My understanding is that evaporative cooling can pose a risk to electronics, as the air might become saturated with moisture. I am in search of some expert advice on this subject.
1) Is this a feasible option?
2) How risky is it?
3) Can the risks be addressed?
4) If not, what is a better option?
I work for a company that runs a few different datacenters with cheap power in WA state. We do actually use evaporative coolers in one, pretty neat system. So let me do my best here:
1) Yes evaporative coolers are an option for datacenters but it depends on the type. The cooler you linked to would be a "Direct evaporative cooling" type which basically is just like a regular swamp cooler (see: http://en.wikipedia.org/w/index.php?title=Evaporative_cooler then the "Direct evaporative cooling" title) and is not suited for datacenter use as the temperature drop is very low and a large amount of moisture is added to the air. Eventually the air can become saturated with humidity too high for the electronics to survive and then you risk frying electronics simply due to condensation concerns...
2) Well for a quick test get a regular swamp cooler in a closet, put a computer near the air output and see how long it lasts... There is obviously a much more technical answer but even then it just depends on a lot of factors. Most swamp coolers pull in outside air and rely on air entering/leaving the space to prevent the buildup of moisture. Remember these "evaporative coolers" feel a lot colder to us humans than it actually drops the temp due to the evaporation aspect. Again if you were to just recirculate the same air over and over eventually it would just be hot muggy air, and you would get condensation and start frying stuff. Really evaporative cooling could be described as "add water to the air to make it feel cooler". Again - this only goes so far and only works so much.
3) Yes by changing the design to "Indirect evaporative cooling" (refer to the wiki link) where you use a heat exchanger this eliminates a large amount of the humidity. But even this has its limitations and thus the options used for a datacenter are generally a standard AC/evaporative combination which leads us to:
4) What datacenters use: http://www.trane.com/datacenter/pdfs/TR_EvaporativeCooling_web.pdf (problem: $$$$$)
Really all the core data is written right on the wiki:
DISADVANTAGES:
- The air supplied by the evaporative cooler is typically 80–90% relative humidity;
- High humidity in air accelerates corrosion, particularly in the presence of dust. This can considerably shorten the life of electronic and other equipment.
- High humidity in air may cause condensation of water. This can be a problem for some situations (e.g., electrical equipment, computers, paper, books, old wood).
So how much humidity do you want? Not this much:
"a problem in the facility's building-management system led to high temperature and low humidity air from the hot aisles being endlessly recirculated though a water-based evaporative cooling system that sought to cool the air down – which meant that when the air came back into the cold aisle for the servers it was so wet it condensed."
Long story short:
"Some servers broke entirely because they had front-facing power supplies and these shorted out. For a few minutes, Parikh says, you could stand in Facebook's data center and hear the pop and fizzle of Facebook's ultra-lean servers obeying the ultra-uncompromising laws of physics."
http://www.theregister.co.uk/2013/06/08/facebook_cloud_versus_cloud/
The problem is any home-grown evaporative cooler solution is going to have that exact same problem. Miner heats air > Evap cooler adds water (cools a bit) > miner heats air more > evap cooler adds more water (cools even less) > miner heats air > .... rinse repeat until you have a jungle! ... then POP/FIZZLE...
Why not just leave a window open?