Glycol (either ethylene or propylene) serves as a liquid cooling agent in many industrial and commercial applications. Unlike typical refrigerant gases (R-134a, R-410A, R-404A, etc.), it does not evaporate to transition between phases; rather, it remains in a liquid state, absorbing and transporting heat throughout the system.
When glycol in chillers is employed, a primary refrigerant (gas) typically cools the glycol via a heat exchanger. The chilled glycol is then circulated through an evaporator or coils to reduce the temperature of air or products. Since the fluid stays in liquid form, it continuously removes heat without undergoing compression like conventional refrigerants.
Advantages of This Cooling Medium
Opting for glycol as a secondary cooling fluid in a chiller setup, instead of using direct-expansion refrigerant gas, offers several notable benefits:
- Reduced Refrigerant Charge: By relying on a liquid loop, the total volume of primary refrigerant gas needed is cut down—lowering both costs and environmental impact.
- Greater Safety and Easy Maintenance: In the event of a leak, glycol is non-volatile and poses minimal risk to health or the environment. Cleanup and containment are simpler compared to handling gas leaks.
- Enhanced Temperature Stability: This fluid maintains more consistent temperatures over long distances, particularly in situations where certain refrigerant gases have high glide. Such stability can improve temperature control in the space or product being cooled.
However, integrating this secondary fluid into a standard refrigeration system requires special attention to the evaporator’s configuration and materials.
Adapting a Standard Evaporator
At Sereva, for example, we manufacture evaporators with copper tubes and aluminum fins—ideal for commonly used refrigerants. Yet substituting a gas refrigerant with glycol calls for specific alterations to ensure reliable, efficient performance in the long run.

Potential Issues
- Copper Corrosion: While glycol is very effective at heat transfer, it can corrode copper over time if the system isn’t properly protected. Monitoring fluid chemistry and using corrosion inhibitors are crucial to prevent system deterioration.
- Increased Viscosity: Glycol is denser and more viscous than most refrigerant gases. If you do not account for these properties in the design, flow rates and heat transfer may suffer, leading to subpar system performance.
Evaporator Modifications
- Circuit Redesign: Segmenting the evaporator into multiple, shorter circuits compensate for the higher viscosity of glycol. This helps maintain an adequate flow velocity, improving heat exchange and avoiding fluid stagnation.
- Resistant Materials and Inhibitors: Selecting corrosion-resistant coatings and adding suitable inhibitors in the glycol mix safeguard copper or other sensitive metals. Adjusting pH levels is also vital to prolong equipment life.
- Extra Reinforcements and Protections: Employing additional supports or protective linings can guard against long-term wear. Such measures help minimize maintenance costs and prevent leaks or other mechanical failures.
Benefits of Correct Adaptations
When properly designed for glycol, evaporators can deliver excellent cooling results and maintain stable temperatures. These modifications not only enhance the system’s overall safety but also improve energy efficiency and extend the lifespan of the equipment.
Conclusion
Using glycol in chillers is both feasible and advantageous, provided you make the necessary adjustments. By focusing on corrosion prevention, suitable circuit design, and durable components, you can optimize performance and protect your investment. Early attention to these details sets the stage for efficient operation and long-term reliability.