The spectral emissivity for a material is shown in Figure P15.16 and does not depend much on the temperature.

a. What is the total hemispherical absorptivity for the material if it is exposed to radiation from a blackbody source at \(1500 \mathrm{~K}\) ?

b. What is the total hemispherical absorptivity if the material is exposed to radiation from a graybody source at \(1550 \mathrm{~K}\) with an emissivity, \(\varepsilon^{r}=0.75\) ?

c. What is the total hemispherical absorptivity if the material is exposed to radiation from an identical material acting as the source at \(1500 \mathrm{~K}\) ?

Transcribed Image Text:

FIGURE P15.16 0.6 E(A) 0.4 0.2- 2 4 (m)