A defrost system includes: a cooling device in a freezer, and includes a casing, a heat exchanger pipe with a difference in elevation in the casing, and a drain receiver unit below the heat exchanger pipe; a refrigerating device to cool and liquefy CO.sub.2 refrigerant; and a refrigerant circuit for permitting the cooled and liquefied CO.sub.2 refrigerant to circulate to the heat exchanger pipe. The defrost system includes a bypass pipe of the heat exchanger pipe to form a CO.sub.2 circulation path; an on-off valve in the heat exchanger pipe to be closed during defrosting so that the CO.sub.2 circulation path is a closed circuit; a pressure adjusting unit for adjusting pressure of the CO.sub.2 refrigerant during defrosting; and a brine circuit as a first heating medium, in which the defrost system permits the CO.sub.2 refrigerant to naturally circulate in the closed circuit during defrosting by a thermosiphon effect.

An air conditioner and a method of controlling the same are provided. The air conditioner includes first and second compressors capable of performing multi-stage compression, a condenser for condensing a refrigerant compressed in the first and second compressors, a refrigerant separation device for separating the refrigerant to be injected to the first or second compressor of the refrigerant condensed in the condenser, injection tubes extending from the refrigerant separation device to the first and second compressors to guide injection of the refrigerant, a main expansion device disposed at an outlet-side of the refrigerant separation device to decompress the refrigerant, an evaporator for evaporating the refrigerant decompressed in the main expansion device, a valve device disposed at an outlet-side of the first compressor to guide the refrigerant compressed in the first compressor to the condenser or the second compressor, and a bypass tube extending from the valve device to an suction-side of the second compressor.

For more efficient operation of an air cooled chiller, a refrigerant pump and bypass valve connected in parallel feed refrigerant from the condenser to a receiver. The pump is activated in response to pressure in the condenser; the bypass is used otherwise. Further efficiency is provided by controlling the condenser fan based on power consumption by the air cooled chiller and/or resetting a set point of the evaporator to meet load conditions. An expansion valve for the evaporator is controlled based on chilled water temperature, such as Delta T, or information from an air handling unit. Feedback of valve setting or position, air temperature, valve size, and/or importance of an air handling unit may be used to control the flow of chilled water. In addition to or an alternative to control of the chilled water flow, the refrigerant temperature may be controlled based on information from the air handling unit.

The cooling apparatus includes: a compressor configured to generate compressed air; first and second vortex tubes configured to generate cold air based on the compressed air generated from the compressor; a first valve installed between the compressor and the first vortex tube; a second valve installed between the compressor and the second vortex tube; first and second temperature sensors installed in the power converter and configured to measure the internal temperature of the power converter; and a control unit configured to determine whether or not the first and second vortex tubes supply the cold air into the power converter, based on first and second temperatures respectively measured by the first and second temperature sensors, and to transmit a valve open signal or a valve close signal to the first and second valves based on a result of the determination.

An air conditioner is provided. The air conditioner includes a heat pump cycle channel in which a compressor, an outdoor heat exchanger, an expansion valve, and an indoor heat exchanger are connected with one another in sequence. A resistance channel is disposed between an outlet of the compressor and the outdoor heat exchanger to increase pressure of refrigerant flowing from the outlet to the outdoor heat exchanger.

A refrigeration cycle device includes an air heat exchanger that heats air to be blown into an interior of a vehicle compartment using refrigerant discharged from a compressor, a high-stage side expansion valve decompressing the refrigerant flowing out of the air heat exchanger, and a battery heat exchanger that heats air to be blown to a battery using the refrigerant decompressed by the high-stage side expansion valve. In an air heating-warming up mode of heating the air for the interior and the air for the battery, a refrigerant discharge capacity of the compressor is controlled such that an air temperature for the interior approaches a target air temperature, and an opening degree of the high-stage side expansion valve is controlled such that a battery temperature becomes within a predetermined reference temperature range. A selector switch allows a passenger to select which operation of air conditioning or warming-up is prioritized.

The present subject matter provides a damper valve. The damper valve includes an outer sleeve and an inner sleeve. The inner sleeve is positioned within the outer sleeve and is pivotable between a first position and a second position within the outer sleeve. Radial openings of the inner sleeve align with radial openings of the outer sleeve when the inner sleeve is in the first position, and axial openings of the inner sleeve align with axial openings of the outer sleeve when the inner sleeve is in the second position. A related heat pump water heater appliance is also provided.

An HVAC system, including a reversing valve including a first port, a second port, and a third port, wherein the reversing valve may be placed into a first position in which the first port is operably coupled to the second port for the flow of refrigerant therebetween, and a second position in which the second port is operably coupled to the third port for the flow of refrigerant therebetween, a first HVAC component operably coupled to the first port, a second HVAC component operably coupled to the second port, and a third HVAC component operably coupled to the third port.

A refrigeration system with pressure balancing function includes a condensing unit, a first refrigerant delivery pipeline, and a pressure balance control device including a temperature control unit, a first refrigerant control valve and a refrigerant supply switching controller. The temperature control unit determines if the temperature of the evaporator is abnormal, generates a temperature adjustment trigger signal that shifts between adjustment level and non-adjustment level. The refrigerant supply switching controller will determine, based on the level of the temperature adjustment trigger signal, whether to output the valve-open signal to the first refrigerant control valve. When the temperature adjustment trigger signal received by the refrigerant supply switching controller is at the adjustment level, the refrigerant supply switching controller will not output the valve-open signal to the first refrigerant control valve, so that the first refrigerant control valve is closed to stop delivering the refrigerant to the first refrigerant delivery pipeline.

A hybrid air handler cooling unit has a bi-modal heat exchanger. In a direct expansion mode or a pumped refrigerant economization mode, the bi-modal heat exchanger is in a refrigerant path in parallel with first and second condenser coils and functions as a condenser coil. In a mixed direct expansion/pumped refrigerant economization mode, the bi-modal heat exchanger is in a refrigerant path in series between an outlet of a pump and an inlet of the first condenser coil and functions as a pre-cooler evaporator coil with return air first flowing across the bi-modal heat exchanger and then across an evaporator coil of an evaporator.