Evaporative cooler questions

[Atokatim]

I have taken a little interest in building an evaporative cooler but I am not sure how effective it will be in my area.  The humidity plays a huge factor in whether I will build one or not.  With basic testing, putting a wet rag over a fan, the air cooled off almost immediately.  This shows that I may be able to use an evaporative cooler even with the humidity higher in my area.  The humidity is on average around 20% to a max of 40%.  I have tried the wet rag test on a day with 40% humidity and it still got quite cold.

What I have questions about is the material to use for the cooling pads, and if misting is a good idea.  I have a few misting nozzles that I am sure I can get to mist using a fuel pump from a vehicle.  My idea is to take some sort of cooling pad and place it over a heater core or something similar.  Then, blow air through the heater core fins and mist the cooling pads at the same time.  The heater core will be connected to another heater core and both fully sealed with water or possibly anti-freeze in them.  I have a very small 12 volt pump on it's way to my house to help circulate the anti-freeze.  The idea is to have the cooling pads, that are being misted, cool off the heater core which acts as a heat exchanger.  The moist air will be exhausted back out into the atmosphere to help keep rust from happening in the area this unit will be cooling.  Then the second heater core will be mounted in the back window of my truck with a 12 volt 6" computer fan mounted to it.  Since I don't have air conditioning in my truck, I figure I would try to use this setup to help me cool off while stuck in traffic every day in 95+ degree temps.

Is this a feasible idea?  Are there any improvements that I could do to it?  Any input is appreciated!

[Frank S]

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

[Atokatim]

So misting the cooling pads instead of running water over them will not make a difference?  The reason I want to use a heat exchanger type system is to prevent water vapor from getting into the truck when I have it parked outside on the weekends or when it is out in the parking lot at work.  The natural heat would make the water evaporate and the only direction for it to go would be inside the truck.  If I vented it back out to the atmosphere, the moisture would stay out of the truck.  I do plan on having the unit covered and out of the sun as much as possible, but stopping evaporation in this kind of heat is pretty difficult.  Anything that I can do to help cool the inside of my truck besides just a fan would be great!  I usually get home from the hour drive from work with my back soaked with sweat.

[RP]

Look up "wet-bulb depression". 

This is the actual temperature difference of a wet surface based on the humidity.  It's what used to be used to calculate the humidity based on the difference between a dry thermometer and a one with a wet bulb.

A chart like this one (http://www.achrnews.com/NEWS/2003/48/Files/Images/94670.gif) found here http://www.achrnews.com/articles/air-side-diagnostics-and-service
will tell you the minimum temperature you could expect.  Bear in mind though that it will take a lot of air flow to keep the temperature down to that point.

[Atokatim]

Does anyone have a recommended company where I can order these cooling pads?  Is there any other material that I can use that is much more readily available like at my local Walmart or a similar store?  My local Home Depot or Lowes had no idea what these pads were.

[Frank S]

Does anyone have a recommended company where I can order these cooling pads?  Is there any other material that I can use that is much more readily available like at my local Walmart or a similar store?  My local Home Depot or Lowes had no idea what these pads were.

Do you have a WW Grainger nearby?

[Atokatim]

Closest one is about 1.5 hours away

I have an idea I am going to see if it works.  I think taking 2" wide strips of cotton cloth or gauze and overlapping them a little leaving room for them to "flap" open to let air pass through may work enough for what I need.  I go to work tomorrow so anything I can find today would be great!  I am fixing to run by walmart and see if there is any type of material that may absorb water and hold up to what I am trying to do with it.

[bob golding]

 polyester felt with a few drip tubes so the water soaks into the felt with a fan behind it? mount the felt on some hardware cloth. ,with a small pupm to circulate the water.

look up "MTD solar"  for the system i got the idea from.

[Atokatim]

I have found this on Amazon and was wondering if this would be good to start with or should I just buy the "right" stuff the first time?

http://www.amazon.com/Research-7130-36x12-Cooler-Roll/dp/B000BOAC0S/ref=pd_sbs_misc_21

For the price, I don't think it could hurt to try it.  I never could find a material to work for what I need.  The only thing I could think of was Spanish Moss (found in the gardening area of Home Depot) made into a pillow from a garden sheet made from polyester.  Did not get any though since I was not sure if it would work or not.

[Frank S]

this one on the same web site is less costly and a direct replacement for the old swamp coolers
 but the one you selected is probably more efficient
 fluffed cotton is highly absorbent but at the same time does not release moisture as readily as wool
 I guess times must have really changed or maybe it is just the region you are in because every home- depot of Lowes I ever visited had the pads 

[Atokatim]

I found a company close to my work that can get the Aspen pads in 1 day.  I went ahead and ordered 2 pads to tinker with.  Just got my pump in today as well!  Now I need a 12 volt heater blower fan from a vehicle and I will be set.

[WindriderNM]

There are synthetic pads that come in roles that can be cut to size. Home depot ect. Have them in NM. Check them on line