Ignore:
Timestamp:
Jun 12, 2017, 10:29:43 AM (6 years ago)
Author:
Argimiro Resende Secchi
Message:

Fixed convergence problem in detailed heat exchanger.

Location:
trunk/eml/heat_exchangers
Files:
2 edited

Legend:

Unmodified
Added
Removed

  • trunk/eml/heat_exchangers/HEX_Engine.mso

    r995 r1005  
    107107       
    108108VARIABLES
    109 TubeFriction    as press_delta  (Brief="Tube Pressure Drop due to friction", Symbol = "\Delta P_{tube}", Default=0.01, Lower=1E-10,DisplayUnit='kPa');
     109TubeFriction    as press_delta  (Brief="Tube Pressure Drop due to friction", Symbol = "\Delta P_{tube}", Default=0.01, Lower=0,DisplayUnit='kPa');
    110110InletNozzle     as press_delta  (Brief="Inlet Nozzle Pressure Drop", Symbol = "\Delta P_{Nozzle\_In}", Default=0.01, Lower=0,DisplayUnit='kPa');
    111111OutletNozzle    as press_delta  (Brief="Outlet Nozzle Pressure Drop", Symbol = "\Delta P_{Nozzle\_Out}", Default=0.01, Lower=0,DisplayUnit='kPa');
    112 Total                           as press_delta  (Brief="Total Pressure Drop", Symbol = "\Delta P_{total}", Default=0.01, Lower=1E-10,DisplayUnit='kPa');
    113 Vnozzle_in              as velocity             (Brief="Inlet Nozzle Velocity", Symbol = "V_{Nozzle\_In}", Default=1, Upper=1e5, Lower=0);
    114 Vnozzle_out     as velocity             (Brief="Outlet Nozzle Velocity", Symbol = "V_{Nozzle\_Out}", Default=1, Upper=1E5, Lower=0);
     112Total                           as press_delta  (Brief="Total Pressure Drop", Symbol = "\Delta P_{total}", Default=0.01, Lower=0,DisplayUnit='kPa');
     113Vnozzle_in              as velocity             (Brief="Inlet Nozzle Velocity", Symbol = "V_{Nozzle\_In}", Default=1, Upper=1e7, Lower=0);
     114Vnozzle_out     as velocity             (Brief="Outlet Nozzle Velocity", Symbol = "V_{Nozzle\_Out}", Default=1, Upper=1E7, Lower=0);
    115115FricFactor              as fricfactor           (Brief="Friction Factor", Symbol = "f_i", Default=0.05, Lower=1e-10, Upper=2000);
    116116
    … …  
    130130       
    131131VARIABLES
    132 Re              as positive                             (Brief="Tube Side Reynolds Number",Default=1000,Lower=1);
     132Re              as positive                             (Brief="Tube Side Reynolds Number",Default=1000,Lower=1e-3);
    133133Nu              as positive                             (Brief="Nusselt Number",Default=0.5,Lower=1e-8);
    134134htube   as heat_trans_coeff (Brief="Tube Side Film Coefficient",Default=1,Lower=1e-12, Upper=1e6);
    … …  
    248248VARIABLES
    249249
    250 DT0             as temp_delta   (Brief="Temperature Difference at Inlet",Lower=1e-6, Symbol ="\Delta T_0",Protected=true);
    251 DTL             as temp_delta   (Brief="Temperature Difference at Outlet",Lower=1e-6, Symbol ="\Delta T_L",Protected=true);
    252 LMTD    as temp_delta   (Brief="Logarithmic Mean Temperature Difference",Lower=1e-6,Protected=true);
     250DT0             as temp_delta   (Brief="Temperature Difference at Inlet",Lower=0, Symbol ="\Delta T_0",Protected=true);
     251DTL             as temp_delta   (Brief="Temperature Difference at Outlet",Lower=0, Symbol ="\Delta T_L",Protected=true);
     252LMTD    as temp_delta   (Brief="Logarithmic Mean Temperature Difference",Lower=0,Protected=true);
    253253Fc                      as positive             (Brief="LMTD Correction Factor",Lower=0.1,Protected=true);
    254254
    … …  
    286286VARIABLES
    287287A               as area                                 (Brief="Exchange Surface Area");
    288 Q               as power                                (Brief="Heat Transfer", Default=7000, Lower=1e-6, Upper=1e10);
     288Q               as power                                (Brief="Heat Transfer", Default=7000, Lower=-1e10, Upper=1e10);
    289289Uc      as heat_trans_coeff (Brief="Overall Heat Transfer Coefficient Clean",Default=1,Lower=1e-6,Upper=1e10);
    290290Ud      as heat_trans_coeff (Brief="Overall Heat Transfer Coefficient Dirty",Default=1,Lower=1e-6,Upper=1e10);

