source: branches/packed/eml/stage_separators/tray.mso @ 458

#*-------------------------------------------------------------------
* 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 458 2008-02-14 19:09:53Z paula $
*--------------------------------------------------------------------*#

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 packedStage_Navaes as trayBasic
        PARAMETERS
        PPwater as Plugin(Brief="Physical Properties",
                Type="PP",
                Components = [ "water" ],
                LiquidModel = "PR",
                VapourModel = "PR"
        );
        
#       PackingType as Switcher(Valid = ["random", "structured"], Default = "randon");
#       PressureDropModel as Switcher(Valid = ["Leva", "Prahl"], Default = "Prahl");

        a as Real (Brief="Constant used in Leva equation", Default=873.55);
        b as Real (Brief="Constant used in Leva equation", Default=0.058); 
#       Fp as Real (Brief="Packing factor", Default = 300);
        e as fraction (Brief="Packing Porosity", Default=0.84);
        dp as length (Brief="Packing Dimension", Default=0.013);
#       C as Real (Brief="Prahl method constant", Unit = 'kg^0.2*m^1.8/s^2.2', Default = 2.994);

#       S as length (Brief="Structured packing parameter", Default=0.009);
#       teta as Real (Brief="Structured packing parameter", Unit= 'deg', Default=45);
#       C3 as Real (Brief="Structured packing parameter", Default=3.38);

        Across as area (Brief="Tower cross section area");
        Mw(NComp)       as molweight    (Brief = "Component Mol Weight");
        g as acceleration (Default=9.81);

        SET
        Mw = PP.MolecularWeight();
        Ap = Across;
        
        VARIABLES
        rhoL as dens_mass (Brief="Liquid density");
        rhoV as dens_mass (Brief="Vapor density");
        viscL as viscosity (Brief="Liquid Viscosity");
        viscV as viscosity (Brief="Vapor Viscosity");
        rhow as dens_mass (Brief="Water density");
        visclw as viscosity (Brief="Water viscosity");
        
        L as flux_mass (Brief="Liquid mass flux");
        G as flux_mass (Brief="Liquid mass flux");
        Llin as flux_mass (Brief="Water contribution on liquid mass flux");
#       X as Real (Brief="Term in Prahl correlation");
#       Y as Real (Brief="Term in Prahl correlation");
#       Reg as Real (Brief="Packing Reynolds");
#       Ge as velocity (Brief="Temporay variable");
#       Fr as Real (Brief="Froud number");
        phiL as Real (Brief="Liquid holdup in packed towers");
        
#       deltaP_z as Real (Unit = 'inH2O/ft');
        
        EQUATIONS
#       deltaP_z = (InletV.P - OutletV.P) / (V/Across);
        
        "If the liquid is not water - mass flux correction"
        Llin = L * rhow/rhoL;
        
        "Base unit conversion (mol -> mass)"
        L = OutletL.F*sum(Mw*OutletL.z)/Across;
        G = OutletV.F*sum(Mw*OutletV.z)/Across;
        
#       "X in Prahl correlation"
#       X * G = L * (rhoV/rhoL)^0.5;
        
#       "Y in Prahl correlation"
#       Y = G^2 * Fp * (rhow/rhoL) * viscL^0.2 / (rhoV*rhoL*C) ;
        
        "Water Liquid Viscosity"
        visclw = PPwater.LiquidViscosity(OutletL.T, OutletL.P, 1);
        "Water Liquid Density"
        rhow = PPwater.LiquidDensity(OutletL.T, OutletL.P, 1);
        "Liquid Viscosity"
        viscL = PP.LiquidViscosity(OutletL.T, OutletL.P, OutletL.z);
        "Vapor Viscosity"
        viscV = PP.VapourViscosity(OutletV.T, OutletV.P, OutletV.z);
        "Liquid Density"
        rhoL = PP.LiquidDensity(OutletL.T, OutletL.P, OutletL.z);
        "Vapour Density"
        rhoV = PP.VapourDensity(InletV.T, InletV.P, InletV.z);
        
#       "Froud number"
#       Fr = (L/rhoL)^2 / S/g;
#       "Reynolds number"
#       Reg = S*(G/rhoV/(e*sin(teta)))*rhoV/viscV;
#       "Temporary variable"
#       Ge = G/rhoV /(e*sin(teta));
        "Conversion from ML to phiL"
        phiL = ML*vL / V;

