The refrigeration oil is mainly used to lubricate the parts of the freezer that need lubrication. It is closely related to the running performance and service life of the compressor, so its selection and application are very important. Shenzhen Hualai Industrial Engineer summarized several important aspects of the selection of refrigeration oil in the lubrication practice of the refrigerator:
Link 1: Understanding the freezer is the key
The freezer is different from the compressor, so it is not possible to simply replace the refrigeration oil with compressor oil. The freezer can be divided into piston type, screw type, centrifugal type, etc. according to the working form. At the same time, the freezer is one of the most important components of the compression refrigeration equipment.
Step 2: Meeting the lubrication requirements of the freezer is fundamental
1. Due to the working nature of the freezer, when selecting the lubricating oil, it is first selected according to the form of the freezer and the working conditions of the freezer;
2. Because the working condition of the freezer is characterized by high temperature and high speed, it is essential that the selected lubricating oil has good high temperature resistance and anti-emulsification;
3. When selecting the lubricating oil of the freezer, you should also pay attention to the model, grade, manufacturer information and technical parameters of the lubricating oil product to ensure that the original high quality lubricating oil is purchased.
Link 3: Analyze the lubrication part and select the lubricant
1. The main lubrication parts of the freezer are bearings, pistons, piston rings, crossheads, crankpins, oil seals and other parts.
2, the main lubrication methods are, splash or forced circulation;
Link 4: Select factors that should be considered for refrigeration oil
1. Viscosity: The higher the speed of the compressor, the higher the viscosity of the frozen oil should be used. In actual use, the low-speed vertical two-cylinder compressor can use L-DRAl No. 5 refrigeration oil, and the medium-speed and high-speed multi-cylinder compressor should be used. L-DRA22 or L-DRA32 refrigeration oil, some high-speed heavy-duty compressors have large calorific value, high oil temperature and high temperature. It is best to use L-DRA46 or L-DJRA68 refrigeration oil.
2, thermal stability: thermal stability is generally measured by the flash point of the frozen oil. The flash point is the temperature at which the vapor of the frozen oil flashes after the fire. The flash point of the refrigerating oil must be higher than the exhaust temperature of the compressor. For example, the flash point of the refrigerating machine oil used in R717, R12, and R22 compressors should be above 160 °C.
3. Mobility: The frozen oil should have good fluidity at low temperature. In the evaporator, the fluidity is deteriorated due to the low temperature and the viscosity of the oil. When the temperature reaches a certain temperature, the refrigeration oil stops flowing. The temperature is called the freezing point of the oil. The refrigerating machine oil of the refrigerator requires a low freezing point, especially the requirement of the freezing point of the cryocooler for the oil. Otherwise, the fluidity is reduced, which affects both the heat transfer of the evaporator and the lubrication of the machine. The freezing point of various refrigeration oils is below -40 °C, which can meet the needs of general-purpose refrigerators. When the evaporation temperature is low, a precision instrument oil can be used, and the freezing point is generally not higher than -60 °C.