Helping Microsoft keep their cool

Advanced Technologies

Helping Microsoft keep their cool

Our American office was approached by Microsoft to help solve a key challenge in their quest to develop a more efficient datacenter cooling system, using two-phase immersion cooling that would help the company towards the realisation of their emissions reduction goals.

They tasked us with designing a passive method of removing air from the system that may be introduced during a maintenance procedure, as the air would have a detrimental effect on the overall cooling performance.

By designing and constructing our own test rig, on which we could conduct a range of in-depth trials and analyses, and developing cutting edge CFD models for rapid design evaluation, we were able to deliver a passive air purging process as requested and deliver a modelling system that can be used for future system developments.

While conventional cooling dominates datacenters today, immersing servers in a non-conductive, low boiling point fluids such as 3M™ Fluorinert™ delivers far greater cooling performance, more consistent cooling distribution across server components, and it gives greater protection against hot spots that can significantly shorten the life of server components.

With a boiling point of just 50°C, Fluorinert™ readily transitions from a liquid to a gas, before being cooled by a condenser where it returns to liquid form and repeats the cycle. If air is introduced into the system, perhaps when the server enclosure is opened for maintenance, the performance of the condenser is reduced, with a corresponding adverse effect on the system’s overall efficiency.

To verify the principles at work, we designed and constructed a test rig to act as a scale model that incorporated all major components, with a boiler to simulate the heat load produced by the server. The rig included a species separator that takes advantage of the difference in density between the Fluorinert™ vapor and the air to be removed from the system.

Design work was then carried out using advanced computational fluid dynamics (CFD) models, running transient simulations of the gas and liquid flows. We used Schlieren photography on the test rig to visualise the airflow through the species separator, validate the CFD results and refine the design to optimise the removal of the unwanted air.

Armed with the findings of our research, Microsoft were able to continue their new datacenter cooling development, with new design and validated modelling techniques to ensure that successful new designs are delivered, rapidly and reliably.

 


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Click the icon to download the whitepaper “A novel concept for air removal in two phase immersion cooling systems”.