Which of the following compressor types uses slide valves to vary capacity?

The screw type compressor is known for its ability to vary capacity using slide valves. This design features two intermeshing rotors that compress the refrigerant as it moves through the unit. The incorporation of slide valves allows for the adjustment of the amount of refrigerant being compressed, enabling the compressor to maintain efficiency and provide better control over the system's cooling capacity based on demand. This variable capacity operation is particularly advantageous in applications where load conditions fluctuate, allowing for energy savings and enhanced performance.

Other compressor types, such as rotary, centrifugal, and reciprocating, generally employ different mechanisms for capacity modulation. For example, rotary compressors often use varying designs that do not include slide valves, while centrifugal compressors typically adjust their capacity through speed control or inlet guide vanes. Reciprocating compressors might use unloading mechanisms instead of slide valves to achieve capacity modulation. Thus, the ability of screw type compressors to utilize slide valves distinctly sets them apart in their operational capacity management.