Analysis of Classification, Differences, Advantages and Disadvantages of Cold Storage Refrigeration Compressors

Introduction to Types of Cold Storage Refrigeration Compressors:
There are many types of cold storage compressors. As the main equipment in the refrigeration system, it converts electrical energy into mechanical work, compresses low - temperature and low - pressure gaseous refrigerants into high - temperature and high - pressure gases, ensuring the operation of the refrigeration cycle.
Compressors are mainly classified into the following types:

Differences between Hermetic and Semi - hermetic Compressors:
Currently, the semi - hermetic reciprocating cold - storage compressor (and now screw compressors are becoming more and more common) is the main type in the market. The semi - hermetic reciprocating cold - storage compressor is generally driven by a four - pole motor, with a rated power usually between 60 - 600KW. The number of cylinders ranges from 2 to 8, and at most 12.
For hermetic compressors, the compressor and the motor it is equipped with share a main shaft and are installed inside a casing. Therefore, there is no need for a shaft seal device, reducing the possibility of leakage.
Advantages:
The compressor and the motor are installed in a casing welded or brazed shut, sharing a main shaft. This not only eliminates the shaft seal device but also greatly reduces and shrinks the size and weight of the entire compressor. Only the suction and exhaust pipes, the service pipe, and other necessary pipes (such as the spray pipe), the power input terminals, and the compressor bracket are welded on the outer surface of the casing.
Disadvantages:
It is not easy to open for repair. Since the entire compressor - motor unit is installed in a non - detachable sealed casing, it is difficult to open for internal repair. Therefore, this type of compressor requires high - reliability in use and a long lifespan. It also has high requirements for the installation of the entire refrigeration system. This hermetic structure is generally used in small - capacity refrigeration compressors produced in large quantities.
Semi - hermetic compressors mostly adopt the integral structure of the cylinder block - crankcase. The motor housing is often an extended part of the cylinder block - crankcase to reduce the connection surface and ensure the concentricity between the compressor and the motor.

In larger models, for the convenience of casting and processing, they are made separable and connected by flanges at the joints. The two spaces of the crankcase and the motor chamber communicate through holes to facilitate the return of lubricating oil.
The main shaft of the semi - hermetic compressor is in the form of a crankshaft or an eccentric shaft. The built - in motor can be cooled by air, water, or the suction of low - temperature working fluid vapor.

For semi - hermetic compressors within a small power range, the lubrication often adopts the centrifugal oil - supply method.
This lubrication method has a simple structure. However, when the power of the compressor increases and there is insufficient oil supply, it is changed to the pressure - lubrication method.
Advantages: