Heat transfer from air in pipe to outside air; v149.htm


 TALK=F;RUN( 1, 1)
 ************************************************************
   Q1 created by VDI menu, Version 3.5, Date 10/02/03
 CPVNAM=VDI;SPPNAM=Core
 ************************************************************
  Echo DISPLAY / USE settings
  DISPLAY
  Heat transfer from air in pipe to outside air

  This case simulates a heat transfer by convection about
  a single heated pipe which is described by a cylinder object.

  The pipe is cooled by a air flow of which moves
  in the X direction from left to right.

  The hot heat-transport medium a included in pipe has the Thot
  temperature. The temperatures of pipe wall is TEM1.
  Nu = 4.364 for a constant heat flux from hot air to the pipe wall.

  The In-Form is used for the setting of a heating source at PIPE
  VR object as
 
   (SOURCE of TEM1 at PIPE is :QFlux: with WHOLOB!LINE)

  where the heat flux from hot air to cold air through a pipe wall is
  QFlux=:U:*:ArOu:*(:Thot:-TEM1)

  the heat transfer coefficient from hot air to a pipe wall is
  U=1./(ArOu/(Alfa*ArIn)+1./(CondS/Thick))

  and the heat exchange coefficient from hot air to a pipe wall is
  Alfa=Nu*CondA/(2.*RadIn)

  The Q1 contains PHOTON USE commands
  ENDDIS
  PHOTON USE
  p
 
 
 
  con tem1 z 1 fi;0.0001
  enduse
 ************************************************************
 IRUNN   =       1 ;LIBREF =       149
 ************************************************************
  Group 1. Run Title
 TEXT(Heat transfer from air in pipe to outside air
  Group 2. Transience
 STEADY  =    T
  Groups 3, 4, 5  Grid Information
    * Overall number of cells, RSET(M,NX,NY,NZ,tolerance)
 RSET(M,80,40,1)
  Group 7. Variables: STOREd,SOLVEd,NAMEd
 ONEPHS  =    T
    * Non-default variable names
 NAME(149) =PRPS ; NAME(150) =TEM1
    * Solved variables list
 SOLVE(P1  ,U1  ,V1  ,TEM1)
    * Stored variables list
 STORE(PRPS)
    * Additional solver options
 SOLUTN(P1  ,Y,Y,Y,N,N,Y)
 SOLUTN(TEM1,Y,Y,Y,N,N,Y)
  Group 9. Properties
 PRESS0  = 1.000000E+05 ;TEMP0  = 2.730000E+02
 SETPRPS(1,  0)
 ENUT    = 0.000000E+00
 DVO1DT  = 3.410000E-03
 PRNDTL(TEM1) = -2.580000E-02
 EMISS   = 0.000000E+00 ;SCATT  = 0.000000E+00
  Group 11.Initialise Var/Porosity Fields
 FIINIT(PRPS) = -1.000000E+00
  Group 13. Boundary & Special Sources
  INFORM13BEGIN
  Echo InForm settings for Group 13
   Pi: Pi number
 REAL(Pi); Pi=3.14159
  PLEN: Pipe length
 REAL(PLEN); PLEN=0.1
   RadOu: The outside radius of the pipe
 REAL(RadOu); RadOu=0.02
   RadIn: The inside radius of the pipe
 REAL(RadIn); RadIn=0.015
   ArOu: The area of outside pipe surface   
 REAL(ArOu);  ArOu=2*Pi*RadOu*PLEN
   ArIn: The area of inside pipe surface   
 REAL(ArIn);  ArIn=2*Pi*RadIn*PLEN
   Thick: The thickness of a pipe wall   
 REAL(Thick);  Thick=RadOu-RadIn
   CondA: The thermal conductivity of the air
 REAL(CondA); CondA=0.0258
   CondS: The thermal conductivity of the steel
 REAL(CondS); CondS=43.
   Nu = 4.364 for a constant heat flux from hot air to the pipe wall.
 REAL(Nu); Nu=4.364
   Alfa: The heat exchange coefficient from hot air to a pipe wall
 REAL(Alfa); Alfa=Nu*CondA/(2.*RadIn)
   U: The heat transfer coefficient from hot air to a pipe wall
 REAL(U); U=1./(ArOu/(Alfa*ArIn)+1./(CondS/Thick))
   Thot: The average temperature of hot air inside a pipe
 REAL(Thot); Thot=50 
   QFlux: The heat flux from hot air to cold air through a pipe wall
 CHAR(QFlux); QFlux=:U:*:ArOu:*(:Thot:-TEM1)
          where TEM1 is the temperature of a pipe wall
 QFlux
 (SOURCE of TEM1 at PIPE is :QFlux: with WHOLOB!LINE)
   REYNO: Reynolds number
 REAL(REYNO,WIN,DIAM); WIN=0.01; DIAM=2*RadOu; REYNO=WIN*DIAM/ENUL
 REYNO
   PRANDT: Prandtl number
 REAL(PRANDT); PRANDT=CP1*ENUL*RHO1/CondA
 PRANDT
   NUSN: Nusselt number by 0.3*REYNO**0.6*PRANDT**(1/3) formula
 REAL(NUSN); NUSN=0.3*REYNO**0.6*PRANDT**(1/3)
 NUSN
  INFORM13END
  Group 15. Terminate Sweeps
 LSWEEP  =     200
 RESFAC  = 1.000000E-03
  Group 16. Terminate Iterations
 LITER (TEM1) =       400
 ENDIT (TEM1) =  1.000000E-06
  Group 17. Relaxation
 RELAX(TEM1  ,LINRLX, 5.000000E-01)
  Group 20. Preliminary Printout
 DISTIL  =    T
 EX    (P1  ) =  4.457000E-05 ;EX    (U1  ) =  1.004000E-02
 EX    (V1  ) =  9.968000E-04 ;EX    (PRPS) =  6.637000E+00
 EX    (TEM1) =  2.349000E+01
  Group 22. Monitor Print-Out
 IXMON   =      29 ;IYMON  =      20 ;IZMON  =       1
 TSTSWP  =      -1
 
