Patent Description:
Embodiments of the disclosure relate to environmental control systems, and more specifically to an environmental control system of an aircraft.

Aircraft need to have their internal environment controlled. In general, contemporary air conditioning systems are supplied a pressure at cruise that is approximately <NUM> psig to <NUM> psig (<NUM> to <NUM> kPa). The trend in the aerospace industry today is towards smaller systems with higher efficiency. One approach to improve efficiency of an aircraft environmental control system 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 cabin outflow air to compress outside air and bring it into the cabin. Each of these approaches alone provides limited efficiency with respect to engine fuel burn. An ECS is disclosed in <CIT>, in <CIT> and also in <CIT>.

According to one aspect, an environmental control system of a vehicle is provided as defined by claim <NUM>.

In embodiments the expansion device includes a turbo-generator.

In further embodiments comprising a heat exchanger arranged upstream from the expansion device relative to a flow of the second medium, wherein heat is transferred from the first medium to the second medium in the heat exchanger.

In further embodiments, the second medium output from the expansion device is exhausted overboard.

In further embodiments comprising a ram air circuit including a ram air shell having a ram air heat exchanger positioned therein.

In further embodiments the second medium output from the expansion device is provided to the ram air shell.

In further embodiments the environmental control system includes an outlet, and the first medium provided to the outlet has at least one of a temperature and pressure different from the first medium provided to the first inlet.

In further embodiments the first medium is bleed air.

In further embodiments the second medium is cabin outflow air.

In further embodiments the energy extracted from the second medium within the expansion device is provided to a battery.

In further embodiments the one or more loads that receive the energy extracted from the second medium within the expansion device are external to the environmental control system.

According to another aspect, a method of operating an environmental control system of a vehicle is provided as defined by claim <NUM>.

In embodiments comprising supplying the generated electricity to one or more loads of the vehicle.

In further embodiments comprising heating the second medium directly upstream from the expansion device.

In further embodiments comprising exhausting the second medium from the expansion device overboard.

In further embodiments comprising exhausting the second medium from the expansion device into a ram air circuit.

In further embodiments the first medium is bleed air and the second medium is cabin outflow air.

Additional features and advantages are realized through the techniques of the embodiments herein. For a better understanding of the embodiments with the advantages and the features, refer to the description and to the drawings.

The following description should not be considered limiting in any way. With reference to the accompanying drawing, like elements are numbered alike:
The Figure is a simplified schematic diagram of a system according to an embodiment.

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 Figure.

Embodiments herein provide an environmental control system of an aircraft that mixes mediums from different sources and uses energy from one or more of the different sources to power the environmental control system and to provide cabin pressurization and cooling at a high fuel burn efficiency. The mediums described herein are generally types of air; however, it should be understood that other mediums, such as gases, liquids, fluidized solids, or slurries are also contemplated herein.

With reference now to the Figure, a schematic diagram of a portion of an environment control system (ECS) <NUM>, such as a 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 are also within the scope of the disclosure. As shown in the Figure, the system <NUM> can receive a first medium A1 at an inlet <NUM> and provide a conditioned form of the first medium to one or more loads, such as a volume <NUM> for example, via an outlet <NUM>. In embodiments where the environmental control system <NUM> is used in an aircraft application, the first medium A1 is bleed air, which can be pressurized air originating from (e.g., being "bled" from) an engine or auxiliary power unit of the aircraft. It shall be understood that one or more of the temperature, humidity, flow rate, and pressure of the bleed air can vary based upon the compressor stage from which the air is drawn and revolutions per minute of the engine, or the auxiliary power unit from which the air is drawn.

The system <NUM> is also configured to receive a second medium A2 via a second inlet <NUM>, such as from the volume <NUM>. In one embodiment, the volume <NUM> is the cabin of an aircraft and the second medium A2 is cabin discharge or outflow air, which is air leaving the volume <NUM> that would typically be discharged overboard. In some embodiments, the system <NUM> is configured to extract work from the second medium A2. In this manner, the pressurized air A2 of the volume <NUM> can be utilized by the system <NUM> to achieve certain operations.

The environmental control system <NUM> includes a ram air circuit <NUM> including a shell or duct, illustrated schematically at <NUM>, within which one or more heat exchangers are located. The shell <NUM> can receive and direct a medium, such as ram air AR for example, through a portion of the system <NUM>. The one or more heat exchangers <NUM> arranged within the shell <NUM> may be referred to as ram heat exchangers and are built for efficient heat transfer from one medium to another. Within the one or more heat exchangers <NUM>, ram air AR, such as outside air for example, acts as a heat sink to cool a medium passing there through, for example the first medium A1. 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. As shown, a fan <NUM> is disposed within the ram air shell <NUM>. The fan <NUM> is operable to force via push or pull methods a medium (e.g., ram air) through the shell <NUM> across the one or more ram heat exchangers <NUM>.

