10 Benefits of Magnetic-Bearing Compressor Chillers

Over twenty years ago, the first chiller with magnetic bearing compressors was installed. The compressor was originally designed circa 25 years ago, specifically for the Heating, Ventilation, Air Conditioning and Refrigeration (HVACR) industry. The original designer also had a passion for engines, hence they look like a V8! But that’s where the similarity to an internal combustion engine ends.

The use of oil-free compressors with non-contact magnetic levitation bearings results in higher efficiencies, less complexity and reduced chiller maintenance – read on to explore the 10 main benefits of magnetic-bearing compressor chillers…

1. Energy Efficiency & Environmental Protection

Magnetic-bearing compressors have excellent EER (Energy Efficiency Ratio) values, especially at part loads, providing a reduction in operating costs of up to 50%.

Environmentally-friendly refrigerant choices are available, including the low GWP (Global Warming Potential) refrigerant R513A and the ultra-low GWP refrigerant R1234ze. With economisers as standard, maximum output can be ensured with minimum refrigerant charge.

2. Variable Control

In a 4-month study of a real air conditioning application with chilled water at 13°C / 7°C and cooling water at 28°C / 33°C, the data proved up to 50% better EER values (left) and 50% less to generate cooling (right).

The variable control modulates to partial and full loads, be it a water or air-cooled chiller. Optional flow meters, energy meters and EER or COP can be provided to prove savings for grants or internal kW and carbon monitoring and targeting.

3. Oil-free Compressor with non-contact Magnetic Bearings

Thanks to the oil-free compressor technology, magnetic-bearing chillers do not suffer any loss in performance efficiency. The radial and axial magnetic bearings levitate the shaft, thereby eliminating metal-to-metal contact, and thus eliminating friction and the need for oil. Each bearing position is sensed by position sensors to provide real-time repositioning of the rotor shaft, they are controlled by onboard digital electronics (BMCC Bearing Motor Compressor Control board). Furthermore, oil-related compressor components for circulation, cooling and filtration are unnecessary.

4. Smooth Start-up

The magnetic-bearing compressor does not have an abrupt start. It starts gradually and then proceeds smoothly, driven by the integrated Variable Speed Drive (VSD), with a maximum start-up current of 5 amps.

The electrical supply network therefore remains stable as there are no voltage peaks during the activation. Furthermore, the capacity control increases the electrical power input steadily and smoothly.

This start-up profile allows the design of the electro-technical supply line to be based on the operating point, without running the risk of overheating.

5. Minimal Noise & Vibration

The minimal noise level and practically vibration-free operation require no further reduction measures. There is no danger of refrigerant leakage or component damage due to vibration. There is no need for additional spring-mounted bases as no vibration is transmitted to the building structure.

6. Carbon Emissions & Electrical Energy Savings

Energy savings are obtained from day one. Over a 15-year period, a magnetic-bearing compressor with a cooling capacity of 1.4 MW will emit approximately 500 tons less CO₂ than a similar capacity compressor. This is an energy saving of 53,700 kW. Even greater savings are possible, both energy and financial savings.

7. No need for Power Factor (PF) Correction

A magnetic-bearing compressor consumes minimal current across full motor speed range due to the high-power factor value (0.92). Therefore, expensive capacitor banks for PF correction are not necessary. This avoids additional space requirements and the cost of the PF correction equipment.

8. Heat Recovery

The heat energy released by the chiller, which would normally be dumped into the atmosphere, can instead be used to heat a different process or area. Note that for an energy-efficient chiller, a minimal amount of additional energy is required to cool a system. Due to high efficiencies, particularly during partial loads, there is less heat generated from a magnetic-bearing chiller. The ideal chiller cools with minimal energy consumption.

9. Reliability

The availability of a chiller with multiple compressors is considerably higher. Multi-compressor design, combined with highly reliable compressors minimises the unexpected service shutdown versus the single compressor chillers of traditional designs. Even in the unlikely event of one compressor defect or failure, the rest of the chiller can continue operating, ensuring critical services are maintained.

Furthermore, each compressor can be replaced easily, even during chiller operation, thanks to the compact and simplified design of the power and refrigerant circuits.

10. Service & Maintenance

Not only are electrical costs minimal during operation, but the easy servicing of a smooth-running, oil-free system also results in the elimination of the maintenance costs associated with oil service.

The simple and robust design leads to a reduction in the number of components, making them easier to access, therefore reducing service and maintenance activities.

Total Cost of Ownership of Chillers after 2 years

The above benefits also apply to heat pumps with magnetic bearing compressors at their core. Using a “high lift” (greater pressure ratio) compressor in a heat pump, a hot water temperature of 65°C can be achieved, allowing for heat recovery or energy harnessing from the environment.

Sirus is a partner of Engie Refrigeration, supplying and installing magnetic-bearing chillers and heat pumps in Ireland – Contact us for more information. Our Applications Engineers are on hand to discuss the suitability of magnetic-bearing chillers or heat pumps for your energy-efficiency project. Let’s save energy and carbon together.