Refrigeration oil is a lubricant for refrigeration systems. It can maintain good fluidity in low-temperature environments and has good compatibility with refrigerants. The main components of refrigeration oil depend on the type of refrigerant used. Common refrigeration oils include mineral oil, synthetic hydrocarbon oil, polyester oil (POE), etc.
Main function
Lubrication: Refrigeration oil forms an oil film between the moving parts inside the compressor, reducing friction and wear between metals, thereby extending the service life of the compressor.
Cooling: Through circulation, refrigeration oil can help take away the heat generated during the operation of the compressor and play a certain cooling effect.
Sealing: In piston compressors, refrigeration oil can also enhance the sealing between the piston and the cylinder wall and improve compression efficiency.
If lubrication is insufficient, a series of problems may occur, affecting the working efficiency and life of the compressor. The following are typical phenomena of compressor damage caused by insufficient lubrication:
1. The lubricating oil cannot reach the bearing surface
Cause: The oil suction net or oil supply line is blocked: If the oil suction net is blocked by impurities or dirt, or there are foreign objects in the oil supply line, the lubricating oil will not be smoothly transported from the oil tank to the various parts that need lubrication, resulting in increased dry friction and temperature rise, which may eventually cause mechanical damage.
Oil pump failure: The oil pump is the power source that transports lubricating oil from the oil tank to each lubrication point. If the oil pump fails, such as motor burnout, gear wear, poor sealing, etc., the oil pump will not work properly and the lubricating oil will not reach key parts such as bearings.
Unreasonable oil circuit design or improper installation: If there are defects in the design of the oil circuit or problems occur during the installation process, it may also hinder the normal circulation of lubricating oil.
2. Although the lubricating oil has reached the bearing surface, the viscosity is too low
Reason: Lubricating oil with low viscosity cannot form an effective oil film to isolate the metal surface, resulting in increased wear.
Unqualified oil quality: Lubricating oil that does not meet the standards is used, and its viscosity may not be suitable for the working conditions of the compressor.
Liquid return phenomenon: Refrigerant liquid enters the lubricating oil, dilutes the lubricating oil, and reduces its viscosity.
Lubricating oil aging: The performance of the lubricating oil decreases after long-term use, and the viscosity decreases.
3. Although the lubricating oil has reached the bearing surface, it decomposes due to overheating
Reason: After the lubricating oil decomposes, it loses its lubricating effect and can no longer protect the metal surface, thereby accelerating wear.
Lubricant overheating: The heat generated during the operation of the compressor is not dissipated in time, resulting in excessively high lubricant temperature.
Poor lubricant quality: Some lubricants are prone to decomposition at high temperatures.
4. Other factors
Liquid backflow problem: Liquid backflow refers to the refrigerant liquid flowing back into the compressor, which will cause the lubricant to be diluted, thereby affecting the lubrication effect. Long-term liquid backflow will not only destroy the oil film, but also make the additives in the lubricant ineffective, further aggravating wear.
Lubricant decomposition caused by high temperature: When the lubricant temperature exceeds its temperature resistance limit, it will decompose and lose its lubrication function. The decomposition products may form deposits, further affecting the normal operation of the compressor.
In summary, maintaining good lubrication system maintenance habits, regularly checking and replacing lubricants, and ensuring that the compressor operates within the design parameters are effective measures to prevent insufficient lubrication and related problems.
