Liquid cooling is an approach to cooling IT equipment seen in data centers, High Performance Computing, communication equipment and other enterprise computing. Liquid cooling utilizes circulating liquids, such as dielectric fluids, to efficiently cool the electronic components. This additional efficiency can be used to transform data center sustainability by reducing the power demand of cooling through removal of the need for extensive air handling and refrigeration equipment. This additional cooling efficiency is also a strong candidate for enabling higher performance chips used in High Performance Computing, Artificial Intelligence and Machine Learning, and cryptocurrency mining among many others.

Liquid cooling works by circulating a coolant liquid, typically water or a special fluid, in close proximity to heat-generating components like CPUs. The coolant absorbs the heat and is then pumped away to a heat exchanger, where the heat is dissipated, and the cooled liquid is recirculated.

Source: “Water Cooling”, TechTarget.

Liquid cooling solutions are swiftly becoming a vital necessity not just in data centers but also in the broader spectrum of communications and High Performance Computing infrastructure. In these environments, traditional air-cooling methods are increasingly inadequate due to the intense heat generated by the latest, high-density electronic components. These components, found in everything from server farms to telecommunications equipment, are more powerful than ever, leading to a substantial increase in heat production. This heat, if not managed effectively, can lead to reduced efficiency, increased risk of component failure, and higher operational costs. Liquid cooling, with its superior heat transfer capabilities, serves as an effective solution. It directly cools components using fluids that are much more efficient at heat absorption and dissipation compared to air. This direct and efficient cooling allows for more densely packed and powerful components, leading to smaller, more efficient, and potentially less costly setups.

Beyond its technical benefits, liquid cooling is increasingly aligned with the global push towards sustainability and environmental responsibility in technology sectors. Traditional cooling methods, particularly in large-scale operations like data centers and telecommunications hubs, are energy-intensive, often relying on massive air conditioning systems and fans. In contrast, liquid cooling systems are inherently more energy efficient and can significantly reduce the carbon footprint of these technological infrastructures. This efficiency is a game changer, not just in reducing operational costs but also in meeting global environmental standards. Moreover, the versatility of liquid cooling opens up new opportunities for infrastructure design and location, including the possibility of setting up in warmer regions or utilizing novel concepts like submerged cooling systems.

Liquid cooling has a positive environmental impact by reducing energy consumption and greenhouse gas emissions. It enables more efficient heat management and can leverage renewable energy sources more effectively. However, it's essential to responsibly manage the coolant materials to minimize any potential negative environmental effects.

Source: "Accelerating Climate Action with Data Center Liquid Cooling", Motivair.

Various liquid cooling solutions include direct-to-chip cooling, where coolant is applied directly to hot components, and immersion cooling, where components are fully immersed in a non-conductive liquid. Each type has specific benefits and applications depending on multiple factors such as whether it is being used for new infrastructure or retrofitting existing infrastructure and the cooling requirements.

Source: "An introduction to liquid cooling in the data center”, Data Center Dynamics.

Dielectric fluids are commonly selected as they do not conduct electricity and can make contact with IT components directly for safety, reliability, and efficiency. These fluids can be categorized into two forms: single-phase fluids and two-phase fluids.

Single-phase fluids collect heat without reaching their boiling point and changing into any other phase of matter. These fluids can be hydrocarbon, fluorine-based materials, and natural or synthetic esters, among other specialty materials. The single-phase fluids typically do not emit volatile materials to the environment. Care should be taken when selecting fluorinated fluids to find low global warming potential materials and be aware of the possibility of PFAS containing chemicals.

Two-phase fluids collect heat and are intended to reach their boiling point to generate a vapor phase. This vapor rises out of the liquid, removing the heat from the system. However, the vapor must be captured in a sealed environment to be cooled, condensed, and returned to circulation. These fluids tend to be fluorine based materials but other fluids can be found. Care should be taken when selecting fluorinated fluids to find low global warming potential materials and be aware of possibility of PFAS containing chemicals.

These fluids are typically installed to circulate and exchange heat with a chilled water or cooling water loop to reject collected heat in the mater best suited for the needs of the location.

