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Data Center Cooling Systems: Coolant Distribution Unit Liquid Cooling


Last updated Jun 26, 2024 | Published on Jun 25, 2024

Mastering IT Cooling: The Power of Liquid Cooling Solutions

The ever-increasing demands of data center infrastructure management (DCIM) create a scorching challenge: heat. Traditional air-cooling struggles to keep pace, threatening data center performance and equipment lifespan. Liquid cooling is the most effective solution for modern data centers with enhanced efficiency and higher cooling capacity. To keep high-powered CPUs, GPUs, and network switches within thermal specification, coolant distribution units (CDUs) deliver broader cooling capacity to liquid cooling loops and cold plates that thermally interface directly with heat sources for increased efficiency and greater flexibility than traditional air-cooling.
Data Center Cooling Market Size And Forecast 1
1714650409612 data center liquid cooling market Market Summary

The Future of the Data Center Cooling System Market

The Data Center Cooling Market is projected to reach USD 30,2 Billion by 2030, growing at a CAGR of 13,8 % during the 2024-2030 forecast period, and the industry is witnessing a significant shift towards liquid cooling solutions to meet the escalating cooling demands of modern data centers. The global data center liquid cooling market is expected to grow at a 23,31 % CAGR from 2024 to 2029. Boyd designs CDUs to optimize these liquid cooling systems, ensuring precise temperature control and efficient heat removal in data centers.

What Are CDUs?

Coolant distribution units (CDUs) or cooling distribution units orchestrate precise thermal management within high-performance environments. Coolant distribution units actively distribute coolant water or other fluids to various components of a machine or process that need liquid cooling. This process begins with the liquid coolant absorbing heat from high power equipment through a liquid cold plate or a series of cold plates called a liquid cooling loop. The heated coolant then flows through heat exchanging technology within or outside the CDU, dependent on the configuration, dissipating the heat. Typically integrated into large-scale data center infrastructure, data center racks, laboratories, and semiconductor fabrication factories, CDUs are essential to maintain optimal operating conditions in data centers, industrial settings, and other environments where precise temperature control is critical. CDUs ensure that next-level performance cooling is efficiently and safely delivered to system components and heat sources, safeguarding against overheating and optimizing performance and longevity.

How do CDUs Work?

Coolant distribution units (CDUs) operate through a sophisticated pump system that circulates coolant, typically water or specialized fluids, through an intricate network of pipes or channels. This circulating coolant, essential for thermal dissipation, targets critical components like processors and switches in large-scale, high-power data center systems. CDUs integrate additional components such as valves, filters, and monitoring mechanisms to optimize cooling efficiency and system reliability. Precisely calibrated valves allow for dynamic coolant distribution adjustments tailored to individual component needs, while filters ensure purity by sieving out impurities and contaminants. Equipped with sensors, CDUs continuously monitor coolant parameters like temperature, flow rate, and pressure levels, enabling real-time interventions to maintain peak thermal performance and reliability in complex environments.

What Parts Are In a CDU?

Most Coolant Distribution Units (CDUs) share common components, such as pumps, heat exchangers, microprocessor controls, water quality control systems, and coolant handling manifolds to ensure consistent functionality across various models. These components form the backbone of CDU systems, facilitating sustainable cooling within data centers and other industrial applications. They orchestrate the intricate process of high performance cooling, crucial to seamlessly operate sensitive high power equipment and machinery, embodying cutting-edge engineering and technological innovation.


The pump circulates coolant through the system, ensuring a steady flow of liquid to absorb heat from equipment.

Heat Exchangers

Liquid to air heat exchangers transfer heat from the coolant to the surrounding environment, facilitating efficient heat dissipation for facilities that are not plumbed for liquid. Liquid to liquid heat exchangers transfer heat from the primary liquid loop to the secondary facility water system.

Microprocessor Controls

Microprocessor controls manage and regulate CDU operations, adjusting coolant flow rates and other parameters to maintain optimal temperature and performance, adjusting automatically to compute demand.

Water Quality Control Systems

Water quality control systems monitor and maintain the purity and chemical balance of the coolant, preventing corrosion and sustaining long term reliability.

Coolant Handling Manifolds

Coolant handling manifolds distribute coolant to different components within the CDU system, ensuring uniform cooling across all parts. Certain CDU models integrate specialized components designed to address specific cooling demands or environmental challenges. These components not only augment functionality but also offer unique features catering to a wide spectrum of user requirements. Engineered with precision, these specialized elements optimize cooling performance and ensure seamless operation in varied operating conditions. Their seamless integration and interoperability underscore the adaptability of CDU systems, capable of meeting the diverse cooling needs and demands of modern data centers and industrial facilities.

What Types of CDUs Are There?

