EP4428002A1

EP4428002A1 - Hyperloop environmental control system

Info

Publication number: EP4428002A1
Application number: EP24160494.1A
Authority: EP
Inventors: Richard Rusich; Louis J. Bruno
Original assignee: Hamilton Sundstrand Corp
Current assignee: Hamilton Sundstrand Corp
Priority date: 2023-03-09
Filing date: 2024-02-29
Publication date: 2024-09-11
Also published as: US20240300547A1

Abstract

An environmental control system for conditioning a cabin of a vehicle positioned in an enclosed air-evacuated environment includes a first inlet (24) for receiving a first medium (A1); a second inlet (26) for receiving a second medium, a first thermodynamic device (30) and a second thermodynamic device (32). The first thermodynamic device (30) is fluidly coupled to both the first inlet (24) and the second inlet (26) and the second thermodynamic device (32) is fluidly coupled to the second inlet (26). The second medium is provided to the first thermodynamic device (30) and the second thermodynamic device (32) in parallel.

Description

BACKGROUND

The present disclosure relates to an environmental control system of a vehicle, and more particularly, to an environmental control system (ECS) for a vehicle travelling in a low pressure or zero pressure environment.
In general, a high-speed public transportation concept called the hyperloop has been proposed that can include a vehicle similar to a train car that travels inside of a tube. The air in the tube can be evacuated to a very deep vacuum, allowing the train to reach very high speeds without incurring the high-power demand that would otherwise be needed to overcome the high aerodynamic drag at normal atmospheric pressure. An air lock can permit passenger boarding and disembarking from the train station to the train without discharging the atmospheric air in the station into the vacuum in the tube.
As with similar transportation vehicles, environmental control of the occupied cabin is generally required to maintain adequate comfort and to provide heating, cooling and/or a continual supply of fresh air. Some typical methods used to provide air conditioning may not be conducive to this application. For example, many air conditioning systems exist which provide cool air to the cabin and on-board electronics may draw air from or ultimately exhaust the heat to the ambient atmosphere via convection heat transfer. When the ambient atmosphere is non-existent, as in space applications, heat can be rejected to deep space via radiation heat transfer. In the case of the hyperloop, there is little to no atmosphere in the tube, so rejecting heat into the tube via convection may not be practical while maintaining a reasonably sized heat exchanger to reject the heat. Moreover, heat rejection via radiation may also not be practical, since unlike radiating to space, which is near absolute zero degrees in temperature, the walls of the tube can be warmer than inside the cabin when the outside ambient temperature is warm. Moreover, while the train is moving at high speed, the amount of available electrical power consumption is limited since power is generally supplied solely by on-board batteries that have a limited quantity of electrical energy.

