1、 Centrifugal compressor
The centrifugal compressor is located above the chiller and has a large volute shaped pipe curled into the condenser. The refrigerant flows in through the suction pipe and hits the center of the impeller. The blade rotates and applies the angular velocity to the refrigerant. This angular velocity makes the refrigerant fly out at high speed in all directions and gather in the volute (outer ring), increase the pressure by kinetic energy conversion, and then enter the condenser downward. This type of compressor / cooler is a common device of centralized machine room in large buildings.
2、 Screw compressor
Screw compressor chiller
Screw compressors are used for water-cooled and air-cooled chillers. The water-cooled compressor is located at the top of the chiller and the air-cooled compressor is located below the chiller. Indoor water-cooled chillers are usually insulated, while air-cooled chillers may not. The refrigerant enters the gap between the two screws from the evaporator, but as the screws rotate, they push the refrigerant further into the compressor and squeeze it. The refrigerant will flow out under high pressure and high temperature to the expansion valve.
Air cooled chiller screw compressor
The above is a picture of an air-cooled chiller with two screw compressors. 1-2 small screw compressors are common on air-cooled chillers. They can work in parallel, and some designs allow grading by turning off one of the compressors.
3、 Scroll compressor
Scroll compressor chiller
Scroll compressor is mainly used for air-cooled chillers, but it can also be seen on water-cooled chillers. Usually, one compressor is not enough to meet the cooling load, so several compressors are combined. In the picture above, the blue cylinders below the cooler are compressors, which are connected together to form a group.
For this type of compressor, the refrigerant usually enters through the bottom and is sent to the moving scroll plate. One disc is fixed and the other disc rotates to compress the refrigerant into a more compact space. When the disc moves, the refrigerant is forced to rotate and compress around the spiral, and then it will leave through the top and flow to the expansion valve.
4、 Reciprocating compressor
Reciprocating compressor chiller
Reciprocating compressors are becoming less common as newer and more efficient technologies replace them, so these types are slowly being phased out in commercial refrigeration. But it is still very popular in the field of industrial refrigeration. The reciprocating compressor has reliable quality, convenient processing, low material requirements and low cost. It can run for a long time as it is properly maintained. However, there are many moving parts, complex structure, heavy maintenance workload and high maintenance cost.
In reciprocating compressors, the refrigerant is compressed by driving the piston in the cylinder to move back and forth.