Danfoss A/s

Frede Schmidt

Jan Prins

Kenneth Bank Madsen

Kristian Fredslund

Kenn So Jensen

Leif Skovvang Nielsen

Flemming Morten Schmidt

Roozbeh Izadi-Zamanabadi

Christian Bendtsen

Torben Green

Jans Prins

Kenneth Bang Madsen

A method for controlling a vapour compression system () is disclosed. Malfunctioning of a gas bypass valve () is registered. An actual opening degree of the gas bypass valve () is derived, and a target opening degree of the gas bypass valve () is derived, based on one or more control parameters of the vapour compression system (). The actual opening degree is compared to the target opening degree, and the vapour compression system () is controlled based on the comparison, and in order to match a mass flow of gaseous refrigerant through the gas bypass valve () to the actual opening degree of the gas bypass valve ().

Method for controlling a vapour compression system during gas bypass valve malfunction

A method for controlling a vapour compression system () is disclosed, the vapour compression system () comprising at least one expansion device () and at least one evaporator (). For each expansion device (), an opening degree of the expansion device () is obtained, and a representative opening degree, OD, is identified based on the obtained opening degree(s) of the expansion device(s) (). The representative opening degree could be a maximum opening degree, OD, being the largest among the obtained opening degrees. The representative opening degree, OD, is compared to a predefined target opening degree, OD, and a minimum setpoint value, SP, for a pressure prevailing inside a receiver (), is calculated or adjusted, based on the comparison. The vapour compression system () is controlled to obtain a pressure inside the receiver () which is equal to or higher than the calculated or adjusted minimum setpoint value, SP.

Method for controlling a vapour compression system with a variable receiver pressure setpoint

A method for controlling a vapour compression system () 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 () for measuring a refrigerant pressure at selected positions along the refrigerant path and one or more temperature sensors () 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 () or temperature sensor () along the refrigerant path is derived, based on the estimated mass flow. The vapour compression system () is allowed to continue operating, even if a sensor () is malfunctioning or unreliable.

Method for handling fault mitigation in a vapour compression system

A method for operating a compressor unit () comprising one or more compressors () is disclosed, the compressor unit () being arranged in a vapour compression system (). Two or more options for distributing the available compressor capacity of the compressor unit () between being connected to a high pressure suction line () and to a medium pressure suction line () are defined. For each option, an expected impact on one or more operating parameters of the vapour compression system (), resulting from distributing the available compressor capacity according to the option, is predicted. An option is selected, based on the predicted expected impact for the options, and based on current operating demands of the vapour compression system (), and the available compressor capacity is distributed according to the selected option, e.g. by means of settings of one or more valve arrangements ().

Method for switching compressor capacity

A method for controlling a vapour compression system () is disclosed, the vapour compression system () comprising at least one compressor (), a heat rejecting heat exchanger (), a high pressure expansion device (), a receiver (), an evaporator expansion device (), an evaporator () and a gas bypass valve (), arranged in a refrigerant path. It is registered that the gas bypass valve () is malfunctioning or saturated, and a pressure value for a pressure prevailing inside the receiver () is obtained. Finally, the vapour compression system () is controlled in order to control a gaseous refrigerant supply to the receiver () to adjust the pressure prevailing inside the receiver () to reach a target pressure level.

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.

Method for operating a vapour compression system with a receiver

A method for operating a vapour compression system () comprising a heat recovery heat exchanger () is disclosed. The heat recovery system requests a required level of recovered heat to be provided by the heat recovery heat exchanger () to the heat recovery system, generates a signal indicating the required level of recovered heat, and supplies the generated signal to a control unit of the vapour compression system (). A setpoint value for at least one control parameter of the vapour compression system () is calculated, based on the generated signal, and the vapour compression system () is operated in accordance with the calculated setpoint value(s).

Method for operating a vapour compression system with heat recovery

A method for controlling a vapour compression system in an energy efficient and stable manner, the vapour compression system () including at least two evaporator groups (), each evaporator group () including an ejector unit (), at least one evaporator () and a flow control device () controlling a flow of refrigerant to the at least one evaporator (). For each evaporator group () the outlet of the evaporator () is connected to a secondary inlet () of the corresponding ejector unit ().

