Chiller System
Chiller systems may be small, compact and
portable units, or big, centralized systems integrated into a large facility. Chiller systems designed for building temperature control are most likely continuous-duty, meaning they are recirculating chillers that operate 24 hours a day. Some chiller systems function as air conditioners and are able to efficiently and inexpensively cool large commercial buildings like schools and office buildings, while others are employed in industrial facilities for specific temperature control applications. The medical, manufacturing, pharmaceutical, food and beverage and laboratory industries all use chiller systems to cool newly formed products or machinery that are heated as a result of a manufacturing process. Plastic molding, metal working, welding, die casting, chemical processing, breweries, lasers and printing presses all use various chiller systems to improve their product, maintain safe temperatures within the facility or decrease processing time.
All chiller systems are divided into four main stages, which 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, then condenses 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. Chillers can use 4 different types of
compressors: reciprocating, scroll,
screw and
centrifugal. They also differ in cooling method for the condensers-
air-cooled, where cool air circulates around tubes containing the refrigerant, water-cooled, which circulate water around the tubes, and evaporation-cooled condensers, where water is sprayed on the tubes to evaporate and cool the refrigerant in the same way that sweat cools the body.
