Immersion Cooling

What is immersion cooling

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Presenting the best possible performance, energy reduction, density and flexibility

Immersion cooling is an IT cooling practice by which complete servers are immersed in a dielectric, electrically non-conductive fluid that has significantly higher thermal conductivity than air. Heat is removed from the system by circulating liquid in direct contact with hot components, then through water-cooled heat exchangers.

Immersion cooling is particularly effective in managing the heat generated by high-performance processors and GPUs, allowing for better thermal management in densely packed computing systems. Moreover, the ability of the liquid to capture all the IT energy combined with warm water cooling enables solutions ready for heat reuse.

Ultimately, immersion cooling offers energy saving, water saving and space saving.


The benefits of using immersion cooling vs traditional cooling systems

Lower Power usage effectiveness (PUE)

Power Usage Effectiveness (PUE) has been adopted as a major KPI for datacentres. The formula is simple: total energy footprint of the facility / the energy consumed by IT.  

Air cooling (the method traditionally used in datacentres) relies on fans and air circulation to dissipate heat from the IT components, while immersion cooling uses a fluid to directly cool the hardware, providing more efficient heat transfer. When the average global PUE is 1.55 and immersion cooling can reduce that to below 1.1, there’s no better efficiency approach than immersion cooling in today’s market.

important cost savings

Immersion cooling offers high thermal dissipation and can recover all of the heat created. It’s also clean and environmentally friendly. Removing the fans means that all the energy invested in the server is put to work, which adds value to the data, saving over 10% of IT power and essentially removes a failure point.

Decrease in datacentre CAPEX and OPEX. Air cooling requires large amounts of energy to continuously circulate and cool the air, not to mention run the compressors in refrigeration air chillers within the datacentre. Immersion cooling reduces energy consumption by leveraging the high heat capacity of the cooling liquid, resulting in significant energy savings.

enable Huge density computing

Immersion cooling allows for a much higher computing density compared to traditional air-cooling methods. Since the dielectric liquid can dissipate heat more efficiently than air, tanks can be packed more closely together than racks in a smaller space, increasing the amount of compute housed in that area.

increased Reliability

On an IT level, immersing the servers reduces the risk of overheating, thermal stress and oxidation on server components by displacing air from the server components, leading to fewer hardware failures and longer equipment lifetimes. It’s also worth noting that the Asperitas natural convection system is able to function very well on high operating temperatures, high utilisation while being self-managed at the same time. To tackle redundancy, continuous cooling and maintainability can happen concurrently – and this all happens alongside autonomous safety and comprehensive monitoring.

Traditional datacentre cooling vs immersion cooling

Traditional datacenters

  • Limited geographic options (free cooling & water supply)
  • Complex facility
  • HPC requires liquid cooling already
  • increased regulatory challenges

Datacentres using immersion cooling

  • Minimal water useage
  • No constraint on location
  • Improved efficiency anywhere with simple build and minimal costs
  • Waste heat used as an asset
Immersion Cooling infrastructure
The fluid

The fluid used in immersion cooling systems

Asperitas makes use of Shell’s Immersion Cooling S5X hydrocarbon fluid, based on Shell’s Gas-to-Liquid (GTL) technology. The two companies have worked together to provide a safe, fit-for-purpose fluid in which the servers are fully immersed within the Asperitas solution. The fluid itself never leaves the tank - once it's in, it's in.

The single-phase fluid was co-developed with Asperitas and is designed to reduce energy costs and emissions through its high cooling efficiency, excellent flow behaviour as well as its thermodynamic properties. The system uses natural convection to transfer heat from the IT equipment via Shell’s immersion fluid to the water-cooled heat exchangers, making it much more energy efficient than using fans to transfer the heat.

We are very pleased with the technology from Asperitas using the Shell S5X immersion cooling fluid. The integrated cooling solution is helping us deliver very high-end Intel CPU and GPU processing power to our Research and Development departments whilst also reducing our energy consumption within the datacentre itself. Continued adoption of immersion cooling within the landscape is key for our partners and customers sustainability goals.””

David Baldwin
HPC Program Manager at Shell

Frequently asked questions about the fluid

What is single-phase Immersion Cooling?

Single-phase immersion cooling, as the name suggests, is where the coolant stays in a single (liquid) phase, and does not evaporate. The coolant captures the heat from the immersed components and is circulated through a heat exchanger that transfers the heat to a water loop, which in turn can be cooled with an evaporative/adiabatic cooling tower, dry-cooler (radiator), or an existing chiller plant (not required, but compatible).

