Conveyor and cabinet drying of materials using a functional ceramic

Abstract

The current problem of conveyor and cabinet drying of various materials is considered. Radiation infrared drying using nonlinear infrared radiation (IR) transducers based on a functional ceramic is studied.Use of IR of a special spectral composition and structure makes it possible to shorten processing duration considerably, to improve product quality, to simplify the design layout, and also to create conditions for mechanizing and automating production.Recently in various branches of industry there has been development of materials heat treatment using infrared (IR) radiators. As a result of using IR in many production processes (drying, baking, roasting, polymerization, disinfection, pasteurization, etc.) [1, 2], processing duration is considerably shortened, product quality is improved, the design layout of units is simplified, and mechanization and automation are possible.The main advantages of IR radiation and production processes based upon it is provision of a marked increase in the density of heat flow at the surface of the material being irradiated and penetration of the IR beam into the material.In drying many materials, especially capillary-porous materials, IR beams falling on the surface penetrate into the material, and in areas of meniscuses (in pores and capillaries) beams are absorbed by them similar to a black body, and therefore in the initial instant the temperature within the depth of a solid skeleton is greater than at its free surface. As a result of this, a temperature gradient arises, "coinciding" with the moisture gradient that forms due to the fact that evaporation of moisture does not occur from the whole geometric surface of liquid meniscuses that during drying move into the material (there is drawing of moisture from pores through neighboring channels). After some time, the temperature of the solid skeleton surface starts to exceed the temperature within the depth of the material being dried, i.e., there is a change in the direction of the temperature gradient and there is a reduction in moisture evaporation with an increase in material temperature due to the continuous input of electric energy to the IR heater system. Therefore for capillary-porous materials, with the aim of maintain-