EC SERIES
EVAPORATIVE COOLER
What is Evaporative
Cooling
Since ancient times, evaporative cooling has
been used as an inexpensive and simple method of
providing cooler air temperatures. Heat is absorbed whenever water is evaporated and
converted to water vapor. Evaporative cooling is essentially
adiabatic, following a constant wet bulb line, with no change in total heat. By passing air through or around a wetted surface, sensible
heat is removed from the surrounding air in the vaporization
of the water. In turn, the added water vapor increases
the latent heat and the relative humidity, but retains
total heat at a constant value. In contrast to
compressing a refrigerant, evaporative cooling requires no mechanical work or energy and
operates at considerably less cost than cooling by refrigeration.
Hastings Evaporative Cooler
Hastings evaporative air coolers provide fresh
air which is continuously drawn through special wetted 12" evaporative media. The unique crossfluted design of the media induces highly turbulent
mixing of air and water for optimum heat and moisture transfer.
Water flows through the length of the distribution header, is jetted up through small
holes spaced along the pipe, impinged on the larger cover pipe and transmitted to the
media as a fine water curtain. The media is designed so that water is constantly directed
to the air entry side. This results in cooling efficiencies, up to 90%. It also allows
greater face velocities without water carryover.
Two basic media are available on all EC
Series coolers. The standard media is made from a special cellulose paper, impregnated
with insoluble anti-rot salts and rigidifying saturants. Optional media made from large
glass fibers bound together by inorganic, noncrystalline fillers and UL approved with a UL
900, Class 2 rating can be furnished. Both types of media have the unique crossfluted
design.
Evaporative Cooling
Considerations
As the total heat - Btuh content - of the
air in the conditioned space remains constant during the evaporative cooling process, any
decrease in sensible heat is countered by an increase in latent heat. In general, the use
of evaporative cooling for conventional air conditioning is limited to locations with
summer design wet bulb temperature of 70 degrees or less. However evaporative cooling can
be applied effectively in industrial and commercial applications with higher wet bulb
design temperatures.
HASTINGS EVAPORATIVE COOLER SECTION
Air Discharge View
HASTINGS EVAPORATIVE COOLER SECTION
Air Intake View
The primary indicator of the potential
effectiveness of evaporative cooling is the wet bulb depression during the peak hours.
Normally evaporative cooling will be practical with a wet bulb depression (entering dry
bulb temperature minus entering wet bulb temperature) of 20 degrees or more. While cooling
can be effected with smaller wet bulb depressions a greater number of air changes are
required as well as other application considerations.
Evaporative Cooling
Applications
1. Comfort Applications
Evaporative coolers are used extensively
for comfort air conditioning, rather than mechanical refrigeration, in areas with
relatively dry climate conditions. A large part of western United States falls in this
category. In locations having a summer design wet bulb temperature of 70 degrees or less,
evaporative coolers can be used for most comfort cooling applications.
2. Relief Applications
Relief cooling with evaporative coolers
can be effectively accomplished for industrial and hot, humid commercial environments with
practically no limitations as to design wet bulb temperatures. Many commercial and
industrial applications feature high internal sensible and latent loads, often accompanied
by large make-up air requirements. In most of these installations it is not economically
feasible to cool with mechanical refrigeration. As evaporative coolers have both low first
cost and low operating cost and in turn require 100 percent outside air, they can be used
most successfully to provide relief cooling for these applications.
Relief or comfort cooling using evaporative
coolers is accomplished in two ways. First by lowering the dry bulb temperature of the air
and secondly, by the movement of air over individuals. Generally comfort cooling for hot
industrial applications is achieved by either space cooling or spot cooling. Air
quantities vary dependent upon wet bulb depression and the internal heat source. In
addition to industrial comfort cooling and industrial process cooling, evaporative coolers
provide relief in such applications as laundries and restaurant kitchens. They have also
proven practical for greenhouse as well as animal barn and poultry house cooling. |
