program htcoef3
c
c John Mahaffy, Penn State University, CmpSc 201 Example
c 1/26/96
c
implicit none
real k,D,h,Re,Pr
real htc
c
c Calculate an approximation for heat transfer coefficients
c in a 1 inch pipe for several different Reynolds numbers
c
c h - heat transfer coefficient ( w/m**2/K)'
c k - conductivity ( w/m/K)'
c D - hydraulic diameter (m)
c Re - Reynolds number
c
data k,D,Pr/0.617,0.0254,1.0/
c
c Calculate and print Heat Transfer Coefficients for several
c Reynolds numbers.
c
Re=10.
h=htc(Re,D,k,Pr)
call output (Re,h)
c
h=htc(100.,D,k,Pr)
call output( 100., h)
c
call output (1000.,htc(1000.,D,k,Pr))
c
h=htc(1.e4,D,k,Pr)
call output(1.0e4,h)
c
stop
end
c
function htc(Re,Hd,k,Pr)
c
c Calculate a heat transfer coefficient based on the maximum of the
c Laminar and Turbulent coefficients. The turbulent coefficient is
c obtained from a Dittus-Boelter correlation
c
implicit none
real Re,k,Hd,Pr,htc,Nulam,Nuturb
c
c htc - heat transfer coefficient ( w/m**2/K)'
c Nulam - laminar Nusselt number
c Nuturb - Turbulent Nusselt number (Dittus-Boelter correlation)
c k - conductivity ( w/m/K)'
c Hd - hydraulic diameter (m)
c Re - Reynolds number
c Pr - Prandl number
c
data Nulam / 4.0/
c
c One big advantage of isolating repeated operations in a single
c location is that you can change things quickly. Here, I'm going
c to use what I know about the "**" operator to speed the calculation
c of "Nuturb=0.023*Re**.8*Pr**0.4
c
Nuturb=0.023*exp(log(Re)*0.8+log(Pr)*0.4)
htc=k/Hd*max(Nulam,Nuturb)
return
end
c
subroutine output ( Re, h)
c Print results to the screen
c
implicit none
real Re, h
c
c Re - Reynolds Number
c h - Heat Transfer Coefficient
c
print *, 'For Reynolds Number = ',Re
print *, 'Heat Transfer Coefficient is ',h,' w/m**2/K'
return
end