A short, one-side closed cylindrical tube is used as a surface-radiation source, as shown in Figure Pr. 4.17. The surface (including the cylindrical tube and the circular closed end) is ideally insulated on its outside surface and is uniformly heated by Joule energy conversion, resulting in a uniform inner surface temperature T1 = 800?C. The heat transfer from the internal surface to the surroundings is by surface-radiation only
