Patent Description:
In general, contemporary air condition systems are supplied a pressure at cruise that is approximately <NUM> psig to <NUM> psig (approximately <NUM> bar to <NUM> bar). The trend in the aerospace industry today is towards systems with higher efficiency. One approach to improve airplane efficiency is to eliminate the bleed air entirely and use electrical power to compress outside air. A second approach is to use lower engine pressure. The third approach is to use the energy in the bleed air to compress outside air and bring it into the cabin. Unfortunately, each of these approaches provides limited efficiency with respect to engine fuel burn.

<CIT> proposes a system comprising an air conditioning unit using an electric motor coupled to the rotary shaft of an air cycle machine (ACM) so that the rotation of the shaft of the ACM is accelerated during phases of flight in which the aircraft engine speed is low, this being when a pressure and flow rate of the air entering the air conditioning unit is below a predetermined threshold. Through this mechanism, the compressor can increase the compression ratio of the air handled by the ACM when the pressure or flow rate of the incoming air is not high enough to supply the air conditioning unit.

<CIT>, which was published after the priority date of the present application therefore cannot be taken into account when considering inventive step, relates to a driven turbocompressor of an air conditioning system, comprising a compressor which is connected to an air intake duct and to an inlet of a cabin of a vehicle, and is configured to receive air from the air intake duct, to compress it and to provide it to the cabin, a motor that is configured to drive the compressor and is surrounded by a casing, a recovery turbine that is configured to expand the cabin air coming from an outlet of the cabin. The device is characterized in that it comprises a cooling duct configured to receive at least part of the expanded air so as to cool the casing of the motor and the motor.

According to an embodiment, an environmental control system includes a compression device including a compressor, a turbine, and an electric motor operably coupled by a shaft. The electric motor and the turbine are arranged in series relative to a flow of a first medium. The turbine is arranged downstream from the electric motor relative to the flow of the first medium.

Optionally, the flow of the first medium is configured to remove heat from one or more electronics of the electric motor.

Optionally, the environmental control system is operable in a plurality of modes including a first mode and a second mode, and a first portion of the flow of the first medium is provided to the electric motor and the turbine in series in both the first mode and the second mode.

Optionally, in the first mode, a second portion of the flow of the first medium is configured to bypass the compression device.

Optionally, in the first mode, the flow of the first medium is driven by a fan.

Optionally, the flow of the first medium is driven by a pressure of the first medium.

Optionally, in the first mode, the compressor is driven by the electric motor.

Optionally, in the second mode, the compressor is driven by the electric motor and the turbine.

Optionally, the environmental control system is part of an aircraft and the first medium is cabin air.

Embodiments herein provide an environmental control system of an aircraft that uses mediums from different sources to power the environmental control system and to provide cabin pressurization and cooling at a high fuel burn efficiency. The medium can generally be air, while other examples include gases, liquids, fluidized solids, or slurries.

With reference now to the FIGS. , various schematic diagrams of a portion of an environment control system (ECS) <NUM>, such as an air conditioning unit or pack for example, is depicted according to non-limiting embodiments. Although the environmental control system <NUM> is described with reference to an aircraft, alternative applications, such as other types of vehicles for example, are also within the scope of the disclosure.

As shown in the FIGS. , the ECS <NUM> is configured to receive a first medium A1 at a first inlet <NUM>. In embodiments where the ECS <NUM> is used in an aircraft application, the first inlet <NUM> is configured to receive a supply of air from a volume <NUM>, such as from a passenger compartment of the vehicle. When the environmental control system is on a plane, the passenger compartment may be a cabin for example. In such embodiments, the first medium A1 may be cabin discharge air, which is air leaving the volume <NUM> and that would typically be discharged overboard. In some embodiments, the ECS <NUM> is configured to extract work from the first medium A1. In this manner, the pressurized air A1 of the volume <NUM> can be utilized by the ECS <NUM> to achieve certain operations.

In an embodiment, the first medium A1 provided at the inlet <NUM> has been used to cool at least one electronic component of the aircraft, illustrated schematically at <NUM>. As shown, the electronic components <NUM> may be considered separate or not part of the ECS <NUM>, and therefore are located upstream from the ECS <NUM> relative to the flow of the first medium A1. Examples of the electronic components <NUM> include, but are not limited to, a high voltage direct current power system, a ram fan motor controller, a compressor motor drive, and a transformer rectified unit. For example, a portion of the cabin discharge air A1, such as about <NUM>% thereof for example, may be directed by a fan or other movement mechanism <NUM> across one or more electronic components <NUM> to remove heat therefrom <NUM> prior to being supplied to the ECS <NUM>. The fan <NUM> may be selectively operable to drive the flow of the first medium A1 through the ECS <NUM>.