 GVIEW(P,0.000000E+00,0.000000E+00,1.000000E+00)
 GVIEW(UP,0.000000E+00,1.000000E+00,0.000000E+00)
 
> DOM,    SIZE,        2.000000E-01, 1.000000E-01, 1.000000E-01
> DOM,    MONIT,       7.125000E-02, 4.925000E-02, 5.100000E-02
> DOM,    SCALE,       1.000000E+00, 1.000000E+00, 1.000000E+00
> DOM,    SNAPSIZE,    1.000000E-02
 
> OBJ,    NAME,        INLET
> OBJ,    POSITION,    0.000000E+00, 0.000000E+00, 0.000000E+00
> OBJ,    SIZE,        0.000000E+00, 1.000000E-01, 1.000000E-01
> OBJ,    CLIPART,     cube3t
> OBJ,    ROTATION24,        1
> OBJ,    TYPE,        INLET
> OBJ,    PRESSURE,      0.000000E+00
> OBJ,    VELOCITY,      1.000000E-02, 0.000000E+00, 0.000000E+00
> OBJ,    TEMPERATURE,   1.800000E+01
 
> OBJ,    NAME,        OUTLET
> OBJ,    POSITION,    2.000000E-01, 0.000000E+00, 0.000000E+00
> OBJ,    SIZE,        0.000000E+00, 1.000000E-01, 1.000000E-01
> OBJ,    CLIPART,     cube12t
> OBJ,    ROTATION24,        1
> OBJ,    TYPE,        OUTLET
> OBJ,    PRESSURE,      0.000000E+00
> OBJ,    TEMPERATURE,  -1.026000E+04
> OBJ,    COEFFICIENT,   1.000000E+03
 
> OBJ,    NAME,        PIPE
> OBJ,    POSITION,    3.000000E-02, 3.000000E-02, 0.000000E+00
> OBJ,    SIZE,        4.000000E-02, 4.000000E-02, 1.000000E-01
> OBJ,    CLIPART,     cylinder
> OBJ,    ROTATION24,        1
> OBJ,    TYPE,        BLOCKAGE
> OBJ,    MATERIAL,      111
STOP