The basic structure of freeze dryers mainly includes the following parts: refrigeration system, vacuum system, heating system and control system.
Refrigeration system
The refrigeration system is the core component of the freeze dryer. Its main function is to quickly freeze the sample to a low temperature state, freeze and crystallize the water, and provide the necessary conditions for the subsequent sublimation process. The refrigeration system usually includes a compressor, a refrigerant, an oil separator, a water condenser, a drying filter, an intercooler, a sight glass, a solenoid valve, a hand valve, an expansion valve, an evaporator (plate exchanger, rear box condensing coil), a vapor-liquid separator, a return air filter, a pressure gauge, a pressure control relay, a safety valve and a refrigeration pipeline, etc.
Vacuum system
The vacuum system is used to create and maintain the low-pressure environment required in the freeze-drying process to promote the sublimation process of water. The vacuum system mainly includes a vacuum pump (such as a rotary vacuum pump and a turbomolecular pump), a vacuum sensor and a control valve, etc., which are used to monitor and adjust the vacuum degree to ensure the stability and controllability of the vacuum degree throughout the freeze-drying process.
Heating system
The heating system is mainly used to provide the necessary heat during the freeze-drying process to accelerate the process of water sublimation. The heating system can be heated by direct electric heating or by using an intermediate medium such as circulating fluid or silicone oil. The heating plate or heating pad is installed under the freezing plate to promote the sublimation process of ice by conducting heat.
Control system
The control system is the intelligent core of the entire equipment, which is used to monitor and control the operating status of the freezing, vacuum and heating systems to ensure precise control and stable operation of the entire process. The control system includes a temperature controller and a pressure controller to monitor and control the temperature of the freezing plate and the heating plate and the pressure of the vacuum system.
