Changeset 484


Ignore:
Timestamp:
Mar 11, 2008, 5:12:45 PM (15 years ago)
Author:
gerson bicca
Message:

Hairpin: added option to solve convergence problems from a simplified model

Location:
trunk
Files:
2 added
2 edited

Legend:

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

    r441 r484  
    4646        OuterTurbulentCorrelation   as Switcher         (Brief="Heat Transfer Correlation in Turbulent Flow for the Outer Side",Valid=["Petukhov","SiederTate"],Default="Petukhov");
    4747
     48        CalculationApproach                             as Switcher             (Brief="Options for convergence Calculations ",Valid=["Simplified","Full"],Default="Full");
     49        Qestimated                                                              as power                                (Brief="Estimated Duty", Default=70, Lower=1e-6, Upper=1e10);
     50       
    4851        Pi                              as constant             (Brief="Pi Number",Default=3.14159265, Symbol = "\pi");
    4952        DoInner         as length                       (Brief="Outside Diameter of Inner Pipe",Lower=1e-6);
     
    474477        Outer.HeatTransfer.hcoeff= (Outer.HeatTransfer.Nu*Outer.Properties.Average.K/Outer.HeatTransfer.Dh)*Outer.HeatTransfer.Phi;
    475478
     479switch CalculationApproach
     480       
     481        case "Full":
     482
    476483"Total Pressure Drop Outer Stream"
    477484        Outer.PressureDrop.Pdrop  = Outer.PressureDrop.Pd_fric+Outer.PressureDrop.Pd_ret;
     
    503510"Inner Pipe Phi correction"
    504511        Inner.HeatTransfer.Phi  = (Inner.Properties.Average.Mu/Inner.Properties.Wall.Mu)^0.14;
     512
     513        case "Simplified":
     514
     515"Total Pressure Drop Outer Stream"
     516        Outer.PressureDrop.Pdrop  = 0*'kPa';
     517
     518"Total Pressure Drop Inner Stream"
     519        Inner.PressureDrop.Pdrop  = 0*'kPa';
     520       
     521"Pressure Drop Outer Stream"
     522        OutletOuter.P  = InletOuter.P;
     523
     524"Pressure Drop Inner Stream"
     525        OutletInner.P  = InletInner.P;
     526       
     527"Outer Pipe Pressure Drop for friction"
     528        Outer.PressureDrop.Pd_fric = 0*'kPa';
     529       
     530"Inner Pipe Pressure Drop for friction"
     531        Inner.PressureDrop.Pd_fric = 0*'kPa';
     532
     533"Outer Pipe Pressure Drop due to return"
     534        Outer.PressureDrop.Pd_ret = 0*'kPa';
     535
     536"Inner Pipe Pressure Drop due to return"
     537        Inner.PressureDrop.Pd_ret = 0*'kPa';
     538
     539"Outer Pipe Phi correction"
     540        Outer.HeatTransfer.Phi = 1;
     541       
     542"Inner Pipe Phi correction"
     543        Inner.HeatTransfer.Phi  = 1;
     544
     545end
    505546
    506547"Outer Pipe Prandtl Number"
     
    549590
    550591FlowDirection   as Switcher     (Brief="Flow Direction",Valid=["counter","cocurrent"],Default="cocurrent");
    551        
     592Eftestimated            as positive     (Brief="Effectiveness estimate",Default=0.5);
     593
    552594VARIABLES
    553595
     
    555597
    556598EQUATIONS
     599
     600"Effectiveness Correction"
     601        Method.Eft1 = 1;
     602
     603switch CalculationApproach
     604
     605        case "Full":
    557606
    558607"Number of Units Transference"
     
    567616"Thermal Capacity Ratio"
    568617        Method.Cr    = Method.Cmin/Method.Cmax;
    569 
    570 "Effectiveness Correction"
    571         Method.Eft1 = 1;
    572618
    573619if Method.Cr equal 0
     
    605651end
    606652
     653        case "Simplified":
     654
     655"Number of Units Transference"
     656        Method.NTU = 1;
     657       
     658"Minimum Heat Capacity"
     659        Method.Cmin  = min([Method.Ch,Method.Cc]);
     660
     661"Maximum Heat Capacity"
     662        Method.Cmax  = max([Method.Ch,Method.Cc]);
     663
     664"Thermal Capacity Ratio"
     665        Method.Cr    = 1;
     666
     667"Effectiveness"
     668        Method.Eft = Eftestimated;
     669
     670end
     671
    607672switch HotSide
    608673       
    609674        case "outer":
     675
     676switch CalculationApproach
     677
     678        case "Full":
    610679
    611680"Duty"
    612681        Details.Q       = Method.Eft*Method.Cmin*(InletOuter.T-InletInner.T);
    613682
     683        case "Simplified":
     684
     685"Duty"
     686        Details.Q       = Qestimated;
     687
     688end
     689
    614690"Hot Stream Heat Capacity"
    615691        Method.Ch  = InletOuter.F*Outer.Properties.Average.Cp;
     
    622698        case "inner":
    623699
     700switch CalculationApproach
     701
     702        case "Full":
     703
    624704"Duty"
    625705        Details.Q       = Method.Eft*Method.Cmin*(InletInner.T-InletOuter.T);
     706
     707        case "Simplified":
     708
     709"Duty"
     710        Details.Q       = Qestimated;
     711       
     712end
    626713
    627714"Cold Stream Heat Capacity"
     
    657744EQUATIONS
    658745
    659 "Exchange Surface Area"
     746switch CalculationApproach
     747
     748        case "Full":
     749
     750"Duty"
    660751        Details.Q = Details.Ud*Pi*DoInner*(2*Lpipe)*Method.LMTD;
    661        
     752
     753        case "Simplified":
     754
     755"Duty  Estimated"
     756        Details.Q = Qestimated;
     757
     758end
     759
    662760"LMTD Correction Factor - True counter ou cocurrent flow"
    663761        Method.Fc = 1;
  • trunk/sample/heat_exchangers/Sample_hairpin.mso

    r441 r484  
    6262exchanger.OuterTurbulentCorrelation     = "SiederTate";
    6363exchanger.OuterLaminarCorrelation       = "Schlunder";
    64        
     64
     65#exchanger.CalculationApproach = "Simplified";
     66exchanger.CalculationApproach = "Full";
     67exchanger.Qestimated                                    = 4*'kW';
    6568#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
    6669# Hairpin Geometrical Parameters and Alocation
     
    99102
    100103Dynamic  = false;
    101 GuessFile = "GuessPipe";
     104GuessFile = "GuessSampleHairpin";
    102105
    103106end
     
    140143exchanger.OuterTurbulentCorrelation  = "SiederTate";
    141144exchanger.OuterLaminarCorrelation     = "Schlunder";
    142        
     145
     146#exchanger.CalculationApproach = "Simplified";
     147exchanger.CalculationApproach = "Full";
     148
     149exchanger.Qestimated                                    = 2*'kW';
     150exchanger.Eftestimated                          = 0.4;
    143151#++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
    144152# Hairpin Geometrical Parameters and Alocation
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