Data Center Liquid Cooling: How Modern Cooling is Evolving
Data centers are crucial for powering our online lives and businesses in the modern world. However, as data centers grow in power and complexity, traditional air cooling methods are no longer adequate for handling workloads from high-performance computing and artificial intelligence (AI) workloads. The current global AI market is valued at $150.2 billion and growing, illustrating the need for data centers to increase their support for these workloads.
Liquid cooling is emerging as a modern solution to the challenge of data center cooling, providing many advantages, including greater sustainability, lower costs, and the ability to handle greater power densities for more complex workloads. This article will explain what data center liquid cooling is, what sets it apart from air cooling, and the benefits businesses should know about.
What is Data Center Liquid Cooling?
Data center liquid cooling removes heat from IT equipment using liquid. This method is often more efficient compared with air cooling, and enables data centers to operate with higher power densities and at higher temperatures. Data center operators generally use one of two main methods of liquid cooling – direct liquid cooling and immersion liquid cooling.
With direct liquid cooling, the liquid is circulated to the CPU or GPU and then passes through a heat exchanger to remove heat before it is recirculated to the equipment. With immersion liquid cooling, the IT equipment is submerged in a non-conductive liquid that removes the heat. The liquid is later passed through a heat exchanger for cooling. With air to liquid cooling, air passes through the IT equipment into a liquid heat exchanger which removes the heat from the air, returning cool air back into the data center.
The main difference between liquid cooling and air cooling is the efficiency involved in each process. Besides the medium used to move heat from the CPU and other components (air versus liquid). Liquid cooling is typically more efficient, which means components are kept cooler at higher loads using either water or coolants. Water is able to absorb and transfer heat more quickly than air.
Types of Data Center Liquid Cooling
AFCOM’s 2023 State of the Data Center report found that cooling is a main concern for respondents, with 35% saying their current cooling systems aren’t meeting their needs. Improving cooling capacity can come with liquid cooling methods, which can be thought of in a five different ways – immersion, direct-to-chip cooling, two-phase immersion cooling, evaporative cooling, and closed-loop cooling.
With immersion cooling, the IT equipment is submerged in a non-conductive liquid — a coolant that isn’t water. The liquid removes the heat from the hardware and components and then gets cooled in a heat exchanger.
Also known as direct liquid cooling, this method circulates the liquid on the CPU or GPU and then passes the liquid through the heat exchanger to cool it back down before recirculation.
Two-Phase Immersion Cooling
Two-phase immersion cooling takes advantage of a liquid’s phase change to remove heat from IT components.
As electric components begin to heat up, a fluid with a low boiling point and is non-conductive will begin to boil and vaporize. The rising vapor is then cooled and recondensed into a liquid, moving to the bottom of the tank and repeating the reheating cycle. The latent heat of vaporization is used in this method to remove the heat from the IT equipment.
Closely related but not identical is evaporative cooling. This system may use the evaporation of water or a non-conductive liquid to remove heat from a system. The method is more effective in dry climates.
Closed-loop cooling is where coolant is pumped through a closed loop of tubing and pipes, often closely related to direct cooling. This method, used by TierPoint data centers and other third-party providers, is more sustainable than evaporative cooling.
Some of the benefits of liquid cooling data centers are illustrated in the difference between liquid and air cooling, but there are other, forward-thinking advantages businesses should consider when choosing the cooling method for their components.
Liquid has a higher thermal conductivity, which allows it to transfer heat more efficiently than air. This is why liquid cooling can work at higher power densities than air.
The initial setup for a liquid cooling system can be more expensive than air cooling. However, the system can save money long-term through greater efficiency, as well as causing less wear and tear on the hardware.
Fans can only do so much. Liquid cooling keeps hardware and other IT equipment cooler compared to air, reducing the wear on components and increasing their lifespan.
Sustainable and Environmentally Friendly
Data centers are large energy consumers, which carry financial and environmental costs. Liquid cooling systems tend to use less energy compared to air cooling systems, improving the overall sustainability of the data center.
Previously, liquid cooling systems were more complicated to install and maintain, however, they’ve become easier to implement and manage in recent years. Certain systems, such as all-in-one (AIO) systems, are turn-key and designed for straightforward set-up, making liquid cooling significantly more accessible.
Air cooling systems tend to be louder than liquid cooling because of the fans used. While this is more of an environmental difference, a quieter cooling system may be a selling point for some. There are still fans used on liquid cooling radiators, but they run at slower speeds.
A variety of locations can house liquid cooling systems, including edge data centers, mobile data centers, and traditional data centers. They have become a versatile option for businesses looking to cool their systems more sustainably.
As greater demands get placed on data centers, traditional air-cooling systems will not be able to keep up. Liquid cooling systems are the future of data center cooling technology, especially with the rise of AI and GPU systems.
Calculating the Impact of Liquid Cooling Efficiency
If you’re wondering how much more efficient liquid cooling can be compared to an air cooling alternative, the best way to evaluate it is by looking at power usage effectiveness and total usage effectiveness.
Power Usage Effectiveness
Power usage effectiveness (PUE) is calculated by taking the total amount of energy a data center uses and dividing it by the energy used to power necessary IT equipment. The lower the PUE, the more efficient the data center is. For example, an ideal number would be 1.0, but generally, most data centers have higher PUEs because of the energy costs of cooling, lighting, and other overhead expenses. Using a liquid cooling system can bring a PUE down.
Total usage effectiveness (TUE) is an expansion of PUE that looks at the energy efficiency of a data center overall. This includes how much energy is being used by infrastructure, IT equipment, and ancillary equipment. All aspects of the data center are included in this calculation, instead of just IT equipment. Again, the ideal TUE would be 1.0.
Companies looking for a high-density colocation data center that can support AI projects will need to look for facilities that can accommodate higher power densities. Liquid cooling technology is well-equipped to support these greater demands on data centers. For example, TierPoint offers state-of-the-art cabinets tailored to accomodate your high-performance GPU/AI compute needs. These cabinets feature a closed-loop liquid cooling system, offering improved sustainability and efficiency compared to conventional air cooling and evaporative liquid cooling methods. Whether you’re exploring high-density or standard colocation services, or searching for managed cloud options, we’re here to help.
Learn more about our high-density colocation services and schedule a tour today.
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