Twin oil-injected rotary screw compressors have a proven track record with industrial refrigeration applications. Low thermal growth of all compressor components contribute to compressor reliability and longevity.
The geometric profile of the rotating rotors is difficult to visualize. If you consider the male rotor as the pistons and the female rotor as the cylinders, it is easier to relate the compression process to a reciprocating compressor. As the male lobes and female flutes unmesh, an empty cylinder is created, drawing in suction gas through the synchronized opening on the rotor suction face. As rotation continues, the suction and discharge rotor faces are sealed off, trapping the gas in the cylinder and transferring the rotor wrap position. As rotation continues further, the male lobe rolls into the female flute and internally reduces the contained volume. The location (including size and shape of the discharge port) of completed compression at which the gas is allowed to exit is called the volume index ratio (Vi).