An air-conditioning apparatus including a compressor incorporating an electric motor; a temperature sensor configured to detect indoor temperature; a drive circuit configured to drive the electric motor; a connection switching device configured to switch connection of stator windings of the electric motor between a first connection state and a second connection state higher in line-to-line voltage than the first connection state; and a controller configured to enter thermo-off when the indoor temperature reaches a target temperature or a correction temperature set based on the target temperature and cause the connection switching device to switch connection, the thermo-off being entered by stopping the compressor via the drive circuit. When a thermo-off count reaches a reference count with the electric motor being in the first connection state, the controller causes the connection switching device to switch connection from the first connection state to the second connection state.

A test chamber and a method for conditioning air in a temperature-insulated test space of a test chamber, which is sealable against an environment and serves for receiving test material, a temperature ranging from −20° C. to +180° C. being produced within the test space by means of a cooling device of a temperature control device of the test chamber, using a cooling circuit with carbon dioxide (CO.sub.2) as a cooling agent, using a heat exchanger in the test space, using a low-pressure compressor and using a high-pressure compressor downstream of the low-pressure compressor, using a gas cooler, using a storage means for the cooling agent and using an expansion valve, the temperature in the test space being controlled and/or regulated by means of a control device of the test chamber. A gaseous and/or liquid cooling agent is dosed in the storage means by means of a high-pressure valve of the cooling circuit downstream of the gas cooler, the storage means being connected to a medium-pressure side of the cooling circuit upstream of the high-pressure compressor and downstream of the low-pressure compressor via a medium-pressure bypass of the cooling circuit, the gaseous cooling agent being dosed in the medium-pressure side from the storage means by means of a medium-pressure valve when the low-pressure compressor is switched off.

An apparatus includes a high side heat exchanger, a flash tank, a first load, a first compressor, an auxiliary cooling system, and a first check valve. The high side heat exchanger removes heat from a refrigerant. The flash tank stores the refrigerant from the high side heat exchanger. The first load uses the refrigerant to remove heat from a space proximate the first load. The first compressor compresses the refrigerant from the first load. The auxiliary cooling system removes heat from the refrigerant stored in the flash tank during a power outage. The first check valve directs the refrigerant between the first load and the first compressor back to the flash tank when the pressure of the refrigerant between the first load and the first compressor exceeds a threshold during the power outage.

A hydronic economizer module is configured for use in a chiller system that has a vapor compression cycle. The hydronic economizer module includes a heat exchanger assembly located within a housing having at least one heat exchanger coil, a fan assembly having at least one fan generally aligned with at least one heat exchanger coil, and at least one valve is movable between a plurality of positions to control a flow of fluid into the heat exchanger assembly. When the at least one valve is in a first position, the economizer module is arranged in parallel with a flat plate heat exchanger. When the at least one valve is in a second position, the economizer module is arranged in series with the flat plate heat exchanger. The flat plate heat exchanger includes at least one fluid port for communicating with a component of the vapor compression cycle.

The invention relates to a refrigeration installation (1), to a method for same, and to a refrigeration installation system for controlling the temperature of air, including at least one compressor (3), at least one expansion element (39), and at least one first (5) and a second (7) heat exchanger, each of which can be operated as a condenser or a gas cooler, wherein at least one of the heat exchangers can be operated as an evaporator or at least one additional heat exchanger is provided which can be operated as an evaporator. A refrigerant line is equipped with a first valve (11) downstream of at least one compressor (3) at or downstream of a branch (9) and upstream of or at the condenser or gas cooler inlet (15) of the first heat exchanger (5), and a second valve (19) is arranged at or downstream of the condenser or gas cooler outlet (17) of the first heat exchanger (5) and upstream of or as an expansion element. The refrigeration installation (1) contains at least one valve controller (13) for the first (11) and second valve (19) with at least one first and second possible valve set-up in order to displace the refrigerant, wherein the first valve (11) is open while the second valve (19) is closed at the same time in the first set-up and vice versa in the second set-up. The valve controller (13) comprises an automatic regulator which sets the first valve switch set-up for at least one heat exchanger (5, 7) which is not being used as a with refrigerant flowing through condenser or gas cooler at the moment when a specified refrigerant quantity is exceeded in the refrigerant circuit through which refrigerant is flowing.

A method for controlling a vapour compression system, the vapour compression system including a compressor unit with one or more compressors. At least one of the compressors is connectable to a gaseous outlet of a receiver, and at least one of the compressors is connectable to an outlet of an evaporator. A parameter of the vapour compression system is measured, an enthalpy of refrigerant leaving the heat rejecting heat exchanger being derivable from the measured parameter. A setpoint value for a pressure inside the receiver is calculated, based on the measured parameter, and the compressor unit is operated in accordance with the calculated setpoint value, and in order to obtain a pressure inside the receiver which is equal to the calculated setpoint value. The vapour compression system is operated in an energy efficient manner over a wide range of ambient temperatures.

A compressor frequency regulation method includes acquiring a first exhaust temperature of a compressor operating at a first operating frequency; determining that the first exhaust temperature is greater than or equal to a first preset temperature; controlling the compressor to perform frequency reduction processing, the frequency reduction processing reducing the first operating frequency to a second operating frequency, such that a second exhaust temperature of the compressor operating at the second operating frequency is less than the first preset temperature; and controlling the compressor to operate at the second operating frequency.

A heat pump arrangement includes a heat pump device, an evaporator cycle interface for inputting liquid to be cooled into the heat pump device and for outputting cooled liquid out of the heat pump device, a condenser cycle interface for inputting liquid to be heated into the heat pump device and for outputting heated liquid out of the heat pump device, a controllable heat exchanger for controllably coupling the evaporator cycle interface and the condenser cycle interface, and a control for controlling the controllable heat exchanger in dependence on an evaporator cycle temperature in the evaporator cycle interface or a condenser cycle temperature in the condenser cycle interface.

A rotary compressor system includes a compressor housing that includes a compressor motor that draws in fluid from a suction side. The fluid is compressed within a compression chamber and discharged through a discharge side. The compression chamber is disposed between the suction side and the discharge side. An overload-protection switch is electrically coupled in series with the compressor motor and is adapted to cut power to the compressor motor responsive to an overload event. A solenoid valve is fluidly coupled between the compression chamber and a location upstream of the suction side and is electrically coupled in series with the overload-protection switch. An interruption of electrical current to the compressor motor also interrupts electrical current to the solenoid valve, which opens the solenoid valve to equalize pressure between the suction side and the discharge side.

The present invention relates to a low-power absorption refrigeration machine that enables the use of air as a refrigerant and has an evaporation unit that is separated from the rest of the absorption refrigeration machine and works with LiBr/H.sub.2O, H.sub.2O/NH.sub.3, LiNO.sub.3/NH.sub.3 or similar solutions, configuring an air-air machine wherein cold is produced directly in the enclosure to be air conditioned without need for impeller pumps and fan coils.