Which of the following are used to control the capacity of centrifugal refrigeration compressors:
1) unloaders
2) hot gas bypass
3) variable speed drives
4) suction throttling
5) variable inlet guide vanes
a) 1,2,3
b) 1,3,4
c) 2,3,4
d) 3,4,5
e) 2,3,5
Answer: D