#       switch PackingType
#               case "random":
#                       switch PressureDropModel
#                               case "Leva":
                                        (InletV.P - OutletV.P)/'Pa' / (V/'m^3'/(Across/'m^2') ) = a * 10^(b*Llin/'kg/m^2/s') * (G/('kg/m^2/s'))^2/(rhoV/('kg/m^3'));
                                        #(InletV.P - OutletV.P) / (V/(Across) ) =  a * 10^(b*Llin) * (G)^2/(rhoV);
#                               case "Prahl":
#                                       (InletV.P - OutletV.P)/'0.03937*inH2O' = (V/Across)/'m' * Y*(1116*X+500)/(1-Y*(35*X+3));
#                       end
                        phiL = (1.53e-4 + (2.9e-5*e*(dp*L/(viscL*e))^0.66 * (viscL/visclw)^0.75)) * (dp/'m')^(-1.2);
#*              case "structured":
                        (InletV.P - OutletV.P)/'Pa'= (V/Across)/'m' * ( (0.171 + 92.7/Reg) * (rhoV/('kg/m^3')*(Ge/('m/s'))^2/(S/'m')) )
                                                   * (1/(1-C3 * sqrt(Fr) ))^5;
                
                        phiL = C3 * sqrt(Fr);
        end
*#
end

Model packedStage_Billet as trayBasic
        PARAMETERS
        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");
        Across as area;
        ds as length (Brief="Column diameter");
        d as length (Brief="size of an element of packing");
        #h as length (Brief="Height of packing");
        C as Real (Brief="Constant for resitance factor equation"); #Billet pp 80 (Cf+Cfl)/2
        Cp as Real (Brief="Constant for resitance at loading point factor equation"); # Billet pp94
        Mw(NComp)       as molweight    (Brief = "Component Mol Weight");

        VARIABLES
        niL as viscosity (Brief="Liquid dynamic viscosity", DisplayUnit='kg/m/s');
        niV as viscosity (Brief="Vapor dynamic viscosity", DisplayUnit='kg/m/s');
        rhoL as dens_mass;
        rhoV as dens_mass;
        hL as Real (Brief="Liquid holdup", Default = 0.424);
        VL as volume (Brief="Liquid volume", Default = 0.025);
        uL as velocity (Brief="volume flow rate of liquid, m^3/m^2/s", Default = 0.007);
        uV as velocity (Brief="volume flow rate of vapor, m^3/m^2/s", Default = 1.14);
        ksi as Real (Brief="Coefficient of Resistance", Default = 0.784);
        ksil as Real (Brief="Coefficient of Resistance", Default = 0.032);
        Rev as Real(Brief="Vapor Reynolds",Default = 0.966);
        hLs as Real(Default = 0.037);
        hs as length (Brief="Height of the packing stage");
        
        SET
        Mw = PP.MolecularWeight();
        Ap = Across;
        
        EQUATIONS
        "Liquid Density"
        rhoL = PP.LiquidDensity(OutletL.T, OutletL.P, OutletL.z);
        "Vapour Density"
        rhoV = PP.VapourDensity(InletV.T, InletV.P, InletV.z);
        "Liquid viscosity"
        niL = PP.LiquidViscosity(OutletL.T, OutletL.P, OutletL.z);
        "Vapour viscosity"
        niV = PP.VapourViscosity(InletV.T, InletV.P, InletV.z);

        "Liquid volume"
        VL = vL * ML;
        "Liquid holdup"
        hL = VL/V;

        "Volume flow rate of liquid, m^3/m^2/s"
        uL * Across = OutletL.F * vL;
        "Volume flow rate of vapor, m^3/m^2/s"
        uV * Across = OutletV.F * vV;
        
        "Coefficient of Resistance"
        ksi * C^2 * (uL/uV * sqrt(rhoV/rhoL) * (niL/niV)^2)^0.5 = g/1*'s^2/m';
        #ksil = Cp * (exp(uL*rhoL/a/niL/200)*(hL/hLs)^0.3) * (64/Rev+(1.8/Rev)) *
        ksil = Cp * (exp(uL*rhoL/a/niL/200)*(hL/hLs)^0.3) * (64/Rev+(1.8/Rev)) *
                                        ((e-hL)/e)^1.5;
        
#       "Liquid holdup and Liquid flow"
#       a^2 * niL * uL = hL^1 *(g*rhoL/3 - ksi*a*rhoV*uV^2/(4*hL*(e-hL)^2));

#       "Pressure drop and Vapor flow"
#       (InletV.P - OutletV.P)/hs = ksil *(a/2 + 2/ds)*(uV^2*rhoV/(e-hL)^3);
        
        "Vapor Reynolds number"
        Rev = uV * (d-2*hL/a) * rhoV/ niV;

        "Theoretical Liquid Holdup"
        hLs = (12*a^2*niL*uL/g/rhoL)^0.333;
        #hLs = (12*a^2*niL*uL/g/rhoL);
end

Model packedStage_BilletSchultes as trayBasic
        PARAMETERS
        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");
        ds as length (Brief="Column diameter");
        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");
        
        VARIABLES
        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;
        uL as velocity (Brief="volume flow rate of liquid, m^3/m^2/s", Default = 0.007);
        uV as velocity (Brief="volume flow rate of vapor, m^3/m^2/s", Default = 1.14);
        dp as length (Brief="Particle diameter", Default=1e-3);
        invK as Real (Brief="Wall factor");
        Rev as Real (Brief="Reynolds number of the vapor stream", Lower = 0, Default=100);
        Qsio as Real (Brief="Resistance coefficient", Lower = 0);
        
