Coolant distribution units

New, higher power applications require more efficient cooling for high heat loads in compact volumes; this typically leads engineers to turn to liquid cooling solutions. Design engineers have creatively driven air-cooling innovation to impressive performance levels for product design teams reticent about introducing liquid cooling into high reliability data center systems. However, new requirements are making it increasingly difficult to avoid liquid entirely. Overlapping technology portfolios enable liquid, immersion, two phase and air cooling innovation to coexist, allowing engineers to blend the right solutions for each custom application to extend the performance boundaries of traditional air cooling systems and assure a safe migration to liquid cooling systems when appropriate. Thermal and power density demands of next generation designs have now reached air cooling limitations, requiring the transition to liquid. Liquid is much more efficient and has the capacity to transfer heat up to 4X higher than the capacity of forced air of the same mass. This enables faster, more cost-efficient, quieter, better performing applications through efficient, improved heat transfer and higher thermal performance with increased design flexibility and scalability. Increased efficiency and smaller systems also save space, allowing for more racks and servers operating at higher performances.

A liquid cooled system is a hydraulic circuit that typically consists of a cold plate that interfaces with a heat source in a device, hoses and pumps that circulate fluid through the system and a heat exchanger that rejects heat into the ambient environment. Liquid cooled systems are becoming much more common as air cooling is unable to handle new, higher heat loads and liquid cooling reliability is proven through many hours of in-field installations with leak-free performance. CDUs are the core of the liquid systems and are designed to increase overall system efficiency and reduce total cost of ownership for the data center.

In-rack CDUs are designed to integrate into a server chassis and distribute coolant to a series of servers or heat sources. In-rack CDU configurations are available for 4U to 10U sizes, installed within server chassis and offer 60 – 80kW of cooling capacity. These feature redundant pump design, dynamic condensation-free control, automatic coolant replenishing, a bypass loop for stand-by operation and automatic leak detection.

Freestanding In-row CDUs are larger and designed to manage high heat loads across a series of server chassis in data center environments. These full liquid cooling systems distribute coolant in and out of server chassis and can integrate into existing facility cooling systems or be designed to be fully self-contained. In-row CDU capacity ranges start at 300 kW with models in development that cool up to 700kW.

Eaton CDU key features and benefits

• Redundancy – Increase reliability and enable continuous operation for less downtime and lower maintenance requirements through design redundancies such as multiple pumps utilizing N+1 configurations.
• Hot swap – Further decrease downtime and enable continuous operation for a more efficient, higher producing facility by ensuring components such as pumps and cold plates can be swapped out or replaced while still hot, negating the need for cool down time.
• Communication portal – Increase precision, monitoring and control for greater efficiency with improved connectivity and control of the system through an advanced communication portal. Better data and monitoring to proactively scale or alter thermal systems for optimized application performance.
• Wetting chemistry – Leverage Eaton’s decades of experience in liquid cooled systems that has resulted in a wealth of knowledge and innovation, including a deep understanding of wetting materials for the components in a liquid loop and how to best integrate technologies for fully optimized, highly reliable systems.

CDU design considerations

• Mechanical design – Each component must be carefully selected for high reliability and long life independently and as a system. This includes all pumps, power supply and the heat exchanger. One flaw could cause the entire system to fail, causing downtime and device failure. It is vital that suppliers are streamlined and well-vetted to ensure high quality components. Eaton engineers ensure that all components within the system are tested to ensure they will work reliably and to customer specifications.
• Communication / controller and monitor – Save on maintenance costs and potential downtime by ensuring that the system can easily communicate with the resident network to control the system remotely and monitor alarms. The quicker that issues can be identified and handled, the less potential for device failure, emergent maintenance needs, inefficient energy usage and other risks.
• Leak detection / condensation risk – Many facility managers hesitate to utilize liquid cooling because it could cause major application failure if any amount of liquid gets into the compute devices. It is essential that liquid cooled systems and CDUs are completely leak-free with no condensation. Eaton has decades of expertise in leak-free development and testing as well as liquid cooling systems installed in market applications since 2007 with over 30.6 billion field hours with zero leaks. As an additional measure of protection, Eaton installs leak detection systems to monitor potential leaks, provide alarms and drive preventive maintenance. The system can also be used in data centers operating below dew point to monitor condensation risk on pipes within the system.
• Maintenance – In addition to monitoring with controls and communication portals, liquid cooled systems for data centers require regular preventative maintenance to ensure higher reliability and optimum performance. Be sure that your organization understands the maintenance costs required when considering liquid cooling and how these are offset by improved efficiency, more available space and better application performance.
• Heat exchanger – Your choice in heat exchanger has a significant effect on the overall efficiency, size and performance of the liquid system. To augment the reliability and performance benefits of utilizing a CDU, a high efficiency, brazed, heat exchanger is recommended. Depending on liquid cooling system design, compact heat exchangers in fully self-contained CDUs or rear door heat exchangers integrated into a server chassis may be most appropriate to optimize full liquid system efficiency and performance.

Processing and data storage needs will continue to increase exponentially as organizations and individuals further demand digitalization, greater functionality, increased speed and service, better connectivity and more electronification globally. To support this global trend, data centers and enterprise applications need to be larger, more efficient and operating 24/7 with improved processing and storage efficiency. This will, generate greater thermal density and higher heat loads as never seen before in enterprise technologies. Data centers will need to adapt their thermal management strategy quickly to accommodate the fast changing landscape and increased heat. Liquid cooling systems and CDUs will play a big part in these new strategies.

With decades of innovation expertise, experience and supplier partnerships, coupled with the unique approach of integrating multiple technologies into a streamlined product, Eaton will continue to stay at the forefront of innovation and improved manufacturing that offers unsurpassed reliability and performance while lowering overall costs to the data center operator. If you are looking to solve current issues or tackle new challenges for the next generation, start by contacting Eaton to learn more about thermal solutions, customizations and improved processes for cloud, enterprise and 5G applications.