Vacuum freeze dryerThrough three stages of pre freezing, sublimation drying, and analytical drying, the principle of sublimation is used to remove moisture from the material. The core process is:

1. Freezing stage: Freeze the materials to be dried (such as solutions, suspensions, solid blocks, etc.) at low temperatures (usually -40 ℃~-10 ℃) to convert the moisture in the materials into solid ice, while avoiding the loss of bioactive substances (such as proteins, microorganisms) in the materials due to high temperature variability or volatile components.

2. Sublimation stage: Place the frozen material in a vacuum environment (usually below 610Pa, which is the triple point pressure of water), and provide a small amount of heat through a heating plate (to avoid material melting), so that ice can sublime directly into water vapor without passing through the liquid state.

3. Analysis of drying stage: After sublimation, there is still a small amount of unfrozen adsorbed water (about 5%~10%) remaining in the material. It is necessary to further increase the vacuum degree and temperature to separate the adsorbed water from the material, and then obtain a dried product with extremely low water content (usually<5%).

Throughout the process, water vapor is captured by a condenser (cold trap) through a vacuum system, forming solid ice and achieving dehydration and drying of the material.

　　Vacuum freeze dryerFreeze the material to form a stable skeleton, retain the porous structure after sublimation, and have good rehydration properties; Vacuum environment isolates oxygen, delays oxidation reaction, and extends shelf life; The required heat source temperature for drying in a frozen state is low, the thermal energy utilization rate is high, and the drying chamber does not require insulation treatment.