Introduction to the types of refrigeration compressors in cold storage:
There are many types of cold storage compressors. It is the main equipment in the refrigeration system. It converts electrical energy into mechanical work and compresses low-temperature and low-pressure gaseous refrigerant into high-temperature and high-pressure gas to ensure the refrigeration cycle.
Compressors are mainly classified into the following categories:
1. Semi-hermetic refrigeration compressor: The cooling capacity is 60-600KW, which can be used in various air-conditioning and cold storage refrigeration equipment.
2. Totally enclosed refrigeration compressor: The refrigeration capacity is less than 60KW, and it is mostly used in air conditioners and small cold storage refrigeration equipment.
3. Screw refrigeration compressor: Refrigeration capacity is 100-1200KW, which can be used in large and medium-sized air conditioners and cold storage refrigeration equipment.
The difference between hermetic and semi-hermetic refrigeration compressors:
The current market is mainly semi-hermetic piston cold storage compressors (now more and more screw compressors), semi-closed piston cold storage compressors are generally driven by four-pole motors, and their rated power is generally between 60-600KW. The number of cylinders 2–8, up to 12.
The fully enclosed compressor and the motor used share a main shaft and are installed in the casing, so the shaft sealing device is not needed, which reduces the possibility of leakage.
advantage:
The compressor and the motor are installed in a welded or brazed shell, and share a main shaft, which not only cancels the shaft sealing device, but also greatly reduces and reduces the size and weight of the entire compressor. Only the suction and exhaust pipes, process pipes and other necessary pipes (such as spray pipes), input power terminals and compressor brackets are welded on the exterior of the casing.
shortcoming:
It is not easy to open and repair. Since the entire compressor motor unit is installed in a sealed casing that cannot be disassembled, it is not easy to open for internal repairs. Therefore, this type of compressor is required to have high reliability and long life. The installation requirements are also high, and this fully enclosed structure is generally used in small-capacity refrigeration compressors produced in large quantities.
Semi-hermetic compressors mostly use the overall structure of the cylinder block and crankcase, and the motor casing is often an extension of the crankcase of the cylinder block to reduce the connection surface and ensure the concentricity between the compressor-level motors; For the convenience of casting and processing, it is made separable, and is connected by flanges at the joints. The crankcase and the motor room are connected by holes to facilitate the return of lubricating oil.
The main shaft of the semi-hermetic compressor is in the form of a crank shaft or an eccentric shaft; some of the built-in motors are cooled by air or water, and some are used to inhale low-temperature working medium vapor. For semi-hermetic compressors in the small power range, centrifugal oil supply is often used for lubrication.
This kind of lubrication method has a simple structure, but when the compressor power increases and the oil supply is insufficient, the pressure lubrication method is changed.
advantage:
1. Can adapt to a wider pressure range and refrigeration capacity requirements;
2. The thermal efficiency is high, and the unit power consumption is less, especially the existence of the gas valve makes the deviation from the design condition more obvious;
3. The material requirements are low, and ordinary steel materials are often used, which is easier to process and relatively cheap;
4. The technology is relatively mature, and rich experience has been accumulated in production and use;
5. The installation system is relatively simple.
The above-mentioned advantages of the semi-hermetic piston compressor make it the most widely used and the largest production batch type of refrigerators in various refrigeration and air-conditioning devices, especially in the range of medium and small cooling capacity. At the same time, the semi-hermetic piston compressor not only maintains the advantages of easy disassembly and repair of the open compressor, but also cancels the shaft sealing device, which improves the sealing condition. The unit is more compact and has low noise. When the working fluid cools the motor, it is beneficial to the miniaturization and weight reduction of the machine.
At present, semi-hermetic piston refrigeration compressors such as R22 and R404a for medium and low temperature are widely used in cold storage, refrigerated transportation, freezing processing, display cabinets and kitchen refrigerators.
Post time: Feb-18-2022
