Air-Cooled Screw Chillers for Industrial and HVAC Projects
GESON selects air-cooled screw chillers by cooling load, entering and leaving fluid temperatures, design flow, fluid or glycol concentration, maximum outdoor ambient, load profile and power supply. These conditions determine actual capacity, compressor lift, fan duty and energy use; a nominal tonnage alone does not define the operating result.
An air-cooled configuration rejects heat directly to outdoor air, so it does not require a cooling tower or condenser-water loop. It still requires an engineered chilled-fluid circuit, correct airflow clearances, electrical infrastructure, freeze protection and service access. GESON can evaluate single- or multiple-circuit configurations for process cooling and larger chilled-water systems.
How an Air-Cooled Screw Chiller Works
The evaporator transfers heat from the chilled fluid into the refrigerant. A screw compressor raises refrigerant pressure and temperature; condenser coils and fans then reject the absorbed heat plus compressor input to outdoor air. The expansion device reduces refrigerant pressure before it returns to the evaporator.
The screw compressor is one part of the selection. The evaporator, condenser coil, fan system, refrigerant circuit and controls must all be rated for the same project conditions.
- Evaporator side: entering/leaving temperature, flow, glycol concentration, pressure drop and fouling allowance.
- Air side: maximum and minimum ambient, altitude, coil cleanliness and recirculation risk.
- Refrigeration side: compressor operating envelope, refrigerant, circuit staging and expansion control.
- Electrical side: voltage, phase, frequency, starting method, running current and site protection.
Rated Capacity: What a 50-Ton or 300-Ton Request Really Means
“50 ton” and “300 ton” describe nominal cooling duty, not a complete chiller specification. One refrigeration ton equals 12,000 Btu/h, but the selected unit must deliver the requested load at the project’s fluid and ambient conditions. Lower leaving-fluid temperature, glycol, higher ambient temperature and altitude can change available capacity and input power.
| Selection item | What the quotation should state |
|---|---|
| Net cooling capacity | Capacity at specified entering/leaving fluid temperatures, flow and fluid composition. |
| Outdoor design point | Maximum dry-bulb temperature and altitude used for the selection. |
| Power input | Compressor and condenser-fan input at the stated rating point. |
| Efficiency | Full-load COP/EER and a suitable part-load metric under identified test or project conditions. |
| Hydraulics | Design flow, evaporator pressure drop, minimum flow and connection size. |
| Operating limits | Allowed fluid temperature, ambient and flow envelope for the offered model. |
AHRI 550/590 and 551/591 cover performance-rating methods for factory-made vapor-compression water-chilling packages, including air-cooled condensers. Certification is model-specific and is not implied by this page. Ask for the exact standard, rating conditions and certification status in the written offer.
Air-Cooled Screw vs Water-Cooled Screw Chillers
| Project factor | Air-cooled screw chiller | Water-cooled screw chiller |
|---|---|---|
| Heat rejection | Condenser coils and fans reject heat to outdoor air. | Condenser water carries heat to an external rejection system, commonly a cooling tower. |
| Water infrastructure | No condenser-water loop or tower water treatment. | Requires condenser-water pumps, treatment, controls and tower or another suitable heat sink. |
| Weather basis | Capacity and power depend directly on outdoor dry-bulb and airflow. | Performance depends on entering condenser-water conditions and the heat-rejection system. |
| Maintenance focus | Coil cleaning, fan condition and clear airflow paths. | Heat-exchanger cleaning, water quality, pumps and tower maintenance. |
| Plant energy | Include compressor, condenser fans and chilled-fluid pumps. | Include chiller, chilled/condenser pumps and tower fans. |
Air-cooled does not automatically mean more or less economical for every site. Compare installed scope, annual load profile, climate, water cost, maintenance capability and total plant energy.
Full-Load and Part-Load Efficiency
Many process and HVAC systems spend substantial time below peak load. The U.S. Department of Energy’s current chiller purchasing guidance separates full-load-optimized and part-load-optimized applications and requires comparison of both operating modes. That principle matters even when a project is outside U.S. federal procurement.
- Provide the hourly or seasonal load profile if available.
- Confirm the number of refrigeration circuits and capacity-control method in the offered unit.
- Compare efficiency at matching fluid and ambient conditions.
- Include condenser-fan and pump power in operating-cost estimates.
- Check minimum stable load and the control sequence for multiple chillers.
Do not compare a standard-rating IPLV value directly with a project-specific NPLV or a single full-load COP. The metric, standard and rating point must match.
