In this device, the drying of materials is based on the production of heat for the evaporation of water and the transfer of the evaporated water from the inside of the dryer by the operating fluid . In cases where materials are sensitive to heat, the design of the dryer can be based on mass transfer, which is accompanied by creating negative pressure inside the device.
Dryers are usually designed based on the input and output humidity, as well as the capacity and size of the input materials and the sensitivity of the materials to heat.