source: branches/gui/eml/heat_exchangers/HeatExchangerDetailed.mso @ 636

#*-------------------------------------------------------------------
* 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: Gerson Balbueno Bicca 
* $Id: HeatExchangerDetailed.mso 197 2007-03-08 14:31:57Z bicca $
*------------------------------------------------------------------*#
using "heat_exchangers/HEX_Engine";

Model ShellandTubesBasic

ATTRIBUTES
        Pallete = false;
        Brief  = "Basic Model for Detailed Shell and Tube Heat Exchanger.";
        Info  =
"to be documented.
        
== Assumptions ==
* to be documented

== Specify ==
* to be documented

== Setting Parameters ==
* to be documented

== References ==
[1] E.A.D. Saunders, Heat Exchangers: Selection, Design and
 Construction, Longman, Harlow, 1988. 

[2] Taborek, J., Shell-and-tube heat exchangers, in Heat Exchanger Design Handbook, Vol. 3
 Hemisphere Publishing Corp., New York, 1988. 

[3] Bell, K. J., Mueller, A. C., Wolverine Engineering Data Book II. Wolverine Tube, Inc., <www.wlv.com>, 2001. 

[4] Fakheri, A. , Alternative approach for determining log mean temperature difference correction factor 
 and number of shells of shell and tube heat exchangers, Journal of Enhanced Heat Transfer, v. 10, p. 407- 420, 2003. 

[5] Gnielinski, V., Forced convection in ducts, in Heat Exchanger Design Handbook, Vol. 2
 Hemisphere Publishing Corp., New York, 1988.";

PARAMETERS

HotSide                 as Switcher     (Brief="Hot Side in the Exchanger",Valid=["shell","tubes"],Default="shell");
ShellType       as Switcher     (Brief="TEMA Designation",Valid=["Eshell","Fshell"],Default="Eshell");
Pattern         as Switcher     (Brief="Tube Layout Characteristic Angle",Valid=["Triangle","Rotated Square","Square"],Default="Triangle");

VARIABLES

        Tubes                   as Tube_Side_Main               (Brief="Tube Side Section" , Symbol="^{tube}"); 
        Shell                   as Shell_Side_Main      (Brief="Shell Side Section" , Symbol="^{shell}");       
        Baffles                 as Baffles_Main                         (Brief="Baffle Section", Symbol=" ");
        Clearances      as Clearances_Main      (Brief="Diametral Clearances", Symbol=" ");
        
in  InletTube           as stream                                       (Brief="Inlet Tube Stream", PosX=0.08, PosY=0, Symbol="_{in }^{tube}");
out OutletTube  as streamPH                             (Brief="Outlet Tube Stream", PosX=0.08, PosY=1, Symbol="_{out }^{tube}");
in  InletShell          as stream                                       (Brief="Inlet Shell Stream", PosX=0.2237, PosY=0, Symbol="_{in }^{shell}");
out OutletShell as streamPH                             (Brief="Outlet Shell Stream", PosX=0.8237, PosY=1, Symbol="_{out }^{shell}");
        Details                         as Details_Main                         (Brief="Details in Heat Exchanger", Symbol = " ");
        
#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++#
#                               Auxiliar Variables - Must be hidden                                             
#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++#
        Nc              as Real                                 (Brief = "Number of Tube rows Crossed in one Crossflow Section", Hidden = true, Lower=1);
        Ncw     as Real                                 (Brief = "Number of Effective Crossflow rows in Each Window", Hidden = true, Lower=1);
        a                       as Real                                 (Brief = "Variable for calculating Ji heat transfer correction Factor", Hidden = true, Lower=1e-3);
        b                       as Real                                 (Brief = "Variable for calculating shell side pressure drop friction Factor", Hidden = true, Lower=1e-3);
        Rb              as Real                                 (Brief = "ByPass Correction Factor for Pressure Drop", Hidden = true, Lower=1e-3);
        Rss             as Real                                 (Brief = "Correction Factor for Pressure Drop", Hidden = true, Lower=1e-3);
        Rspd    as Real                                 (Brief = "Pressure Drop Correction Factor for Unequal Baffle Spacing", Hidden = true, Lower=1e-3);
        mw              as Real                                 (Brief = "Mass Velocity in Window Zone", Hidden = true, Unit='kg/m^2/s');
        Ji                      as constant                     (Brief="Shell Side Ji Factor", Symbol ="J_i", Hidden = true, Default=0.05);
        Jr                      as positive                     (Brief="Shell Side Jr Factor",  Symbol ="J_r", Hidden = true, Lower=10e-6);
        Jl                      as positive                     (Brief="Shell Side Jl Factor",  Symbol ="J_l", Hidden = true, Lower=10e-6);
        Jb                      as positive                     (Brief="Shell Side Jb Factor", Symbol ="J_b", Hidden = true, Lower=10e-6);
        Jc                      as positive                     (Brief="Shell Side Jc Factor", Symbol ="J_c", Hidden = true, Lower=10e-6);
        Js                      as positive                     (Brief="Shell Side Js Factor", Symbol ="J_s", Hidden = true, Lower=10e-6);
        Jtotal  as positive                     (Brief="Shell Side Jtotal Factor", Symbol ="J_{total}", Hidden = true, Lower=10e-6);
        Sm              as area                                 (Brief="Shell Side Cross Flow Area", Symbol ="S_m", Hidden = true, Default=0.05,Lower=10e-6);

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

TubeFlowRegime           as Switcher            (Brief="Tube Side Flow Regime ",Valid=["laminar","transition","turbulent"],Default="laminar");
ShellFlowRegime                 as Switcher             (Brief="Shell Side Flow Regime ",Valid=["deep laminar","laminar","turbulent"],Default="deep laminar");
ShellRange                              as Switcher             (Brief="Shell Side Flow Regime Range for Correction Factor",Valid=["range1","range2","range3", "range4","range5"],Default="range1");
Side                                                            as Switcher             (Brief="Flag for Fluid Alocation ",Valid=["shell","tubes"],Default="shell");
LaminarCorrelation      as Switcher             (Brief="Tube Heat Transfer Correlation in Laminar Flow",Valid=["Hausen","Schlunder"],Default="Hausen");
TransitionCorrelation   as Switcher             (Brief="Tube Heat Transfer Correlation in Transition Flow",Valid=["Gnielinski","ESDU"],Default="Gnielinski");
TurbulentCorrelation    as Switcher             (Brief="Tube Heat Transfer Correlation in Turbulent Flow",Valid=["Petukhov","SiederTate"],Default="Petukhov");

#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++#
#                               Auxiliar Parameters     - Must be hidden                                                        
#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++#
Pi                                                      as constant   (Brief="Pi Number", Hidden = true, Default=3.14159265, Symbol = "\pi");
Aonozzle_Shell          as area                 (Brief="Shell Outlet Nozzle Area", Hidden = true, Lower=1E-6 ,  Symbol ="A_{nozzle\_out }^{shell}");
Ainozzle_Shell          as area                 (Brief="Shell Inlet Nozzle Area", Hidden = true, Lower=1E-6 ,  Symbol ="A_{nozzle\_in }^{shell}");
Aeonozzle_Shell         as area                 (Brief="Shell Outlet Escape Area Under Nozzle", Hidden = true, Lower=1E-6 ,  Symbol ="Aescape_{nozzle\_out }^{shell}");
Aeinozzle_Shell         as area                 (Brief="Shell Inlet Escape Area Under Nozzle",Hidden = true, Lower=1E-6 ,  Symbol ="Aescape_{nozzle\_in }^{shell}");
Aonozzle_Tube   as area                 (Brief="Tube Outlet Nozzle Area", Hidden = true, Lower=1E-6 ,  Symbol ="A_{nozzle\_out }^{tube}");
Ainozzle_Tube           as area                 (Brief="Tube Inlet Nozzle Area", Hidden = true, Lower=1E-6 ,  Symbol ="A_{nozzle\_in }^{tube}");
Kinlet_Tube             as positive     (Brief="Tube Inlet Nozzle Pressure Loss Coeff", Hidden = true, Default=1.1, Symbol ="K_{in }^{tube}");
Koutlet_Tube            as positive     (Brief="Tube Outlet Nozzle Pressure Loss Coeff",Hidden = true, Default=0.7, Symbol ="K_{out }^{tube}");
Ods                                             as Real                 (Brief="Baffle cut angle in degrees", Symbol = "\theta _{ds}", Hidden = true);
Octl                                    as Real                 (Brief="Baffle cut angle relative to the centerline in degrees", Symbol = "\theta _{ctl}", Hidden = true);
Ftw                                             as Real                 (Brief="Fraction of number of tubes in baffle window", Symbol = "F _{tw}", Hidden = true);
Scd                                             as area                 (Brief="Shell to baffle leakage area", Symbol = "S _{cd}", Hidden = true);
Std                                             as area                 (Brief="Tube to baffle hole leakage area", Symbol = "S _{td}", Hidden = true);
Rs                                              as Real                 (Brief="Ratio of the shell to baffle leakage area", Symbol = "R_s", Hidden = true);
Dw                                      as length               (Brief="Hydraulic diameter of the baffle window", Symbol = "D _w", Hidden = true);