BRIEF DESCRIPTION

According to an embodiment an environmental control system for conditioning a cabin of a vehicle positioned in an enclosed air-evacuated environment includes a first inlet for receiving a first medium; a second inlet for receiving a second medium, a first thermodynamic device and a second thermodynamic device. The first thermodynamic device is fluidly coupled to both the first inlet and the second inlet and the second thermodynamic device is fluidly coupled to the second inlet. The second medium is provided to the first thermodynamic device and the second thermodynamic device in parallel.
In addition to one or more of the features described above, or as an alternative, in further embodiments the second thermodynamic device is a turbogenerator.
In addition to one or more of the features described above, or as an alternative, in further embodiments the first thermodynamic device includes a compressor and at least one turbine operably coupled by a shaft.
In addition to one or more of the features described above, or as an alternative, in further embodiments the at least one turbine is a dual entry turbine.
In addition to one or more of the features described above, or as an alternative, in further embodiments the at least one turbine includes a first turbine and a second turbine operably coupled by the shaft.
In addition to one or more of the features described above, or as an alternative, in further embodiments the compressor and the at least one turbine are arranged in series relative to the flow of the second medium.
In addition to one or more of the features described above, or as an alternative, in further embodiments a heat exchanger is fluidly coupled to both the compressor and the at least one turbine. The heat exchanger is positioned downstream from the compressor and upstream from the at least one turbine relative to the flow of the second medium.
In addition to one or more of the features described above, or as an alternative, in further embodiments the flow of the second medium output from the compressor is cooled within the heat exchanger by the flow of the second medium output from the second thermodynamic device.
In addition to one or more of the features described above, or as an alternative, in further embodiments a flow of the first medium and a flow of the second medium are mixed at a mixing point located downstream from an outlet of the at least one turbine.
In addition to one or more of the features described above, or as an alternative, in further embodiments a bypass conduit extends between and fluidly couples the second inlet to the mixing point such that a portion of the second medium provided at the second inlet is configured to bypass both the first thermodynamic device and the second thermodynamic device.
In addition to one or more of the features described above, or as an alternative, in further embodiments a circulation fan is operably coupled to the bypass conduit and is operable to pump the portion of the second medium through the bypass conduit and move air within the cabin.
In addition to one or more of the features described above, or as an alternative, in further embodiments including at least one vessel of a pressurized first medium located on board the vehicle.
In addition to one or more of the features described above, or as an alternative, in further embodiments the vehicle is a train.
According to an embodiment, a method of operating an environmental control system to condition a cabin of a vehicle positioned in an enclosed, air-evacuated tube includes extracting energy from a first medium at at least one turbine of a first thermodynamic device, pumping a first portion of a second medium to bypass the first thermodynamic device and a second thermodynamic device, mixing a second portion of the second medium with a flow of medium output from a cooling system to form a third medium, providing a first portion of the third medium to the second thermodynamic device and providing a second portion of the third medium to the first thermodynamic device, and mixing the first medium, the first portion of the second medium, and the second portion of the third medium at a mixing point to form a conditioned medium.
In addition to one or more of the features described above, or as an alternative, in further embodiments providing the first portion of the third medium to the second thermodynamic device includes extracting energy from the first portion of the third medium.
In addition to one or more of the features described above, or as an alternative, in further embodiments providing the second portion of the third medium to the first thermodynamic device includes compressing a second portion of the third medium at a compressor of the first thermodynamic device, providing the second portion of the third medium from the compressor to the at least one turbine of the first thermodynamic device, and extracting energy from the second portion of the third medium.
In addition to one or more of the features described above, or as an alternative, in further embodiments cooling the second portion of the third medium output from the compressor using the first portion of the third medium output from the second thermodynamic device via a heat exchanger. The heat exchanger is arranged upstream from the at least one turbine.
In addition to one or more of the features described above, or as an alternative, in further embodiments removing moisture from the conditioned medium.
In addition to one or more of the features described above, or as an alternative, in further embodiments providing a first portion of the conditioned medium to the cabin and providing a second portion of the conditioned medium to the cooling system.
In addition to one or more of the features described above, or as an alternative, in further embodiments providing the second portion of the conditioned medium to the cooling system includes removing heat from the cooling system.

BRIEF DESCRIPTION OF THE DRAWINGS

The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:
The Figure (Figure 1) is a schematic diagram of an example environmental control system (ECS) for a vehicle travelling within a hyperloop tube according to an embodiment.