The system <NUM> additionally comprises at least one compression device. In the illustrated, non-limiting embodiment, the compression device <NUM> 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 the compression device <NUM> include an air cycle machine, a three-wheel air cycle machine, a four-wheel air cycle machine, etc..

As shown, the compression device <NUM> includes a compressor <NUM>, a turbine <NUM>, and a power turbine <NUM> operably coupled to each other via a shaft <NUM>. The compressor <NUM> is a mechanical device that raises 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. As shown, the compressor <NUM> is configured to receive and pressurize the first medium A1. The turbine <NUM> and the power turbine <NUM> are mechanical devices that expand a medium and extract work therefrom (also referred to as extracting energy). In the compression device <NUM>, the turbines <NUM>, <NUM> are configured to drive the compressor <NUM> via the shaft <NUM>.

The system <NUM> additionally comprises at least one expansion device <NUM>. The expansion device <NUM> is a mechanical device, similar to the compression device <NUM>, and 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 by raising and/or lowering pressure and by raising and/or lowering temperature). Examples of the expansion device <NUM> include, but are not limited to, a simple air cycle machine or a tip turbine fan etc..

In the illustrated, non-limiting embodiment, the expansion device <NUM> is a turbo-generator including a turbine <NUM> and an electrical generator <NUM> operably coupled via a shaft <NUM>. The turbine <NUM> is a mechanical device that expands a medium and extracts work therefrom. In the expansion device <NUM>, the turbine <NUM> drives an impeller (not shown) of the generator <NUM> via the shaft <NUM>. In a non-limiting embodiment, the turbine <NUM> can comprise a nozzle configured to accelerate a medium supplied thereto for entry into a turbine impeller (not shown).

The system <NUM> additionally includes at least one dehumidification system <NUM>. In the illustrated, non-limiting embodiment, the dehumidification system <NUM> includes a reheater <NUM>, a condenser <NUM>, and a water extractor <NUM>. The reheater <NUM> and the condenser <NUM> are particular types of heat exchangers. The water extractor <NUM> is a mechanical device that performs a process of removing water from the medium. Together, the condenser <NUM>, the water extractor <NUM>, and/or the reheater <NUM> can be combined to form a medium pressure water separator.

The elements of the system <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 system <NUM> can be regulated to a desired value.

The system <NUM> is operable in a plurality of modes, selectable based on a flight condition of the aircraft. In an embodiment, the system <NUM> is operable in a first mode when the aircraft is on the ground and in a second mode when the aircraft is in flight, such as high altitude cruise, climb, and/or descent for example.

During operation in the first mode, the first medium A1 enters the ECS <NUM> at the inlet <NUM>. In the illustrated, non-limiting embodiment, the first medium A1 is provided from the inlet <NUM> directly to the compressor <NUM>. However, embodiments where one or more components, such as a heat exchanger for example, are arranged upstream from the compressor <NUM> are also within the scope of the disclosure. Within the compressor <NUM>, the first medium A1 is compressed causing the temperature and the pressure of the first medium A1 to increase. The heated, pressurized first medium A1 output from the compressor <NUM> is then provided to an outflow heat exchanger <NUM>. In an embodiment, the outflow heat exchanger <NUM> utilizes the second medium A2, such as cabin discharge air sourced from the volume <NUM> for example, to cool the first medium A1.

From the outflow heat exchanger <NUM>, the heated second medium A2 is expanded across the turbine <NUM> of the expansion device and work is extracted therefrom. The work extracted by the turbine <NUM> of the expansion device <NUM> drives the generator <NUM>, thereby creating electricity. In an embodiment, the electricity created within the generator may be distributed to one or more electrical loads of the aircraft, such as remote from the environmental control system <NUM>, or alternatively, may be stored within a battery (not shown). The cooled, reduced pressure second medium A2 output from the turbine <NUM> of the expansion device <NUM> may be exhausted overboard, or alternatively, may be dumped into the ram air circuit <NUM>, upstream or downstream of the at least one heat exchanger <NUM>. In embodiments where the second medium A2 is provided to the ram air circuit <NUM>, this additional air may be used to supplement the cooling performed by the ram air circuit <NUM>.

The first medium A1 output from the outflow heat exchanger <NUM> is provided to at least one ram heat exchanger <NUM>. As shown, the fan <NUM> is used to move air, such as ram air for example, through or across the ram air heat exchanger <NUM> to further cool the temperature of the first medium A1 within the ran air heat exchanger <NUM>. In the illustrated, non-limiting embodiment, the fan <NUM> is a tip turbine fan driven by a motor <NUM>. However, in other embodiments, the fan <NUM> may be part of the compression device or alternatively, the expansion device <NUM>.