SET

#"Molecular weight"
        M       = PP.MolecularWeight();
        
#"Pi Number"
        Pi      = 3.14159265;

#"Baffle cut angle in degrees"
        Ods     = (360/Pi)*acos(1-0.02*Baffles.BaffleCut);

#"Baffle cut angle relative to the centerline"
        Octl    = (360/Pi)*acos((Shell.ShellID/(Shell.ShellID - Clearances.BundleToShell - Tubes.TubeOD))*(1-0.02*Baffles.BaffleCut));

#"Fraction of number of tubes in baffle window"
        Ftw     = (Octl/360)-sin(Octl*Pi/180)/(2*Pi);

#"Shell to baffle leakage area"
        Scd     = Pi*Shell.ShellID*Clearances.BaffleToShell *((360-Ods)/720);

#"Tube to baffle hole leakage area"
        Std     = Pi*0.25*((Clearances.TubeToBaffle + Tubes.TubeOD)^2-Tubes.TubeOD*Tubes.TubeOD)*Tubes.NumberOfTubes*(1-Ftw);

#"comments"
        Rs              = Scd/(Scd+Std);

#"comments"
        Dw      = (4*abs((Pi*Shell.ShellID*Shell.ShellID*((Ods/360)-sin(Ods*Pi/180)/(2*Pi))/4)-(Tubes.NumberOfTubes*Pi*Tubes.TubeOD*Tubes.TubeOD*Ftw/4)))/(Pi*Tubes.TubeOD*Tubes.NumberOfTubes*Ftw+ Pi*Shell.ShellID*Ods/360);

#"Tube Side Inlet Nozzle Area"
        Ainozzle_Tube = 0.25*Pi*Tubes.InletNozzleID^2;

#"Tube Side Outlet Nozzle Area"
        Aonozzle_Tube = 0.25*Pi*Tubes.OutletNozzleID^2;

#"Tube Inlet Nozzle Pressure Loss Coeff"
        Kinlet_Tube   = 1.1;

#"Tube Outlet Nozzle Pressure Loss Coeff"
        Koutlet_Tube  = 0.7;

#"Shell Outlet Nozzle Area"
        Aonozzle_Shell  = 0.25*Pi*Shell.OutletNozzleID^2;

#"Shell Inlet Nozzle Area"
        Ainozzle_Shell  = 0.25*Pi*Shell.InletNozzleID^2;

#"Shell Outlet Escape Area Under Nozzle"
        Aeonozzle_Shell = Pi*Shell.OutletNozzleID*Clearances.Honozzle_Shell + 0.6*Aonozzle_Shell*(1-(Tubes.TubeOD/Tubes.TubePitch));

#"Shell Inlet Escape Area Under Nozzle"
        Aeinozzle_Shell = Pi*Shell.InletNozzleID*Clearances.Hinozzle_Shell + 0.6*Ainozzle_Shell*(1-(Tubes.TubeOD/Tubes.TubePitch));

EQUATIONS

"Shell Stream Average Temperature"
        Shell.Properties.Average.T = 0.5*InletShell.T + 0.5*OutletShell.T;
        
"Tube Stream Average Temperature"
        Tubes.Properties.Average.T = 0.5*InletTube.T + 0.5*OutletTube.T;
        
"Shell Stream Average Pressure"
        Shell.Properties.Average.P = 0.5*InletShell.P+0.5*OutletShell.P;
        
"Tube Stream Average Pressure"
        Tubes.Properties.Average.P = 0.5*InletTube.P+0.5*OutletTube.P;
        
"Shell Stream Average Molecular Weight"
        Shell.Properties.Average.Mw = sum(M*InletShell.z);

"Tube Stream Average Molecular Weight"
        Tubes.Properties.Average.Mw = sum(M*OutletTube.z);
        
if InletTube.v equal 0
        
        then    
        
"Tube Stream Average Heat Capacity"
        Tubes.Properties.Average.Cp     =       PP.LiquidCp(Tubes.Properties.Average.T,Tubes.Properties.Average.P,OutletTube.z);

"Tube Stream Average Mass Density"
        Tubes.Properties.Average.rho =  PP.LiquidDensity(Tubes.Properties.Average.T,Tubes.Properties.Average.P,OutletTube.z);

"Tube Stream Inlet Mass Density"
        Tubes.Properties.Inlet.rho      =       PP.LiquidDensity(OutletTube.T,OutletTube.P,OutletTube.z);

"Tube Stream Outlet Mass Density"
        Tubes.Properties.Outlet.rho     =       PP.LiquidDensity(OutletTube.T,OutletTube.P,OutletTube.z);

"TubeStream Average Viscosity"
        Tubes.Properties.Average.Mu     =       PP.LiquidViscosity(Tubes.Properties.Average.T,Tubes.Properties.Average.P,OutletTube.z);

"Tube Stream Average Conductivity"
        Tubes.Properties.Average.K      =       PP.LiquidThermalConductivity(Tubes.Properties.Average.T,Tubes.Properties.Average.P,OutletTube.z);

"Tube Stream Viscosity at Wall Temperature"
        Tubes.Properties.Wall.Mu        =       PP.LiquidViscosity(Tubes.Properties.Wall.Twall,Tubes.Properties.Average.P,OutletTube.z);

        else

"Tube Stream Average Heat Capacity"
        Tubes.Properties.Average.Cp     =       PP.VapourCp(Tubes.Properties.Average.T,Tubes.Properties.Average.P,OutletTube.z);

"Tube Stream Average Mass Density"
        Tubes.Properties.Average.rho =  PP.VapourDensity(Tubes.Properties.Average.T,Tubes.Properties.Average.P,OutletTube.z);

"Tube Stream Inlet Mass Density"
        Tubes.Properties.Inlet.rho      =       PP.VapourDensity(OutletTube.T,OutletTube.P,OutletTube.z);

"Tube Stream Outlet Mass Density"       
        Tubes.Properties.Outlet.rho     =       PP.VapourDensity(OutletTube.T,OutletTube.P,OutletTube.z);

"Tube Stream Average Viscosity "
        Tubes.Properties.Average.Mu     =       PP.VapourViscosity(Tubes.Properties.Average.T,Tubes.Properties.Average.P,OutletTube.z);

"Tube Stream Average Conductivity "
        Tubes.Properties.Average.K      =       PP.VapourThermalConductivity(Tubes.Properties.Average.T,Tubes.Properties.Average.P,OutletTube.z);

