Chilled water is a commodity often used to cool a building's air and equipment, especially in situations where many individual rooms must be controlled separately, such as a hotel. The chilled water can be supplied by a vendor, such as a

public utility A public utility company (usually just utility) is an organization that maintains the infrastructure for a public service (often also providing a service using that infrastructure). Public utilities are subject to forms of public control and ...

, or created at the location of the building that will use it, which has been the norm.

Use

Chilled water cooling is not very different from typical residential

air conditioning Air conditioning, often abbreviated as A/C (US) or air con (UK), is the process of removing heat from an enclosed space to achieve a more comfortable interior temperature, and in some cases, also controlling the humidity of internal air. Air c ...

where

water Water is an inorganic compound with the chemical formula . It is a transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance. It is the main constituent of Earth's hydrosphere and the fluids of all known liv ...

is pumped from the chiller to the air handler unit to cool the air. Regardless of who provides it, the chilled water (between ) is pumped through an air handler, which captures the heat from the air, then disperses the air throughout the area to be cooled.How Stuff Works: How Air Conditioners Work-Chilled-water and Cooling-tower AC Units
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Site generated

As part of a chilled water system, the condenser water absorbs heat from the refrigerant in the condenser barrel of the water chiller and is then sent via return lines to a

cooling tower A cooling tower is a device that rejects waste heat to the atmosphere through the cooling of a coolant stream, usually a water stream, to a lower temperature. Cooling towers may either use the evaporation of water to remove heat and cool the ...

, which is a heat exchange device used to transfer waste heat to the

atmosphere An atmosphere () is a layer of gases that envelop an astronomical object, held in place by the gravity of the object. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A stellar atmosph ...

. The extent to which the cooling tower decreases the temperature depends upon the outside temperature, the

relative humidity Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation (meteorology), precipitation, dew, or fog t ...

and the

atmospheric pressure Atmospheric pressure, also known as air pressure or barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The standard atmosphere (symbol: atm) is a unit of pressure defined as , which is equivalent to 1,013. ...

. The water in the chilled water circuit will be lowered to the Wet-bulb temperature or dry-bulb temperature before proceeding to the water chiller, where it is cooled to between 3 and 6 °C and pumped to the air handler, where the cycle is repeated. The equipment required includes chillers, cooling towers,

pump A pump is a device that moves fluids (liquids or gases), or sometimes Slurry, slurries, by mechanical action, typically converted from electrical energy into hydraulic or pneumatic energy. Mechanical pumps serve in a wide range of application ...

s and electrical control equipment. The initial capital outlay for these is substantial and maintenance costs can fluctuate. Adequate space must be included in building design for the physical plant and access to equipment.

Utility generated

The chilled water, having absorbed heat from the air, is sent via return lines back to the utility facility, where the process described in the previous section occurs. Utility generated chilled water eliminates the need for chillers and cooling towers at the property, reduces capital outlays and eliminates ongoing maintenance costs. The physical space saved can also become rentable, increasing revenue. Utility supplied chilled water has been used successfully since the 1960s in many cities, and technological advances in the equipment, controls and trenchless installation have increased efficiency and lowered costs. The advantage of utility-supplied chilled water is based on economy of scale. A utility can operate one large system more economically than a customer can operate the individual system in one building. The utility's system also has back-up capacity to protect against sudden outages. The cost of such "insurance" is also markedly lower than what it would be for an individual structure. The use of utility supplied chilled water is most cost effective when it is designed into the building's infrastructure or when chiller/cooling tower equipment must be replaced. Commercial customers often lower their air conditioning costs from 10 to 20% by purchasing chilled water.Jacksonville Business Journal: July 11, 2003-JEA's cool idea can save by Chuck Day
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Chilled water storage

Water can also be chilled at night, where electricity is available at off-peak rates, then stored in a large, insulated tank until needed, the next day, for cooling.

References

External links

Chilled Water Plant Design and Specification Guide
{{HVAC Cooling technology Heating, ventilation, and air conditioning Mechanical engineering