Is liquid spray cooling the future for data centres?

Maintaining the temperature of critical infrastructure within Data Centres through the use of air-cooling technology has dominated the industry for many years, whilst the demand in data consumption has increased year-on-year and in turn has increased the amount of electricity consumed. Electricity consumption for IT and Cooling systems accounts for approximately 86 percent of the total energy consumption within a Data Centre, while cooling alone can account for up to 40 percent.

Furthermore, in recent years we have seen server technology evolving at a fast pace, resulting in an increase in heat density. Typically, heat density increases by an average of 1kW per rack every 2 years and we are now starting to reach the point where the effectiveness of air-cooling technology, in some cases, is restricted due to the air’s heat transfer coefficient, which limits its ability to remove heat from today’s modern chips. Dealing with this issue has been at the forefront of industry debate. The solution in overcoming these limitations is Liquid Cooling.

Some Data Centres are already adopting Liquid Cooling, but the specific technology that has so far been predominately implemented is immersion cooling. Although it is an efficient method in removing heat from CPUs, the technology still has some reliance on mechanical cooling, which makes it less sustainable, and limits the ability of the Data Centre in moving closer to net zero. Combined with the growing pressures of the global energy crisis and repurposing waste heat from the Data Centre, what could be the solution? 

Established in 1995, Airsys is a market-leading cooling solutions provider, who think globally, but act locally. We deliver innovative, high-efficiency, precision control thermal solutions for the built environment. With over 25 years’ experience, combined with multiple manufacturing facilities and offices globally, Airsys are able to deliver sustainable solutions for critical environments such as Data Centres and Telecoms environments. A focus on understanding the customers’ needs, combined with our technological expertise, has allowed Airsys to develop a liquid spray cooling solution, called the LiquidRackTM which addresses the current limitations of existing technology and moves Data Centres closer to achieving their sustainability goals. 

LiquidRack ™is a liquid spray cooling solution designed for multiple types of digital data infrastructures, such as cloud service, telecommunication facilities and more. Differing from immersion cooling, our pioneering approach keeps the dielectric fluid moving, spraying directly onto the CPU. Adopting a liquid spray cooling approach significantly increases the heat transfer coefficient, in comparison to immersion cooling.

Increasing the heat transfer coefficient, allows the dielectric fluid being sprayed on the CPU to be elevated up to a temperature of 65oC, without comprising performance of the CPU. This provides two major benefits. Firstly, the elevated fluid temperatures eliminate the need for chillers, and they can be replaced by dry coolers in environments with ambient temperatures up to 50oC. This means that there are potential free-cooling applications in geographic locations such as the Middle East, for which free-cooling has been traditionally hard to achieve. Secondly, the elevated water temperatures allow for heat recovery. 

Heat recovery means that the recovered energy from the Data Centre can be recycled for multiple applications, such as district heating and industrial scale greenhouses to name but a couple. The Data Centre now becomes an energy producer, helping to achieve Net Zero emission goals. LiquidRack™ can offer a seamless connection for heat recovery to district heating systems, due to the high running temperatures, which is another advantage to the solution.

The largest obstacle for the adoption of liquid cooling technology has always been the significant expense involved in transitioning away from air-cooled solutions in existing Data Centre environments. The project complexities and capital expenditure were previously considered to be high-risk. LiquidRack™ changes this, now the transition is seamless. LiquidRack’sTM vertical design, size, and lower operational weight, when compared to immersion technology, allow for easier integration into existing Data Centres. Each LiquidRackTM consists of two drawers, with each drawer, for our standard design, able to accommodate up to 6 x 2U servers, therefore each system can hold up to 12 x 2U servers. LiquidRack™ has been designed to provide a cooling capacity of up to 80kW. Each server can be slid out and locked into position for hassle-free inspection and maintenance. The system is fully adaptable to different server brands, different server layouts and even a mixture of CPUs and GPUs within the same drawer. Designed as a decoupled system, each drawer contains two low powered pumps (N+1) and a highly efficient heat exchanger. The LiquidRackTM design offers an unbeatable fantastic cooling capacity when compared to its modest footprint. As the LiquidRackTM directly cools the CPU via spray technology, not relying on immersing the server, the dielectric fluid needed is typically reduced by 80% when compared to immersion technology. This provides CAPEX advantages in terms of dielectric fluid procurement and reduces structural issues in relation to weight. 

By spraying directly onto the CPU, the LiquidRackTM provides a constant flow and eliminates uneven fluid flow that can occur using other methods of liquid cooling technology, which can result in server reliability issues. Uneven flow can occur when there is a mixture of different servers immersed or if one or more servers are removed for maintenance, resulting in the dielectric fluid following through the path of least resistance, thus starving the CPU of the flow needed to remove heat. Therefore, LiquidRack™ offers a more reliable solution to preserve servers and maintain Data Centre uptime.

As data consumption becomes ever more important in our day-to-day lives both personally and professionally, global Data Centre electrical consumption is predicted to reach 4% of the total global electrical consumption by 2030. A combination of the world’s reliance on gas and oil, and the surging costs associated with them, turbulent energy prices affecting operating costs and budgetary planning, and the need to move towards a more sustainable future, are driving change in the industry. The Data Centre community needs to quickly adapt and Airsys passionately believe they have a game changing technology that provides a low CAPEX and low OPEX solution that can turn a Data Centre into an energy producer, whilst achieving free cooling anywhere in the world. Liquid Cooling is the next step for the Data Centre industry to achieve their aims of sustainability and Net Zero, and liquid spray cooling is the pioneering next step in the liquid cooling journey.