"Tube Stream Viscosity at Wall Temperature"
        Tubes.Properties.Wall.Mu        =       PP.VapourViscosity(Tubes.Properties.Wall.Twall,Tubes.Properties.Average.P,OutletTube.z);

end

if InletShell.v equal 0

        then

"Shell Stream Average Heat Capacity"
        Shell.Properties.Average.Cp     =               PP.LiquidCp(Shell.Properties.Average.T,Shell.Properties.Average.P,InletShell.z);

"Shell Stream Average Mass Density"
        Shell.Properties.Average.rho    =               PP.LiquidDensity(Shell.Properties.Average.T,Shell.Properties.Average.P,InletShell.z);

"ShellStream Inlet Mass Density"        
        Shell.Properties.Inlet.rho      =               PP.LiquidDensity(InletShell.T,InletShell.P,InletShell.z);

"Shell Stream Outlet Mass Density"      
        Shell.Properties.Outlet.rho     =               PP.LiquidDensity(OutletShell.T,OutletShell.P,OutletShell.z);

"Shell Stream Average Viscosity"
        Shell.Properties.Average.Mu     =               PP.LiquidViscosity(Shell.Properties.Average.T,Shell.Properties.Average.P,InletShell.z); 

"Shell Stream Average Conductivity"
        Shell.Properties.Average.K      =               PP.LiquidThermalConductivity(Shell.Properties.Average.T,Shell.Properties.Average.P,InletShell.z);       

"ShellStream Viscosity  at Wall Temperature"
        Shell.Properties.Wall.Mu                =               PP.LiquidViscosity(Shell.Properties.Wall.Twall,Shell.Properties.Average.P,InletShell.z);        


        else

"Shell Stream Average Heat Capacity"
        Shell.Properties.Average.Cp     =               PP.VapourCp(Shell.Properties.Average.T,Shell.Properties.Average.P,InletShell.z);

"Shell Stream Average Mass Density"
        Shell.Properties.Average.rho    =               PP.VapourDensity(Shell.Properties.Average.T,Shell.Properties.Average.P,InletShell.z);

"Shell Stream Inlet Mass Density"       
        Shell.Properties.Inlet.rho      =               PP.VapourDensity(InletShell.T,InletShell.P,InletShell.z);

"Shell Stream Outlet Mass Density"
        Shell.Properties.Outlet.rho     =               PP.VapourDensity(OutletShell.T,OutletShell.P,OutletShell.z);

"Shell Stream Average Viscosity"
        Shell.Properties.Average.Mu     =               PP.VapourViscosity(Shell.Properties.Average.T,Shell.Properties.Average.P,InletShell.z);

"Shell Stream Average Conductivity"
        Shell.Properties.Average.K      =               PP.VapourThermalConductivity(Shell.Properties.Average.T,Shell.Properties.Average.P,InletShell.z);       

"Shell Stream Viscosity at Wall Temperature"
        Shell.Properties.Wall.Mu                =               PP.VapourViscosity(Shell.Properties.Wall.Twall,Shell.Properties.Average.P,InletShell.z);

end

switch Side
        
        case "shell":
        
"Energy Balance Hot Stream"
        Details.Q = InletShell.F*(InletShell.h-OutletShell.h);

"Energy Balance Cold Stream"
        Details.Q =-InletTube.F*(InletTube.h-OutletTube.h);

        when InletTube.T > InletShell.T switchto "tubes";

        case "tubes":
        
"Energy Balance Hot Stream"
        Details.Q = InletTube.F*(InletTube.h-OutletTube.h);

"Energy Balance Cold Stream"
        Details.Q =-InletShell.F*(InletShell.h-OutletShell.h);
        
        when InletTube.T < InletShell.T switchto "shell";
        
end

"Flow Mass Inlet Tube Stream"
        Tubes.Properties.Inlet.Fw               =  sum(M*InletTube.z)*InletTube.F;

"Flow Mass Outlet Tube Stream"
        Tubes.Properties.Outlet.Fw      =  sum(M*OutletTube.z)*OutletTube.F;

"Flow Mass Inlet Shell Stream"
        Shell.Properties.Inlet.Fw               =  sum(M*InletShell.z)*InletShell.F;

"Flow Mass Outlet Shell Stream" 
        Shell.Properties.Outlet.Fw              =  sum(M*OutletShell.z)*OutletShell.F;

"Molar Balance Shell Stream"
        OutletShell.F  = InletShell.F;
        
"Molar Balance Tube Stream"
        OutletTube.F = InletTube.F;

"Shell  Stream Molar Fraction Constraint"
        OutletShell.z=InletShell.z;
        
"Tube Stream Molar Fraction Constraint"
        OutletTube.z=InletTube.z;
        
"Jc Factor"
        Jc = 0.55+0.72*(1-2*Ftw);

"Jl Factor"
        Jl = 0.44*(1-Rs)+(1-0.44*(1-Rs))*exp(-2.2*(Scd + Std)/Sm);

"Total J Factor"
        Jtotal = Jc*Jl*Jb*Jr*Js;

"Mass Velocity in Window Zone"
        mw      = Shell.Properties.Inlet.Fw/sqrt(abs(Sm*abs((Pi*Shell.ShellID*Shell.ShellID*((Ods/360)-sin(Ods*Pi/180)/(2*Pi))/4)-(Tubes.NumberOfTubes*Pi*Tubes.TubeOD*Tubes.TubeOD*Ftw/4))));

switch TubeFlowRegime
        
        case "laminar":
        
"Friction Factor for heat Transfer: Not Necessary in Laminar Correlation - Use any one equation that you want"
        Tubes.HeatTransfer.fi   = 16/Tubes.HeatTransfer.Re;
        
"Friction Factor for Pressure Drop in Laminar Flow"
        Tubes.PressureDrop.FricFactor  = 16/Tubes.HeatTransfer.Re;
        
switch LaminarCorrelation
        
        case "Hausen":

"Nusselt Number in Laminar Flow - Hausen Equation"
        Tubes.HeatTransfer.Nu = 3.665 + ((0.19*((Tubes.TubeID/Tubes.TubeLength)*Tubes.HeatTransfer.Re*Tubes.HeatTransfer.PR)^0.8)/(1+0.117*((Tubes.TubeID/Tubes.TubeLength)*Tubes.HeatTransfer.Re*Tubes.HeatTransfer.PR)^0.467));
        
        case "Schlunder":
        
"Nusselt Number in Laminar Flow - Schlunder Equation"
        Tubes.HeatTransfer.Nu = (49.027896+4.173281*Tubes.HeatTransfer.Re*Tubes.HeatTransfer.PR*(Tubes.TubeID/Tubes.TubeLength))^(1/3);

end
        
        when Tubes.HeatTransfer.Re > 2300 switchto "transition";
        
        case "transition":
        
"Friction Factor for heat Transfer : for use in Gnielinski Equation"
        Tubes.HeatTransfer.fi   = 1/(0.79*ln(Tubes.HeatTransfer.Re)-1.64)^2;
        
"Friction Factor for Pressure Drop in Transition Flow"
        Tubes.PressureDrop.FricFactor  = 0.0122;
        
switch TransitionCorrelation
        
        case "Gnielinski":
        
"Nusselt Number in Transition Flow - Gnielinski Equation"
        Tubes.HeatTransfer.Nu*(1+(12.7*sqrt(0.125*Tubes.HeatTransfer.fi)*((Tubes.HeatTransfer.PR)^(2/3) -1))) = 0.125*Tubes.HeatTransfer.fi*(Tubes.HeatTransfer.Re-1000)*Tubes.HeatTransfer.PR;

        case "ESDU":
        
"Nusselt Number in Transition Flow - ESDU Equation"
        Tubes.HeatTransfer.Nu =1;#to be implemented
        
end

        when Tubes.HeatTransfer.Re < 2300 switchto "laminar";
        when Tubes.HeatTransfer.Re > 10000 switchto "turbulent";

        case "turbulent":

"Friction Factor for heat Transfer : for use in Petukhov Equation"
        Tubes.HeatTransfer.fi   = 1/(1.82*log(Tubes.HeatTransfer.Re)-1.64)^2;

