1. Unit Overview
It is an integrated high‑end energy‑saving chilled‑water host combining air‑bearing oil‑free centrifugal compressor and air‑cooled finned condenser. As a top‑tier energy‑saving air‑cooled model, it inherits the merits of zero‑friction operation and ultra‑low maintenance of oil‑free air‑bearing technology. Meanwhile, it features the installation convenience of air‑cooled units: no cooling tower or cooling water system is required, and the unit can be directly placed outdoors. It serves as a premium energy‑saving solution for water‑scarce regions and renovation projects without dedicated mechanical rooms.
2. Core Structure and Working Principle
2.1 Core Components (Combination of Two Key Technologies)
Air‑Bearing Variable‑Frequency Centrifugal Compressor (the heart)Adopting hydrodynamic air bearings, the high‑speed spinning rotor squeezes air to form a 10‑20 μm high‑pressure air film for levitation. Lubrication‑related components including oil pumps, oil separators and oil filters are completely eliminated. It is equipped with a permanent‑magnet high‑speed variable‑frequency motor with stepless capacity modulation from 10 % to 100 %. R134a is the commonly‑used environmentally‑friendly refrigerant.
Air‑Cooled Finned Condenser (air‑cooled heat‑rejection section)Composed of copper‑tube aluminum‑fin heat‑exchange coils and high‑power top‑mounted axial‑flow fans. Forced air flow dissipates the condensing heat of refrigerant directly to ambient air. No cooling tower, cooling‑water pump or cooling‑water piping is required for the whole system — this is the essential difference from water‑cooled air‑bearing chillers.
Evaporator: Shell‑and‑tube evaporator, producing conventional 7 °C chilled water.
Electronic expansion valve, PLC intelligent control cabinet, with full set of protections including anti‑freezing, high/low pressure, water flow and overload protection.
2.2 Refrigeration Cycle Process
The air‑bearing compressor compresses low‑temperature low‑pressure refrigerant into high‑temperature high‑pressure gas.
The refrigerant flows into the air‑cooled finned condenser, where forced air ventilation liquefies refrigerant with heat rejection.
The electronic expansion valve throttles the refrigerant for pressure and temperature reduction.
The evaporator absorbs heat from chilled water to generate low‑temperature cold water, and gaseous refrigerant returns to the compressor to complete the cycle.
3. Core Advantages and Disadvantages
✅ Key Advantages
1. Combines air‑cooled installation simplicity and oil‑free high energy efficiency
Simple installation: fully integrated unit. Only power supply and chilled‑water piping connections are needed. It can be installed on rooftops, ground floors or terraces. No dedicated mechanical room or civil foundation for cooling towers is required, making it well‑suited for renovation of old buildings.
Zero tap‑water consumption, ideal for water‑scarce cities, areas with poor water quality and projects incompatible with cooling‑water systems.
Far higher energy efficiency than traditional air‑cooled screw chillers: full‑load COP reaches 4.5‑6.0; integrated part‑load value (IPLV) ranges from 8.5‑11.0. It consumes 35 %‑50 % less power than air‑cooled screw chillers under annual part‑load operating conditions.
2. Greatly reduced maintenance costs (shared merit of air‑bearing technology)
No replacement of refrigeration oil, oil filters or oil‑circuit components for service life; minimal annual maintenance workload.
No heat‑resistance degradation caused by lubricant fouling on heat‑exchanger surfaces; heat‑exchange efficiency remains stable long‑term.
Maintenance is limited to regular cleaning of air‑cooled fins and inspection of electrics and water pumps.
3. Excellent operating performance
Zero mechanical friction leads to minimal vibration; overall unit noise is much lower than conventional air‑cooled screw outdoor units.
Soft‑start with extremely low inrush current, imposing little impact on transformers and ageing power grids.
Oil‑free refrigerant circuit free of oil contamination; suitable for pharmaceutical, electronics and clean workshops with strict requirements for water quality and refrigerant purity.
4. More cost‑effective compared with air‑cooled magnetic‑levitation chillers
As another type of oil‑free air‑cooled chiller, the air‑bearing model uses a passive mechanical air‑levitation structure without complex electromagnetic sensors and controllers. It delivers lower failure rates and stronger resistance to voltage fluctuation, with purchase price 5 %‑15 % lower than air‑cooled magnetic‑levitation chillers.
❌ Limitations (critical for model selection)
Obvious efficiency drop under high ambient temperature: above 38 °C ambient temperature in summer, air‑cooled heat‑dissipation capacity declines, leading to derated cooling capacity and efficiency. Under long‑term full‑load conditions, its stability is inferior to water‑cooled air‑bearing chillers. In hot regions of South China, its power consumption under continuous full‑load operation exceeds that of water‑cooled versions.
Restricted chilled‑water supply temperature: it can stably produce chilled water at 6 °C or above. It cannot deliver sub‑zero ethylene‑glycol brine for low‑temperature chemical reactions or cryogenic processes. It is only applicable to conventional 7 °C central air‑conditioning or process constant‑temperature cooling.
