It's an evaporative cooling "system" perhaps "swamp" because it's wet, or because it's simple/primitive?

A family member had one to cool his store, and another family member had a big one for a movie theater.

From: http://en.wikipedia.org/wiki/Evaporative_cooler
"small-scale evaporative coolers are called swamp coolers by some users due to the humid air conditions produced."

Grigg