1. Definition
The air‑bearing water‑cooled chiller is an oil‑free variable‑speed centrifugal chiller. Its core component is a high‑speed permanent‑magnet variable‑frequency centrifugal compressor equipped with air‑bearing (dynamic/static‑pressure type). Micron‑scale high‑pressure air film is generated by high‑speed rotation of the rotor to support the rotating shaft. The unit adopts an oil‑free system with zero mechanical friction. It is equipped with shell‑and‑tube condenser and shell‑and‑tube evaporator, and must be matched with cooling tower, cooling water pump and chilled‑water pump. It shall be installed inside the refrigeration machine room.
Two types of air‑bearings:
Dynamic‑pressure air‑bearing (mainstream type): Air film is formed by air compression from high‑speed rotor rotation. No external air supply is required with purely mechanical structure. The rotor lands on protective bearings during shutdown.
Static‑pressure air‑bearing: Equipped with a micro air supply unit. The rotor is lifted by air supply before startup to reduce start‑stop impact, suitable for working conditions with frequent start‑stop cycles.
2. System Composition
Air‑bearing centrifugal compressor: Permanent‑magnet high‑speed variable‑frequency motor with oil‑free air‑bearing; capacity is steplessly adjustable from 5% to 100%.
Shell‑and‑tube condenser (water‑cooled): Condensation heat is carried away by cooling water and rejected to the cooling tower.
Shell‑and‑tube evaporator: Produces 7 °C conventional air‑conditioning chilled water.
Electronic expansion valve, PLC touch‑screen control system, complete protections for high/low pressure, water flow, freeze‑protection and anti‑surge.
Auxiliary peripherals: Cooling tower, cooling‑water pump, chilled‑water pump, expansion tank, water‑treatment equipment.
3. Key Performance Parameters
(Standard working condition: chilled water 7 °C /12 °C; cooling water 30 °C /35 °C)
Unit cooling capacity: approx. 265 kW‑2100 kW (75‑600 RT)
Full‑load COP: 5.5‑6.8
Integrated part‑load value IPLV: 8.5‑10.0
Soft‑start starting current: approx. 2 A, minimal impact on power grid
Noise level: 65‑70 dB(A), extremely low vibration
Main refrigerants: R134a, R513A, low‑GWP eco‑friendly refrigerants
Water‑supply limitation: Stable outlet water temperature ≥6 °C; cannot provide low‑temperature glycol brine for sub‑zero process cooling.
4. Main Advantages
Oil‑free high efficiency with non‑degrading heat‑transfer performanceEliminates refrigeration oil, oil separator and oil filter. No oil‑film fouling on heat‑exchanger surfaces to maintain long‑term heat‑transfer efficiency. Compared with water‑cooled screw chillers, comprehensive energy saving reaches 30%‑50%, ideal for long‑term continuous‑operation projects.
Low maintenance workloadNo refrigeration oil or oil‑related consumables to replace. Annual work is limited to heat‑exchanger cleaning and electrical inspection. Maintenance cost is around 1/3 of that for screw chillers.
Strong tolerance to power‑grid fluctuationPurely mechanical air‑bearing structure, without massive electromagnetic sensors and closed‑loop controllers used in magnetic‑bearing units. Lower failure rate under voltage fluctuation and harmonic distortion with improved reliability.
Low vibration and low noise; complex vibration‑isolation foundation is unnecessary. Multiple compressors can be paralleled for mutual redundancy.
Initial investment is 5%‑15% lower than magnetic‑bearing chillers, delivering outstanding whole‑life‑cycle cost‑performance.
5. Inherent Drawbacks & Selection Constraints
Incapable of low‑temperature process duty. Cannot produce‑5 °C ~‑25 °C low‑temperature glycol brine. Not applicable for chemical low‑temperature processes; screw chillers shall be adopted for such applications.
Limited maximum single‑unit cooling capacity; multi‑unit parallel connection is required for extra‑large‑capacity projects.
Significant efficiency drop under part‑load below 30% (compared with magnetic‑bearing chillers).
Higher initial cost than conventional water‑cooled screw chillers. Suitable for projects with long annual operating hours; payback period becomes long for intermittent‑operation projects and not recommended.
Water‑cooled type requires machine room and cooling tower with water consumption; heat exchangers need regular tube‑cleaning for scale removal.
6. Application Scenarios
✅ Recommended Applications
Large‑scale commercial buildings: shopping malls, office buildings, hotels and hospitals for central air‑conditioning.
24‑hour continuous‑operation facilities: IDC data centers and computing power rooms.
Clean‑process workshops: lithium‑battery, pharmaceutical and electronic clean‑rooms requiring constant‑temperature chilled water.
Energy‑saving retrofits: Replacement of old water‑cooled screw chillers; premium equipment cost can be recovered via energy‑saving benefits.
❌ Not‑Recommended Applications
Chemical and low‑temperature processes requiring low‑temperature glycol brine.
Small‑scale projects with short annual operating hours and intermittent operation.
