Industrial cooling systems often need to maintain stable temperatures across multiple production areas, equipment groups, or processing stages. In many facilities, sending refrigerant directly to every cooling point is not the most practical arrangement. A secondary cooling loop using glycol can provide a more flexible way to distribute cooling throughout the plant.
In this type of system, the refrigeration unit first removes heat from a glycol solution. The chilled glycol is then circulated through heat exchangers, process equipment, storage areas, or air-handling units.
The refrigeration compressor remains at the center of this process. Its performance affects cooling capacity, operating stability, energy consumption, and the ability of the system to respond to changing production loads.
For industrial glycol refrigeration units, an open-drive screw compressor can be a suitable choice when the system requires continuous operation, reliable mechanical construction, and compatibility with different refrigerants.
Why Glycol Is Used as a Secondary Coolant
Glycol systems are commonly used when cooling needs to be distributed over a relatively large industrial facility.
Instead of circulating the primary refrigerant throughout the entire plant, the refrigeration system cools a mixture of glycol and water in a central chiller.
The chilled solution is then pumped through the facility.
The basic process is:
Refrigerant Circuit → Heat Exchanger → Chilled Glycol → Process Equipment → Return to Chiller
This arrangement creates a clear separation between the primary refrigeration circuit and the areas receiving cooling.
Glycol can be useful in applications such as:
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Breweries
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Food processing plants
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Beverage production
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Cold storage facilities
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Industrial process cooling
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Fermentation systems
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Chemical processing
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Temperature-controlled production equipment
The exact glycol concentration depends on the required operating temperature and system design.
A higher glycol concentration can provide greater freeze protection, but it also affects viscosity, heat transfer, and pumping requirements. Therefore, the secondary loop needs to be designed as a complete hydraulic and thermal system rather than simply selecting a coolant and circulating it through the plant.
The Compressor Is the Core of the Refrigeration Circuit
A glycol chiller depends on several major components working together.
The compressor raises the pressure and temperature of the refrigerant vapor before it moves toward the condenser. After heat rejection and expansion, the refrigerant returns to the evaporator or chiller heat exchanger to absorb heat from the glycol circuit.
This means compressor operation has a direct relationship with the overall cooling process.
For industrial applications, compressor selection needs to account for more than nominal refrigeration capacity.
Engineers may also evaluate:
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Required evaporation temperature
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Condensing temperature
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Refrigerant type
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Cooling capacity
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Operating hours
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Part-load conditions
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Motor arrangement
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Lubrication system
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Maintenance requirements
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Site ambient conditions
A compressor that performs well under one operating condition may not provide the same efficiency under another.
Why Screw Compressors Are Used for Industrial Cooling
Industrial refrigeration systems often operate for long periods rather than only during occasional peak demand.
Screw compressors are widely used in this type of environment because their continuous compression principle is well suited to larger refrigeration loads.
Compared with reciprocating compressors, screw compressors use rotating male and female rotors to compress refrigerant gas.
This allows the compression process to occur continuously.
For a glycol chiller serving a production facility, continuous compression can provide a stable cooling source for the secondary loop.
Screw compressor systems can also be designed for variable operating conditions, allowing refrigeration capacity to be adjusted according to actual plant demand.
This is important because industrial cooling loads rarely remain constant throughout an entire day.
A brewery, for example, may have different cooling requirements during fermentation, cleaning, packaging, and periods of low production.
Open-Drive Design Offers Service Flexibility
An open-drive screw compressor separates the compressor mechanism from the motor.
Unlike a hermetic compressor, where the motor and compressor are enclosed in a common housing, an open-drive configuration provides external access to the drive arrangement.
This architecture can be attractive for industrial refrigeration projects where long service life and maintainability are important considerations.
Maintenance teams can inspect and service the drive system without treating the entire compressor as a sealed assembly.
Open-drive equipment can also provide greater flexibility when selecting or replacing the prime mover, depending on the compressor configuration and system requirements.
For facilities where refrigeration equipment represents a critical production asset, accessibility can have a direct impact on maintenance planning.
Refrigerant Selection Is Part of the System Design
Modern industrial refrigeration projects are increasingly considering refrigerants with lower environmental impact and suitable thermodynamic performance.
Depending on the compressor and system configuration, industrial screw refrigeration equipment can support refrigerants such as:
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Ammonia (R717)
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Propane (R290)
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Other hydrocarbons
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CO₂ in suitable system architectures
The refrigerant cannot be selected independently of the compressor.
The compressor, oil system, seals, valves, heat exchangers, controls, and safety equipment all need to be compatible with the selected refrigerant.
Natural refrigerants can provide important advantages, but they also require appropriate engineering and safety measures.
For example, ammonia systems require careful consideration of toxicity and plant safety. Hydrocarbon refrigerants such as propane are flammable and therefore require suitable equipment design, ventilation, electrical classification, and installation procedures.
The refrigeration contractor should evaluate the complete system before selecting the refrigerant and compressor combination.
Glycol Chillers Can Improve Cooling Distribution
One of the main advantages of a secondary glycol system is the ability to distribute cooling through a separate liquid circuit.
A central refrigeration plant can serve multiple cooling points through pumps and insulated piping.
This can simplify the overall plant architecture in applications where several pieces of equipment require cooling.
For example, a brewery may use chilled glycol for fermentation tanks, process heat exchangers, and other temperature-sensitive equipment.
The refrigeration circuit remains concentrated in the chiller plant, while the secondary coolant travels to the production area.
This separation can also make temperature control easier in facilities with multiple process zones.
Each cooling point can be designed around its own heat exchanger, valve arrangement, and control strategy.
Temperature Control Is Critical in Process Cooling
Industrial refrigeration is not simply about reaching a low temperature.
