Ultra low temperature chiller - cascade freezer - low temperature deep water chiller

The screw type cascade low-temperature unit uses a screw compressor as the refrigeration power source for the low-temperature stage, with a cooling water tower as the condensing medium. The unit is designed as an integrated unit for easy installation and maintenance. The output horsepower of the unit ranges from 40HP to 160HP, and the low-temperature liquid outlet temperature control range is -45 ℃ to -120 ℃ The screw cascade low-temperature unit can provide low-temperature refrigerant ranging from -120 ℃ to 0 ℃. It has been widely used in industries such as pharmaceuticals, electronics, tires, beverages, wires, vacuum coating, injection molding, textiles, natural gas, laser equipment, welding equipment, medical equipment, etc.

Advantages of ultra-low temperature cascade refrigeration unit (cascade refrigeration unit) compared to liquid nitrogen:
1. The cost of using liquid nitrogen is 7-10 times that of using ultra-low temperature cascade refrigeration units; The vaporization heat of liquid nitrogen is 5.6KJ/mol=200kJ, the refrigeration power is 1kw. h, and 18KG=22 liters of liquid nitrogen are required.
2. Low temperature refrigeration units can accurately control temperature, while liquid nitrogen temperature control is more difficult;
3. The transportation and storage of liquid nitrogen are very complicated, and once interrupted, production will stop;
4. The use of liquid nitrogen carries certain risks and requires a license for use.
Application of refrigerant:
When the ultra-low temperature cascade refrigeration unit (cascade refrigeration unit) is applied in industries such as pharmaceuticals, chemicals, and aerospace heat sink experiments, a refrigerant circulation system is usually required between the ultra-low temperature freezer (cascade refrigeration unit) and the user's load reaction tank. The main reasons are:
1. The load volume of general users is relatively large. If the load requires uniform temperature, it must be filled with refrigerant. However, at room temperature, a large amount of low-temperature refrigerant will turn into gas, and the volume and pressure of the gas will be huge, which the equipment itself will not be able to meet;
2. The load on the user's site is far away from the refrigeration room, and the load area is usually a clean, explosion-proof, and quiet area. The refrigerant circulation system can separate the cryogenic unit and the load area, making the entire system safer and more reliable;
3. Usually, the cooling capacity is achieved by cooling the materials inside the load through the heat exchange coils. Once the heat exchange coils leak, it may contaminate the materials. The refrigerant system usually uses substances that are in contact with the material solvent, so even if there is a leak, the possibility of contamination can be completely avoided;
4. Refrigerant is also a carrier for storing cold energy, which can be adjusted by refrigerant when the load changes significantly. This is beneficial for temperature control and energy conservation. Generally speaking, the greater the load fluctuation, the more refrigerant is required.
5. The heat exchange efficiency is higher than that of liquid nitrogen. Liquid nitrogen uses latent heat of evaporation to release cooling energy. After absorbing heat, liquid nitrogen becomes gaseous, and a mixture of vapor and liquid phases occurs inside the coil, resulting in significant gas resistance and a sharp decrease in flow rate. This prevents liquid nitrogen from fully contacting the tube wall, greatly reducing heat transfer efficiency.
Refrigerants generally use glacier refrigerants (freezing point -118 ℃), dichloromethane (boiling point 40 ℃, freezing point -95 ℃), alcohol (boiling point 78 ℃, freezing point -114 ℃), dichlorofluoroethane (boiling point 32 ℃, freezing point -103 ℃), trifluorodichloroethane (boiling point 28.7 ℃, freezing point -107 ℃), difluorochloroethane (boiling point -10 ℃, freezing point -131 ℃), which are non-toxic, non flammable, environmentally friendly, and inexpensive. The circulation of refrigerant adopts a magnetic circulation pump to reduce pollution and the impact of low temperature on bearing sealing.