program htcoef1 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 Each of the following blocks obtains a heat transfer coefficient c from a function named "htc", that is defined after the main routine c Re=10. h=htc(Re,D,k,Pr) print *, 'For Reynolds Number = ',Re print *, 'Heat Transfer Coefficient is ',h,' w/m**2/K' c h=htc(100.,D,k,Pr) print *, 'For Reynolds Number = 100.' print *, 'Heat Transfer Coefficient is ',h,' w/m**2/K' c h=htc(1000.,D,k,Pr) print *, 'For Reynolds Number = 1000' print *, 'Heat Transfer Coefficient is ',h,' w/m**2/K' c h=htc(1.0e4,D,k,Pr) print *, 'For Reynolds Number = 10,000' print *, 'Heat Transfer Coefficient is ',h,' w/m**2/K' c stop end 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/ Nuturb=0.023*Re**0.8*Pr**0.4 c c As with any function a value must be associated with the function c name by putting the name on the left side of an "=" c htc=k/Hd*max(Nulam,Nuturb) return end