May 08, 2014

How to choose between hot and cold water cooling for data centers?

I’ve read that hot water cooling for data centers is superior to cold water cooling. This seems completely counterintuitive. How can hot water cooling be superior to cold water cooling?

Here's an interesting example.

Department of Energy Using Warm Water to Cool New Data Center

"The classic data center has lots of cold air that is approximately 60 degrees supplied to the front of the racks, in an effort to help keep your chips from getting hotter than 150 degrees," Hammond said. "Then you get 80 degree hot air out of the back of the racks and you try to eject that heat and declare victory."

Hammond explained that in contrast, the NREL approach will supply water that is approximately 75 degrees and then after running through the servers, will return water that is 95 degrees. That return water will then be the primary heating source for the building."

It does seem counterintuitive, but it has been proven to work. The term “hot water” really means “hotter water” because it isn’t run through chillers (or at least the chillers run less often). There isn’t a single design that all hot water cooling systems use at this point, but rather a few different concepts. There have been a number of projects that make use of the heated water to heat buildings, thus providing a way to cool the water and gain “free” heat, which is both green and cost effective. Here is an article that goes into it a little more:  http://www.datacenterknowledge.com/archives/2012/06/25/hot-water-cooling...  

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