7. Comparison: Air‑Bearing vs Magnetic‑Bearing vs Water‑Cooled Screw Chiller
| Comparison Item | Air‑Bearing Water‑Cooled Chiller | Magnetic‑Bearing Water‑Cooled Chiller | Water‑Cooled Screw Chiller |
|---|
| Bearing / Suspension | Air‑film bearing, purely mechanical | Active electromagnetic suspension, closed‑loop electronic control | Mechanical sliding bearing, lubricated‑oil system |
| IPLV | 8.5‑10.0 | 10.0‑12.1 | 6.0‑7.5 |
| Low‑load performance | Efficiency drops below 30% load | High efficiency maintained down to 5% load | Step / variable‑frequency regulation, oil‑film thermal resistance exists |
| Power‑grid adaptability | Strong, resistant to voltage fluctuation | Poor, sensitive to power‑supply quality | General |
| Oil‑system maintenance | Oil‑free, no oil‑related maintenance | Oil‑free, no oil‑related maintenance | Refrigeration oil & oil‑filter replacement required annually |
| Low‑temperature glycol duty | ❌ Not available | ❌ Not available | ✅ Available |
| Procurement cost | Medium‑high | Highest | Medium |
8. Maintenance Guidelines
Clean condenser and evaporator tubes annually for scale removal; implement water‑treatment chemical dosing and blow‑down for cooling tower.
Periodically inspect variable‑frequency modules and control system; no oil‑system maintenance required.
Freeze‑protection for water circuit in winter: Add antifreeze glycol or drain piping.
Monitor cooling‑water temperature to avoid chiller surge.
Selection Rule
Choose air‑bearing water‑cooled chiller for projects with machine room and cooling tower, continuous‑year‑round operation, oil‑free low‑maintenance expectation and ordinary power‑grid conditions.Select magnetic‑bearing chiller for sufficient‑budget projects with heavy‑load fluctuation pursuing ultimate energy efficiency.Select water‑cooled screw chiller if low‑temperature process cooling is required.
Precautions for Unit Use
Installation precautions
1. When lifting, positioning, and installing the unit, safety must be taken into account to prevent collisions and ensure the integrity of the equipment.
2.If the unit is installed outdoors, efforts should be made to avoid exposure to wind and rain (except for rainproof types), direct sunlight, or other heat sources that directly radiate; The computer room environment must be kept dry, clean, and ensure good ventilation, leaving space for unit maintenance and upkeep.
3. For air-cooled units, please ensure that there are no obstructions around the unit and reserve 1 meter of space; There is no obstruction within 2 meters of the top of the unit to ensure good ventilation.
4. It is recommended to install the unit on a strong and level ground, and install shock-absorbing rubber pads under the unit chassis to correct the level of the unit. If there are anchor bolts, they must be installed and fixed.
5. The circulating water pump used in conjunction with the unit should be selected and installed according to the data requirements such as water flow rate and water resistance required by the unit.
6. The water pump must be installed in front of the inlet of the unit, and it is recommended to install a filter at the inlet of the water pump to prevent foreign objects from entering the heat exchanger of the unit; If the unit is installed in areas with poor water quality, water treatment must be carried out first to avoid damage to the heat exchanger.
7. It is recommended to install valves, water pressure gauges, thermometers, water flow switches, and other equipment for the water pipeline system connecting the unit, in order to facilitate the inspection and maintenance of the unit's daily operation.
8.To prevent air from being trapped in the water system, the air must be completely discharged before starting the compressor.
9. The chilled water pipeline must be insulated properly to avoid loss of cooling capacity, condensation, and freezing.
10. The weight of the system connection pipeline shall not be borne by the machine body. Rubber shock-absorbing flexible joints and gate valves shall be installed at the inlet and outlet of the unit to avoid vibration and facilitate maintenance.
11.When configuring wires for the unit, wires with slightly larger cross-sections (with margin) should be selected according to the power consumption, and reliable electronic control components and grounding power sources should be installed to prevent accidents such as overload and leakage.
12. As the unit is equipped with reverse phase and phase loss protection, attention must be paid to whether the line phase is correct during wiring installation. The unit cannot operate normally when the phase is misconnected or missing.
13. The operator of the unit must observe the operation status of the unit at all times. Once any abnormal situation is found, please promptly troubleshoot. Forced operation will inevitably cause damage to the unit.
Precautions for operation:
1. Before starting up, check whether all water outlets and pipelines of the unit have been correctly installed and connected.
2. Before starting up, check if the power supply of the unit is connected and if the phase sequence is correct.
3. Before starting up, ensure the safety of the power and water sources. Please carefully refer to the equipment operation manual and strictly follow the instructions for use and operation.
Maintenance precautions:
1. Regularly replace the water in the water tank (it is recommended to replace it every 2 months).
2. Regularly clean the radiator of the unit. For air-cooled units, it is recommended to clean the radiator every 3 months; It is recommended to clean the shell and tube condenser and cooling tower of water-cooled units every 6 months (if the usage environment or water quality is poor, it is recommended to shorten the cleaning cycle).
3.If the unit is not used for a long time, please turn off the main power supply; When the ambient temperature is below 0 ℃ and the unit is shut down for more than 6 hours, the unit and pipelines may freeze, and the damage caused by this is not covered by the warranty.
The best way to avoid pipeline freezing is to completely drain all the water in the unit system!
4. Regularly check the water quality on site to ensure that the water source is qualified (pH ≈ 7). If it contains corrosive substances and causes damage to the unit, it is not covered by the warranty.
5.When the unit encounters unavoidable faults during use, please inform our company of the unit model, component name, and other information so that we can provide you with services more quickly.
6.During the warranty period, our company promises to provide free maintenance services for the unit (excluding human damage, improper use, natural disasters, and uncontrollable factors).
Warning: This unit is a high-voltage, highly specialized mechanical equipment, and should be operated correctly by professional technicians strictly in accordance with the "User and Installation Manual".
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