The low-temperature sublimation technology of freeze-drying machine is the process of freezing substances and directly sublimating ice into water vapor under vacuum conditions. The main working principle of this technology can be divided into three stages: pre freezing, sublimation drying, and analytical drying. This technological process can remove moisture, extend shelf life, and preserve the form and nutritional components of substances without damaging them. The following is the detailed working principle of the low-temperature sublimation technology of the freeze dryer:

1. Pre freezing stage

In low-temperature sublimation technology, the substance is first rapidly frozen. The specific process is as follows:

Freezing: Quickly cool the substance to a lower temperature (usually between -30 ° C and -50 ° C). Within this temperature range, the moisture in the substance freezes, causing it to enter a solid state. This process requires a high freezing speed for the substance, and rapid freezing helps to form smaller ice crystals and avoid damage to the material structure.

Function: The main function of the freezing process is to convert the moisture in the substance into solid ice, preparing for subsequent sublimation drying. Rapid freezing can maintain the cellular structure and morphology of substances.

2. Sublimation drying stage (preliminary drying)

This stage is the core of freeze-drying machine technology, involving the direct conversion of ice from solid to gaseous state, bypassing the process of liquid state, which is known as sublimation phenomenon. Its working principle is as follows:

Vacuum environment: During the sublimation drying stage, the freeze-drying machine reduces the pressure inside the drying chamber to a low state through a vacuum pump. Under vacuum conditions, ice can sublime directly from a solid state to a gaseous state at lower temperatures.

Heating sublimation: While maintaining a vacuum, the freeze-drying machine will moderately heat the frozen substance. The main purpose of heating is to provide the energy required for sublimation, allowing ice to transform from a solid state to water vapor. This process is called sublimation, during which approximately 90% -95% of the moisture is removed.

Sublimation mechanism: Due to being in a vacuum state, the water inside the substance does not undergo a liquid state transformation, but directly transforms from solid ice to water vapor. The vacuum environment increases the pressure difference between the surface and interior of the material, promoting smoother sublimation of ice.

3. Analyze the drying stage (secondary drying)

After sublimation drying, there will still be a portion of adsorbed moisture in the material, which is difficult to remove through sublimation. The working principle of drying analysis is as follows:

Further heating: During the desorption drying stage, freeze-drying will further increase the temperature of the substance, usually heating it to a higher temperature (such as 20 ° C to 40 ° C), which helps to desorb the remaining adsorbed moisture.

Continue vacuuming: Maintain a vacuum environment and reduce the moisture content to di level (generally below 1% -3%) by evaporating the remaining adsorbed water.

Final drying process: This process reduces the moisture content of the substance to an extremely low level, allowing it to be preserved for a long time and maintain its original form and quality.

Freeze drying technology utilizes the physical properties of water. Water exists in three forms: solid ice, liquid water, and gaseous water vapor at specific temperatures and pressures. Under atmospheric pressure, water typically melts from a solid state (ice) to a liquid state, and then evaporates into a gaseous state. However, in a vacuum environment, water can directly rise from solid ice to gaseous water vapor. This is the basis for freeze-drying technology to avoid damage to substances caused by liquid water.

summary

The low-temperature sublimation technology of freeze-drying machine is a drying technology that utilizes vacuum environment and temperature control. By freezing the moisture in the substance and directly sublimating it into a gaseous state, the damage of high temperature to the substance during traditional drying process is avoided. Low temperature sublimation technology is widely used in fields such as food, pharmaceuticals, and biological research. Its core principle allows substances to retain their structure, nutritional components, and activity after drying.