L(791)
  DISPLAY
    Transient analysis of a counter-flow heat-exchanger with
    allowance for the thermal capacity of the metal.
    This Q1 contains PHOTNON USE commands.
  ENDDIS
  PHOTON USE
  p
  parphi
 
 
 
  msg The computational grid. Note: z = time. Press return for T1
  gr y 1
  pause
  msg T1, 1st-fluid temperature. Note: z = time. Press return for T2
  con 1sth y 1 fi;0.05
  pause
  con off;red
  msg T2, 2nd-fluid temperature. Note: z = time. Press return for Tm
  con 2ndh y 1 fi;0.05
  pause
  con off;red
  msg Tm, metal temperature. Note: z = time. Press E to end
  con metl y 1 fi;0.05
  pause
  ENDUSE
 
    GROUP 1. Run title
TEXT(791 + Allowance For Metal Capacity
TITLE
    User-defined variables:
REAL(CAPM,COEF1O,COEF2O,COEFMO)
CAPM=0.1;COEFMO=CAPM/DELT
 
    In order to accelerate convergence a simple version of the
    "partial-elimination algorithm" is employed. This entails
    eliminating the late-time metal temperature from the
    equations for heat transfer from fluid to metal. Then each
    fluid is connected thermally with the other fluid and with
    the temperature of the early-time metal. This technique
    could be further extended with advantage.
 
    The heat-transfer resistance offered by the metal is
    accounted for implicitly in the values which are ascribed
    to COEF1 and COEF2.
 
COEF12=COEF1*COEF2/(COEF1+COEF2+COEFMO)
COEF1O=COEF1*COEFMO/(COEF1+COEF2+COEFMO)
COEF2O=COEF2*COEFMO/(COEF1+COEF2+COEFMO)
 
    Arrange that metal temperature, named METL, occupies
    store with index 1 above 2NDH and 2 above 1STH.
 
SOLVE(C1);NAME(C1)=METL;TERMS(METL,N,N,N,Y,N,N)
FIINIT(METL)=0.5*(T1IN+T2IN)
 
    Repeat the COVALs using COEF12, which has changed
    since it was calculated for case 2.
COVAL(NEPLUS,1STH,COEF12,LOCNE)
COVAL(NEMINUS,2NDH,COEF12,LOCNE)
 
    Connect shell fluid with old metal
PATCH(NEO2,VOLUME,1,NX,1,NY,1,NZ,1,LSTEP)
COVAL(NEO2,1STH,COEF1O,LOCNE)
 
    Connect metal with shell fluid
PATCH(NEM2,VOLUME,1,NX,1,NY,1,NZ,1,LSTEP)
COVAL(NEM2,METL,COEF1O,LOCNE)
 
    Connect tube fluid with old metal
PATCH(NEO1,VOLUME,1,NX,1,NY,1,NZ,1,LSTEP)
COVAL(NEO1,2NDH,COEF2O,LOCNE)
 
    Connect metal with tube fluid
PATCH(NEM1,VOLUME,1,NX,1,NY,1,NZ,1,LSTEP)
COVAL(NEM1,METL,COEF2O,LOCNE)
 
    Transient for metal
COVAL(NEOLD,METL,COEFMO,LOCNE)
 
LSWEEP=10;RESREF(METL)=RESREF(1STH)*0.1
 
    Output
OUTPUT(METL,N,N,Y,Y,Y,Y)
PLOT(PROFILES,METL,T2IN,T1IN)
PLOT(TIMEPLOT,METL,T2IN,T1IN)
NTPRIN=LSTEP/4