What is two-phase Immersion Cooling?

Two-phase immersion cooling is where the coolant is designed to evaporate (change phase from liquid to gas) at lower temperatures, boiling off when it comes in contact with hot components. The evaporated coolant vapor is then condensed back to the liquid state through the use of condenser coils, typically located at the top of a sealed rack.

How is the fluid being circulated in Immersion Cooling systems?

Asperitas is the only immersion cooling provider that has solutions for the full range of datacentre deployments and workloads to deliver cooling through Perpetual Natural Convection (no pumps) and Direct Forced Convection platforms.

Are hydrocarbon-based coolants the same as mineral oil?

Hydrocarbon fluids used for single-phase immersion cooling are typically synthetic fluids, which should not be confused with mineral oil. Mineral oils can often have imperfections, impurities, and limit material compatibility. Synthetic fluids, on the other hand, are manufactured at a molecular level which results in an inherently stable product that offers superior performance and material compatibility.

They are clear, odorless, non-toxic fluids that are readily used in domestic products such as cosmetics and other household products, which have well-established material handling practices, minimal regulations, and no direct GWP (Global Warming Potential). The latter is known challenge with fluorocarbons.

Asperitas exclusively works with superior synthetic immersion fluids which are fully tested and optimized for immersion cooling.

Do you need to replace the fluid?

The single-phase fluid used by Asperitas does not evaporate under normal operating conditions and does not need to be topped up. Regular lab tests are performed on the coolants to test for any variance in critical properties over time. To date, all commercial deployments have been running efficiently and reliably, with no degradation in the fluid’s performance.

Are there additional risks, like fire hazard?

The fluid used by Asperitas has a very low flammability rate and does not readily ignite. The US National Fire Prevention Association (NFPA) 704 diamond rates such coolants as 0-1-0 substances. This means that it poses no health hazard, has a high flash point, and is stable even under fire exposure conditions.

The fluid is pure, stable, non-toxic, non-volatile, bio-degradable and recyclable

How it works

How PNC immersion cooling works

In an immersion cooling system, electronic components are placed into a tank filled with a dielectric fluid, which is a non-conductive liquid that does not conduct electricity. The fluid directly contacts the hot components, absorbing the heat they generate. The heated fluid then circulates away from the components and can be passed through a heat exchanger to dissipate the heat into the surrounding environment or recirculated through a cooling system.

Servers need to be cooled
Servers are placed vertically in fluid in the cooling tank
The fluid is heated by the servers
The warmed fluid rises up the tank through servers and out of the top, creating a top layer of warmed fluid
Top layer fluid comes into contact with heat exchangers
Top layer fluid is cooled by heat exchangers
Cooled fluid travels down the heat exchanger (because of the density)
Cooled fluid begins journey again
Cooled fluid begins journey again
Cooled fluid begins journey again

IT availability and partnerships


To ensure access to compatible immersion cooling hardware, Asperitas has partnered with a wide range of industry leaders. Each of our partners is contributing to the success of Immersed Computing®.

Dell Technologies
UNICOM Engineering
Kiturami Bumyang Air Conditioning Co. Ltd
Giga Computing
Kingston Technology
Penguin Computing
Unica Datacenters

Frequently asked questions about IT

Can I service IT hardware which has been immersed?

Yes, you can. Components can be easily replaced using the Asperitas Service Trolley. The horizontal, open rack design allows easy access to each immersed server individually.

Can I immerse storage and networking or is it just servers?

While immersion cooling is commonly associated with servers, it can be extended to other components such as storage and networking equipment.

Can I immerse the cables?

Yes, the cables can be immersed in accordance with material compatibility requirements.

How about warranty on hardware and components?

Several OEMs offer standard warranty and Asperitas is working closely with system integrators and OEMs to offer suitable warranty models.

Can I use standard hardware?

Standard hardware - hardware originally designed for air cooling, can indeed be optimized for immersion. However nowadays, many server providers are offering more than 70 different servers for immersion specifically that are ready to go. Asperitas is working closely with leading OEMs to provide immersion ready servers to ensure the best possible performance for your IT.

Facility requirements

Facility requirements and optimal setups

Immersion cooling solutions allows the datacentre to go to places potentially inaccessible before - whether it is an expansion of the existing datacentre space, inside an office building or closer to the edge of the network like a rural area. This opens up possibilities to integrate IT into other industrial processes to address the global need for energy efficiency.

