Abstract: An ejector refrigeration circuit, which is configured for circulating a refrigerant, includes at least two controllable ejectors, which are connected in parallel and respectively comprise a primary high pressure input port, a secondary low pressure input port and an output port; and a control unit, which is configured for operating the ejector refrigeration circuit employing a method which includes a) operating a first ejector by controlling the opening of its high pressure port until the maximum efficiency of said first ejector has been reached or the actual refrigeration demands are met; b) operating at least one additional ejector by opening its primary high pressure input port for increasing the refrigeration capacity of the ejector refrigeration circuit in case the actual refrigeration demands are not met by operating the first ejector alone.

Abstract: A refrigerating system according to the invention includes a refrigerant circuit having at least one compressor, a condenser/gascooler, an intermediate pressure container, at least one evaporator and a respective expansion device before said at least one evaporator, and refrigerant pipes connecting said elements and circulating a refrigerant therethrough; a high pressure regulating device between the condenser/gascooler and the intermediate pressure container, expanding the refrigerant from a high pressure level to an intermediate pressure level; an intermediate pressure sensor sensing the intermediate pressure level; and a control unit controlling the high pressure regulating device. The control unit in operation limits the maximum refrigerant flow through the high pressure regulating device to a maximum flow value FMax, if the sensed intermediate pressure level exceeds a predetermined threshold value PIntTh.

Abstract: An ejector refrigeration circuit (1), which is configured for circulating a refrigerant, in particular carbon dioxide, comprises at least two controllable ejectors (6, 7), which are connected in parallel and respectively comprise a primary high pressure input port (6a, 7a), a secondary low pressure input port (6b, 7b) and an output port (6c, 7c); and a control unit (28), which is configured for operating the ejector refrigeration circuit (1) employing a method which comprises the steps of: a) operating a first ejector (6) of the at least two controllable ejectors (6, 7) by controlling the opening of its high pressure port (6a) until the maximum efficiency of said first ejector (6) has been reached or the actual refrigeration demands are met; b) operating at least one additional ejector (7) of the at least two controllable ejectors (6, 7) by opening its primary high pressure input port (7a) for increasing the refrigeration capacity of the ejector refrigeration circuit (1) in case the actual refrigeration deman

Abstract: A set of piston compressors (2, 4, 6, 8) for use in a refrigeration system comprises a fluid connection (10) between the crank cases of the piston compressors (2, 4, 6, 8) for allowing oil compensation between said piston compressors (2, 4, 6, 8); and a control unit (12) which in operation monitors the running time of each piston compressor (2, 4, 6, 8) and, in case all piston compressors (2, 4, 6, 8) are running, subsequently interrupts the operation of a respective piston compressor (2, 4, 6, 8) for a predetermined period of time for oil compensation if its running time reaches a predetermined maximum running time.

Abstract: A refrigerating system according to the invention comprises a refrigerant circuit (2) having at least one compressor (4), a condenser/gascooler (6), an intermediate pressure container (8), at least one evaporator (10) and a respective expansion device (12) before said at least one evaporator (10), and refrigerant pipes (14) connecting said elements and circulating a refrigerant therethrough; a high pressure regulating device (16) between the condenser/gas-cooler (6) and the intermediate pressure container (8), expanding the refrigerant from a high pressure level to an intermediate pressure level; an intermediate pressure sensor sensing the intermediate pressure level; and a control unit (18) controlling the high pressure regulating device (16). The control unit (18) in operation limits the maximum refrigerant flow through the high pressure regulating device (16) to a maximum flow value FMax, if the sensed intermediate pressure level exceeds a predetermined threshold value PIntTh.

Abstract: A set of piston compressors (2, 4, 6, 8) for use in a refrigeration system comprises a fluid connection (10) between the crank cases of the piston compressors (2, 4, 6, 8) for allowing oil compensation between said piston compressors (2, 4, 6, 8); and a control unit (12) which in operation monitors the running time of each piston compressor (2, 4, 6, 8) and, in case all piston compressors (2, 4, 6, 8) are running, subsequently interrupts the operation of a respective piston compressor (2, 4, 6, 8) for a predetermined period of time for oil compensation if its running time reaches a predetermined maximum running time.