#*------------------------------------------------------------------- * 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 Tubes Heat Exchangers"; Info = "to be documented."; 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"); VARIABLES in InletTube as stream (Brief="Inlet Tube Stream", PosX=0, PosY=0.4915); out OutletTube as streamPH (Brief="Outlet Tube Stream", PosX=1, PosY=0.4915); in InletShell as stream (Brief="Inlet Shell Stream", PosX=0.5237, PosY=1); out OutletShell as streamPH (Brief="Outlet Shell Stream", PosX=0.5237, PosY=0); Details as Details_Main (Brief="Details in Heat Exchanger"); Tubes as Tube_Side_Main (Brief="Tube Side"); Shell as Shell_Side_Main (Brief="Shell Side"); Baffles as Baffles_Main (Brief="Baffles"); #+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++# # Auxiliar Variables - Must be hidden #+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++# Nc as Real (Brief = "Number of Tube rows Crossed in one Crossflow Section",Lower=1); Ncw as Real (Brief = "Number of Effective Crossflow rows in Each Window",Lower=1); a as Real (Brief = "Variable for calculating Ji heat transfer correction Factor",Lower=1e-3); b as Real (Brief = "Variable for calculating shell side pressure drop friction Factor",Lower=1e-3); Rb as Real (Brief = "ByPass Correction Factor for Pressure Drop",Lower=1e-3); Rss as Real (Brief = "Correction Factor for Pressure Drop",Lower=1e-3); Rspd as Real (Brief = "Pressure Drop Correction Factor for Unequal Baffle Spacing",Lower=1e-3); mw as Real (Brief = "Mass Velocity in Window Zone", Unit='kg/m^2/s'); PARAMETERS outer PP as Plugin (Brief="External Physical Properties",Type = "PP"); outer NComp as Integer (Brief="Number of Components"); Pi as constant (Brief="Pi Number",Default=3.14159265); 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"); #+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++# # Shell Geometrical Parameters #+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++# Tpass as Integer (Brief="Number of Tube Passes",Lower=1); Nss as Integer (Brief="Number of Sealing Strips pairs",Lower=1); Dishell as length (Brief="Inside Shell Diameter",Lower=10e-6); Donozzle_Shell as length (Brief="Shell Outlet Nozzle Diameter",Lower=10e-6); Dinozzle_Shell as length (Brief="Shell Inlet Nozzle Diameter",Lower=10e-6); Aonozzle_Shell as area (Brief="Shell Outlet Nozzle Area",Lower=10e-6); Ainozzle_Shell as area (Brief="Shell Inlet Nozzle Area",Lower=10e-6); Aeonozzle_Shell as area (Brief="Shell Outlet Escape Area Under Nozzle",Lower=10e-6); Aeinozzle_Shell as area (Brief="Shell Inlet Escape Area Under Nozzle",Lower=10e-6); Hinozzle_Shell as length (Brief="Height Under Shell Inlet Nozzle",Lower=10e-6); Honozzle_Shell as length (Brief="Height Under Shell Outlet Nozzle",Lower=10e-6); Lcf as length (Brief="Bundle-to-Shell