The compression method of traditional centrifugal chillers (fixed frequency single-stage compression, mechanical bearings) has problems such as high energy consumption, poor adaptability, and complex maintenance. Based on this, the application of multi-stage compression, variable frequency compression, and magnetic levitation technology effectively improves the refrigeration performance of the unit and ensures safe and stable operation in a wider range of application scenarios.
1、 Multi level compression Multi stage compression addresses the problem of excessive pressure difference in traditional single-stage compression by dividing the compression process of refrigerant from low pressure to high pressure into 2 to 3 stages (two-stage compression or multi-stage compression). Through the step-by-step completion technology of "compression cooling recompression", the energy consumption of the unit is effectively reduced while controlling the discharge temperature of the compressor from being too high. Its core is the segmented compression technology.
Traditional single-stage compression requires compressing the refrigerant from low pressure to high pressure at once. When the pressure difference is too large, the high compression ratio leads to high energy consumption and high exhaust temperature, which reduces the performance of lubricating oil and leads to a vicious cycle of compressor overheating.
When using multi-stage compression, there are 2 to 3 sets of impellers inside the compressor. Each set of impellers compresses the refrigerant to a certain pressure, mixes and cools it with the intermediate air supply, and then proceeds to the next stage of compression until the last set of impellers completes the final pressure increase.
Through multi-stage segmented compression of "compression cooling recompression", the pressure burden of each stage is reduced, not only avoiding single-stage pressure overload, but also reducing the final exhaust temperature through intermediate cooling, thereby ensuring the safe and stable operation of the compressor.
The function of multi-stage compression is to improve compression efficiency, with a small pressure difference between each stage and a total energy consumption reduction of 10% -15%. The second is to control the exhaust temperature, cooling it multiple times to keep the exhaust temperature below 60 ℃, ensuring the safe and stable operation of the unit.
Multi stage compression is suitable for places with high cooling capacity and high pressure, such as large hotels (with high total cooling demand and complex systems), large industrial plants (such as automobile factories, chemical plants, etc.), and regional cooling projects (requiring high pressure for long-distance transportation).
Centrifugal chillers are usually used in large and medium-sized projects with high cooling demand. Due to the requirements of performance and stable operation, multi-stage compression centrifugal chillers are mostly used in engineering.
2、 Variable frequency compression
Variable frequency compression is a technology that adjusts the compression amount of refrigerant according to demand by adjusting the motor speed of the compressor through variable frequency. Its core is "on-demand speed regulation" to avoid energy waste caused by fixed speed.
Traditional fixed frequency compression can only operate at a fixed speed, and even when the cooling demand is low, it operates at full load, resulting in energy waste and damage to equipment life due to frequent start stop cycles.
Variable frequency compression adds variable frequency speed regulation function on the basis of fixed frequency. By changing the power supply frequency of the motor through the frequency converter, the motor speed can be adjusted according to the cooling demand.
Variable frequency compression increases the frequency of operation during high cooling demand daytime, causing the motor to run quickly to increase the compression capacity of the compressor on the refrigerant, thereby improving the cooling capacity. Reduce the frequency of operation at night when the cooling demand is low, slow down the motor to reduce the compression of refrigerant by the compressor, thereby reducing the cooling capacity.
Compared to fixed frequency operation, variable frequency operation significantly improves energy efficiency during operation, avoiding the waste of "full load but not needed", and can reduce energy consumption by 30-50% under partial load. On the other hand, it can reduce the start stop of the unit, avoid motor impact, and extend the equipment life by 2-3 years.
Variable frequency compression is suitable for places with large fluctuations in cooling load, such as office buildings (with large differences in demand between weekdays and weekends, day and night), shopping malls (with large differences in pedestrian flow between weekdays and holidays), and data centers (requiring precise temperature control and adjustment to avoid excessive energy consumption).
3、 Magnetic levitation technology
The magnetic levitation compressor uses magnetic levitation technology to replace traditional mechanical bearings, utilizing electromagnetic force to make the compressor rotor operate in a suspended state without mechanical contact friction, thus eliminating the need for lubricating oil. Its core is contactless operation, reducing noise, lowering maintenance requirements, and improving efficiency.
Traditional compression uses mechanical bearings, which cause friction during operation (energy consumption, noise generation), and require regular replacement of lubricating oil (maintenance is complicated). Magnetic levitation technology uses electromagnetic force to suspend the rotor without mechanical contact, thus completely solving these problems.
The principle of magnetic levitation technology is to generate a magnetic field by energizing the electromagnetic coils around the rotor, accurately lifting the rotor so that it does not come into contact with the stator and housing. By adjusting the magnetic field in real-time through the control system, it ensures that there is no deviation during high-speed operation, no friction throughout the entire process, and no need for lubricating oil.
The application of magnetic levitation technology is characterized by low noise, which can achieve ultra quiet sound of 45-50 decibels, which is quieter than speaking. The second is low maintenance, without the need to replace lubricating oil, which can reduce maintenance costs by about 60%. The third is high efficiency, with no friction loss during operation, resulting in a 20-30% increase in efficiency compared to traditional methods.
Magnetic levitation centrifuges are suitable for places with high requirements for noise, maintenance, and efficiency, such as hospital wards, operating rooms (requiring quietness and avoiding frequent maintenance), laboratories (equipment afraid of vibration noise), high-end office buildings, and hotels (pursuing comfort and low operating costs).
To summarize, the above three compression technologies for centrifugal chillers, multi-stage compression means "efficient boosting", variable frequency compression means "energy-saving adaptation", and the core of magnetic levitation technology is "low noise and low maintenance".
For more motor knowledge, please contact Zhejiang Konte Motor Technology Co., Ltd