ABSTRACT
The theoretical foundations of the crystallization and cooling of layers on a cooled surface are laid down in this chapter. The considerations are applied to the processes occurring on a belt cooler and on a drum flaker. The developed theories apply formaterials crystallizing readily, i.e., the rate of crystallization is determined by the rate of heat transfer. Experimental results confirming the applicability of the theoretical expressions for solidification on cooling belts and drum flakers will be discussed in Chapters 3 and 4. It is assumed that the cooling of the crystallized layers follows the laws of instationary heat transfer. Sec. 2.2 is a short section describing the solidification process. Gregorig’s (1976) approach to describe the crystallization of a layer on a cooled surface is chosen. The model is explained in Sec. 2.3. It is applied to the solidification on a metal wall with a constant temperature in Sec. 2.4. Three different cases are distinguished and the mathematical approaches are relatively simple. Solidification on a metal wall with a variable temperature is attempted in Sec. 2.5. Again, three different cases are distinguished. The mathematical approaches are less simple. However, the definition of four dimensionless numbers is helpful. In Sec. 2.6, the concept of the limiting layer thickness is explained. Finally, the cooling of crystallized layers on a metal wall is discussed in Sec. 2.7.
