Abstract: A system and method for a CO2 refrigeration system includes a compressor, a heat exchanger, a liquid receiver, a first valve, and a valve controller. The heat exchanger operates as a gas cooler when the CO2 refrigeration system is in a transcritical mode and as a condenser when the CO2 refrigeration system is in the subcritical mode. The first valve controls a flow of refrigerant from the heat exchanger to the liquid receiver. The valve controller monitors an outdoor ambient temperature and a pressure of refrigerant exiting the heat exchanger, determines whether the CO2 refrigeration system is in the subcritical mode or in the transcritical mode, determines a pressure setpoint based on the monitored outdoor ambient temperature, and controls the first valve based on a comparison of the determined pressure setpoint and the monitored pressure when the CO2 refrigeration system is in the transcritical mode.

Abstract: A system and method for a CO2 refrigeration system includes a compressor, a heat exchanger, a liquid receiver, a first valve, and a valve controller. The heat exchanger operates as a gas cooler when the CO2 refrigeration system is in a transcritical mode and as a condenser when the CO2 refrigeration system is in the subcritical mode. The first valve controls a flow of refrigerant from the heat exchanger to the liquid receiver. The valve controller monitors an outdoor ambient temperature and a pressure of refrigerant exiting the heat exchanger, determines whether the CO2 refrigeration system is in the subcritical mode or in the transcritical mode, determines a pressure setpoint based on the monitored outdoor ambient temperature, and controls the first valve based on a comparison of the determined pressure setpoint and the monitored pressure when the CO2 refrigeration system is in the transcritical mode.

Abstract: The present invention refers to a linear compressor comprising a piston (9) arranged slidably inside a cylinder (15); in said cylinder (15) the 15 piston (9) defines a first low-pressure chamber (21) and a second high-pressure chamber (22), said piston being further provided with communication means (23) between said first and said second chamber (21, 22), which are controlled by valve means (24) to establish such communication therebetween.