During drying, heat is applied to the product to evaporate water or organic solvent. The drying temperature and its duration depend on the thermolabile nature of the product, the hydrodynamic regime, the product quality requirements and the desired residual moisture content. Since the product cools as the solvent evaporates, in some cases drying can be carried out at relatively high temperatures without overheating the product.
In this case, it is important to ensure intensive heat and mass transfer in the drying process by mixing, carrying out the process in an active hydrodynamic regime, creating a large contact surface of phases. During the thermal drying process, shrinkage of the material is possible, and in case of non-equilibrium heat and mass transfer, the formation of bubbles inside the material or its rupture is possible. The drying process can also be used to impart the necessary properties to the dried products, to obtain dispersed products with a given structure and shape of particles. When drying materials it is necessary to correctly select the method of drying. The choice of a rational drying mode and method of drying can be determined by the properties of a particular material to be dried, the conditions and objectives of this production.

When drying powders and granular materials, it is required that the preparation has good bulkiness, does not stick, and has a certain dispersibility. Traceability of powders worsens their technological properties: powders do not lend themselves well to automatic dosing, require additional processing, such as the addition of auxiliary substances. For example, good flowability can be achieved by using a spray dryer. A properly organized drying process can preserve or improve the properties of materials. For example, drying tablet granulate in contact dryers leads to sintering, discoloration, uneven residual moisture content, deterioration of bulkiness, and decomposition of active ingredients. Fluidized bed and spray drying reduces most of these drawbacks. Freeze drying is widely used for drying biologically active drugs, which may lose their biological activity during heat drying. This method of drying requires the investment of large financial and time costs, so it is advisable to use it only in the production of expensive drugs. Today it is especially important to create new drying methods and appropriate equipment for processing thermosensitive materials with the possibility of obtaining a product with specified properties.