An aircraft air conditioning system comprising an ambient air supply line with a first end connected to an ambient air inlet and a second end connected to a mixing chamber. A first electrically driven ambient air compressor in the ambient air supply line compresses the ambient air flowing therethrough. A first ambient air branch line branches off from the ambient air supply line upstream of the first ambient air compressor and rejoins the supply line downstream of the air compressor. A second ambient air compressor in the first ambient air branch line compresses the ambient air flowing therethrough. A cabin exhaust air line has a first end connected to an air conditioned aircraft area. A cabin exhaust air turbine in the exhaust air line is driven by the exhaust air flowing through the cabin exhaust air line and is coupled to drive the second ambient air compressor.

An apparatus for using nitrogen within a closed loop cryogenic system is described. A cryochamber is provided that has a first nitrogen flow line with an inlet for connection to a nitrogen source and an outlet. At least one cryogenic cooling loop is provided that has a nitrogen inlet and a nitrogen outlet. The nitrogen inlet and outlet are in fluid communication with the first nitrogen flow line. The nitrogen inlet is positioned upstream of the nitrogen outlet. A heat exchanger is provided on the at least one cryogenic cooling loops through which the nitrogen passes. The heat exchanger has a fluid inlet and a fluid outlet. A turbo expander is in fluid communication with the outlet of the first nitrogen flow line and the nitrogen source. The turbo expander re-cools the nitrogen that passes through the first flow line and the at least one cryogenic cooling loop.

An apparatus for using nitrogen within a closed loop cryogenic system is described. A cryochamber is provided that has a first nitrogen flow line with an inlet for connection to a nitrogen source and an outlet. At least one cryogenic cooling loop is provided that has a nitrogen inlet and a nitrogen outlet. The nitrogen inlet and outlet are in fluid communication with the first nitrogen flow line. The nitrogen inlet is positioned upstream of the nitrogen outlet. A heat exchanger is provided on the at least one cryogenic cooling loops through which the nitrogen passes. The heat exchanger has a fluid inlet and a fluid outlet. A turbo expander is in fluid communication with the outlet of the first nitrogen flow line and the nitrogen source. The turbo expander re-cools the nitrogen that passes through the first flow line and the at least one cryogenic cooling loop.

A thermal management system includes at least one vapor compression system (VCS) that is configured to cool portions of the vehicle. The VCS circulates a fluid therethrough to cool the portions of the vehicle through heat exchange. At least one reverse air cycle machine (RACM) couples to VCS through a first heat exchanger. The RACM is configured to receive ram air. The RACM expands the ram air. Heat from the fluid circulating through the VCS is transferred to the expanded ram air through the first heat exchanger.

A thermal management system includes at least one vapor compression system (VCS) that is configured to cool portions of the vehicle. The VCS circulates a fluid therethrough to cool the portions of the vehicle through heat exchange. At least one reverse air cycle machine (RACM) couples to VCS through a first heat exchanger. The RACM is configured to receive ram air. The RACM expands the ram air. Heat from the fluid circulating through the VCS is transferred to the expanded ram air through the first heat exchanger.

An environmental control system of an aircraft includes a plurality of inlets for receiving a plurality of mediums including a first medium and a second medium and an outlet for delivering a conditioned flow of the second medium to one or more loads of the aircraft. A ram air circuit includes a ram air shell having at least one heat exchanger positioned therein. A compressing device is arranged in fluid communication with the ram air circuit and the outlet. The compressing device including a first compressor, a second compressor, and at least one turbine operably coupled via a shaft. The first compressor and the second compressor are arranged in parallel with respect to a flow of the second medium and the first medium is used as a heat sink by another component within the environmental control system.

A compressing device for use in an environmental control system includes at least one turbine configured to provide energy by expanding one or more mediums. The one or more mediums provided at an outlet of the at least one turbine form a heat sink within the environmental control system. A compressor is configured to receive energy from the one or more mediums expanded across the at least one turbine. During a first mode of the compressing device, energy derived from a first medium and a second medium of the one or more mediums is used to compress a second medium at the compressor. During a second mode of the compressing device, energy derived from the first medium, the second medium, and a third medium of the one or more mediums is used to compress the second medium at the compressor.

An air cycle machine for an environmental control system for an aircraft includes at least one turbine configured to receive and extract work from a first medium and a third medium. A compressor is configured to compress a second medium and a shaft mechanically couples the at least one turbine and the compressor. A mixing point is located downstream of at least one turbine. A mixture of the first medium and the third medium generated at the mixing point is provided to another component of the environmental control system.

Disclosed is a low-temperature refrigeration device comprising a working circuit that forms a loop and contains a working fluid, the device further comprising a cooling exchanger for extracting heat from at least one member by exchanging heat with the working fluid, the working circuit forming a cycle comprising, connected in series: a compression mechanism, a cooling mechanism, an expansion mechanism and a heating mechanism, wherein the mechanism for cooling the working fluid and the heating mechanism comprise a common heat exchanger in which the working fluid flows in opposite directions in two separate transit portions of the circuit according to whether it is cooled or heated, the device being designed to ensure equal mass flow rates in the two transit portions in the common heat exchanger, the device also comprising a bypass for bypassing one of the two transit portions, said bypass comprising a bypass valve which, in the open state, changes the mass flow rate in one of the two transit portions.

A cooling system for an aircraft includes a first cooling circuit having a first evaporator and a second evaporator, and a second cooling circuit having a third evaporator and a fourth evaporator. One of the first and second cooling circuits includes a first set of valves arranged to direct refrigerant through a first cooling sub-circuit, a second cooling sub-circuit, or both the first and second cooling sub-circuits based on ambient conditions. Two of the evaporators are installed on a first side of the aircraft, and the other two of the four evaporators are installed on a second side of the aircraft opposite the first side, and the first and second cooling circuits reject heat, via a heat exchanger, from their respective cooling circuit to air passing into an engine of the aircraft.