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.