Abstract: Apparatuses are described for cooling the rotors of, improving the sealing of, and improving the power efficiency of twin-screw pumps. Such methods include (1) injecting liquid onto the rotor and into the rotor chambers at the point of greatest temperature accumulation, (2) implanting a heat transfer device within the rotor enclosure that can transfer heat outside of the rotor enclosure, and (3) injecting liquid into rotor chambers via energy recovery devices which reduce the total power consumption of the system.