Abstract:
A method for controlling a vapour compression system (1), the vapour compression system (1) comprising a compressor unit (2) comprising one or more compressors (10, 11, 13), is disclosed. At least one of the compressors (11, 13) of the compressor unit (2) is connectable to a gaseous outlet (9) of a receiver (5), and at least one of the compressors (10, 13) of the compressor unit (2) is connectable to an outlet of an evaporator (7). A parameter of the vapour compression system (1) is measured, an enthalpy of refrigerant leaving the heat rejecting heat exchanger (3) being derivable from the measured parameter. A setpoint value for a pressure inside the receiver (5) is calculated, based on the measured parameter, and the compressor unit (2) is operated in accordance with the calculated setpoint value, and in order to obtain a pressure inside the receiver (5) which is equal to the calculated setpoint value. The vapour compression system (1) is operated in an energy efficient manner over a wide range of ambient temperatures.
Abstract:
A method for controlling a vapour compression system (1) is disclosed, the vapour compression system (1) comprising at least one compressor (2, 16), a heat rejecting heat exchanger (3), a high pressure expansion device (4, 15, 17), a receiver (5), an evaporator expansion device (6), an evaporator (7) and a gas bypass valve (8), arranged in a refrigerant path. It is registered that the gas bypass valve (8) is malfunctioning or saturated, and a pressure value for a pressure prevailing inside the receiver (5) is obtained. Finally, the vapour compression system (1) is controlled in order to control a gaseous refrigerant supply to the receiver (5) to adjust the pressure prevailing inside the receiver (5) to reach a target pressure level.
Abstract:
A method for controlling a vapour compression system (1) is disclosed. A mass flow of refrigerant along a part of the refrigerant path is estimated, based on measurements performed by one or more pressure sensors (10, 12, 13) for measuring a refrigerant pressure at selected positions along the refrigerant path and one or more temperature sensors (11, 4) for measuring a refrigerant temperature at selected positions along the refrigerant path. A refrigerant pressure or a refrigerant temperature at a selected position a pressure sensor (10, 12, 13) or temperature sensor (11, 14) along the refrigerant path is derived, based on the estimated mass flow. The vapour compression system (1) is allowed to continue operating, even if a sensor (10, 11, 12, 13, 14) is malfunctioning or unreliable.
Abstract:
A method for controlling a vapour compression system (1) is disclosed. A mass flow of refrigerant along a part of the refrigerant path is estimated, based on measurements performed by one or more pressure sensors (10, 12, 13) for measuring a refrigerant pressure at selected positions along the refrigerant path and one or more temperature sensors (11, 14) for measuring a refrigerant temperature at selected positions along the refrigerant path. A refrigerant pressure or a refrigerant temperature at a selected position a pressure sensor (10, 12, 13) or temperature sensor (11, 14) along the refrigerant path is derived, based on the estimated mass flow. The vapour compression system (1) is allowed to continue operating, even if a sensor (10, 11, 12, 13, 14) is malfunctioning or unreliable.
Abstract:
A method for controlling a vapour compression system (1) is disclosed, the vapour compression system (1) comprising at least one compressor (2, 16), a heat rejecting heat exchanger (3), a high pressure expansion device (4, 15, 17), a receiver (5), an evaporator expansion device (6), an evaporator (7) and a gas bypass valve (8), arranged in a refrigerant path. It is registered that the gas bypass valve (8) is malfunctioning or saturated, and a pressure value for a pressure prevailing inside the receiver (5) is obtained. Finally, the vapour compression system (1) is controlled in order to control a gaseous refrigerant supply to the receiver (5) to adjust the pressure prevailing inside the receiver (5) to reach a target pressure level.
Abstract:
A method for controlling a vapour compression system (1) is disclosed. The vapour compression system (1) comprises an ejector (6) and a liquid separating device (10) arranged in a suction line. A liquid level sensor (18) is arranged in the liquid separating device (10). A liquid level in the liquid separating device (10) is monitored by means of the liquid level sensor (18). In the case that the liquid level in the liquid separating device (10) is above a predefined threshold level, a control parameter of the vapour compression system (1) is adjusted in order to increase a flow rate of refrigerant from the liquid separating device (10) to the secondary inlet (15) of the ejector (6) and/or decrease a flow rate of liquid refrigerant from the evaporator(s) (9) to the liquid separating device (10).
Abstract:
A method for controlling ejector capacity in a vapour compression system (1) is disclosed. A parameter value being representative for a flow rate of liquid refrigerant from the evaporator(s) (8, 10) and into a return pipe (12, 13) is obtained, and the capacity of the ejector(s) (6) is adjusted based on the obtained parameter value. Ejector capacity may be shifted between low pressure ejectors (liquid ejectors) (6a, 6b, 6c, 6d) and high pressure ejectors (gas ejectors) (6e, 6f).
Abstract:
A method for controlling a variable capacity ejector unit (7) arranged in a refrigeration system (1) is disclosed. An ejector control signal for the ejector unit (7) is generated, based on an obtained temperature and an obtained pressure of refrigerant leaving a heat rejecting heat exchanger (3), or on the basis of a high pressure valve control signal for controlling an opening degree of a high pressure valve (6) arranged fluidly in parallel with the ejector unit (7). The ejector control signal indicates whether the capacity of the ejector unit (7) should be increased, decreased or maintained. The capacity of the ejector unit (7) is controlled in accordance with the generated ejector control signal. The power consumption of the refrigeration system (1) is reduced, while the pressure of the refrigerant leaving the heat rejecting heat exchanger (3) is maintained at an acceptable level.
Abstract:
A method for controlling a vapour compression system (1) is disclosed. Malfunctioning of a gas bypass valve (8) is registered. An actual opening degree of the gas bypass valve (8) is derived, and a target opening degree of the gas bypass valve (8) is derived, based on one or more control parameters of the vapour compression system (1). The actual opening degree is compared to the target opening degree, and the vapour compression system (1) is controlled based on the comparison, and in order to match a mass flow of gaseous refrigerant through the gas bypass valve (8) to the actual opening degree of the gas bypass valve (8).