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Coolant Distribution Units (CDUs) maintain optimal temperatures within data centers, ensuring servers and other IT equipment operate efficiently. Different types of CDUs meet various cooling needs and configurations. The main types include In-Row, In-Rack, Liquid to Air (L2A), Sidecar, and Liquid to Liquid (L2L) CDUs. Each type offers unique features and applications, tailored to specific cooling requirements.

In-Row CDUs or Sidecars

In-Row CDUs sit between server racks or at the end of a row of server racks and cool a series of server racks. They absorb heat directly from servers using chilled water or refrigerant. Cooled liquid circulates in a closed-loop system on the secondary cooling side, while facility water is used on the primary heat rejection side. In Row CDUs can cool up to 2300KW and are able to an array of 10 high-power server racks.
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A freestanding in-row Coolant Distribution Unit

In-Rack CDUs

In-Rack CDUs provide highly localized cooling to equipment since they are installed within the server rack. These units feature liquid to liquid or liquid to air cooling. Liquid cooled CDUs circulate coolant through a liquid to liquid heat exchanger within the rack unit, cooling the secondary loop with the primary facility water system. For air cooled facilities, liquid to air coolant distribution units draw from the cool air in the facility, cool the liquid loop through a liquid to air heat exchanger, and discharge the heated air into the facility. In-Rack CDUs seamlessly integrate into high-power devices like cloud data center servers or medical and industrial models. They simplify server rack cooling with easy installation and maintenance. These systems offer a cost-effective and reliable cooling upgrade by fitting standard server configurations and offering flexibility for self-contained or integrated setups.
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Liquid to Air (L2A) CDUs

Liquid to Air (L2A) CDUs efficiently transfer heat from a liquid coolant, typically water or a water-glycol mixture, to the surrounding air. This process begins with the liquid coolant absorbing heat from data center equipment through a liquid cold plate or a series of cold plates called a liquid cooling loop. The heated coolant then flows through a heat exchanger within the CDU, where fans blow air over the exchanger, dissipating the heat. L2A CDUs leverage facility air conditioning to dissipate heat from server rows, enabling localized liquid cooling for high-output data center equipment. They maximize cooling potential in air-cooled data centers, reducing thermal management equipment and installation costs while providing higher cooling capacity than air alone. Liquid to air CDUs are seen as a cost effective retrofit to bring liquid cooling technology into existing data centers without needing to upgrade the full facility's systems.

Liquid to Liquid (L2L) CDUs

Liquid to Liquid (L2L) CDUs transfer heat between two separate liquid cooling loops, requiring facility water to remove heat from rack and row equipment. Despite added system complexity, L2L CDUs offer numerous benefits. Fully liquid-cooled data centers maximize energy efficiency due to the higher heat capacity of liquid. These systems enable smaller footprints and lower total cost of ownership, making them ideal for various applications such as artificial intelligence, blockchain, mainframe servers, and supercomputers. They offer the most sustainable cooling for high powers.

CDU Liquid Cooling: Powering Efficiency and Reliability in Your Data Center

CDU liquid cooling presents a broad range of benefits essential for optimal data center performance. It ensures highly efficient and sustainable cooling by precisely targeting heat sources, enhancing equipment performance, and extending component lifespan. Data center liquid cooling's capability for precise temperature control safeguards against overheating, maintaining ideal operating conditions for servers and other critical IT equipment. CDU liquid cooling systems often integrate redundancy measures, ensuring uninterrupted operation even in the face of component failure, boosting overall reliability. These systems facilitate higher heat dissipation capacities compared to conventional air-cooling methods, enabling denser server configurations and increased computing power within the same physical footprint. With improved energy efficiency, CDU liquid cooling contributes to reduced power consumption and operational costs over time, making it a compelling choice for forward-thinking data center managers.

Empowering Data Centers: Boyd’s Cutting-Edge Liquid Cooling Solutions

Boyd's extensive +40-year expertise lies in designing liquid cooling systems, particularly CDUs, optimized for peak performance in data centers and artificial intelligence applications. Our CDUs offer advanced functionality and versatility, adaptable to various setups such as in-rack or in-row installations. With options in liquid to liquid (L2L) or liquid to air (L2A) technologies, our CDUs excel in both new installations and upgrades. Benefit from our globally redundant manufacturing capacity and trusted heritage spanning over four decades, ensuring dependable solutions. Our agile production capabilities meet demanding schedules while pushing system boundaries for exceptional results. Boyd's notable CDUs, including ROL1100-48U32, RAA32-10U21, and RAA32-10U19, are renowned for unparalleled cooling efficiency and reliability. Leveraging our engineering and material science expertise, we tailor custom cooling solutions for specific data center types. Schedule a consultation with our experts to explore our thermal management solutions and discuss your project needs.

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