"Friction Factor for Pressure Drop in Turbulent Flow"
        Tubes.PressureDrop.FricFactor  = 0.0035 + 0.264*Tubes.HeatTransfer.Re^(-0.42);

switch TurbulentCorrelation
        
        case "Petukhov":
        
"Nusselt Number in Turbulent Flow - Petukhov Equation"
        Tubes.HeatTransfer.Nu*(1.07+(12.7*sqrt(0.125*Tubes.HeatTransfer.fi)*((Tubes.HeatTransfer.PR)^(2/3) -1))) = 0.125*Tubes.HeatTransfer.fi*Tubes.HeatTransfer.Re*Tubes.HeatTransfer.PR;
        
        case "SiederTate":

"Nusselt Number in Transition Flow - Sieder Tate Equation"
        Tubes.HeatTransfer.Nu = 0.027*(Tubes.HeatTransfer.PR)^(1/3)*(Tubes.HeatTransfer.Re)^(4/5);

end
        
        when Tubes.HeatTransfer.Re < 10000 switchto "transition";

end

switch Pattern
        
case "Triangle": 

"Shell Side Cross Flow Area"
        Sm= Baffles.Central_Spacing*(Clearances.BundleToShell+((Shell.ShellID-Clearances.BundleToShell-Tubes.TubeOD)/Tubes.TubePitch)*(Tubes.TubePitch-Tubes.TubeOD));

"Number of Tube rows Crossed in one Crossflow Section"
        Nc      = Shell.ShellID*(1-0.02*Baffles.BaffleCut)/(0.866*Tubes.TubePitch);

"Number of Effective Crossflow rows in Each Window"
        Ncw = 0.8*(Shell.ShellID*0.01*Baffles.BaffleCut-(Clearances.BundleToShell + Tubes.TubeOD)*0.5)/(0.866*Tubes.TubePitch);

"Variable for calculating Ji heat transfer correction Factor"
        a       =       1.45/(1+0.14*Shell.HeatTransfer.Re^0.519);
        
"Variable for calculating Shell Side Pressure Drop Friction Factor"
        b=7/(1+0.14*Shell.HeatTransfer.Re^0.5);

"Correction Factor for Pressure Drop"
        Rss     = Clearances.SealStrip/(Shell.ShellID*(1-0.02*Baffles.BaffleCut)/(0.866*Tubes.TubePitch)) ;
        
"Ideal Shell Side Pressure Drop"
        Shell.PressureDrop.Ideal= 2*Shell.PressureDrop.FricFactor*(Shell.ShellID*(1-0.02*Baffles.BaffleCut)/(0.866*Tubes.TubePitch))*(Shell.Properties.Inlet.Fw/Sm)^2/(Shell.Properties.Average.rho*Shell.HeatTransfer.Phi);

"Shell Pressure End Zones"
        Shell.PressureDrop.EndZones = Shell.PressureDrop.Ideal*(1+ (Ncw/(Shell.ShellID*(1-0.02*Baffles.BaffleCut)/(0.866*Tubes.TubePitch))))*Rb*Rspd;

switch ShellRange
        
        case "range1":
        
"Ji Factor"
        Ji =1.40*((1.33*Tubes.TubeOD/Tubes.TubePitch)^a)*Shell.HeatTransfer.Re^0.667;
        
"Shell Side Pressure Drop Friction Factor"
        Shell.PressureDrop.FricFactor=48*((1.33*Tubes.TubeOD/Tubes.TubePitch)^b)*Shell.HeatTransfer.Re^(-1);
        
        when Shell.HeatTransfer.Re > 10 switchto "range2";
        
        case "range2":
        
"Ji Factor"
        Ji =1.36*((1.33*Tubes.TubeOD/Tubes.TubePitch)^a)*Shell.HeatTransfer.Re^(-0.657);
        
"Shell Side Pressure Drop Friction Factor"
        Shell.PressureDrop.FricFactor=45.10*((1.33*Tubes.TubeOD/Tubes.TubePitch)^b)*Shell.HeatTransfer.Re^(-0.973);
        
        when Shell.HeatTransfer.Re > 100 switchto "range3";
        
        case "range3":

"Ji Factor"
        Ji =0.593*((1.33*Tubes.TubeOD/Tubes.TubePitch)^a)*Shell.HeatTransfer.Re^(-0.477);
        
"Shell Side Pressure Drop Friction Factor"
        Shell.PressureDrop.FricFactor=4.570*((1.33*Tubes.TubeOD/Tubes.TubePitch)^b)*Shell.HeatTransfer.Re^(-0.476);
        
        when Shell.HeatTransfer.Re > 1000 switchto "range4";
        
        case "range4":

"Ji Factor"
        Ji =0.321*((1.33*Tubes.TubeOD/Tubes.TubePitch)^a)*Shell.HeatTransfer.Re^(-0.388);
        
"Shell Side Pressure Drop Friction Factor"
        Shell.PressureDrop.FricFactor=0.486*((1.33*Tubes.TubeOD/Tubes.TubePitch)^b)*Shell.HeatTransfer.Re^(-0.152);

        when Shell.HeatTransfer.Re > 10000 switchto "range5";

        case "range5":

"Ji Factor"
        Ji =0.321*((1.33*Tubes.TubeOD/Tubes.TubePitch)^a)*Shell.HeatTransfer.Re^(-0.388);

"Shell Side Pressure Drop Friction Factor"
        Shell.PressureDrop.FricFactor=0.372*((1.33*Tubes.TubeOD/Tubes.TubePitch)^b)*Shell.HeatTransfer.Re^(-0.123);
        
        when Shell.HeatTransfer.Re < 10000 switchto "range4";
        
end

case "Rotated Square": 

"Shell Side Cross Flow Area"
        Sm= Baffles.Central_Spacing*(Clearances.BundleToShell+((Shell.ShellID-Clearances.BundleToShell-Tubes.TubeOD)/(0.707*Tubes.TubePitch))*(Tubes.TubePitch-Tubes.TubeOD));

"Number of Tube rows Crossed in one Crossflow Section"
        Nc      = Shell.ShellID*(1-0.02*Baffles.BaffleCut)/(0.707*Tubes.TubePitch);

"Number of Effective Crossflow rows in Each Window"
        Ncw = 0.8*(Shell.ShellID*0.01*Baffles.BaffleCut-(Clearances.BundleToShell + Tubes.TubeOD)*0.5)/(0.707*Tubes.TubePitch);

"Variable for calculating Ji heat transfer correction Factor"
        a       =       1.930/(1+0.14*Shell.HeatTransfer.Re^0.500);

"Variable for calculating Shell Side Pressure Drop Friction Factor"
        b=6.59/(1+0.14*Shell.HeatTransfer.Re^0.52);

"Correction Factor for Pressure Drop"
        Rss     = Clearances.SealStrip/(Shell.ShellID*(1-0.02*Baffles.BaffleCut)/(0.707*Tubes.TubePitch)) ;

"Ideal Shell Side Pressure Drop"
        Shell.PressureDrop.Ideal= 2*Shell.PressureDrop.FricFactor*(Shell.ShellID*(1-0.02*Baffles.BaffleCut)/(0.707*Tubes.TubePitch))*(Shell.Properties.Inlet.Fw/Sm)^2/(Shell.Properties.Average.rho*Shell.HeatTransfer.Phi);

"Shell Pressure End Zones"
        Shell.PressureDrop.EndZones = Shell.PressureDrop.Ideal*(1+ (Ncw/(Shell.ShellID*(1-0.02*Baffles.BaffleCut)/(0.707*Tubes.TubePitch))))*Rb*Rspd;

switch ShellRange
        
        case "range1":

"Ji Factor"
        Ji =1.550*((1.33*Tubes.TubeOD/Tubes.TubePitch)^a)*Shell.HeatTransfer.Re^0.667;

