Ignore:
Timestamp:
Jan 9, 2007, 12:15:56 PM (15 years ago)
Author:
gerson bicca
Message:

updated

File:
1 edited

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Removed
  • mso/eml/heat_exchangers/DoublePipe.mso

    r78 r100  
    1919
    2020using "HEX_Engine";
    21 #=====================================================================
     21#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++#
    2222#       Basic Models for Double Pipe Heat Exchangers
    23 #=====================================================================
     23#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++#
    2424
    2525Model DoublePipe_Basic
     
    7070        Properties.Cold.Average.Mw = sum(M*Inlet.Cold.z);
    7171
    72 
    73 
    7472if Inlet.Cold.v equal 0
    7573        then   
     
    208206end
    209207
    210 #=====================================================================
     208#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++#
    211209#       Thermal Details
    212 #=====================================================================
     210#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++#
    213211"Hot Stream Heat Capacity"
    214212        Details.Ch =Inlet.Hot.F*Properties.Hot.Average.Cp;
     
    225223"Heat Capacity Ratio"   
    226224        Details.Cr*Details.Cmax   = Details.Cmin;
    227 #=====================================================================
     225#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++#
    228226#       Energy Balance
    229 #=====================================================================
     227#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++#
    230228"Energy Balance Hot Stream"
    231229        Details.Q = Inlet.Hot.F*(Inlet.Hot.h-Outlet.Hot.h);
     
    234232        Details.Q = Inlet.Cold.F*(Outlet.Cold.h - Inlet.Cold.h);
    235233
    236 #=====================================================================
     234#--------------------------------------------------------------------
    237235#       Material Balance
    238 #=====================================================================
     236#--------------------------------------------------------------------
    239237"Flow Mass Inlet Cold Stream"
    240238        Properties.Cold.Inlet.Fw        =  sum(M*Inlet.Cold.z)*Inlet.Cold.F;
     
    255253        Inlet.Cold.F = Outlet.Cold.F;
    256254
    257 #======================================
     255#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++#
    258256#       Constraints
    259 #======================================
     257#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++#
    260258"Hot Stream Molar Fraction Constraint"
    261259        Outlet.Hot.z=Inlet.Hot.z;
     
    294292
    295293end
    296 
    297 "Overall Heat Transfer Coefficient"
    298 #       Details.U*(Resistances.Rtube+Resistances.Rwall+Resistances.Rshell)=1;
    299         Details.U=1/(Resistances.Rtube+Resistances.Rwall+Resistances.Rshell);
    300294
    301295end
     
    355349"Outer Pipe Film Coefficient"
    356350        Outer.HeatTransfer.hcoeff= HE.PipeFilmCoeff(Outer.HeatTransfer.Re,Outer.HeatTransfer.PR,Properties.Hot.Average.K,Outer.HeatTransfer.Dh,Lpipe)*Outer.HeatTransfer.Phi;
    357 #       Outer.HeatTransfer.hcoeff= (0.027*Outer.HeatTransfer.Re^(4/5)*Outer.HeatTransfer.PR^(1/3)*Properties.Hot.Average.K/Outer.HeatTransfer.Dh)*Outer.HeatTransfer.Phi;
    358351
    359352"Inner Pipe Film Coefficient"
    360353        Inner.HeatTransfer.hcoeff= HE.PipeFilmCoeff(Inner.HeatTransfer.Re,Inner.HeatTransfer.PR,Properties.Cold.Average.K,DiInner,Lpipe)*Inner.HeatTransfer.Phi;
    361 #       Inner.HeatTransfer.hcoeff= (0.027*Inner.HeatTransfer.Re^(4/5)*Inner.HeatTransfer.PR^(1/3)*Properties.Cold.Average.K/DiInner)*Inner.HeatTransfer.Phi;
    362354
    363355"Outer Pipe Pressure Drop"
     
