VapourDensity(InletV.T, InletV.P, InletV.z);
	"Liquid viscosity"
	miL = PP.LiquidViscosity(OutletL.T, OutletL.P, OutletL.z);
	"Vapour viscosity"
	miV = PP.VapourViscosity(InletV.T, InletV.P, InletV.z);

	"Area occupied by the liquid"
	Al = ML*vL/hs;

	"Volume flow rate of liquid, m^3/m^2/s"
	uL * Al = OutletL.F * vL;
	"Volume flow rate of vapor, m^3/m^2/s"
	uV * ((d^2*3.14159/4)*e - Al) = OutletV.F * vV;
	
	"Liquid holdup"
	hl = ML*vL/V/e;
	
	"Particle diameter"
	dp = 6 * (1-e)/a;
	
	"Wall Factor"
	invK = (1 + (2*dp/(3*d*(1-e))));
	
	"Reynolds number of the vapor stream"
	Rev*invK = dp*uV*rhoV / (miV*(1-e));
	
	deltaP = InletV.P - OutletV.P;
	
	"Pressure drop and Vapor flow"
	deltaP/hs  = Qsil*a*uV^2*rhoV*invK / (2*(e-hl)^3);

	"Liquid holdup"
	hl = (12*miL*a^2*uL/rhoL/g)^1/3;
	
	
end

#*-------------------------------------
* Nonequilibrium Model
-------------------------------------*#
Model interface
	
	ATTRIBUTES
	Pallete 	= false;
	Icon 		= "icon/Tray"; 
	Brief 		= "Basic equations of a tray column model.";
	Info 		=
"This model contains only the main equations of a column tray nonequilibrium model without
the hidraulic equations.";

	PARAMETERS
outer PP as Plugin(Brief = "External Physical Properties", Type="PP");
outer NComp as Integer;
outer NC1 as Integer;
	
	VARIABLES
	NL(NComp) as flux_mol 	(Brief = "Stream Molar Flux Rate on Liquid Phase");
	NV(NComp) as flux_mol 	(Brief = "Stream Molar Flux Rate on Vapour Phase");
	T as temperature 		(Brief = "Stream Temperature");
	P as pressure 			(Brief = "Stream Pressure");
	x(NComp) as fraction	(Brief = "Stream Molar Fraction on Liquid Phase");
	y(NComp) as fraction	(Brief = "Stream Molar Fraction on Vapour Phase");
	a as area 			    (Brief = "Interface Area");
	htL as heat_trans_coeff (Brief = "Heat Transference Coefficient on Liquid Phase");
	htV as heat_trans_coeff (Brief = "Heat Transference Coefficient on Vapour Phase");	
	E_liq as heat_flux      (Brief = "Liquid Energy on interface");
    E_vap as heat_flux      (Brief = "Vapour Energy on interface");	
	hL as enth_mol 	       	(Brief = "Liquid Molar Enthalpy");
	hV as enth_mol 	       	(Brief = "Vapour Molar Enthalpy");
	kL(NC1,NC1) as velocity (Brief = "Mass Transfer Coefficients");
	kV(NC1,NC1) as velocity (Brief = "Mass Transfer Coefficients");
	
	EQUATIONS
	"Liquid Enthalpy"
	hL = PP.LiquidEnthalpy(T, P, x);
	
	"Vapour Enthalpy"
	hV = PP.VapourEnthalpy(T, P, y);

end

Model trayRate 
	ATTRIBUTES
	Pallete 	= false;
	Icon 		= "icon/Tray"; 
	Brief 		= "Basic equations of a tray column model.";
	Info 		=
"This model contains only the main equations of a column tray nonequilibrium model without
the hidraulic equations.
	