"Shell Side Pressure Drop Friction Factor"
        Shell.PressureDrop.FricFactor=32*((1.33*Tubes.TubeOD/Tubes.TubePitch)^b)*Shell.HeatTransfer.Re^(-1);
        
        when Shell.HeatTransfer.Re > 10 switchto "range2";
        
        case "range2":

"Ji Factor"
        Ji =0.498*((1.33*Tubes.TubeOD/Tubes.TubePitch)^a)*Shell.HeatTransfer.Re^0.656;

"Shell Side Pressure Drop Friction Factor"
        Shell.PressureDrop.FricFactor=26.20*((1.33*Tubes.TubeOD/Tubes.TubePitch)^b)*Shell.HeatTransfer.Re^(-0.913);
        
        when Shell.HeatTransfer.Re > 100 switchto "range3";
        
        case "range3":

"Ji Factor"
        Ji =0.730*((1.33*Tubes.TubeOD/Tubes.TubePitch)^a)*Shell.HeatTransfer.Re^0.500;

"Shell Side Pressure Drop Friction Factor"
        Shell.PressureDrop.FricFactor=3.50*((1.33*Tubes.TubeOD/Tubes.TubePitch)^b)*Shell.HeatTransfer.Re^(-0.476);
        
        when Shell.HeatTransfer.Re > 1000 switchto "range4";
        
        case "range4":
        
"Ji Factor"
        Ji =0.370*((1.33*Tubes.TubeOD/Tubes.TubePitch)^a)*Shell.HeatTransfer.Re^(-0.396);
        
"Shell Side Pressure Drop Friction Factor"
        Shell.PressureDrop.FricFactor=0.333*((1.33*Tubes.TubeOD/Tubes.TubePitch)^b)*Shell.HeatTransfer.Re^(-0.136);

        when Shell.HeatTransfer.Re > 10000 switchto "range5";

        case "range5":

"Ji Factor"
        Ji =0.370*((1.33*Tubes.TubeOD/Tubes.TubePitch)^a)*Shell.HeatTransfer.Re^(-0.396);
        
"Shell Side Pressure Drop Friction Factor"
        Shell.PressureDrop.FricFactor=0.303*((1.33*Tubes.TubeOD/Tubes.TubePitch)^b)*Shell.HeatTransfer.Re^(-0.126);
        
        when Shell.HeatTransfer.Re < 10000 switchto "range4";
        
end

case "Square":

"Shell Side Cross Flow Area"
        Sm= Baffles.Central_Spacing*(Clearances.BundleToShell+((Shell.ShellID-Clearances.BundleToShell-Tubes.TubeOD)/Tubes.TubePitch)*(Tubes.TubePitch-Tubes.TubeOD));

"Number of Tube rows Crossed in one Crossflow Section"
        Nc      = Shell.ShellID*(1-0.02*Baffles.BaffleCut)/Tubes.TubePitch;
        
"Number of Effective Crossflow rows in Each Window"
        Ncw = 0.8*(Shell.ShellID*0.01*Baffles.BaffleCut-(Clearances.BundleToShell + Tubes.TubeOD)*0.5)/Tubes.TubePitch;

"Variable for calculating Ji heat transfer correction Factor"
        a       =       1.187/(1+0.14*Shell.HeatTransfer.Re^0.370);

"Variable for calculating Shell Side Pressure Drop Friction Factor"
        b=6.30/(1+0.14*Shell.HeatTransfer.Re^0.38);

"Correction Factor for Pressure Drop"
        Rss     = Clearances.SealStrip/(Shell.ShellID*(1-0.02*Baffles.BaffleCut)/Tubes.TubePitch) ;

"Ideal Shell Side Pressure Drop"
        Shell.PressureDrop.Ideal= 2*Shell.PressureDrop.FricFactor*(Shell.ShellID*(1-0.02*Baffles.BaffleCut)/Tubes.TubePitch)*(Shell.Properties.Inlet.Fw/Sm)^2/(Shell.Properties.Average.rho*Shell.HeatTransfer.Phi);

"Shell Pressure End Zones"
        Shell.PressureDrop.EndZones = Shell.PressureDrop.Ideal*(1+ (Ncw/(Shell.ShellID*(1-0.02*Baffles.BaffleCut)/Tubes.TubePitch)))*Rb*Rspd;

switch ShellRange
        
        case "range1":

"Ji Factor"
        Ji =0.970*((1.33*Tubes.TubeOD/Tubes.TubePitch)^a)*Shell.HeatTransfer.Re^(-0.667);
        
"Shell Side Pressure Drop Friction Factor"      
        Shell.PressureDrop.FricFactor=35*((1.33*Tubes.TubeOD/Tubes.TubePitch)^b)*Shell.HeatTransfer.Re^(-1);

        when Shell.HeatTransfer.Re > 10 switchto "range2";
        
        case "range2":

"Ji Factor"
        Ji =0.900*((1.33*Tubes.TubeOD/Tubes.TubePitch)^a)*Shell.HeatTransfer.Re^(-0.631);

"Shell Side Pressure Drop Friction Factor"      
        Shell.PressureDrop.FricFactor=32.10*((1.33*Tubes.TubeOD/Tubes.TubePitch)^b)*Shell.HeatTransfer.Re^(-0.963);

        when Shell.HeatTransfer.Re > 100 switchto "range3";
        
        case "range3":

"Ji Factor"
        Ji =0.408*((1.33*Tubes.TubeOD/Tubes.TubePitch)^a)*Shell.HeatTransfer.Re^(-0.460);

"Shell Side Pressure Drop Friction Factor"      
        Shell.PressureDrop.FricFactor=6.090*((1.33*Tubes.TubeOD/Tubes.TubePitch)^b)*Shell.HeatTransfer.Re^(-0.602);

        when Shell.HeatTransfer.Re > 1000 switchto "range4";
        
        case "range4":
        
"Ji Factor"
        Ji =0.107*((1.33*Tubes.TubeOD/Tubes.TubePitch)^a)*Shell.HeatTransfer.Re^(-0.266);

"Shell Side Pressure Drop Friction Factor"      
        Shell.PressureDrop.FricFactor=0.0815*((1.33*Tubes.TubeOD/Tubes.TubePitch)^b)*Shell.HeatTransfer.Re^0.022;

        when Shell.HeatTransfer.Re > 10000 switchto "range5";

        case "range5":
        
"Ji Factor"
        Ji =0.370*((1.33*Tubes.TubeOD/Tubes.TubePitch)^a)*Shell.HeatTransfer.Re^(-0.395);

"Shell Side Pressure Drop Friction Factor"      
        Shell.PressureDrop.FricFactor=0.391*((1.33*Tubes.TubeOD/Tubes.TubePitch)^b)*Shell.HeatTransfer.Re^(-0.148);

        when Shell.HeatTransfer.Re < 10000 switchto "range4";
        
end

end

switch ShellFlowRegime

        case "deep laminar":

"Jr Factor"     
        Jr = (10/((Nc +Ncw)*(Baffles.NumberOfBaffles+1)))^0.18;

"Js Factor"
        Js = (Baffles.NumberOfBaffles-1+(Baffles.Inlet_Spacing/Baffles.Central_Spacing)^0.7 + (Baffles.Outlet_Spacing/Baffles.Central_Spacing)^0.7)/(Baffles.NumberOfBaffles-1+(Baffles.Inlet_Spacing/Baffles.Central_Spacing) + (Baffles.Outlet_Spacing/Baffles.Central_Spacing)); 

"Jb Factor"
        Jb =    exp(-1.35*( Clearances.BundleToShell+ Tubes.TubeOD)*Baffles.Central_Spacing/Sm*(1-(2*(Clearances.SealStrip/Nc)^(1/3))));

"ByPass Correction Factor for Pressure Drop"
        Rb      = exp(-4.7*((Clearances.BundleToShell + Tubes.TubeOD)*Baffles.Central_Spacing/Sm)*(1-(2*Rss)^(1/3)));

