Methods and systems for controlling a chiller system to achieve control stability while maintaining optimum efficiency. Particularly, methods and systems for controlling a centrifugal compressor speed and an inlet guide vane position that establishes three distinct regions in the control path: (i) during initial unloading from full load, the inlet guide vane position is kept at a fully open position while the centrifugal compressor speed is changed to achieve the desired cooling capacity; (ii) between an inflection point and a transition point, keeping the centrifugal compressor speed constant while the inlet guide vane position is changed to achieve the desired cooling capacity; and (iii) between the transition point and zero cooling capacity, changing both the inlet guide vane position and the centrifugal compressor speed to achieve the desired cooling capacity.

A packaged, pumped liquid, recirculating refrigeration system with charges of 10 lbs or less of refrigerant per ton of refrigeration capacity. The compressor and related components are situated in a pre-packaged modular machine room, and in which the condenser is mounted on the machine room and the evaporator is close coupled to the pre-packaged modular machine room. Prior art large receiver vessels may be replaced with a single or dual phase cyclonic separator also housed in the pre-packaged modular machine room.

A climate-control system may include a compressor and a control module. The compressor includes a motor driving a compression mechanism to compress a working fluid. The control module is in communication with the motor and may be configured to determine a balance speed of the motor at which a forward-rotational inertial force of the compression mechanism is equal to a backward-rotational gas force on the compression mechanism. The control module may be configured to adjust a running speed of the motor to the balance speed after receipt of a compressor-shutdown-command and before shutting down the compressor.

A system includes a plurality of compressors, an evaporator, an expansion device, and a system controller. The compressors may be linked in parallel. The system controller may: determine a saturated evaporator temperature, a saturated condensing temperature, and a target capacity demand; determine an estimated system capacity and an estimated power consumption for each compressor operating configuration; compare the estimated system capacity with the target capacity demand and an error tolerance value; select an optimum operating mode based on the comparisons and based on the estimated power consumption; and command activation and deactivation of the plurality of compressors to achieve the selected optimum operating mode. The optimum operating mode may be selected after the normal system logic achieves a steady state and may be selected from a group having the estimated system capacity within the error tolerance of the target capacity demand and a lowest associated power consumption value.

A set temperature calculating apparatus, a low temperature treatment system, a set temperature calculating method, and a set temperature calculating program are provided for realizing a low temperature treatment. The set temperature calculating apparatus includes: a first obtaining unit configured to obtain data correlating with a heat load in a container storage; a second obtaining unit configured to obtain a set temperature when performing temperature control in the container storage; and a learning unit configured to learn a cargo core temperature in the container storage according to a data set including a combination of the data correlating with the heat load and the set temperature.

A refrigeration cycle device includes a refrigerant circuit switching device. The refrigerant circuit switching device is configured to switch among at least a first circuit and a second circuit. The first circuit conducts refrigerant, which is outputted from a heat releasing device, to a liquid storage and conducts the refrigerant, which is outputted from the liquid storage, to a first depressurizing device and conducts the refrigerant, which is depressurized by the first depressurizing device, to an external heat exchanger. The second circuit conducts the refrigerant, which is outputted from the external heat exchanger, to the liquid storage and conducts the refrigerant, which is outputted from the liquid storage, to a second depressurizing device and conducts the refrigerant, which is depressurized by the second depressurizing device, to an evaporating device.

Refrigeration systems and control methods therefor are described. The refrigeration systems include a main circuit to connect, through a pipeline, a multi-stage compressor, a condenser, an economizer, a main throttling element, and an evaporator. An air supply branch is configured to connect to the air outlet of the economizer and the intermediate stage air inlet of the multi-stage compressor. A liquid injection branch is configured to connect to the intermediate stage air inlet of the multi-stage compressor from a section having a high-pressure liquid-phase refrigerant in the main circuit. Through the design of the liquid injection branch, the liquid-phase refrigerant can be introduced when vibration or noise of the unit exceeds a limit. The liquid-phase refrigerant, in the form of droplets, can effectively absorb the sound wave energy in the compressor pipeline to reduce an overall discharge pulsation of the compressor and reduce the noise and vibration of the condenser.

A method of controlling an air conditioner including activating a refrigeration cycle by driving an compressor; detecting a high pressure and a low pressure when the refrigeration cycle is activated; adjusting an operating frequency of the compressor based on the detected high pressure or low pressure of the refrigeration cycle; determining a current load of an inside space through a load detecting unit; determining a load level of the inside space by comparing the current load with a reference load; and determining the operating frequency of the compressor based on the determined load level.

A method and a correspondingly designed device are provided for controlling or regulating a coolant circuit of an air conditioning system, which includes at least one compressor, at least one condenser or gas cooler, and at least one evaporator. A controllable coolant expansion device is connected to the coolant inlet of the evaporator. It is detected when the coolant circuit is under filled with a coolant and, when an under filling of the coolant is detected, the control strategy of the expansion device is changed.

A method for controlling a vapour compression system (1) is disclosed, the vapour compression system (1) comprising an ejector (5). The method comprises controlling a compressor unit (2) in order to adjust a pressure inside a receiver (6), on the basis of a detected pressure of refrigerant leaving an evaporator (8). The portion of refrigerant leaving the evaporator (8) which is supplied to a secondary inlet (15) of the ejector is maximised and the portion of refrigerant supplied directly to the compressor unit (2) is minimised, while ensuring that the pressure of refrigerant leaving the evaporator (8) does not decrease below an acceptable level.