Question

124 3 RADIATIVE PROPERTIES OF REAL SURFACES 3.3 For optimum performance a solar collector surface has been treated so that, for the spectral, directional emittance < 45° 0> 45° λ<2 μm, 0 0.9 cos 20, 0.0 all 0, λ> 2 μη. 0.1, For solar incidence of 15° off-normal and a collector temperature of 400 K, what is the relevant ratio of absorptance to emittance? 3.4) A long, cylindrical antenna of 1 cm radius on an whose emittance is Earth-orbiting satellite is coated with a material λ< 1 μm, λ21 μη. Find the absorbed energy per meter length. (Assume irradiation is from the sun only, and in a 0, e=coso, (6 direction normal to the antenna's axis; neglect the Earth and stars.) 3.5 The spectral, hemispherical emittance of a (hypothetical) metal may be approximated by the relation- ship

Answer 1

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