Glance Foundry

Liquid cooling overview

Liquid cooling: from chips to data centers

How heat moves from processors to the facility, why liquid cooling is expanding, and where thin films and thermal interfaces fit. Explore the cooling approaches, their history, and the investment behind them.

01 / 07

Cooling limits computing density

Cooling limits how much computing power fits in a space.6,7

Three measures matter

Component power
Power of one accelerator or module.6,10
Rack power
The cabinet’s combined electrical load.6,10
Heat flux
Heat flow per unit area. Concentrated hot spots can be difficult to cool even when total power seems manageable.9,11

Air cooling has no universal rack-power cutoff

The crossover depends on airflow, equipment, operating conditions, and cost.15 In a 2025 survey, 20–29 kW was the most common estimate for when direct liquid cooling becomes necessary, chosen by 25% of respondents.16

02 / 07

Why liquid cooling is expanding

Higher accelerator power and dense, interconnected racks make cooling a package, rack, and facility problem.6,8

Published rack figures

ExampleFigureWhat it describes
2024 reference design120 kWCooling capacity.44
Published rack datasheet132–140 kWSpecified operating power.45
AI blueprint available by November 2026227 kWCooling design capacity.46
From 2027; roadmap announced May 20251 MWPower-distribution target.47

Cooling capacities, equipment power specifications, and roadmap targets describe different limits.44,45,46,47

In Uptime’s 2025 survey, 22% of the 512 respondents to the cooling-type question reported using direct liquid cooling.16

Annual data-center electricity use

United States

Berkeley Lab · December 2024 report3

2018 Estimate
76 TWh/year
2023 Estimate
176 TWh/year

Worldwide

International Energy Agency · April 2026 update48

2025 Estimate
485 TWh/year
2030 Projection
about 950 TWh/year
These figures cover all data centers, not AI alone.3,48

Energy efficiency and water

Power usage effectiveness (PUE) divides total facility energy by IT equipment energy.14 It does not measure useful computing output or water consumption.3,14

For 2023, Berkeley Lab estimated U.S. data-center water consumption at 66 billion liters on site, plus nearly 800 billion liters associated with electricity generation.3

03 / 07

Inside a cold-plate cooling loop

In a cold-plate system, heat crosses the processor package and cooling interfaces into a sealed heat exchanger with internal coolant channels.8,15 The single-phase example below keeps the coolant liquid as it warms.17

Equal heat capacity

1 L of water≈3,600 L of air

For the same temperature rise

Near room temperature, these volumes absorb approximately the same heat for the same temperature rise.7,18

Getting heat into the coolant

The heat-transfer coefficient h describes heat transfer from the surface into the moving coolant.9 It depends on flow, channel geometry, and coolant properties.11

Single-phase cooling relationships

Heat carried by single-phase coolant

Q˙=m˙⁢cp⁢(Tout−Tin)7

Heat transferred from the surface

Q˙=h⁢A⁢ΔTsurface−fluid7

Q˙
Heat-transfer rate (W)
m˙
Coolant mass flow rate (kg/s)
cp
Coolant specific heat capacity (J/(kg·K))
Tout−Tin
Coolant temperature rise (K)
h
Surface-to-fluid heat-transfer coefficient (W/(m²·K))
A
Heat-transfer area (m²)
ΔTsurface−fluid
Appropriate surface-to-fluid temperature difference (K)

The first equation describes single-phase coolant warming. Its inlet-to-outlet temperature rise differs from the surface-to-fluid temperature difference in the second equation.7

Two separate circuits

A coolant distribution unit (CDU) commonly circulates the electronics coolant and transfers its heat to a separate facility water loop.19 The electronics loop can then use its own pressure and coolant chemistry.19

Example: a single-phase cold-plate loop

Electronics loopFacility water loopReturn / supplyHeat transferHeat exchangerPumpFacility pumpDry-cooling exampleHeat recovery,where usefulHeatWarm coolant to CDUCooled coolant to cold platesWarm facility waterCooled facility waterProcessor cold plateRack manifoldsCoolant distributionunit (CDU)Facility waterBuilding coolingElectronics loopProcessor cold plateRack manifoldsWarm returnCooled supplyPumpHeattransferHeat exchangerCoolant distribution unit (CDU)Facility water loopCooled facilitywaterWarm facilitywaterFacility pumpBuilding coolingHeat recovery, where useful

Building cooling: Dry cooling or Cooling tower5

↳ Heat recovery, where useful21

The CDU transfers heat while the electronics and facility coolants remain separate.19