  • trunk/eml/heat_exchangers/HeatExchangerDetailed.mso

    r737 r1005  
    107107#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++#
    108108Pi                                                      as constant   (Brief="Pi Number", Hidden = true, Default=3.14159265, Symbol = "\pi");
     109pi                                                      as constant   (Brief="Pi Number", Unit = 'rad', Default=3.14159265, Symbol = "\pi");
    109110Aonozzle_Shell          as area                 (Brief="Shell Outlet Nozzle Area", Hidden = true, Lower=1E-6 ,  Symbol ="A_{nozzle\_out }^{shell}");
    110111Ainozzle_Shell          as area                 (Brief="Shell Inlet Nozzle Area", Hidden = true, Lower=1E-6 ,  Symbol ="A_{nozzle\_in }^{shell}");
    … …  
    130131#"Pi Number"
    131132        Pi      = 3.14159265;
     133        pi = Pi * 'rad';
    132134
    133135#"Baffle cut angle in degrees"
    134         Ods     = (360/Pi)*acos(1-0.02*Baffles.BaffleCut);
     136        Ods     = (360/pi)*acos(1-0.02*Baffles.BaffleCut);
    135137
    136138#"Baffle cut angle relative to the centerline"
    137         Octl    = (360/Pi)*acos((Shell.ShellID/(Shell.ShellID - Clearances.BundleToShell - Tubes.TubeOD))*(1-0.02*Baffles.BaffleCut));
     139        Octl    = (360/pi)*acos((Shell.ShellID/(Shell.ShellID - Clearances.BundleToShell - Tubes.TubeOD))*(1-0.02*Baffles.BaffleCut));
    138140
    139141#"Fraction of number of tubes in baffle window"
    140         Ftw     = (Octl/360)-sin(Octl*Pi/180)/(2*Pi);
     142        Ftw     = (Octl/360)-sin(Octl*pi/180)/(2*Pi);
    141143
    142144#"Shell to baffle leakage area"
    … …  
    150152
    151153#"comments"
    152         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);
     154        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);
    153155
    154156#"Tube Side Inlet Nozzle Area"
    … …  
    180182"Shell Stream Average Temperature"
    181183        Shell.Properties.Average.T = 0.5*InletShell.T + 0.5*OutletShell.T;
     184#       Shell.Properties.Average.T = InletShell.T;
    182185       
    183186"Tube Stream Average Temperature"
    184187        Tubes.Properties.Average.T = 0.5*InletTube.T + 0.5*OutletTube.T;
     188#       Tubes.Properties.Average.T = InletTube.T;
    185189       
    186190"Shell Stream Average Pressure"
    187         Shell.Properties.Average.P = 0.5*InletShell.P+0.5*OutletShell.P;
     191#       Shell.Properties.Average.P = 0.5*InletShell.P+0.5*OutletShell.P;
     192        Shell.Properties.Average.P = InletShell.P;
    188193       
    189194"Tube Stream Average Pressure"
    190         Tubes.Properties.Average.P = 0.5*InletTube.P+0.5*OutletTube.P;
     195#       Tubes.Properties.Average.P = 0.5*InletTube.P+0.5*OutletTube.P;
     196        Tubes.Properties.Average.P = InletTube.P;
    191197       
    192198"Shell Stream Average Molecular Weight"
    … …  
    355361
    356362"Mass Velocity in Window Zone"
    357         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))));
     363        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))));
    358364
    359365switch TubeFlowRegime
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