Patent Description:
In general, contemporary air condition systems are supplied a pressure at cruise that is approximately <NUM> bar to <NUM> bar (<NUM> psig to <NUM> psig). 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.

Early air conditioning systems commonly used on an aircraft, were typically driven by pressurized air suppled from a turbo compressor. High pressure air drawn from an engine is delivered to a turbo compressor to compress outside air within the turbo compressor. The compressed outside air output from turbo compressor then passes through a series of heat exchangers, an air cycle machine, and a high pressure water separator where the air is cooled and dehumidified. The resulting cool dry air is provided to the cabin, flight deck, and one or more other systems of the aircraft. <CIT> discloses a system and method for providing conditioned air to an aircraft cabin.

According to a first aspect, there is provided an environmental control system according to claim <NUM>.

In embodiments the second medium is provided from a bleed air source including at least one of an engine and an auxiliary power unit of the aircraft.

In embodiments the first medium is fresh outside air.

In embodiments the second medium output from the second turbine is exhausted overboard.

In embodiments comprising a ram air circuit, wherein the second medium output from the second turbine is provided to the ram air circuit.

In embodiments the second turbine is a dual entry turbine operable to receive the flow of first medium output from the compressor and the flow of second medium simultaneously.

In embodiments the second turbine includes a first inlet and a second inlet, the flow of first medium output from the compressor being provided to the first inlet and the flow of second medium being provided to the second inlet.

In embodiments comprising a ram air circuit including a ram air duct having at least one heat exchanger positioned therein.

In embodiments the at least one heat exchanger is configured to receive the flow of medium output from the compressor.

In embodiments the at least one heat exchanger includes a first heat exchanger and a second heat exchanger, the first heat exchanger is configured to receive the flow of medium output from the compressor, and the second heat exchanger is configured to receive the flow of second medium.

In embodiments the second heat exchanger is positioned upstream from the second turbine relative to the flow of second medium.

In embodiments the environmental control system is operable in a plurality of modes including a first mode and a second mode.

In embodiments the environmental control system is operable in the first mode when an ambient temperature is at or above a design point of the environmental control system.

In embodiments the environmental control system is operable in the second mode when an ambient temperature is below a design point of the environmental control system.

In embodiments the bypass valve is in a closed position during operation in the first mode and the bypass valve is in an open position during operation in the second mode.

According to another aspect, there is provided a method of operating an environmental control system of an aircraft according to claim <NUM>.

In embodiments the environmental control system is transformed from the first mode of operation to the second mode of operation by opening a first bypass valve.

In embodiments the environmental control system is transformed from the first mode of operation to the third mode of operation by opening a second bypass valve.

In embodiments providing the second medium to the environmental control system includes drawing bleed air from an engine of the aircraft.

Additional features and advantages are realized through the techniques of the embodiments herein. Other embodiments are described in detail herein and are considered a part of the claims. For a better understanding of the embodiments with the advantages and the features, refer to the description and to the drawings.

The subject matter is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The forgoing and other features, and advantages thereof are apparent from the following detailed description, by way of example only and taken in conjunction with the accompanying drawings in which:.

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 FIGS.

Embodiments herein provide an environmental control system of an aircraft that receives multiple mediums from different sources and uses energy from one or more of the mediums to operate 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 may also be contemplated herein, but are not covered by the claimed invention.

With reference now to <FIG>, a schematic diagram of an environment control system (ECS) <NUM> is depicted by way of background. 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 FIG. , the system <NUM> can receive a first medium A1 at a first inlet <NUM> and provide a conditioned form of the first medium A1 to a volume <NUM>. In embodiments where the environmental control system <NUM> is used in an aircraft application, the first medium A1 is fresh or outside ambient air.

