Exploring the Rise of Hybrid Cooling Systems for Data Centers

KUUL DATA CENTER TEAM | FEBRUARY 2024

Data centers have become the backbone of our digital age. They power everything from cloud computing to our daily communication interactions. As data centers continue to evolve and expand to meet the ever-growing demands of our technological infrastructure, they are becoming more dense and emitting more heat than ever before.

Given the increased reliance on data centers, the cooling systems that keep these data centers running efficiently are constantly being evaluated for improvements, or to determine if new system types can increase efficiency and sustainability.

Hybrid cooling systems have grown in prominence recently both in the industry discussions and in adoption within data centers. However their recent rise in popularity have left many searching for answers as to their function, efficiency and how to optimize them.

This article will explore hybrid cooling, what it is, and why it has become such a large topic of exploration within the industry today.

Which Type of Hybrid Cooling?

First we must define what type of hybrid cooling we are referring to. Hybrid cooling is a versatile approach that finds application in two primary facets of data center cooling: within the data hall itself and with external condensers. 

The term “hybrid cooling” is often used by different groups to mean either approach so it’s important to clarify what type of hybrid cooling is meant to avoid confusion. Our focus in this article will revolve around its implementation within the data hall, specifically directed toward the cooling of IT equipment.

1. Air Cooling Systems

While air cooling systems can take many different forms, two of the most common ones are direct evaporative cooling or a coil based cooling system. Air cooling systems are how data centers have been cooled for the past thirty years and have been a foundational pillar in data center cooling over their comparatively short history. 

How They Work in Data Centers

• Air circulation: Cooling systems circulate air throughout the data hall. Hot air generated by IT equipment is either exhausted out of the data hall and replaced with fresh, cold air, or the air is sent to a cooling system in the data hall.
• Air cooling: For systems which use outside air, the air is conditioned to an optimal temperature and humidity before being sent to the data hall. For systems that recirculate air within the data hall air is passed over cooling coils to remove heat.
• Raised floor or overhead ducts: Some data centers employ raised floors or overhead ducts to distribute cool air effectively. Cold air is supplied through floor grates or overhead vents to reach the IT equipment, while warm air is removed through the ceiling or a raised floor return system.
• Air filtration: Air is filtered to remove dust, contaminants, and other particles that could potentially damage the IT equipment.

EXPLORE EVAPORATIVE COOLING FOR DATA CENTERS

2. Liquid Cooling Systems

Liquid cooling involves the use of liquids, most commonly water or dielectric fluids, to absorb and transfer heat. This method is becoming increasingly popular, particularly in advanced data center configurations. It can take two primary forms: direct-to-chip, which involves placing cooling elements directly on CPUs or GPUs, or immersion cooling, where entire server systems are submerged in a cooling liquid.

How They Work in Data Centers

• Direct Heat Transfer: In this method, a liquid coolant, often water or a dielectric fluid, is brought into direct contact with the hot components, such as CPUs or GPUs.
• Heat Absorption: The liquid coolant absorbs the heat generated by these components and then carries it away from the source.
• Heat Exchangers: To reject the absorbed heat, liquid cooling systems typically use heat exchangers to cool the liquid coolant.
• Efficient Cooling: This method is highly efficient at removing heat from high-power components and is often used for demanding workloads such as artificial intelligence and machine learning.

3. Hybrid Cooling Systems

Hybrid cooling systems combine facets of both air and liquid cooling. In this approach, air cooling and liquid cooling technologies work together, to create a third type of cooling option within a data center. 

How They Work in Data Centers

• Seamless Transition: Hybrid systems are designed to seamlessly switch between air cooling and liquid cooling based on the specific cooling demands.
• Air Cooling Utilization: Generally an air cooling component is responsible for cooling the IT equipment components with a lower heat density and the overall temperature maintenance within the data hall. 
• Liquid Cooling Utilization: Liquid cooling technology is then typically leveraged for targeting specific areas or equipment that needs more intensive cooling due to high heat output. 

Want to learn more about the intricacies of these cooling solutions and how to gain optimal efficiency? Explore our webinar in partnership with the ASHRAE Journal featuring experts from our team, Sean Barlett and Cody Weeks.

Why Hybrid Cooling Systems Have Grown in Usage

The benefits of hybrid cooling systems have propelled their growth in adoption and have increased discussion about broader usage industry wide. The reason consideration of hybrid cooling has grown within the industry typically revolves around one or more of the following benefits. 

1. Customizable Cooling: The synergy between air and liquid cooling allows for a tailor-made approach, offering a spectrum of configurations that can be fine-tuned to optimize energy consumption and operational efficiency based on the specific requirements of the data center.
2. Cold Plates Targeted at Specific Components: Liquid cooling technology using cold plates is directed specifically at critical components that produce higher heat levels. By concentrating cooling efforts on these hotspots, it ensures efficient and precise temperature control for these areas, preventing potential overheating issues.
3. Reduced Tubing Requirements: The hybrid cooling approach significantly reduces the need for extensive tubing throughout the data hall. With a blend of air and liquid cooling strategies, the overall requirement for complex networks of tubing is notably minimized, streamlining the system and reducing complexity.
4. Less Pressure Balancing: Compared to systems entirely reliant on liquid cooling, the hybrid approach reduces the necessity for complex pressure balancing systems. The integration of air cooling alleviates the burden on pressure balancing requirements associated with exclusive liquid cooling solutions, resulting in a more simplified and manageable cooling infrastructure.

Given the trend around hybrid cooling systems, it’s clear that they aren’t going away anytime soon. 

EXPLORE DATA CENTER COOLING SOLUTIONS

Benefits of Using Direct Evaporative Cooling in Hybrid Systems

Even with full adoption of a hybrid cooling system within a data center, the cooling system still needs some type of air cooling to function correctly. Using direct evaporative cooling as the air cooling component of the cooling system instead of a coil based system proves to provide greater efficiency in many cases. 

When hybrid systems incorporate direct evaporative cooling for the air cooling component they leverage the advantages of traditional cooling methods including:

1. Energy Efficiency: Evaporative cooling systems generally consume less energy compared to coil-based systems. They work by utilizing the natural process of water evaporation to cool the air, reducing the energy required for cooling. This results in lower operational costs.
2. Environmental Impact: Evaporative cooling systems have a reduced environmental impact. Unlike coil-based systems that often rely on refrigerants or other chemicals, direct evaporative cooling primarily uses water as its cooling medium, making it a more environmentally friendly option.
3. Efficiency in Dry Climates: Evaporative cooling is particularly effective in dry or arid climates where traditional coil-based systems might struggle due to the lack of humidity. Direct evaporative cooling adds moisture to the air, making it a suitable solution for regions with low humidity.

Kuul: Pushing the Boundaries of Evaporative Cooling

While hybrid cooling systems are at the forefront of many industry discussions today, Kuul’s dedication to the advancement of evaporative cooling serves as a reminder that traditional methods can still be innovative. 

Part of that innovation involves working to optimize evaporative cooling technology for hybrid cooling systems. It also looks like developing new and revolutionary products using evaporative cooling technology. That’s why we continue to push the boundaries as to what’s possible with evaporative cooling. 

With Kuul’s recent merger with Condair we now offer an even broader range of solutions and capabilities for data centers to ensure that your data center is optimized for efficiency.  

Whether you’re pursuing adopting a hybrid cooling system, looking for ways to optimize your existing air cooling system, or are unsure of what cooling option is best for your environment, we are here to help. 

EXPLORE DATA CENTER COOLING SOLUTIONS