SF_9
Function SF_9 provides the shape factor ([m] or [ft]) for conduction between the inner and outer surfaces of a tube composed of a circle within a regular N-sided polygon.
Inputs:
d_in = diameter of inner circle ([m] or [ft])
d_out = diameter of circle inscribed in outer polygon ([m] or [ft])
L = length of tube ([m] or [ft])
N = number of sides
Example: SF = SF_9(d_in, d_out, L, N)
Reference: Laura, P & Susenmihl, E. "Determination of Heat Flow Shape Factors for Hollow, Regular Polygonal Prisms," Nuclear Engineering and Design (47): 227-229, 1978. in Rohsenow W., Harnet J. & Cho, Y. (1998). Handbook of heat transfer, 3rd ed. Madison, Wisconsin: McGraw Hill. p. 3.21.