Working Principle of Screw Chiller

The working principle of the screw chiller is based on the steam compression refrigeration cycle, and refrigeration is mainly achieved through four processes: compression, condensation, throttling, and evaporation. The following is a detailed introduction:

 

Screw chiller

 

1. Compression process:

 

The refrigerant vapor in the evaporator is sucked into the screw compressor. The screw compressor is an important component of the chiller. The motor drives the rotor of the compressor to rotate, so that the yin and yang rotors mesh with each other. When the rotor rotates, the volume between the teeth changes continuously, which compresses the refrigerant vapor and increases its pressure.

 

As the compression proceeds, the temperature of the refrigerant vapor also increases accordingly. The compressed high-temperature and high-pressure refrigerant vapor is discharged from the compressor and is ready to enter the condenser.

 

2. Condensation process:

 

The high-temperature and high-pressure refrigerant vapor discharged from the compressor enters the condenser. There is usually circulating cooling water in the condenser, and the cooling water continuously flows through the pipes of the condenser.

 

The high-temperature and high-pressure refrigerant vapor exchanges heat with the cooling water in the condenser and transfers heat to the cooling water. The temperature of the refrigerant vapor gradually decreases. When the temperature drops to the corresponding saturation temperature, the refrigerant vapor begins to condense into liquid.

 

During the condensation process, the cooling water absorbs the heat of the refrigerant vapor and the temperature will rise. After heat exchange, the refrigerant becomes a high-pressure liquid and remains at the bottom of the condenser.

 

3. Throttling process:

 

The high-temperature and high-pressure refrigerant liquid at the bottom of the condenser passes through a throttling device, such as a thermal expansion valve or an electronic expansion valve. The function of the throttling device is to reduce the pressure of the refrigerant liquid, and during the pressure reduction process, the temperature of the refrigerant liquid will also decrease.

  

After throttling, the refrigerant becomes a low-pressure, low-temperature gas-liquid mixture and enters the evaporator.

 

4. Evaporation process:

 

The low-pressure, low-temperature refrigerant gas-liquid mixture enters the evaporator. The pressure in the evaporator is low, and the refrigerant liquid is easy to evaporate in this low-pressure environment.

 

When the refrigerant evaporates in the evaporator, it absorbs heat from the refrigerant (such as chilled water), which reduces the temperature of the refrigerant. The refrigerant circulates in the evaporator, continuously transferring heat to the refrigerant, and its own temperature continues to decrease.

 

After evaporation, the refrigerant turns into gas, and the gaseous refrigerant is sucked back into the compressor to start the next cycle.

 

During the entire working process, the screw chiller continuously repeats the above four processes of compression, condensation, throttling, and evaporation to achieve a continuous cooling effect. At the same time, in order to ensure the normal operation of the unit and the lubrication of the compressor, an oil circulation system is also provided. When the compressor is running, the refrigerant oil will be discharged from the compressor along with the refrigerant gas, and the refrigerant oil will be separated by the oil separator and sent back to the compressor to ensure the normal lubrication and operation of the compressor.