"Pressure Drop Correction Factor for Unequal Baffle Spacing"
        Rspd = (Baffles.Central_Spacing/Baffles.Outlet_Spacing) + (Baffles.Central_Spacing/Baffles.Inlet_Spacing);

"Shell Pressure Drop Baffle Window"
        Shell.PressureDrop.Window    = Baffles.NumberOfBaffles*((26/Shell.Properties.Average.rho)*mw*Shell.Properties.Average.Mu*(Ncw/(Tubes.TubePitch-Tubes.TubeOD)+ Baffles.Central_Spacing/(Dw*Dw))+ 0.5*mw*mw/Shell.Properties.Average.rho)*exp(-1.33*(1+Rs)*((Scd + Std)/Sm)^(-0.15*(1+Rs) + 0.8));

        when Shell.HeatTransfer.Re > 20 switchto "laminar";

        case "laminar":

"Jr Factor"     
        Jr = (10/((Nc +Ncw)*(Baffles.NumberOfBaffles+1)))^0.18 + (0.25-0.0125*Shell.HeatTransfer.Re)*((10/((Nc +Ncw)*(Baffles.NumberOfBaffles+1)))^0.18 - 1);

"Js Factor"
        Js = (Baffles.NumberOfBaffles-1+(Baffles.Inlet_Spacing/Baffles.Central_Spacing)^0.7 + (Baffles.Outlet_Spacing/Baffles.Central_Spacing)^0.7)/(Baffles.NumberOfBaffles-1+(Baffles.Inlet_Spacing/Baffles.Central_Spacing) + (Baffles.Outlet_Spacing/Baffles.Central_Spacing)); 

"Jb Factor"
        Jb =    exp(-1.35*( Clearances.BundleToShell+ Tubes.TubeOD)*Baffles.Central_Spacing/Sm*(1-(2*(Clearances.SealStrip/Nc)^(1/3))));

"ByPass Correction Factor for Pressure Drop"
        Rb      = exp(-4.7*((Clearances.BundleToShell+ Tubes.TubeOD)*Baffles.Central_Spacing/Sm)*(1-(2*Rss)^(1/3)));

"Pressure Drop Correction Factor for Unequal Baffle Spacing"
        Rspd = (Baffles.Central_Spacing/Baffles.Outlet_Spacing) + (Baffles.Central_Spacing/Baffles.Inlet_Spacing);

"Shell Pressure Drop Baffle Window"
        Shell.PressureDrop.Window    = Baffles.NumberOfBaffles*((26/Shell.Properties.Average.rho)*mw*Shell.Properties.Average.Mu*(Ncw/(Tubes.TubePitch-Tubes.TubeOD)+ Baffles.Central_Spacing/(Dw*Dw))+ 0.5*mw*mw/Shell.Properties.Average.rho)*exp(-1.33*(1+Rs)*((Scd + Std)/Sm)^(-0.15*(1+Rs) + 0.8));

        when Shell.HeatTransfer.Re < 20 switchto "deep laminar";
        when Shell.HeatTransfer.Re > 100 switchto "turbulent";

        case "turbulent":

"Jr Factor"     
        Jr = 1;

"Js Factor"
        Js = (Baffles.NumberOfBaffles-1+(Baffles.Inlet_Spacing/Baffles.Central_Spacing)^0.4 + (Baffles.Outlet_Spacing/Baffles.Central_Spacing)^0.4)/(Baffles.NumberOfBaffles-1+(Baffles.Inlet_Spacing/Baffles.Central_Spacing) + (Baffles.Outlet_Spacing/Baffles.Central_Spacing)); 

"Jb Factor"
        Jb =    exp(-1.25*( Clearances.BundleToShell+ Tubes.TubeOD)*Baffles.Central_Spacing/Sm*(1-(2*(Clearances.SealStrip/Nc)^(1/3))));

"ByPass Correction Factor for Pressure Drop"
        Rb      = exp(-3.7*((Clearances.BundleToShell + Tubes.TubeOD)*Baffles.Central_Spacing/Sm)*(1-(2*Rss)^(1/3)));

"Pressure Drop Correction Factor for Unequal Baffle Spacing"
        Rspd = (Baffles.Central_Spacing/Baffles.Outlet_Spacing)^1.8 + (Baffles.Central_Spacing/Baffles.Inlet_Spacing)^1.8;

"Shell Pressure Drop Baffle Window"
        Shell.PressureDrop.Window    = Baffles.NumberOfBaffles*((2+0.6*Ncw)*0.5*mw*mw/Shell.Properties.Average.rho)*exp(-1.33*(1+Rs)*((Scd + Std)/Sm)^(-0.15*(1+Rs) + 0.8));
        
        when Shell.HeatTransfer.Re < 100 switchto "laminar";
        
end

"Shell Pressure Drop Cross Flow"
        Shell.PressureDrop.CrossFlow= Shell.PressureDrop.Ideal*Rb*(Baffles.NumberOfBaffles-1)*exp(-1.33*(1+Rs)*((Scd + Std)/Sm)^(-0.15*(1+Rs) + 0.8));

"Shell Side Phi correction"
        Shell.HeatTransfer.Phi  = (Shell.Properties.Average.Mu/Shell.Properties.Wall.Mu)^0.14;

"Tube Side Phi correction"
        Tubes.HeatTransfer.Phi  = (Tubes.Properties.Average.Mu/Tubes.Properties.Wall.Mu)^0.14;
        
"Shell Side inlet Nozzle rho-V^2"
        Shell.PressureDrop.RVsquare_in = Shell.Properties.Inlet.rho*(Shell.PressureDrop.Vnozzle_in)^2;

"Shell Side Outlet Nozzle rho-V^2"
        Shell.PressureDrop.RVsquare_out = Shell.Properties.Outlet.rho*(Shell.PressureDrop.Vnozzle_out)^2;

"Tube Side Pressure Drop"
        Tubes.PressureDrop.TubeFriction         = 2*Tubes.PressureDrop.FricFactor*Tubes.TubeLength*Tubes.Properties.Average.rho*(Tubes.HeatTransfer.Vtube^2)*Tubes.Tubepasses/(Tubes.TubeID*Tubes.HeatTransfer.Phi);

"Pressure Drop Tube Side Inlet Nozzle"
        Tubes.PressureDrop.InletNozzle  = 0.5*Kinlet_Tube*Tubes.Properties.Inlet.rho*Tubes.PressureDrop.Vnozzle_in^2;

"Velocity Tube Side Inlet Nozzle"
        Tubes.PressureDrop.Vnozzle_in   = Tubes.Properties.Inlet.Fw/(Tubes.Properties.Inlet.rho*Ainozzle_Tube);

"Pressure Drop Tube Side Outlet Nozzle"
        Tubes.PressureDrop.OutletNozzle = 0.5*Koutlet_Tube*Tubes.Properties.Outlet.rho*Tubes.PressureDrop.Vnozzle_out^2;

"Velocity Tube Side Outlet Nozzle"
        Tubes.PressureDrop.Vnozzle_out  = Tubes.Properties.Inlet.Fw/(Tubes.Properties.Outlet.rho*Aonozzle_Tube);

"Shell Pressure Drop Inlet Nozzle"
        Shell.PressureDrop.InletNozzle  = (0.5*Shell.Properties.Inlet.Fw^2/Shell.Properties.Inlet.rho)*((1/Ainozzle_Shell^2)+(1/Aeinozzle_Shell^2));

"Velocity Shell Side Inlet Nozzle"
        Shell.PressureDrop.Vnozzle_in   = Shell.Properties.Inlet.Fw/(Shell.Properties.Inlet.rho*Ainozzle_Shell);

"Shell Pressure Drop Outlet Nozzle"
        Shell.PressureDrop.OutletNozzle = (0.5*Shell.Properties.Outlet.Fw^2/Shell.Properties.Outlet.rho)*((1/Ainozzle_Shell^2)+(1/Aeinozzle_Shell^2));

