The following are design considerations for chillers.
a. Type of compressor: Although it varies from one manufacturer to another,
the type of compressors used and the associated range of chiller capacities
are generally as follows:
(1) Reciprocating compressors: 25- to 75-ton chillers
(2) Scroll compressors: 25- to 500-ton chillers (3) Screw compressors: 75- to 800-ton chillers
(4) Centrifugal compressors: 100- to 4,000-ton chillers
A chiller manufacturer’s representative should be consulted to determine
the appropriate type of chiller for each application.
b. Refrigerant: Refrigerants most commonly used in HVAC equipment fall into one of the following three categories: chlorofluorocarbon- (CFC), hydrochlorofluorocarbon- (HCFC), and hydrofluorocarbon- (HFC) based refrigerants.
In accordance with the Montreal Protocol, an international treaty administered by the United Nations Environment Programme (UNEP), which controls the consumption and production of ozone-depleting substances, CFC-based refrigerants, such as R-11 and R-12, are no longer produced due to their ozone-depletion potential (ODP). Today, CFC-based refrigerants are available only through stockpiled resources and are used to replenish refrigerant in existing equipment. HCFC-based refrigerants, such as R-22 and R-123, have a lesser ODP and are therefore not scheduled to
cease production until the year 2030. HFC-based refrigerants, such as R-134a and R-410A, do not have any ODP and are therefore not regulated by the Montreal Protocol.