DETAILED DESCRIPTION

A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.
The example embodiments disclosed herein are illustrative of a hyperloop environmental control system, and assemblies of the present disclosure and methods/techniques thereof. It should be understood, however, that the disclosed embodiments are merely examples of the present disclosure, which may be embodied in various forms. Therefore, details disclosed herein with reference to example hyperloop environmental control systems and associated processes/techniques of fabrication/assembly and use are not to be interpreted as limiting, but merely as the basis for teaching one skilled in the art how to make and use the systems/assemblies and/or alternative systems/assemblies of the present disclosure.
With reference now to the Figure, an example of an environmental control system 20 suitable for use with a vehicle movable within an enclosed air-evacuated environment is illustrated. The air-evacuated environment has a substantially zero-pressure or is a vacuum. In an embodiment, the vehicle is a car or train movable through a tube of a hyperloop system. As shown, the environmental control system 20 includes one or more vessels 22 located on-board the vehicle and configured to store a pressurized medium therein, such as high-pressure air for example. In an embodiment, the pressure of the medium within the at least one vessel 22 is between about 2000psi about 3000psi. The one or more vessels 22 may be considered a first fluid source and are fluidly coupled to a first inlet 24 of the environmental control system 20 to deliver a controlled flow of a first medium A1 to the environmental control system 20. The one or more vessels 22 may be filled, refilled, or replaced when the vehicle is stopped at a station or other facility.
The environmental control system 20 may additionally receive a second medium A2 at a second inlet 26. In one embodiment, the second inlet 26 is operably coupled to a volume 28, such as the cabin or chamber of the vehicle in which the people are typically located. In such embodiments, the second medium A2 is cabin recirculation air. The environmental control system 20 is operable to provide a conditioned flow of one or both of the first medium A1 and the second medium A2 to the cabin 28 at standard atmospheric pressure of about 14.7 psi.
The environmental control system 20 may include at least one thermodynamic device, and in some embodiments, includes a plurality of thermodynamic devices. A thermodynamic device, as described herein, is a mechanical device that includes one or more components for performing thermodynamic work on a medium (e.g., extracts work from or applies work to the first medium A1 or the second medium A2 by raising and/or lowering pressure and by raising and/or lowering temperature). Examples of a thermodynamic device include an air cycle machine, a two-wheel air cycle machine, a three-wheel air cycle machine, a four-wheel air cycle machine, and a turbogenerator etc.
In the illustrated, non-limiting embodiment, the environmental control system 20 includes a first thermodynamic device 30 and a second thermodynamic 32. The first and second thermodynamic device 30, 32 may, but need not be arranged in series relative to a flow of at least one of the first medium A1 and the second medium A2 during at least one mode of operation of the environmental control system 20.
The first thermodynamic device 30 includes a compressor 34 and at least one turbine operably coupled by a shaft 36. In the illustrated, non-limiting embodiment, the first thermodynamic device includes 30 a first turbine 38 and a second turbine 40. Although the first turbine 36 and the second turbine 38 are illustrated and described herein as two distinct turbines separately mounted to the shaft 34, it should be appreciated that a single turbine having two distinct inlets and nozzles for receiving two separate fluid flows may alternatively be used. For example, a single turbine, sometimes referred to as a dual entry turbine may have a first nozzle and inlet associated with the operations described herein relative the first turbine 38 and a second nozzle and inlet associated with the operations described herein relative to the second turbine 40. However, embodiments where the first thermodynamic device 30 includes a single turbine, or alternatively, more than two turbines are also within the scope of the disclosure.
A compressor, such as compressor 34 for example, is a mechanical device configured to raise a pressure of a medium and can be driven by another mechanical device (e.g., a motor or a medium via a turbine). Examples of compressor types include centrifugal, diagonal or mixed-flow, axial-flow, reciprocating, ionic liquid piston, rotary screw, rotary vane, scroll, diaphragm, air bubble, etc. A turbine, such as first turbine 38 or second turbine 40 for example, is a mechanical device that expands a medium and extracts work therefrom (also referred to as extracting energy) to drive the compressor via the shaft. The turbine may include a nozzle (not shown) configured to accelerate the medium supplied thereto for entry into an impeller of the turbine.
In an embodiment, the second thermodynamic device 32 is a simple cycle or two-wheel machine, such as a turbogenerator. As shown, the second thermodynamic device 32 includes a turbine 42 that directly drives an electric generator 44 via a shaft 46. Although the turbine 42 and the electric generator 44 are illustrated as being connected directly to the same shaft 46, it should be understood that embodiments where the generator 44 is indirectly connected to the turbine 42, such as where the generator 44 includes a separate shaft connected to the shaft 46 via a coupler for example, are also within the scope of the disclosure. In operation, rotation of the turbine 42 extracts energy from the medium provided thereto and converts it into electrical energy via the generator 44. The energy created at the generator 44 may be stored, such as within a battery (not shown) and/or may be sent to at least one electrical load of the vehicle.
