Air-Assisted Direct Liquid Cooling: An Overlooked Option

Overview

This document is a five-page report from Uptime Institute Intelligence, published as UII Update 233 in the first quarter of 2024 and written by J. Williams-George and D. Bizo. Its subject is direct liquid cooling (DLC) designs that pass heat to room air rather than to a facility water connection. The report sits behind a registration form or subscription; only the information on the public landing page has been used here.

The starting point is that the need for a facility water connection is a key barrier to DLC in air-cooled facilities. Air-assisted DLC removes that requirement because it rejects heat to air instead of water. Liquid-cooled servers can therefore be placed more easily in existing halls that have no water infrastructure. There is a price: according to the landing page, the approach trades some performance for ease of deployment and operation.

The public page gives no numbers on how large that performance penalty is. The document is therefore a short assessment pointing to an overlooked option, not a full design guide. The practical takeaway for engineers is that moving an air-cooled site to liquid cooling does not always require a new water loop, but the rejected heat still ends up in the room air and therefore loads the air-conditioning system.

Key points

1. Air-assisted DLC removes heat to air instead of a facility water connection.
2. The facility water connection requirement is a key barrier to DLC in air-cooled facilities.
3. Published as UII Update 233 in Q1 2024.
4. Five-page report by J. Williams-George and D. Bizo.
5. The approach trades some performance for ease of deployment and operation.
6. The full report is behind registration or subscription.

Using it in design

• Offer a 'liquid-to-air CDU / sidecar' as a DLC option.
• Add the heat rejected to room air to the CRAH sizing.
• For existing halls without water infrastructure, compare facility-water DLC with air-assisted DLC on cost and performance.

Who should read it

Designers and operations engineers considering adding liquid cooling to existing air-cooled halls.

Publication details

Authors

J. Williams-George; D. Bizo

Publisher

Uptime Institute Intelligence

Year

2024

Document number

UII Update 233

Document language

English

Source type

Industry body

Access

Citation only

Licence

Copyright retained; citation only — the publisher’s terms apply to the original document

Citation