Air Cooled Water Chiller

The compressor used in scroll water chillers also belongs to the category of positive-displacement, rotary compressors. It has two co-wound spirals or scrolls with one acting as the rotor while the other as a stater. The rotor does not actually rotate but moves eccentrically relative to the other. The refrigerant trapped between the scrolls is transported towards the center where the volume is progressively decreased.

Scroll chillers are typically used in small cooling load applications. To increase its capacity, one or more scroll compressors are used in one chiller package. In terms of efficiency, they have comparable COP to the screw types. When used in conditions with varying cooling loads, there are a number of refrigerant control methods available such as speed control and variable displacement control.

Also known as this type of chiller uses a screw compressor to provide mechanical work for its vapor compression cycle. A screw compressor is a type of positive-displacement, rotary compressor which typically uses two helical screws as rotors. Compression is made by trapping the refrigerant in the cavities between the threads of the rotor. The volume of these cavities progressively decreases which then increases the pressure.

Capacity-wise, screw water chillers are used for small to medium applications. Because of their high partial-load efficiency, they are used in applications with varying cooling load demands. Moreover, they do not develop surges when used at low loads, unlike the centrifugal and reciprocating types

This water chiller uses a reciprocating piston or plunger to draw and compress the refrigerant. Because of their nature of producing compression, they are also classified as positive-displacement compressors.

A reciprocating water chiller is now becoming an obsolete chiller technology because of the drawbacks of its compressor. Reciprocating compressors have a noisy operation, poor reliability, and short service life. The only advantage is their affordable cost.