What is a cascade cooling system?

Cascade refrigeration is an advanced low-temperature cooling technology. It consists of multiple independent refrigeration circuits connected in series to form a complete cooling system. Each circuit uses refrigerants with different boiling points. The primary system can pre-cool the secondary system to achieve staged cooling. This technology is commonly used in low-temperature chillers and ultra-low-temperature chillers.
 
Perhaps you want to know:
•What is an industrial chiller
•How does a chiller work
•Low-temperature cooling technology

How does a cascade cooling system work?

You may be curious about how the cascade system works. Let’s use a two-stage system as an example to explain in detail. The secondary cascade cooling system is usually composed of a high-temperature circuit, a low-temperature circuit, a control system, and other auxiliary components.
 
The refrigerant used in the high-temperature circuit has a relatively high boiling point, usually between -10℃ and 0℃. The independent compressor of this circuit compresses the high-boiling-point refrigerant, condenses it into a liquid in the condenser, and evaporates and absorbs heat in the evaporator after throttling and reducing the pressure.
 
The evaporator of the high-temperature circuit is also called a cascade heat exchanger. It also acts as a condenser for the low-temperature circuit, which can transfer the cold generated by the evaporation of the high-boiling-point refrigerant to the refrigerant gas of the low-temperature circuit.
 
The low-temperature circuit compresses the low-boiling-point refrigerant and sends the gas to the condenser for condensation. The condenser used here is the evaporator/intermediate heat exchanger of the high-temperature circuit.
 
Subsequently, the refrigerant, which has been throttled and depressurized, evaporates in the low-temperature zone evaporator to provide cooling for the equipment and process.

Advantages of cascade cooling system

Lower temperature

The evaporation temperature of the refrigerant largely determines the minimum operating temperature of the system. If you want the cooling system to reach a lower temperature, you must use a refrigerant that can still boil and absorb heat normally at extremely low temperatures, that is, a low-boiling-point refrigerant. However, this also means that it must reach a lower condensing temperature in the condensation stage.
 
For a single-stage chiller, making the low-boiling-point refrigerant reach the condensing temperature requires a higher compression ratio of the compressor. Why not just use a high-performance compressor then? Because too high a compression ratio will exceed the safety limit of a single-stage compressor.
 
The cascade design can distribute the compression task to two compressors. The high-temperature circuit is responsible for providing a lower condensing temperature for the low-temperature circuit, providing the necessary conditions for the evaporation of the low-boiling-point refrigerant, thereby achieving a lower operating temperature.

Higher stability

Each refrigeration circuit in the cascade chiller operates within the performance range. The high temperature circuit is responsible for reducing the temperature from room temperature to medium temperature, and the low temperature circuit is responsible for reducing the medium temperature to the set temperature. Unlike a single-stage chiller, it will not be in a condition close to the limit pressure for a long time.
 
A more reasonable compression ratio can reduce system failures and extend the service life of the equipment. Moreover, the temperature division of the cascade system is finer, the temperature control is more precise, and the fluctuation of the outlet water temperature is smaller.

Customize your cascade cooling system

If you want the industrial chiller to achieve an operating temperature of -40℃ or below -80℃, you can consider purchasing a cascade chiller using cascade cooling technology. LNEYA provides chillers from -150℃ to +350℃. Within this temperature range, we can customize various performance equipment for you according to your application.
 
Contact us to discuss your cooling needs