Determine the steady-state temperatures of two radiation shields placed in the evacuated space between two infinite planes at temperatures of 555 K and 278 K. The emissivity of all surfaces is 0.8.
GIVEN
-Two radiant shields placed in the evacuated space between two infinite planes
-Temperature of the planes
-T1 = 555 K
-T4 = 278 K
-Emissivity of all surface (?) = 0.8
FIND
-The steady state temperatures of the shields (T2, T3)
ASSUMPTIONS
• All surfaces are gray and diffuse
SKETCH
Since the space is evacuated, convection and conduction are negligible. Since the surfaces are simply infinite planes, equivalent conductance A1 f12 can be used.
The net rate of heat transfer from A1 to A2 is
For steady state q12 = q23 = q34
Also, because of all the emittances and areas are identical
Therefore
Solving for Eb2
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