A solid sphere of radius r1 = 20 mm is placed concentrically inside a hollow sphere of radius r2 = 30 mm as shown in figure.
The view factor F21 for radiation heat transfer is
1
2/3
2
4/9
3
8/27
4
9/4
A solid sphere of radius r1 = 20 mm is placed concentrically inside a hollow sphere of radius r2 = 30 mm as shown in figure.
The view factor F21 for radiation heat transfer is