Liquid Cooling

What Is Liquid Cooling?

Liquid cooling is a method of heat removal that involves the circulation of a liquid, typically a 25% propylene glycol mixture, to transfer heat away from graphics processing units (GPUs). The coolant distribution unit (CDU), is often paired with chillers, air handling units, and cooling towers to ensure proper heat removal for the entire data center.

Compared to air cooling, liquid cooling is a more efficient method of heat transfer because the liquids used have a higher heat capacity and thermal conductivity. For example, water can carry 3,500 times more heat than air and has 24 times higher thermal conductivity.

How Does Liquid Cooling Work?

Liquid cooling systems circulate a coolant through a network of pipes, coils, or blocks that come into direct contact with GPUs. The liquid absorbs heat and is then pumped to a heat exchanger (like a radiator or cooling tower) where the heat is dissipated. The cooled liquid then returns to continue the cycle.

What Liquid Is Used in Liquid Cooling?

Water is commonly used for liquid cooling because it's often readily available and inexpensive. Distilled or deionized water is recommended to reduce the risk of mineral buildup or corrosion. Ethylene glycol and propylene glycol are common additives to water in liquid cooling systems because they can improve freeze protection and corrosion inhibition.

When water is not readily available, as in drier climates or drought-stricken regions, other liquids can be used. Dielectric fluids are useful for immersion cooling when electrical parts are in direct contact with the liquid and are often used for liquid cooling in data centers. Some refrigerants are also compatible with immersion cooling. Talk to your local Trane expert to learn which liquid will fit your needs best.

Applications of Liquid Cooling

Liquid cooling is the most efficient choice for data centers, especially when faced with high heat loads, space constraints, or a need for quieter operation. Coolant distribution units work well amongst densely packed servers, where air cooling struggles to keep up with heat generation.

Standard commercial cooling equipment is not sufficient for hyperscale or colocation data centers. Liquid cooling works best in these facilities due to its superior heat absorption and dissipation, which enables higher server densities while improving energy efficiency. By ensuring equipment stays within safe temperature thresholds, liquid cooling helps extend its lifespan, lowering operational costs over the long term.

Advantages of Liquid Cooling

• Efficient heat transfer: Liquids have a higher thermal capacity than air, making them more effective at absorbing and transferring heat.
• Energy efficiency: Liquid-cooled systems, particularly paired with water-cooled chillers, can be more energy-efficient than air-cooled systems, leading to lower operating costs.
• Quieter operation: These systems often operate more quietly than air-cooled systems that rely on noisy fans.
• Precise temperature control: Thermostats and other components allow for precise and constant temperature regulation.
• Increased lifespan: Efficient heat transfer can extend the lifespan of equipment.

Disadvantages of Liquid Cooling

• Higher initial cost: Liquid cooling systems can have higher upfront costs due to the need for specialized components like pumps, heat exchangers, and cooling towers.
• Complexity: Installation and maintenance can be more complex compared to air-cooled systems.
• Leak potential: Although newer technologies have minimized the risk, leaks can still occur and cause damage to equipment. Regular maintenance can help mitigate the potential.
• Water requirements: Systems utilizing water-cooled condensers require a reliable water source, making them less suitable for drought-prone areas.

Resources for Liquid Cooling

• Go with the Flow: Is It Time Yet for Liquid Cooling?
• Case study: Cyxtera Data Center: Energy-Efficient Cooling and Cost Savings
• Case study: Enhanced Safety and Cost-Saving: Chiller Upgrade at Ron Gorr Memorial Arena
• Case study: King's Daughters Medical Center

Trane Commercial HVAC offers liquid cooling options, including water-cooled chillers and coolant distribution units for a wide range of applications. Contact your local Trane representative to discuss the liquid cooling system that will best fit your organization's requirements.