Problem 2.255

Solve the foregoing problem for the case of two concentric spheres of radii $R_{1}$ and $R_{2}$ and temperatures $T_{1}$ and $T_{2}$ .

T=T_{1}+\frac{T_{2}-T_{1}}{1 / R_{1}-1 / R_{2}}\left(\frac{1}{R_{1}}-\frac{1}{r}\right)

Transport Phenomena