Current Status and Challenges for Liquid-Cooled Data Centers
Frontiers in Energy Research (Frontiers Media SA) · Hongwei Chen, Dong Li
This Nanjing Normal University opinion paper classifies data-centre liquid cooling into immersion (single- and two-phase), cold plate and spray cooling, and describes the components and loop arrangement of each.
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Overview
Cooling systems are cited as consuming 30-50% of total data-centre energy; as of the end of 2017 there were 285,000 data centres in use in China, with equipment consuming more than 120 billion kWh of electricity annually (2% of China's total). The paper lists reference deployments and reported performance: IBM Power 575/775, Huawei all-liquid, Sugon immersion, Alibaba 'Kirin' and a spray-cooled container. Water's volumetric heat capacity is about 3500 times that of air and its thermal conductivity 25 times higher.
Because CDU failure can paralyse a liquid cooling system, CDU equipment should be redundant, and the circulating pump is generally arranged as one duty plus one standby. Immersion cooling can raise single-cabinet power to 100 kW or even more than 200 kW. Sugon's immersion server is reported to cut data-centre PUE to 1.05 and energy use by more than 30% versus air cooling, and Alibaba's 'Kirin' immersion server saves more than 75% of space. A lab-scale spray-cooled rack with PF5060 reduced total data-centre energy by 25.8% versus air cooling, and a spray-cooled modular container reached an IT load of 284 kW.
The authors expect cold plates to dominate in the near term because they need little server adaptation, judge immersion currently applicable only to new data centres, find spray cooling still lab-stage with coolant evaporation and escape risk, and highlight heat recovery from warmer coolant as a key opportunity.
Limits: a short opinion paper; all figures are cited from earlier literature with no new measurements, and reported gains come from different conditions and cannot be compared directly.
Key points
- Cooling systems are cited as consuming 30-50% of total data-centre energy.
- Water's volumetric heat capacity is about 3500 times that of air and its thermal conductivity 25 times higher.
- Because CDU failure can paralyse a liquid cooling system, CDU equipment should be redundant, and the circulating pump is generally one duty plus one standby.
- Immersion cooling can raise single-cabinet power to 100 kW or even more than 200 kW.
- Sugon's immersion server is reported to cut data-centre PUE to 1.05 and energy use by more than 30% versus air cooling, and Alibaba's 'Kirin' immersion server saves more than 75% of space.
- A lab-scale spray-cooled rack with PF5060 reduced total data-centre energy by 25.8% versus air cooling, and a spray-cooled modular container reached an IT load of 284 kW.
- Immersion is judged currently applicable only to new data centres, while spray cooling risks coolant evaporation and escape and remains lab-stage.
Using it in design
- Design the CDU as redundant in liquid cooling and arrange the circulating pump as one duty plus one standby; a CDU failure can paralyse the whole system.
- Compare cold plates (little server adaptation) for existing data centres and immersion for new builds as options; note spray cooling as a lab-stage technology.
- Treat heat recovery from warmer coolant as an opportunity item in liquid cooling design.
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Who should read it
Cooling designers and decision makers comparing liquid cooling technologies (immersion, cold plate, spray).
Document contents
- 1 Introduction
- 2 Current Research Status of Liquid-Cooled DCs (2.1 Classification of Liquid Cooling Technology: immersion liquid cooling, cold plate liquid cooling, spray liquid cooling; 2.2 Application of Liquid Cooling)
- 3 Opportunities and Challenges
- 4 Conclusion
Related standards
- OCP Advanced Cooling Solutions (immersion)
Read the document
liquid-cooled-dc-status-challenges-2022.pdf
CC BY 4.0 — share with attribution
The document is provided unaltered because its licence permits redistribution.
Publication details
- Authors
- Hongwei Chen; Dong Li
- Publisher
- Frontiers in Energy Research (Frontiers Media SA)
- Year
- 2022
- Volume
- 10
- Pages
- 952680
- Document language
- English
- Source type
- Scientific
- Access
- Open licence — downloadable
- Licence
- CC BY 4.0 — share with attribution
- Licence evidence
- doi.org
Original licence note
Article states it is open access under a Creative Commons Attribution (CC BY / CC BY 4.0) licence (verified in PDF text).
Citation
Hongwei Chen; Dong Li (2022). Current Status and Challenges for Liquid-Cooled Data Centers. Frontiers in Energy Research (Frontiers Media SA). 10, 952680. https://doi.org/10.3389/fenrg.2022.952680
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