Data Center Liquid Cooling 101

As rack densities in data centers increase to support power-hungry applications like Artificial Intelligence and high-performance compute (HPC), data center professionals struggle with the limited cooling capacity and energy efficiency of traditional air cooling systems.

In response, a potential solution has emerged in liquid cooling, a paradigm shift from traditional air-based methods that offers a more efficient and targeted approach to thermal management.

The data center liquid cooling market is expected to grow by over 24% annually over the next five years as organizations seek ways to support high-density infrastructure and meet sustainability objectives.

Keep reading to learn the basics about liquid cooling and see if it’s something you should be considering in your data center.

The Need for Efficient Cooling in Data Centers

Modern data centers are witnessing a remarkable increase in power density, driven by advancements in computing technologies. Whereas the average rack density was 4-5 kW a decade ago, it is now predicted to be as high as 15-20 kW in a few years.

Servers are becoming more powerful, packing increased processing capabilities into smaller physical spaces. While this surge in performance is a technological triumph, it comes at the cost of heightened heat generation. The concentrated power within server racks necessitates innovative cooling solutions to maintain optimal operating temperatures.

Temperature plays a pivotal role in determining the performance and longevity of hardware within data centers. Excessive heat can lead to reduced efficiency, performance throttling, and even permanent damage to critical components leading to downtime. Therefore, mitigating the impact of high temperatures on hardware is a top priority for data center operators.

Inefficient cooling not only jeopardizes the health of hardware but also contributes significantly to energy consumption and operational costs. Traditional air cooling methods, while widely used, face limitations in effectively dissipating the intense heat generated by some modern servers. Consequently, data centers often resort to overprovisioning air conditioning systems, leading to increased energy consumption and operational expenses. Alternatively, large amounts of cabinet space must be left unused so that the temperature does not get too high. This stranded capacity is a waste of money and resources.

Therefore, liquid cooling emerges as a promising alternative, addressing some of the challenges posed by high power density and heat generation.

What is Data Center Liquid Cooling?

Data center liquid cooling is the use of a liquid coolant to absorb and transfer heat away from electronic components, such as processors and memory modules, within servers. Unlike air cooling, which relies on the circulation of air to dissipate heat, liquid cooling systems provide a direct and more efficient means of carrying away thermal energy. The principles of liquid cooling leverage the high heat capacity and superior thermal conductivity of liquids to maintain optimal operating temperatures.

Types of Data Center Liquid Cooling Systems

Data center liquid cooling comes in various forms, each designed to meet specific needs and preferences. Three prominent types of liquid cooling systems are:

• Direct-to-chip cooling. Direct-to-chip cooling involves circulating liquid coolant directly over the heat-generating components of individual chips. It ensures precise and targeted cooling, efficiently removing heat at its source.
• Immersion cooling: Immersion cooling submerges entire servers or hardware components in a dielectric fluid, creating a direct and uniform cooling effect. This method minimizes the need for intricate cooling infrastructure and promotes enhanced thermal efficiency.
• Rear-door liquid cooling. This system draws ambient air into the cabinet, removes heat using radiator-like doors attached to the back of the rack, and reintroduces the cooled air into the room. Removing heat closer to the source than air cooling results in greater efficiency.

Data Center Liquid Cooling vs. Air Cooling

As the demand for efficient data center cooling solutions intensifies, the choice between liquid cooling and traditional air cooling methods has become a major consideration for many organizations.

Key considerations in favor of liquid cooling include:

• Heat removal. Liquid cooling systems excel in efficiently dissipating heat due to their direct contact with heat-generating components. Unlike air, which has lower thermal conductivity, liquid coolant can absorb and carry away heat up to four times more effectively. This direct contact allows for precise temperature control, preventing hotspots, and ensuring even cooling across all components.
• Temperature control precision. Liquid cooling systems offer superior precision in temperature control. The ability to tailor the cooling process to the specific needs of individual components ensures that they operate within optimal temperature ranges. In contrast, air cooling, while effective to a certain extent, may struggle to maintain consistent temperatures, especially in high-density environments.
• Energy efficiency. One of the primary advantages of liquid cooling is its higher energy efficiency compared to air cooling. By removing heat more efficiently, liquid cooling systems reduce the workload on traditional air conditioning units, leading to up to 90% energy savings. This efficiency is particularly crucial in the quest for sustainable and environmentally friendly data center solutions.
• Rack density. Liquid cooling's ability to effectively manage heat enables data center operators to explore higher rack densities without compromising performance. This is particularly advantageous in environments where space optimization is a critical consideration.
• Space utilization. Liquid cooling systems often have a smaller footprint compared to air cooling infrastructure. This compact nature allows for better space utilization within data centers, accommodating more hardware while maintaining efficient thermal management.
• Maintenance requirements. Liquid cooling systems generally exhibit lower maintenance requirements compared to traditional air cooling setups. The absence of dust and debris in liquid-cooled environments reduces the risk of component damage, and the closed-loop nature of many liquid cooling systems minimizes the need for frequent maintenance interventions.
• Reliability. The enhanced thermal management provided by liquid cooling contributes to the overall reliability of data center operations. Reduced susceptibility to overheating ensures that hardware components operate within their specified parameters, minimizing the risk of unexpected downtime.