Clearance",Lower=10e-8); #+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++# # Tubes Geometrical Parameters #+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++# Ntt as Integer (Brief="Total Number of Tubes in Shell",Default=100,Lower=1); Pattern as Switcher (Brief="Tube Layout Characteristic Angle",Valid=["30","45","90"],Default="30"); Ltube as length (Brief="Effective Tube Length",Lower=0.1); pitch as length (Brief="Tube Pitch",Lower=1e-8); Kwall as conductivity (Brief="Tube Wall Material Thermal Conductivity"); Dotube as length (Brief="Tube Outside Diameter",Lower=10e-6); Ditube as length (Brief="Tube Inside Diameter",Lower=10e-6); Donozzle_Tube as length (Brief="Tube Outlet Nozzle Diameter",Lower=10e-6); Dinozzle_Tube as length (Brief="Tube Inlet Nozzle Diameter",Lower=10e-6); Aonozzle_Tube as area (Brief="Tube Outlet Nozzle Area",Lower=10e-6); Ainozzle_Tube as area (Brief="Tube Inlet Nozzle Area",Lower=10e-6); Kinlet_Tube as positive (Brief="Tube Inlet Nozzle Pressure Loss Coeff",Default=1.1); Koutlet_Tube as positive (Brief="Tube Outlet Nozzle Pressure Loss Coeff",Default=0.7); #+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++# # Baffles Geometrical Parameters #+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++# Bc as Integer (Brief="Baffle Cut",Default=25,Lower=25); Nb as Real (Brief="Number of Baffles",Lower=1); Lcd as length (Brief="Baffle-to-Shell Clearance",Lower=10e-8); Ltd as length (Brief="Tube-to-Bafflehole Clearance",Lower=10e-8); #+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++# # Fouling #+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++# Rfi as positive (Brief="Inside Fouling Resistance",Unit='m^2*K/kW',Default=1e-6,Lower=0); Rfo as positive (Brief="Outside Fouling Resistance",Unit='m^2*K/kW',Default=1e-6,Lower=0); #+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++# # Auxiliar Parameters - Must be hidden #+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++# Ods as Real (Brief="Baffle Cut Angle in Degrees"); Octl as Real (Brief="Baffle Cut Angle relative to the centerline in Degrees"); Ftw as Real (Brief="Fraction of Number of Tubes in Baffle Window"); Scd as area (Brief="Shell to Baffle Leakage Area"); Std as area (Brief="Tube to Baffle Hole Leakage Area"); Rs as Real (Brief="Ratio of the shell to baffle leakage area"); Dw as length (Brief="Hydraulic diameter of the baffle window"); SET M = PP.MolecularWeight(); Pi = 3.14159265; #"comments" Ods = (360/Pi)*acos(1-0.02*Bc); #"comments" Octl = (360/Pi)*acos((Dishell/(Dishell - Lcf - Dotube))*(1-0.02*Bc)); #"comments" Ftw = (Octl/360)-sin(Octl*Pi/180)/(2*Pi); #"comments" Scd = Pi*Dishell*Lcd*((360-Ods)/720); #"comments" Std = Pi*0.25*((Ltd + Dotube)^2-Dotube*Dotube)*Ntt*(1-Ftw); #"comments" Rs = Scd/(Scd+Std); #"comments" Dw = (4*abs((Pi*Dishell*Dishell*((Ods/360)-sin(Ods*Pi/180)/(2*Pi))/4)-(Ntt*Pi*Dotube*Dotube*Ftw/4)))/(Pi*Dotube*Ntt*Ftw+ Pi*Dishell*Ods/360); #"Tube Side Inlet Nozzle Area" Ainozzle_Tube = (Pi*Dinozzle_Tube*Dinozzle_Tube)/4; #"Tube Side Outlet Nozzle Area" Aonozzle_Tube = (Pi*Donozzle_Tube*Donozzle_Tube)/4; #"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 = (Pi*Donozzle_Shell*Donozzle_Shell)/4; #"Shell Inlet Nozzle Area" Ainozzle_Shell = (Pi*Dinozzle_Shell*Dinozzle_Shell)/4; #"Shell Outlet Escape Area Under Nozzle" Aeonozzle_Shell = Pi*Donozzle_Shell*Honozzle_Shell + 0.6*Aonozzle_Shell*(1-(Dotube/pitch)); #"Shell Inlet Escape Area Under Nozzle" Aeinozzle_Shell = Pi*Dinozzle_Shell*Hinozzle_Shell + 0.6*Ainozzle_Shell*(1-(Dotube/pitch)); 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*OutletTube.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*OutletTube.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 Inlet Heat Capacity" Tubes.Properties.Inlet.Cp = PP.LiquidCp(OutletTube.T,OutletTube.P,OutletTube.z); "Tube Stream Outlet Heat Capacity" Tubes.Properties.Outlet.Cp = PP.LiquidCp(OutletTube.T,OutletTube.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 inlet Viscosity" Tubes.Properties.Inlet.Mu = PP.LiquidViscosity(OutletTube.T,OutletTube.P,OutletTube.z); "Tube Stream Outlet Viscosity" Tubes.Properties.Outlet.Mu = PP.LiquidViscosity(OutletTube.T,OutletTube.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 Inlet Conductivity" Tubes.Properties.Inlet.K = PP.LiquidThermalConductivity(OutletTube.T,OutletTube.P,OutletTube.z); "Tube Stream Outlet Conductivity" Tubes.Properties.Outlet.K = PP.LiquidThermalConductivity(OutletTube.T,OutletTube.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 Inlet Heat Capacity" Tubes.Properties.Inlet.Cp = PP.VapourCp(OutletTube.T,OutletTube.P,OutletTube.z); "Tube Stream Outlet Heat Capacity" Tubes.Properties.Outlet.Cp = PP.VapourCp(OutletTube.T,OutletTube.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 Inlet Viscosity " Tubes.Properties.Inlet.Mu = PP.VapourViscosity(OutletTube.T,OutletTube.P,OutletTube.z); "Tube Stream Outlet Viscosity " Tubes.Properties.Outlet.Mu = PP.VapourViscosity(OutletTube.T,OutletTube.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 Inlet Conductivity " Tubes.Properties.Inlet.K = PP.VapourThermalConductivity(OutletTube.T,OutletTube.P,OutletTube.z); "Tube Stream Outlet Conductivity " Tubes.Properties.Outlet.K = PP.VapourThermalConductivity(OutletTube.T,OutletTube.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 Inlet Heat Capacity" Shell.Properties.Inlet.Cp = PP.LiquidCp(InletShell.T,InletShell.P,InletShell.z); "Shell Stream Outlet Heat Capacity" Shell.Properties.Outlet.Cp = PP.LiquidCp(OutletShell.T,OutletShell.P,OutletShell.