Google patent promises more efficient data centres by positioning heat exchangers right behind the servers
The search giant has yet to explain the reasoning behind the patent, but from the document itself, it seems the company is publishing details of how to cool a datacentre using water cooling in heat exchangers between the servers, i.e. inside what is normally known as the “hot aisle”. The patent is issued to a Google property called Exaflop, which has held other patents for Google before.
A big change for data centres?
Keeping IT equipment in data centres cool is an important task, and there is a vast array of efforts going on in the industry to make this more efficient by reducing the amount of energy required to stop the servers overheating.
Computers in a data centre use a lot of electrical energy, and convert it all into heat, the patent explains. Because that heat has to be removed, it says “operating a data center is like an electrical double whammy–you have to pay once to use the electricity, and you have to pay again to remove the effects of the use of the electricity (which itself requires more electricity).”
Organisations like the Green Grid have been agitating for data centres to reduce their energy use by applying cooling more efficiently, and measuring it through the PUE (power usage effectiveness) measure. Meanwhile, big data centre owners and operators like Amazon, Google, Facebook and Apple have been doing their own work, using their huge spending power to get more efficiency from their suppliers.
Servers are normally installed in tall racks, arranged in lines in the data centre. The patent describes a heat exchanger unit to be placed behind the racks of servers.
Hot air emerging form the back of the servers is blown upwards through heat exchangers, and emerges form the top of the unit to be recirculated through the server room.Facebook has started the Open Compute specification, which publishes designs for more efficient servers, while Google has been operating a charm offensive, showing how green its data centres mostly through a picture campaign. This patent looks like a more open approach.
The heat exchanger units are connected to a supply of cool water provided by a cooling system outside the data centre, which could be a modern evaporative cooling system, or an old fashioned mechanical chiller.
Is this exciting?
The approach looks intriguing, but raises some questions. Most data centre cooling schemes rely on rigid separation of a cool aisle from a hot aisle, where hot air emerges from the back of the servers, Not many systems actually place cooling in the hot aisle, with most of them cooling the air before it goes into the racks.
It’s not clear, either, whether this is the system already in use within Google’s data centres (pictured), or how Google intends to use the patent: whether it will enforce it for money, or offer the design for others to use to make their data centres more efficient, too.
Data centre experts say it fits with existing concepts for data centre cooling, but simplifies the implementtion: “Conceptually it’s not that dissimilar to a rack exit door heat exchanger with fans, from people like OptiCool and IBM, or contained hot aisle ducted to AHUs [air handling units] with cooling coils in them,” said Zahl Limbuwala of Romonet.
By putting the units directly between the server racks, Google has done away with the ducting, and made the rows of server racks “room neutral”, because the air coming out of the top of the unit is close to the ambient room temperature, Limbuwala observed: “It makes sense as a low cost high density solution – and Google are all about lowest cost to get the job done.”
Google has not yet answered our request for information, and the other cooling companies we contacted weren’t willing to commit themselves on the new patent. Many found the images hard to view – the US Patent Office displays them in Apple Quicktime format, which is immensely hard to view without using the Safari browser – our gallery is a set of screen grabs, which may help to explain the concept.
Finally, many thanks to David O’Hara, of the Green (Low Carbon) Data Center Blog for spotting this.
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