Although modern drying technology has a history of more than one hundred years, it still belongs to the category of experimental science. Most drying technologies currently lack scientific theories and design methods that accurately guide practice. In practical applications, relying on empirical and small-scale experimental data to guide industrial design is still the main way, the reasons for this situation are as follows:
One of the reasons is that some basic disciplines relying on drying technology (mainly subject to the discipline of transfer engineering) have the characteristics of experimental science. For example, the development of aerodynamic research is still driven by the “wind tunnel” experiment, which indicates 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.
The second reason is that many drying processes are the process of multi-disciplinary technology convergence, involving a wide range of factors, many changing factors, and complex mechanisms. For example, in the field of spray drying technology, the trajectory of atomized droplets in a drying tower is the key to engineering design. The trajectory of the droplet is related to its volume, mass, initial velocity and direction, and the flow and velocity of other droplets and hot air around it. However, due to the mass transfer and heat transfer processes, these parameters change all the time, and in the initial state, neither the size of the droplets nor the distribution of hot air can be uniform. Obviously, engineering design based on theoretical calculations for such complex and varied processes is not reliable.
Each dryer unit has its own specific application range, and each material can find several drying devices that can meet the basic requirements, but only one type is suitable. If the selection is not appropriate, in addition to the unnecessary one-time high procurement cost, the user has to pay a heavy price throughout the lifetime, such as low efficiency, high energy consumption, high operating cost, poor product quality, and even device fundamentals. Can't run normally and so on.