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 Inlet Viscosity" Shell.Properties.Inlet.Mu = PP.LiquidViscosity(InletShell.T,InletShell.P,InletShell.z); "Shell Stream Outlet Viscosity" Shell.Properties.Outlet.Mu = PP.LiquidViscosity(OutletShell.T,OutletShell.P,OutletShell.z); "Shell Stream Average Conductivity" Shell.Properties.Average.K = PP.LiquidThermalConductivity(Shell.Properties.Average.T,Shell.Properties.Average.P,InletShell.z); "Shell Stream Inlet Conductivity" Shell.Properties.Inlet.K = PP.LiquidThermalConductivity(InletShell.T,InletShell.P,InletShell.z); "Shell Stream Outlet Conductivity" Shell.Properties.Outlet.K = PP.LiquidThermalConductivity(OutletShell.T,OutletShell.P,OutletShell.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 Inlet Heat Capacity" Shell.Properties.Inlet.Cp = PP.VapourCp(InletShell.T,InletShell.P,InletShell.z); "Shell Stream Outlet Heat Capacity" Shell.Properties.Outlet.Cp = PP.VapourCp(OutletShell.T,OutletShell.P,OutletShell.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 Inlet Viscosity" Shell.Properties.Inlet.Mu = PP.VapourViscosity(InletShell.T,InletShell.P,InletShell.z); "Shell Stream Outlet Viscosity" Shell.Properties.Outlet.Mu = PP.VapourViscosity(OutletShell.T,OutletShell.P,OutletShell.z); "Shell Stream Average Conductivity" Shell.Properties.Average.K = PP.VapourThermalConductivity(Shell.Properties.Average.T,Shell.Properties.Average.P,InletShell.z); "Shell Stream Inlet Conductivity" Shell.Properties.Inlet.K = PP.VapourThermalConductivity(InletShell.T,InletShell.P,InletShell.z); "Shell Stream Outlet Conductivity" Shell.Properties.Outlet.K = PP.VapourThermalConductivity(OutletShell.T,OutletShell.P,OutletShell.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" Shell.HeatTransfer.Jc = 0.55+0.72*(1-2*Ftw); "Jl Factor" Shell.HeatTransfer.Jl = 0.44*(1-Rs)+(1-0.44*(1-Rs))*exp(-2.2*(Scd + Std)/Shell.HeatTransfer.Sm); "Total J Factor" Shell.HeatTransfer.Jtotal = Shell.HeatTransfer.Jc*Shell.HeatTransfer.Jl*Shell.HeatTransfer.Jb*Shell.HeatTransfer.Jr*Shell.HeatTransfer.Js; "Mass Velocity in Window Zone" mw = Shell.Properties.Inlet.Fw/sqrt(abs(Shell.HeatTransfer.Sm*abs((Pi*Dishell*Dishell*((Ods/360)-sin(Ods*Pi/180)/(2*Pi))/4)-(Ntt*Pi*Dotube*Dotube*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.fi = 16/Tubes.HeatTransfer.Re; switch LaminarCorrelation case "Hausen": "Nusselt Number in Laminar Flow - Hausen Equation" Tubes.HeatTransfer.Nu = 3.665 + ((0.19*((Ditube/Ltube)*Tubes.HeatTransfer.Re*Tubes.HeatTransfer.PR)^0.8)/(1+0.117*((Ditube/Ltube)*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*(Ditube/Ltube))^(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.fi = 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.fi = 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 "30": "Shell Side Cross Flow Area" Shell.HeatTransfer.Sm= Baffles.Ls*(Lcf+((Dishell-Lcf-Dotube)/pitch)*(pitch-Dotube)); "Number of Tube rows Crossed in one Crossflow Section" Nc = Dishell*(1-0.02*Bc)/(0.866*pitch); "Number of Effective Crossflow