What is magnetic levitation central air conditioning?

Magnetic levitation central air conditioning refers to central air conditioning systems that utilize magnetic levitation frequency conversion technology. It incorporates advanced technologies such as magnetic levitation oil-free operation, full DC frequency conversion, efficient heat exchange tube design, secondary refrigerant supercooling technology, centralized control technology, and aerospace technology. It boasts ultra-high energy efficiency and represents the highest level of energy efficiency in the central air conditioning industry.

The magnetic levitation compressor consists of four major components: compression, drive, frequency conversion, and control. The magnetic levitation centrifugal compressor serves as the core technology. The technology foundation of the magnetic levitation compressor lies in magnetic levitation bearing technology, which combines permanent magnetism with electromagnetism to achieve a nearly perfect six-sided floating state of the shaft. It has been observed that the adoption of magnetic levitation technology notably enhances the overall performance of the compressor.

Firstly, it increases the rotational speed. Without mechanical friction, the theoretical rotational speed of the magnetic levitation compressor can be infinitely high (provided that the impeller strength is sufficient). In practical applications, extremely high rotational speeds have been achieved, enabling the reduction of impeller size which leads to a significant decrease in the overall volume and weight of the compressor.



Next is the implementation of variable frequency drive. Due to the absence of the need for oil return due to lubrication (after the dedicated oil supply pump is canceled, the lubrication of the oil machine depends entirely on the negative pressure generated during operation), the speed of the magnetic levitation compressor can be infinitely small (approaching 0), which enables the full play of the similarity law in the centrifugal mechanical system.

Advantages of Magnetic Levitation Central Air Conditioning

1. High efficiency and energy saving: The oil-free system of magnetic levitation chillers ensures that lubricating oil is not mixed into the refrigerant, thereby improving the heat exchange efficiency of the condenser and evaporator. Compared with traditional bearings, magnetic levitation bearings have a friction loss of approximately 2%, which improves mechanical efficiency. The digital variable frequency control technology of magnetic levitation chillers also improves part load efficiency of the chiller. Operating costs are reduced by 50% compared to traditional chillers. For example, in Beijing data centers, the cooling water supply temperature is 12℃, the return water temperature is 18℃, and the approach temperature of the plate heat exchanger is 2℃. The approach temperature of the cooling tower and wet bulb temperature is 4℃. Based on the "China Building Thermal Environment Analysis Special Meteorological Data Set", the data center air conditioning system operates in partial natural cooling for a total of 1785 hours (out of 8760 hours) per year. As shown in the figure below, magnetic levitation chillers have greater energy-saving potential when data centers are in natural cooling mode.

2. Low starting current: with traditional large chillers, starting currents can reach 200-600 A, which can have a large impact on the power grid. Magnetic levitation chillers adopt variable frequency soft-starting technology, with very low starting currents. After power outages in data centers, multiple chillers can be started simultaneously.

3.Compact structure: Magnetic levitation chillers can achieve a speed of up to 48,000 rpm, while the speed of conventional centrifugal chillers is generally around 3000 rpm. therefore, magnetic levitation chillers have a smaller size and lighter weight compared to traditional chillers.



4. Quiet operation: Magnetic levitation chillers have no mechanical friction, resulting in very low noise and vibration. The compressor noise is below 77 dB, while traditional centrifugal compressors can exceed 100 dB in bare machine noise.

5. High sustainability: In traditional refrigeration compressors, mechanical bearings are necessary components, and a lubrication system is required to ensure their operation. According to statistics, 90% of compressor failures are caused by lubrication failures. Magnetic levitation chillers do not require oil lubrication systems and have no mechanical friction, making them more sustainable compared to traditional chillers. The lifespan advantage of magnetic levitation bearings is that they have no wear, with an air conditioning lifespan of up to thirty years.

6. Low maintenance costs: Magnetic levitation units have fewer moving parts and do not have complex oil systems or oil cooling systems, reducing the maintenance requirements of the chillers. Data center air conditioning systems operate continuously throughout the year, and equipment maintenance is part of daily operations for data center personnel. By using magnetic levitation chillers, the maintenance requirements can be effectively reduced, reducing the workload for operations and maintenance personnel, and effectively lowering the daily maintenance costs.

7.Low operating noise: When a single magnetic levitation compressor operates normally, its noise level is around 68 dBA (at a distance of 1 meter), while traditional screw or centrifugal compressors can exceed 80 dBA in noise level.

Working principle of magnetic levitation compressor

In traditional refrigeration compressors, mechanical bearings are necessary components, and a lubrication oil circulation system is required to ensure the operation of mechanical bearings.



Magnetic levitation refrigeration compressors utilize the principle of magnetic "like poles repel, unlike poles attract." By applying corresponding electromagnetic fields between the rotor and stator of the bearings and controlling these electromagnetic fields, a relative state of "levitation" is achieved. This ensures that there is no mechanical contact or friction during rotation. Therefore, magnetic levitation bearings eliminate the need for mechanical bearings and the lubrication systems required by mechanical bearings.