In addition to providing a conditioned medium to the chamber 28, the environmental control system 20 may be used to transfer or redistribute heat between various systems onboard the vehicle. In an embodiment, the environmental control system 20 is operably coupled to a cooling system 50 used to cool high-powered electronics 52 located onboard the vehicle. As shown, a coolant, such as propylene glycol or ethylene glycol for example, is configured to circulate through the electronics 52 via a coolant pump 54, then is then provided to an electronics heat exchanger 56. In the illustrated, non-limiting embodiment, the environmental control system 20 is operably coupled to the cooling system 50 via the electronics heat exchanger 56. Accordingly, at the electronics heat exchanger 56, during operation of the environmental control system 20 in a "cooling mode" where the air provided to the cabin 28 is intended to reduce the temperature therein, heat is transferred from the coolant to the relatively cool medium of the environmental control system 20. Heat may also be transferred from the coolant to the relatively cool medium of the environmental control system 20 during operation in a "heating mode" where the air provided to the cabin is intended to increase the temperature therein.
The elements of the environmental control system 20 are connected via valves, tubes, pipes, conduits and the like. Valves (e.g., flow regulation device or mass flow valve) are devices that regulate, direct, and/or control a flow of a medium by opening, closing, or partially obstructing various passageways within the tubes, pipes, etc. of the system. Valves can be operated by actuators, such that flow rates of the medium in any portion of the environmental control system 20 can be regulated to a desired value. For instance, a first valve V1, such as an airflow regulator for example, is configured to control the flow of the first medium A1 provided to the environmental control system 20 via the first inlet 24. A second valve V2 may be operable to control the flow of a conditioned medium to both the cabin and to the cooling system 50 and a third valve V3 may be operable to allow a portion of a medium to bypass a portion of the first thermodynamic device 30, such as the first turbine 38 for example. The environmental control system 20 may additionally include one or more valves V4, V5 operable to exhaust a flow of medium from the cabin 28 or the environmental control system 20 overboard from the vehicle, such as into the atmosphere surrounding the exterior of the vehicle.
One or more of the valves V1-V5 may be configured to receive commands from an ECS controller (not shown), such as in response to feedback provided from one or more sensors S located in specific/desired locations in the system 20. Although various pressure and temperature sensors are illustrated, it should be appreciated that other sensors operable to monitor any suitable parameter of the environmental control system 20 and/or the cooling system 50 are within the scope of the disclosure.
Furthermore, a heater 60, such as an electrical heater for example, may also be provided for instances where the medium to be delivered to the cabin 28 needs to be heated. In such embodiments, the heater 60 may be arranged directly upstream from the cabin 28 relative to a flow of the conditioned medium. Alternatively, or in addition, a heater 62, such as an electrical heater, may be provided in the cooling system 50 for instances where the medium to be delivered to the cabin 28 needs additional heat beyond the load exhausted by the electronics 52.
In operation, a flow of the first medium A1 at the first inlet 24, controlled by valve V1, is provided to the environmental control system 20. When the downstream valve V3 is in a first position, all or at least a portion of the flow of the first medium A1 is provided to the thermodynamic device 30, such as to the first turbine 38 for example. However, when the valve V3 is in a second position, some or all of the flow of the first medium A1 is directed to a bypass conduit 64 arranged in parallel with an inlet of the first turbine 36. Within the bypass conduit 64, the first medium A1 is configured to bypass the entire thermodynamic device 30.
Within the first turbine 38, the first medium A1 is expanded and work is extracted therefrom to form an expanded first medium. As a result, the first medium A1 provided at the outlet of first turbine 38 is cooler and/or has a lower pressure than the first medium A1 provided to the inlet of the first turbine 38. The term "expanded first medium" may refer to the first medium A1 from the bypass conduit 64, the expanded first medium A1 output from the first turbine 38, or some mixture thereof.
At the same time, the second medium A2 is provided to the second inlet 26 of the environmental control system 20 from the cabin 28. As shown, in some embodiments, the flow of the second medium A2 may split into a first portion A2a and a second portion A2b. Operation of a circulation fan 64 associated with the cabin 28 is configured not only to move the air within the cabin 28, but also to pump the first portion A2a of the second medium through a bypass conduit 65 toward a mixing point M located downstream from the outlet of the first turbine 38.
The second portion A2b of the second medium is mixed with a flow of medium Ac returned from the cooling system 50, such as output from the electronics heat exchanger 56 for example, to form a mixed medium A3. This mixed flow may then be divided into a first portion and a second portion. The percentage of the flow of the mixed medium provided to each of first portion and the second portion may be substantially equal, or alternatively, may vary. The first portion A3a of this mixed medium is provided to the second thermodynamic device 32. For example, the first portion A3a is provided to the inlet of the turbine 42. Within the turbine 42, the first portion A3a of the mixed medium is expanded and work is extracted therefrom. The work extracted from the first portion A3a of the mixed medium within the turbine 42 is used to drive the generator 44 and therefore generate power. The first portion A3a of the mixed medium provided at the outlet of turbine 42 is cooled and/or has a lower pressure than the first portion A3a of the mixed medium provided to the inlet of the turbine 42.
