Semi closed piston refrigeration compressor | Medium high temperature cold storage refrigerant matching and load accounting method
The first paragraph: The semi enclosed piston refrigeration compressor is suitable for medium and high temperature conditions of -5 ℃~15 ℃, with a volumetric efficiency in the range of 78%~86%. It is widely used in fruit and vegetable preservation and edible mushroom cold storage projects.
On the structure of the semi closed piston refrigeration compressor, the motor and compression chamber are enclosed in the same shell, relying on refrigerant to cool the motor. Compared with the open type model, the probability of refrigerant leakage is reduced by 65%. The semi enclosed piston models of Xitelidou are divided into small four cylinder, medium four cylinder, and large four cylinder specifications, suitable for different storage capacities of fresh-keeping cold storage.
The evaporation temperature range for medium to high temperature conditions is often set between 0 ℃ and 10 ℃. R404A and R507 are the mainstream refrigerants in this scenario, while R32 is only used on specific heat pump matched chillers, with an exhaust temperature about 12K higher than R507.
When calculating the load of the cold storage, the cooling load of each cubic meter of fruit and vegetable preservation warehouse is taken as 80-120W, and the total load of a 100 cubic meter fruit and vegetable preservation cold storage is about 8-12 kW. Matching it with a 3-5 horsepower semi closed piston compressor can meet the basic requirements.
There is a requirement for heat exchange margin when the compressor is matched with the air cooler. For medium and high temperature preservation scenarios, it is recommended to increase the heat exchange area of the air cooler by 15% according to the theoretical value to avoid continuous fluctuations in suction pressure caused by the intrusion of door opening heat.
The normal range of compressor discharge pressure fluctuates with the condensing temperature. When condensing at 32 ℃, the high pressure of R507 unit remains stable at 14-16 bar. Continuous operation beyond 18 bar will accelerate valve plate fatigue loss.
The maintenance cycle of a semi closed piston compressor is strongly related to the load. When operating at 70% load, the sampling and testing cycle for refrigeration oil is 2500 hours, the oil filter is replaced synchronously, and the valve plate inspection cycle is 10000 hours.
Many foreign trade purchases are prone to confusion between medium and high temperature compressors and low-temperature compressors. The upper limit of pressure ratio for medium and high temperature models is 8, which makes it difficult to operate stably for a long time below -25 ℃, forcing the use of volumetric efficiency to drop below 45%.
Inquiries for Southeast Asian fruit and vegetable preservation projects account for 41% of the export volume of medium and high temperature compressors. Engineering companies prefer complete sets of compression condensing units to reduce on-site assembly workload and shorten cold storage commissioning time.
Domestic semi enclosed compressors can be used as an alternative to imported models, with a basic cooling capacity deviation controlled within ± 4% for models with the same cylinder diameter and speed, meeting the replacement and renovation needs of most fresh-keeping cold storage facilities.
When purchasing compressors for two equipment factories and cold storage panel factories, priority should be given to confirming the power supply system. The mainstream in Vietnam and Thailand is 415V/50Hz, while domestic models are mostly 380V/50Hz. The motor winding parameters cannot be directly mixed.
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FAQ
What is the upper limit of the evaporation temperature of a medium high temperature semi closed piston compressor? The maximum evaporation temperature of conventional models is 18 ℃, which is mostly used for cold water and preservation conditions.
2. What is the appropriate compressor size for a 100 cubic meter fruit and vegetable preservation warehouse? Match 3 to 5 semi enclosed piston compressors under conventional insulation.
What is the normal range of high pressure for R507 refrigerant unit? When condensing at 32 ℃, maintain high pressure stability within the range of 14-16 bar.
How long does it take to check the refrigeration oil of a semi closed piston compressor? Continuous operation at 70% load, it is recommended to take samples for testing every 2500 hours.
Can the medium high temperature compressor be directly used for frozen meat? Not suitable, insufficient pressure ratio, significant efficiency degradation at low temperatures.
What should be paid attention to when exporting fresh-keeping compressors to Southeast Asia? Vietnam and Thailand mostly use 415V 50Hz, and it is necessary to verify the motor parameters.
What are the advantages of a semi closed piston over an open type leakage? The probability of refrigerant leakage under the same operating conditions is reduced by 65% compared to the open type.