The system must maintain the required temperature within an acceptable range while production conditions change.
In a glycol chiller, several variables influence the final process temperature:
Compressor Capacity + Glycol Flow + Glycol Concentration + Heat Exchanger Performance + Process Load
If the compressor is oversized or undersized for the application, the system may operate inefficiently.
If glycol flow is too low, heat transfer may become insufficient.
If the glycol concentration is inappropriate, pumping requirements and heat transfer characteristics may change.
This is why the compressor should be selected after the complete cooling load has been established.
Variable Production Loads Require Capacity Control
Industrial facilities rarely operate at one fixed cooling load.
A production line may operate at full capacity during one shift and much lower capacity during another.
Running a large compressor continuously at conditions far below its optimal operating point can reduce overall system efficiency.
Capacity control can help match compressor output to the actual refrigeration requirement.
Depending on the compressor and system architecture, capacity regulation may involve mechanisms such as slide-valve control, variable-speed operation, or staged compressor operation.
For larger installations, multiple compressors can also be arranged in parallel.
This allows the refrigeration plant to respond more effectively to changing demand.
Heat Exchanger Design Affects Glycol System Performance
The compressor is only one part of the refrigeration system.
The heat exchanger between the refrigerant and glycol is equally important because it determines how effectively heat moves between the two circuits.
The design should consider:
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Glycol flow rate
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Refrigerant evaporation temperature
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Required leaving glycol temperature
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Heat transfer surface area
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Pressure drop
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Glycol concentration
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Process heat load
A larger temperature difference may reduce heat exchanger size, but it can also influence compressor efficiency.
Engineers therefore need to balance heat exchanger investment against operating performance.
The target should be stable cooling with reasonable energy consumption rather than simply achieving the lowest possible glycol temperature.
Energy Efficiency Depends on the Whole Refrigeration Plant
Compressor efficiency receives considerable attention, but the actual energy consumption of a glycol refrigeration system also depends on pumps, fans, condensers, controls, and heat exchangers.
For example, excessive pressure drop in the glycol circuit can increase pump energy consumption.
Poor insulation can increase heat gain between the chiller and production equipment.
A condenser operating at unnecessarily high pressure can increase compressor power consumption.
The system should therefore be evaluated as a complete energy chain.
Important operating parameters may include:
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Compressor power
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Refrigeration capacity
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Coefficient of performance
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Condensing temperature
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Evaporation temperature
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Glycol supply temperature
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Glycol return temperature
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Pump power
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Cooling-water or condenser-air conditions
Monitoring these values over time can also help identify changes in system performance.
Maintenance Should Focus on the Complete Compressor System
Industrial screw compressors require planned maintenance to remain reliable over long operating periods.
Maintenance programs commonly include inspection of:
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Lubricating oil
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Oil filters
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Bearings
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Rotor condition
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Shaft seals
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Drive coupling
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Refrigerant circuit
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Control sensors
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Safety devices
The exact maintenance schedule depends on compressor design, operating hours, refrigerant, oil type, and manufacturer requirements.
Oil condition deserves particular attention in screw compressor systems because lubrication affects bearings, rotors, sealing, and heat management.
Unusual vibration, temperature changes, oil pressure abnormalities, or changes in compressor power consumption may indicate that further inspection is required.
Where an SRM-26 Class Screw Compressor Fits
The SRM-26 open-drive single-stage screw compressor is associated with industrial refrigeration applications where a robust screw compression platform is required.
Its design uses i-profile rotors with a 5/7 rotor configuration, along with an open-drive architecture intended for industrial service.
The compressor can be applied with refrigerants including ammonia and selected natural refrigerants, depending on the final system configuration.
For a glycol refrigeration unit, the compressor does not circulate glycol directly. Instead, it operates within the primary refrigerant circuit that removes heat from the glycol through the chiller heat exchanger.
This distinction is important when evaluating equipment.
The compressor should be selected according to the primary refrigeration conditions, while the glycol circuit should be designed according to the required secondary cooling load.
The two systems need to be matched through the evaporator or heat exchanger capacity.
What Should Buyers Check Before Selecting a Compressor?
Industrial refrigeration equipment represents a long-term investment, so purchasing decisions should be based on operating conditions rather than compressor model names alone.
Before selecting an open-drive screw compressor, buyers should provide information such as:
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Required cooling capacity
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Refrigerant
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Evaporation temperature
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Condensing temperature
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Glycol supply temperature
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Glycol return temperature
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Expected operating hours
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Cooling load profile
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Installation environment
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Power supply
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Required redundancy
The supplier can then evaluate whether the compressor is appropriate for the intended refrigeration circuit.
For a new glycol chiller project, the compressor should ideally be selected together with the condenser, evaporator, oil system, controls, and secondary coolant circuit.
A glycol refrigeration system is more than a compressor connected to a cooling tank. It is a coordinated system in which the primary refrigerant circuit and secondary glycol loop must operate together.
The compressor provides the mechanical work required to remove heat, while the glycol circuit distributes that cooling to the production process.
Open-drive screw compressors can be particularly useful for industrial installations where continuous operation, service accessibility, and flexible refrigerant selection are important.
The SRM-26 platform represents one option for industrial refrigeration applications involving glycol chillers and secondary cooling systems. Final equipment selection should always be based on the required refrigeration capacity, refrigerant, evaporation and condensing conditions, glycol temperatures, operating profile, and complete system design.
For breweries, food processing plants, process cooling facilities, and other industrial users, a properly engineered combination of screw compressor, heat exchanger, glycol circuit, and control system can provide stable cooling while keeping the refrigeration plant adaptable to changing production requirements.
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