ABSTRACT
In heat treatment of most agricultural materials, whether heating or cooling, heat transfer is rarely to a single solid particle, but the single particle situation is a starting point for describing the multiparticle condition. If the particle does not move relative to its engulfing fluid, heat transfer between the solid and the fluid is by conduction, or, if the fluid is transparent, by conduction and radiation. When there is relative motion between the fluid and the solid, heat transfer by convection is also added. Figure 5.1 shows the paths of heat transfer in a mass or multiparticles of a material involving heat exchange 1) through the solids, 2) solid to solid through the contact surface, 3) radiation between solid surfaces, 4) and 5) radiation within the voids and solid to void, and 6) the gas film near points of contact between the solids.