"Velocity Shell Side Outlet Nozzle"
        Shell.PressureDrop.Vnozzle_out  = Shell.Properties.Outlet.Fw/(Shell.Properties.Outlet.rho*Aonozzle_Shell);

"Pressure Drop Shell Stream"
        OutletShell.P  = InletShell.P - Shell.PressureDrop.Total;       
        
"Pressure Drop Tube Stream"
        OutletTube.P  = InletTube.P - Tubes.PressureDrop.Total;

"Shell Wall Temperature"
        Shell.Properties.Wall.Twall     = (Shell.Properties.Average.T+Tubes.Properties.Average.T)/2;

"Tube Wall Temperature"
        Tubes.Properties.Wall.Twall  = (Shell.Properties.Average.T+Tubes.Properties.Average.T)/2;

"Tube Side Velocity"
        Tubes.HeatTransfer.Vtube        = Tubes.Properties.Inlet.Fw*Tubes.Tubepasses/((Pi*Tubes.TubeID*Tubes.TubeID/4)*Tubes.Properties.Average.rho*Tubes.NumberOfTubes);

"Tube Side Reynolds Number"
        Tubes.HeatTransfer.Re           = (Tubes.Properties.Average.rho*Tubes.HeatTransfer.Vtube*Tubes.TubeID)/Tubes.Properties.Average.Mu;
        
"Tube Side Prandtl Number"
        Tubes.HeatTransfer.PR           = ((Tubes.Properties.Average.Cp/Tubes.Properties.Average.Mw)*Tubes.Properties.Average.Mu)/Tubes.Properties.Average.K;

"Tube Side Film Coefficient"
        Tubes.HeatTransfer.htube= (Tubes.HeatTransfer.Nu*Tubes.Properties.Average.K/Tubes.TubeID)*Tubes.HeatTransfer.Phi;

"Shell Side Prandtl Number"
        Shell.HeatTransfer.PR           = ((Shell.Properties.Average.Cp/Shell.Properties.Average.Mw)*Shell.Properties.Average.Mu)/Shell.Properties.Average.K;

"Overall Heat Transfer Coefficient Dirty"
        Details.Ud=1/(Tubes.TubeOD/(Tubes.HeatTransfer.htube*Tubes.TubeID)+Shell.Fouling+Tubes.Fouling*(Tubes.TubeOD/Tubes.TubeID)+(Tubes.TubeOD*ln(Tubes.TubeOD/Tubes.TubeID)/(2*Tubes.Kwall))+(1/(Shell.HeatTransfer.hshell)));

"Overall Heat Transfer Coefficient Clean"
        Details.Uc=1/(Tubes.TubeOD/(Tubes.HeatTransfer.htube*Tubes.TubeID)+(Tubes.TubeOD*ln(Tubes.TubeOD/Tubes.TubeID)/(2*Tubes.Kwall))+(1/(Shell.HeatTransfer.hshell)));

"Exchange Surface Area"
        Details.A=Pi*Tubes.TubeOD*Tubes.NumberOfTubes*Tubes.TubeLength;

"Baffle Spacing Constraint"
        Tubes.TubeLength = Baffles.Inlet_Spacing+Baffles.Outlet_Spacing+Baffles.Central_Spacing*(Baffles.NumberOfBaffles-1);

"Shell Side Reynolds Number"
        Shell.HeatTransfer.Re = (Tubes.TubeOD*Shell.Properties.Inlet.Fw/Sm)/Shell.Properties.Average.Mu;

"Shell Heat Transfer Coefficient"
        Shell.HeatTransfer.hshell                       = Ji*(Shell.Properties.Average.Cp/Shell.Properties.Average.Mw)*(Shell.Properties.Inlet.Fw/Sm)*(Shell.HeatTransfer.PR^(-2/3))*Jtotal*Shell.HeatTransfer.Phi;

end 

Model ShellandTubes_NTU         as ShellandTubesBasic

ATTRIBUTES
        Pallete = true;
        Icon    = "icon/ShellandTubes_NTU";     
        Brief  = "Shell and Tubes Heat Exchangers";
        Info  =
        "to be documented";

VARIABLES

Method as NTU_Basic (Brief="NTU Method");

EQUATIONS

"Number of Units Transference"
        Method.NTU*Method.Cmin = Details.Ud*Pi*Tubes.TubeOD*Tubes.NumberOfTubes*Tubes.TubeLength;

"Minimum Heat Capacity"
        Method.Cmin  = min([Method.Ch,Method.Cc]);
        
"Maximum Heat Capacity"
        Method.Cmax  = max([Method.Ch,Method.Cc]);

"Thermal Capacity Ratio"
        Method.Cr    = Method.Cmin/Method.Cmax;
        
switch HotSide
        
        case "shell":

"Duty"
        Details.Q       = Method.Eft*Method.Cmin*(InletShell.T-InletTube.T);

"Hot Stream Heat Capacity"
        Method.Ch  = InletShell.F*Shell.Properties.Average.Cp;
        
"Cold Stream Heat Capacity"
        Method.Cc = InletTube.F*Tubes.Properties.Average.Cp;

        when InletTube.T > InletShell.T switchto "tubes";
        
        case "tubes":

"Duty"
        Details.Q       = Method.Eft*Method.Cmin*(InletTube.T-InletShell.T);

"Hot Stream Heat Capacity"
        Method.Cc = InletShell.F*Shell.Properties.Average.Cp;
        
"Cold Stream Heat Capacity"
        Method.Ch = InletTube.F*Tubes.Properties.Average.Cp;
        
        when InletTube.T < InletShell.T switchto "shell";
        
end

switch ShellType
        
        case "Fshell":
        
"Effectiveness Correction for 2 pass shell side"
        Method.Eft1 = 2*(1+Method.Cr+sqrt(1+Method.Cr^2)*((1+exp(-Method.NTU*sqrt(1+Method.Cr^2)))/(1-exp(-Method.NTU*sqrt(1+Method.Cr^2)))) )^(-1);

"TEMA F Shell Effectiveness"
        Method.Eft = ( ((1-Method.Eft1*Method.Cr)/(1-Method.Eft1))^2 -1  )*( ((1-Method.Eft1*Method.Cr)/(1-Method.Eft1))^2 - Method.Cr )^(-1); 

        case "Eshell":
        
"TEMA E Shell Effectiveness"
        Method.Eft = 2*(1+Method.Cr+sqrt(1+Method.Cr^2)*((1+exp(-Method.NTU*sqrt(1+Method.Cr^2)))/(1-exp(-Method.NTU*sqrt(1+Method.Cr^2)))) )^(-1);
#       Method.Eft = 1;

"Variable not in use when 1 Pass Shell Side"
        Method.Eft1     = 1;
        
end

end

Model ShellandTubes_LMTD        as ShellandTubesBasic

ATTRIBUTES
        Pallete = true;
        Icon    = "icon/ShellandTubes_LMTD";    
        Brief  = "Shell and Tubes Heat Exchangers";
        Info  =
        "to be documented.";

PARAMETERS

LMTDcorrection  as Switcher     (Brief="LMTD Correction Factor Model",Valid=["Bowmann","Fakeri"],Default="Bowmann");
        
VARIABLES

Method  as LMTD_Basic;
R                       as positive     (Brief=" Capacity Ratio for LMTD Correction Fator",Lower=1e-6);
P                       as positive     (Brief="Non - Dimensional Variable for LMTD Correction Fator ",Lower=1e-6);
Pc                      as positive     (Brief="Non - Dimensional Variable for LMTD Correction Fator when 2 Pass Shell Side",Lower=1e-6);
Rho             as positive     (Brief="Non - Dimensional Variable for LMTD Correction Fator in Fakeri Equation",Lower=1e-6);
Phi     as positive     (Brief="Non - Dimensional Variable for LMTD Correction Fator in Fakeri Equation",Lower=1e-6);
lambdaN as positive     (Brief="Non - Dimensional Variable for LMTD Correction Fator in Fakeri Equation when 2 Pass Shell Side",Lower=1e-6);
lambda1 as positive  (Brief="Non - Dimensional Variable for LMTD Correction Fator in Fakeri Equationwhen 2 Pass Shell Side",Lower=1e-6);

