Event Recap
RECAP | ROUNDTABLE | Direct Liquid Cooling Applications
Participants in a March 10th Inside Track roundtable shared quite a bit of first-hand experience with direct liquid cooling, especially liquid immersion systems, despite the technology’s low adoption rate. During the session, three participants shared the outcomes of technology tests conducted, in part, to accommodate higher-density workloads anticipated in their facilities. Ryan Orr, Uptime Institute’s training program director, joined the discussion. He discussed the strengths and weaknesses of various direct liquid cooling technologies and compared and contrasted them with top of rack and rear-door heat exchangers, as well as traditional air-cooling systems.
Kevin Heslin, chief editor, Uptime Institute, also joined the discussion. He helped the participants achieve a consensus that most enterprises had not yet achieved power densities that would require direct liquid cooling. As part of this discussion, Orr noted that he had seen raised floor applications capable of cooling loads as high as 25 kilowatts per rack, without heat exchangers or direct liquid cooling. Still, he noted, some organizations might consider direct liquid cooling to improve efficiency. And one roundtable member suggested that the high temperatures of dielectric fluids found in many systems made them potential sources for heat recovery applications.
The results of direct liquid cooling system tests on immersion cooling systems were mixed. For example, a two-phase system
• Required protective gear because the liquid temperatures reached 60 C
• Damaged fiberoptic connectors
• Contained mineral oils that are difficult to clean and posed Environmental Health and Safety concerns when spilled
Other roundtable participants found that single-phase immersion systems could also damage ethernet connectors.
Further discussion of immersion systems led to the topic of microcavitation, which causes small waves in the dielectric fluid that can delaminate server boards. One of the participants added that the bubbling of the fluid that causes the waves increases the efficiency and cooling capacity of the immersion system.
During the session wrap up, Orr pointed out two additional concerns. He said that no Tier III or Tier IV facility had depended on direct liquid cooling to address its heat loads to date, but that possibility is being.
Outside of Tier compliance, direct liquid cooling still lacks redundant features at some point (be it removal of the cooling liquid or other non-redundant internal equipment). This problem will require an IT-based solution for redundancy. For example, adopting the concept of digital resiliency and having multiple pieces of hardware to support the computing load requirement. Just as important, he said, was the disruption to the supply chain that would be caused by the wide-scale adoption of direct liquid cooling technologies. Use of these servers would disrupt well-established procurement and testing procedures in place for current-generation servers.
Kevin Heslin, chief editor, Uptime Institute, also joined the discussion. He helped the participants achieve a consensus that most enterprises had not yet achieved power densities that would require direct liquid cooling. As part of this discussion, Orr noted that he had seen raised floor applications capable of cooling loads as high as 25 kilowatts per rack, without heat exchangers or direct liquid cooling. Still, he noted, some organizations might consider direct liquid cooling to improve efficiency. And one roundtable member suggested that the high temperatures of dielectric fluids found in many systems made them potential sources for heat recovery applications.
The results of direct liquid cooling system tests on immersion cooling systems were mixed. For example, a two-phase system
• Required protective gear because the liquid temperatures reached 60 C
• Damaged fiberoptic connectors
• Contained mineral oils that are difficult to clean and posed Environmental Health and Safety concerns when spilled
Other roundtable participants found that single-phase immersion systems could also damage ethernet connectors.
Further discussion of immersion systems led to the topic of microcavitation, which causes small waves in the dielectric fluid that can delaminate server boards. One of the participants added that the bubbling of the fluid that causes the waves increases the efficiency and cooling capacity of the immersion system.
During the session wrap up, Orr pointed out two additional concerns. He said that no Tier III or Tier IV facility had depended on direct liquid cooling to address its heat loads to date, but that possibility is being.
Outside of Tier compliance, direct liquid cooling still lacks redundant features at some point (be it removal of the cooling liquid or other non-redundant internal equipment). This problem will require an IT-based solution for redundancy. For example, adopting the concept of digital resiliency and having multiple pieces of hardware to support the computing load requirement. Just as important, he said, was the disruption to the supply chain that would be caused by the wide-scale adoption of direct liquid cooling technologies. Use of these servers would disrupt well-established procurement and testing procedures in place for current-generation servers.
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