Changeset 120


Ignore:
Timestamp:
Jan 17, 2007, 6:11:19 PM (15 years ago)
Author:
gerson bicca
Message:

updated Mheatex model

Location:
trunk
Files:
2 edited

Legend:

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

    r100 r120  
    8484        LMTD    as temp_delta   (Brief="Logarithmic Mean Temperature Difference");
    8585        UA      as positive     (Unit="W/K");
    86 
     86        DT0     as temp_delta   (Brief="Temperature Difference at Inlet",Lower=1);
     87        DTL             as temp_delta   (Brief="Temperature Difference at Outlet",Lower=1);
     88       
    8789SET
    8890
     
    131133        Q=UA*LMTD;
    132134
    133 #+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++#
    134 #       Flow Direction
    135 #+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++#
     135       
     136if abs(DT0 - DTL) > 0.05*max(abs([DT0,DTL]))
     137       
     138        then
     139"Log Mean Temperature Difference"
     140        LMTD= (DT0-DTL)/ln(DT0/DTL);
     141
     142        else
     143       
     144if DT0*DTL equal 0
     145       
     146        then
     147"Log Mean Temperature Difference"
     148        LMTD = 0.5*(DT0+DTL);
     149       
     150        else
     151"Log Mean Temperature Difference"
     152        LMTD = 0.5*(DT0+DTL)*(1-(DT0-DTL)^2/(DT0*DTL)*(1+(DT0-DTL)^2/(DT0*DTL)/2)/12);
     153       
     154end
     155       
     156end     
     157
    136158
    137159if Side equal 0
    138160       
    139161        then
    140 "Cocurrent Flow LMTD"
    141         LMTD = HE.CocurrentLMTD(max(Inlet.Hot.T),min(Outlet.Hot.T),min(Inlet.Cold.T),max(Outlet.Cold.T));
     162       
     163"Temperature Difference at Inlet"
     164        DT0 = max(Inlet.Hot.T) - min(Inlet.Cold.T);
     165
     166"Temperature Difference at Outlet"
     167        DTL = min(Outlet.Hot.T) - max(Outlet.Cold.T);
    142168       
    143169        else
    144 "Counter Flow LMTD"
    145         LMTD = HE.CounterLMTD(max(Inlet.Hot.T),min(Outlet.Hot.T),max(Inlet.Cold.T),min(Outlet.Cold.T));
     170       
     171"Temperature Difference at Inlet"
     172        DT0 = max(Inlet.Hot.T) - max(Outlet.Cold.T);
     173
     174"Temperature Difference at Outlet"
     175        DTL = min(Outlet.Hot.T) - min(Inlet.Cold.T);
    146176       
    147177end
  • trunk/sample/heat_exchangers/MheaterTeste.mso

    r100 r120  
    5555       
    5656       
    57         Mheater.HE.FlowDirection  = "Counter";
     57        Mheater.HE.FlowDirection  = "Cocurrent";
    5858        Mheater.Ncold = 2;
    5959        Mheater.Nhot  = 2;
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