Key Components of Data Center Liquid Cooling Systems

To comprehend the inner workings of liquid cooling systems and appreciate their efficiency, it is important to know the key components that make up these systems. Each element plays a crucial role in ensuring optimal thermal management within data centers.

• Coolants. The heart of any liquid cooling system lies in its choice of coolant. Coolants, also known as heat transfer fluids, circulate through the system, absorbing and carrying away heat from electronic components. Common coolants include dielectric fluids, mineral oil, or specially formulated liquids. The choice of coolant depends on factors such as thermal conductivity, compatibility with materials, and environmental considerations.
• Heat exchangers. Heat exchangers form a pivotal component in liquid cooling systems, facilitating the transfer of thermal energy from the coolant to an external medium, usually air or another liquid. These devices play a crucial role in dissipating heat efficiently, ensuring that the coolant returns to the system at a lower temperature, ready to absorb more heat from the electronic components.
• Pumps. Pumps are the workhorses of liquid cooling systems, ensuring the continuous circulation of coolant throughout the system. By maintaining a steady flow, pumps enable efficient heat transfer and prevent the formation of stagnant zones that could lead to uneven cooling. The design and efficiency of pumps significantly impact the overall performance of the liquid cooling setup.
• Containment systems. Given the use of liquids in close proximity to sensitive electronic components, containment systems are critical to prevent leaks and ensure the safety of the data center environment. These systems include seals, barriers, and reservoirs designed to contain the coolant within the prescribed pathways. Rigorous testing and engineering are employed to minimize the risk of leaks and protect hardware from potential damage.

Challenges and Considerations for Data Center Liquid Cooling

While the adoption of liquid cooling technology provides several advantages, it is crucial to acknowledge and address the associated challenges as well. A comprehensive understanding of the pros and cons is essential for organizations contemplating the shift to liquid cooling in their data centers.

• Complexity of implementation. The integration of liquid cooling systems can be complex, requiring careful planning and execution. The intricacies involved in retrofitting existing data center infrastructure or designing new facilities with liquid cooling in mind can pose challenges for organizations unfamiliar with the technology.
• Risk of leaks. While containment systems are in place to prevent leaks, the risk of coolant escaping and coming into contact with electronic components remains a concern. Organizations must implement stringent safety measures, conduct regular inspections, and choose reliable components to mitigate this risk.
• Compatibility with hardware. Ensuring compatibility between liquid cooling systems and existing or planned hardware is paramount. Not all servers are designed to accommodate liquid cooling solutions, and organizations must verify that their chosen systems can seamlessly integrate with the selected liquid cooling technology.
• Space and layout constraints. The retrofitting of existing data centers to accommodate liquid cooling may face challenges related to space and layout constraints. The compact nature of liquid cooling systems might require adjustments to rack configurations and overall facility design.
• Plumbing and piping infrastructure. Installing the necessary plumbing and piping infrastructure for liquid cooling involves modifications to the data center layout. Proper planning is essential to ensure that the plumbing components do not interfere with existing hardware and that the overall system maintains reliability.
• Additional power requirements. While liquid cooling systems can lead to energy savings in terms of overall data center cooling, it's important to consider potential additional power requirements. Pumps and other components integral to liquid cooling setups may introduce an additional power load, necessitating adjustments to power distribution plans.
• Cooling fluid disposal. The disposal of cooling fluids, especially if they are non-biodegradable or potentially harmful, raises environmental concerns. Organizations must adopt environmentally responsible practices for the handling and disposal of cooling fluids to minimize their impact on ecosystems.
• Energy intensity of production. The production and manufacturing of certain liquid coolants and components can be energy-intensive. Organizations committed to sustainability must weigh the environmental impact of the entire lifecycle of liquid cooling systems, from production to operation.
• Carbon footprint considerations. While liquid cooling can contribute to energy efficiency within the data center, organizations should conduct a comprehensive analysis of the overall carbon footprint, including the energy required for manufacturing and the potential environmental impact of the chosen cooling technology.

Integrating DCIM Software for High-Density Infrastructure Management

As data centers evolve to meet the demands of high-density computing and implement advanced cooling technologies, the integration of Data Center Infrastructure Management (DCIM) software becomes instrumental in ensuring efficient operations.

DCIM software provides real-time data center monitoring and management of data center operations, playing a central role in optimizing the efficiency of data centers.

