Attend any data center conference, and you will find a plethora of new cooling solutions designed to meet the needs of the latest and greatest technologies.

At around 700W and beyond, air cooling for chips becomes increasingly difficult, and liquid-cooling becomes the only realistic option.

Nvidia’s H100 GPUs scale up to a thermal design point (TDP) of 700W, and its Blackwell GPUs can currently operate at up to 1,200W. The company’s recently announced Blackwell Ultra, also known as GB300, is set to operate at a 1,400W TDP, while AMD’s MI355X operates at a TDP of 1,100W.

Recently, liquid cooling firm Accelsius conducted a test to show it could cool chips up to 4,500 watts. Accelsius claims it could have gone even higher but was limited by its test infrastructure, rather than the cooling system itself.

But the reality is that, while much of the excitement and drama in the sector focuses on the needs of AI hardware, the majority of workloads in data centers are not running on these powerful GPUs. The density of these racks is also creeping up, if not to the same level, and many companies are not willing to fully rip and-replace cooling systems in costly and complex programs.

While many companies are looking to reinvent the wheel with flashy new cooling set-ups, a large cohort of data center operators are focused on refining their existing systems, looking to unlock additional efficiencies wherever possible and improve their cooling capabilities at a rate that is appropriate for their needs. One way of doing this is to optimize the fluid used in existing cooling systems.

Nanoscale changes

A large portion of “air cooling” solutions still use liquid at some point in the system – usually water or a glycol-water mix. When it comes to the choice of fluid, water is typically considered more efficient at transferring heat, but water-glycol can be more suitable when freeze protection is needed.

But, regardless of whether it is a water or a glycol-mix base, Irish firm HT Materials Science (HTMS) says that it can make your system more efficient with “nanoparticles.”

HTMS was founded in 2018 by Tom Grizzetti, Arturo de Risi, and Rudy Holesek.

According to Grizetti, the company’s Maxwell solution stems from a research initiative that started more than 15 years ago at the Università del Salento in Lecce, Italy.

The team was exploring how nanotechnology could be used to fundamentally improve heat transfer in fluid systems. Grizetti says of that time: “It’s one of those rare startup scenarios where deep science meets a real-world market need at just the right moment.”

To date, HTMS’s customer base hasn’t primarily been data centers, with its solution currently deployed at industrial sites and Amazon fulfillment centers, but the company is targeting the sector and talking to operators because, it says, it can see a strong use case.

Nanoparticles are ultrafine, tiny particles. In the case of HTMS’s “Maxwell” solution, these particles are over 100 nanometers in size and made of aluminum oxide.

“Our product is a simple fluid additive that goes into any closed-loop hydraulic system, whether that be air-cooled chillers or the vapor side of water-cooling chillers,” Ben Taylor, SVP of sales and business development at HTMS, explains.

Taylor makes the bold claim that Maxwell will improve efficiency at “every heat exchanger in the loop – whether it be the evaporator, barrel, chiller, the coil, or the air handler – they all see better heat transfer capabilities.”

Aluminum is well known for its heat transfer properties. The metal alone has a thermal conductivity of approximately 237 W/mK (Watts per meter per Kelvin), and the aluminum oxide compound (also known as alumina) has a relatively high thermal conductivity for a ceramic material, typically around 30 W/mK.

While having a lower thermal conductivity than pure aluminum, alumina is more suited to cooling systems as it has greater stability and durability, meaning it works well in high-temperature and high-pressure applications, and provides better corrosion resistance. All of which has been backed up by several scientific studies, including the paper ‘Experimental study of cooling characteristics of water-based alumina nanofluid in a minichannel heat sink, published in the Case Studies in Thermal Engineering journal.

The fact is that although alumina is a well-established additive for thermal conductivity solutions, it isn’t widely adopted by the data center industry. While at the Yotta conference in Vegas in 2024, DCD met with HTMS and asked about competition in the industry – only to be told that, currently, they aren’t really facing any.

The nanoparticle solution can be injected into new and old cooling systems, Taylor says, “You get more efficiency in your system, and even if it’s an older system, you can start to do more than you thought you could,” he says.

For many data center operators, this is music to their ears. Ripping out and replacing cooling systems costs time and money, but with the growing cooling needs of hardware and increasing regulatory pressures in many markets, f inding efficiencies is paramount.

There are, of course, upfront costs associated with the installation of the heat-transfer fluids, but HTMS estimates that companies see payback on this within three years, and some in as little as one year.

Efficiency and environmental impact

From the perspective of sustainability, Taylor says that Maxwell’s carbon footprint is low. “A lot of customers will break even on CO2 emissions within the one to three month mark,” he says.

