Liquid Cooling

Is Liquid Immersion cooling a good idea?

Is liquid cooling the future of data center? 
Data center operators are evaluating infrastructure cooling options in liquid form in order to provide new, more efficient solutions to the new needs linked to the digitalization of our world.

Estimated at $3.14 billion in 2022, the worldwide liquid cooling market in data centers is expected to reach $31.7 billion in 2032, with annual growth of 25.8%.

Currently, data centers support rack power requirements in excess of 20 kilowatts (kW), but the market is heading in the short to medium term towards 50 kW or more. Next-generation central processing units (CPUs) and graphics processing units (GPUs) have higher thermal density properties than previous-generation architectures. Additionally, server manufacturers are packing more CPUs and GPUs into each rack to meet the accelerating demand for high-performance computing and new and upcoming applications of artificial intelligence.

Air cooling systems, the most commonly used in data centers today, are now showing their limits. They simply cannot cool high-density racks effectively and sustainably.

Long proven for mainframe computers, liquid cooling is expanding to protect rack-mounted servers in data centers around the world.

Let’s first see what liquid cooling is, what are the different technologies used for liquid cooling and what are its current advantages and

Disadvantages : 
What is liquid cooling and what are its benefits?
As early as 1985, supercomputers were immersed in liquid for more efficient cooling. Today, the possibility of cooling CPUs and GPUs using liquid has made its way into many data centers.

Water and other liquids used are much more efficient than air at transferring heat and can help solve some of the problems with air-cooled systems, especially as compute densities increase.

The main liquid cooling technologies
A liquid cooling technology that is gaining popularity is direct plate cooling. In this configuration, a cold plate is placed directly next to a component, such as a CPU, GPU, or memory card. Small tubes are connected to the plate to bring cold water and evacuate hot water. The hot water is then cooled so that it can be reused and circulated back to the cooling device.

A similar concept can be applied at the rack or server level. Water or another type of coolant circulates in a closed circuit system to carry out the heat exchange. Although the exact process varies from solution to solution, this solution generally uses a contained coolant, a heat exchanger to dissipate heat, and a mechanism to lower the temperature of the coolant as it circulates. For example, a heat exchanger can be mounted at the rear of the rack with fans on the opposite side to circulate air and dissipate heat. Another system thus routes the coolant underground to provide geothermal cooling.

Immersion cooling is a newer technology that is making great strides over time. With this approach, all internal components of the server are immersed in a non-conductive dialectical fluid. The components and fluid are then enclosed in a sealed container to prevent leakage. In this way, the heat from the components is transferred to the coolant which is circulated and cooled to continuously dissipate the heat.

The advantages of liquid cooling
Liquid cooling-based technologies take advantage of the superior heat transfer properties of water or other fluids used to provide efficient and cost-effective cooling of high-density racks. This technology can be up to 3,000 times more efficient than using air.

Because liquid cooling conducts heat better than air, it can more effectively handle increasing data center densities, accommodating compute-intensive applications and arrays.

Additionally, liquid cooling significantly reduces power consumption and uses less water than many air-cooling systems, which can result in lower operating costs and a lower data center carbon footprint.

Finally, liquid cooling is also less bulky and less noisy.

Disadvantages of liquid cooling 
Despite all the advantages mentioned above, liquid cooling has a number of disadvantages. In addition to a higher capital cost, this technology requires data center administrators to learn new skills and adopt a new management framework, which can be a lot of work.

It may also be necessary to recruit additional staff or consultants who are familiar with this new technology and thus reduce the financial advantage in terms of return on investment. Additionally, the liquid cooling market is still maturing with a wide range of technologies resulting in proprietary products and risk of vendor lock-in.

What factors to consider when choosing between an air-cooled and liquid-cooled system
Companies building new data centers or retrofitting existing data centers may wonder if it's the right time to deploy liquid cooling now. Air cooling on the other hand is a safe bet that has already done time and time again its proofs.

Here are a number of factors to consider in making the best choice:

Cost will no doubt be one of the deciding factors, but achieving true total cost of ownership can be a complex process. Although liquid cooling comes with a higher capital cost, its greater efficiency can translate into lower operating costs, especially as densities increase. Additionally, liquid cooling uses less energy and consumes less water, which can be especially important in regions where water is scarce. On the other hand, the risk of vendor lock-in can impact the long-term total cost of ownership and maintenance.

The computers themselves should also be considered when evaluating the systems and total cost. Liquid cooling helps support higher compute densities while reducing the carbon footprint of the data center, resulting in better space utilization and lower costs.

Ease of installation & maintenance
Another important consideration is the deployment and maintenance of the liquid cooling system. With air cooling, equipment operation and component replacement are usually straightforward. That's not to say that air cooling doesn't come with its own set of challenges, such as ongoing water treatment or mechanical maintenance, but it's a known entity with a long history to take all of them into consideration. these elements.

Liquid cooling represents a new mindset and a new way of working. IT teams and data centers will face a steep learning curve, and in some cases may be dependent on a vendor for routine maintenance. For example, what if IT needs to replace the memory card in a server that uses immersion cooling technology? When analyzing costs, data center operators should evaluate all the implications of deploying and maintaining a cooling system.

Some data centers do not support high compute processing density, so a move to liquid cooling may not be justified. That said, compute densities are only going to increase in the years to come. Data centers are striving to make better use of usable floor space, and IT departments are consolidating workloads to improve efficiency. At some point, liquid cooling might become the only viable option, but that doesn't mean data centers have to make the switch right away.

Other efficiency considerations can play a role in choosing liquid cooling over air cooling. For example, a data center operator may be moving towards greener practices and want to adopt technologies such as liquid cooling which uses fewer resources and is much quieter.

The location of the data center can also be an important selection criterion. A data center located near the Arctic may use an abundance of cold air, while a data center located in hot areas will have difficulty maintaining air cooling systems over the long term.

A data center located in a crowded urban environment may need to increase the compute density of its racks to maximize floor space. Local regulations, tax benefits or other similar issues may also play a role.

Today, with air cooling, companies know what they're getting into, but its long-term usefulness might be limited. Companies that don't need to rush to make a decision might want to give liquid cooling more time to mature.

One thing is certain, this technology should continue to grow and mature over time, whether to meet the needs of more efficient cooling systems or to reduce the carbon footprint of their data centers.