The Importance of Liquid Cooling
"Energy is arguably the No. 1 challenge humanity will be facing in the 21st century. We cannot afford anymore to design computer systems based on the criterion of computational speed and performance alone," Prof. Dr. Dimos Poulikakos of ETH Zurich, head of the Laboratory of Thermodynamics in Emerging Technologies and lead investigator of the project, said in the June release. "The new target must be high-performance and low-net-power-consumption supercomputers and data centers. This means liquid cooling." Aquasar is expected to "reduce overall energy consumption by 40 percent. The system is based on long-term joint research collaboration of ETH and IBM scientists in the field of chip-level water cooling, as well as on a concept for 'water-cooled data centers with direct energy reuse' advanced by scientists at IBM's Zurich Lab."We're starting with a [IBM] Roadrunner-type machine to reach world-record performance and low emissions," Michel said. IBM in the June release said, "Each of the blades will be equipped with a microscale high-performance liquid cooler per processor, as well as input and output pipeline networks and connections, which allow each blade to be connected and disconnected easily to [and from] the entire system. ... "Water as a coolant has the ability to capture heat about 4,000 times more efficiently than air, and its heat-transporting properties are also far superior. Chip-level cooling with a water temperature of approximately 60 degrees C is sufficient to keep the chip at operating temperatures well below the maximally allowed 85 degrees C. The high input temperature of the coolant results in an even higher-grade heat as an output, which in this case will be about 65 degrees C." "Heat is a valuable commodity that we rely on and pay dearly for in our everyday lives," Michel said. "If we capture and transport the waste heat from the active components in a computer system as efficiently as possible, we can reuse it as a resource, thus saving energy and lowering carbon emissions. This project is a significant step toward energy-aware, emission-free computing and data centers." Michel said even in hot climates the excess heat can be used for desalination projects and other purposes. In the June release, IBM said, "The computational performance of Aquasar is a very important part of the research. Aquasar will be employed by the Computational Science and Engineering Lab of the Computer Science Department at ETH Zurich, for multiscale flow simulations pertaining to problems encountered at the interface of nanotechnology and fluid dynamics. Researchers from this laboratory will also optimize the efficiency with which the respective algorithms perform within the system, in collaboration with the IBM Zurich Lab. These activities will be supplemented with algorithms of other research labs participating in the project. With this supercomputer system, scientists intend to demonstrate that the ability to solve important scientific problems efficiently does not need to have an adverse effect on the energy and environmental challenges facing humanity."
"The water-cooled supercomputer will consist of two IBM BladeCenter servers in one rack and will have a peak performance of about 10 Teraflops," the June release said.