Back in the 50s and early 60s the Thermador was popular it mounted on the passenger side window
http://www.ebay.com/itm/Vintage-Thermador-car-swamp-evaporative-cooler-restored-/110906209732?pt=LH_DefaultDomain_0&hash=item19d28675c4#ht_500wt_950 I don't see any advantage of trying to make a heat pump type heat exchanger you just can not get enough air circulation with the muffin fan
I used to live in an area with 50% average relative, my swamp cooler did just fine as long as I kept an old Mathes Box fan in an opposite window facing out to. other wise when the humidity was around 80% there was hardly any cooling effect at all.
Never use a swamp cooler in a totally closed house the humid air is traped and can cause mold Sheetrock is a mold magnet. in non circulation areas humidity can build to 100% any microscopic airborne mold will be sucked in and begin to grow. Any time humidity was above 80% relative I kept all closets & cabinet doors open
Misting should only be used outside like on a shaded patio. A very fine almost fog like mist with a fan blowing from behind offers a fair amount of cooling if the Humidity is below 30% .0 to 10% desert conditions can make it feel as much as 30 degrees F cooler
Most industrial self contained shop coolers used Aspen pads sometimes called excelsior but other medias called excelsior were shredded cyprus, strawor even palm leaves depending on where the coolers were made
Cellulose fibers started being used somewhere around the 70s But it has improved and been made into rigid open pore pads and blocks" CELdek®" this is now the choice of industrial shop coolers or a similar brand
For a home built unit it is just about always going to be cheaper to buy a ready made swamp cooler
But an evaporative cooling tower with heat ex changers circulating closed loop chilled water with an air handler can be a viable alt. to adding more moisture in the house air