# Changeset 472 for trunk/eml

Ignore:
Timestamp:
Mar 6, 2008, 8:43:11 PM (14 years ago)
Message:

Double Pipe: added option to solve convergence problems from a simplified model

File:
1 edited

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

 r442 OuterTurbulentCorrelation   as Switcher         (Brief="Heat Transfer Correlation in Turbulent Flow for the Outer Side",Valid=["Petukhov","SiederTate"],Default="Petukhov"); CalculationApproach                             as Switcher             (Brief="Options for convergence Calculations ",Valid=["Simplified","Full"],Default="Full"); Qestimated                                                              as power                                (Brief="Estimated Duty", Default=70, Lower=1e-6, Upper=1e10); Pi                              as constant             (Brief="Pi Number",Default=3.14159265, Symbol = "\pi"); DoInner         as length                       (Brief="Outside Diameter of Inner Pipe",Lower=1e-6); Outer.HeatTransfer.hcoeff= (Outer.HeatTransfer.Nu*Outer.Properties.Average.K/Outer.HeatTransfer.Dh)*Outer.HeatTransfer.Phi; switch CalculationApproach case "Full": "Total Pressure Drop Outer Stream" Outer.PressureDrop.Pdrop  = Outer.PressureDrop.Pd_fric+Outer.PressureDrop.Pd_ret; Outer.PressureDrop.Pdrop  = Outer.PressureDrop.Pd_fric; "Total Pressure Drop Inner Stream" Inner.PressureDrop.Pdrop  = Inner.PressureDrop.Pd_fric+Inner.PressureDrop.Pd_ret; Inner.PressureDrop.Pdrop  = Inner.PressureDrop.Pd_fric; "Pressure Drop Outer Stream" "Inner Pipe Pressure Drop for friction" Inner.PressureDrop.Pd_fric = (2*Inner.PressureDrop.fi*Lpipe*Inner.Properties.Average.rho*Inner.HeatTransfer.Vmean^2)/(DiInner*Inner.HeatTransfer.Phi); case "Simplified": "Total Pressure Drop Outer Stream" Outer.PressureDrop.Pdrop  = 0*'kPa'; "Total Pressure Drop Inner Stream" Inner.PressureDrop.Pdrop  = 0*'kPa'; "Pressure Drop Outer Stream" OutletOuter.P  = InletOuter.P; "Pressure Drop Inner Stream" OutletInner.P  = InletInner.P; "Outer Pipe Pressure Drop for friction" Outer.PressureDrop.Pd_fric = 0*'kPa'; "Inner Pipe Pressure Drop for friction" Inner.PressureDrop.Pd_fric = 0*'kPa'; end "Outer Pipe Pressure Drop due to return" case "outer": switch CalculationApproach case "Full": "Duty" Details.Q       = Method.Eft*Method.Cmin*(InletOuter.T-InletInner.T); case "Simplified": "Duty" Details.Q       = Qestimated; end "Hot Stream Heat Capacity" Method.Ch  = InletOuter.F*Outer.Properties.Average.Cp; case "inner": switch CalculationApproach case "Full": "Duty" Details.Q       = Method.Eft*Method.Cmin*(InletInner.T-InletOuter.T); case "Simplified": "Duty" Details.Q       = Qestimated; end "Cold Stream Heat Capacity" EQUATIONS "Exchange Surface Area" switch CalculationApproach case "Full": "Duty" Details.Q = Details.Ud*Pi*DoInner*Lpipe*Method.LMTD; case "Simplified": "Duty" Details.Q = Qestimated; end "LMTD Correction Factor - True counter ou cocurrent flow" Method.Fc = 1;
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