BASICS For Refrigerant Chillers

There are two primary chiller types: absorption and refrigerant, which operate very differently. There are two primary types of refrigerant chillers, either air cooled and water cooled or centrifugal compressors.

Refrigerant chillers follow the Carnot Cycle, which has four main steps (See Diagram below):

1) Compression (compressor)

2) Condensing (condenser)

3) Expansion (expansion valve)

4) Evaporation (evaporator)

The compressor is the chiller system's heart. It takes the lower-pressure vaporized refrigerant coming out of the evaporator, compresses it to a higher pressure, and discharges it into the condenser.

Expansion valves: High pressure liquid refrigerant passes through expansion valves, reducing pressure and flashing to a gas within the evaporator, absorbing energy frm the chilled water.

The condenser is were the refrigerant rejects heat (energy) to the condenser water or air, causing refrigerant phase change from gas to liquid.

The evaporator is where the refrigerant removes heat (energy) from the chilled waters.

Engineered Systems magazine