SR_3
The function SR_3(a, k) returns the thermal resistance between the surface of a circular contact area that is exposed to a uniform heat flux and is located on the surface of a semi-infinite half-space. The resistance is based on the center temperature of the circle (SR_2 provides the resistance based on the area averaged temperature).
The calling protocol is:
R = SR_3(a, k)
Inputs:
a = radius of the circular contact [m or ft]
k = thermal conductivity of the material [W/m-K or Btu/hr-ft-R]
Outputs:
R = resistance [K/W or R-hr/Btu]
Rohsenow, W.M, J. P. Hartnett, and Y. I. Cho, Handbook of Heat Transfer, 3rd Edition, McGraw Hill, (1998).
Example:
$UnitSystem SI Mass J K Pa
$VarInfo R3 units=K/W
a=0.01 [m]
k=100 [W/m-K]
R3=sr_3(a,k)
{Solution:
R3=0.3183 [K/W]}