The ECS <NUM> is also configured to receive a second medium A2 at an second inlet <NUM> and during normal operation is configured to provide a conditioned form of only the second medium A2 to the volume <NUM>. In an embodiment, the second medium A2 is fresh air, such as outside air for example. The outside air can be procured via one or more scooping mechanisms, such as an impact scoop or a flush scoop for example. Thus, the inlet <NUM> can be considered a fresh or outside air inlet. In an embodiment, the second medium A2 is ram air drawn from a portion of a ram air circuit to be described in more detail below. Generally, the second medium A2 described herein is at an ambient pressure equal to an air pressure outside of the aircraft when the aircraft is on the ground and is between an ambient pressure and a cabin pressure when the aircraft is in flight.

The ECS <NUM> includes a RAM air circuit <NUM> including a shell or duct <NUM> within which one or more heat exchangers are located. The shell <NUM> can receive and direct a medium, such as ram air for example, through a portion of the ECS <NUM>. The one or more heat exchangers are devices built for efficient heat transfer from one medium to another. Examples of the type of heat exchangers that may be used, include, but are not limited to, double pipe, shell and tube, plate, plate and shell, adiabatic shell, plate fin, pillow plate, and fluid heat exchangers.

The one or more heat exchangers arranged within the shell <NUM> may be referred to as ram heat exchangers. In the illustrated, non-limiting embodiment, the ram heat exchangers include a first or primary heat exchanger <NUM> and a second or secondary heat exchanger <NUM>. Within the heat exchangers, a flow of air, such as ram or outside air for example, acts as a heat sink to cool a medium passing there through, for example the second medium A2. The secondary heat exchanger <NUM> may be located upstream from the primary heat exchanger <NUM> such that the temperature of the air provided to the primary heat exchanger <NUM> is higher (warmer) than the temperature of the air provided to the secondary heat exchanger <NUM>. It should be understood that a ram air circuit <NUM> having any number and configuration of heat exchangers is contemplated herein.

The ECS <NUM> additionally includes at least one compression device. The at least one compression device is a mechanical device that includes components for performing thermodynamic work on a medium (e.g., extracts work from or applies work to the first medium A1, the second medium A2 by raising and/or lowering pressure and by raising and/or lowering temperature). Examples of a compression device include an air cycle machine, a two-wheel air cycle machine, a three-wheel air cycle machine, a four-wheel air cycle machine, etc..

In an embodiment, the ECS <NUM> includes a separate and distinct first compression device 40a and second compression device 40b. At least one component of each of the first and second compression device 40a, 40b are arranged in series relative to a flow of the second medium A2. Each compression device 40a, 40b includes a compressor 42a, 42b and at least one turbine 44a, 44b operably coupled by a shaft 46a, 46b. A compressor 42a, 42b 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 44a, 44b is also a mechanical device and is configured to expand a medium and extract work therefrom (also referred to as extracting energy) to drive the compressor via the shaft. In the illustrated, non-limiting embodiment, the second compression device 40b includes a first turbine 44b and a second turbine <NUM>, the second turbine <NUM> also being mounted to the shaft 46b and configured to drive the compressor 42b.

A fan <NUM> is a mechanical device that can force via push or pull methods air through the shell <NUM> of the ram air circuit <NUM>, across at least a portion of the ram air heat exchangers. In an embodiment, best shown in <FIG>, <FIG>, <FIG>, and <FIG>, the fan <NUM> is part (mounted to the shaft) of one of the compression devices of the ECS <NUM>, such as the second compression device 40b for example. However, in other embodiments, best shown in <FIG>, <FIG>, <FIG>, and <FIG>, the fan <NUM> may be separate from the compression devices and driven by any suitable mechanism, such as an electric motor for example.

In an embodiment, the first compression device 40a additionally includes a motor <NUM>. The motor <NUM> is a mechanical/electrical device that can also drive the compressor 42a via the shaft 46a. The motor <NUM> may provide assistance, as needed, to drive the compressor 42a. In an embodiment, as will be described in more detail below, the first medium A1 may also be used to cool or remove heat from the motor <NUM>.

