TOKYO, Dec 23, 2025 - (JCN Newswire) - Mitsubishi Heavy Industries, Ltd. (MHI) and EXEO Group, Inc. have built and begun commercial use of graphics processing unit (GPU) servers efficiently cooled by two-phase direct-to-chip cooling (two-phase DLC),(1) the first such system in Japan. The location is EXEO Group's data center. GPU servers are being increasingly used in data centers due to the spread of generative AI, and the high heat generated has become a challenge. The introduction of innovative two-phase DLC addresses this problem safely.

Conventionally, the main method for cooling GPUs has been air cooling by means of a heat sink.(2) However, the latest GPUs generate heat in the 1,000 to 1,400W range, making it difficult to achieve stable cooling. The main challenges were as follows.

The first problem was that the air-cooled system could not cool the GPU sufficiently, leading to concerns about stable operation, and the potential as a factor for output limitation and failure risk. Two-phase DLC directly dissipates heat by means of a cold plate applied directly on the GPU chip, through which liquid and gaseous coolant is circulated, resulting in a heat transfer rate that is an order of magnitude higher than conventional air cooling. This enables stable operation of GPUs with high heat output, while also reducing the failure risk for the entire system.

The second issue was that single-phase liquid cooling systems had a risk of damaging the server in the event of a coolant leak. Two-phase DLC ensures safety by using non-conductive refrigerants that are electrically insulating, and so will not short circuit electrical circuits if a leak occurs, preventing damage to servers and other expensive IT equipment. The system can be used with a sense of security.

The third challenge was the increase in power consumption from fans with high air volume, as well as auxiliary cooling equipment, which tended to increase CO2 emissions. The highly efficient heat removal with two-phase DLC reduces the power usage of large fans inside the server. This improves the power factor for cooling and lowers PUE(3), reducing energy consumption and environmental impact, and curbing operating costs and the carbon footprint.(4)

EXEO Group, to ensure the high cooling efficiency and stable operation of high-performance GPU servers used for generative AI and other functions, has adopted the two-phase DLC system provided by MHI, and begun actual operation and commercial use for the first time in Japan. The combination of MHI's heating and cooling technology with EXEO Group's expertise in building and operating data centers has led to the realization of a one-stop service for GPU servers.

Going forward, the two companies will continue to accumulate technologies for system building and operations, meet the needs of continually expanding large-scale data centers, and based on the technological capabilities of both companies, provide highly reliable, one-stop solutions with low environmental impact for data center facilities, to promote green transformation (GX) in the IT sector.

(1) Two-phase DLC (Direct Liquid Cooling) uses both liquid and gaseous refrigerant, circulating coolant directly on the GPU chip to remove heat.
(2) A heat sink is a device that efficiently dissipates heat from the heat-generating components in electronic devices and machinery, curbing the temperature rise of components.
(3) Power Usage Effectiveness (PUE) is an indicator of how efficiently a data center uses power. The closer to 1.0, the greater the efficiency.
(4) Carbon footprint is a quantification of the total amount of greenhouse gases emitted directly and indirectly by individuals, companies, products, and services.

About MHI Group

Mitsubishi Heavy Industries (MHI) Group is one of the world’s leading industrial groups, spanning energy, smart infrastructure, industrial machinery, aerospace and defense. MHI Group combines cutting-edge technology with deep experience to deliver innovative, integrated solutions that help to realize a carbon neutral world, improve the quality of life and ensure a safer world. For more information, please visit www.mhi.com or follow our insights and stories on spectra.mhi.com.

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