For a Helical Rotor Design rotary refrigeration compressor, which of the following statements is true?
a. The compressor consists of three opposing grooved rotors
b. The driving rotor has less helical lobes than the driven rotor has flutes
c. The vapour is drawn in via the closed space between the driving rotor and the casing
d. The cylinders around the rotor screws must be considerably larger in diameter than the screws
e. The compressor is reversible, to allow it to be used in heat pump applications
Answer: B