IQS Newsroom Articles on Chillers
About Chillers and Chiller Manufacturers
Including: Industrial
Chillers, Liquid Chillers, Portable
Chillers, Water
Chillers & Air
Cooled Chillers.
Chillers are refrigeration systems that chill liquids such as water,
oil, brine, alcohol, chemicals and beverage or food ingredients for
industrial applications. With design and construction very similar to
that of air conditioners, liquid chillers range vastly in size and
design and may be fabricated as small, localized units for small
applications or as large central chillers combining many heat
exchangers and external cooling towers which span an entire facility.
These industrial chillers
cool products, mechanisms and factory machinery in processes such as
plastic injection molding, blow molding, metalworking, welding, die
casting, chemical and pharmaceutical processing, food and beverage
processing, lab equipment, gas cooling and lasers. Chocolate, for
example, may be run through a liquid cooler to in order to regulate the
chocolate's temperature for the next stage of processing, or to keep it
from burning. Water chillers continually cool water which is used in turn to cool laser equipment, while portable chillers and air cooled chillers are used in a variety of facility cooling systems depending on specific design requirements. Liquid coolers are typically recirculating chiller systems which recycle the same refrigerant liquid within a closed loop.
Chillers have four main stages: the evaporator, the
vapor compressor, the condenser and the expansion valve. These stages
are designed to recirculate the refrigerant through gas and liquid
stages. Initially, a cold refrigerant in gas form passes over heat
exchanger tubes containing the hot liquid which needs to be chilled.
The refrigerant absorbs the heat lost by the liquid, condensing some of
the vapor into a liquid. A vapor compressor compresses the liquid-gas
refrigerant into a high pressure, high temperature gas. The gas then
moves into the condenser coil over which ambient air blows. The air,
moved by one or more fans, removes heat from the gas, which causes it
to condense into a high pressure, warm temperature liquid. The liquid
passes through the expansion valve where a large pressure drop occurs,
turning the liquid into a very cold mist. The mist returns to the heat
exchanger, and the whole process begins again. Many types of toxic and
non-toxic refrigerants may be used in chillers; toxic refrigerants
include chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs)
and halomethanes such as R-22; these substances have very low boiling
points, enabling them to change their physical state from liquid to
vapor easily. Non-toxic refrigerants include water, brine, liquefied
propane gas and CO2.
Four styles of vapor compressors are used: reciprocating,
or piston, style compressors; scroll compressors; screw driven
compressors and centrifugal compressors. A scroll style compressor uses
two interleaved scrolls, one which is stationary and one which rotates
about the other to create a pump. A piston style, or reciprocating
compressor rotates a shaft that is curved like a crankshaft, creating
pressure in the piston cylinder. Screw compressors contain a single
rotating screw element which creates a vacuum as it rotates.
Centrifugal compressors use inertia to separate vapor molecules from
the air. Scroll compressors are usually more efficient than piston
compressors, but both are very reliable and widely used in the
refrigeration industry. Condensers come in three types. In air cooled
condensers, air circulates around tubes containing the refrigerant,
contributing to the condensation of the refrigerant. These condensers
are used in instances where water is unavailable. Water cooled
condensers, also called "shell" or "tube" condensers, utilize water to
condense the refrigerant. Water circulates through the tubes around
which the refrigerant is introduced, causing condensation of the
refrigerant on the outside of the tubes. In evaporative cooled
condensers, water is sprayed onto tubes containing the refrigerant. The
evaporation of the water causes the condensation of the refrigerant
within the tube. Large chillers used for high-volume industrial
applications often include a cooling tower at this stage, allowing
condensed liquid refrigerant to cool in a tank by various means of air
and water cooling.
Halomethanes R-12 and R-22 were the most commonly used
refrigerants up until the 1980's, and other similarly toxic
refrigerants such as Freon, CFCs and HCFCs continue to be used today.
As concern has risen in manufacturing and legislative sectors over
global warming, ozone-depleting substances such as Freon, halomethanes
and CFCs have been banned or discouraged. Disposal of toxic substances
such as Freon is hazardous to the environment, and CFCs used in
refrigeration have contributed to significant depletion of the Earth's
ozone layer. As the refrigeration and chiller industry advances,
more chiller manufacturers are using non-toxic refrigerants such
as ammonia, brine and pure water. Centrifugal vapor compressor
technology and other types of high efficiency vaporizing coolant
systems achieve more efficient cooling physically, without as great a
need for low-boiling chemicals.
Chiller Types
- ,
the most common chiller type, require little maintenance. However,
because of the need for high condensing temperatures ranging from 120° F
to 140° F, air cooled chillers require more power to operate.
- consist of air handling units fitted with chilled water
coils and are utilized in air condition systems.
- are
used to remove heat from an area.
- operate
year-round and are designed to provide specific, capacity-matched cooling
protection and proper temperature/water flow. Dedicated-process chillers
are the best choice for medical applications.
