Chiller
[2][3] Chilled water is used to cool and dehumidify air in mid- to large-size commercial, industrial, and institutional facilities.
A typical chiller for air conditioning applications is rated between 50 kW (170 thousand BTU/h) and 7 MW (24 million BTU/h), and at least two manufacturers (York international and LG) can produce chillers capable of up to 21 MW (72 million BTU/h) cooling.
[5][6] Chilled water temperatures (leaving from the chiller) usually range from 1 to 7 °C (34 to 45 °F), depending upon application requirements.
Large chilled water hoses are used to connect between rental chillers and air conditioning systems.
[8] In industrial applications, chilled water or other coolant liquid from the chiller is pumped through process or laboratory equipment.
They are often used in the plastic industries, injection and blow molding, metalworking cutting oils, welding equipment, die-casting and machine tooling, chemical processing, pharmaceutical formulation, food and beverage processing, paper and cement processing, vacuum systems, X-ray diffraction, power supplies and gas turbine power generation stations (see Turbine inlet air cooling#Vapour compression chiller), analytical equipment, semiconductors, compressed air and gas cooling.
They are also used to cool high-heat specialized items such as MRI machines and lasers in hospitals, hotels, and campuses.
Chilled water is used to cool and dehumidify air in mid- to large-size commercial, industrial, and institutional (CII) facilities.
Whenever a chiller's heat rejection can be used for a productive purpose, in addition to the cooling function, very high thermal effectiveness is possible.
Using electric motors in a semi-hermetic or hermetic configuration is the most common method of driving the compressors since electric motors can be effectively and easily cooled by the refrigerant, without requiring fuel supply or exhaust ventilation and no shaft seals are required as the motor can operate in the refrigerant, reducing maintenance, leaks, operating costs and downtime, although open compressors are sometimes used.
With evaporative cooling heat rejection, their coefficients of performance (COPs) are very high; typically 4.0 or more.
Common refrigeration compressors include reciprocating, scroll, screw, or centrifugal.
In recent years, application of variable-speed drive (VSD) technology has increased efficiencies of vapor compression chillers.
The first VSD was applied to centrifugal compressor chillers in the late 1970s and has become the norm as the cost of energy has increased.
Industrial chillers typically come as complete, packaged, closed-loop systems, including the chiller unit, condenser, and pump station with recirculating pump, expansion valve, no-flow shutdown, internal cold water control.
Compressors can be of two types - scroll and screw depending on the budget and the performance expected from a chiller.
[citation needed] Most industrial chillers use refrigeration as the media for cooling, but some rely on simpler techniques such as air or water flowing over coils containing the coolant to regulate temperature.
[11] Important specifications to consider when searching for industrial chillers include the total life cycle cost, the power source, chiller IP rating, chiller cooling capacity, evaporator capacity, evaporator material, evaporator type, condenser material, condenser capacity, ambient temperature, motor fan type, noise level, internal piping materials, number of compressors, type of compressor, number of fridge circuits, coolant requirements, fluid discharge temperature, and COP (the ratio between the cooling capacity in RT to the energy consumed by the whole chiller in kW).
Other important specifications include the internal water tank size and materials and full load current.
Additional features include emergency alarms, hot gas bypass, city water switchover, and casters.
[10] Demountable chillers are also an option for deployment in remote areas and where the conditions may be hot and dusty.
Larger chillers will typically require an array of sound attenuators sometimes known as a silencer bank.
There are several environmental factors that concern refrigerants, and also affect the future availability for chiller applications.
