Biomedical Engineering Reference
In-Depth Information
Fig. 2
Buffaloes under mist cooling system
clean; otherwise, fogging nozzles get clogged or
plug (Worely
1999
). A fogging system is effec-
tive in hot areas with low humidity. In an environ-
ment which is saturated with water, the droplets
cannot evaporate, and a 'steam bath' effect is
likely to be created (Bucklin et al.
1991
) .
Atomisers of different diameter help in conserva-
tion of water by regulating the water dispersion.
heat loss from the skin is inhibited (Jones and
Stallings
1999
). Use of mist system for cooling
cows and buffaloes was found to be economical
also (Aggarwal and Singh
2007
) . Figure
2
shows
a shed with mist cooling facilities.
If the misting system application is in an open
area, the cooling capability may be diminished
due to a lack of shade and the inability to mount
the mist system so that complete evaporation is
achieved. In these cases, adding fans to the misting
system design will improve its cooling capacity.
If there is no structure to mount to, the mist system
can be laid on the ground with the misting system
nozzles pointing directly upwards. Although this
is not the ideal design for a mist system, it can
provide relatively good results.
3.3.3 Misters
A misting system consists of a series of misting
nozzles placed in a sequence in tubing and pres-
surised to provide a fine spray of water droplets
between 15 and 50 mm in size. A mist droplet is
larger than a fog droplet. The animal is primarily
cooled by breathing in the cooler air. This system
is not very effective for humid environments,
because the mist droplets are too large to evapo-
rate before they reach the floor and the bed or feed
becomes wet (Shearer et al.
1999
) . Another com-
plication with misters is that if the system does
not wet the hair coat through the skin, an insulating
layer of air can be trapped between the water layer
and the skin. Therefore, the natural evaporative
3.3.4 Sprinkler-cum-Fan Cooling
An alternative to mist and fog systems is the
sprinkling system. This method does not attempt
to cool the air but instead uses a large droplet size
to wet the hair coat to the skin of the cow or
buffalo, and then water evaporates and cools the
hair and skin. Sprinkling is most effective when