The ECS <NUM> may additionally include at least one dehumidification system. The dehumidification system may be arranged in fluid communication with the second medium A2. In the illustrated, non-limiting embodiments shown in <FIG>, <FIG>, <FIG> and <FIG>, the dehumidification system includes a water extractor or collector <NUM>. The water extractor <NUM> is a mechanical device that performs a process of removing water from a medium. As shown, the water extractor <NUM> is arranged directly downstream from an outlet of a turbine, such as turbine 44b of the second compression device 40b for example. In such embodiments, the turbine 44b is configured to function as a condenser because the temperature of the medium A2 within the turbine 44b is reduced as work is extracted therefrom. The turbine 44b and the water extractor <NUM> in combination may be referred to herein as a "midpressure water separator.

However, in other embodiments, such as shown in <FIG>, <FIG>, <FIG>, and <FIG>, the dehumidification system includes at least a condenser <NUM> and a water extractor <NUM>, the water extractor <NUM> being arranged downstream from the condenser <NUM>. The condenser <NUM> is a particular type of heat exchanger. Further, in an embodiment, the dehumidification system additionally includes a reheater <NUM>.

The elements of the ECS <NUM> are connected via valves, tubes, pipes, 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 ECS <NUM> can be regulated to a desired value. For instance, a first valve V1 is configured to allow all or at least a portion of the first medium A1 to bypass all or a portion of the first compression device 40a and a second valve V2 is configured to redirect a flow of the second medium from the outlet of the compressor 42a back to an inlet of the compressor 42a. A third valve V3 may be operable to direct all or at least a portion of the flow of second medium within the ECS <NUM> to another ECS pack. Valve V4 is operable to allow the flow of second medium A2 to bypass the first turbine 44b of the second compression device 40b and valve V5 is operable to allow the flow second medium A2, such as the flow of second medium A2 from the primary heat exchanger <NUM> for example, to bypass the remainder of the ECS <NUM>. In an embodiment, the remainder of the ECS <NUM> includes the second compression device 40b and the dehumidification system. A sixth valve V6 may be configured to control a supply of the first medium A1 to the ECS <NUM>.

With reference to embodiments illustrated in <FIG> and <FIG>, the ECS <NUM> is operable in a plurality of modes, selectable based on a flight condition of the aircraft. For example, the ECS <NUM> may be operable in a first, low altitude mode or a second, high altitude mode. The first mode is typically used for ground and low altitude flight conditions, such as ground idle, taxi, take-off, and hold conditions, and the second mode may be used at high altitude cruise, climb, and descent flight conditions.

During operation of the ECS <NUM> in a first, low altitude mode, a flow of the first medium A1 is provided to the ECS <NUM> via inlet <NUM>. More specifically, the fan or movement mechanism <NUM> is operational to deliver the first medium A1, which may have been used to cool one or more electronic components of the aircraft prior to entering the ECS <NUM>. In the first, low altitude mode, valve V1 is open. As shown in the non-limiting embodiment of <FIG> and <FIG>, a bypass conduit including bypass valve V1 is arranged upstream from the first compression device 40a. As a result, only a first portion A1a of the first medium A1 is provided to the first compression device 40a and a second portion A1b of the first medium A1 is configured to bypass the first compression device 40a via the valve V1.

The first portion A1a of the first medium A1 may be configured to make a single pass, or alternatively, a plurality of passes about an exterior of and/or through a housing of the motor <NUM>. Because a temperature of the first medium A1 is cooler than the one or more electronics of the motor <NUM>, heat is transferred from the motor <NUM> and its electronics to the first medium A1. The first portion A1a of the first medium A1 that has been heated by the motor <NUM> is then provided to an outflow heat exchanger <NUM>. However, in other embodiments (see <FIG>), only some of the first portion A1a of the first medium A1 is provided to the motor <NUM>. In such embodiments, part of the first portion A1a is configured to bypass the motor <NUM> and is provided directly to the outflow heat exchanger <NUM>. In such embodiments, the first portion A1a of the first medium A1 that was used to cool the motor <NUM> is rejoined with the remainder of the first portion A1a of the first medium A1 at a location at or upstream from the inlet of the outflow heat exchanger <NUM>.

