Heat Transfer: Radiation, Dielectric and Ohmic

As we learned in the previous chapters, in conventional thermal processes, heat is generated outside of the object to be heated and is then transferred to the material by conduction, convection, or a combination of the two mechanisms. Radiation is the third mode of energy transfer that occurs through electromagnetic waves without involving a medium. Light and heat are examples of types of radiations. In process engineering applications, all three modes of heat transfer are generally involved. Thermal processing technologies using specific radiation waves and Ohmic heating, where thermal energy is generated and absorbed directly by food materials, are finding increasingly new applications for targeted energy delivery to improve food product quality and achieve higher energy efficiencies.