#*-------------------------------------------------------------------
* 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: flash.mso 310 2007-07-13 21:28:33Z arge $
*--------------------------------------------------------------------*#

using "streams";

Model flash
	ATTRIBUTES
	Pallete 	= true;
	Icon 		= "icon/Flash"; 
	Brief 		= "Model of a dynamic flash.";
	Info 		=
	"Assumptions:
	 * both phases are perfectly mixed.
	
	Specify: 
	 * the feed stream;
	 * the outlet flows: OutletV.F and OutletL.F.

	Initial Conditions:
	 * the flash initial temperature (OutletL.T);
	 * the flash initial level (Level);
	 * (NoComps - 1) OutletL (OR OutletV) compositions.
	";
	
	PARAMETERS
	outer PP as Plugin (Brief = "External Physical Properties", Type="PP");
	outer NComp as Integer (Brief = "Number of chemical components", Lower = 1); 
	V as volume (Brief="Total Volume of the flash");
	Mw(NComp) as molweight;
	orientation as Switcher (Valid=["vertical","horizontal"],Default="vertical");
	diameter as length (Brief="Vessel diameter");

	SET
	Mw=PP.MolecularWeight();

	VARIABLES
	in	Inlet as stream(Brief="Feed Stream");
	out	OutletL as liquid_stream(Brief="Liquid outlet stream");
	out	OutletV as vapour_stream(Brief="Vapour outlet stream");
	in	InletQ as energy_stream (Brief="Rate of heat supply");

	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="liquid height");
	Across as area (Brief="Flash Cross section area");

	EQUATIONS
	"Component Molar Balance"
	diff(M)=Inlet.F*Inlet.z - OutletL.F*OutletL.z - OutletV.F*OutletV.z;
	
	"Energy Balance"
	diff(E) = Inlet.F*Inlet.h - OutletL.F*OutletL.h - OutletV.F*OutletV.h + InletQ.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;
	"Mol fraction normalisation"
	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, OutletV.z)*OutletV.z;
	
	"Thermal Equilibrium"
	OutletV.T = OutletL.T;
	
	"Mechanical Equilibrium"
	OutletV.P = OutletL.P;
	
	"Geometry Constraint"
	V = ML * vL + MV * vV;

	switch orientation
	case "vertical":
	"Cross Section Area"
		Across = 0.5 * asin(1) * diameter^2;
	
	"Liquid Level"
		ML * vL = Across * Level;

	case "horizontal":
	"Cylindrical Side Area"
		Across = 0.25*diameter^2 * (asin(1) - asin((diameter - 2*Level)/diameter)) + 
				(Level - 0.5*diameter)*sqrt(Level*(diameter - Level));

	"Liquid Level"
		0.5 * asin(1) * diameter^2 * ML* vL = Across * V;
	end
end

#*----------------------------------------------------------------------
* Model of a  Steady State flash
*---------------------------------------------------------------------*# 
Model flash_steady
	ATTRIBUTES
	Pallete 	= true;
	Icon 		= "icon/Flash"; 
	Brief 		= "Model of a Steady State flash.";
	Info 		=
	"Assumptions:
	 * both phases are perfectly mixed.
	
	Specify: 
	 * the feed stream;
	 * the outlet pressure (OutletV.P);
	 * the outlet temperature OR the heat supplied.
	";
	
	PARAMETERS
	outer PP as Plugin(Brief = "External Physical Properties", Type="PP");
	
	VARIABLES
	in	Inlet as stream(Brief="Feed Stream");
	out	OutletL as liquid_stream(Brief="Liquid outlet stream");
	out	OutletV as vapour_stream(Brief="Vapour outlet stream");
	in	InletQ as energy_stream (Brief="Rate of heat supply"); 
	vfrac as fraction;

	EQUATIONS
	"The flash calculation"
	[vfrac, OutletL.z, OutletV.z] = PP.Flash(OutletV.T, OutletV.P, Inlet.z);
	
	"Global Molar Balance"
	Inlet.F = OutletV.F + OutletL.F;
	"Vaporisation Fraction"
	OutletV.F = Inlet.F * vfrac;
	
	"Energy Balance"
	Inlet.F*Inlet.h  + InletQ.Q = OutletL.F*OutletL.h + OutletV.F*OutletV.h;
	
	"Thermal Equilibrium"
	OutletV.T = OutletL.T;
	
	"Mechanical Equilibrium"
	OutletV.P = OutletL.P;
end