Abstract: A refrigerant vapor compression system includes a flash tank economizer and a refrigerant-to-refrigerant heat exchanger economizer disposed in series refrigerant flow relationship in the refrigerant circuit intermediate a refrigerant heat rejection heat exchanger and a refrigerant heat absorption heat exchanger. A primary expansion valve disposed in the refrigerant circuit in operative association with and upstream of the refrigerant heat absorption heat exchanger and an economizer expansion valve disposed in the refrigerant circuit in operative association and upstream of the flash tank economizer provide a two-step expansion process for expanding refrigerant passing through the refrigerant circuit from the refrigerant heat rejection heat exchanger to the refrigerant heat absorption heat exchanger.

Abstract: The transcritical refrigeration system is provided with a main compressor and booster compressor that is made to operate in parallel with the main compressor only during pulldown conditions. A single, two stage compressor is provided with valving which is controlled so as to provide for the two stages operating in series in normal operation and for operating in parallel during pulldown conditions.

Abstract: A carbon dioxide refrigerant vapor compression system and method of operating that system are provided. The refrigerant vapor compression system includes a compression device, a flash tank receiver disposed in the refrigerant circuit intermediate a refrigerant heat rejection heat exchanger and a refrigerant heat absorption heat exchanger, and a compressor unload circuit including a refrigerant line establishing refrigerant flow communication between an intermediate pressure stage of the compression device and the refrigerant circuit at a location downstream of the refrigerant heat absorption heat exchanger and upstream of a suction inlet to the compression device, and a unload circuit flow control device disposed in said unload circuit refrigerant line. In response to at least one system operating parameter sensed by at least one sensor, the controller selectively positions the unload flow control device to maintain the refrigerant vapor compression system operating below a preselected high pressure limit.

Abstract: A refrigerant vapor compression system includes a flash tank receiver disposed in the refrigerant circuit intermediate the refrigerant cooling heat exchanger and the refrigerant heating heat exchanger. The flash tank receiver, which receives a liquid/vapor refrigerant mix, also functions as a receiver. A refrigerant charge control apparatus includes at least one sensor for sensing an operating characteristic of the refrigerant circulating through the refrigerant compression device, and a controller operative to selectively adjust a secondary expansion device to increase or decrease the flow of refrigerant passing into the flash tank receiver to provide a circulating refrigerant charge consistent with maintaining a desired system operating characteristic.

Abstract: A refrigerant vapor compression system includes a flash tank receiver disposed in the refrigerant circuit intermediate the refrigerant cooling heat exchanger and the refrigerant heating heat exchanger. The flash tank receiver, which receives a liquid/vapor refrigerant mix, also functions as a receiver. A refrigerant charge control apparatus includes a liquid level sensing device disposed in operative association with the flash tank receiver for sensing the level of liquid refrigerant within the flash tank receiver, at least one sensor for sensing a system operating parameter, and a controller operative to determine a desired liquid refrigerant level within the flash tank receiver and to selectively adjust a secondary expansion device to increase or decrease the flow of refrigerant passing into the flash tank receiver to provide a circulating refrigerant charge consistent with maintaining a desired system operating parameter.

Abstract: A refrigerant vapor compression system includes a flash tank disposed in series refrigerant flow relationship in the refrigerant circuit intermediate a refrigerant heat rejection heat exchanger and a refrigerant heat absorption heat exchanger. A primary expansion valve is interdisposed in the refrigerant circuit upstream of the refrigerant heat absorption heat exchanger and a secondary expansion valve is interdisposed in the refrigerant circuit upstream of the flash tank. A refrigerant vapor line is provided to direct refrigerant vapor from the flash tank to an intermediate pressure stage of the compression process. A refrigerant-to-refrigerant heat exchanger operates to transfer heat from refrigerant flowing through the primary refrigerant circuit to refrigerant flowing through the refrigerant vapor line.

