Which of the following compressors uses non-positive (variable) displacement to increase the pressure of a refrigerant?

The centrifugal compressor is recognized for its use of non-positive (variable) displacement to increase the pressure of a refrigerant. It operates by converting kinetic energy from a rotating impeller into pressure energy, which effectively compresses the refrigerant gas. As the gas enters the impeller, it is thrown outwards by centrifugal force, which leads to a decrease in velocity and an increase in pressure as it moves through a diffuser.

This dynamic mechanism allows centrifugal compressors to efficiently handle large volumes of gas with varying flow rates. Unlike positive displacement compressors, which move a fixed volume of gas with each cycle and thus have a constant flow rate, centrifugal compressors adjust their output based on the demand for refrigerant, making them particularly suitable for systems where refrigerant demand may vary.

Understanding the differences in compressor types is crucial for operating engineers, as it affects the selection and application of equipment in HVAC and refrigeration systems.