Chapter 12, Problem 12.44P

Estimate the total, hemispherical emissivity $\epsilon$ for polished stainless steel at 800 K using Equation 12.43 along with information provided in Figure 12.17. Assume that the hemispherical emissivity is equal to the normal emissivity. Perform the integration using a band calculation, by splitting the integral into five bands, each of which contains 20% of the blackbody emission at 800 K. For each band, assume the average emissivity is that associated with the median wavelength within the band ${\lambda }_m$ , for which half of the blackbody radiation within the band is above ${\lambda }_m$ (and half is below ${\lambda }_m$ ). For example, the first band runs from $\lambda =0to{\lambda }_1$ , such that $F_{(0\to \lambda 1)}=0.2$ , and the median wavelength for the first band is chosen such that $F_{(0\to \lambda m)}=0.1$ . Also determine the surface emissive power.