Desert Diary
Physics/Coolers

   

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The swamp cooler is traditional in the Southwest (though, of course, the older tradition is to keep in the shade and pray for rain). The cooler works by drawing air through a moist pad; evaporation of water from the pad cools the pad and thus the air passing through. This works well in the dry months of May and June, but efficiency decreases radically during the summer monsoon due to the rising humidity and thus reduced rate of evaporation.

Another negative is the large amount of water used in this land of limited supply. Water utilities are strongly urging people to go to refrigerated air conditioning. This works similar to a refrigerator. A parcel of gas and its contained heat is compressed into a smaller space, making it hotter than the air around the outside part of the unit. This extra heat radiates away. When the gas is brought back into the building, the gas is allowed to expand back to its original volume, but since it has lost part of its heat, it now is cooler—refrigerated, in fact!

Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.

Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.

References

Web Resources

Swamp cooling explained