Consider coaxial, parallel, black disks separated a listance of

0.20m

. The upper disk of diameter

0.2m

is quipped with an electric heater on the back side while the ower disk of diameter

0.40m

is maintained at

500K

and the surroundings are at

300K

.\ a) Determine the shape factors

F_(12)

(between upper and lower disks) and

F_(13)

(between upper disk and the surrounding) using the chart and the summation rule, ie

F_(11)+F_(12)+F_(13)=1

.\ b) What temperature will the upper disk attain in equilibrium if electrical power of

P_(e)=17.5W

is supplied to the heater on the back side of the disk\ Note that radiation is exchanged between the upper disk and lower disk and surrounding so that the total radiation leaving the upper disk is

Q_(rad )=Q_(upper-lower )+Q_(upper-surrounding )

\ Also from 1st law of thermodynamics:\

-Q_(rad )+W_(e)=0 so that Q_(rad )=P_(e)

R.2) (30p) Consider coaxial, parallel, black disks separated a listance of 0.20m. The upper disk of diameter 0.2m is :quipped with an electric heater on the back side while the ower disk of diameter 0.40m is maintained at 500K and the surroundings are at 300K. a) (15p) Determine the shape factors F12 (between upper and lower disks) and F13 (between upper disk and the surrounding) using the chart and the summation rule, ie F11+F12+F13=1. Note that radiation is exchanged between the upper disk and lower disk and surrounding so that the total radiation leaving the upper disk is b) (15p) What temperature will the upper disk attain in Qrad=Qupper-lower+Qupper-surrounding equilibrium if electrical power of Pee=17.5W is supplied to the heater on the back side of the disk Also from 1st law of thermodynamics: Qrad+We=0sothatQrad=Pe