Editing Computer cooling (section)

==== Data center cooling ====
Because [[data center]]s typically contain large numbers of computers and other power-dissipating devices, they risk equipment overheating; extensive [[HVAC]] systems are used to prevent this. Often a raised floor is used so the area under the floor may be used as a large [[plenum space|plenum]] for cooled air from a CRAC (Computer Room Air Conditioner) or a CRAH (Computer Room Air Handler)<ref name="auto1">{{cite web | url=https://www.cedengineering.com/userfiles/M05-020%20-%20HVAC%20Cooling%20Systems%20for%20Data%20Centers%20-%20US.pdf | title=CED Engineering }}</ref> and power cabling. A plenum made with a false ceiling can also be present.<ref name="auto1"/> Hot Aisle containment or cold aisle containment are also used in datacenters to improve cooling efficiency.<ref>{{Cite web|url=https://www.missioncriticalmagazine.com/ext/resources/MC/Home/Files/PDFs/WP-APC-Hot_vs_Cold_Aisle.pdf|title=Wayback Machine|website=www.missioncriticalmagazine.com}}</ref> Alternatively slab floors can be used which are similar to conventional floors, and overhead ducts can be used for cooling.<ref>{{cite web | url=https://www.datacenterknowledge.com/archives/2009/04/20/the-worlds-largest-raised-floor | title=The World's Largest Raised Floor? | date=20 April 2009 }}</ref><ref>{{cite web | url=https://www.datacenterknowledge.com/the-evolution-of-microsofts-data-center-designs | title=The Evolution of Microsoft's Data Center Design &#124; Data Center Knowledge &#124; News and analysis for the data center industry }}</ref>{{clear}}

Direct Contact Liquid Cooling has emerged more efficient than air cooling options, resulting in smaller footprint, lower capital requirements and lower operational costs than air cooling.  It uses warm liquid instead of air to move heat away from the hottest components.  Energy efficiency gains from liquid cooling is also driving its adoption.<ref>{{Cite web|url=https://www.datacenterdynamics.com/en/opinions/20-years-of-liquid-cooling/|title=20 years of liquid cooling|website=www.datacenterdynamics.com|date=6 April 2021 }}</ref><ref>{{Cite web|url=https://www.computerweekly.com/tip/Water-cooling-vs-air-cooling-The-rise-of-water-use-in-data-centres|title=Water cooling vs. air cooling: The rise of water use in data centres|website=ComputerWeekly.com}}</ref> Single and dual/two phase immersion/open tub cooling and single and dual phase direct-to-chip cooling<ref name="auto2">{{Cite web|url=https://www.datacenterdynamics.com/en/analysis/an-introduction-to-liquid-cooling-in-the-data-center/|title=An introduction to liquid cooling in the data center|first1=Vlad-Gabriel|last1=Anghel|first2=DCD>Academy|last2=Comment|date=28 March 2023|website=www.datacenterdynamics.com}}</ref> as well as immersion cooling confined to individual server blades<ref>{{cite web | url=https://patents.google.com/patent/US7724524B1/en | title=Hybrid immersion cooled server with integral spot and bath cooling }}</ref><ref>{{cite web | url=https://www.servethehome.com/sugon-nebula-phase-change-immersion-cooling-a-unique-platform/ | title=Sugon Nebula Phase Change Immersion Cooling a Unique Platform | date=16 November 2018 }}</ref> have also been proposed for use in data centers.<ref>{{cite web | url=https://www.networkworld.com/article/1251011/is-immersion-cooling-ready-for-mainstream.html/ | title=Is immersion cooling ready for mainstream? }}</ref><ref>{{cite web | url=https://www.anandtech.com/show/15166/two-phase-immersion-liquid-cooling-at-supercomputing-2019 | title=Two Phase Immersion Liquid Cooling at Supercomputing 2019 }}</ref> In-row cooling,<ref>https://www.vertiv.com/4a52af/globalassets/shared/liebert-xd-system-design-manual_00.pdf</ref><ref>{{Cite web|url=https://www.datacenterdynamics.com/en/news/stulz-launches-in-row-cooling-solution/|title=Stulz launches in-row cooling solution|first=Yevgeniy Sverdlik|last=Comment|date=28 February 2012|website=www.datacenterdynamics.com}}</ref><ref>{{Cite web|url=https://www.datacenterdynamics.com/en/news/schneider-launches-30kw-row-dx-cooling-unit/|title=Schneider launches 30kW in-row DX cooling unit|first=Peter Judge|last=Comment|date=3 July 2019|website=www.datacenterdynamics.com}}</ref> rack cooling,<ref>{{Cite web|url=https://www.datacenterdynamics.com/en/news/schneider-launches-rack-mounted-cooling/|title=Schneider launches rack-mounted cooling|first=Peter Judge|last=Comment|date=12 March 2020|website=www.datacenterdynamics.com}}</ref><ref name="auto3">https://agenda.infn.it/event/17962/contributions/89814/attachments/64034/77261/Paolo_Bianco_-_Liquid_Cooling_Comparison.pdf {{Bare URL PDF|date=August 2024}}</ref> rear door heat exchangers,<ref>{{Cite web|url=https://www.datacenterdynamics.com/en/news/how-the-rack-is-changing-the-cooling-game/|title=How the rack is changing the cooling game|first=John R. Phelps|last=Comment|date=10 October 2013|website=www.datacenterdynamics.com}}</ref> racktop