Radiation to a Tube from a Large Enclosure. A small oxidized horizontal metal tube $472K(390F)$ is in a very large furnace enclosure with firebrick walls and the surrounding air at $1088K(1500F).$ The emissivity of the metal tube is $0\mathrm{.}94$ at $1088K$ and $0\mathrm{.}79$ at $472K.$ Calculate the heat transfer to the tube by radiation using SI and English units.