Hi guy!

I have a question about radiant beam length for intertube radiation conductance.
Are there any excel function for calculate radiant beam length like babcock & wilcox book, see chapter 22 - Fig.7 from Steam / its generation and use.

I try this equation below, but the result is diferent.
L/Do = (3.4/12)*((STD*SLD*Do^2)-(PI*(Do^2)/4))/(PI*Do)
or
L = [(4x0.85)/(12*PI*Do)]*[(ST*SL)-(PI*Do^2/4)]

where:
STD = ST/Do
SLD = SL/Do