Systems and methods are provided for detecting low refrigerant charge in a refrigeration system. Specifically, the present invention provides systems and methods for comparing refrigerant charges of the refrigeration system during at least substantial shut down.

A compressor is provided and includes a shell, a compression mechanism, a motor, a data module, and a compressor controller. The data module includes a data module processor and a data module memory. The compressor controller includes a controller processor and a controller memory distinct from the data module processor and the data module memory. The data module receives sensed data, stores the sensed data in the data module memory, determines a first diagnosis of the compressor based on the sensed data, and communicates the sensed data and the first diagnosis to the compressor controller. The compressor controller determines a second diagnosis of the compressor based on the sensed data and verifies the first diagnosis by comparing the first diagnosis to the second diagnosis.

Methods and systems for detecting and recovering from control instability caused by impeller stall in a chiller system are provided. In one embodiment, an impeller stall detection and recovery component of a chiller control unit calculates a control error signal frequency spectrum for an evaporator leaving water temperature, determines whether a high frequency signal content of the control error signal frequency spectrum exceeds acceptable limits, and adjusts a surge boundary control curve downward by a predetermined incremental value in order to resolve instability caused by impeller stall.

Provided is a first unit including a first unit including a compressor and a first heat exchanger; a plurality of second units each including a second heat exchanger and each being connected to the first unit via a plurality of branched pipes; a plurality of valves configured to open to permit refrigerant flows and close to not permit the refrigerant flows; a storage unit configured to store connection information indicating a relationship of connection between the plurality of second units and the plurality of pipes; a closed path pipe that is any of the plurality of branched pipes to which no second unit is connected, and a control unit configured to detect whether the closed path pipe is included in the connection information.

Provided is a first unit including a first unit including a compressor and a first heat exchanger; a plurality of second units each including a second heat exchanger and each being connected to the first unit via a plurality of branched pipes; a plurality of valves configured to open to permit refrigerant flows and close to not permit the refrigerant flows; a storage unit configured to store connection information indicating a relationship of connection between the plurality of second units and the plurality of pipes; a closed path pipe that is any of the plurality of branched pipes to which no second unit is connected, and a control unit configured to detect whether the closed path pipe is included in the connection information.

A transportation refrigeration system and a CAN ID allocation method for a transportation refrigeration system. The transportation refrigeration system includes: a refrigeration circuit including a compressor, a condenser, and a plurality of evaporators connected in parallel, all of which are connected to form a loop; a plurality of chambers, each of the evaporators being located in one of the chambers to adjust the chamber; a plurality of sensors of the same type, each of the sensors being installed in one of the chambers respectively; and a control unit, after being installed in place and energized, the plurality of sensors send their own identification codes to the control unit, and the control unit allocates a CAN ID to each of the sensors after receiving the identification codes of the sensors, so that the identification code of each sensor is bound to the corresponding CAN ID respectively.

A control device for an air conditioning system is provided with: an outdoor-unit control part capable of communication with an outdoor unit (B) through a communication medium, the outdoor-unit control part acquiring, through the communication medium, information about machinery installed in the outdoor unit (B) and outputting control commands to the machinery installed in the outdoor unit (B); and an indoor-unit control part capable of communication with an indoor unit (A) through a communication medium, the indoor-unit control part acquiring, through the communication medium, information about machinery installed in the indoor unit (A) and outputting control commands to the machinery installed in the indoor unit (A). The control device individually changes the operating point of the machinery installed in the indoor unit (A) or the outdoor unit (B), acquires a predetermined state quantity before and after the change, and executes a malfunction prediction operation to determine the presence or absence of an anomaly in the machinery. The control device for the air conditioning system can thereby ascertain the operating state of the air conditioning system more simply and accurately.

An indoor unit includes an air-sending fan, an air inlet through which air of an indoor space is sucked in, and an air outlet located above the air inlet and through which the air sucked in through the air inlet is blown out to the indoor space. A control unit activates the air-sending fan when leakage of the refrigerant is detected. When M [kg] represents an amount of charge of the refrigerant in a refrigeration cycle, LFL [kg/m.sup.3] represents a lower flammable limit of the refrigerant, A [m.sup.2] represents a floor area of the indoor space, and Ho [m] represents a height of the air outlet above a floor surface of the indoor space, the amount of charge M, the lower flammable limit LFL, the floor area A, and the height Ho satisfy a relationship of M<LFL×A×Ho.

A cooling apparatus that cools a cooling target object in a state in which an electromagnetic field or an electric field acts on the cooling target object is provided. The cooling apparatus includes a refrigeration machine to cool a cooling target object, an electromagnetic wave irradiation device to generate an electromagnetic field which acts on the cooling target object, a controller to control operations of the refrigeration machine and the electromagnetic wave irradiation device and perform a subcooling operation of cooling the cooling target object by using the refrigeration machine in a state in which the electromagnetic field is generated, and a temperature sensor to measure a temperature of the cooling target object. In the subcooling operation, the controller controls the intensity of the electromagnetic field generated by the electromagnetic wave irradiation device in accordance with the temperature measured by the temperature sensor.

A cooling apparatus that cools a cooling target object in a state in which an electromagnetic field or an electric field acts on the cooling target object is provided. The cooling apparatus includes a refrigeration machine to cool a cooling target object, an electromagnetic wave irradiation device to generate an electromagnetic field which acts on the cooling target object, a controller to control operations of the refrigeration machine and the electromagnetic wave irradiation device and perform a subcooling operation of cooling the cooling target object by using the refrigeration machine in a state in which the electromagnetic field is generated, and a temperature sensor to measure a temperature of the cooling target object. In the subcooling operation, the controller controls the intensity of the electromagnetic field generated by the electromagnetic wave irradiation device in accordance with the temperature measured by the temperature sensor.