swamp-cooler - how does it work?

Hello
anyone can explain me how a swamp-cooler works?

If you don't know what is it...
http://www.hoodride.com/Projects/Cori/cori7.jpg

It's this big thing to make the car fresh :D

I think this is the principle:

We use evaporative coolers to cool our homes in the Southwest. This works very well because the air here is so dry. When the humidity goes up, they don't work as well, since the air is already saturated with moisture.

The priciple: When water evaporates, it absorbs heat from the air.

A large volumn of air is directed through a pad soaked with water. As it passes through the pad, much of the water evaporates, absorbing heat, and dropping the air temperature at the same time. The "now much cooler" air is directed into the cars interior.

Guess those wont work here in florida huh, we had one at our house in cali, worked real good

I remember those things being sold at VW dealers in the 60's SOme were to contain ice and the cheaper units just redirected air thru a trubine right at your face. Some "Deluxe" models would have directional venting to let eveybody get a blast....Woo Hoo.

So alapimba - is that little round port on the side for water filling?

There are units that cool by way of pressure differential also.
Similar to those intake air coolers. The compressed hot air is expanded and therefore cools down before entering the manifold.

Like transferring air from a filled to an empty cylinder.

The full one will cool off as it empties, the one being filled will heat up as it fills.

Someone, maybe JC Whitney, used to sell one that was a console you mounted under your dash (sort of like the underdash ac units) but they were the poor-mans ac unit. You filled the hooper with ice, and a fan blew over the ice into the car. It doubled as a drink cooler. :D :D

I think they lasted about a few months, then you never heard of them again.

Don

The ice units dont work very well since the surface area of the ice is relatively small and the ice melts quickly.

A swamp cooler works by the heat of vaporization of water...it takes roughly 8700 BTUs to vaporize one gallon of water. The rate of evaporation is related to the surface area of the evaporator pad, the water temperature, the air humidity, and the air flow over the pad. As a reference, one ton of airconditioning is about 12,000 BTU/HR or about 3.5KW. Note that the one ton of air conditioning is a time-based figure while the swamp cooler reference is not time based....but IF you evaporated about 1 1/2 gallons per hour, then you would have about the equivalent of one ton of airconditioning in your swamp.

The smaller, car window units are limited to the pad size so their volume evaporated is relatively small....but better than nothing.

As a side note, the desert water cooler bags seen hanging on the front of cars in the old days and the blanket covered canteens the cowboys had worked the same way...the exterior was moistened and the air evaporation pulled heat away from the container. In fact, in the old days, people slept outside in the SouthWest and hung water soaked sheets over a line and slept down wind from them for the cooling effect....the first swamp coolers.

mike in tucson

Dang Robot, You must be a native. I was wondering when somebody would bring out the Water bag and wet sheet stories.

Don't forget, somebody had to get in the middle of the night to re-wet the sheets.

Nitro...actually I dislike swamp coolers...it makes everything rust. In our previous shop, if you cut a piece of metal, it was rusty in a day or two from the swamp cooler's affect on the humidity. Now, we are 100% air conditioned and have had bare bodies (cars, not women) in our shop for 3 years with zero rust. Of course, the down side to a/c is the electric bill.

mike in tucson

I hear ya....I am dissappointed though. I was gonna drive down and see these "bare bodies". Until you 'splained they were cars.....LOL.