Chapter 12, Problem 12.74P

The 50-mm peephole of a large furnace operating at ${450}^{\circ }C$ is covered with a material having $\tau =0.8$ and $\rho =0$ for irradiation originating from the furnace. The material has an emissivity of 0.8 and is opaque to irradiation from a source at room temperature. The outer surface of the cover is exposed to surroundings and ambient air at ${27}^{\circ }C$ with a convection heat transfer coefficient of $50W/m^2\cdot k$ . Assuming that convection effects on the inner surface of the cover are negligible, calculate the heat loss by the furnace and the temperature of the cover