Slashdot Mirror
"Heat Wheel" Could Lower Data Center Power Bills
miller60 writes "An air conditioning technology called the 'heat wheel' is getting a test drive in data centers, and early adopters cite impressive reductions in their power bills. The heat wheel — also known as a rotary heat exchanger or Kyoto Cooling — is a refinement of cooling systems using outside air. Rather than introducing exterior air directly into the server room (the air economization we discussed recently), the heat wheel briefly mixes the outside air and exhaust air to create an air-to-air heat exchanger. A data center in the Netherlands using this approach only has to use chillers 11 days a year." The article points out that the heat wheel is not new, but it hasn't been applied to data centers until recently.
There is a reason that telephone exchanges are run on -48VDC, and it's not some fscked up reason like "oh, that's how they ran the first switches in England, and we never got around to changing."
Ah, I know that one, or at least half of it. The reason for the negative voltage is electrolysis. A positive voltage would result in a migration of metal from wires exposed to the environment (telephone poles) to earth. Negative voltage makes the infrastructure last longer.
As for the magnitude being 48 Volts (actual spec. usually 36-72 volts) it most likely has to do with the maximum voltage drop between the central office and the terminal (phone).
He may well have read TFA. The article and your post only mention 'Airside Economizing' which mixes the two air flows. Heat exchangers don't necessarily do that, and have been around for a very long time. Even the old VW bug used a system that didn't mix. All this system does different is use a wheel, adding a moving part to a very common method of stripping waste heat from plant exhaust.
The article specifically omits comparing it to other heat exchanger systems. They give an example data center, but don't tell us what the data center did before.
Most telling is the quote: "Heat wheels have been used for many years in industrial air conditioning, but never in data centers." Other than asking "really?" and "why not?", since data centers are industrial use, the question is why aren't they comparing like with like here? There were plenty of things like this when I was dealing with 'super-insulated' building construction in the 80s.
This article is really just the manufacturer's PR release regurgitated, and is properly tagged 'slashvertisement' here. Data center managers should definitely know about heat exchanger technology, but get a better source.