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Keeping a Data Center Cool on the Cheap
jedimaud writes "You've heard of bubble wrap, and the boy in the bubble -- now, here's a datacenter in a bubble. I work for a government agency that, like most, is trying to cut back some costs, and one of those costs is a REAL datacenter. So, we decided to wrap the whole thing in plastic (including two 1.5 ton ACs). The room hovers about 83 degrees, however, the racks in the bubble (ok, more like a termite tent) stay about 10 degree cooler. Here's some pics to check it out."
"(including two 1.5 ton ACs)"
"Ton" here refers to a "ton of cooling," a measure of power. It was originally intended to mean "the power required to melt one ton of ice in 24 hours." Since that varies based on a bunch of conditions, it was pegged at 12,000 Btu/h.
When they changed the definition of "calorie" to mean 4.1868 J, converting Celsius to Fahrenheit and grams to pounds gives us a conversion factor of 1 ton of cooling being exactly 3 516.852 842 066 7 W.
In other words, each a/c unit is about 5.25 kW of cooling each, or 10.5 kW total.
Oh, and 83 degrees Fahrenheit is about 301 kelvin and a ten-degree Fahrenheit difference is a difference of 6 kelvin.
(According to my old HVAC prof, there's been little to no progress in "metricizing" the industry in the US. Having used both systems in his course, I'd say I prefer US units, if only because the unit descriptions on things like insulative properties make more sense when the units for thickness and area don't naturally cancel each other out.)
(And it could be worse. Most home a/c units are labelled on the box as putting out x number of Btu, suggesting they're disposable.)
(Well, they probably are...)
First off, a "real" data center needs a little more than 1.5 Tons of cooling; that will barely cool a single rack in a real data center.
Insulation is always a nice idea, be the fact of the matter is that to reject the heat from the space you need to provide a means of heat trasnfer. Generally, that requires a temperature differential between your heat source and the outside. If it is cooler outside than in the space, not much is required. If it is warmer, you will have to take advantage of thermodynamics and use a compressorized cycle. This can be more or less efficient, depending on the difference in inside and outside temperatures.
(A typical data center operates with a 95-110F outside design temperature, and attempts to deliver 48F chilled water to the CRAC units (Computer Room Air Conditioning). This forces about 50% of the energy consumed by the computers to be used (again) to cool the equipment.)
Call an engineer when everything melts down...
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"Plans are for fools! Oglethorpe, the plutonian (Aqua Teen Hunger Force)
Excuse me, do you run a datacenter for a living?
When you are running a mission critical datacenter (this is usually all of them, if we are talking about real datacenters here, not the closet of your 5000 square foot PC repair shop where you keep your web server), you have supplies to get you through any length of power outages. This usually includes supplies of diesel fuel and a contract with a fuel supplier to bring more diesel on site for the duration of the outage.
Do you have any clue how major datacenters in metropolitian USA are run? You don't depend on the reliability of the grid to determine how to budget power systems for your datacenter.
-AC with a clue
No offense, but maybe you missed the point?
The article was entitled "Keeping a Data Center Cool _on the Cheap_" (emphasis added)
The suggestion being that they were able to significantly cut back on the size and power consumption of the cooling plant by using plastic wrap.