source: trunk/eml/heat_exchangers/Mheatex.mso @ 126

#*-------------------------------------------------------------------
* EMSO Model Library (EML) Copyright (C) 2004 - 2007 ALSOC.
*
* This LIBRARY is free software; you can distribute it and/or modify
* it under the therms of the ALSOC FREE LICENSE as available at
* http://www.enq.ufrgs.br/alsoc.
*
* EMSO Copyright (C) 2004 - 2007 ALSOC, original code
* from http://www.rps.eng.br Copyright (C) 2002-2004.
* All rights reserved.
*
* EMSO is distributed under the therms of the ALSOC LICENSE as
* available at http://www.enq.ufrgs.br/alsoc.
*
*
*---------------------------------------------------------------------
* Model of a Multistream Heat Exchanger
*
*       Streams:
*               * Hot Inlet streams ....        at least one Hot material stream
*               * Cold Inlet streams ....       at least one Cold material stream
*               * Hot Outlet streams  ....      one material stream for each Hot Inlet
*               * Cold Outlet streams  ....     one material stream for each Cold Inlet
*
*       Purpose:
*               * Heat Transfer between multiple hot and cold streams.
*
*----------------------------------------------------------------------
* Author: Gerson Balbueno Bicca 
* $Id: Mheatex.mso 122 2007-01-18 16:06:09Z bicca $
*--------------------------------------------------------------------*#

using "streams.mso";

Model Inlet_Main_Stream         
#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++#
#       Inlet Streams
#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++#
PARAMETERS

        Ncold   as Integer      (Brief="Number of Inlet Cold Streams",Lower=1);
        Nhot    as Integer      (Brief="Number of Inlet Hot Streams",Lower=1);
        
VARIABLES

        Hot  (Nhot)     as stream;# Inlet Hot Streams
        Cold (Ncold)    as stream;# Inlet Cold Streams
        
end

Model Outlet_Main_Stream        
#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++#
#       Outlet Streams
#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++#
PARAMETERS

        Ncold   as Integer      (Brief="Number of Inlet Cold Streams",Lower=1);
        Nhot    as Integer      (Brief="Number of Inlet Hot Streams",Lower=1);
        
VARIABLES

        Hot  (Nhot)     as stream_therm;# Outlet Hot Streams
        Cold (Ncold)    as stream_therm;# Outlet Cold Streams
        
end

Model Mheatex
#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++#
#       Multistream Heat Exchanger Basic Calculation
#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++#
PARAMETERS

ext PP          as CalcObject   (Brief="Physical Properties");
ext     NComp   as Integer              (Brief="Number of Components"); 
        HE              as CalcObject   (Brief="Cold Box Calculations",File="heatex");
        Side    as Integer              (Brief="Flow Direction",Lower=0,Upper=1);
        Ncold   as Integer              (Brief="Number of Inlet Cold Streams",Lower=1);
        Nhot    as Integer              (Brief="Number of Inlet Hot Streams",Lower=1);
        
VARIABLES

in  Inlet       as Inlet_Main_Stream;           # Inlet Hot Streams
out Outlet      as Outlet_Main_Stream;          # Outlet Hot Streams

        Q       as power                (Brief="Heat Transfer");
        LMTD    as temp_delta   (Brief="Logarithmic Mean Temperature Difference");
        UA      as positive     (Unit="W/K");
        DT0     as temp_delta   (Brief="Temperature Difference at Inlet",Lower=1);
        DTL             as temp_delta   (Brief="Temperature Difference at Outlet",Lower=1);
        
SET

# Flow Direction
        Side = HE.FlowDir();

# Inlet Ncold Parameters
        Inlet.Ncold  = Ncold;
        
# Outlet Ncold Parameters
        Outlet.Ncold = Ncold;

# Inlet Nhot Parameters
        Inlet.Nhot  = Nhot;
        
# Outlet Nhot Parameters
        Outlet.Nhot = Nhot ;

EQUATIONS

"Hot Flow"
        Outlet.Hot.F = Inlet.Hot.F;     

"Cold Flow"
        Outlet.Cold.F = Inlet.Cold.F;
        
"Hot Composition"
        Outlet.Hot.z = Inlet.Hot.z;
        
"Cold Composition"
        Outlet.Cold.z = Inlet.Cold.z;
        


for i in [1:Nhot]

"Vapourisation Fraction Hot Stream"
        Outlet.Hot(i).v = PP.VapourFraction(Outlet.Hot(i).T,Outlet.Hot(i).P,Outlet.Hot(i).z);           
        
end     


for j in [1:Ncold]
        
"Vapourisation Fraction Cold Stream"
        Outlet.Cold(j).v = PP.VapourFraction(Outlet.Cold(j).T,Outlet.Cold(j).P,Outlet.Cold(j).z);
        
end
        

"Heat Duty Hot Stream"
        Q =  sum(Inlet.Hot.F*(Inlet.Hot.h- Outlet.Hot.h));
        
"Heat Duty Cold Stream"
        Q = -sum(Inlet.Cold.F*(Inlet.Cold.h- Outlet.Cold.h));
        
"Heat Duty"
        Q=UA*LMTD;

        
if abs(DT0 - DTL) > 0.05*max(abs([DT0,DTL])) 
        
        then
"Log Mean Temperature Difference"
        LMTD= (DT0-DTL)/ln(DT0/DTL);

        else
        
if DT0*DTL equal 0
        
        then
"Log Mean Temperature Difference"
        LMTD = 0.5*(DT0+DTL);
        
        else
"Log Mean Temperature Difference"
        LMTD = 0.5*(DT0+DTL)*(1-(DT0-DTL)^2/(DT0*DTL)*(1+(DT0-DTL)^2/(DT0*DTL)/2)/12);
        
end
        
end     


if Side equal 0 
        
        then
        
"Temperature Difference at Inlet"
        DT0 = max(Inlet.Hot.T) - min(Inlet.Cold.T);

"Temperature Difference at Outlet"
        DTL = min(Outlet.Hot.T) - max(Outlet.Cold.T);
        
        else
        
"Temperature Difference at Inlet"
        DT0 = max(Inlet.Hot.T) - max(Outlet.Cold.T);

"Temperature Difference at Outlet"
        DTL = min(Outlet.Hot.T) - min(Inlet.Cold.T);
        
end

end