With continued reference to <FIG> and <FIG>, within the outflow heat exchanger <NUM>, the first portion A1a of the first medium A1 is configured to absorb heat from a second medium A2. The warm first medium A1 output from the outflow heat exchanger <NUM> is then provided to an inlet of the turbine 44a of the first compression device 40a. Because the volume is not pressurized when the aircraft is in the first, low altitude mode, minimal work is extracted from the first portion A1a of the first medium A1 within the turbine 44a. Accordingly, in a first, low altitude mode of operation, the motor <NUM> is relied upon to drive the compressor 42a. The first portion A1a of the first medium A1 output from the turbine 44a is then rejoined with the second portion A1b of the first medium A1 that bypassed the first compression device 40a at a location upstream from the ram air circuit <NUM>.

In another embodiment, best shown in <FIG>, the entirety of the first medium A1 provided to the ECS <NUM> is used to cool the motor <NUM>. However, in other embodiments, as shown in <FIG>, only some of the first medium A1 is provided to the motor <NUM>. As shown, a first portion A1a of the first medium A1 is provided to the motor <NUM> of the first compression device 40a and a second portion A1b of the first medium A1 is configured to bypass the motor <NUM>. In such embodiments, the first portion A1a of the first medium A1 that was used to cool the motor <NUM> is rejoined with the remainder of the first portion A1a of the first medium A1 at or upstream from the inlet of the outflow heat exchanger <NUM>.

In the non-limiting embodiments of <FIG> and <FIG>, the bypass conduit including valve V1 is located either directly upstream from the outflow heat exchanger <NUM> or is located downstream from the outflow heat exchanger <NUM> and upstream from the inlet of the turbine 44a of the first compression device 40a. When the bypass conduit is located upstream from the outflow heat exchanger <NUM>, the rejoined first and second portions (A1a and A1b) of the first medium A1 are configured to bypass both the outflow heat exchanger <NUM> and the turbine 44a. In embodiments where the bypass conduit is located downstream from the outflow heat exchanger <NUM> and upstream form the turbine 44a, the warmed first portion A1a of the first medium A1 rejoined with the second portion A1b of the first medium A1 passes through the outflow heat exchanger <NUM> before bypassing the turbine 44a.

Regardless of the location of the first valve V1, the first medium A1, resulting from the mixing of the first portion A1a and the second portion A1b of the first medium A1, may be used to cool a portion of the second medium A2 within at least one of the ram air heat exchangers. In the illustrated, non-limiting embodiment, both the primary heat exchanger <NUM> and the secondary heat exchanger <NUM> are separated into a respective first portion 36a, 38a and second portion 36b, 38b by a divider <NUM>. In an embodiment, the first medium A1 is delivered to the first portion 36a, 38a of the ram air heat exchangers. From the ram air circuit <NUM>, the first medium A1 may be exhausted overboard.

At the same time that the first medium A1 is provided to the ECS <NUM> via inlet <NUM>, the second medium A2 is provided to the ECS <NUM> via inlet <NUM>. From the inlet <NUM>, the second medium A2 may be provided directly to an inlet of the compressor 42a of the first compression device 40a. The act of compressing the second medium A2, heats the second medium A2 and increases the pressure of the second medium A2. The heated second medium A2 output from the compressor 42a is provided to the outflow heat exchanger <NUM>, where heat is transferred from the second medium A2 to the first medium A1. In an embodiment, a portion of the second medium A2 output from the compressor 42a may be returned directly to the inlet of the compressor 42a via valve V2.

The second medium A2 output from the outflow heat exchanger <NUM> may be provided to an ozone converter <NUM> before being provided to the primary heat exchanger <NUM> of the ram air circuit <NUM>. In embodiments where valve V3 is open, a portion of the second medium A2 output from the outflow heat exchanger <NUM> will be diverted to another air conditioning pack via a crossover duct <NUM>. The other air conditioning pack may have a substantially similar configuration, or alternatively, a different configuration than the pack illustrated by ECS <NUM>.

The flow of second medium A2 provided to the primary heat exchanger <NUM> is configured to flow through the first portion 36a and the second portion 36b of the primary heat exchanger <NUM> in series. Within the first portion 36a of the primary heat exchanger <NUM>, the second medium A2 is cooled by a flow of the first medium A1. Within the second portion 36b of the primary heat exchanger <NUM>, the already cool second medium A2 is further cooled by a flow of ram air driven by the fan <NUM>. From the ram air circuit <NUM>, the second medium A2 is provided to the second compression device 40b. In an embodiment, the second medium A2 is provided from the ram air circuit <NUM> to an inlet of the compressor 42b of the second compression device 40b. Within the compressor 42b, the temperature and the pressure of the second medium A2 increases.