Data centers, High-Performance Computing facilities, and industries with intensive computational needs, such as AI and Machine Learning, can benefit significantly from liquid cooling. It provides efficient heat management, enabling higher performance and reliability.

Source: "Exploring Liquid Cooling for Next-Gen Business Applications”, Equinix.

While the initial investment in liquid cooling systems can be higher than traditional air cooling, the long-term savings in energy costs and increased hardware efficiency often result in a favorable return on investment. The exact cost implications depend on the scale and specific technology used and whether the technology is being used for new or existing infrastructure.

Source: “Will high energy prices push operators to direct liquid cooling?”, Uptime Institute.

Liquid cooling is vital for IT infrastructure because it offers superior cooling efficiency compared to traditional air cooling. It can handle higher heat loads, making it ideal for high-density computing environments like data centers. Liquid cooling is more effective in transferring heat and can significantly reduce energy consumption, leading to cost savings and environmental benefits.

Sources: "Liquid Cooling in Data Centers", Data Center Dynamics and “Advantages of Liquid Cooling in Data Center Design, Dell.

The trends indicate a growing adoption of liquid cooling, driven by the increasing heat loads of modern computing systems and the need for energy-efficient cooling solutions. The future outlook is positive, with technological advancements and increasing awareness about sustainability further propelling the adoption of liquid cooling solutions in various sectors.

Source: Global Liquid Cooling for Data Center Market Research Report 2022, Precision Reports.

Standard servers and IT equipment can be used for liquid cooling. However, small modifications are recommended for efficiency.

Off-the-shelf servers tend to have cooling fans installed which are best disabled or removed.

Heat sinks are commonly optimized for heat exchange with air and are best replaced with liquid optimized heat sinks, or in the case of direct-to-chip cooling, replaced with a specialty cold plate. The Thermal-Interface-Material may be incompatible with your selected fluid and an alternative may be needed, such as indium foil.

The servers and auxiliary components should be confirmed to be compatible with your system, such as power and data cables and connectors. The sheathing of these components tend to become brittle or damaged by contact with liquid. Liquid Immersion ready cables are available on the market for use in Liquid Cooling.

Numerous case studies demonstrate the successful implementation of liquid cooling in various settings, from small-scale IT deployments to large data centers. These case studies often highlight significant improvements in energy efficiency, cooling performance, and cost savings.

Sources: “3 Case Studies on Liquid Cooling as best solution”, C&C Technology Group and “Our commitment to climate-conscious data center cooling”, Google.

Liquid cooling contributes to energy efficiency by reducing the energy required for cooling systems, which is a significant portion of a data center's energy consumption. By efficiently managing heat, liquid cooling allows for more sustainable IT operations and aligns with green computing initiatives.

Sources: "Liquid Cooling Systems Help Achieve Sustainability Goals", Electronics Cooling and “Liquid Cooling: The Key to Data Center Sustainability”, LiquidStack.

Safety considerations include ensuring the proper handling and maintenance of cooling fluids, preventing leaks, and using non-conductive coolants to avoid electrical hazards. Regular system inspections and adherence to industry safety standards are crucial for safe operation.

Sources: "Application Considerations for Bringing Liquid Cooling to Air-Cooled Data Centers" , Engineered Systems and “Six things to consider when introducing liquid cooling”, Data Center Dynamics.

To learn more, individuals can access a variety of resources such as industry whitepapers, technical webinars, conferences, and publications from relevant organizations. Many educational institutions and industry groups offer detailed information and training programs on liquid cooling technology.

1. Source: “Liquid Cooling Guidelines for Datacom Equipment Centers, Second Edition” ASHRAE.

2. Source: “Emergence and Expansion of Liquid Cooling in Mainstream Data Centers”, ASHRAE.

3. Source: “Webinar on The Seamless Transition: From Air-Cooled to Liquid Cooling Systems in the Era of Rising Chip Power”, Data Center Frontier.

4. Source: “Understanding Data Center Liquid Cooling Options and Infrastructure Requirements”, Vertiv