Making Liquid Cooling Work from Design to Operations
Liquid cooling systems are helping data centres address the plethora of issues associated with the heat generated from IT equipment, by complementing or replacing traditional air cooling systems with liquid solutions that will drive energy efficiency and improve thermal stability.
By harnessing the inherent heat transfer properties of liquids – specifically their ability to absorb and transfer heat faster than air – dielectric coolant fluids or water can be used to directly extract heat from hard-working kit within data centres, preventing overheating and optimising performance.
Installation is such that the heat-generating components are placed in direct contact with the infrastructure of the liquid cooling system. Firstly, the coolant in question travels via pipes and heat exchangers – within a closed system – to directly cool the adjacent components.
The cool liquid absorbs heat, and heat transfer takes place. As the temperature of the coolant rises during heat transfer, the warm liquid is then pumped to a heat-exchanger to be returned to a cool temperature, enabling it to do its job once more. The cooled liquid is then recirculated within the closed system and the cycle continues.
What is driving the switch to liquid cooling?
The global data centre landscape is undergoing a profound transformation: the rapid expansion of artificial intelligence, machine learning and high-performance computing is reshaping not only our IT systems, but also the way that we manage energy, heat and cooling.
Within this shifting landscape – and factoring in the heat created by the rising demand for data – liquid cooling delivers clear advantages over air systems, particularly in terms of energy savings and reduced footprint, as well as providing robust foundations for sustainability improvements.
For example, thanks to the technology’s heat transfer properties, Power Usage Effectiveness (PUE) can be improved by up to 45%, with values below 1.2. With higher outlet temperatures of up to 60°C, it is possible to recover and reuse that heat for other applications.
Water conservation is also possible in part – depending on the heat rejection design – due to the elimination of evaporation losses but largely thanks to reduced consumption as a result of the closed-loop system design.
Liquid cooling can be introduced within new and existing data centre infrastructure
The latest hybrid systems make it possible for every facility to benefit from the advantages that liquid cooling delivers, with the opportunity to more effectively regulate temperatures even in high density infrastructure.
What’s more, these hybrids help ease the transition over time – combining the best of both worlds over a number of years, supporting the need to scale in the face of AI demands, for example, without disruptive redesign or the displacement of existing IT loads.
What should be considered when designing-in liquid cooling systems
Liquid cooling solutions will certainly evolve the design of a data centre, reducing its overall environmental footprint by supporting greater power density and reduced energy consumption – but it will also change the engineering and operation of a building.
Future scalability and density needs should be considered early in the design phase - specifically, piping routes and hydraulic capacity. Operators must also consider the practical impact of working with fluids – from potential leaks to the process and quality control of specific coolants – as training will be critical when it comes to easing the operational transition.
The key principles of heat transfer and water reuse will inevitably guide system design, but industry standards such as EN 50600 have been developed to help support operators and developers, particularly when it comes to understanding metrics pertaining to energy efficiency and lifecycle. For guidance around temperature and humidity ranges, operators should consult ASHRAE TC 9.9.
