Changeset 136

Timestamp:

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

Author:

gerson bicca

Message:

solved convergence problem for multitubular heat exchanger

Location:

trunk

Files:

• eml/heat_exchangers/DoublePipe.mso (modified) (2 diffs)
• sample/heat_exchangers/Double_Pipe_Multitubular.rlt (added)
• sample/heat_exchangers/Sample_Multitubular.mso (modified) (5 diffs)

trunk/eml/heat_exchangers/DoublePipe.mso

@@ -628 +628 @@
 
 "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"
@@ -793 +794 @@
 
 "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

@@ -1 +1 @@
 #++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 # 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
@@ -42 +47 @@
 Pipe.DiOuter            =       0.07793*"m";
 Pipe.Kwall              =       0.057 *"kW/m/K";
-Pipe.Lpipe                      =       3*"m";
+Pipe.Lpipe                      =       1.7*"m";
 
 SPECIFY
@@ -49 +54 @@
 #++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 
-        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;
         
 #++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
@@ -58 +64 @@
 #++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 
-        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;
         
 #++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
@@ -76 +83 @@
 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