What is the Innovative Cooling Systems for Tackling Data Center Heat Issues?

The Importance of Cooling Systems in Data Centers

Data centers are the core of modern information infrastructure, processing and storing huge amounts of data. However, the concentration of high-performance servers and equipment also generates large amounts of heat. If not properly managed, this heat can seriously affect the deterioration and failure of equipment and the stability of operations. For this reason, cooling systems in data centers are no longer merely ancillary equipment, but an essential element for ensuring the reliability and efficiency of operations.

Cooling system power consumption

The power consumption required for cooling a data center accounts for a non-negligible proportion of the total power consumption. In conventional data centers, servers consume approximately 50% of the power, power supplies and cooling systems consume 25-30%, and storage consumes around 10%.

However, the introduction of high-performance servers has also increased the amount of electricity required for cooling. This power consumption not only increases the operating costs of data centers, but also poses a major issue in terms of the environmental impact.

What is an immersion cooling system?

Immersion cooling is an innovative system that cools IT equipment such as servers by directly immersing them in a cooling liquid. This method uses a special cooling liquid with high thermal conductivity, which allows heat to be removed more efficiently than conventional air cooling methods.

Conventional data center cooling systems (air-cooling systems and water-cooling systems)

Conventional data centers mainly use air-cooling systems, which send large amounts of cold air throughout the server room to cool the equipment. Water-cooling systems are also used in some data centers, which use pipes to transport cooling water close to the equipment and perform heat exchange.

Principles of immersion cooling devices (single-phase and two-phase)

There are two main types of immersion cooling equipment: single-phase and two-phase.

Single Phase Immersion Cooling

In the single-phase system, a coolant with a boiling point above 100°C is used, and cooling is performed while maintaining the liquid state. The coolant absorbs heat from electronic components, passes through a heat exchanger to be cooled, and then returns to the cooling tank, forming a circulation cycle.

Two-phase immersion cooling

The two-phase system uses a coolant with a low boiling point. This system utilizes a phase change in which the coolant absorbs heat from the electronic components and evaporates, and the vapor is cooled in the condenser and returns to a liquid. This process utilizes latent heat, which allows for higher cooling efficiency.

Comparison with conventional cooling systems

Immersion cooling offers the following advantages over traditional air cooling systems:

1. High cooling efficiency: Liquids have a higher thermal conductivity than air, so they can remove heat more efficiently.
2. Reduced energy consumption: In KDDI's demonstration experiment, a 94% reduction in power consumption was achieved compared to air-cooling.
3. Space saving: The smaller size of the cooling equipment allows for more efficient use of data center installation space.
4. Quiet operation: With no need for fans or large air conditioning systems, operation noise is significantly reduced.
5. High density support: Effective cooling is possible even in high-density environments where power consumption per rack exceeds 15 kilowatts.

Challenges in implementation

The implementation of immersion cooling presents several challenges:

1. Initial implementation costs: Coolants and dedicated equipment are expensive, so initial investments tend to be large.
2. Compatibility with existing systems: Legacy equipment may not be usable as is and adaptations are required.
3. Maintenance: Maintenance work can be complicated due to the liquid involved.
4. Support for optical connections: Conventional optical cables and optical modules have been difficult to use in liquid immersion environments, but companies such as Accelink are developing optical modules that are compatible with liquid immersion. There are also companies currently developing optical connectors.

summary

Datacenter cooling technology is evolving rapidly. Immersion cooling systems have been attracting attention as an innovative solution that achieves high cooling efficiency and significant reductions in energy consumption. However, there are several challenges to its introduction, such as initial costs and compatibility with existing systems.

As demand for data centers continues to expand and density continues to increase, immersion cooling devices are expected to play an increasingly important role. As technology advances, solutions to problems will also progress, and it is expected that the adoption of immersion cooling devices in more data centers will contribute to improving energy efficiency and reducing the environmental impact.

Reference information

• The impact of the development of the information society on energy consumption (Vol. 2) - Current status and future predictions of energy consumption in data centers and technical issues - (Center for Low Carbon Society Strategy, Japan Science and Technology Agency, February 2020)
• Immersion Cooling: The Ultimate Cooling Solution for Data Centers-2 (UniPo Corporation)
• NTT Technology Journal "Next-generation Data Center Project Contributing to Carbon Neutrality" (January 2025)
• KDDI Corporation, "Liquid cooling of servers in data centers achieves 94% reduction in cooling power" (Open Compute Project Japan, June 2023)
• Green Revolution Cooling, Inc. ‘Two-Phase Versus Single-Phase Immersion Cooling’, November 13, 2019