Freezer refrigeration technology principle

March 27, 2019

Drying is one of the ways to keep the material from spoilage. There are many ways to dry, such as drying, boiling, drying, spray drying and vacuum drying. However, these drying methods are all performed at a temperature of 0Â°C or higher. The dried product is generally reduced in size, hardened in texture, and oxidized in some substances. Some of the volatile components are lost. Some heat-sensitive substances, such as proteins and vitamins, denature. Microorganisms lose their vitality. The dried material is not easily dissolved in water. Therefore, there is a big difference in the properties of the dried product compared to that before drying. The freeze-drying method of the refrigerated vehicle is different from the above-mentioned drying method. The drying of the product is basically performed at a temperature of 0Â° C. or less, that is, in the state of freezing the product until the later period, in order to further reduce the residual moisture content of the dried product. Let the product rise to temperatures above 0Â°C, but generally not exceed 40Â°C.

Freeze-drying of a refrigerated vehicle is to contain a large amount of moisture, freeze in advance to form a solid, and then sublimate the water vapor directly under vacuum conditions. The material itself remains in the ice shelf at the time of freezing, so its volume does not change after drying and it is loose and porous. Freezing of ice or other solvents in the product during sublimation absorbs heat. The temperature of the product itself is lowered to slow down the speed of sublimation. In order to increase the speed of sublimation and shorten the drying time, the product must be properly heated. The entire drying is performed at a lower temperature.

Freezer freeze drying has the following advantages:
(1) Freeze-drying of freezers is performed at low temperatures and is therefore particularly suitable for many heat-sensitive materials. If proteins, microorganisms and the like do not degenerate or lose their vitality. Therefore, it has been widely used in medicine.
(2) When the material is dried at low temperature, the loss of some volatile components in the material is small, which is suitable for the drying of some chemical products, drugs and foods.
(3) In the freeze-drying process of a refrigerated vehicle, the growth of microorganisms and the action of enzymes cannot be performed, and thus the original characteristics can be maintained.
(4) Since the drying is performed in a frozen state, the volume is almost unchanged, the original structure is maintained, and the concentration phenomenon does not occur.
(5) The dried material is loose and porous, and it is spongy. It dissolves quickly and completely after adding water, and it almost immediately restores its original properties.
(6) Oxygen is scarce due to drying under vacuum, so some easily oxidized substances are protected.
(7) Drying can eliminate more than 95-99% of water, so that the dried product can be stored for a long time without deterioration.
Therefore, freeze-drying is currently widely used in the pharmaceutical industry, food industry, scientific research and other sectors.

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