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.