== Assumptions ==
* both phases (liquid and vapour) exists all the time;
* no entrainment of liquid or vapour phase;
* no weeping;
* the dymanics in the downcomer are neglected.
";
	
	PARAMETERS
outer PP as Plugin(Brief = "External Physical Properties", Type="PP");
outer NComp as Integer;
    NC1 as Integer;
	V as volume(Brief="Total Volume of the tray");
	Q as heat_rate (Brief="Rate of heat supply"); 
	Ap as area (Brief="Plate area = Atray - Adowncomer");
	
	VARIABLES
in	Inlet as stream (Brief="Feed stream", PosX=0, PosY=0.4932, Symbol="_{in}");
in	InletFV as stream (Brief="Feed stream", PosX=0, PosY=0.4932, Symbol="_{in}");
in	InletL as stream (Brief="Inlet liquid stream", PosX=0.5195, PosY=0, Symbol="_{inL}");
in	InletV as stream (Brief="Inlet vapour stream", PosX=0.4994, PosY=1, Symbol="_{inV}");
out	OutletL as liquid_stream (Brief="Outlet liquid stream", PosX=0.8277, PosY=1, Symbol="_{outL}");
out	OutletV as vapour_stream (Brief="Outlet vapour stream", PosX=0.8043, PosY=0, Symbol="_{outV}");

	M_liq(NComp) as mol (Brief="Liquid Molar Holdup in the tray");
	M_vap(NComp) as mol (Brief="Vapour Molar Holdup in the tray");
	ML as mol (Brief="Molar liquid holdup");
	MV as mol (Brief="Molar vapour holdup");
	E_liq as energy (Brief="Total Liquid Energy Holdup on tray");
	E_vap as energy (Brief="Total Vapour Energy Holdup on tray");
	vL as volume_mol (Brief="Liquid Molar Volume");
	vV as volume_mol (Brief="Vapour Molar volume");
	Level as length (Brief="Height of clear liquid on plate");
	interf as interface;	
	
	EQUATIONS
	"Component Molar Balance"
	diff(M_liq)=Inlet.F*Inlet.z + InletL.F*InletL.z 
	- OutletL.F*OutletL.z + interf.a*interf.NL;
	
	diff(M_vap)=InletFV.F*InletFV.z + InletV.F*InletV.z 
	- OutletV.F*OutletV.z - interf.a*interf.NV;
	
	"Energy Balance"
	diff(E_liq) = Inlet.F*Inlet.h + InletL.F*InletL.h
		- OutletL.F*OutletL.h  + Q + interf.a*interf.E_liq;
	
	diff(E_vap) = InletFV.F*InletFV.h + InletV.F*InletV.h
		- OutletV.F*OutletV.h  - interf.a*interf.E_vap;
	
	"Molar Holdup"
	M_liq = ML*OutletL.z;
	
	M_vap = MV*OutletV.z;
	
	"Energy Holdup"
	E_liq = ML*(OutletL.h - OutletL.P*vL);
	
	E_vap = MV*(OutletV.h - OutletV.P*vV);
	
	"Energy on interface"
	interf.E_liq = interf.htL*(interf.T-OutletL.T)+sum(interf.NL)*interf.hL;	
	
	interf.E_vap = interf.htV*(OutletV.T-interf.T)+sum(interf.NV)*interf.hV;
	
	"Mass Conservation"
	interf.NL=interf.NV;
	
	"Energy Conservation"
	interf.E_liq = interf.E_vap;
	
	"Mol fraction normalisation"
	sum(OutletL.z)= 1.0;
	sum(OutletL.z)= sum(OutletV.z);
	sum(interf.x)=1.0;
	sum(interf.x)=sum(interf.y);
	
	"Liquid Volume"
	vL = PP.LiquidVolume(OutletL.T, OutletL.P, OutletL.z);
	"Vapour Volume"
	vV = PP.VapourVolume(OutletV.T, OutletV.P, OutletV.z);
	
	"Chemical Equilibrium"
	PP.LiquidFugacityCoefficient(interf.T, interf.P, interf.x)*interf.x = 
		PP.VapourFugacityCoefficient(interf.T, interf.P, interf.y)*interf.y;

	"Geometry Constraint"
	V = ML*vL + MV*vV;
	
	"Level of clear liquid over the weir"
	Level = ML*vL/Ap;

	"Total Mass Transfer Fluxes"
	interf.NL(1:NC1)=sumt(interf.kL*(interf.x(1:NC1)-OutletL.z(1:NC1)))/vL+
		OutletL.z(1:NC1)*sum(interf.NL);
	
	interf.NV(1:NC1)=sumt(interf.kV*(OutletV.z(1:NC1)-interf.y(1:NC1)))/vV+
		OutletV.z(1:NC1)*sum(interf.NV);

	"Mechanical Equilibrium"
	OutletV.P = OutletL.P;
	interf.P=OutletL.P;
	
	SET   
	NC1=NComp-1;
end