rows in Each Window" Ncw = 0.8*(Dishell*0.01*Bc-(Lcf + Dotube)*0.5)/(0.866*pitch); "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 = Nss/(Dishell*(1-0.02*Bc)/(0.866*pitch)) ; "Ideal Shell Side Pressure Drop" Shell.PressureDrop.Pideal= 2*Shell.PressureDrop.fi*(Dishell*(1-0.02*Bc)/(0.866*pitch))*(Shell.Properties.Inlet.Fw/Shell.HeatTransfer.Sm)^2/(Shell.Properties.Average.rho*Shell.HeatTransfer.Phi); "Shell Pressure End Zones" Shell.PressureDrop.PdEndZones = Shell.PressureDrop.Pideal*(1+ (Ncw/(Dishell*(1-0.02*Bc)/(0.866*pitch))))*Rb*Rspd; switch ShellRange case "range1": "Ji Factor" Shell.HeatTransfer.Ji =1.40*((1.33*Dotube/pitch)^a)*Shell.HeatTransfer.Re^0.667; "Shell Side Pressure Drop Friction Factor" Shell.PressureDrop.fi=48*((1.33*Dotube/pitch)^b)*Shell.HeatTransfer.Re^-1; when Shell.HeatTransfer.Re > 10 switchto "range2"; case "range2": "Ji Factor" Shell.HeatTransfer.Ji =1.36*((1.33*Dotube/pitch)^a)*Shell.HeatTransfer.Re^-0.657; "Shell Side Pressure Drop Friction Factor" Shell.PressureDrop.fi=45.10*((1.33*Dotube/pitch)^b)*Shell.HeatTransfer.Re^-0.973; when Shell.HeatTransfer.Re > 100 switchto "range3"; case "range3": "Ji Factor" Shell.HeatTransfer.Ji =0.593*((1.33*Dotube/pitch)^a)*Shell.HeatTransfer.Re^-0.477; "Shell Side Pressure Drop Friction Factor" Shell.PressureDrop.fi=4.570*((1.33*Dotube/pitch)^b)*Shell.HeatTransfer.Re^-0.476; when Shell.HeatTransfer.Re > 1000 switchto "range4"; case "range4": "Ji Factor" Shell.HeatTransfer.Ji =0.321*((1.33*Dotube/pitch)^a)*Shell.HeatTransfer.Re^-0.388; "Shell Side Pressure Drop Friction Factor" Shell.PressureDrop.fi=0.486*((1.33*Dotube/pitch)^b)*Shell.HeatTransfer.Re^-0.152; when Shell.HeatTransfer.Re > 10000 switchto "range5"; case "range5": "Ji Factor" Shell.HeatTransfer.Ji =0.321*((1.33*Dotube/pitch)^a)*Shell.HeatTransfer.Re^-0.388; "Shell Side Pressure Drop Friction Factor" Shell.PressureDrop.fi=0.372*((1.33*Dotube/pitch)^b)*Shell.HeatTransfer.Re^-0.123; when Shell.HeatTransfer.Re < 10000 switchto "range4"; end case "45": "Shell Side Cross Flow Area" Shell.HeatTransfer.Sm= Baffles.Ls*(Lcf+((Dishell-Lcf-Dotube)/(0.707*pitch))*(pitch-Dotube)); "Number of Tube rows Crossed in one Crossflow Section" Nc = Dishell*(1-0.02*Bc)/(0.707*pitch); "Number of Effective Crossflow rows in Each Window" Ncw = 0.8*(Dishell*0.01*Bc-(Lcf + Dotube)*0.5)/(0.707*pitch); "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 = Nss/(Dishell*(1-0.02*Bc)/(0.707*pitch)) ; "Ideal Shell Side Pressure Drop" Shell.PressureDrop.Pideal= 2*Shell.PressureDrop.fi*(Dishell*(1-0.02*Bc)/(0.707*pitch))*(Shell.Properties.Inlet.Fw/Shell.HeatTransfer.Sm)^2/(Shell.Properties.Average.rho*Shell.HeatTransfer.Phi); "Shell Pressure End Zones" Shell.PressureDrop.PdEndZones = Shell.PressureDrop.Pideal*(1+ (Ncw/(Dishell*(1-0.02*Bc)/(0.707*pitch))))*Rb*Rspd; switch ShellRange case "range1": "Ji