cooling which places heat exchangers above the rack,<ref>https://www.vertiv.com/4af0e0/globalassets/shared/liebert-xdv-50-60hz-user-manual_00.pdf</ref><ref>{{cite web | url=https://www.datacenterknowledge.com/archives/2009/01/26/suns-colorado-consolidation-saves-millions | title=Sun's Colorado Consolidation Saves Millions | date=26 January 2009 }}</ref> overhead cooling above aisles<ref>https://www.vertiv.com/4af0d7/globalassets/shared/liebert-xdo-50-60hz-user-manual_00.pdf</ref><ref>{{cite journal | url=https://www.sciencedirect.com/science/article/abs/pii/S1383762121001739 | doi=10.1016/j.sysarc.2021.102253 | title=A survey on data center cooling systems: Technology, power consumption modeling and control strategy optimization | date=2021 | last1=Zhang | first1=Qingxia | last2=Meng | first2=Zihao | last3=Hong | first3=Xianwen | last4=Zhan | first4=Yuhao | last5=Liu | first5=Jia | last6=Dong | first6=Jiabao | last7=Bai | first7=Tian | last8=Niu | first8=Junyu | last9=Deen | first9=M. Jamal | journal=Journal of Systems Architecture | volume=119 | url-access=subscription }}</ref> or fan walls/thermal walls in a data center<ref>{{cite web | url=https://www.datacenterknowledge.com/archives/2016/02/03/equinix-turns-fan-walls-data-center-cooling | title=Equinix Turns to Fan Walls for Data Center Cooling | date=3 February 2016 }}</ref><ref>{{Cite web|url=https://www.datacenterdynamics.com/en/news/vertiv-launches-chilled-water-thermal-wall-for-slab-floor-data-centers/|title=Vertiv launches chilled-water thermal wall for slab floor data centers|first=Peter Judge|last=Comment|date=7 March 2023|website=www.datacenterdynamics.com}}</ref> can also be used. Direct Liquid Cooling (DLC) with cold plates for cooling chips in servers can be used due to the higher heat removal capacities of these systems.<ref name="auto2"/> These systems can either cool some or all components on a server, using rubber or copper tubing respectively.<ref>{{cite web | url=https://www.theregister.com/2022/11/19/liquid_cooling_sc22/ | title=Liquid and immersion is the new cool at Supercomputing '22 }}</ref><ref name="auto3"/><ref>{{cite web | url=https://www.datacenterknowledge.com/power-and-cooling/what-s-all-about-liquid-cooling-data-centers | title=What's All This About Liquid Cooling in Data Centers? | date=13 August 2018 }}</ref> Rear door heat exchangers were traditionally used for cooling high heat densities in data centers, but these did not see widespread adoption.<ref>{{cite web | url=https://www.datacenterknowledge.com/archives/2017/05/22/rdhx-systems-help-with-high-density-data-center-cooling | title=It Doesn't Take a Supercomputer to Justify Liquid Cooling | date=22 May 2017 }}</ref> They can be cooled with refrigerant<ref>Emerson Liebert XDR User Manual</ref> or chilled water.<ref>{{Cite web |last=Kennedy |first=Patrick |date=2021-08-02 |title=Liquid Cooling Next-Gen Servers Getting Hands-on with 3 Options |url=https://www.servethehome.com/liquid-cooling-next-gen-servers-getting-hands-on-3-options-supermicro/2/ |access-date=2024-11-22 |website=ServeTheHome |language=en-US}}</ref> Those cooled with chilled water can either be active, which have fans,<ref>USystems ColdLogik CL20 RDHx Data Sheet</ref><ref>{{cite web |url=https://www.datacenterknowledge.com/cooling/ebay-shifts-to-water-cooled-doors-to-tame-high-density-loads |title=eBay Shifts to Water-Cooled Doors to Tame High-Density Loads}}</ref> or passive, which have no fans.<ref>USystems ColdLogik CL21 RDHx Data Sheet</ref> Liquid-to-air heat exchangers (radiators) can be used to cool servers cooled with direct-to-chip liquid cooling, in order to avoid installation of facility water piping. These heat exchangers can be installed separately from racks, or as a rear door on a rack.<ref>{{Cite web |title=CoolIT Systems Launches New CDUs for AI and HPC Cooling Solutions |url=https://www.storagereview.com/news/coolit-systems-launches-new-cdus-for-ai-and-hpc-cooling-solutions?amp |access-date=2024-11-22 |website=StorageReview.com |language=en-US}}</ref><ref>{{Cite web |title=Iceotope launches liquid cooling lab in Sheffield, UK |date=9 July 2024 |url=https://www.datacenterdynamics.com/en/news/iceotope-launches-liquid-cooling-lab-in-sheffield-uk/ |access-date=2024-11-22}}</ref><ref>{{Cite web |last=Shilov |first=Anton |date=2024-10-08 |title=Microsoft Azure flaunts world's first custom Nvidia Blackwell racks — tests its own 32 GPU server rack and liquid cooling solution |url=https://www.tomshardware.com/tech-industry/artificial-intelligence/microsoft-azure-flaunts-worlds-first-custom-nvidia-blackwell-racks |access-date=2024-11-22 |website=Tom's Hardware |language=en}}</ref><ref>{{Cite web |title=QCT QoolRack Rear Door Heat Exchanger Fans |url=https://www.servethehome.com/quanta-qct-qoolrack-liquid-cooling-intel-xeon-max-overview/qct-qoolrack-rear-door-heat-exchanger-fans/ |access-date=2024-11-22 |website=ServeTheHome |language=en-US}}</ref>