A drying oven consists of a long semicircular duct of diameter $D=1m.$

Materials to be dried cover the base of the oven while the wall is maintained at $1200K.$ Blackbody behavior may be assumed for theater

surface and the oven wall

Question $7$

The view factore $F_{12}$ is:

$0\mathrm{.}363$

$0\mathrm{.}637$

$1$

$0$

Question $8$

Assume that $F_{12}$ is $0\mathrm{.}9,$ the net radiation heat transfer from the oven wall to the wet material per unit length of the duct, in $k\frac{W}{m},$ is

$165\mathrm{.}4$

$117\mathrm{.}0$

$8\mathrm{.}632$

$3\mathrm{.}219$