16. Cooling of Steel Spherical Balls by Natural Convection and Radiation Heat Transfer in Unsteady State

In this chapter, steel spherical balls at different radii that were heated to 400 C (673 K) by infrared radiation in a vacuum environment in Chapter 15 will be cooled down slowly by natural convection and by infrared radiation heat transfer in unsteady state down to a temperature of 50 C (323 K). A hot spherical ball will be placed at the center of a large air chamber in which chamber air and chamber walls are kept at a constant temperature at 25 C (298 K). This kind of slow cooling down of hot metals are done in order to relieve stresses that are generated in the metal structures during their processing.