- are uncommon but highly efficient liquid chillers.
Evaporative chillers maintain the lowest condensing temperatures,
which range from 85° F to 105° F.
- provide
process cooling using a secondary fluid.
- are
often installed outside and are available in centralized and modular
designs. HVAC chillers are used in industrial and commercial environments.
- are
refrigeration systems that are used to chill various liquids in industrial
settings.
- are
refrigeration systems that remove heat from various liquids.
- Liquid coolers are typically recirculating chiller systems which recycle the same refrigerant liquid within a closed loop.
- lower
the temperature of coolant that is used in the cutting zone and recirculate
it back to the machine tool in a closed-loop system.
- are
self-contained chillers with higher pressure pumping, temperature stability
and microprocessor controls.
- are
self-contained units and are useful in small and/or dedicated applications.
- constantly
circulate coolant in a closed loop, retaining high efficiency without
wasting water.
- consist
of a compressor, condenser and chiller with internal piping and controls
all contained within a single unit. The term "water chillers" refers
also to an overall package that includes a refrigeration plant, water
chiller and air or water cooled condenser.
Chiller Terms
- The surrounding environment, including
temperature, pressure and/or humidity, coming into contact with a system
or component.
- Mineralized water consisting of sodium chloride, metallic
and/or organic contaminants.
- A measurement unit reflecting the
amount of heat needed to change the temperature of one pound of water
one degree Fahrenheit.
- Tube located between the condenser and evaporator
that manages the refrigerant flow.
- A chilling system that is self-contained.
A central chilling system has more than one unit and more than one compressor
but no pump tank set.
- A gas consisting of chlorine,
fluorine and carbon that has been used as a refrigerant in such items
as liquid
chillers. CFCs cause ozone depletion, because they do not break down
upon release into the atmosphere, but mix with ultraviolet light to create
carbon dioxide, and eventually ozone-eating chlorine radicals.
- The
measurement of a refrigeration system's efficiency that compares
the system's cooling ability
with the heat input necessary to attain such cooling. COP is calculated
by dividing a system's cooling ability by the system's heat
input and is expressed in BTU/hr.
- A device that
increases pressure on a gas through the act of pumping. Compressors are
responsible for the compaction of
the vaporized refrigerant to a pressure level suitable for liquification,
which occurs in the condenser.
- A device that removes
heat via forced air, water coil, etc., in order to convert a high pressure
gas into a lower pressure liquid.
Condensers remove heat from the compressed vaporized refrigerant, at
which point, the refrigerant returns to a liquid state.
- The
central part of a refrigeration system in which the system is operated
and maintained.
- A liquid used to remove heat.
- Indicates
the efficiency of an air conditioner or cooling system by comparing the
amount of energy needed
to produce cooling with the quality of the system's cooling ability
and is calculated by dividing the system's BTU by its wattage.
For example, if a cooling system maintains 20,000 BTUs and uses 1,500
watts,
the system's energy efficient rating would equal 13.3.
- Consists of a tube inside which the refrigerant soaks
up heat from it surroundings, boils and changes to a vapor.
- Mechanism located between the evaporator and
condenser that controls the refrigerant flow into the evaporator and
controls the temperature of the evaporator.
- Removes moisture and contaminants from vaporized
refrigerants.
- A device that
transfers heat from one fluid to another without mixing the fluids. (www.heatexchangers.org)
- A substance containing
chlorine, fluorine, carbon and hydrogen that is used as an alternative
to CFCs
as a refrigerant and a propellant. HCFCs produce fewer effects on than
ozone layer than CFCs do.
- A substance containing hydrogen, fluorine
and carbon that is used to replace CFCs and HCFCs because of HFCs lack
of effect on the ozone layer. HFCs produce no ozone depletion because
the substance does not contain chlorine, which breaks down the ozone
layer.
- A process that utilizes light to cool atoms to
a very low temperature.
- A molecule containing three oxygen atoms that absorbs ultraviolet
radiation in the stratosphere. Ozone also remains a harmful component
of smog and can contribute to lung damage and respiratory problems.
- A relative measurement of a substance's
negative effect on the ozone layer as compared to the effects of CFC-11,
which has an ODP of 1, on the ozone. For instance, a substance with an
ODP of 2 can potentially cause approximately twice the ozone depletion
as CFC-11 could.
- Also referred
to as the stratospheric ozone, it is the protective atmospheric layer
in the stratosphere, located 12-30
miles (20-50 kilometers) above sea level, in which ultraviolet radiation
is absorbed.
- The storage area for condensed liquid refrigerants.
- Liquids that produce cooling upon evaporation.
- Unit equal to 12,000 BTUs that refers to the
size of the chiller unit.
- A window in a refrigeration system through which
specialists can view the inner workings of the system.
- Mechanism
in a refrigeration system that controls the flow of refrigerant, especially
into the expansion valve.
- The
total amount of carbon dioxide that a refrigeration system can produce
throughout its lifetime.