    407399"Inner Pipe Film Coefficient"
    408400        Inner.HeatTransfer.hcoeff= HE.PipeFilmCoeff(Inner.HeatTransfer.Re,Inner.HeatTransfer.PR,Properties.Hot.Average.K,DiInner,Lpipe)*Inner.HeatTransfer.Phi;
    409 #       Inner.HeatTransfer.hcoeff= (0.027*Inner.HeatTransfer.Re^(4/5)*Inner.HeatTransfer.PR^(1/3)*Properties.Hot.Average.K/DiInner)*Inner.HeatTransfer.Phi;
    410401
    411402"Outer Pipe Film Coefficient"
    412403        Outer.HeatTransfer.hcoeff= HE.PipeFilmCoeff(Outer.HeatTransfer.Re,Outer.HeatTransfer.PR,Properties.Cold.Average.K,Outer.HeatTransfer.Dh,Lpipe)*Outer.HeatTransfer.Phi;
    413 #       Outer.HeatTransfer.hcoeff= (0.027*Outer.HeatTransfer.Re^(4/5)*Outer.HeatTransfer.PR^(1/3)*Properties.Cold.Average.K/Outer.HeatTransfer.Dh)*Outer.HeatTransfer.Phi;
    414404
    415405"Outer Pipe Pressure Drop"
     
    446436        Outer.HeatTransfer.Vmean*(Outer.HeatTransfer.As*Properties.Cold.Average.rho)= Properties.Cold.Inlet.Fw;
    447437       
    448        
    449438"Inner Pipe Velocity"
    450439        Inner.HeatTransfer.Vmean*(Inner.HeatTransfer.As*Properties.Hot.Average.rho)     = Properties.Hot.Inlet.Fw;
     
    461450        Resistances.Rshell*(Outer.HeatTransfer.hcoeff)=1;
    462451
    463 
     452"Overall Heat Transfer Coefficient Clean"
     453        Details.Uc*(Resistances.Rtube+Resistances.Rwall+Resistances.Rshell)=1;
     454
     455"Overall Heat Transfer Coefficient Dirty"
     456        Details.Ud*(Resistances.Rfi*(DoInner/DiInner) + Resistances.Rfo + Resistances.Rtube + Resistances.Rwall + Resistances.Rshell)=1;
     457       
    464458end
    465459
    466460Model DoublePipe_Basic_NTU                      as DoublePipe
    467 #=====================================================================
     461#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++#
    468462#       Basic Model Double Pipe Heat Exchanger - NTU Method
    469 #=====================================================================
     463#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++#
    470464VARIABLES
    471465
     
    481475
    482476Model DoublePipe_Basic_LMTD                     as DoublePipe
    483 #=====================================================================
     477#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++#
    484478#       Basic Model for Double Pipe Heat Exchanger- LMTD Method
    485 #=====================================================================
     479#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++#
    486480VARIABLES
    487481
     
    518512
    519513"Exchange Surface Area"
    520         Details.Q = Details.U*Pi*DoInner*Lpipe*LMTD;
     514        Details.Q = Details.Ud*Pi*DoInner*Lpipe*LMTD;
    521515
    522516end
     
    552546       
    553547        then   
    554 "Effectiveness in Cocurrent Flow"
     548"Effectiveness"
    555549        Eft = 1-exp(-Details.NTU);
    556550       
     
