Evaporative cooling operates
by harnessing the evaporation of water. The technology is primarily used in
regions with low humidity. The technique works by passing air over pads that
are saturated with water, which results in the evaporation of water from the
pads into the forced air. Temperature reductions of 15 to 40 degrees Fahrenheit
can be obtained this way. The air is directed into a building, forcing warmer
air out the windows.
Ancient Technology
Fresco paintings from ancient Egypt depict
slaves waving fans over containers of water. This appears to be the earliest
recorded use of evaporative cooling. Wealthy citizens of Rome
during the Roman Empire had water circulated
through their walls. The common people hung wet mats over their doors for
cooling.
Other Early Applications
Cooling towers were constructed in medieval
times. The towers were designed to trap wind and funnel it past water before it
entered a building. This method is believed have to have been developed in Persia. Water
evaporative cooling was used in New England
textile mills during the 1800s.
Willis Havillard Carrier
Willis Carrier was born in 1875 on a small
farm in Angola, New York. Carrier’s
mother taught math and problem-solving skills to her son. Carrier graduated
from Cornell University with a master’s degree in
engineering. From there, Carrier went to work at Buffalo Forge Co., which
manufactured heaters, air exhausts and blowers. Carrier was appointed head of
the company’s experimental science department.
Apparatus for Treating Air
Carrier was assigned the task of controlling
the humidity in a Brooklyn printing plant.
Carrier gained an understanding of the
relationship between the dew point, humidity and temperature while waiting for
a train one evening. The young engineer designed a system that controlled
temperature and humidity.
Southwestern United States
Residents of the U.S. Southwest tried various
methods to combat summer heat. In the 1920s and 1930s, people hung wet sheets
to capitalize on the evaporation process. Others risked pneumonia by sleeping
in wet sheets with electric fans blowing on them.
Swamp Coolers
Several designs of evaporative cooling devices
were tested in the Southwest. Until the 1960s, the swamp cooler was
predominant. The swamp cooler used aspen pads to contain the water for
evaporation. A swamp cooler was demonstrated in Phoenix at the Adams Hotel in 1916. Two
professors at the University of Arizona experimented with methods to improve
performance in evaporative coolers, and in 1939, they published instructions
for cooling homes in Arizona.
Recent History
Around the time of the professors’
instructions, the Emerson Company began mass production of evaporative coolers.
Other companies soon entered the market. By 1939, drip coolers were being used
at businesses and homes throughout the Southwest. Many companies were
manufacturing evaporative coolers by the 1950s, and the market had expanded to
include other parts of the United States,
Canada and Australia.
Advances continued on the technology. Improved pads reduced some issues such as
the amount of power needed to push the air. However, the newer pads created the
need to use recirculating systems to wet the pads. This in turn led to problems
that affected unit size and location. Use of units that do not recirculate is
one possible solution, but this increases water consumption.