“We are seeing existing systems that need more capacity, and new systems that are trying to be as efficient as possible because a lot of them are going to start taking up a lot of the power grid – and plenty are already using a lot of power.

“They are looking for a more overall energy efficient system, and one option could be a water-cooled chiller set up with open cell cooling towers. But, while they are more energy efficient, they are costly in terms of water consumption,” he explains, adding that Maxwell can only be used in a closed-loop system.

He continues: “The additives are nanoparticles, so if they are open to the environment, especially in an open cell cooling tower, they could just blow away in the wind.

“The other reason is we have a pH requirement. We normally stay around 10 to 10.5, which is pretty standard in a glycol system, but it is a little higher than you would expect in a water system. And if they are open to the atmosphere, the pH will just keep dropping.”

The improvements seen in cooling abilities vary depending on whether the customer uses water or a glycol mix. When Maxwell is injected into the system at a two percent concentration, Taylor says that a water-only system can see around a 15 percent increase in heat transfer abilities, and then with a mix of around 30 to 40 percent glycol, that 2 percent concentration can improve heat transfer capability by as much as 26 percent.

Deploying Maxwell is a simple process, Taylor says. “We have everything pre-blended and then inject it into a system,” he says. “We need the pumps to be running, unless we are filling the system right out of the gate.”

HTMS usually recommends also installing a “make-up and maintenance unit” (MMU) on the site – a device which monitors the system and maintains the appropriate chemistry and mixture of particles.

Jim McEnteggart, HTMS’ senior vice president of applications, explains: “We usually ship at around 15 percent volume. It’s a liquid, and we then pump it through the system through connections typically on the discharge side of their normal pumps.

“The concentrated products mix with their system, and then we train it out on the suction side of the pump. There, the MMU has instrumentation that measures the pH and density. When it reaches its target, we know we have enough nanoparticles in the solution to achieve the desired outcome, and we stop injecting.”

McEnteggart adds that HTMS assumes around a “five percent leaking rate per year” according to ASHRAE standards, but that once Maxwell is in a system, the company says it can last for ten years.

“In reality, everything in the loop won’t degrade the aluminum oxide since it’s chemically inert,” McEnteggart says. “So, unless there’s a leak, the product can stay in there for the life of the system.”

That chemical inertia is also a positive factor in terms of the impact – or lack thereof – that the solution could have on the environment if there were a leak.

“It’s not toxic,” says McEnteggart, though he jokingly adds: “I still wouldn’t recommend drinking it.”

“If it got into the groundwater, aluminum oxide by itself is a stable element that’s not really reactive with many things. But again, the protocol is that we don’t want it discharged into sewer systems or things like that, because at the concentrations we are dealing with, it could overload those systems and cause them not to work as well as they should.”

This is important to note, as additives can sometimes be PFAs – per or polyfluoroalkyl substances, also known as “forever chemicals”. The nanofluids, while considered an additive, do not fall into this category.

Should a customer want to remove Maxwell from its system – which McEnteggart assures DCD none so far have – it’s a combination of mechanical filtration and chemical separation.

“If we lower the pH into the acidic range – so, below seven – the particles drop out of suspension. They settle very quickly, and we can do that on site, just pump the system out into tanks and add an acidic compound to get the particles to collect at the bottom of the tank.

“We extract from there, and then everything else gets caught by a ceramic filter with very fine pores. Then we neutralize the solution, and if it’s water, it can go down the drain, or if it’s glycol, it goes to a treatment facility.”

Alumina, and nanofluids by extension, have not sparked much conversation in the industry thus far.

As a result of this, it occurred to DCD that there may be some issues in providing the solution en masse should the industry show significant interest.

“We would definitely have to scale up very quickly,” concedes Taylor. “But a good thing is that the way the product is made is quite a simple approach. Once we see interest growing, we can forecast that, and all we’d have to do is open up a building and get two or three specific pieces of equipment.

“The only limiting factor would really be the raw material suppliers – for the alumina and, in the future, for the graphene. If we hit snags on that end of things, it would be out of our control.”

HTMS has at least one data center deployment that they have shared in a case study, though the company remains anonymous beyond noting the facility is located in Italy. The likes of Stack, Aruba, TIM, Data4, Equinix, Digital Realty, OVH, and CyrusOne, as well as supercomputing labs and enterprises, operate facilities across Italy.

While unable to share identifying details about the Italian deployment, the total power of the chiller system was 4,143 kW (1.178 RT) and consisted of three chillers and one trigeneration system. According to the case study, the data center saw a system coefficient of performance improvement of 9.76 percent.

But a big part of the challenge when entering a long-secretive industry is getting your name out there if clients won’t let you share their story.

“A lot of them [data center operators] are pretty sensitive about having their names out there,” admits Taylor, though the company remains hopeful that it will fully conquer the data center frontier.