    599593        Kwall           as conductivity (Brief="Tube Wall Material Thermal Conductivity",Default=1.0);
    600594
     595VARIABLES
     596
     597Unity(Npipe)  as DoublePipe_Basic;
     598
    601599SET
    602600        Pi      = 3.14159265;
    603601        Hside   = HE.FluidAlocation();
    604 
    605 VARIABLES
    606 
    607 Unity(Npipe)  as DoublePipe_Basic;
     602       
     603#"Inner Pipe Cross Sectional Area for Flow"
     604        Unity.Inner.HeatTransfer.As=Pi*DiInner*DiInner/4;
     605       
     606#"Outer Pipe Cross Sectional Area for Flow"
     607        Unity.Outer.HeatTransfer.As=Pi*(DiOuter*DiOuter-DoInner*DoInner)/4;
     608       
     609#"Inner Pipe Hydraulic Diameter for Heat Transfer"
     610        Unity.Inner.HeatTransfer.Dh=DiInner;
     611       
     612#"Outer Pipe Hydraulic Diameter for Heat Transfer"
     613        Unity.Outer.HeatTransfer.Dh=(DiOuter*DiOuter-DoInner*DoInner)/DoInner;
     614
     615#"Inner Pipe Hydraulic Diameter for Pressure Drop"
     616        Unity.Inner.PressureDrop.Dh=DiInner;
     617       
     618#"Outer Pipe Hydraulic Diameter for Pressure Drop"
     619        Unity.Outer.PressureDrop.Dh=DiOuter-DoInner;
    608620
    609621EQUATIONS
    610622
    611623for i in [1:Npipe]
     624
     625"Overall Heat Transfer Coefficient Clean"
     626        Unity(i).Details.Uc*(Unity(i).Resistances.Rtube+Unity(i).Resistances.Rwall+Unity(i).Resistances.Rshell)=1;
     627
     628"Overall Heat Transfer Coefficient Dirty"
     629        Unity(i).Details.Ud*(Unity(i).Resistances.Rfi*(DoInner/DiInner) + Unity(i).Resistances.Rfo + Unity(i).Resistances.Rtube + Unity(i).Resistances.Rwall + Unity(i).Resistances.Rshell)=1;
    612630
    613631"Exchange Surface Area"
    614632        Unity(i).Details.A=Pi*DoInner*Lpipe;
    615633       
    616 "Inner Pipe Cross Sectional Area for Flow"
    617         Unity(i).Inner.HeatTransfer.As=Pi*DiInner*DiInner/4;
    618        
    619 "Outer Pipe Cross Sectional Area for Flow"
    620         Unity(i).Outer.HeatTransfer.As=Pi*(DiOuter*DiOuter-DoInner*DoInner)/4;
    621        
    622 "Inner Pipe Hydraulic Diameter for Heat Transfer"
    623         Unity(i).Inner.HeatTransfer.Dh=DiInner;
    624        
    625 "Outer Pipe Hydraulic Diameter for Heat Transfer"
    626         Unity(i).Outer.HeatTransfer.Dh=(DiOuter*DiOuter-DoInner*DoInner)/DoInner;
    627 
    628 "Inner Pipe Hydraulic Diameter for Pressure Drop"
    629         Unity(i).Inner.PressureDrop.Dh=DiInner;
    630        
    631 "Outer Pipe Hydraulic Diameter for Pressure Drop"
    632         Unity(i).Outer.PressureDrop.Dh=DiOuter-DoInner;
    633 
    634634if Hside equal 1
    635635       
     
    693693
    694694"Outer Pipe Phi correction"
    695         Unity(i).Outer.HeatTransfer.Phi                 = HE.PhiCorrection(Unity(i).Properties.Cold.Average.Mu,Unity(i).Properties.Cold.Wall.Mu);
     695        Unity(i).Outer.HeatTransfer.Phi         = HE.PhiCorrection(Unity(i).Properties.Cold.Average.Mu,Unity(i).Properties.Cold.Wall.Mu);
    696696       
    697697"Inner Pipe Phi correction"
     
    739739
    740740Model Multitubular_Basic_LMTD           as Multitubular_Basic
    741 #=====================================================================
     741#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++#
    742742#       Basic Model for Double Pipe Heat Exchanger- LMTD Method
    743 #=====================================================================
     743#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++#
    744744VARIABLES
    745745
     
    777777
    778778"Exchange Surface Area"
    779         Unity(i).Details.Q = Unity(i).Details.U*Unity(i).Details.A*LMTD(i);
     779        Unity(i).Details.Q = Unity(i).Details.Ud*Unity(i).Details.A*LMTD(i);
    780780
    781781end
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