90% Less Cooling Energy
Lower Server Failure Rates
90% less cooling energy
Our coolant is controlled to 40° C. It requires very little energy to maintain GreenDEF™ at 40° C (104° F) because heat naturally flows from hot (inside) to cold (outside). By comparison, air conditioners typically chill water to 7° C and then use that water to cool the air in the data center to around 23° C (74° F). Chilling water requires a much more energy-intensive process of pumping heat outside. As a result, GRC can save a significant amount of energy by not requiring water chilling.
Additionally, moving large quantities of air is much less energy efficient that moving small quantities of fluid.
Server Failure Rates
Our solution offers the potential to lower failures significantly in three ways:
- Removal of all server fans
- Low temperature gradient
- Better electrical connector reliability
Server fans are one of the largest reasons for server failures.
External to the server, data centers do not evenly cool all the servers in a rack: the temperature at the top of a rack may be 10 °C hotter than the bottom of the rack, while our servers enjoy ± 1 °C temperature variation from one end of the rack to the other.
Inside the server, local hot spots can occur due to the accumulation of dust, an excellent thermal insulator, and uneven air flow. Dust and other contaminates are removed in the GR Cooling system down to a few microns in particulate size. Due to the large heat capacity of the fluid, 1,200x higher than air by volume, temperature differences around power dense components should be significantly reduced. As an example the CPU’s are measured to be as much as 20 °C cooler than in an air cooled system with comparable load.
Our coolant enhances electrical connections because the dielectric strength is 6x that of air (12MV/meter vs. 2 MV/meter) which allows less micro-arcing. The micro-arcing causes intense localized heating, which then creates corrosion and oxidation. Micro-arcing in air is why many connections are gold plated. The use of dielectric compounds to increase connector reliability is well documented and common in other industries such as industrial automation, automotive, and the military.
Our system will cool up to 100kW in a 42U rack in its current configuration. This is equivalent to an air-cooled system near 120kW since nearly 20kW of that 120kW would be used by server fans. Our system offers orders of magnitude better convective cooling than an air-cooled system and thus can handle higher densities.
Also, full immersion of all components is unique to dielectric fluid submersion. Without full submersion, air is still the primary heat transfer medium and with it comes all of the limitations of air. For the rare CPU that is “thermally coupled” with a liquid, which entails a water-filled heat sink or equivalent, other components still require air cooling. For an independent discussion on this issue, see this article.
Over-Clocking Servers with Liquid-Submersion Cooling Technology - Results from over-clocking trials conducted using the CarnotJet™ system. We tested the ability of our system to dissipate over 200 Watts per CPU.
GRC is working on multiple white papers to be added Spring 2011, including fiber optics and general technology. For case studies, see Customer Tab.
The initial, favorable, results are in from fiber optic testing, with the detailed results available upon request. Tests were conducted with Cisco optical switches first in air, and then immersed in coolant, using UDP throughput performance tests and minimal interval ping floods. The tests showed no degradation in transfer times nor error rate.
While as noted above the coolant is controlled to 40° C, we can run our coolant up to 60° C with typical Xeon x86 processors to allow ease of heat recapture. This is because our coolant at 40° C keeps the CPUs much cooler than while in an air-cooled rack, and therefore we could raise our coolant temperature by up to 20° C while still operating in normal temperature ranges.
The limiting factor in coolant temperature is platter-style hard drives, which typically do not operate best at higher than 45° C, so users desiring heat recapture will likely use alternatives to hard drives.