Changeset 386 for trunk/eml

Timestamp:

Oct 10, 2007, 5:45:23 PM (16 years ago)

Author:

gerson bicca

Message:

updated PHE model

Location:

trunk/eml/heat_exchangers

Files:

• HEX_Engine.mso (modified) (1 diff)
• PHE.mso (modified) (6 diffs)

trunk/eml/heat_exchangers/HEX_Engine.mso

@@ -449 +449 @@
 end
 
-Model Thermal_PHE as LMTD_Basic
+Model Thermal_PHE
 
 ATTRIBUTES

trunk/eml/heat_exchangers/PHE.mso

@@ -54 +54 @@
 
 == Setting The PHE Option Parameters ==
-*Method: NTU or LMTD
 *SideOne: cold or hot
 
@@ -72 +71 @@
 outer NComp             as Integer      (Brief="Number of Chemical Components");
         Pi                              as constant     (Brief="Pi Number",Default=3.14159265, Symbol = "\pi");
-        Kp1(15)                 as constant     (Brief="First constant in Kumar calculation for Pressure Drop");
-        Kp2(15)                 as constant     (Brief="Second constant in Kumar calculation for Pressure Drop");
-        Kc1(14)                 as constant     (Brief="First constant in Kumar calculation for Heat Transfer");
-        Kc2(14)                 as constant     (Brief="Second constant Kumar calculation for Heat Transfer");
+        N1                      as Integer      (Brief="Auxiliar Constant");
+        N2                      as Integer      (Brief="Auxiliar Constant");
+        Kp1(N1)                 as constant     (Brief="First constant in Kumar calculation for Pressure Drop");
+        Kp2(N1)                 as constant     (Brief="Second constant in Kumar calculation for Pressure Drop");
+        Kc1(N2)                 as constant     (Brief="First constant in Kumar calculation for Heat Transfer");
+        Kc2(N2)                 as constant     (Brief="Second constant Kumar calculation for Heat Transfer");
         M(NComp)                as molweight    (Brief="Component Mol Weight");
         
         ChevronAngle    as Switcher             (Brief="Chevron Corrugation Inclination Angle in Degrees ",Valid=["30 Deg","45 Deg","50 Deg","60 Deg","65 Deg"],Default="30 Deg");
-        Method                  as Switcher             (Brief="Method of Thermal Calculation",Valid=["NTU","LMTD"],Default="NTU");
         SideOne                 as Switcher             (Brief="Fluid Alocation in the Side I - (The odd channels)",Valid=["hot","cold"],Default="hot");
         Nchannels               as Integer              (Brief="Total Number of Channels in The Whole Heat Exchanger");
@@ -115 +115 @@
 
  SET
+#"Vector Length of constants for Kumar's calculating Pressure Drop"
+        N1 = 15;
+
+#"Vector Length of constants for Kumar's calculating Heat Transfer"
+        N2 = 14;
 
 #"First constant for Kumar's calculating Pressure Drop"
@@ -147 +152 @@
 
 #"Ports Area"
-        Aports=Pi*Dports*Dports/4;
+        Aports=0.25*Pi*Dports*Dports;
         
 #"Channel Area"
@@ -659 +664 @@
         Thermal.Ud*(1/HotSide.HeatTransfer.hcoeff +pt/Kwall+1/ColdSide.HeatTransfer.hcoeff + Rfc + Rfh)=1;
 
- switch Method
-        
-        case "LMTD":
-        
-"Duty"
-        Thermal.Q = Thermal.Ud*Atotal*Thermal.LMTD*Thermal.Fc;
-        
-        case "NTU":
-
-"Duty"
+ "Duty"
         Thermal.Q = Thermal.Eft*Thermal.Cmin*(InletHot.T-InletCold.T);
 
- end
-
-"Temperature Difference at Inlet - Counter Flow"
-        Thermal.DT0 = InletHot.T - OutletCold.T;
-
-"Temperature Difference at Outlet - Counter Flow"
-        Thermal.DTL = OutletHot.T - InletCold.T;
-
-"Heat Capacity Ratio"
+ "Heat Capacity Ratio"
         Thermal.Cr =Thermal.Cmin/Thermal.Cmax;
 
@@ -703 +691 @@
         ColdSide.HeatTransfer.NTU*ColdSide.HeatTransfer.WCp = Thermal.Ud*Atotal;
 
- if Thermal.Cr equal 1 # To be Fixed: Effectiveness in true counter flow !
+if Thermal.Cr equal 1 # To be Fixed: Effectiveness in true counter flow !
         
         then
 "Effectiveness in Counter Flow"
-        Thermal.Eft = Thermal.NTU/(1+Thermal.NTU);
-        
-"LMTD Correction Factor"
-        Thermal.Fc =Thermal.Eft/(1.0001-Thermal.Eft)/Thermal.NTU;
+        Thermal.Eft*(1+Thermal.NTU) = Thermal.NTU;
         
         else
 "Effectiveness in Counter Flow"
-        Thermal.Eft = (1-exp(-Thermal.NTU*(1-Thermal.Cr)))/(1-Thermal.Cr*exp(-Thermal.NTU*(1-Thermal.Cr)));
-
-"LMTD Correction Factor"
-        Thermal.Fc =(ln(abs(1-Thermal.Eft*Thermal.Cr))-ln(abs(1-Thermal.Eft)))/(Thermal.NTU*(1-Thermal.Cr));
-        
- end
+        Thermal.NTU = (1/(Thermal.Cr-1))*ln(abs((Thermal.Eft-1)/(Thermal.Cr*Thermal.Eft-1)));
 
 end
+
+end