Changeset 136


Ignore:
Timestamp:
Jan 25, 2007, 6:59:01 PM (16 years ago)
Author:
gerson bicca
Message:

solved convergence problem for multitubular heat exchanger

Location:
trunk
Files:
1 added
2 edited

Legend:

Unmodified
Added
Removed
  • trunk/eml/heat_exchangers/DoublePipe.mso

    r129 r136  
    628628
    629629"Overall Heat Transfer Coefficient Clean"
    630         Unity(i).Details.Uc*(Unity(i).Resistances.Rtube+Unity(i).Resistances.Rwall+Unity(i).Resistances.Rshell)=1;
     630        (1/Unity(i).Details.Ud)=(1/Unity(i).Details.Uc)+Unity(i).Resistances.Rfo+Unity(i).Resistances.Rfi*(DoInner/DiInner);
     631
    631632
    632633"Overall Heat Transfer Coefficient Dirty"
    633         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;
     634        Unity(i).Details.Ud=1/(DoInner/(Unity(i).Inner.HeatTransfer.hcoeff*DiInner)+Unity(i).Resistances.Rfo+Unity(i).Resistances.Rfi*(DoInner/DiInner)+(DoInner*ln(DoInner/DiInner)/(2*Kwall))+(1/(Unity(i).Outer.HeatTransfer.hcoeff)));
    634635
    635636"Exchange Surface Area"
     
    793794
    794795"Exchange Surface Area"
    795         Unity(i).Details.Q = Unity(i).Details.Ud*Unity(i).Details.A*LMTD(i);
     796        Unity(i).Details.Q = Unity(i).Details.Ud*Pi*DoInner*Lpipe*LMTD(i);
    796797
    797798end
  • trunk/sample/heat_exchangers/Sample_Multitubular.mso

    r110 r136  
    11#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
    22# Series of Double Pipe Heat Exchanger
     3#
     4# for fast convergence use the results created for the first FlowSheet
     5# called "Double_Pipe_Multitubular_LMTD" and use it as guess for the second one
     6# called "Double_Pipe_Multitubular_NTU".
     7#
    38#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
    49using "heat_exchangers/DoublePipe.mso";
    510
    6 FlowSheet Double_Pipe_Multitubular
     11FlowSheet Double_Pipe_Multitubular_LMTD
    712       
    813DEVICES
    914        Pipe            as Multitubular_Cocurrent_LMTD;
    10         streamhot       as streamTP;
    11         streamcold      as streamTP;
     15        streamhot       as stream_therm;
     16        streamcold      as stream_therm;
    1217
    1318PARAMETERS
     
    4247Pipe.DiOuter            =       0.07793*"m";
    4348Pipe.Kwall              =       0.057 *"kW/m/K";
    44 Pipe.Lpipe                      =       3*"m";
     49Pipe.Lpipe                      =       1.7*"m";
    4550
    4651SPECIFY
     
    4954#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
    5055
    51         streamhot.F = 100               * "kmol/h";
    52         streamhot.T = (70+273.15)   * "K";
    53         streamhot.P = 5                         * "bar";
     56        streamhot.F = 10        * "kmol/h";
     57        streamhot.T = 315   * "K";
     58        streamhot.P = 5         * "bar";
    5459        streamhot.z = [1,0];
     60        streamhot.v = 0;
    5561       
    5662#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
     
    5864#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
    5965
    60         streamcold.F = 5                        * "kmol/h";
    61         streamcold.P = 5                * "bar";
    62         streamcold.T = (25+273.15)      * "K";
     66        streamcold.F = 5                * "kmol/h";
     67        streamcold.P = 5        * "bar";
     68        streamcold.T = 293              * "K";
    6369    streamcold.z = [0,1];
     70    streamcold.v = 0;
    6471       
    6572#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
     
    7683end
    7784
     85FlowSheet Double_Pipe_Multitubular_NTU
     86       
     87DEVICES
     88        Pipe            as Multitubular_Cocurrent_NTU;
     89        streamhot       as stream_therm;
     90        streamcold      as stream_therm;
     91
     92PARAMETERS
     93
     94        PP                      as CalcObject (File="vrpp");
     95        NComp           as Integer;
     96       
     97CONNECTIONS
     98
     99        streamhot                       to Pipe.Unity(1).Inlet.Hot;
     100        streamcold                      to Pipe.Unity(1).Inlet.Cold;
     101SET
     102
     103PP.LiquidModel          = "PR";
     104PP.VapourModel          = "PR";
     105PP.Components           = ["methanol","water"];
     106NComp                           = PP.NumberOfComponents;
     107Pipe.Npipe = 2;
     108
     109#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
     110#   Options
     111#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
     112
     113Pipe.HE.TurbulentFlow  = "SiederTate";
     114       
     115#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
     116# Double Pipe Geometrical Parameters and Alocation
     117#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
     118Pipe.HE.HotSide         =       "Inner";
     119Pipe.DoInner            =       0.04826*"m";
     120Pipe.DiInner            =       0.04089*"m";
     121Pipe.DiOuter            =       0.07793*"m";
     122Pipe.Kwall              =       0.057 *"kW/m/K";
     123Pipe.Lpipe                      =       1.7*"m";
     124
     125SPECIFY
     126#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
     127#               Hot Stream
     128#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
     129
     130        streamhot.F = 10        * "kmol/h";
     131        streamhot.T = 315   * "K";
     132        streamhot.P = 5         * "bar";
     133        streamhot.z = [1,0];
     134        streamhot.v = 0;
     135       
     136#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
     137#    Cold Stream
     138#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
     139
     140        streamcold.F = 5                * "kmol/h";
     141        streamcold.P = 5        * "bar";
     142        streamcold.T = 293              * "K";
     143    streamcold.z = [0,1];
     144    streamcold.v = 0;
     145       
     146#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
     147#       Fouling
     148#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
     149
     150Pipe.Unity.Resistances.Rfi = 0*"m^2*K/kW";
     151Pipe.Unity.Resistances.Rfo = 0*"m^2*K/kW";
     152
     153OPTIONS
     154
     155mode      = "steady";
     156guessFile = "Double_Pipe_Multitubular";
     157
     158end
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