Question 1

What is Immersion Cooling?

Accepted Answer

Immersion cooling is an IT cooling practice by which IT components and other electronics, including complete servers, are submerged in a dielectric (electrically non-conductive) fluid that has significantly higher thermal conductivity than air (typically >1,000x the heat capacity by volume). Heat is removed from the system by circulating liquid into direct contact with hot components, then through water cooled heat exchangers.

Question 2

Is Immersion Cooling a new technology?

Accepted Answer

Immersion Cooling is not new. The first reference to the specific use of dielectric fluids being used to cool “computers” is in 1966 by IBM and in 1982, Cray computing registered a patent for high density immersion cooled technology.

Question 3

What is single-phase Immersion Cooling?

Accepted Answer

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).

Question 4

How is single-phase different from two-phase Immersion Cooling?

Accepted Answer

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.

There are primarily two kinds of coolants used for Immersion Cooling: Fluorocarbon-based coolants which are typically used for two-phase applications, and Hydrocarbon-based fluids which are solely used for single-phase Immersion Cooling.

Question 5

What are the pros and cons of two-phase (Fluorocarbon-based) vs. single-phase (Hydrocarbon-based) Immersion Cooling?

Accepted Answer

Upfront costs:  Single-phase Immersion Cooling offers dramatically lower upfront costs due to its simpler overall design, and lower coolant costs.

Energy efficiency: Both forms of Immersion Cooling offer exceptional energy efficiency (pPUE 1.01 – 1.03).

Cooling capacity: Two-phase Immersion Cooling can typically support extreme rack densities, with support up to 250kW in a single rack.

Complexity/usability: Single phase offers an inherently simpler architecture. The lack of evaporation allows for an open bath design, thereby eliminating any inhalation risks or the loss of fluid due to evaporation. The absence of a sealed rack also allows for easier access to servers and hence simpler maintenance SOPs. However, two-phase coolants (fluorocarbon) have the advantage of self-drying hardware that can make material handling easier.

Question 6

How is the fluid being circulated in Immersion Cooling systems?

Accepted Answer

Single-phase immersion requires circulation of the dielectric liquids by pumps or by natural convection flow through integrated or external heat exchangers.

Question 7

Are Hydrocarbon-based coolants the same as mineral oil?

Accepted Answer

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 can be a challenge with Fluorocarbons.

Question 8

What is the difference between single-phase and two-phase coolants?

Accepted Answer

There are primarily two kinds of coolants used for Immersion Cooling: Fluorocarbon-based coolants which are used for two-phase applications, and Hydrocarbon-based fluids which are used for single-phase Immersion Cooling.

Fluorocarbon-based coolants may be used in single-phase applications, but typically offer little benefit at a significantly higher cost and added complexity.

Question 9

Is the fluid expensive?

Accepted Answer

One of the advantages of using Two-phase Immersion Cooling technology is that the fluid being used can last up to 30 years, while, at the same time, offering the most reliable environment for electronic components.

Question 10

Do you need to replace the fluid?

Accepted Answer

Typically the fluid does not need to be replaced through the life of the datacenter (30+ years). Regular lab tests are performed on the coolants to test for any variance in critical properties over time. Commercial deployments dating back to as early as 2010 have been running efficiently and reliably, with no degradation in the coolant’s performance.

Question 11

Are there additional risks, like fire hazard?

Accepted Answer

The fluids used by E3 have no flammability rate and do not ignite.

Question 12

Can I use standard hardware?

Accepted Answer

From a user perspective you are making a tremendous investment in IT hardware, which should be taken seriously and treated with care. Standard hardware that was originally designed for air cooling can be optimized for immersion. This consists of removing components such as fans that have no use in immersion and replacing materials such as thermal paste with materials that have better performance and longevity in fluids.

Question 13

Does it mean all the components are different?

Accepted Answer

No. Standard components – from motherboards, PSUs, memory, storage and CPUs to GPUs can be used.

Question 14

Can I use Immersion Cooling for storage, networking and compute?

Accepted Answer

Yes, you can.

Question 15

Can I service IT hardware which has been immersed?

Accepted Answer

Yes, you can. Components can be replaced, and the horizontal, open rack design allows easy access to each immersed server individually.

Question 16

Can I run Immersion Cooling systems in any datacenter?

Accepted Answer

Yes, you can. Although Immersion Cooling requires a water circuit running to the systems.

Question 17

Can I take Immersion Cooling to my colocation provider?

Accepted Answer

Usually, colocation providers will be happy to facilitate Immersion Cooling, it will allow them to facilitate high density environments without having to make large investments.

Question 18

What about the floor loading?

Accepted Answer

Liquid-Immersion-Cooling systems such as those offered by E3 are designed to be installed on raised floors and concrete slabs alike. And while it may seem obvious, it is important to point out that when talking about floor loading, pressure on the floor is a more important consideration than gross weight alone. Because our racks are horizontal, they help evenly spread weight across their footprint, yielding a floor loading that is often less than that of an air-cooled rack.

Actually, liquid-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.

Question 19

What about floor space utilization?

Accepted Answer

While it is true that an individual horizontal rack has a slightly larger footprint than a vertical rack, when you look at the fully burdened datacenter footprint, 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.

Question 20

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

Accepted Answer

E3 systems are compliant to the most common system certifications, check your specific provider for details or for tailored certifications for your application.

Question 21

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

Accepted Answer

For new users of Immersion Cooling, servicing and maintaining Immersion Cooling is simply different to air-cooled systems. It is not more complicated. Our perspective is that the right approach is to train staff.

Question 22

What’s driving the popularity of Immersion Cooling now?

Accepted Answer

Compute is hot, literally, datacenter densities are going up on all levels: servers, rack and facility. Cooling is becoming a serious issue, combined with the need to integrate sustainability this is a challenge which is complex and expensive with air cooled systems. Immersion Cooling is able to facilitate the next generation hardware and, in an energy, efficient way, while also being climate independent.

Question 23

Is Immersion Cooling not primarily used for cryptocurrency miners?

Accepted Answer

Immersion Cooling is used by all kinds of users, including high performance computing, enterprise, telecom and emerging technologies. Customers of E3 include financial institutions, universities, oil & gas companies, government & defense organizations, cloud providers, telecom providers and more.

E3 NV, LLC

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