High Ambient, Low Ambient and Installation Conditions
The condenser needs unrestricted outdoor airflow. Hot discharge air recirculating into the coil raises condensing temperature and can reduce capacity or trigger high-pressure protection. The layout should account for walls, screens, adjacent units, prevailing wind and future service access.
- High ambient: state the maximum design dry-bulb and solar/site exposure; request a selection at that condition.
- Low ambient: confirm condenser-fan control, minimum operating ambient and chilled-fluid freeze protection.
- Altitude: lower air density affects heat rejection and must be included in the selection.
- Noise: define the measurement location and project limit before selecting fan options or barriers.
- Coil environment: dust, fibers, salt or corrosive contaminants influence material/coating and cleaning plans.
- Winter shutdown: specify draining, heaters or a suitable inhibited glycol solution according to the site risk.
Process Cooling and HVAC Applications
Air-cooled screw chillers can serve larger continuous or variable loads where condenser-water infrastructure is undesirable. Typical project categories include plastics and rubber processing, chemical production, food and beverage processes, machinery cooling and commercial chilled-water systems. Application suitability is confirmed from actual duty, materials, control tolerance and site conditions—not from an industry label alone.
For lower capacities or modular staging, compare an industrial scroll chiller. For subzero secondary fluids, review the low-temperature chiller selection guide. A packaged industrial chiller system may also include pumps, a buffer tank and controls when those items are defined in the proposal.
Refrigerant and Legacy R22 Planning
GESON can offer new air-cooled screw chiller projects using R454B or R513A where the selected compressor, unit design, fluid conditions, ambient envelope, destination regulations and local service capability permit. Availability and safety provisions are confirmed for the specific model in the written technical proposal.
For legacy GESON R22 equipment, GESON can assess model-dependent spare-parts and refrigerant-related service. This is not an unrestricted promise to supply R22 in every destination. Provide the nameplate, serial number, photos, fault description and site location so parts compatibility, legal constraints and repair-versus-replacement options can be reviewed.
Data Required for an Air-Cooled Screw Chiller Quote
| Required input | Why our engineer needs it |
|---|---|
| Application and heat load | Defines the required duty and operating profile. |
| Entering/leaving fluid temperatures | Sets evaporator duty and compressor lift. |
| Design flow | Allows temperature difference and pressure drop to be checked. |
| Fluid and glycol concentration | Changes heat transfer, viscosity and freeze protection. |
| Maximum/minimum ambient and altitude | Defines condenser selection and operating envelope. |
| Load profile and redundancy | Guides circuit count, staging and standby requirements. |
| Power supply | Voltage, phase and frequency determine electrical design. |
| Destination and installation constraints | Supports refrigerant, documentation, size, sound and access review. |
Air-Cooled Screw Chiller FAQ
Does an air-cooled screw chiller need a cooling tower?
No. Its condenser fans reject heat directly to outdoor air, so it does not need a cooling tower or condenser-water loop. The chilled-fluid side still needs correctly sized pumps, piping, flow protection, insulation and any required buffer volume.
How do I select a 50-ton or 300-ton air-cooled screw chiller?
State the required net capacity together with entering/leaving fluid temperatures, flow, glycol concentration, maximum ambient, altitude and power supply. “50 ton” or “300 ton” alone is insufficient because actual capacity and input power change with the operating conditions.
What is the COP of an air-cooled screw chiller?
COP is cooling capacity divided by input power at a stated operating point. There is no single COP for every air-cooled screw chiller. Compare model-specific full- and part-load data at matching fluid temperatures, flow and outdoor ambient, with fan and pump boundaries identified.
Can an air-cooled screw chiller operate in high ambient temperatures?
It can be selected for high-ambient duty only within the offered model’s operating envelope. Provide the maximum dry-bulb temperature, altitude and installation layout. The proposal should show capacity and input power at that condition rather than relying on standard-rating data alone.
Can an air-cooled screw chiller use glycol?
Yes, when the evaporator and controls are selected for the specified glycol type, concentration and temperature. Glycol changes heat-transfer properties and pressure drop, so the quotation must state the mixture, flow and rated conditions.
What maintenance does an air-cooled screw chiller require?
Planned work normally includes condenser-coil inspection and cleaning, fan and electrical checks, fluid quality and flow verification, leak checks by qualified technicians, control/alarm review and maintenance specified for the offered compressor. Access and intervals depend on the site environment and model documentation.
Request a Rated Chiller Selection
Send the application, required load, entering/leaving fluid temperatures, flow, fluid or glycol concentration, maximum ambient, altitude, load profile, power supply and destination country. GESON will review the operating point and define the proposed equipment scope.