亚洲AV无码片一区二区三区_

Hot Search: gear oil、Hydraulic oil、High temperature grease、Synthetic oil、Metalworking oil

Contact

Service hotline: 400-688-7804

Tel: 0769-87886500

0769-82621675

Fax: 0769-82621676

Technology: 156-0260-4248 (wechat same number)

Investment promotion: 180-2519-7509 (wechat same number)

Email: jmsha@ssorn.com

jmsh@ssorn.com

website: www.zamrikpi.com

Location:Home > News and information > Industry information > Read

Important factors of selecting refrigeration oil

Pubdate:2019-12-31 10:59:10
According to its structure, the refrigerator can be divided into three types: piston type (or reciprocating), rotary type (including screw type, rotor type and slide type), and centrifugal type (or turbine type). The parts to be lubricated in the piston refrigerator include piston and cylinder wall, connecting rod bearing bush and piston pin or crank pin, main journal and front and rear bearing bush, crankcase, shaft seal and valve, etc. The parts that need to be lubricated in the screw refrigerator include the rotating engagement part of the convex and concave screw, the sliding bearing before and after the screw, the balance piston of the active screw, etc. The parts to be lubricated in the centrifugal refrigerator include the speed increasing gear, main bearing, shaft end sealing surface, etc. Due to reciprocating movement of piston, some lubricating oil may enter into the cylinder and be brought into the system with high-speed gas, and at the same time, due to evaporation of lubricating oil, it may also enter into the system to mix with refrigerant. Most of the mixed lubricating oil can be separated after passing through the separator, and a small amount still enters into the cooler and other equipment with refrigerant. As the temperature decreases, the lubricating oil condenses and forms an oil film attached to the tube wall of the cooler and the system, the heat transfer effect decreases and the temperature of the refrigeration chamber increases. On the other hand, the high-pressure refrigerant gas may leak into the lubricating oil to dilute the lubricating oil. Therefore, the lubricating oil of the refrigerator is different from other mechanical equipment. Because of the different use occasions and refrigerants, the selection of lubricating oil for the refrigerator is also different. In the process of long-term communication with customers, Hualai industry summarized the following requirements for refrigeration oil:
1. Freezing point: freezing point refers to the temperature at which frozen oil cools to stop flowing under experimental conditions. In the refrigeration system, the heat exchange equipment and pipes usually work at low temperature, and there are more or less oil film on the pipe wall. How the freezing point of oil is too high will affect the flow of refrigerant, increase the flow resistance, and affect the heat transfer effect. Generally speaking, for refrigeration equipment, the lower the freezing point, the better. For example, for R-22 compressor, the freezing oil should be below - 55 ℃. If it is used in low temperature device, its freezing point shall be lower.
2. Viscosity: the viscosity of the refrigeration oil is an important parameter in the oil characteristics. Different refrigerants should be selected accordingly. In addition. The viscosity of the lubricating oil is also related to the temperature of the refrigerator. When the temperature increases, the viscosity of the oil will decrease. The viscosity of the lubricating oil in the refrigeration equipment will increase the mechanical friction power, friction heat and starting torque. If the viscosity is too small, the required oil film can not be formed between the moving parts and the proper lubrication and cooling effect can not be achieved.
3. Cloud point: the cloud point of refrigeration oil refers to the temperature when the temperature drops to a certain value and paraffin begins to precipitate in the lubricating oil, making the lubricating oil turbid. The cloud point of the lubricating oil used in the refrigeration equipment shall be lower than the evaporation temperature of the refrigerant. Otherwise, when the paraffin is separated from the lubricating oil, it will accumulate at the throttle valve, which will block the throttle valve, or it may accumulate on the heat transfer surface of the evaporator, affecting the heat transfer performance.
4. Moisture and mechanical impurities: if the lubricating oil contains moisture, it will aggravate the chemical change of the oil, make the oil deteriorate, cause corrosion to the metal, and also cause "ice block" at the throttle valve or expansion valve. The lubricating oil contains mechanical impurities, which will aggravate the wear of the friction surface of the moving parts and quickly block the filter, throttle valve or expansion valve, so the lubricating oil of the refrigerator should not contain mechanical impurities.
5. Flash point: This refers to the lowest temperature at which flash fire occurs when the refrigerant oil is heated to its steam contacts with the flame. The flash point of the lubricating oil used in the refrigeration equipment must be 15-30 ℃ higher than the exhaust temperature to avoid the burning and coking of the lubricating oil. Generally, the flash point of R-12 and R-22 lubricating oil is above 160 ℃.
6. Chemical stability and oxygen resistance: the chemical composition of pure refrigeration oil is stable, does not oxidize, and does not corrode metals. However, when there is refrigerant or water in the lubricating oil, it will produce corrosion. After the lubricating oil is oxidized, it will generate acid and corrode metal. When the lubricating oil is in high temperature, Coke will appear. If this kind of material is attached to the valve plate, it will affect the normal operation of the valve plate, and cause the filter and throttle valve to be blocked. Therefore, it is necessary to choose the lubricating oil with good chemical stability and oxidation resistance.
7. Insulation performance: in semi enclosed and fully enclosed refrigerators, the frozen lubricating oil and refrigerant are directly in contact with the winding and terminal of the motor, so the lubricating oil is required to have good insulation property and high breakdown voltage. Pure lubricating oil has better insulation performance, but when it contains moisture, impurities and dust, its insulation performance will decline. Generally, the breakdown voltage of lubricating oil of refrigerator is required to be above 2.5KV.
8. Due to the different characteristics of various refrigerants, the working temperature of the refrigeration system varies greatly. Generally, the lubricating oil of the refrigerator can be selected as follows: the lubricating oil with small viscosity and low freezing point can be selected for the refrigeration equipment under low-speed and low-temperature conditions; while the lubricating oil with large viscosity and high freezing point can be selected for the refrigeration equipment under high-speed or air-conditioning conditions.
[background management]   [  ] the relevant website materials of this website are all from the Internet. If there is any infringement, please inform us immediately. We will delete the copyright within 24 hours: Dongguan Jinmen Petrochemical Co., Ltd. record No.: yueicp Bei 14070561