Liquid cooling

National Laboratory of the Rockies (formerly NREL) · 2026

High-Performance Computing Data Center Heat Capture and Reuse (ESIF)

In the heat-reuse module, support on-site end uses (low-temperature terminals, snow melt).

National Laboratory of the Rockies (formerly NREL) · 2026

High-Performance Computing Data Center Warm-Water Liquid Cooling (ESIF)

Use as a reference case for warm-water DLC presets (supply about 24 C, return about 38 C).

• Page last updated February 17, 2026.

Open Compute Project Foundation · 2025

High-Performance Two-Phase Cooling under Different Cold Plate Orientations (OCP EMEA Summit 2025, Future Technologies Symposium)

In CDU catalogue entries, distinguish single-phase and two-phase (refrigerant type, saturation temperature, facility-water supply temperature).

• Vendor roadmaps point to about 600 kW racks with vertically mounted servers around 2027.

Danfoss · 2024

How Danfoss Hansen Universal Quick Disconnect coupling (UQD) can meet the specific needs of thermal management applications

In the liquid-cooling catalogue store coupling size, OCP compliance, maximum working pressure, flow coefficient/pressure drop, disconnect-under-pressure limit and wetted materials.

• Sizes -02, -04, -06, -08 with ORB, hose-barb and BSPP ends.

Consulting-Specifying Engineer · 2021

How to design data centers: HVAC systems (roundtable)

Offer integrated-free-cooling chillers as a catalogue option with the free-cooling changeover ambient field.

• NREL ESIF: water-cooled racks with thermosyphon plus towers achieved PUE 1.04 and halved water use.

Consulting-Specifying Engineer · 2025

How to design piping systems for data centers that require liquid cooling

Liquid-loop design rules: check pipe velocity <= 2.1 m/s above 3 in. NPS and TCS supply >= dewpoint + 2 C, and flag incompatible wetted materials.

• TCS supply must be held at least 2 C above room dewpoint to avoid condensation.

Leibniz Supercomputing Centre · 2025

HPC and AI in Supercomputing Centres: Green Today, Greener Tomorrow (SCA25 Workshop on Energy Efficiency, LRZ)

Let liquid-cooled design templates allow facility supply temperatures up to 45 C with dry-cooler-only heat rejection, and show the resulting PUE.

• Systems span from SuperMUC (2012) to SuperMUC-NG Phase 2.

Huawei Digital Power · 2025

Huawei AI Data Center Reference Design

Import RD 01-21 as parametric AI-hall templates (rack kW, racks per module, module kW, redundancy of fan walls/TMUs/towers, generator and transformer counts) and as golden test cases for capacity math.

• Power distribution supports 2N, DR and BR architectures.

Cundall (for Iceotope Technologies) · 2021

Iceotope Engineering Review - Desktop Study Report: Liquid and Air-Cooling Compared

Catalogue liquid-cooled IT and CDUs with ASHRAE W-class and supply temperature fields, and use these to decide whether compressor cooling can be omitted for the site climate.

• Per kW IT versus air baseline: water use down up to 96%, power about 40% lower, CO2 about 39.5% lower.

Open Compute Project Foundation · 2025

Immersion Server Demonstrated Reliability at Datacenter Scale Deployment (OCP EMEA Summit 2025)

Give immersion tank and server catalogue items a field-reliability reference (AFR), and use component-level AFRs in the reliability module rather than assuming immersion degrades availability.

• Fleet uptime above 99.999%: about 443 million power-on hours with 1,112 h total downtime.

IEEE · 2012

Impact of Operating Conditions on a Chiller-less Data Center Test Facility with Liquid Cooled Servers (ITherm 2012)

In liquid-cooling energy calculations, account for glycol concentration (higher pumping power, lower heat transfer) and flow-rate set points, not just supply temperature.

• Typical baseline facilities spend about 50% of IT energy on cooling, mostly in chillers and CRAHs.

Uptime Institute Journal · 2026

IT-agnostic DLC systems: key considerations (Daniel Bizo)

Catalogue DLC loops with coolant type (PG25/DI), filtration rating (default 25 micron) and wetted materials.

• Industry-standard filtration for water DLC networks is 25 microns, usually full-flow at the CDU; side-stream filtration helps in multi-MW networks.

STULZ · 2024

Keeping Emmy Cool - White Paper (STULZ Modular, University of Gottingen hybrid liquid/air cooled HPC data centre)

Model the per-rack heat split (liquid %/air %); it drives both CDU and CRAH sizing.

• 11 racks installed at 96 kW, space for 14.

STULZ · 2025

Liquid Cooling - Exponentially increasing power density: At what pace should Liquid Cooling be implemented?

Define rack templates per GPU generation with a default kW and liquid/air split, for example 85/15 at 130 kW and 100/0 at 600 kW.

• 600 kW racks require 100 % liquid cooling.

STULZ · 2025

Liquid Cooling - When performance meets sustainability: the data center cooling challenge

In the CDU selection tool let users trade approach temperature against heat-exchanger area and TCS delta-T, with Cases 1-3 as validation fixtures.

• Case 2: same duty with APT 2 K needs 143.6 m2 (double).

Energy Efficient HPC Working Group · 2013

Liquid Cooling Commissioning: Lessons Learned @LRZ (EE HPC WG session, SC13)

In commissioning checklists the tool generates for liquid-cooled plants, include verification that instrumentation matches manufacturer specifications.

• LRZ runs four loops: warm water 30/36 C, cold water 14/20 C, very cold water 4/10 C, plus a glycol/heating loop.

ASHRAE · 2013

Liquid Cooling Guidelines for Datacom Equipment Centers, 2nd ed. (ASHRAE Datacom Series Book 4)

In the DLC data model, keep facility water (FWS) and technology cooling system (TCS) loops separate, with a CDU as the interface.

• Authored by ASHRAE TC 9.9.

WSP · 2026

Liquid cooling in African data centres: A turning point in efficiency, resilience and future-ready design

For TCS loops, add coolant fields (demineralised water, PG percentage).

Data Center Knowledge · 2026

Liquid Cooling Retrofits: Hard, but Sometimes Worth It (Christopher Tozzi)

Add a retrofit check comparing liquid-cooled rack weight (default up to about 3,000 lb / 1,360 kg) with the raised-floor rating.

• Fully loaded AI racks with liquid cooling can exceed 3,000 lb, which raised floors may not support without reinforcement.

STULZ · 2026

Liquid Cooling Whitepaper - End-to-End Cooling: The Key to Resilient AI Data Centers

In the liquid-cooling module size TCS flow at about 1.5 L/min/kW by default and store CDU approach temperature and external static pressure.

• Rack heat densities from about 125 kW today to beyond 500 kW.