Firstly, the low-temperature freezing stage utilizes the heat absorbed by the refrigerant during evaporation to lower the temperature of the cooled object until it drops below minus 78 ° C, reaching below freezing point and causing water to form ice. This process can maximize the preservation of the original form, color, taste, nutritional components, and activity of the substance.

The next stage is sublimation drying. During the sublimation drying process, solid ice crystals will directly convert into gaseous water vapor. This process is carried out in a high vacuum environment because the binding force of water molecules in solid ice crystals is weak. Therefore, under vacuum conditions, the water in the ice crystals can quickly sublime into water vapor. At the same time, the heating system will heat the substance, providing the energy required for water vapor sublimation and accelerating the escape of water vapor.

Then, the water vapor is condensed into water through an efficient condensation system and discharged. This condensation system usually includes a condenser and a water trap, which can effectively condense water vapor into water and discharge it from the low-temperature freeze dryer.

In addition, the low-temperature freeze dryer is equipped with a vacuum system to maintain a high degree of vacuum during the drying process. The vacuum system creates a low oxygen, low water environment by extracting gases and moisture from materials, which is conducive to the escape of water vapor and the drying of materials.

In short, the working principle of a low-temperature freeze dryer is to achieve efficient and low loss drying of substances through two stages: low-temperature freezing and sublimation drying. This drying method can maximize the retention of nutrients and active ingredients in substances, and is suitable for fields such as food, medicine, and biological products.