A single water loop can be shared across multiple liquid cooling modules and the modules can be placed back-to-back and side-to-side. Since there is no air required for the system to operate, large rows of interconnected systems can be placed in relatively small spaces.

Flexible Location

Each system requires only power, access to a water loop and data connectivity to operate. Combined with its silent workings, these limited requirements enable high flexibility in deployment sites and scenarios for immersion cooling, inside and outside the datacentre.The physical location of the datacentre becomes less challenging with

Easy setup

  • Raised floors and isle separation schemes are no longer required.
  • The emergency no-break power systems can be minimised to lower power requirements for IT and cooling systems.
  • Compared to an average air cooled cloud datacentre, immersion cooling can facilitate 5-10 times as much density.
  • The minimised cooling requirements results in smaller, simplified and cheaper datacentre cooling installations.
Immersion tanks multiple deployment

Frequently asked questions about the setup

Can I take Immersion Cooling to my colocation provider?

Many colocation providers are ready for liquid cooling solutions including immersion, which makes sense because they can facilitate high density customers in a simple and cost efficient way. Asperitas is working with several colocation providers to ensure the immersion adoption process is smooth.

Does immersion require a raised floor?

Immersion cooling eliminates the need for raised floors entirely, but if you already have a raised-floor infrastructure there is no need to remove it, and likely no need to reinforce or modify it in any way.

What about floor space utilization?

Immersion cooling produces significant space savings: no hot/cold aisles or high ceilings are required, neither is room for air circulation. Immersion Cooling does not need the height you will see in traditional datacenters, in fact in most cases the same data hall can be designed to have two levels with immersion cooling instead of just one traditional level. With immersion you will achieve a higher performance and more IT power per unit area.

I need to comply with several standards and certifications, is Immersion Cooling compliant?

Asperitas systems are compliant to the most common system certifications, but you can check your specific provider for details or for tailored certifications for your application.

Do I need to train my staff for working with Immersion Cooling?

For new users of immersion cooling, servicing and maintaining the system is simply different to air-cooled systems. It is not more complicated. The right approach is to train staff and Asperitas offesr this service.

Get started

Next steps, how to get started with immersion cooling

It all starts with planning and road mapping. Setting sustainability objectives is one thing, but it’s important to also identify your performance requirements for the next few years. Also ask yourself, where do you see your workloads being facilitated? The next step is to share the project brief with us. Then it's a matter of gaining experience via remote testing and on-site experiences, starting with piloting and then building your scale-out plan.

Ready to get started?

Book your free consultation now. Let us guide you to a more sustainable and efficient datacentre..

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Immersion cooling multiple deployment

Glossary of common terms

glossary terms
Specialized computer or software system designed to respond to requests from client devices, providing services, data, or resources over a network. Servers play a central role in facilitating communication, hosting websites, running applications, and managing data storage in various computing environments. Also referred to as chassis, node or sled. Generally, the server = system, a node or blade or sled is one of multiple servers in a single chassis
Natural convection
Heat transfer process that occurs due to the movement of fluids caused by density variations resulting from temperature differences within the fluid. Unlike forced convection, which involves the use of external means such as fans or pumps to move the fluid, natural convection relies on buoyancy forces created by temperature gradients.
Central Processing Unit. It is the primary component of a computer that performs most of the processing tasks.
Graphics Processing Unit. It is a specialized electronic circuit designed to accelerate the processing of images and videos on a computer.
Thermal management
Thermal management refers to the strategies and technologies implemented to control and optimize the temperature of electronic devices, systems, or components.
Thermal stress
Mechanical stress or strain that occurs in a material or object as a result of temperature changes.
Chemical reaction in which a substance loses electrons.
Dielectric fluid
Type of insulating liquid that does not conduct electricity.
Hydrocarbon fluid
Liquid composed primarily of hydrocarbons—molecules made up of hydrogen and carbon atoms. Commonly used in different industrial applications due to their desirable properties, such as low toxicity and high energy content.
Single-phase fluid
Substance that exists in a single state, either as a liquid or a gas, without undergoing a phase change.
Two-phase fluid
Substance that exists simultaneously in two distinct states of matter within the same system.
Heat exchanger
Often referred to as a HEX, the heat exchanger is designed to transfer heat between two or more fluids, or between a fluid and a solid surface, in a controlled manner

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