Peregrine Cooling Systems - The Nodes
The High Performance Computing environment at NREL represents a departure from traditional air-cooled datacenter practices in an effort to maximize efficiency even with high power-density environments, such as the Peregrine HPC cluster.
Each Peregrine tray contains two nodes which utilize heat pipes to transfer heat energy from the CPU and memory--which generate the majority of the heat--to the edge of the case. It is then transferred through thermal bus bars (specially designed interconnects) and into the water wall, where the cooling water circulates. We’ll have more on the thermal bus bar and water wall assembly in part 2 of this series. By pulling the heat out of the tray this eliminates the need to introduce cooling water into the tray with flexible tubing and interconnects, which can make service easier.
Air still flows through the trays inside the sealed racks to cool the other components but even that air is cooled and the heat captured by an air-to-water heat exchanger within the racks.
There are a number of advantages we gain by cooling with water—specifically warm water up to 80°F/27°C. Water is able to absorb and remove much more heat energy than air per unit of volume. This allows us to still provide adequate cooling while using less energy running pumps than fans would require. It also affords the ability to use more economical cooling systems, such as evaporative cooling. Finally, the waste heat we capture is reused for other needs, like heating our building.
In the next segment we’ll take a closer look at the rack-level cooling systems for Peregrine.