The critical role of glycol in data centre primary cooling infrastructure

As data centre cooling architectures continue to evolve, the role of glycol is becoming increasingly strategic. No longer limited to freeze protection, glycol now directly impacts energy efficiency, system performance, and long-term reliability. This is particularly true as modern designs incorporate more ambient-exposed infrastructure, where fluid selection becomes a critical determinant of overall system behaviour.

In today’s architectures, glycol is essential within primary cooling infrastructure exposed to ambient conditions, where freeze risk, uptime, and energy performance must all be carefully balanced.

These areas include:

• Air-cooled and hybrid chiller systems
• Dry coolers and heat rejection equipment
• Economiser / free cooling circuits
• External pipework and distribution systems
• Primary/Facility Loops

As data centres continue to adopt air-cooled and economised designs, a growing proportion of cooling infrastructure operates outside tightly controlled environments. In these conditions, glycol becomes a core enabler of reliable, year-round operation.

Why glycol is critical in primary cooling infrastructure

Any part of the cooling system exposed to low ambient temperatures is at risk of freezing. Without appropriate fluid protection, this can result in:

• Ice formation in heat exchangers
• Cracked pipework and mechanical failure
• Loss of cooling capacity
• Unplanned downtime

Even short sections of exposed pipework can become single points of failure.

For operators, glycol is therefore not just a protective measure — it is a critical component of system resilience and uptime assurance.

The real challenge: performance vs safety

While glycol is essential, fluid selection has a direct impact on energy efficiency and system performance.

Traditionally, operators have had to balance performance against safety:

Ethylene Glycol (EG) — High Performance, Higher Risk

• Excellent heat transfer and low viscosity
• Supports efficient pumping and strong system performance

However:

• Toxic to humans and harmful to the environment
• Less suitable for data centres due to safety, handling, and regulatory considerations

Propylene Glycol (PG) — Safer, but Less Efficient

• Low toxicity and widely accepted

But:

• Higher viscosity → increased pumping energy
• Lower thermal conductivity → reduced heat transfer efficiency
• Negative impact on COP and PUE

At scale, these limitations translate directly into higher energy consumption and operating cost.

Eliminating the trade-off: Castrol ON Primary Fluid DTX

Castrol On Primary Cooling Fluid DTX has been engineered to remove this compromise.

It delivers:

• The thermal and flow performance of ethylene glycol
• The low-toxicity profile of propylene glycol

Proven Performance Gains vs Propylene Glycol

• 10% increase in COP
• Comparable reductions in energy consumption and carbon emissions
• Lower viscosity → reduced pumping energy
• Improved heat transfer → enhanced PUE performance

In new system designs, this performance can also enable:

• Smaller chillers and pumps
• Reduced pipework sizing
• Lower capital expenditure

Designed for modern data centre cooling systems

Castrol On Primary Cooling Fluid DTX is specifically developed for demanding cooling environments, offering:

• Resistance to oxidation, thermal degradation, and biological contamination
• Optimised thermodynamic and hydrodynamic performance
• Compatibility with nanoparticles and advanced additives
• Low toxicity and biodegradability
• Full compatibility with system materials
• Potential for reuse or upcycling at end of life

DTX is already proven in highly demanding applications including, food and beverage process cooling, medical devices used in surgery, and advanced aerospace cooling systems.