Factor" Shell.HeatTransfer.Ji =1.550*((1.33*Dotube/pitch)^a)*Shell.HeatTransfer.Re^0.667; "Shell Side Pressure Drop Friction Factor" Shell.PressureDrop.fi=32*((1.33*Dotube/pitch)^b)*Shell.HeatTransfer.Re^-1; when Shell.HeatTransfer.Re > 10 switchto "range2"; case "range2": "Ji Factor" Shell.HeatTransfer.Ji =0.498*((1.33*Dotube/pitch)^a)*Shell.HeatTransfer.Re^0.656; "Shell Side Pressure Drop Friction Factor" Shell.PressureDrop.fi=26.20*((1.33*Dotube/pitch)^b)*Shell.HeatTransfer.Re^-0.913; when Shell.HeatTransfer.Re > 100 switchto "range3"; case "range3": "Ji Factor" Shell.HeatTransfer.Ji =0.730*((1.33*Dotube/pitch)^a)*Shell.HeatTransfer.Re^0.500; "Shell Side Pressure Drop Friction Factor" Shell.PressureDrop.fi=3.50*((1.33*Dotube/pitch)^b)*Shell.HeatTransfer.Re^-0.476; when Shell.HeatTransfer.Re > 1000 switchto "range4"; case "range4": "Ji Factor" Shell.HeatTransfer.Ji =0.370*((1.33*Dotube/pitch)^a)*Shell.HeatTransfer.Re^-0.396; "Shell Side Pressure Drop Friction Factor" Shell.PressureDrop.fi=0.333*((1.33*Dotube/pitch)^b)*Shell.HeatTransfer.Re^-0.136; when Shell.HeatTransfer.Re > 10000 switchto "range5"; case "range5": "Ji Factor" Shell.HeatTransfer.Ji =0.370*((1.33*Dotube/pitch)^a)*Shell.HeatTransfer.Re^-0.396; "Shell Side Pressure Drop Friction Factor" Shell.PressureDrop.fi=0.303*((1.33*Dotube/pitch)^b)*Shell.HeatTransfer.Re^-0.126; when Shell.HeatTransfer.Re < 10000 switchto "range4"; end case "90": "Shell Side Cross Flow Area" Shell.HeatTransfer.Sm= Baffles.Ls*(Lcf+((Dishell-Lcf-Dotube)/pitch)*(pitch-Dotube)); "Number of Tube rows Crossed in one Crossflow Section" Nc = Dishell*(1-0.02*Bc)/pitch; "Number of Effective Crossflow rows in Each Window" Ncw = 0.8*(Dishell*0.01*Bc-(Lcf + Dotube)*0.5)/pitch; "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 = Nss/(Dishell*(1-0.02*Bc)/pitch) ; "Ideal Shell Side Pressure Drop" Shell.PressureDrop.Pideal= 2*Shell.PressureDrop.fi*(Dishell*(1-0.02*Bc)/pitch)*(Shell.Properties.Inlet.Fw/Shell.HeatTransfer.Sm)^2/(Shell.Properties.Average.rho*Shell.HeatTransfer.Phi); "Shell Pressure End Zones" Shell.PressureDrop.PdEndZones = Shell.PressureDrop.Pideal*(1+ (Ncw/(Dishell*(1-0.02*Bc)/pitch)))*Rb*Rspd; switch ShellRange case "range1": "Ji Factor" Shell.HeatTransfer.Ji =0.970*((1.33*Dotube/pitch)^a)*Shell.HeatTransfer.Re^-0.667; "Shell Side Pressure Drop Friction Factor" Shell.PressureDrop.fi=35*((1.33*Dotube/pitch)^b)*Shell.HeatTransfer.Re^-1; when Shell.HeatTransfer.Re > 10 switchto "range2"; case "range2": "Ji Factor" Shell.HeatTransfer.Ji =0.900*((1.33*Dotube/pitch)^a)*Shell.HeatTransfer.Re^-0.631; "Shell Side Pressure Drop Friction Factor" Shell.PressureDrop.fi=32.10*((1.33*Dotube/pitch)^b)*Shell.HeatTransfer.Re^-0.963; when Shell.HeatTransfer.Re > 100 switchto "range3"; case "range3": "Ji Factor" Shell.HeatTransfer.Ji =0.408*((1.33*Dotube/pitch)^a)*Shell.HeatTransfer.Re^-0.460; "Shell