Abstract: An open air cycle machine includes a compressor, a pair of heat exchangers, an expander, and a bypass system that can selectively recirculate the expanded, cooled airflow prior to entering the compartment being cooled. One of the heat exchangers is regenerative, and the bypass system directs the expanded airflow through the regenerative heat exchanger to further cool the compressed airflow prior to entering the expander. The bypass system includes a bypass duct and a mixer, and the mixer has a valve and a controller.

Abstract: A screw rotor device has a housing with an inlet port and an outlet port, a male rotor with helical threads, and a female rotor with helical grooves. The helical threads and helical grooves are designed to eliminate the blow hole leak pathway for multiple-pitch screw rotor devices as well as single-pitch screw rotor devices. The male rotor has a pair of helical threads with a phase-offset aspect, and the female rotor has a corresponding pair of helical grooves. The female rotor counter-rotates with respect to the male rotor and each of the helical grooves respectively intermeshes in phase with each of the helical threads. The phase-offset aspect of the helical threads is formed by a pair of teeth bounding a toothless sector.

Abstract: A screw rotor device has a housing with an inlet port and an outlet port, a male rotor, and a female rotor. The male rotor has a pair of helical threads with a phase-offset aspect, and the female rotor has a corresponding pair of helical grooves. The female rotor counter-rotates with respect to the male rotor and each of the helical grooves respectively intermeshes in phase with each of the helical threads. The phase-offset aspect of the helical threads is formed by a pair of teeth bounding a toothless sector. The arc angle of the toothless sector is a least twice the arc angle that subtends either one of the teeth. The helical grooves have a radially narrowing axial width at the periphery of the female rotor. The male and female rotors may include a buttress thread profile and may be limited in length to a single pitch.

Abstract: A screw rotor device has a housing with an inlet port and an outlet port, a male rotor, and a female rotor. The male rotor has a pair of helical threads with a phase-offset aspect, and the female rotor has a corresponding pair of helical grooves. The female rotor counter-rotates with respect to the male rotor and each of the helical grooves respectively intermeshes in phase with each of the helical threads. The phase-offset aspect of the helical threads is formed by a pair of teeth bounding a toothless sector. The arc angle of the toothless sector is a least twice the arc angle that subtends either one of the teeth. The helical grooves have a radially narrowing axial width at the periphery of the female rotor. The male and female rotors may include a buttress thread profile and may be limited in length to a single pitch.

Abstract: A screw rotor device has a housing with an inlet port and an outlet port and at least one pair of rotors. The rotors each have an identical number of threads (N), a buttress thread profile with a diagonal line, and a length that is either approximately equal to or less than a single pitch of the threads. The threads of the rotors intermesh as the rotors counter-rotate with respect to each other. The rotors can be twins or each one of the rotors can have different profiles.

Abstract: A screw rotor device has a housing with an inlet port and an outlet port, a male rotor, and a female rotor. The male rotor has a pair of helical threads with a phase-offset aspect, and the female rotor has a corresponding pair of helical grooves. The female rotor counter-rotates with respect to the male rotor and each of the helical grooves respectively intermeshes in phase with each of the helical threads. The phase-offset aspect of the helical threads is formed by a pair of teeth bounding a toothless sector. The arc angle of the toothless sector is a least twice the arc angle that subtends either one of the teeth. The helical grooves have a radially narrowing axial width at the periphery of the female rotor.