# Changeset 136

Ignore:
Timestamp:
Jan 25, 2007, 6:59:01 PM (15 years ago)
Message:

solved convergence problem for multitubular heat exchanger

Location:
trunk
Files:
1 added
2 edited

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

 r129 "Overall Heat Transfer Coefficient Clean" Unity(i).Details.Uc*(Unity(i).Resistances.Rtube+Unity(i).Resistances.Rwall+Unity(i).Resistances.Rshell)=1; (1/Unity(i).Details.Ud)=(1/Unity(i).Details.Uc)+Unity(i).Resistances.Rfo+Unity(i).Resistances.Rfi*(DoInner/DiInner); "Overall Heat Transfer Coefficient Dirty" 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; 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))); "Exchange Surface Area" "Exchange Surface Area" Unity(i).Details.Q = Unity(i).Details.Ud*Unity(i).Details.A*LMTD(i); Unity(i).Details.Q = Unity(i).Details.Ud*Pi*DoInner*Lpipe*LMTD(i); end
• ## trunk/sample/heat_exchangers/Sample_Multitubular.mso

 r110 #++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ # Series of Double Pipe Heat Exchanger # # for fast convergence use the results created for the first FlowSheet # called "Double_Pipe_Multitubular_LMTD" and use it as guess for the second one # called "Double_Pipe_Multitubular_NTU". # #++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ using "heat_exchangers/DoublePipe.mso"; FlowSheet Double_Pipe_Multitubular FlowSheet Double_Pipe_Multitubular_LMTD DEVICES Pipe            as Multitubular_Cocurrent_LMTD; streamhot       as streamTP; streamcold      as streamTP; streamhot       as stream_therm; streamcold      as stream_therm; PARAMETERS Pipe.DiOuter            =       0.07793*"m"; Pipe.Kwall              =       0.057 *"kW/m/K"; Pipe.Lpipe                      =       3*"m"; Pipe.Lpipe                      =       1.7*"m"; SPECIFY #++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ streamhot.F = 100               * "kmol/h"; streamhot.T = (70+273.15)   * "K"; streamhot.P = 5                         * "bar"; streamhot.F = 10        * "kmol/h"; streamhot.T = 315   * "K"; streamhot.P = 5         * "bar"; streamhot.z = [1,0]; streamhot.v = 0; #++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ #++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ streamcold.F = 5                        * "kmol/h"; streamcold.P = 5                * "bar"; streamcold.T = (25+273.15)      * "K"; streamcold.F = 5                * "kmol/h"; streamcold.P = 5        * "bar"; streamcold.T = 293              * "K"; streamcold.z = [0,1]; streamcold.v = 0; #++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ end FlowSheet Double_Pipe_Multitubular_NTU DEVICES Pipe            as Multitubular_Cocurrent_NTU; streamhot       as stream_therm; streamcold      as stream_therm; PARAMETERS PP                      as CalcObject (File="vrpp"); NComp           as Integer; CONNECTIONS streamhot                       to Pipe.Unity(1).Inlet.Hot; streamcold                      to Pipe.Unity(1).Inlet.Cold; SET PP.LiquidModel          = "PR"; PP.VapourModel          = "PR"; PP.Components           = ["methanol","water"]; NComp                           = PP.NumberOfComponents; Pipe.Npipe = 2; #++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ #   Options #++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Pipe.HE.TurbulentFlow  = "SiederTate"; #++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ # Double Pipe Geometrical Parameters and Alocation #++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Pipe.HE.HotSide         =       "Inner"; Pipe.DoInner            =       0.04826*"m"; Pipe.DiInner            =       0.04089*"m"; Pipe.DiOuter            =       0.07793*"m"; Pipe.Kwall              =       0.057 *"kW/m/K"; Pipe.Lpipe                      =       1.7*"m"; SPECIFY #++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ #               Hot Stream #++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ streamhot.F = 10        * "kmol/h"; streamhot.T = 315   * "K"; streamhot.P = 5         * "bar"; streamhot.z = [1,0]; streamhot.v = 0; #++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ #    Cold Stream #++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ streamcold.F = 5                * "kmol/h"; streamcold.P = 5        * "bar"; streamcold.T = 293              * "K"; streamcold.z = [0,1]; streamcold.v = 0; #++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ #       Fouling #++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Pipe.Unity.Resistances.Rfi = 0*"m^2*K/kW"; Pipe.Unity.Resistances.Rfo = 0*"m^2*K/kW"; OPTIONS mode      = "steady"; guessFile = "Double_Pipe_Multitubular"; end
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