The working principle of freeze dryer is based on the three states of water, namely solid, liquid and gas. The freeze dryer first freezes the material to be dried to below the triple point temperature (usually -40℃ to -50℃), and then sublimates the solid water in the material directly into water vapor under vacuum conditions to remove the water.
Specific steps
Material freezing: Put the material to be dried into the material box of the freeze dryer for freezing, so that its temperature drops below the freezing point, fixes the water in the material, and prevents the flow and loss of liquid water in the subsequent process.
Vacuum dehumidification: Start the vacuum system to vacuum the material box to put the material in a low vacuum state. Under vacuum conditions, the water in the material sublimates directly from solid to gas.
Heating and drying: In order to accelerate the sublimation process of water and ensure that the material temperature is not too high, the heating system will heat the material appropriately. The heating system usually uses heat transfer oil or other heat media to transfer heat to the material evenly through heat conduction.
Collecting moisture: The sublimated water vapor enters the cold trap (water trap) through a vacuum pipe, where it condenses into ice crystals when it encounters cold, thereby achieving the collection of moisture.
