What is a Water Chiller?
A chiller is a mechanical refrigeration machine similar to an air conditioner except that it cools a fluid (usually water or glycol) 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 and pump the chilled water to various air handlers in the building. Chillers are also used to cool manufacturing processes to include chemical processing facilities, plastic molding machines, breweries, distilleries, pasteurizers, or any other machine that requires cooling to operate.
What are the Major Components of a Water Chiller?
A “chiller” consists of a few major components: compressors, an evaporator heat exchanger, condenser heat exchangers, expansion valves, and some piping and controls are the basics. Compressors are usually of reciprocating, scroll, centrifugal, or rotary screw types. The evaporator heat exchanger is usually of shell & tube or all stainless steel brazed plate. The condenser heat exchanger can be either air-cooled via a condenser coil and fans or water-cooled via another heat exchanger cooled by a cooling tower or other condenser water source.
How does the Water Chiller Produce Chilled Water?
A chiller removes heat from a circulating fluid and discharges it to the ambient air. 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 to transfer heat to the environment. Generally water is dropped through a fill material while air is moved across the fill. The evaporative cooling effect transfers 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 well for cooling higher temperature water or fluids. A typical cooling tower would 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 they are best used for. 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. Typically, only a chiller can produce LWT of 65°F and lower. If you are unsure, give us a call and our engineering department will assist you in the selection of the right machine for your application.
Why Should I Buy a Used Chiller, Cooling Tower, or Other Piece of HVAC or Related Equipment?
1. To save time.
- Depending on the type of chiller and manufacturer, new equipment lead times can easily be weeks to months. Can you afford to do without cooling for that long? Used and surplus chillers, cooling towers, heat exchangers, packaged ac units, and other hvac and related equipment is available, usually for immediate shipment.
2. To save money versus buying new.
- Quality late model used and unused surplus is available for significant savings versus buying new.
3. To save money versus renting.
- If you are considering a recurring or rental period of more than a month you should investigate the possibility of buying a used chiller in lieu of renting. A quality used chiller can often be purchased for less than you would spend renting. Not to mention the added security of having a machine on hand should the need arise again in the future.