A long conduit is constructed with diffuse, gray walls (0.5 mathrm{~m}) wide. The top and bottom of

Question:

A long conduit is constructed with diffuse, gray walls $0.5 \mathrm{~m}$ wide. The top and bottom of the conduit are insulated. The emissivities of the walls are $\varepsilon_{1}=0.45, \varepsilon_{2}=0.65$, and $\varepsilon_{3}=0.15$, respectively, while the temperatures of walls 1 and 2 are $500 \mathrm{~K}$ and $700 \mathrm{~K}$, respectively.

(a) Determine the temperature of the insulated walls.

(b) Determine the net radiation heat rate from surface 2 per unit conduit length.
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