The first medium A1 output from the ram air heat exchanger <NUM> is provided to the power turbine <NUM> of the compression device <NUM>. The first medium A1 is expanded across the power turbine <NUM> and work is extracted therefrom. The work extracted by the turbine <NUM> is used to drive the compressor <NUM> via shaft <NUM>.

The cooled, reduced pressure first medium A1 output from the power turbine <NUM> is typically provided to the dehumidification system <NUM>. The first medium A1 is configured to flow through the reheater <NUM>, the condenser <NUM>, and the water extractor <NUM> sequentially. The first medium A1 is cooled and further cooled within the reheater <NUM> and the condenser <NUM>, respectively, causing any moisture within the first medium A1 to condense. This moisture is then removed within the water extractor <NUM> and the first medium A1 is provided again to the reheater <NUM>. Within this second pass through the reheater <NUM>, the first medium A1 is at least partially heated to produce a warm, dry first medium A1.

From the second pass of the reheater <NUM>, the warm, dry first medium A1 may be provided to an inlet of the turbine <NUM>. The warm, dry first medium A1 is expanded across the turbine <NUM> and work is extracted therefrom. The work extracted by the turbine <NUM> is combined with the work extracted from the power turbine <NUM> to drive the compressor <NUM> via the shaft <NUM>. The cooled, reduced pressure first medium A1 output from the turbine <NUM> is then provided to the condenser <NUM>, where the first medium is heated prior to being delivered to one or more loads of the aircraft, such as the volume <NUM> for example.

Operation of the ECS <NUM> in a second mode of operation, such as when the aircraft is in flight, is similar to operation in the first mode. However, during operation in the second mode, the flow of the first medium A1 is configured to bypass the power turbine <NUM>. As a result, the compressor <NUM> is driven solely by the energy extracted via turbine <NUM>. As previously described, the first medium A1 is pressurized and heated within the compressor <NUM>, is partially cooled within the outflow heat exchanger <NUM>, and is further cooled within the ram air heat exchanger <NUM>. The fan <NUM> may only be used to move ram air through the ram air circuit <NUM> in instances where the ram recovery, for example the pressure of the ram air provided to the ram air circuit <NUM>, is insufficient to drive the ram air flow across the heat exchanger <NUM>. In an embodiment, the fan <NUM> is only driven when the aircraft is on the ground, at low altitude, or in a low speed operation. However, during cruise at high altitude for example, the fan <NUM> need not be used to facilitate movement of the ram air.

After making one or more passes through the ram air heat exchanger <NUM>, the first medium A1 is configured to flow through a bypass conduit <NUM>, directly to an inlet of the turbine <NUM>. In the second mode of operation, the valve V1 is at least partially open, thereby allowing some or all of the first medium A1 to flow into the bypass conduit <NUM>. The cooled, reduced pressure first medium A1 output from the turbine <NUM> is then provided to the condenser <NUM>, where the first medium A1 before being delivered to one or more loads of the aircraft, such as the volume <NUM> for example. In embodiments where the valve V1 is only partially open, a portion of the first medium A1 will follow the flow path described with respect to the first mode.

In both the first and second modes of operation, the second medium A2 is heated, such as via a heat exchange relationship with the first medium A1, to increase and/or maximize the energy extracted from the second medium A2, and therefore the electrical energy that can be collected or generated using the second medium A2.

Aspects of the embodiments are described herein with reference to flowchart illustrations, schematics, and/or block diagrams of methods, apparatus, and/or systems according to embodiments. Further, the descriptions of the various embodiments have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope of the invention as defined by the claims. The terminology used herein was chosen to best explain the principles of the embodiments, the practical application or technical improvement over technologies found in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.

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 more other features, integers, steps, operations, element components, and/or groups thereof.

Claim 1:
An environmental control system of a vehicle comprising:
a first inlet (<NUM>) for providing a first medium;
a second inlet for providing a second medium;
a compression device (<NUM>) arranged in fluid communication with the first inlet;
an expansion device (<NUM>) separate from the compression device, the expansion device being arranged in fluid communication with the second inlet, wherein energy extracted from the second medium within the expansion device is provided to one or more loads of the vehicle; and
further comprising a heat exchanger (<NUM>) arranged upstream from the expansion device relative to a flow of the second medium, wherein heat is transferred from the first medium to the second medium in the heat exchanger; characterized in that:
the compression device includes a compressor (<NUM>), turbine (<NUM>), and power turbine (<NUM>), operably coupled via a shaft (<NUM>); and wherein both the turbine and the power turbine are configured to receive a flow of the first medium; and wherein the environmental control system is operable in a plurality of modes including a first mode and a second mode, wherein in the first mode, energy extracted from both the turbine and the power turbine is used to operate the compressor, and in the second mode, energy extracted from only the turbine is used to operate the compressor.