What are Chiller Systems?

A chiller (cooling water circulation device) is a general term for a device that controls the temperature
by circulating a liquid such as water or heat medium as a cooling liquid whose temperature was
adjusted by the refrigerant cycle. In addition to maintaining the temperature of various industrial
devices and laboratory instruments, equipment, and apparatuses at a constant level, it is also used for
air conditioning in buildings and factories. It is referred to as a “chiller” because it is often used for
cooling.

How Does a Chiller Work?

In most process cooling applications, a pumping system circulates cool water or a
water/glycol solution from the chiller to the process. This cool fluid removes heat from the
process and the warm fluid returns to the chiller. The process water is how heat transfers
from the process to the chiller.
Process chillers contain a chemical compound, called a refrigerant. There are many types of
refrigerants and applications depending on the temperatures required but they all work on the
basic principle of compression and phase-change of the refrigerant from a liquid to a gas and
back to a liquid. The refrigeration cycle is the process of heating and cooling the refrigerant and changing it from a
gas to a liquid and back again.
The refrigeration cycle starts with a low-pressure liquid/gas mix entering the evaporator. In
the evaporator, heat from the process water or water/glycol solution boils the refrigerant,
which changes it from a low-pressure liquid to a low-pressure gas. The low-pressure gas
enters the compressor, which is compressed to high-pressure gas. The high-pressure gas
enters the condenser where ambient air or condenser water removes heat to cool it to a high-
pressure liquid. The high-pressure liquid travels to the expansion valve, which controls how
much liquid refrigerant enters the evaporator, thereby beginning the refrigeration cycle again.
There are two types of condensers used in chillers: air-cooled and water-cooled. An air-
cooled condenser uses ambient air to cool and condense the hot refrigerant gas back down to
a liquid. It can be located inside the chiller or can be remotely located outside, but ultimately
it rejects the heat from the chiller to the air. In a water-cooled condenser, water from a
cooling tower cools and condenses the refrigerant.

Types of Chillers:

Water-Cooled Chillers:

This is a type of system that sends wind to the heat exchanger and cools the refrigerant with
air. There is a built-in fan motor inside the chiller, and it is easy to install, but because
exhaust heat is generated in the room, exhaust equipment may be required in tight spaces.
The gas compressed with the freezer (compressor) is cooled by a condenser (radiator) and
liquefied. It is comprised of a refrigerant gas cycle and a circulating water cycle, and
refrigerant gas is used as a heat medium to cool the circulating water.
By passing liquefied gas through the expansion valve, the pressure is reduced, and it becomes
a cooling gas, and a water cooler (heat exchanger) exchanges heat with the circulating water
to cool the circulating water. Because there is no freezing or clogging, aquarium cleaning
maintenance is easy. Also, in the case of the air-cooled chiller, the heat of vaporization due to

the evaporation of rainwater lowers the temperature of the radiator when rainwater comes
into contact with the cooling tower when it rains, and because the temperature drops due to
the evaporation of rainwater around the air-cooled chiller, the cooling efficiency can be
maintained regardless of the rise in humidity, such that the cooling efficiency improves even
if the humidity is high.

Air-Cooled Chillers:

Air-cooled chillers actively absorb heat from process water; they then transfer this heat into
the air around the chiller unit. This type of unit is typically used in areas where additional
heat discharge is not an issue but instead works as a benefit. For instance, the additional heat
can be used to warm spaces during the winter for less money than traditional heating systems.
Air-cooled chillers offer the significant advantage of lower installation costs. Simpler maintenance
also results due to their relative simplicity as compared to water-cooled chillers. Air-cooled chillers
will occupy less space but will mostly reside outside a facility. Thus, the outdoor elements will
compromise their functional lifespan.

For the Maintenance

Common preventive maintenance for chillers typically involves cleaning, monitoring
temperature and pressure, and general system testing. Depending on the maintenance tasks,
technicians must perform them anywhere from daily to annually.
Chillers should also be tested for leaks, control operation, and water quality weekly. Items
such as load balances and limits can be inspected twice a year. A thorough cleaning, electrical
system inspection, and other maintenance tune-ups should be performed annually

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Conclusion:

Chiller operational efficiency will greatly impact your building operating costs. Ongoing
routine maintenance represents the minimum from the perspective of facility management.
Predictive maintenance and optimization of the chiller system require real-time operational
data. IoT has opened the door to new forms of chiller efficiencies.