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The principle of a freeze dryer, what is a vacuum freeze dryer?
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- Time of issue:2020-12-05 22:04
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(Summary description)First of all, let's understand vaporization and sublimation. The process of a substance changing from a liquid phase to a gas phase is called vaporization. For water, if the ambient temperature is gre
The principle of a freeze dryer, what is a vacuum freeze dryer?
(Summary description)First of all, let's understand vaporization and sublimation. The process of a substance changing from a liquid phase to a gas phase is called vaporization. For water, if the ambient temperature is gre
- Categories:Industry Information
- Author:
- Origin:
- Time of issue:2020-12-05 22:04
- Views:
Information
First of all, let's understand vaporization and sublimation. The process of a substance changing from a liquid phase to a gas phase is called vaporization. For water, if the ambient temperature is greater than 0 degrees and the partial pressure of water vapor is less than the saturated vapor pressure of water, vaporization can proceed smoothly. Most of the current drying methods work according to this principle. The process of changing a substance from a solid phase to a gas phase is called sublimation. If the ambient temperature is less than 0 degrees, the water exists in the form of solid ice, and the partial pressure of water vapor in the environment is less than the saturated vapor pressure of the water on the surface of the ice, then the sublimation can proceed smoothly. At this time, the partial pressure of water vapor in the environment is greater than the saturated vapor pressure of water on the ice surface, and the water vapor condenses into ice or frost. We call this sublimation, which is the opposite process of sublimation.
What is the freeze-drying phenomenon? It is a common concept that after washing the clothes, the clothes should be dried in a higher temperature, ventilated and dry environment. The higher the ambient temperature and the higher the air dryness, the faster the clothes will dry. But in severe cold areas, people find that washed clothes are cold in the back sun, which is always ice and snow, and clothes that are frozen into a hard state will also dry. In addition, people have also found that the unpackaged food in the freezer and the freezer compartment of the refrigerator has been frozen hard, but the surface has been dried. These are freeze-drying phenomena.
Next, let's understand the principle of freeze-drying. As we said earlier, when the temperature is 0 degrees, the water is just above the freezing point. At this time, the water is in the three states of liquid, gas and solid. We call this the three-phase point of water. When the temperature rises, water appears in two phases of vapor and liquid; when temperature rises, water appears in the form of two phases of vapor and solid. When the water freezes into ice, we know from the previous study that as long as the partial pressure of water vapor in the environment is less than the saturated vapor pressure of the ice at the corresponding temperature, the ice will directly change from solid to vapor for the drying process. We take this process It is called sublimation drying, and the phenomenon of ice directly changing from a solid state to a gas state is called sublimation. We dry the materials while they are frozen. During the drying process, the ice does not melt, and the process of directly vaporizing and drying the ice from the solid state is called freeze-drying (freeze-drying for short).
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