Where the heat goes

Liquid cooling at the chip does not automatically require evaporation at the site.5,20 The building may use dry cooling or cooling towers.5 Heat can also be recovered when another building or process needs it at a suitable temperature.21

04 / 07

Liquid cooling approaches

Cooling approaches differ in where liquid collects heat and whether it changes phase.17

Coolant inWarm coolant outProcessor package

Cold plates

Coolant flows through sealed plates on processor packages.15,17

Single-phase designs often retain some air cooling.15

Electrically insulating liquidSubmerged electronics

Immersion

Electronics sit in electrically insulating liquid.15,17

Fluid compatibility and servicing shape the system.8,17

Server exhaust air →ReturnSupply

Rear-door heat exchangers

A water-cooled coil captures server exhaust heat.5

Server fans and heat sinks remain.5

Phase options for cold plates and immersion

  • Single-phase

    Coolant stays liquid. In immersion, an exchanger removes heat from the warmed bath.17

  • Two-phase

    Coolant boils and later condenses.17,22 In immersion, condensate returns to the bath.17 Two-phase cold plates must manage boiling stability and dryout.11

Local cooling techniques

  • Embedded microfluidics

    Example: channels in siliconHeat transferSiliconCoolant channelCoolant flow →

    Coolant flows through channels in or near the silicon.7,23

  • Jet impingement

    Jet impingementHeated surfaceLiquid outLiquid outNozzle

    Small coolant jets target a heated surface to improve local heat transfer.17

05 / 07

Six decades of liquid cooling

Selected milestones, 1964–2026.

  1. Mainframes and early research
  2. 1964–1965

    Water-cooled mainframes

    IBM announced water-cooled heat exchangers between board stacks in 1964; a separate computer-water circuit followed in 1965.54

  3. 1980

    Water-cooled chip packages

    Thermal conduction modules carried heat from multiple chips to a water-cooled plate.54,56

  4. 1981

    Silicon microchannels

    Tuckerman and Pease demonstrated water cooling through silicon microchannels.7

  5. 1985

    Immersion in supercomputing

    Cray-2 cooled its submerged electronics with an electrically insulating liquid.57

  6. 1994–1995

    Air cooling returns

    Lower-power CMOS processors helped IBM mainframes return to air cooling.54,56

  7. Rack cooling and heat reuse
  8. 2005

    Cooling server exhaust

    Rear-door heat exchangers captured server exhaust heat in water while the electronics remained air-cooled.54

  9. 2010–2012

    Warm-water supercomputing

    In 2010, ETH Zurich’s Aquasar used cooling water up to 60°C and supplied heat for the building.21 SuperMUC opened in 2012 with inlet water up to 40°C.55

  10. AI deployment and new research
  11. 2018

    Liquid-cooled AI accelerators

    Google deployed liquid cooling for its TPU v3 AI accelerators.24

  12. 2025
    Prototype

    Cooling through the back of a chip

    Microsoft announced a microfluidic prototype with coolant channels etched into the back of a chip.23

  13. 2026
    Validation target

    A 1 MW cooling target

    COOLERCHIPS 1.5 set a goal to validate cooling systems against heat loads of 1 MW per rack.61

06 / 07

Investment in cooling

Three kinds of capital

Public support
Research and validation.4,61
Private financing
Product development, manufacturing, and expansion.22,62,66,67
Acquisitions
Purchases of operating businesses and their capabilities.63,64

