What is freeze dryer?

Freeze dryer is the abbreviation of vacuum freeze dryer. Freeze-drying is a drying technique using the principle of sublimation. This is a new type of vacuum freeze dryer equipment integrating heat, vacuum, refrigeration, pressure vessel manufacturing and automatic control technology.

freeze dryer
freeze dryer

What are the main system components of the freeze dryer?

The freeze dryer is mainly composed of four main parts: vacuum system, refrigeration system, circulation system (heating system) and control system.
1.The vacuum system consists of a vacuum meter, a vacuum pump, a freeze-drying chamber, a condenser, etc. It mainly vacuumizes the freeze-drying chamber and cold trap.
2.The refrigeration system consists of a freezer and pipes inside the freeze-drying chamber. It mainly refrigerates the freeze-drying chamber and the condenser.
3. The circulation system (heating system) consists of a series of cooling and heating heat exchangers, etc., which mainly provide cold and heat sources for the shelves.
4. The control system is composed of electrical control components, etc., which mainly control the operation and process setting of the freeze dryer.


1.In the pharmaceutical industry. Freeze-drying technology is mainly used for the production of blood products and vaccines. And the preservation of antibiotics, vaccines and other products.
2.In the biological industry, freeze-drying technology is mainly used for biological materials that require long-term preservation. Such as microbial culture, blood, enzymes, nerve tissue and various organs.
3.In the chemical industry, freeze-drying technology is mainly used for dry samples or concentrated samples to increase the sensitivity of the analysis. Freeze-drying stabilizes the sample composition without changing the chemical composition.
4.In the food industry, freeze-drying technology is mainly used for fruits, vegetables, poultry, aquatic products, condiments, etc.

working principle

The working principle of the freeze dryer is to use the method of freezing and vacuuming. First, the material is quickly frozen at low temperature, and then in a suitable vacuum environment, the frozen water molecules are sublimated into water vapor.

home freeze dryer
home freeze dryer

What are the phases of freeze drying?

Freeze-drying is a process of gradually warming up from a low temperature. If the temperature rises too fast or the temperature is too high, the shape and taste of the freeze-dried product will easily be bad.
The freeze-drying phase is divided into: pre-freezing, sublimation drying , and Secondary Drying (Adsorption) .
1. Pre-freezing
Pre-freezing needs to set the temperature, time and rate according to the nature of the material. The pre-freezing process directly affects the quality of the material.
2.Drying phase
The first phase is sublimation. The frozen material is heated in a vacuum chamber, and the ice crystals are sublimated into water vapor to dehydrate and dry the product.
The second phase is adsorption. After the first phase, there is still about 10% of the water adsorbed in the material, which provides conditions for the reproduction of microorganisms. We need to remove moisture to improve product storage stability and extend shelf life.
Since freeze-dried products are generally porous and loose, they are prone to moisture and breakage. For better preservation, be sure to use vacuum packaging or inert gas for packaging.

Precautions when using the freeze dryer

1.The vacuum pump is placed flat on the ground and maintains a certain height difference with the freeze dryer.
2.Before lyophilizing the material, you need to turn on the power and cool it for half an hour.
3.First of all, the material should be pre-frozen. The lyophilization process can only be started when it has been pre-frozen in a solid state (frozen state).
4.Maintenance of vacuum pump oil. Too little oil will result in insufficient vacuum, and too much oil will result in oil spills.
5. After the material is freeze-dried, first turn on the inflation valve to allow the air to enter slowly. Then turn off the vacuum pump to prevent the backflow of the vacuum pump oil. Finally turn off the vacuum gauge, cool button and main power.
6. Regularly clean the cold trap chamber and freeze-drying chamber.

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