Changeset 484 for trunk/eml

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

File:

• trunk/eml/heat_exchangers/Hairpin.mso (modified) (9 diffs)

trunk/eml/heat_exchangers/Hairpin.mso

@@ -46 +46 @@
         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);
@@ -474 +477 @@
         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;
@@ -503 +510 @@
 "Inner Pipe Phi correction"
         Inner.HeatTransfer.Phi  = (Inner.Properties.Average.Mu/Inner.Properties.Wall.Mu)^0.14;
+
+        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';
+
+"Outer Pipe Pressure Drop due to return"
+        Outer.PressureDrop.Pd_ret = 0*'kPa';
+
+"Inner Pipe Pressure Drop due to return"
+        Inner.PressureDrop.Pd_ret = 0*'kPa';
+
+"Outer Pipe Phi correction"
+        Outer.HeatTransfer.Phi = 1;
+        
+"Inner Pipe Phi correction"
+        Inner.HeatTransfer.Phi  = 1;
+
+end
 
 "Outer Pipe Prandtl Number"
@@ -549 +590 @@
 
 FlowDirection   as Switcher     (Brief="Flow Direction",Valid=["counter","cocurrent"],Default="cocurrent");
-        
+Eftestimated            as positive     (Brief="Effectiveness estimate",Default=0.5);
+
 VARIABLES
 
@@ -555 +597 @@
 
 EQUATIONS
+
+"Effectiveness Correction"
+        Method.Eft1 = 1;
+
+switch CalculationApproach
+
+        case "Full":
 
 "Number of Units Transference"
@@ -567 +616 @@
 "Thermal Capacity Ratio"
         Method.Cr    = Method.Cmin/Method.Cmax;
-
-"Effectiveness Correction"
-        Method.Eft1 = 1;
 
 if Method.Cr equal 0 
@@ -605 +651 @@
 end
 
+        case "Simplified":
+
+"Number of Units Transference"
+        Method.NTU = 1;
+        
+"Minimum Heat Capacity"
+        Method.Cmin  = min([Method.Ch,Method.Cc]);
+
+"Maximum Heat Capacity"
+        Method.Cmax  = max([Method.Ch,Method.Cc]);
+
+"Thermal Capacity Ratio"
+        Method.Cr    = 1;
+
+"Effectiveness"
+        Method.Eft = Eftestimated;
+
+end
+
 switch HotSide
         
         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;
@@ -622 +698 @@
         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"
@@ -657 +744 @@
 EQUATIONS
 
-"Exchange Surface Area"
+switch CalculationApproach
+
+        case "Full":
+
+"Duty"
         Details.Q = Details.Ud*Pi*DoInner*(2*Lpipe)*Method.LMTD;
-        
+
+        case "Simplified":
+
+"Duty  Estimated"
+        Details.Q = Qestimated;
+
+end
+
 "LMTD Correction Factor - True counter ou cocurrent flow"
         Method.Fc = 1;