EQUATIONS

"Exchange Surface Area"
        Details.Q   = Details.Ud*Pi*Tubes.TubeOD*Tubes.NumberOfTubes*Tubes.TubeLength*Method.LMTD*Method.Fc;

switch HotSide
        
        case "shell":

"Non Dimensional Variable for LMTD Correction Fator in Fakeri Equation "
        Phi*(2*((InletShell.T+ OutletShell.T)-(InletTube.T+ OutletTube.T)))  = (sqrt(((InletShell.T- OutletShell.T)*(InletShell.T- OutletShell.T))+((OutletTube.T - InletTube.T)*(OutletTube.T - InletTube.T))));

"R: Capacity Ratio for LMTD Correction Fator"
        R*(OutletTube.T - InletTube.T ) = (InletShell.T-OutletShell.T);

"P: Non - Dimensional Variable for LMTD Correction Fator"
        P*(InletShell.T- InletTube.T)= (OutletTube.T-InletTube.T);
        
"Temperature Difference at Inlet"
        Method.DT0 = InletShell.T - OutletTube.T;

"Temperature Difference at Outlet"
        Method.DTL = OutletShell.T - InletTube.T;

        when InletTube.T > InletShell.T switchto "tubes";
        
        case "tubes":

"Non Dimensional Variable for LMTD Correction Fator in Fakeri Equation "
        Phi*(2*((InletShell.T+ OutletShell.T)-(InletTube.T+ OutletTube.T)))  = (sqrt(((InletShell.T- OutletShell.T)*(InletShell.T- OutletShell.T))+((OutletTube.T - InletTube.T)*(OutletTube.T - InletTube.T))));

"R: Capacity Ratio for LMTD Correction Fator"
        R*(OutletShell.T - InletShell.T ) = (InletTube.T-OutletTube.T);

"P: Non - Dimensional Variable for LMTD Correction Fator"
        P*(InletTube.T- InletShell.T)= (OutletShell.T-InletShell.T);
        
"Temperature Difference at Inlet"
        Method.DT0 = InletTube.T - OutletShell.T;

"Temperature Difference at Outlet"
        Method.DTL = OutletTube.T - InletShell.T;

        
        when InletTube.T < InletShell.T switchto "shell";
        
end

switch ShellType
        
        case "Fshell":
        
switch LMTDcorrection
        
        case "Bowmann":
        
" Variable not in use with Bowmann equation"
        lambdaN =1;
        
" Variable not in use with Bowmann equation"
        lambda1 =1;

#" Variable not in use with Bowmann equation"
#       Phi = 1;

" Variable not in use with Bowmann equation"
        Rho =1;

if R equal 1
        
        then
        
"Non Dimensional Variable for LMTD Correction Fator when 2 Pass Shell Side"
        Pc*(2-P)= P;

"LMTD Correction Fator when 2 Pass Shell Side"
        Method.Fc= (sqrt(2)*Pc)/((1-Pc)*ln( abs( ( 2-Pc*0.585786)/( 2-Pc*3.414214))));
        
        else
        
"Non Dimensional Variable for LMTD Correction Fator when 2 Pass Shell Side"
        Pc = (sqrt(abs(( 1-P*R)/(1-P)))-1)/(sqrt(abs(( 1-P*R)/(1-P)))-R);

"LMTD Correction Fator when 2 Pass Shell Side"
        Method.Fc = sqrt(R*R+1)*ln(abs((1-Pc*R)/(1-Pc)))/((1-R)*ln( abs( ( 2-Pc*(R+1-sqrt(R*R+1)))/ ( 2-Pc*(R + 1 + sqrt(R*R+1))))));
        
end

        case "Fakeri":
        
" Variable not in use with Fakeri equation"
        Pc = P;
        
"Non Dimensional Variable for LMTD Correction Fator in Fakeri Equation"
        Rho*(1-P*R) = (1-P);

#"Non Dimensional Variable for LMTD Correction Fator in Fakeri Equation "
#       Phi = (sqrt(((Inlet.Hot.T - Outlet.Hot.T)*(Inlet.Hot.T- Outlet.Hot.T))+((Outlet.Cold.T -  Inlet.Cold.T)*(Outlet.Cold.T -  Inlet.Cold.T))))/(2*((Inlet.Hot.T + Outlet.Hot.T)-( Inlet.Cold.T + Outlet.Cold.T)));

if Rho equal 1
        
        then
        
" Variable not in use when Rho = 1"
        lambdaN =       1;
        
" Variable not in use when Rho = 1"
        lambda1 =       1;
        
"LMTD Correction Fator when 2 Pass Shell Side"
        Method.Fc = (2*Phi )/(ln(abs((1+Phi )/(1-Phi ))));
        
        else

"Non Dimensional Variable for LMTD Correction Fator in Fakeri Equation"
        lambdaN = (1/ln(sqrt(abs(Rho))))*((2*sqrt(abs(Rho))-2)/(sqrt(abs(Rho))+1));
        
"Non Dimensional Variable for LMTD Correction Fator in Fakeri Equation"
        lambda1 = (1/ln(abs(Rho)))*((2*Rho-2)/(Rho+1));

"LMTD Correction Fator when 2 Pass Shell Side"
        Method.Fc =     ((2*Phi *(lambdaN/lambda1))/(ln(abs((1+Phi *(lambdaN/lambda1))/(1-Phi *(lambdaN/lambda1))))))*(1/lambdaN);

end


end

        case "Eshell":
        
" Variable not in use when 1 Pass Shell Side"
        lambdaN =1;

" Variable not in use when 1 Pass Shell Side"
        lambda1 =1;
        
" Variable not in use when 1 Pass Shell Side"
        Pc = P;
        
switch LMTDcorrection
        
        case "Bowmann":

#" Variable not in use with Bowmann equation"
#       Phi  = 1;
        
" Variable not in use with Bowmann equation"
        Rho = 1;


 if R equal 1
        
    then
        
"LMTD Correction Fator when 1 Pass Shell Side"
        Method.Fc = (sqrt(2)*P)/((1-P)*ln( abs( ( 2-P*0.585786)/( 2-P*3.414214))));

        else
        
"LMTD Correction Fator when 1 Pass Shell Side"
        Method.Fc = sqrt(R*R+1)*ln(abs((1-P*R)/(1-P)))/((1-R)*ln( abs( ( 2-P*(R+1-sqrt(R*R+1)))/ ( 2-P*(R + 1 + sqrt(R*R+1))))));

end

        case "Fakeri":

#"Non Dimensional Variable for LMTD Correction Fator in Fakeri Equation "
#       Phi  = (sqrt(((Inlet.Hot.T- Outlet.Hot.T)*(Inlet.Hot.T- Outlet.Hot.T))+((Outlet.Cold.T - Inlet.Cold.T)*(Outlet.Cold.T - Inlet.Cold.T))))/(2*((Inlet.Hot.T+ Outlet.Hot.T)-(Inlet.Cold.T+ Outlet.Cold.T)));

"Non Dimensional Variable for LMTD Correction Fator in Fakeri Equation"
        Rho*(1-P*R) = (1-P);

if Rho equal 1
        
        then
        
"LMTD Correction Fator when 1 Pass Shell Side"
        Method.Fc = (4*Phi)/(ln(abs((1+2*Phi)/(1-2*Phi))));

        else

"LMTD Correction Fator when 1 Pass Shell Side"
        Method.Fc = (2*Phi*(Rho+1)*ln(abs(Rho)))/( ln(abs((1+2*Phi)/(1-2*Phi)))*(Rho-1));
        
end

end

        
end

end