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