# Three surfaces form a 3-surface enclosure. The surfaces have the following properties. Surface 1: A1 = 1 m2. F11 = 0. F12 = 0. T1 = 300 K. Surface 2:…

Three surfaces form a 3-surface enclosure. The surfaces have the following properties. Surface

1: A1 = 1 m2. F11 = 0. F12 = 0.2. T1 = 300 K.

Surface 2: A2 = 0.8 m2. F22 = 0. T2 = 400 K.

Surface 3: F32 = 0.3.

All temperatures are constant and uniform.

a. Determine all unknown view (shape) factors and areas. [4]

b. Determine the rate of heat transfer between surface 1 and 2, q12 if all three surfaces are

black bodies. [2]

c. Determine the temperature of surface 3, T3, if all three surfaces are black bodies and the

net rate of heat transfer from surface 3 is q3 = 2018 W. [3]

For parts d, e, f and g assume all three surfaces are grey bodies with emissivities of ε1 = 0.1, ε2

= 0.5 and ε3 = 0.7. q”3 = 1009 W/m2 and J3 = 5555 W/m2.

d. Determine the radiosities of surface 1 and surface 2. [7]

e. Determine the rate of heat transfer between surface 1 and 3, q13. [1]

f. Determine the net rate of heat transfer from surface 1. [1]

g. Determine the temperature of surface 3, T3. [2]