The first portion A3a of the mixed medium output from the turbine is ultimately exhausted overboard, such as into the vacuum environment surrounding the vehicle. In an embodiment, as shown in the FIG., a heat exchanger 70 is located downstream from the outlet of the turbine 42 of the second thermodynamic device 32. In such embodiments, the first portion A3a of the mixed medium provided to a first inlet of the heat exchanger is 70 is heated within the heat exchanger 70 before being exhausted overboard.
The second portion A3b of the mixed medium is provided to the first thermodynamic device 30. In an embodiment, the second portion A3b of the mixed medium is provided to an inlet of the compressor 34. The work extracted from the first medium A1 in the first turbine 38 is used to drive the compressor 34 to compress the second portion A3b of the mixed medium. The act of compressing the second portion A3b of the mixed medium heats the second portion A3b of the mixed medium and increases the pressure thereof. In some embodiments, the outlet of the compressor is fluidly coupled to a second inlet of the heat exchanger 70. Accordingly, within the heat exchanger 70, the second portion A3 of the mixed medium output from the first thermodynamic device 30, for example the compressor 34, may be cooled by the first portion A3a of the mixed medium output from a portion of the second thermodynamic device 32, such as the turbine 42.
The second outlet of the heat exchanger 70 may be fluidly coupled to an inlet of a turbine of the first thermodynamic device 30, such as the second turbine 40 for example. Accordingly, the second portion A3b of the mixed medium is configured to flow through the compressor 34 and a turbine 40 of the first thermodynamic device 30 in series. Within the second turbine 40, the second portion A3b of the mixed medium is expanded and work is extracted therefrom. The work extracted from the second portion A3b of the mixed medium in the second turbine 40 is used alone or in combination with the work extracted at the first turbine 38 to drive the compressor 34 to compress the second portion A3b of the mixed medium. Accordingly, the second portion A3b of the mixed medium provided at the outlet of second turbine 40 is cooler and/or has a lower pressure than the second portion A3b of the mixed medium provided to the inlet of the second turbine 40.
The cool second portion A3b of the mixed medium output from the second turbine 40 may be mixed with the expanded first medium A1 output from the outlet of the first turbine 38 at a mixing point. In the illustrated, non-limiting embodiment, the mixing point M of the second portion A3b of the mixed medium and the expanded first medium A1 is the same location where the first portion A2a of the second medium is mixed with the expanded first medium A1. For example, the outlet of the first turbine 38, the bypass conduit 65 and the outlet of the second turbine 40 are each fluidly coupled to a mixing unit or duct in which the flows are mixed to form a conditioned medium A4. However, in other embodiments, the mixing point of the second portion A3b of the mixed medium and the expanded first medium A1 may be offset from the mixing point between the first portion A2a of the second medium and the expanded first medium A1. Regardless of the relative location of the mixing points, the first medium A1, the first portion A2a of the second medium, and the second portion A3b of the mixed medium are combined to form a conditioned medium A4. It should be understood that all mixing of the expanded first medium A1, the first portion A2a of the second medium, and the second portion A3b of the mixed medium to form a conditioned medium A4 for delivery to the cabin 28 occurs at a location upstream from valve V2, and in some embodiments, from a water collector 72. By removing any liquid present within the conditioned medium A4, the conditioned medium A4 output from the water collector 72 is dried or dehumidified.
From the water collector 72, all or at least a portion of the dried conditioned medium A4 is provided to the cabin 28 to condition the cabin 28. Depending on the operating conditions of the environmental control system 20, in some embodiments, the dried conditioned medium A4 output from the water collector 72 may be separated into a first conditioned flow A4a used to condition the cabin 28 and a second conditioned flow A4b for use by the cooling system 50. The amount of the conditioned flow A4 provided to the cabin 28 and the cooling system 50, respectively, is determined by the position of the valve V2. In an embodiment, the volume of conditioned air or the rate at which the conditioned air A4a is provided to the cabin 28 is equal to the volume or rate at which air is exhausted from the cabin 28 overboard into the surrounding environment via the cabin pressure regulator V4. As a result, the pressure within the cabin 28 remains generally constant.
As previously described, the second conditioned flow A4b may be provided to an electronics heat exchanger 56 of the cooling system 50. Within the electronics heat exchanger 56, the second conditioned flow A4b typically acts as a heat sink to absorb heat from the coolant. The resulting heated medium output from the electronics heat exchanger 56, represented as flow Ac, is then returned to the environmental control system 20 where it is mixed with the second portion A2b of the second medium upstream from both the first and second thermodynamic devices 30, 32.
An environmental control system 20 as illustrated and described here provides an efficient system for conditioning a cabin 28 of a vehicle travelling within a vacuum.
The term "about" is intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms "a," "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof.
While the present disclosure has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made, and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this present disclosure, but that the present disclosure will include all embodiments falling within the scope of the claims.

