12.84 A radiation detector having a sensitive area of Ad=4×10^(-6) m^2 is config

Question

12.84 A radiation detector having a sensitive area of Ad=4×10^(-6) m^2 is configured to receive radiation from a target area of diameter Dt=40 mm when located a distance of Lt=1 m from the target. For the experimental apparatus shown in the sketch, we wish to determine the emitted radiation from a hot sample of diameter Ds=20 mm. The temperature of the aluminum sample is Ts=700 K and its emissivity is es=0.1. A ring-shaped cold shield is provided to minimize the effect of radiation from outside the sample area, but within the target area. The sample and the shield are diffuse emitters. Assuming the shield is black, at what temperature, Tsh, should the shield be maintained so that its emitted radiation is 1% of the total radiant power received by the detector?

Tsh should be 134 K. This is Prob 12.84 from "Fundamentals of Heat and Mass Transfer" 6th Ed. by Incropera, etal.

Explanation / Answer

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