Limited single‑unit cooling capacity: typical single‑unit capacity ranges from 75 RT (265 kW) to 300 RT. For large‑scale projects requiring thousands of RT, multiple units must be paralleled, unlike large water‑cooled centrifugal chillers available in high single‑unit capacity.
High initial procurement cost: unit price is significantly higher than ordinary air‑cooled screw chillers. It is only cost‑effective for projects with long annual operating hours; payback period will be too long for seasonal intermittent use.
Outdoor fan‑related noise: exposed fans generate certain noise. Sound barriers and vibration‑reduction treatments are required for installations adjacent to buildings.
4. Comparison of Four Mainstream Chillers
| Comparison Item | Air‑Cooled Screw Chiller | Water‑Cooled Screw Chiller | Water‑Cooled Air‑Bearing Chiller | Air‑Cooled Air‑Bearing Chiller |
|---|
| Lubrication | Oil pump feed; periodic oil change | Oil pump feed; periodic oil change | Oil‑free air‑bearing | Oil‑free air‑bearing |
| Heat Rejection Mode | Air‑cooled | Cooling‑tower water‑cooled | Cooling‑tower water‑cooled | Air‑cooled |
| Cooling Tower Required | No | Mandatory | Mandatory | No |
| IPLV | 3.0‑4.2 | 5.0‑6.0 | 9.0‑11.0 | 8.5‑10.5 |
| Annual Maintenance Cost | Medium | High (tube cleaning + oil change) | Extremely low | Extremely low |
| Water Consumption | Nearly zero | High make‑up water | High make‑up water | Nearly zero |
| High‑Temperature Stability | Poor | Excellent | Excellent | Poor |
| Minimum Supply Water Temperature | Sub‑zero low‑temperature available | Sub‑zero low‑temperature available | ≥6 °C | ≥6 °C |
| Initial Investment | Medium | Medium (high auxiliary‑equipment cost) | Very high | Very high |
5. Target Application Scenarios
5.1 Commercial Central Air‑Conditioning (Core Application)
Office buildings, shopping malls, hotels and industrial parks in water‑scarce regions, where rooftop load capacity is adequate, cooling‑tower installation is prohibited, and systems operate at high load all year round. Users expect air‑cooled ease‑of‑installation plus ultra‑low operating power cost.
5.2 Industrial Process Cooling
Constant‑temperature chilled water for lithium‑battery, photovoltaic and precision‑electronic workshops (oil‑free system avoids contamination risk).
Process cooling water for pharmaceutical and food clean workshops.
Centralized cooling for production plants without water‑supply‑drainage infrastructure or space for cooling‑water piping trenching.
5.3 Energy‑Saving Retrofit Projects
Replacement of ageing air‑cooled screw chillers; price premium can be recovered within 2‑3 years through electricity savings. Also for temporary large‑scale venues and edge‑node data‑center outdoor cold sources.
5.4 Projects with Constrained Civil‑Engineering Conditions
Projects without dedicated chiller rooms, limited rooftop footprint, cooling‑tower installation forbidden by property owners, or northern sites where cooling‑water circuits risk winter freeze rupture ruling out water‑cooled solutions.
6. Key Selection Parameters
Nominal cooling capacity (kW / RT); implement redundant configuration via multiple parallel units.
Chilled‑water supply/return temperature: standard 7 °C / 12 °C; supply temperature below 6 °C is not recommended.
High‑ambient‑temperature operating performance: prioritize units capable of stable operation at 43 °C ambient temperature.
Refrigerant: R134a as primary option; low‑GWP eco‑friendly refrigerant optional.
Optional features: variable‑speed fan drive, IoT remote monitoring, winter water‑circuit anti‑freezing protection.
Verification of rooftop load‑bearing capacity, outdoor‑unit ventilation clearance and power‑distribution capacity.
7. Routine Maintenance Guidelines
Top priority: thoroughly flush air‑cooled condenser aluminum fins at seasonal transitions. Blockages from dust and catkins will trigger excessive high pressure and sharp efficiency loss.
Inspect top axial‑flow fan bearings, variable‑frequency modules and tighten electrical connections.
For winter shutdown: drain water circuits completely or add antifreeze for freeze protection.
No refrigeration‑oil or oil‑filter replacement required; only general routine inspections are needed.
Selection Guidance
1.Choose air‑cooled screw chiller: limited budget, intermittent operation, demand for low‑temperature chilled water.
2.Choose water‑cooled air‑bearing chiller: sufficient water resource, dedicated mechanical room available, pursuit of maximum energy‑saving performance.
3.Choose air‑cooled air‑bearing chiller: water‑scarce sites / no cooling‑tower allowed, long annual operating hours, expecting air‑cooled plug‑and‑play and oil‑free low‑maintenance operation.
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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