The latest trends and developments in cooling solutions

Author: Beatrice

This article was contributed to DCNN by nVent, on the latest trends and developments in cooling.

For facility planners, thermal engineers, architects and managers responsible for implementing powerful IT Equipment (ITE), the goal is to maintain high availability at minimal operational costs, while minimising energy consumption. To do so, all equipment must be kept below a specified temperature range. However, legacy cooling in data centres, server rooms and other IT environments use technology based on traditional air conditioning systems that alone struggle to keep up with the rising heat load demands of today’s high-density, high-performance connected technologies. Consequently, sustainability gets sacrificed, and facilities can experience equipment failures, unplanned downtime and soaring energy costs.

To run the latest and greatest IT equipment, liquid cooling has become the standard, and high-performance servers are designed with liquid cooling installed. In the right applications, these will offer a strong return on investment and total cost of ownership when compared to non-liquid approaches. In recent years, the range of liquid cooling solutions has advanced to help meet the unique protection needs of applications in virtually any environment.

Whether for smaller decentralised edge computing, harsh environments, or large data centre installations, no one size fits all approach exists for thermal management. This article shares key considerations for choosing among the comprehensive range of standard and customised air, indirect and direct water-cooling solutions. It also provides guidance on identifying which solution will best protect your ITE assets and your bottom line.

Understanding the range of cooling solutions

The advanced thermal management solutions that exist today offer the breadth, flexibility and modularity needed to meet unique application needs and address a range of ITE heat-load challenges. For reference, the primary cooling approaches include:

• Air cooled – Heat is transferred directly to the room air and cooled via traditional data centre cooling
• Indirect water-cooled – Heat is transferred indirectly to water through an air-to-water heat exchanger located within the row or single cabinet
• Direct water-cooled – Heat is transferred directly to an attached heat transfer component, such as a cold plate.
• Hybrid direct and indirect water-cooled – Selective cooling of highest energy-consuming components with direct contact liquid cooling and the balance of the cabinet is cooled via secondary air-to-water cooling device, such as a Rear Door Cooler (RDC). 

Air cooling is becoming less feasible in high density data centres, as heat loads increase and server racks become so densely configured that air circulation is impeded. Today’s air cooling solutions generally can manage 10 kilowatts or less cost effectively. Data centres that try to cope by increasing air velocity can quickly become a wind-tunnel-like environment that is difficult to work in. With this in mind, as energy needs increase, so does the likelihood of needing a liquid cooling component to your thermal management strategy.

Liquid cooling systems offer effective solutions for achieving required temperature parameters and lowering energy consumption of the cooling system, thus lowering operating costs. Liquid provides a much greater heat transfer capacity – 3,500 times higher than that of air – because it is denser than air. Subsequently, direct-contact liquid cooling (direct-to-chip) in which a coldplate is placed directly on processors inside the server presents the highest efficiencies. The coldplate has internal micro channels and an inlet and outlet through which liquid is circulated to carry away heat. Low-profile coldplates used in direct-contact liquid cooling also have the advantage of taking up much less rack space than traditional heat sinks.

However, while liquid cooling offers huge advantages in moving heat, managing the entire heat load of the rack with liquid cooling methods can be unnecessary and cost prohibitive for some applications. In many cases, a hybrid solution – combining both liquid and air cooling – often is a more accessible and scalable deployment option, that effectively leverages the highly efficient heat transfer of liquids. For example, more current cooling designs include aisle containment and rack-based cooling. These models increase efficiency and often incorporate an air-to-liquid heat transfer to leverage the higher heat transfer qualities of liquids.

Choosing the right solution for your application

To determine the most efficient and effective cooling technologies and layouts for your specific IT hardware, it is important to evaluate the current and future thermal profile of the environment, and model the necessary infrastructure modifications or layout changes. As you do, also consider these important factors:

• Existing equipment capabilities. The placement of IT equipment, air handlers, close-coupled cooling, and direct liquid cooling technologies within the data centre, server room, or other ITE environment is critical to the efficient use of available space and cooling capacity.
• Current cooling needs and anticipated future ones, taking into account potential technological advances, business growth and other objectives.
• Current, pending and trending global standards as well as relevant regulations.
• Resources vs. return on investment and total cost of ownership.

The placement of IT equipment, air handlers, close-coupled cooling, and direct liquid cooling technologies within the data centre, server room or other ITE environment is critical to the efficient use of available space and cooling capacity. Lead time for facility upgrades and capital planning requirements mandate comprehensive planning.

For example, a university or research facility may only have 6-10 racks, but require liquid cooling because of the high-performance computing power In one recent case, a global IT original equipment manufacturer needed robust cooling for its data centre. In comparing an air cooling solution and a liquid one, they found some critical differences. Both solutions work, but the liquid cooling solution offered significant footprint and energy efficiency advantages. It also set the OEM up for future upgrades as advances in technology increase the performance power and density needs.

Depending on your specific application and environmental needs, myriad solutions exist. So, you need to weigh the options to determine the most appropriate cooling solution.

Once you have determined the right cooling solution for your application, you will need to gather relevant data on your facility requirements to help ensure a smooth, streamlined installation. This will entail providing detailed information on the equipment, configuration, thermal attributes and design needs of your primary loop, secondary loop, and architecture, as well as any unique requirements. You also will want to create a routine maintenance plan. For liquid cooling solutions, this will include scheduling required inspections and ordering replacement parts in advance to make sure the fluid in the system is within safe operating range.