The amounts below do not measure total spending on cooling research.4,63,64

Selected funding and acquisition events

Nominal U.S. dollars · logarithmic chart scale

Nominal U.S. dollars · log scale$10M$100M$1B$10BPublic supportMay 2023COOLERCHIPSFunding selection; 15 projects$40MNov 2024Akash Systems · proposedProposed maximum; nonbinding preliminary termsUp to $18.2MPrivate financingOct 2023JetCool · Series ASeries A announced$17MSep 2024LiquidStack · extensionSeries B extension$20MOct 2024SubmerSecured to date at announcement$55.5MSep 2025Corintis · Series ASeries A announced$24MDec 2025Corintis · separate roundSeparate financing$25MJan 2026AccelsiusSeries B closing announced$65MMay 2026Iceotope · Series BSeries B announced$26MJun 2026ZutaCore · Series CSeries C; release-body amount$100MAcquisitionsOct 2024Motivair · 75% stake75% stake; announced agreement$850MNov 2024Flex / JetCoolEstimated total consideration$52MMar 2026Boyd ThermalCompleted; net of acquired cash$9.55B
TypeEventAmountWhat the amount represents
Public supportU.S. Department of Energy / COOLERCHIPS (May 2023)US$40 millionFunding announced for 15 selected research projects.4
Public supportCHIPS / Akash Systems (November 2024)Up to US$18.2 million proposedProposed direct funding under nonbinding preliminary terms for diamond-based semiconductor manufacturing.69
Private financingJetCool (October 2023)US$17 millionSeries A financing led by Bosch Ventures for development and expansion.65
Private financingLiquidStack (September 2024)US$20 millionSeries B extension from Tiger Global for manufacturing and cooling research; part of a US$35 million cumulative Series B.66
Private financingSubmer (October 2024)US$55.5 millionGrowth financing secured to date; led by M&G Catalyst.67
Private financingCorintis (September 2025)US$24 millionSeries A led by BlueYard Capital for chip-cooling development and commercialization.62
Private financingCorintis (December 2025)US$25 millionSeparate financing round led by Applied Digital for chip-cooling development.70
Private financingAccelsius (January 2026)US$65 millionSeries B closing announced; Johnson Controls led, with Legrand investing.22
Private financingIceotope (May 2026)US$26 millionSeries B led by Two Seas Capital and Barclays Climate Ventures for development and deployment.71
Private financingZutaCore (June 2026)US$100 millionSeries C financing for two-phase cooling commercialization; the release body states US$100 million.72
AcquisitionsSchneider Electric / Motivair (October 2024 agreement)US$850 millionAnnounced price for a 75% stake; the deal closed in February 2025.68,79
AcquisitionsFlex / JetCool (November 2024)US$52 million estimatedCompleted acquisition; estimated total consideration includes cash, loan settlement, and contingent consideration.64
AcquisitionsEaton / Boyd Thermal (March 2026)US$9.55 billionCompleted acquisition of a broad thermal-management business; price is net of acquired cash.63

07 / 07

Thin films and thermal interfaces

Solid layers and contacts between the chip and coolant add thermal resistance.7,8 Reducing resistance on the fluid side increases their share of the total if they remain unchanged.7

Thermal interface materials help heat cross adjoining surfaces; solder can form a bonded metal interface.8,86

Thin-film roles

RoleWhat it does
Joint surfacesMetal finishes influence how solder joints form and age.86
Diffusion barriersNickel can limit copper–tin interdiffusion; its effect depends on the layer stack and thermal history.86
Test heatersDeposited thin-film resistors provide controlled heat input in cooling experiments.7

Thermal performance, flow, packaging, and long-term reliability must be evaluated together.8,60,86

