Liquid Cooling Teams

The Energy Efficient HPC Working Group (EE HPC WG) has had several Liquid Cooling Teams over the years. The focus is on encouraging highly efficient liquid cooling. This promotes the use of high temperature fluids delivered to the inlet of IT equipment in order to eliminate or dramatically reduce the use of compressor cooling (chillers). It provides operational guidance on liquid cooling for HPC sites, architecture and engineering firms and liquid cooling solution vendors. Finally, it seeks industry endorsement of open standards to promote adoption of liquid cooling.

The most recent work has been to support industry initiatives for open multi-vendor solutions of liquid cooled computer racks where the liquid cooling infrastructure can be reused through multiple refreshes of liquid cooled computer hardware. Multiple industry organizations are involved in open liquid cooling standards, including American Society of Heating, Refrigerating and Air-conditioning Engineers (ASHRAE) and the Open Compute Project (OCP). This particular focus has been on making recommendations for transfer fluids in the secondary or closed loop technology cooling system.

DOCUMENT: Transfer Fluid Water Treatment for Closed Loop Hydronic Systems

https://drive.google.com/file/d/1LS3Kvj0U_u4af1oLVbETyOG0FU_NnsW4/view?usp=sharing

Prior to that, we built upon the lessons learned from early adopters of large scale liquid cooled systems to make recommendations for commissioning liquid-cooled systems. Techniques employed include: a) pressure testing for leaks, b) flow tests to ensure proper valve operation, flow rates, and controls sequencing, and c) load simulation to ensure demand is met. Proper operation of liquid cooling systems is critical for liquid-cooled equipment because safety margins are very small and cooling fluid flow cannot be disrupted without causing a system outage and/or damage to computing equipment.

DOCUMENT: Systematic Approach For Universal Commissioning Plan For Liquid-Cooled Systems

https://eehpcwg.llnl.gov/assets/lcc1_liquid_cooling_commissioning.pdf

The initial work was to work with ASHRAE on liquid cooling design guidelines. These guidelines specify liquid cooling temperature ranges for liquids cooled by cooling towers or dry coolers. This establishes a common design goal between supercomputer manufacturers and the supercomputer facilities for the definition of liquid cooling temperatures supplied to the supercomputer at the building interface point.

DOCUMENT: Hot" for Warm Water Cooling

https://datacenters.lbl.gov/sites/default/files/Hot%20for%20Warm%20Water%20Cooling.pdf

It is intended that these documents encourage dialogue in the entire community about liquid cooling for HPC. Cooling is very site specific and requirements might vary according to many things, including the size of the HPC datacenter and HPC system being cooled. Also, each HPC center has its own unique mission, and priorities may differ greatly between centers.