Calculated thermal conductance for radial flow of a spherical sheel of inner and outer radius `r_(1)`and `r_(2)`. Assume that thermal conductivity of the material is `K`

Answer

`(4pikr_(1)r_(2))/((r_(2)-r_(1)))`

Explanation

`int dR = overset(r_(2))underset(r_(1))int (dR)/(4pir^(2)k)`

`R = ((r_(2)-r_(1)))/(4pir_(1)r_(2)k)`
`G = (1)/(R ) = (4pi r_(1)r_(2)k)/((r_(2)-r_(1)))`