From the compressor 42b, the second medium A2 is returned to the ram air circuit <NUM>. As shown, the second medium A2 is similarly provided to the first portion 38a and the second portion 38b of the secondary heat exchanger <NUM> in series. Within the first portion 38a of the secondary heat exchanger <NUM>, the second medium A2 is cooled by the flow of the first medium A1, and within the second portion 38b, the second medium A2 is cooled by a flow of ram air driven by the fan <NUM>.

From the ram air circuit <NUM>, the second medium A2 is provided to the turbine 44b of the second compression device 40b. Within the turbine 44b, the second medium A2 is expanded and work is extracted therefrom. The work extracted therefrom is used to drive the compressor 42b. From the turbine 44b, the second medium A2 is provided to the water extractor <NUM>, where water is removed from the second medium A2. Accordingly, the second medium A2 output from the water extractor <NUM> contains less water than the second medium A2 provided to the water extractor <NUM>. The drier, second medium A2 is then provided to the second turbine <NUM> where further work is extracted from the second medium A2 and used to drive the compressor 42b. The cooler second medium A2 output from the second turbine <NUM> is provided to one or more loads of the aircraft, such as the cabin <NUM>.

In the second, high altitude mode of operation, the flow path of the first and second mediums A1, A2 is similar to that in the first, low altitude mode of operation. However, in the high altitude mode of operation, the fan <NUM> need not be used to drive the flow of the first medium A1 through the inlet <NUM> and the ECS <NUM>. Rather, the pressurization of the first medium A1 may be sufficient to drive the flow of the first medium A1 through the ECS <NUM>. Further, in the high altitude mode, valve V1 is closed. As a result, the entire flow of the first medium A1 is provided to the outflow heat exchanger <NUM> and the first compression device 40a before being exhausted into the ram air circuit <NUM>, and at least a portion of the first medium A1 is configured to cool the motor <NUM>. Accordingly, in the high altitude mode of operation, both the turbine 44a and the motor <NUM> may be used to drive the compressor 42a.

With respect to the flow of the second medium A2, in the high altitude mode valve V4 is opened. As a result, the flow of the second medium A2 output from the secondary heat exchanger <NUM> is configured to bypass the turbine 44b. In such embodiments, the flow of the second medium A2 is provided from the secondary heat exchanger <NUM> to water extractor <NUM> and then to the second turbine <NUM> of the second compression device 40b. The cool, lower pressure second medium A2 output from the second turbine <NUM> may be delivered to one or more loads of the aircraft, such as the cabin <NUM>.

With reference now to <FIG>, <FIG>, <FIG>, and <FIG>, the embodiments of the ECS <NUM> and the corresponding flow paths are similar to the embodiments of <FIG>, <FIG>, <FIG>, and <FIG>. More specifically, the flow path of the first medium A1 in both a low altitude mode and a high altitude mode is identical to the various possible flow paths described with respect to the embodiments of <FIG>, <FIG>, <FIG>, and <FIG>. In the low altitude mode of operation, a fan <NUM> may be used to drive the flow through the ECS <NUM>. Further, all or a portion of the first medium A1 may be configured to bypass the outflow heat exchanger <NUM> and/or the first compression device 40a. In the high altitude mode of operation, the pressurization of the first medium A1 may be sufficient to move the flow through the ECS <NUM>, and the entire flow of the first medium A1 is provided to the outflow heat exchanger <NUM> and the turbine 44a of the first compression device 40a before being exhausted into the ram air circuit <NUM>. In both the low altitude mode and the high altitude modes, at least a portion, and in some embodiments, the entirety of the first medium A1 is provided to the motor <NUM> of the first compression device 40a to cool the motor <NUM>.

In the low altitude mode of operation of the ECS <NUM> of <FIG>, <FIG>, <FIG>, and <FIG>, the second medium A2 is provided to the ECS <NUM> via inlet <NUM> at the same time that the first medium A1 is flowing through the ECS <NUM>. From the inlet <NUM>, the second medium A2 may be provided directly to an inlet of the compressor 42a of the first compression device 40a. The act of compressing the second medium A2, heats the second medium A2 and increases the pressure of the second medium A2. The heated second medium A2 output from the compressor 42a is provided to the outflow heat exchanger <NUM>, where heat is transferred from the second medium A2 to the first medium A1.

