Very
often GCI customers have requirements for cooling water above
80°F. In these situations, GCI can furnish a cooling tower
or a fluid cooler, depending on the ambient air temperature, coolant
temperature requirement, and how the heat is to be rejected. Here,
we provide an overview of your choices.
GCI
does not manufacture either cooling towers or fluid cooler heat
exchangers. This gives us the ability to find the best option
for you. We design and build the tank/pump sets and pumping stations
that work with these units.
Cooling
Towers
Towers provide a means to reject heat through direct evaporation
of the cooling water used in the facility. Water cascades down
over a "wet deck" through which air is blown. In the
process, heat from the water is rejected to the atmosphere through
evaporation.
Because
the process water comes in direct contact with the atmosphere,
impurities can contaminate the water. Impurities already in the
water become more concentrated. Regular maintenance, therefore,
is very important. Cooling towers in northern climates require
that a tank be installed inside the building to eliminate the
possibility of water in the tower freezing, damaging the tower.
Fluid
Coolers
There are two types of fluid coolers. In both cases, the coolant
from the facility is piped through a coil where its heat is rejected
to the outside.
Evaporative
coolers use water to dissipate the heat. Water is re-circulated
in the unit, dripping across the coil containing the coolant.
A fan forces fresh air up through the coil. In the process, heat
is transferred from the coolant to the circulating water where
it is rejected into the atmosphere through evaporation. A small
amount of the cooling water is lost during evaporation and must
be replenished. A heater may be required to keep the circulating
water from freezing during winter. Since the coolant does not
come in direct contact with the atmosphere, no contaminants enter
the cooling circuit.
A
dry air cooler, on the other hand, has finned coils. Here, fans
mounted above the coil draw air across the coils removing the
heat into the atmosphere. Dry air coolers tend to be less efficient
than evaporative coolers so they require larger coils and fans.
They tend to operate at higher temperatures and produce less of
a temperature reduction.
In
both evaporative coolers and dry air coolers, the coolant is in
a closed system, so a glycol mix can be used. The coolers, however,
have no tank to store the coolant when not in use, so like cooling
towers, an indoor tank-pump set or pumping unit is required.