DCIM software simplifies high-density infrastructure management with:

• Real-time monitoring of power and environment. Modern DCIM software can monitor over 10 billion data points a day from power meters and environment sensors and help you stay ahead of potential issues by setting warning and critical thresholds on power loads, three-phase balance, rack PDU circuit breaker state change, temperature, and humidity. Then, you can receive automatic alerts upon threshold violations to proactively resolve problems. Identify and prevent hot spots by utilizing thermal map time-lapse videos and ASHRAE psychrometric cooling charts to ensure cabinets stay within manufacturer- and industry-accepted thermal guidelines.
• More informed capacity planning. Effortlessly understand power capacity and load at each point in your power chain and ensure new loads won’t trip breakers, balance phases, and ensure redundancy. Safely deploy more servers in existing cabinet resources with automatic server power budgeting, proven to unlock 40% more capacity. Use what-if analysis to know the impact of planned projects on rack power and space capacity, find the optimal cabinet space for new equipment in seconds and reserve all resources with a click, and project future power capacity needs to stay ahead of potential bottlenecks.
• Highly productive high-density infrastructure management. 250+ out-of-the-box dashboard charts and reports make it easy to track high-density KPIs like capacity and utilization of power, space, cooling, and data/power port connections, delta T per cabinet, energy cost, and Power Usage Effectiveness (PUE). Visualize your high-density racks and cabling on a 3D floor map with overlaid power and environmental data and see how they connect with complete network diagrams of active and passive components. Leverage out-of-the-box connectors to seamlessly integrate with your CMDB, ticketing, and Dev Ops tools to drive data center automation that reduces manual effort and increases the accuracy of information.

Future Trends in Data Center Liquid Cooling

Liquid cooling is poised for further advancements shaped by emerging technologies, industry demands, and a collective push towards sustainability.

Likely trends in data center liquid cooling include:

• Advanced coolant formulations. Future liquid cooling systems are likely to witness the development of advanced coolant formulations with improved thermal conductivity, non-conductivity, and environmental sustainability. The quest for more efficient coolants that contribute to enhanced heat transfer and system reliability is expected to drive ongoing research and development efforts.
• Integration of AI. The integration of AI into liquid cooling management systems is on the horizon. AI algorithms can analyze vast datasets in real-time, predicting temperature fluctuations, optimizing cooling strategies, and identifying potential issues before they escalate. This proactive approach to cooling management aligns with the broader industry trend towards predictive analytics and smart data center operations.
• Two-phase liquid cooling systems. Two-phase liquid cooling systems, which use the phase transition of coolant to vapor for efficient heat dissipation, are gaining traction. These systems offer the potential for even higher heat transfer rates, making them suitable for applications with extremely high power densities.
• Edge computing and liquid cooling. The rise of edge computing, where data processing occurs closer to the source of data generation, is influencing the adoption of liquid cooling in smaller, distributed data centers. Liquid cooling's ability to manage heat efficiently in compact spaces makes it well-suited for edge computing environments where traditional cooling methods may be impractical.
• Increased focus on sustainability. Sustainability is a driving force in the future of data center technologies, including liquid cooling. Efforts to minimize environmental impact through the use of eco-friendly coolants, energy-efficient designs, and closed-loop systems are expected to become more prominent. Liquid cooling solutions that align with corporate sustainability goals will gain favor.
• Dynamic cooling control systems. Future liquid cooling systems may feature dynamic cooling control systems that adjust cooling intensity based on real-time demands. These adaptive systems can optimize energy usage, respond to workload fluctuations, and ensure that cooling resources are allocated precisely where and when needed.
• Integration of liquid cooling with renewable energy. A growing emphasis on renewable energy sources in data centers may lead to the integration of liquid cooling systems with renewable energy technologies. This synergy could enhance the overall sustainability of data center operations by reducing reliance on traditional power grids.
• Standardization and interoperability. As liquid cooling becomes more prevalent, industry standardization and interoperability will likely gain importance. Standardized interfaces and protocols can promote compatibility between different liquid cooling components and systems, allowing for easier integration and maintenance.

Bringing It All Together

The escalating power densities in modern data centers demand innovative cooling solutions. Traditional air cooling faces limitations, leading to increased energy consumption and operational costs.

The emergence of liquid cooling provides a promising alternative, addressing challenges associated with high power density and heat generation. Liquid cooling excels in heat dissipation, temperature control precision, and energy efficiency but comes with challenges like complexity, potential leaks, and compatibility with existing systems.

As the industry evolves, standardization and interoperability will likely play a crucial role in the widespread adoption of liquid cooling technologies. For data center professionals, understanding and embracing liquid cooling may prove instrumental in meeting the demands of high-density computing while advancing sustainability goals.

Want to see how Sunbird’s modern DCIM software simplifies high-density infrastructure management? Get your free test drive today.