In fact, freeze-drying has many different uses, especially in many biochemical and pharmaceutical applications. It can be used to obtain a longer shelf life.
In addition, it can retain its inherent Biological activity and structure. To this end, vacuum lyophilizers can also be used to prepare tissue preparations for structural studies. When the vacuum freeze dryer is in use, what factors will affect the speed of the vacuum freeze dryer?
1. Monotonic indoor pressure
The internal pressure of the monotonic chamber will directly affect the heat and mass transfer rates. The lower the pressure, the better the mass transfer. The higher the pressure, the better the heat transfer will be.
2. Heat transfer method
General heat transfer methods include convection, conduction, heat radiation, and medium heating. However, the transfer between heat and mass is involved in the freeze-drying process, so which conduction method to choose can transfer heat to the material faster, which has a great influence on the monotonic rate of the item.
3. How much is loaded
When lyophilizing materials, there will be a certain ratio of surface area to material thickness after being sub-packed into containers, that is, freeze-drying is related to loading.
The small surface area and thickness are conducive to the evaporation of water, and the freeze-drying is simple and of higher quality. In the case of monotony, the monotonous wet weight loading on the tray per unit area is an important factor in selecting the monotonous time.
Under normal circumstances, the thinner the thickness of the material stack, the faster the heat and mass transfer will be, and the monotonous time will be faster. also shorter.
However, if the material thickness is thin, there will be less monotonous material per batch per unit freeze-drying area, which will affect the freeze-drying area and unit time output of the freeze-drying unit.
4. Pre-freezing rate
During the freezing process of the material, the formed crystals will affect the monotonic rate and the monotonic dissolution rate.
The process of quick freezing and slow freezing has the following differences: the ice crystals produced by quick freezing are relatively small, and the ice crystals produced by slow freezing are relatively large.
Large ice crystals are more conducive to evaporation, but small ice crystals are more difficult to evaporate. Rapid freezing leads to low drying rate and fast desorption rate; slow freezing leads to fast drying rate and slow desorption rate.
5. Shape and composition of materials
Generally, freeze-dried materials are solid and liquid, and the shape and concentration of the two have a very large influence on the monotonic rate of the freeze-drying machine.
To sum up, the monotonous indoor pressure, heat transfer method, loading volume, pre-freezing rate, and the shape and composition of the material will all affect the freeze-drying rate of the vacuum freeze-drying machine!