Continuing our exploration into cutting-edge data center cooling solutions, this installment delves into the evolving role of cold plate technology, a powerful thermal management technique that is rapidly gaining traction as data centers grapple with soaring heat densities. Traditional cold plates use a single-phase heat transfer process, where the fluid remains in liquid form throughout the process. However, as computing processes become more intense, the industry has been exploring two-phase cold plate liquid/gas cooling as well. In our previous article, we explored the Belimo EPIV and its innovative role in fluid management for data centers. In this entry, we will discuss single and two-phase cold plate systems and the role Belimo products play in this emerging technology. As computing demands increase, understanding these advanced cooling strategies becomes crucial for data center operators, who are responsible for maintaining efficiency and reliability at their facilities.
We invite you to join us for an upcoming 20-minute webinar on Wednesday, November 13, 2024, at 1:00 pm EST, where we will explore the intricacies of cold plate systems and how they can optimize your data center's cooling and efficiency. Click here to sign up for insights that will help future-proof your data center cooling strategies.
Single-Phase Liquid Cold Plate Solutions
Single-phase cold plates are increasingly being deployed to manage the extreme heat generated by today’s servers, far surpassing the capacity of traditional air-cooled systems. Traditional air cooling typically handles 8 kW to 12 kW per rack, with a maximum of about 20 kW per rack. In contrast, liquid cold plates can manage heat loads of up to 100 kW per rack or more, thanks to the much higher thermal conductivity of liquids compared to air. This substantial difference allows data centers to support the next generation of high-performance computing systems, including AI servers, machine learning applications, and crypto mining rigs.
The mechanics of single-phase cooling involve a metal plate, often copper or aluminum, that makes direct contact with the heat-generating components such as CPUs and GPUs. Fluid is circulated through channels inside the cold plate, absorbing heat as it passes through and transferring it away from the server.
Controlling flow through cold plates is vital because too little flow can lead to poor heat transfer and potential damage to the electronics, while too much flow can cause erosion within the cold plate channels. Belimo’s advanced control valve solutions for cold plate applications, such as the EPIV and Energy Valve, deliver predictable, stable flow rates while providing unrivaled transparency via real-time flow measurement data reporting. The Energy Valve is also capable of differential pressure control, ensuring proper flow even when servers are removed from the rack. We’ll cover this innovative functionality in greater detail in our next blog post.
While cold plates offer impressive heat removal, they typically do not eliminate all heat from the system. For this reason, many data centers using liquid cold plates still incorporate a hot aisle/cold aisle-type air cooling system (or another form of air cooling) to handle residual heat loads.
Two-Phase Cold Plate Solutions
Two-phase cold plates take thermal management a step further by employing a phase change from liquid to vapor to significantly boost cooling efficiency. This method of cooling is often used in demanding, high-power-density applications where single-phase cooling systems fall short of providing the required cooling performance. The two-phase cold plate capitalizes on the latent heat of vaporization, absorbing large amounts of heat during the liquid-to-gas transition without a significant temperature increase, making it highly efficient. While two-phase cold plate systems are still new and their install base still relatively small, the efficiency gains from leveraging the phase change make them well worth the added complexity in many cases.
Two-phase cold plate systems are pumped refrigerant systems, as opposed to the compressor-based systems typically seen in the DX (direct expansion) units used in traditional air cooling. The diagram below shows the typical equipment used in a two-phase cold plate refrigeration cycle.
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In two-phase systems, the coolant enters the cold plate and is exposed to the heat source, such as a CPU or GPU. As the liquid heats up and boils, it transitions into vapor, carrying heat away from the component. The vapor is then directed to a condenser or heat exchanger, where it is cooled using air or liquid, reverting back to its liquid state before being cycled back into the cold plate. This continuous process of vaporization and condensation allows for a more efficient removal of high-density heat loads than single-phase systems.
Conclusion
As server density and computing power continue to rise, traditional air-cooling solutions struggle to keep up, driving the need to explore new, more efficient cooling methods. Liquid cold plate solutions—whether single-phase or two-phase—offer a way forward, providing greater thermal management capabilities by leveraging the superior heat transfer properties of liquids. While single-phase solutions are quite effective, the potential of two-phase cold plates promises even greater efficiency for the most demanding data centers. These solutions allow facilities to maintain the familiar layout of server racks while drastically enhancing cooling efficiency, all without needing to resort to more drastic measures such as immersion cooling (a topic we will explore in-depth in a future blog post). Belimo products can support these systems by providing efficient and reliable fluid management, along with transparent real-time reporting, ensuring optimal performance and greater operational control.
We encourage you to join our upcoming webinar on Wednesday, November 13, 2024, at 1:00 pm EST for a deeper dive into these liquid cooling technologies. Learn how to future-proof your data center with advanced thermal management strategies that can handle the heat loads of tomorrow. Click here to reserve your spot.