Water Chillers are used in many applications to cool or chill fluids. These applications can include, but are not limited to, manufacturing processes and nuclear power plants. Water chillers can circulate up to two hundred tons of water at a single time, providing enough air conditioning power for entire skyscrapers or industrial facilities, or cooling huge pieces of machinery.
What is a Water Chiller?
A chiller is a mechanical refrigeration device, like an air conditioner, except that it cools a fluid (usually water) instead of cooling air.
- When a large air conditioner is required it is sometimes more feasible to use one large chiller instead of many small air conditioners.
- Chillers are also used wherever there is a need for cooling a fluid such as a chemical process or for plastics molding.
- To simplify the concept of a chiller you should compare it to a drinking fountain where you get cold "chilled" water.
What are the major components of a water chiller?
A chiller consists of a few major components. A compressor, an evaporator heat exchanger, a condenser heat exchanger, an expansion valve or two and some piping and controls are the basics.
- Compressors are usually reciprocating, scroll, centrifugal, or rotary screw types.
- The evaporator heat exchanger is usually of shell & tube constructions and is the exchanger where chilled water would be produced.
- The condenser heat exchanger can be either air-cooled, a coil or coils and a fan or fans, or water-cooled, another shell & tube heat exchanger cooled by cooling tower or other water.
How does the water chiller produce chilled water?
A chiller removes heat from a place where it is not needed or wanted and moves it to a place where it doesn't matter.
- A chiller produces cold water by the transfer of heat from entering water to refrigerant in the evaporator heat exchanger.
- A typical chiller would for example chill 55°F EWT, (entering water temp.), down to 45°F LWT, (leaving water temp.).
- The refrigerant would then carry the heat to the condenser for it to be removed to the environment via an air-cooled coil or water-cooled heat exchanger.
- If a cooling tower cools a water-cooled heat exchanger, the cooling tower will ultimately reject the heat to the environment.
- Once the refrigerant leaves the condenser heat exchanger, it will be compressed and the cycle continues.
What is the difference between a water chiller and a cooling tower?
A cooling tower is used to cool water instead of chilling it. Cooling towers use the evaporative cooling effect and transfer heat to the environment.
- Generally, water is dropped through a fill material while air is moved across the fill, transferring heat from the water to the air.
- The major component of a cooling tower is a fan to move the air across the fill material. Cooling towers work for cooling higher temperature water or fluids.
- A typical cooling tower would for example cool 95°F EWT down to 85°F LWT.
- Cooling towers are often used in conjunction with water-cooled chillers, but have many stand-alone uses as well.
How do I know if I need a water chiller or a cooling tower?
Depending on the application and operating conditions, chillers and cooling towers both have a place and design applications for which they are best.
- Cooling towers are most effective at LWT temperatures of 75°F and higher, while you would most likely need a chiller for LWT of 75°F or less.
- For LWT temperatures of 65°F and lower, cooling towers would likely not be an option, only a chiller can produce LWT of 65°F and lower.