Glossary

evaporator A component of the refrigeration system where cool, liquid refrigerant absorbs heat from air, water, or some other fluid, causing the refrigerant to boil.

expansion device A component of the refrigeration system used to reduce the pressure and temperature of the refrigerant to the evaporator conditions.

flash The process of liquid refrigerant being vaporized by a sudden reduction of pressure.

heat of compression The amount of heat added to the refrigerant vapor by the compressor during the process of raising the pressure of the refrigerant to condenser conditions.

helical-rotary compressor A type of compressor that uses two mated rotors to trap the refrigerant vapor and compress it by gradually shrinking the volume of the refrigerant.

hermetic compressor A type of compressor that has the motor sealed within the compressor housing. The motor is cooled by refrigerant.

hot gas bypass A method used to prevent evaporator freeze-up by diverting hot, high-pressure refrigerant vapor from the discharge line to the low-pressure side of the refrigeration system.

impeller The rotating component of a centrifugal compressor that draws refrigerant vapor into its internal passages and accelerates the refrigerant as it rotates, increasing its velocity and kinetic energy.

inlet vanes A device used to vary the capacity of a centrifugal compressor by “preswirling” the refrigerant in the direction of rotation before it enters the impeller, lessening its ability to take in the refrigerant vapor.

liquid line A pipe that transports refrigerant vapor from the condenser to the evaporator in a mechanical refrigeration system.

open compressor A type of compressor that is driven by an external power source, such as an electric motor or a turbine. The motor is coupled to the compressor crankshaft by a flexible coupling, and a seal is used to prevent refrigerant from leaking out of the compressor housing.

ported compressor A type of compressor where the refrigerant vapor enters and exits through ports—no valves are used.

positive-displacement compressor A class of compressors that works on the principle of trapping the refrigerant vapor and compressing it by gradually shrinking the volume of the refrigerant.

pressure–enthalpy chart A graphical representation of the properties of a refrigerant, plotting refrigerant pressure versus enthalpy.

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Trane TRG-TRC004-EN manual Glossary