The second medium A2 is compressed within the compressor 42a of the first compression device 40a and is cooled within the outflow heat exchanger <NUM>. The second medium A2 output from the outflow heat exchanger <NUM> may be provided to an ozone converter <NUM> before being provided to the primary heat exchanger <NUM> of the ram air circuit <NUM>. As previously described, the flow of second medium A2 provided to the primary heat exchanger <NUM> is configured to flow through the first portion 36a of the primary heat exchanger <NUM> and the second portion 36b of the primary heat exchanger <NUM> in series. Within the first portion 36a of the primary heat exchanger <NUM>, the second medium A2 is cooled by a flow of the first medium A1. Within the second portion 36b of the primary heat exchanger <NUM>, the already cool second medium A2 is further cooled by a flow of ram air driven by the fan <NUM>. From the ram air circuit <NUM>, the second medium A2 is provided to the second compression device 40b. In an embodiment, the second medium A2 is provided from the ram air circuit <NUM> to an inlet of the compressor 42b of the second compression device 40b. Within the compressor 42b, the temperature and the pressure of the second medium A2 increases.

Unlike the ECS <NUM> of <FIG>, <FIG>, <FIG>, and <FIG>, the second medium A2 output from the secondary heat exchanger <NUM> is provided to the dehumidification system, and more specifically, to the reheater <NUM> and condenser <NUM> in series, in which the second medium A2 is cooled, causing moisture within the cool second medium A2 to condense. Upon exiting the condenser <NUM>, the second medium A2 enters the water extractor <NUM>, where the condensed water or moisture is removed from the second medium A2. From the outlet of the water extractor <NUM>, the drier second medium A2 makes another pass through the reheater <NUM>. It is through this heat transfer relationship that heat from the second medium A2 output from the secondary heat exchanger <NUM> is provided to the second medium A2 output from the water extractor <NUM>.

From the reheater <NUM>, the dry second medium A2 is provided to the turbine 44b, such as through a nozzle. The second medium A2 is expanded across the turbine 44b and work is extracted therefrom. The extracted work drives the compressor 42b used to compress the second medium A2. The dry, second medium A2 is then provided to the second turbine <NUM> where further work is extracted from the second medium A2 and used to drive the compressor 42b. The cooler second medium A2 output from the second turbine <NUM> is provided to one or more loads of the aircraft, such as the cabin <NUM>.

In the high altitude mode of operation of the ECS <NUM> of <FIG>, <FIG>, <FIG>, and <FIG>, the flow of the second medium A2 between the inlet <NUM> and the dehumidification system may be substantially the same as in the low altitude mode of operation. However, in the high altitude mode of operation, valve V4 is open, and therefore the second medium A2 is configured to bypass the turbine 44b. As a result, after the second pass of the second medium A2 through the reheater <NUM>, in which the second medium A2 absorbs heat, the second medium A2 is configured to make a second pass through the condenser <NUM>. During operation in the low altitude mode, no significant heat transfer occurs within the condenser <NUM> because only a single fluid, the flow of the second medium A2 output from the first pass of the reheater <NUM> passes therethrough. In the high altitude mode of operation, however, heat is transferred from the flow of the second medium A2 within the first pass of the condenser <NUM> (to be provided to the water extractor <NUM>) to the flow of the second medium A2 in the second pass of the condenser <NUM>.

From the second pass of the condenser <NUM>, the second medium A2 is provided to an inlet of the second turbine <NUM>, such as via a nozzle. Within the second turbine <NUM>, work is extracted and used to drive the compressor 42b used to compress the second medium A2. The cooler second medium A2 output from the second turbine <NUM> may then be provided to one or more loads of the aircraft, such as the cabin <NUM>.

Claim 1:
An environmental control system (<NUM>) comprising:
a compression device (40a, 40b) including a compressor (42a, 42b), a turbine (44a, 44b), and an electric motor (<NUM>) operably coupled by a shaft (46a, 46b),
characterised in that the electric motor (<NUM>) and the turbine (44a, 44b), are arranged in series relative to a flow of a first medium (A1); and the turbine (44a, 44b), is arranged downstream from the electric motor (<NUM>) relative to the flow of the first medium (A1).