A method of operating a refrigeration system includes initiating a compressor shutdown operation, determining a difference in a saturation temperature at a port of a compressor of the refrigeration system and an ambient temperature and comparing the difference in the saturation temperature and ambient temperature with a threshold. If the difference in the saturation temperature and ambient temperature is less than or equal to the threshold, a pump down operation is performed and if the difference in the saturation temperature and ambient temperature exceeds the threshold, a compressor shutdown operation is completed.

The present disclosure relates to a new breed of high performance compressors and associated vapor compression systems that can be used in wide ranging refrigeration, cooling and heating applications with significantly increased compressor isentropic efficiency, motor efficiency, reliability and longevity of the motor, the compressor pump and the system as a whole, as well as COP, heating capacity, and SEER of the new vapor compression systems utilizing the new high performance compressors. The design philosophy and modifications to the current configuration of rolling piston rotary compressor to arrive at the high-performance version of the same type will be readily applicable to other types of vapor compression compressors with only minor changes opening the way for adoption of the new design philosophy by the entire compressor industry resulting in serious reduction of carbon footprint for air conditioners, heat pumps and refrigerators worldwide.

The present disclosure relates to a new breed of high performance compressors and associated vapor compression systems that can be used in wide ranging refrigeration, cooling and heating applications with significantly increased compressor isentropic efficiency, motor efficiency, reliability and longevity of the motor, the compressor pump and the system as a whole, as well as COP, heating capacity, and SEER of the new vapor compression systems utilizing the new high performance compressors. The design philosophy and modifications to the current configuration of rolling piston rotary compressor to arrive at the high-performance version of the same type will be readily applicable to other types of vapor compression compressors with only minor changes opening the way for adoption of the new design philosophy by the entire compressor industry resulting in serious reduction of carbon footprint for air conditioners, heat pumps and refrigerators worldwide.

The present invention provides a composition containing a refrigerant having characteristics equal to or higher than those of R23. Specifically, the present invention provides a composition containing a refrigerant, wherein the refrigerant contains (a) at least one perfluorocarbon (PFC) selected from the group consisting of PFC-14, PFC-116, PFC-c216, PFC-218, PFC-c318, and PFC-31-10, and (b) an unsaturated compound.

The present invention provides a composition containing a refrigerant having characteristics equal to or higher than those of R23. Specifically, the present invention provides a composition containing a refrigerant, wherein the refrigerant contains (a) at least one perfluorocarbon (PFC) selected from the group consisting of PFC-14, PFC-116, PFC-c216, PFC-218, PFC-c318, and PFC-31-10, and (b) an unsaturated compound.

Disclosed is a direct-drive refrigerant screw compressor, having: a housing; a compression chamber in the housing; a pair of rotors, each rotor of the pair of rotors being rotationally disposed in the compression chamber and including an outer surface with a screw-geared profile; a fluid being disposed in the compression chamber, the fluid consisting of a working fluid for providing lubrication to each rotor; a first port extending through the housing and configured for directing the fluid toward the compression chamber; and when the compressor is activated, each rotor rotates and the fluid is distributed about each rotor to lubricate each rotor.

A variable capacity screw compressor comprises a suction port, at least two screw rotors and a discharge port being configured in relation to a selected rotational speed that operates at least one screw rotor at an optimum peripheral velocity that is independent of a peripheral velocity of the at least one screw rotor at a synchronous motor rotational speed for a rated screw compressor capacity. A motor is configured to drive the at least one screw rotor at a rotational speed at a full-load capacity that is substantially greater than the synchronous motor rotational speed at the rated screw compressor capacity. A variable speed drive receives a command signal from a controller and generates a control signal that drives the motor at the selected rotational speed.

A variable capacity screw compressor comprises a suction port, at least two screw rotors and a discharge port being configured in relation to a selected rotational speed that operates at least one screw rotor at an optimum peripheral velocity that is independent of a peripheral velocity of the at least one screw rotor at a synchronous motor rotational speed for a rated screw compressor capacity. A motor is configured to drive the at least one screw rotor at a rotational speed at a full-load capacity that is substantially greater than the synchronous motor rotational speed at the rated screw compressor capacity. A variable speed drive receives a command signal from a controller and generates a control signal that drives the motor at the selected rotational speed.

A condenser of a refrigeration cycle apparatus includes a first passage, a second passage, and a joint. The first passage connects to the compressor at a first end and is constituted of, at a second end, a first flat heat transfer tube including a plurality of passages thereof. The second passage connects to the expansion device at a first end and is constituted of, at a second end, a second flat heat transfer tube including a plurality of passages thereof. The joint joins the first flat heat transfer tube and the second flat heat transfer tube and bends a flow of the hydrofluoroolefin-based refrigerant between the first flat heat transfer tube and the second flat heat transfer tube. A length of the second passage is equal to or shorter than a length of the first passage. The joint is provided, inside thereof, with a hollow portion.

A condenser of a refrigeration cycle apparatus includes a first passage, a second passage, and a joint. The first passage connects to the compressor at a first end and is constituted of, at a second end, a first flat heat transfer tube including a plurality of passages thereof. The second passage connects to the expansion device at a first end and is constituted of, at a second end, a second flat heat transfer tube including a plurality of passages thereof. The joint joins the first flat heat transfer tube and the second flat heat transfer tube and bends a flow of the hydrofluoroolefin-based refrigerant between the first flat heat transfer tube and the second flat heat transfer tube. A length of the second passage is equal to or shorter than a length of the first passage. The joint is provided, inside thereof, with a hollow portion.