Vapour compression system with at least two evaporator groups

A method for controlling a vapour compression system having an ejector includes, in the case that a pressure difference between a pressure prevailing in the receiver and a pressure of refrigerant leaving the evaporator decreases below a first lower threshold value, the pressure of refrigerant leaving the heat rejecting heat exchanger is kept at a level which is slightly higher than the pressure level providing optimal coefficient of performance.

Method for controlling a vapour compression system in ejector mode for a prolonged time

A method for controlling a fan () of a vapour compression system () is disclosed, the fan () being arranged to provide a secondary fluid flow across a heat rejecting heat exchanger (). A temperature difference, &#x394;T=T&#x2212;T, between a temperature, T, of refrigerant leaving the heat rejecting heat exchanger () and a temperature, T, of ambient air of the heat rejecting heat exchanger () is established. A setpoint value, &#x394;T, for the temperature difference, &#x394;T, is obtained, the setpoint value, &#x394;T, being dependent on the fan speed of the fan () in such a manner that the setpoint value, &#x394;T, increases as the fan speed increases. The fan speed of the fan () is controlled in order to control the temperature difference, &#x394;T, in accordance with the obtained setpoint value, &#x394;T.

Method for controlling a fan of a vapour compression system in accordance with a variable temperature setpoint

A level sensor is configured to provide a receiver level indicating an amount of the refrigerant present in the receiver and a level model provides a heat rejecting heat exchanger estimate indicating an amount of the refrigerant present in the heat rejecting heat exchanger based on a temperature of the refrigerant. From the sensor and the model, a loss of refrigerant from the refrigerant vapor compression system is estimated.

Method and system for estimating loss of refrigerant charge in a refrigerant vapor compression system

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

Method for controlling a vapour compression system with an ejector

A vapour compression system () includes an ejector () and a liquid separating device () arranged in a suction line. At least one evaporator () is allowed to be operated in a flooded state. A flow rate of refrigerant from the liquid separating device () to the secondary inlet () of the ejector () is detected, and it is determined whether or not the flow rate is sufficient to remove liquid refrigerant produced by the evaporator(s) () from the liquid separating device (). In the case that it is determined that the flow rate of refrigerant from the liquid separating device () to the secondary inlet () of the ejector () is insufficient to remove liquid refrigerant produced by the evaporator(s) (), the flow rate of refrigerant from the liquid separating device () to the secondary inlet () of the ejector () is increased, and/or a flow rate of liquid refrigerant from the evaporator(s) () to the liquid separating device () is decreased.

Method for controlling a vapour compression system in a flooded state

A method for controlling a valve arrangement (), e.g. in the form of a three way valve, in a vapor compression system () is disclosed, the vapor compression system () comprising an ejector (). The valve arrangement () is arranged to supply refrigerant to a compressor unit () from the gaseous outlet () of a receiver () and/or from the outlet of an evaporator (). The vapor compression system () may be operated in a first mode of operation (summer mode) or in a second mode of operation (winter mode). When operated in the second mode of operation, it is determined whether or not conditions for operating the vapor compression system () in the first mode of operation are prevailing. If this is the case, the valve arrangement () is actively switched to the first mode of operation by closing a first inlet () towards the evaporator () and fully opening a second inlet () towards the receiver ().

Method for controlling a valve arrangement in a vapour compression system

The invention relates to a method for configuring, on a control unit, operating parameters of a plurality of devices of a refrigeration system. A user selects on the control unit, among the plurality of devices of the refrigeration system, a first device to configure. Information of valid configurable operating parameters of the first device is provided on the control unit. The user selects at least one of the valid configurable operating parameters of the first device, thereby configuring the first device. Information stored about operating parameters of other devices of the refrigeration system, based on the configuration of the first device, is then provided on the control unit. Finally, the user confirms, on the control unit, one or more operating parameters of one or more of the other devices, thereby configuring the one or more other devices. The invention also relates to a control unit and a refrigeration system.

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Sønderborg, Denmark

Frede Schmidt