Abstract: A refrigeration system (20A) comprises an evaporator (27), a two-stage compressor (32) for compressing a refrigerant, a second compressor (34) for compressing the refrigerant, a heat rejecting heat exchanger (24) for cooling the refrigerant, a first economizer circuit (25A), and a second economizer circuit (25B). The first economizer circuit (25A) is configured to inject refrigerant into an interstage port (48) of the two-stage compressor (32). The second economizer circuit (25B) is connected to the second compressor (34).

Abstract: A refrigeration system (20A) comprises an evaporator (27) for evaporating a refrigerant, a two-stage compressor (32) for compressing the refrigerant, a single-stage compressor (34) for compressing the refrigerant, a heat rejecting heat exchanger (24) for cooling the refrigerant, a first economizer circuit (25A), and a second economizer circuit (25B). The first economizer circuit (25A) is configured to inject refrigerant into an interstage port (48) of the two-stage compressor (32). The second economizer circuit (25B) is configured to inject refrigerant into a suction port (52) of the single-stage compressor (34). The single-stage compressor (34) is configured to discharge into the interstage port (48) of the two-stage compressor (32).

Abstract: A refrigerant vapor compression system includes a refrigerant-to-refrigerant heat exchanger economizer and a flash tank disposed in series refrigerant flow relationship in the refrigerant circuit intermediate a refrigerant heat rejection heat exchanger and a refrigerant heat absorption heat exchanger. A primary expansion valve is interdisposed in the refrigerant circuit upstream of the refrigerant heat absorption heat exchanger and a secondary expansion valve is interdisposed in the refrigerant circuit upstream of the flash tank. The flash tank functions as a refrigerant charge storage reservoir wherein refrigerant expanded from a supercritical pressure to subcritical pressure separates into liquid and vapor phases. A refrigerant vapor bypass line is provided to return refrigerant vapor from the flash tank to the refrigerant circuit downstream of the refrigerant heat absorption heat exchanger.

Abstract: A refrigerant vapor compression system includes a flash tank economizer defining a separation chamber is disposed in the refrigerant circuit intermediate a refrigerant heat rejection heat exchanger and a refrigerant heat absorption heat exchanger. A primary expansion valve is interdisposed in the refrigerant circuit in operative association with and upstream of the refrigerant heat absorption heat exchanger and a secondary expansion valve is interdisposed in the refrigerant circuit in operative association and upstream of the flash tank economizer. A refrigerant vapor injection line establishes refrigerant flow communication between an upper portion of the separation chamber and an intermediate pressure stage of the system's compression device and a suction pressure portion of the refrigerant circuit.

Abstract: A refrigeration system includes a compressor, first and second heat exchangers, and an expansion device. A refrigerant recirculating flowpath extends sequentially downstream through the compressor, first heat exchanger, expansion device, and second heat exchanger The system includes a charge storage system. The charge storage system includes first and second refrigerant storage chambers. At least one valve is coupled to the storage chambers to permit the storage chambers to each be individually placed in alternative communication with the flowpath upstream and downstream of the expansion device.

Abstract: A method for controlling temperature pulldown of an enclosure with a refrigeration system having a compressor, a heat rejecting heat exchanger, an expansion valve, and an evaporator comprises circulating a refrigerant through the refrigeration system, sensing a parameter of the enclosure, determining a desired evaporator pressure based upon the parameter sensed, and adjusting the expansion valve as a function of the desired evaporator pressure.

Abstract: A multi-stage compressor unit for a refrigeration system configured to circulate a refrigerant comprises a first compressor sub-unit having a first stage and a second stage, and a second compressor sub-unit in parallel with the first compressor sub-unit and having a first stage. The first and second stages of the first compressor sub-unit each have a suction port and a discharge port. The first compressor sub-unit is configured to receive and compress a first portion of the refrigerant from an evaporator. The first stage of the second compressor sub-unit is configured to compress a second portion of the refrigerant.