Sources

  1. 1AMD (2025). Fourth-generation compute architecture white paper [equipment identifier omitted]. Manufacturer white paper.
  2. 3Lawrence Berkeley National Laboratory (2024). 2024 United States Data Center Energy Usage Report. LBNL.
  3. 4US Department of Energy (2023). DOE Announces $40 Million for More Efficient Cooling for Data Centers. DOE / ARPA-E.
  4. 5ASHRAE (2023). 2023 ASHRAE Handbook — HVAC Applications, Chapter 20: Data Centers and Telecommunication Facilities.
  5. 6International Energy Agency (2026). Key Questions on Energy and AI. IEA.
  6. 7David B. Tuckerman and R. F. W. Pease (1981). High-Performance Heat Sinking for VLSI. IEEE Electron Device Letters.
  7. 8Open Compute Project (2023). OAI System Liquid Cooling Guidelines. OCP.
  8. 9Yunus A. Çengel (2003). Heat Transfer: A Practical Approach, second edition. McGraw-Hill; accessible textbook transcription.
  9. 10NVIDIA (2016). Socketed accelerator datasheet, 2016 generation [equipment identifier omitted]. Manufacturer datasheet.
  10. 11Junqiang Zhang, Zhengping Zou and Chao Fu (2023). A Review of the Complex Flow and Heat Transfer Characteristics in Microchannels. Micromachines.
  11. 12NVIDIA (2025). Accelerator architecture technical brief, 2024–2025 generations [equipment identifiers omitted]. Manufacturer technical brief.
  12. 13NVIDIA (2016). 2016 accelerator introduction [equipment identifier omitted]. NVIDIA Newsroom.
  13. 14Uptime Institute (2026). Uptime Institute Global Data Center Survey 2026.
  14. 15Jessica Gullbrand, Nigel Gore, Jason Matteson and Elizabeth Langer (2019). ACS Liquid Cooling Cold Plate Requirements Document, revision 1.0. Open Compute Project.
  15. 16Uptime Institute (2025). Uptime Institute Cooling Systems Survey 2025: DLC adoption remains slow and steady. Uptime Institute Intelligence.
  16. 17Sijun Xu, Hua Zhang and Zilong Wang (2023). Thermal Management and Energy Consumption in Air, Liquid, and Free Cooling Systems for Data Centers: A Review. Energies.
  17. 18Dale Sartor (2012). PG&E/FEMP Data Center Efficiency Workshop. Lawrence Berkeley National Laboratory / FEMP.
  18. 19Open Compute Project contributors. Liquid Cooling Integration and Logistics White Paper, revision 1.0. OCP.
  19. 20Microsoft (2024). Sustainable by design: Next-generation datacenters consume zero water for cooling. Microsoft Cloud.
  20. 21HPC-CH; ETH Zurich and IBM (2010). Warm-water research computer announcement [equipment identifier omitted]. HPC-CH.
  21. 22Accelsius (2026). Accelsius Closes $65 Million Series B Funding Led by Johnson Controls; Legrand Joining Round. Company release via Business Wire / Nasdaq.
  22. 23Microsoft (2025). Microsoft microfluidic cooling research announcement [equipment identifiers omitted]. Microsoft Source.
  23. 24Madhusudan Iyengar and Amber Huffman; Google (2025). Enabling 1 MW IT racks and liquid cooling at OCP EMEA Summit. Google Cloud.
  24. 44NVIDIA (2024). Open rack-scale architecture contribution [equipment identifiers omitted]. NVIDIA Technical Blog.
  25. 45Hewlett Packard Enterprise (2025). Liquid-cooled rack data sheet, 2025 generation [equipment identifier omitted]. Manufacturer datasheet.
  26. 46Super Micro Computer, Inc.. Rack-scale liquid-cooling solution blueprints [equipment identifiers omitted]. Manufacturer product specifications.
  27. 47Mathias Blake et al.; NVIDIA (2025). 800 VDC Architecture Will Power the Next Generation of AI Factories. NVIDIA Technical Blog.
  28. 48International Energy Agency (2026). Key Questions on Energy and AI — Executive summary. IEA.
  29. 54Roger R. Schmidt (2005). Liquid Cooling is Back. Electronics Cooling.
  30. 55Leibniz Supercomputing Centre (2014). 2014 results report for a warm-water HPC installation [equipment identifier omitted]. LRZ.
  31. 56M. Y. Lanzerotti, G. Fiorenza and R. A. Rand (2005). Microminiature packaging and integrated circuitry: The work of E. F. Rent, with an application to on-chip interconnection requirements. IBM Journal of Research and Development.
  32. 57Cray Research (1985). 1985 immersion-cooled supercomputer brochure [equipment identifier omitted]. Computer History Museum archive.
  33. 60TSMC (2021). Packaging Technologies for Chiplets and 3D. Hot Chips 33.
  34. 61US Department of Energy, Office of NEPA Policy and Compliance (2026). CX-271071: COOLERCHIPS 1.5 Program. DOE.
  35. 62Corintis (2025). Corintis Raises $24M to Target the Next AI Bottleneck and Collaborates with Microsoft for Chip Cooling Breakthrough. Company release via GlobeNewswire.
  36. 63Eaton Corporation plc (2026). First Quarter 2026 financials. Eaton investor relations.
  37. 64Flex Ltd. (2025). Flex quarterly report for period ended December 31, 2024. SEC.
  38. 65Bosch Ventures (2023). Bosch Ventures leads investment in JetCool. Bosch press release.
  39. 66LiquidStack (2024). LiquidStack Secures $20 Million from Tiger Global.
  40. 67Submer (2024). Submer growth round for greener AI factories and datacenters.
  41. 68Schneider Electric (2024). Third Quarter 2024 Revenues presentation. Investor relations.
  42. 69NIST / CHIPS for America (2024). Biden-Harris Administration Announces Preliminary Terms with Akash Systems. US Department of Commerce.
  43. 70Applied Digital (2025). Applied Digital Leads $25 Million Funding Round for Corintis. Investor relations.
  44. 71Iceotope (2026). Iceotope raises $26m.
  45. 72ZutaCore (2026). ZutaCore $100M Series C Funding for AI Data Center Cooling.
  46. 75ARPA-E. COOLERCHIPS Project Descriptions. US Department of Energy.
  47. 79Schneider Electric (2025). 2025 Half Year Financial Results Accounts. Investor relations.
  48. 86Mohd Izrul Izwan Ramli et al. (2022). Formation and Growth of Intermetallic Compounds in Lead-Free Solder Joints: A Review. Materials.

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