Frystorkningsprincip för vakuumfrysningstork
Freeze-drying principle of vacuum freeze dryer: The freeze-drying process is also the sublimation process of liquid water. Water has three aggregation states, namely the liquid state, solid-state, and vapor state. Based on the three-phase equilibrium theory of water, it can be known that the temperature of the triple point of water (the coexistence of vapor, liquid, and solid) is 0.0098℃, and the pressure of the triple point is 609.3Pa. Vacuum freeze-drying is carried out below the triple point. Freeze-drying is to use the principle that when the pressure is lower than the triple point pressure, the ice crystals absorb heat and directly convert it into vaporous water ånga för att frysa färska material vid låg temperatur i vakuumfrittorkningsmaskinen. Under det höga vakuumtillståndet, med användning av sublimeringsegenskaperna för vatten, kan vattnet i materialet direkt sublimeras till vattenånga i isstaten utan att smälta is, så att materialet kan frystorkas.
During vacuum freeze-drying, the temperature of the heating plate, the temperature of the material, the temperature of the condenser, and the vacuum℃of the drying chamber all change with time, and any one or several links may become the "bottleneck" of the drying process. In order to ensure the feasibility of the freeze-drying process and process qualified freeze-dried products, during the freeze-drying process, the temperature of the produkt och plattan, kondensorns temperatur och vakuumgraden dras in i en kurva, som kallas en frystorkningskurva . När olika frystorkningskurvor används för samma produkt, är kvaliteten på produkten också annorlunda; different products, different vacuum freeze-dryers and the characteristics of the frozen material, and different operating conditions also apply different freeze-drying curves. Even if a qualified product is obtained, the data should be analyzed to provide a basis for further optimization. Selecting an appropriate freeze-drying profile is the key to the freeze-drying process.
