1. Basic information
Refrigerant Oil
The oil used for lubrication of the moving parts in the refrigeration compressor is called a refrigerating oil. In the compressor, the refrigeration oil mainly functions as lubrication, sealing, cooling and energy regulation.
2. Function
In the compressor, the refrigeration oil mainly plays the four roles of lubrication, sealing, cooling and energy regulation.
(1) Lubrication The refrigerating oil acts as a lubricant during the operation of the compressor to reduce the friction and wear of the compressor, thereby prolonging the service life of the compressor.
(2) Sealing The refrigeration oil acts as a seal in the compressor to seal the piston between the piston and the cylinder face and between the rotating bearings to prevent refrigerant leakage.
(3) Cooling When the lubricating oil is lubricated between the moving parts of the compressor, it can take away the heat generated during the working process, keeping the moving parts at a lower temperature, thereby improving the efficiency and reliability of the compressor.
(4) Energy adjustment For a refrigeration compressor with an energy adjustment mechanism, the oil pressure of the refrigeration oil can be used as the power of the energy adjustment machine.
3POE and PAG meaning
In order to protect the ozone layer, the refrigerants of air-conditioning equipment have been restricted internationally, and various alternative refrigerants have appeared, and the refrigeration oil has also changed accordingly. The alternative refrigerant for air conditioners is R134a, R410a/R407c, and the alternatives are PAG and POE.
3. POE and PAG meaning
In order to protect the ozone layer, the refrigerants of air-conditioning equipment have been restricted internationally, and various alternative refrigerants have appeared, and the refrigeration oil has also changed accordingly. The alternative refrigerant for air conditioners is R134a, R410a/R407c, and the alternatives are PAG and POE.
York Frozen Oil
POE is the abbreviation of Polyol Ester, also known as polyester oil, which is a class of synthetic polyol ester oils. PAG is an abbreviation for Polyalkylene Glycol, a synthetic poly(B) glycol lubricant. Among them, POE oil can be used not only in HFC-based refrigerant systems but also in hydrocarbon refrigeration. PAG oils are lubricants in refrigeration systems that use HFCs, hydrocarbons, and ammonia as refrigerants.
4. Requirements
Refrigeration equipment has different choices for refrigeration oils due to the use and refrigerant. The requirements for refrigeration oil are as follows:
(1) Freezing point The temperature at which the frozen oil is cooled to the stopped flow under the experimental conditions is called the freezing point. The freezing point of the refrigeration oil used in the refrigeration equipment should be as low as possible (such as the compressor of R22, the refrigeration oil should be below -55 °C), otherwise it will affect the flow of the refrigerant and increase the flow resistance, resulting in poor heat transfer.
(2) Viscosity An important parameter in the characteristics of the oil viscosity of the frozen oil. Different refrigerants should be used to select different refrigerant oils. If the viscosity of the frozen oil is too large, the mechanical friction power, friction heat and starting torque will increase. On the other hand, if the viscosity is too small, the desired oil film cannot be formed between the moving parts, so that the desired lubrication and cooling effect cannot be achieved.
(3) Cloud point The cloud point of the refrigerating oil refers to the temperature at which the paraffin is precipitated in the refrigerating oil when the temperature is lowered to a certain value to make the lubricating oil turbid. The cloud point of the refrigeration oil used in the refrigeration equipment should be lower than the evaporation temperature of the refrigerant, otherwise it will cause the throttle valve to block or affect the heat transfer performance.
(4) Others such as chemical stability and oxidation resistance, moisture and mechanical impurities, and insulation properties.
(5) Flash point The flash point of the frozen oil refers to the lowest temperature at which the lubricating oil is heated until its vapor contacts the flame. The flash point of the refrigeration oil used in the refrigeration equipment must be 15 to 30 °C higher than the exhaust gas temperature to avoid burning and coking of the lubricating oil.
5. Temperature and pressure
The oil temperature should generally be maintained between 45~60 °C, the highest should not exceed 70 °C, and it is stable. If the oil temperature has been unstable and slowly rising, it indicates that there is a fault. If the oil temperature is too low or too high, the lubricating oil will deteriorate. At the same time, it often indicates the arrival of the fault. The key to the pressure of the refrigerating oil is the difference in oil pressure. The oil pump does not oil because of various reasons, that is, the oil pressure difference cannot be established. The oil pressure depends on the structure of the compressor. The external gear oil pressure difference of the vertical compressor is 0.5~1.5MPa, and the new series compressor oil pressure difference is 0.5~1.5MPa. In the operation and commissioning of the newly purchased compressor, the oil pressure difference is often high, so as to increase the amount of lubricating oil, better complete the running-in period of the moving parts such as cylinders, and prolong the service life of the machine.