ABSTRACT
Drying is a method used to evaporate and remove the liquid, i.e. water, in a wet material. The heat efficiency is important in the drying, because, at least, the latent heat of liquid is needed to remove the liquid. The drying rate is strongly affected by the properties of the material, while the drying rate at the constant drying-rate period is just affected by the operational conditions. During the constant drying rate period, all the heat supplied to the material is used for the evaporation of water. The constant drying-rate period is also observed in the other heat transfers: the conductive and radiation heat transfers. The constant drying rate can be estimated by the heat supplied to the material, but the material temperature is generally different from the wet-bulb temperature in case of other heating methods. To design the dryer, the heat required for the drying of wet material and the dryer capacity should be determined.