Claims

An environmental control system for conditioning a cabin of a vehicle positioned in an enclosed air-evacuated environment, the environmental control system comprising:
a first inlet (24) for receiving a first medium (A1);

a second inlet (26) for receiving a second medium; and

a first thermodynamic device (30) and a second thermodynamic device (32), the first thermodynamic device (30) being fluidly coupled to both the first inlet (24) and the second inlet (26) and the second thermodynamic device (32) being fluidly coupled to the second inlet (26), the second medium being provided to the first thermodynamic device (30) and the second thermodynamic device (32) in parallel.
The environmental control system of claim 1, wherein the second thermodynamic device (32) is a turbogenerator.
The environmental control system of claim 1 or 2, wherein the first thermodynamic device (30) further comprises a compressor (34) and at least one turbine operably coupled by a shaft.
The environmental control system of claim 3, wherein the at least one turbine is a dual entry turbine.
The environmental control system of claim 3, wherein the at least one turbine further comprises a first turbine and a second turbine operably coupled by the shaft.
The environmental control system of claim 3, wherein the compressor (34) and the at least one turbine are arranged in series relative to the flow of the second medium.
The environmental control system of claim 6, further comprising a heat exchanger fluidly coupled to both the compressor (34) and the at least one turbine, the heat exchanger being positioned downstream from the compressor (34) and upstream from the at least one turbine relative to the flow of the second medium, and preferably wherein the flow of the second medium output from the compressor (34) is cooled within the heat exchanger by the flow of the second medium output from the second thermodynamic device (32).
The environmental control system of claim 3, wherein a flow of the first medium (A1) and a flow of the second medium are mixed at a mixing point located downstream from an outlet of the at least one turbine, and preferably further comprising a bypass conduit extending between and fluidly coupling the second inlet (26) to the mixing point such that a portion of the second medium provided at the second inlet (26) is configured to bypass both the first thermodynamic device (30) and the second thermodynamic device (32), and more preferably further comprising a circulation fan operably coupled to the bypass conduit, the circulation fan being configured to pump the portion of the second medium through the bypass conduit and move air within the cabin.
The environmental control system of any preceding claim, further comprising at least one vessel of a pressurized first medium located on board the vehicle.
The environmental control system of any preceding claim, wherein the vehicle is a train.
A method of operating an environmental control system to condition a cabin of a vehicle positioned in an enclosed, air-evacuated tube, the method comprising:
extracting energy from a first medium (A1) at at least one turbine of a first thermodynamic device (30);

pumping a first portion of a second medium to bypass the first thermodynamic device (30) and a second thermodynamic device (32);

mixing a second portion of the second medium with a flow of medium output from a cooling system to form a third medium;

providing a first portion of the third medium to the second thermodynamic device (32) and providing a second portion of the third medium to the first thermodynamic device (30); and

mixing the first medium (A1), the first portion of the second medium, and the second portion of the third medium at a mixing point to form a conditioned medium.
The method of claim 11, wherein providing the first portion of the third medium to the second thermodynamic device (32) further comprises extracting energy from the first portion of the third medium.
The method of claim 11 or 12, wherein providing the second portion of the third medium to the first thermodynamic device (30) further comprises:
compressing a second portion of the third medium at a compressor (34) of the first thermodynamic device (30);

providing the second portion of the third medium from the compressor (34) to the at least one turbine of the first thermodynamic device (30); and

extracting energy from the second portion of the third medium, and preferably further comprising cooling the second portion of the third medium output from the compressor (34) using the first portion of the third medium output from the second thermodynamic device (32) via a heat exchanger, the heat exchanger being arranged upstream from the at least one turbine.
The method of any of claims 11-13, further comprising removing moisture from the conditioned medium.
The method of any of claims 11-14, further comprising:
providing a first portion of the conditioned medium to the cabin; and

providing a second portion of the conditioned medium to the cooling system, and preferably wherein providing the second portion of the conditioned medium to the cooling system further comprises removing heat from the cooling system.