Side Pressure Drop Friction Factor" Shell.PressureDrop.fi=6.090*((1.33*Dotube/pitch)^b)*Shell.HeatTransfer.Re^-0.602; when Shell.HeatTransfer.Re > 1000 switchto "range4"; case "range4": "Ji Factor" Shell.HeatTransfer.Ji =0.107*((1.33*Dotube/pitch)^a)*Shell.HeatTransfer.Re^-0.266; "Shell Side Pressure Drop Friction Factor" Shell.PressureDrop.fi=0.0815*((1.33*Dotube/pitch)^b)*Shell.HeatTransfer.Re^0.022; when Shell.HeatTransfer.Re > 10000 switchto "range5"; case "range5": "Ji Factor" Shell.HeatTransfer.Ji =0.370*((1.33*Dotube/pitch)^a)*Shell.HeatTransfer.Re^-0.395; "Shell Side Pressure Drop Friction Factor" Shell.PressureDrop.fi=0.391*((1.33*Dotube/pitch)^b)*Shell.HeatTransfer.Re^-0.148; when Shell.HeatTransfer.Re < 10000 switchto "range4"; end end switch ShellFlowRegime case "deep laminar": "Jr Factor" Shell.HeatTransfer.Jr = (10/((Nc +Ncw)*(Nb+1)))^0.18; "Js Factor" Shell.HeatTransfer.Js = (Nb-1+(Baffles.Lsi/Baffles.Ls)^0.7 + (Baffles.Lso/Baffles.Ls)^0.7)/(Nb-1+(Baffles.Lsi/Baffles.Ls) + (Baffles.Lso/Baffles.Ls)); "Jb Factor" Shell.HeatTransfer.Jb = exp(-1.35*( Lcf+ Dotube)*Baffles.Ls/Shell.HeatTransfer.Sm*(1-(2*(Nss/Nc)^(1/3)))); "ByPass Correction Factor for Pressure Drop" Rb = exp(-4.7*((Lcf + Dotube)*Baffles.Ls/Shell.HeatTransfer.Sm)*(1-(2*Rss)^(1/3))); "Pressure Drop Correction Factor for Unequal Baffle Spacing" Rspd = (Baffles.Ls/Baffles.Lso) + (Baffles.Ls/Baffles.Lsi); "Shell Pressure Drop Baffle Window" Shell.PressureDrop.Pdwindow = Nb*((26/Shell.Properties.Average.rho)*mw*Shell.Properties.Average.Mu*(Ncw/(pitch-Dotube)+ Baffles.Ls/(Dw*Dw))+ 0.5*mw*mw/Shell.Properties.Average.rho)*exp(-1.33*(1+Rs)*((Scd + Std)/Shell.HeatTransfer.Sm)^(-0.15*(1+Rs) + 0.8)); when Shell.HeatTransfer.Re > 20 switchto "laminar"; case "laminar": "Jr Factor" Shell.HeatTransfer.Jr = (10/((Nc +Ncw)*(Nb+1)))^0.18 + (0.25-0.0125*Shell.HeatTransfer.Re)*((10/((Nc +Ncw)*(Nb+1)))^0.18 - 1); "Js Factor" Shell.HeatTransfer.Js = (Nb-1+(Baffles.Lsi/Baffles.Ls)^0.7 + (Baffles.Lso/Baffles.Ls)^0.7)/(Nb-1+(Baffles.Lsi/Baffles.Ls) + (Baffles.Lso/Baffles.Ls)); "Jb Factor" Shell.HeatTransfer.Jb = exp(-1.35*( Lcf+ Dotube)*Baffles.Ls/Shell.HeatTransfer.Sm*(1-(2*(Nss/Nc)^(1/3)))); "ByPass Correction Factor for Pressure Drop" Rb = exp(-4.7*((Lcf + Dotube)*Baffles.Ls/Shell.HeatTransfer.Sm)*(1-(2*Rss)^(1/3))); "Pressure Drop Correction Factor for Unequal Baffle Spacing" Rspd = (Baffles.Ls/Baffles.Lso) + (Baffles.Ls/Baffles.Lsi); "Shell Pressure Drop Baffle Window" Shell.PressureDrop.Pdwindow = Nb*((26/Shell.Properties.Average.rho)*mw*Shell.Properties.Average.Mu*(Ncw/(pitch-Dotube)+ Baffles.Ls/(Dw*Dw))+ 0.5*mw*mw/Shell.Properties.Average.rho)*exp(-1.33*(1+Rs)*((Scd + Std)/Shell.HeatTransfer.