How Do You Cool Your Data Center / Server Room?

Solar water heating tubes on the roof--that's an evacuated glass tube with a heat pipe running up hill to a heat exchanger embedded into a hot water loop.

Water-ammonia-hydrogen absorption refrigerator. The hot water loop loops down, runs into a water block that heats up the base reservoir of ammonia-water. This is in a small attic room with a weather sealed door and two fans (intake and exhaust). If the absorption refrigerator experiences a breach, the ammonia is vented to the atmosphere (it's poisonous, but harmless--ammonia is produced as part of the biological process, and is consumed by yeast and other microbes). Doesn't normally breach--the unit is sealed and needs zero maintenance ever.

The initial cooling loop ventilates heat into the room. After that, the cooled expanded ammonia travels through a condenser where it condenses into liquid ammonia at ridiculously low temperatures. The condenser itself is inside an oil-filled block which itself extends cooling fins into a run of duct work. The actual compartment with the condenser is separate, so if the condenser and housing crack it just splatters oil and evaporates ammonia into the outside atmosphere rather than into building duct work. Condensed ammonia goes back into the base unit where it's boiled again to recirculate.

The fans are run by compressed air. The air is compressed by sterling engine. Operating temperature is lower than the breakdown temperature of teflon seals, and so alpha sterling engine layout with hot teflon seals is used. No fluid lubrication required, so absolutely no maintenance. Compressed air also runs pumps that drive the hot loop and a cold loop that exchanges the sterling engine's heat with a ground tapped sink. A backup compressor is physically in another room and driven by electricity in case of failure of sterling engine. This is to avoid sparks in the event of a critical breach of the absorption refrigerator, instead allowing volatile hydrogen and ammonia to vent to atmosphere.

Hot loop is supplemented by a box of slate and oil to store excess heat collected during daylight hours for use at night. Hot loop is backed up by a separate, exchanger coupled loop that passes hot working fluid through a hot water exchanger coupled to a boiler to provide heat from gas via the building's existing hot water system. In the winter, system is bled during the day to provide building heat, and waste heat from heating turbine is used at night to supplement system if working temperature drops critically from lack of stored heat energy.

Impressed?

It's very Rube-like because it's got so many caveats related to "this thing should never break open BUT if it does it will silently kill everyone in the building, unless it explodes first."

Ammonia cloud flooding the lower floors (say we put it in the basement) will poison everyone in a large area to death. This operates at above atmospheric pressure and with a hell of a lot of ammonia.

The thing uses hydrogen to more efficiently condense ammonia. Hydrogen released into atmosphere is explosive and will cause fires.

To solve these, you physically isolate the damn thing and you isolate it from fire and electricity. You also add a ton of ventilation (suck air in one window, out the other). On top of that, there's provisions for running when the sun isn't shining or when the working temperature just isn't hot enough.

At the core, it's a machine with no moving parts that allows you to apply fire to one side and watch icicles immediately start forming on the other. So instead of fire, we're using the sun.