A water chiller is a device used to lower the temperature of water. Most chillers use refrigerant in a closed loop system to facilitate heat exchange from water where the refrigerant is then pumped to a location where the waste heat is transferred to the atmosphere.
Vapor Compressor Chillers
Vapor compressor water chillers use a compressor to pump refrigerant which extracts unwanted heat from a process. The components of the system are the same as in the absorption type-we have an evaporator, a condenser, and an expansion unit. However, there is no absorbent medium in the unit.
Vapor Absorption Chillers
Unlike vapor compressor systems, vapor absorption chillers use a heat source to transport the refrigerant around the system for cooling. The components of the system are the same as in vapor compressor type chillers, but in place of the compressor, there is an absorber, a pump, and a generator.
The heat source can be heated by water or steam, the refrigerant can be a low Global Warming Potential (GWP) type like R-134a or R1234ze and the absorption medium can be a solution of Lithium Bromide or ammonia. The heated water or steam helps regenerate the adsorption solution.
Screw Chiller vs. Centrifugal Chiller
Centrifugal chillers are very dependable vapor compression cycle chillers ideal for medium to large scale cooling operations (from 150-6000 tons of refrigeration). They consist of the usual evaporator, compressor, condenser, and expansion device set-up but with additional rotating impellers, which compress the refrigerant and transport it around the system.
Screw chillers are vapor compressor chillers that use a screw compressor to transport the coolant through the system. Some key benefits are their compact installation, quiet operation, lower maintenance costs, and high energy efficiency. They are also ideal for high-rise buildings. At the same time, the maintenance of water chiller is also very necessary.
Both chiller types offer efficient cooling for facilities. However, ATO recommends using centrifugal chillers for high-volume cooling and screw chillers for dependable operation in facilities with space constraints.