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" Shell.HeatTransfer.Jr = 1; "Js Factor" Shell.HeatTransfer.Js = (Nb-1+(Baffles.Lsi/Baffles.Ls)^0.4 + (Baffles.Lso/Baffles.Ls)^0.4)/(Nb-1+(Baffles.Lsi/Baffles.Ls) + (Baffles.Lso/Baffles.Ls)); "Jb Factor" Shell.HeatTransfer.Jb = exp(-1.25*( Lcf+ Dotube)*Baffles.Ls/Shell.HeatTransfer.Sm*(1-(2*(Nss/Nc)^(1/3)))); "ByPass Correction Factor for Pressure Drop" Rb = exp(-3.7*((Lcf + Dotube)*Baffles.Ls/Shell.HeatTransfer.Sm)*(1-(2*Rss)^(1/3))); "Pressure Drop Correction Factor for Unequal Baffle Spacing" Rspd = (Baffles.Ls/Baffles.Lso)^1.8 + (Baffles.Ls/Baffles.Lsi)^1.8; "Shell Pressure Drop Baffle Window" Shell.PressureDrop.Pdwindow = Nb*((2+0.6*Ncw)*0.5*mw*mw/Shell.Properties.Average.rho)*exp(-1.33*(1+Rs)*((Scd + Std)/Shell.HeatTransfer.Sm)^(-0.15*(1+Rs) + 0.8)); when Shell.HeatTransfer.Re < 100 switchto "laminar"; end "Shell Pressure Drop Cross Flow" Shell.PressureDrop.PdCross = Shell.PressureDrop.Pideal*Rb*(Nb-1)*exp(-1.33*(1+Rs)*((Scd + Std)/Shell.HeatTransfer.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.PdTube = 2*Tubes.PressureDrop.fi*Ltube*Tubes.Properties.Average.rho*(Tubes.HeatTransfer.Vtube^2)*Tpass/(Ditube*Tubes.HeatTransfer.Phi); "Pressure Drop Tube Side Inlet Nozzle" Tubes.PressureDrop.Pdnozzle_in = 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.Pdnozzle_out = 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.Pdnozzle_in = (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.Pdnozzle_out = (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.Pdtotal; "Pressure Drop Tube Stream" OutletTube.P = InletTube.P - Tubes.PressureDrop.Pdtotal; "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*Tpass/((Pi*Ditube*Ditube/4)*Tubes.Properties.Average.rho*Ntt); "Tube Side Reynolds Number" Tubes.HeatTransfer.Re = (Tubes.Properties.Average.rho*Tubes.HeatTransfer.Vtube*Ditube)/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/Ditube)*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/(Dotube/(Tubes.HeatTransfer.htube*Ditube)+Rfo+Rfi*(Dotube/Ditube)+(Dotube*ln(Dotube/Ditube)/(2*Kwall))+(1/(Shell.HeatTransfer.hshell))); "Overall Heat Transfer Coefficient Clean" Details.Uc=1/(Dotube/(Tubes.HeatTransfer.htube*Ditube)+(Dotube*ln(Dotube/Ditube)/(2*Kwall))+(1/(Shell.HeatTransfer.hshell))); "Exchange Surface Area" Details.A=Pi*Dotube*Ntt*Ltube; "Baffles Spacing" Ltube = Baffles.Lsi+Baffles.Lso+Baffles.Ls*(Nb-1); "Shell Side Reynolds Number" Shell.HeatTransfer.Re = (Dotube*Shell.Properties.Inlet.Fw/Shell.HeatTransfer.Sm)/Shell.Properties.Average.Mu; "Shell Heat Transfer Coefficient" Shell.HeatTransfer.hshell = Shell.HeatTransfer.Ji*(Shell.Properties.Average.Cp/Shell.Properties.Average.Mw)*(Shell.Properties.Inlet.Fw/Shell.HeatTransfer.Sm)*(Shell.HeatTransfer.PR^(-2/3))*Shell.HeatTransfer.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*Dotube*Ntt*Ltube; "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*Dotube*Ntt*Ltube*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