Low-temperature nitrogen equipment, such as liquid nitrogen freezers, mainly uses the evaporative endothermic effect of liquid nitrogen to achieve its refrigeration function. Here’s a detailed explanation of how it works:
Storage & Transportation
First, liquid nitrogen is stored in liquid nitrogen storage tanks. When refrigeration is required, liquid nitrogen is introduced into the cooling unit via a pressure controller and a conveyor pipe.
Evaporative endothermy:
When liquid nitrogen comes into contact with the surrounding air, it evaporates rapidly. This evaporation process requires the absorption of a large amount of heat, which causes the temperature of the surrounding air and the object to be cooled to decrease rapidly.
Cooling cycle: The cooled object in the cooler is further reduced by heat exchange with low-temperature nitrogen. This process is constantly cycled to keep the cooled object at a low temperature.
For more complex cryogenic nitrogen equipment, such as liquid nitrogen chillers, the working principle consists of the following main steps:
Compression
Nitrogen compressors compress low-pressure nitrogen into high-pressure gas.
Condensation
The high-pressure gas enters the condenser, and through the action of the cooling medium, the high-pressure gas cools and converts into a liquid state.
Expansion
Liquid nitrogen passes through the expansion valve, controlling its pressure and flow, thereby expanding into nitrogen at low temperature and low pressure.
Evaporation
In the evaporator, the low-temperature and low-pressure nitrogen evaporates again and absorbs the heat of the surrounding environment, thus achieving the refrigeration effect.
These steps are constantly cycled to maintain the low temperature state of the equipment, allowing it to be used in many fields, such as food freezing, medical cryopreservation, scientific research, etc.
In summary, the low-temperature nitrogen equipment achieves an efficient refrigeration effect by using the evaporative endothermic effect of liquid nitrogen, combined with the steps of compression, condensation, expansion and evaporation.
