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Although modern drying equipment and drying technology have a history of more than 100 years, they still belong to the category of experimental science. Most drying technologies currently lack scientific theories and design methods that can accurately guide practice. Therefore, before the construction of large-scale drying equipment, sufficient and convincing experiments must be carried out, and the experimental results shall be used as the basis for the design of the drying equipment. This is a significant feature of the drying equipment design. In practical applications, relying on experience and small-scale experimental data is the main way to guide the design of drying equipment.

First, some basic disciplines on which the drying equipment depends (mainly disciplines under the category of transmission engineering) have the characteristics of experimental science. For example, the research and development of aerodynamics must be promoted by "wind tunnel" experiments, which means that it has not deviated from the scope of experimental science, and the development level of these basic disciplines directly affects and determines the development level of drying technology.

Second, the drying process of many dryers is a process where multiple disciplines and technologies are converged, involving a wide range of areas, many changing factors, and complex mechanisms. For example, in the field of spray drying technology, the trajectory of the atomized droplets in the drying tower is the key to engineering design. The trajectory of the droplet is related to its volume, mass, initial speed and direction, and the flow direction and velocity of other droplets and hot air around it. However, these parameters are changing all the time due to the progress of mass transfer and heat transfer, and in the initial state, neither the size of the droplets nor the distribution of hot air can be uniform. Obviously, it is unreliable to only rely on theoretical calculations for engineering design for such a complex and changeable process.

Third, the types of materials to be dried are varied, and their physical and chemical properties are also different. Even under the drying conditions of the same dryer, the mass and heat transfer rates of different materials may be quite different. If they are not treated differently, they may cause unsatisfactory consequences. For example, although the drying of some Chinese herbal medicines belongs to the same kind of medicinal materials, the drying conditions must be changed only because of the differences in the origin or harvest period of the medicinal materials, otherwise the product quality will be affected.

These three reasons determine that the development and application of drying equipment should be based on experiments. However, these characteristics of drying equipment are often overlooked intentionally or unintentionally. Manufacturers often avoid drying experiments that should be done due to lack of experimental equipment or incomplete models (this is a common phenomenon in our country), and users often give up necessary experiments because they don’t understand the characteristics of drying equipment. Requirements. The result is that the drying equipment is not used well, and even the design of the scheme fails.