Air conditioner for a vehicle in which low pressure protection is accurately performed to improve reliability. A controller adjusts a number of revolution Nc of a compressor 2 so that a detected value does not decrease below a limiting target value TGTs, on the basis of the detected value of a suction temperature sensor and a limiting target value TGTs set to a suction refrigerant temperature of the compressor 2. The controller has a predetermined limiting lower limit TGTsL and a predetermined limiting upper limit TGTsH which is higher than the predetermined limiting lower limit, and adjusts the number of revolution Nc of compressor 2 so that the limiting target value TGTs is the limiting upper limit TGTsH on startup of compressor 2, and the controller gradually decreases the limiting target value TGTs toward the limiting lower limit TGTsL, when the detected value decreases to the limiting upper limit TGTsH.

A method for controlling suction pressure in a vapour compression system (1) comprising one or more cooling entities (5) is disclosed. For each cooling entity (5), a maximum required suction pressure and/or a required change in suction pressure for maintaining a target temperature in the refrigerated volume is obtained. A most loaded cooling entity (5) among the one or more cooling entities (5) is identified, based on the maximum required suction pressures and/or the required changes in suction pressure. The suction pressure of the vapour compression system (1) is controlled in accordance with the maximum required suction pressure and/or required change in suction pressure for the identified most loaded cooling entity (5).

A heat pump system for conditioning regeneration air from a space is provided. The heat pump system is operable in a winter mode and/or a summer mode, and may be selectively operated in a defrost mode or cycle. During a defrost mode, hot refrigerant may be used to directly and sequentially defrost the regeneration air heat exchanger. A compressor may be configured to be overdriven during a defrost cycle.

A device and process for refuelling containers with pressurized gas comprising a pressurized gas source, a transfer circuit intended to be removably connected to a container, the device comprising a refrigeration system for cooling the gas flowing from the gas source prior to its entering into the container and comprising a refrigerant cooling loop circuit comprising, arranged in series, a compressor, a condenser section, an expansion valve and an evaporator section, the refrigeration system comprising a cold source in heat exchange with the condenser section and a heat exchanger located in the transfer circuit and comprising a heat exchange section between the gas flowing in the transfer circuit and the evaporator section, the device comprising an electronic controller configured to switch the refrigeration system in first standby mode when the device is not refuelling a container wherein the compressor is switched off when the temperature of the heat exchanger is equal or below a predefined first standby temperature threshold and for started and operated for producing cooling power and cooling the heat exchanger when the sensed temperature of the heat exchanger is above a second standby threshold temperature.

A device for refuelling containers with pressurized gas, comprising a pressurized gas source, a transfer circuit intended to be removably connected to a container, the device comprising a refrigeration system for cooling the gas flowing from the gas source prior to its entering into the container, the refrigeration system comprising a refrigerant cooling loop circuit comprising, arranged in series, a compressor, a condenser section, an expansion valve and an evaporator section, the refrigeration system comprising a cold source in heat exchange with the condenser section and a heat exchanger located in the transfer circuit, the device comprising an electronic controller connected to the expansion valve and configured for controlling cooling power produced by the refrigeration system via the control of the opening of the expansion valve, the device comprising a differential temperature sensor system measuring the difference between the temperature of the refrigerant in the refrigerant cooling loop circuit at the outlet of the heat exchanger and the temperature of the refrigerant in the cooling loop circuit at the inlet of the heat exchanger, the electronic controller being configured for controlling the cooling power produced as a function of this temperature differential.

In order to improve a refrigerant compressor comprising a drive motor and a compressor unit which compresses a refrigerant entering through a suction inlet and allows it to exit through a pressure outlet in such a way that it works as reliably as possible, it is proposed that the refrigerant compressor comprise a compressor monitoring system which is integrated into a compressor control system and which determines a compressor condition by means of a first condition value that corresponds to a first saturation temperature in the suction inlet and a second condition value that corresponds to a second saturation temperature in the pressure outlet, and which compares the compressor condition with permissible compressor conditions lying in a given deployment field of a deployment diagram and initiates a process of switching-off the refrigerant compressor if the compressor condition departs from the deployment field.

A refrigeration system includes a compressor configured to compress a refrigerant, a condenser, and an evaporator. A heat exchanger is disposed downstream of the condenser and upstream of the evaporator, and disposed downstream of the evaporator and upstream of the compressor, the heat exchanger configured to facilitate heat exchange between the refrigerant supplied from the condenser and the refrigerant supplied from the evaporator. A first expansion device is disposed downstream of the heat exchanger and upstream of the evaporator, and a second expansion device is disposed downstream of the condenser and upstream of the heat exchanger. The second expansion device is configured to cool the refrigerant passing therethrough to cool the refrigerant in the heat exchanger supplied from the evaporator to the compressor.

A method for controlling a vapour compression system (1) including a compressor unit (2) including one or more compressors (3, 12), a heat rejecting heat exchanger (4), a receiver (6), an expansion device (7) and an evaporator (8) arranged in a refrigerant path. A pressure value indicating a pressure prevailing inside the receiver (6) is obtained, and the obtained pressure value is compared to a first threshold pressure value. In the case that the obtained pressure value is below the first threshold pressure value, the compressor(s) (3, 12) of the compressor unit (2) are controlled in order to reduce a suction pressure of the vapour compression system (1).

In a method for operating a compressor (22) having an inlet (26) and an outlet (28), the method includes: running the compressor to compress a fluid; shutting down (422) the compressor; determining (420) a condition-dependent threshold restart pressure difference (threshold) across the compressor; relieving the pressure-difference to reach the threshold; and, after the threshold is reached, restarting (434) the compressor.

A method of managing a compressor start operation, the method comprising controlling a valve disposed upstream of a compressor to lower a saturated suction temperature of a refrigerant to be below an ambient temperature while starting the compressor.