        SET
        Mw = PP.MolecularWeight();
        
        EQUATIONS
        "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);

        "Volume flow rate of liquid, m^3/m^2/s"
        uL * Ap = OutletL.F * vL;
        "Volume flow rate of vapor, m^3/m^2/s"
        uV * Ap = OutletV.F * vV;
        
        "Liquid holdup and Liquid flow"
        vL * ML = (12*miL*a^2*uL/rhoL/g)^1/3 * hs * Ap;
        
        "Particle diameter"
        dp = 6 * (1-e)/a;
        
        "Wall Factor"
        invK = (1 + (2*dp/(3*ds*(1-e))));
        
        "Reynolds number of the vapor stream"
        Rev*invK = dp*uV*rhoV / (miV*(1-e));
        
        "Resistance Coefficient"
        Qsio = Cpo * (64/Rev + 1.8/Rev^0.08);

        "Pressure drop and Vapor flow"
        (InletV.P - OutletV.P)/hs  = Qsio*a*uV^2*rhoV*invK / (2*e^3);
        
        "Efficiency"
        Emv = 1;
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


FlowSheet test
        PARAMETERS
        a as Real (Brief="surface area per packing volume", Unit='m^2/m^3');
#       N as Real (Brief="Number of elements per volume",Unit='1/m^3');
        niL as Real (Brief="Liquid dynamic viscosity", Unit='kg/m/s');
        niV as Real (Brief="Vapor dynamic viscosity", Unit='kg/m/s');
        g as acceleration;
        rhoL as dens_mass;
        rhoV as dens_mass;
        e as Real (Brief="Void fraction of packing, m^3/m^3");
        V as volume;
        Across as area;
        ds as length (Brief="Column diameter");
        d as length (Brief="size of an element of packing");
        h as length (Brief="Height of packing");
        C as Real (Brief="Constant for resitance factor equation");
        Cp as Real (Brief="Constant for resitance at loading point factor equation");
        
        vL as volume_mol;
        vV as volume_mol;
        ML as mol;
        Mw as molweight;
        dP as pressure (DisplayUnit='atm');
        
        VARIABLES
        hL as Real (Brief="Liquid holdup", Default = 0.424);
        VL as volume (Brief="Liquid volume", Default = 0.025);
        uL as velocity (Brief="volume flow rate of liquid, m^3/m^2/s", Default = 0.007);
        uV as velocity (Brief="volume flow rate of vapor, m^3/m^2/s", Default = 1.14);
#       n as Real;
        FV as flow_mol(Default = 149);
        FL as flow_mol(Default = 222);
        ksi as Real (Brief="Coefficient of Resistance", Default = 0.784);
        ksil as Real (Brief="Coefficient of Resistance", Default = 0.032);
        Rev as Real(Default = 0.966);
        hLs as Real(Default = 0.037);
        
        EQUATIONS
        VL = vL * ML;
        hL = VL/V;
        uL * Across = FL * vL;
        uV * Across = FV * vV;
        
        ksi * C^2 * (uL/uV * sqrt(rhoV/rhoL) * (niL/niV)^5.8)^3 = g/1*'s^2/m';
        
        a^2 * niL * uL = hL^1 *(g*rhoL/3 - ksi*a*rhoV*uV^2/(4*hL*(e-hL)^2));
        
        dP/h = ksil *(a/2 + 2/ds)*(uV^2*rhoV/(e-hL)^3);
        
        ksil = Cp * (exp(uL*rhoL/a/niL/200)*(hL/hLs)^0.3) * (64/Rev+(1.8/Rev)) *
                                ((e-hL)/e);#1.5
        
        Rev = uV * (d-2*hL/a) * rhoV/ niV;
        
        hLs = (12*a^2*niL*uL/g/rhoL)^0.333;

        SPECIFY
#       FV = 147.1 * 'kmol/h';
#       FL = 229.5 * 'kmol/h';
#       ksi = 0.809623;
        
        SET
        Mw = 75 * 'g/mol';
        vL = 9.5e-5 * 'm^3/mol';
        vV = 0.022 * 'm^3/mol';
        niL = 0.00032 * 'kg/m/s';
        niV = 8.2e-5 * 'kg/m/s';
        rhoL = 809 * 'kg/m^3';
        rhoV  = 4.63 * 'kg/m^3';
        ML = 0.268 * 'kmol';
        dP = 0.1984 * 0.001 * 'atm';#0.1984 * 'atm';
        
        V = 0.06 * 'm^3';#0.06 * 'm^3';
        Across = 0.8 * 'm^2';
        h = 0.075 * 'm';
        ds = 1.009 * 'm';
        d = 50 * 'mm';

#       ksi = 0.8;
        C = 2.37;
        Cp = 0.662;
        e = 0.78;
        a = 120 * 'm^2/m^3';
#       N = 6400 * '1/m^3';

        OPTIONS
        GuessFile = "/home/paula/test.rlt";
        
end