The system <NUM> receives a second medium A2 at an inlet <NUM>. The second medium A2 is bleed air. As used herein, the term "bleed air" includes pressurized air originating from i.e. being "bled" from, an engine or auxiliary power unit of the aircraft. It shall be understood that one or more of the temperature, humidity, and pressure of the bleed air may vary based upon the compressor stage and revolutions per minute of the engine or auxiliary power unit from which the air is drawn. For example, bleed air may be drawn from either a low pressure compressor spool or a high pressure compressor spool of an engine, and bleed air drawn from the low pressure compressor spool will have a relatively lower pressure than bleed air drawn from the high pressure compressor spool. In some embodiments, the system <NUM> is configured to extract work from the second medium A2. In this manner, the pressurized air A2 can be utilized by the system <NUM> to achieve certain operations.

The environmental control system <NUM> includes one or more heat exchangers. 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. In an embodiment, the one or more heat exchangers may be located within the shell of a RAM air circuit (not shown), such that the one or more heat exchangers may be referred to as "ram heat exchangers. " Within the one or more heat exchangers, a cooling fluid, such as outside air drawn in through a scoop for example, acts as a heat sink to cool a medium passing there through, for example the first medium A1 and/or the second medium A2. In <FIG>, the one or more heat exchangers includes a first heat exchanger <NUM>. In another example, the one or more heat exchangers includes the first heat exchanger <NUM> and a second heat exchanger <NUM>. The heat exchangers <NUM>, <NUM> may be arranged in series relative to the flow of cooling medium.

The system <NUM> additionally comprises at least one compressing device <NUM>. In the illustrated arrangement, the compressing device <NUM> of the system <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 and/or the second medium A2 by raising and/or lowering pressure and by raising and/or lowering temperature. ) Examples of the compressing device <NUM> include an air cycle machine, a three-wheel air cycle machine, a four-wheel air cycle machine, etc..

As shown, the compressing device <NUM> includes a compressor <NUM>, a turbine <NUM>, and a power turbine <NUM>, operably coupled to each other via a shaft <NUM> that is also is connected to a fan <NUM>. The compressor <NUM> is a mechanical device that raises a pressure of a medium provided thereto 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 second medium A2.

Each of the turbine <NUM> and the power turbine <NUM> is a mechanical device that expands a medium and extracts work therefrom (also referred to as extracting energy). In the compressing device <NUM>, the power turbine <NUM> drives the compressor <NUM> and the fan <NUM> via the shaft <NUM>. In the arrangements shown in <FIG> and <FIG>, by way of background only, a single flow of a medium, such as the second medium A2 for example, is provided to the power turbine <NUM>. However, in embodiments of the invention, as shown in <FIG> and <FIG>, the power turbine <NUM> can be a dual entry turbine that includes multiple inlet fluid flow paths, such as an inner flow path and an outer flow path, to enable mixing of alternative medium flows within the turbine or at the exit of the power turbine <NUM>. In an embodiment, the inner flow path is a first diameter and the outer flow path is a second diameter. Further, the power turbine <NUM> may include a first nozzle configured to accelerate the first medium for entry into a turbine impeller and a second nozzle configured to accelerate the second medium for entry into the turbine impeller. The turbine impeller can be configured with a first gas path configured to receive the first medium from the first nozzle and with a second gas path configured to receive the second medium from the second nozzle.

The fan <NUM> is a mechanical device that can force, via push or pull methods, a medium (e.g., ram air) across the one or more heat exchangers <NUM> and at a variable cooling to control temperatures.

The system <NUM> additionally includes at least one dehumidification system <NUM>. In the illustrated example, the dehumidification system <NUM> includes a condenser <NUM> and a water extractor <NUM>. The condenser <NUM> is a particular type of heat exchanger and the water extractor <NUM> is a mechanical device that removes water from a medium. The condenser <NUM> and the water extractor <NUM> are arranged to receive the first medium A1, and in some embodiments, both the first medium A1 and the second medium A2. The configuration of the at least one dehumidification system <NUM> may vary. It should be understood that the disclosed configuration of the dehumidification system is described for background only.

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 can be regulated to a desired value. For instance, a first valve V1 is configured to control a supply of the second medium A2 provided to the system <NUM>. A second valve V2 may be operable to allow a portion of a medium, such as the first medium A1, to bypass the turbine <NUM> of the compression device <NUM>. As a result, operation of the second valve V2 may be used to add heat and to drive the compression device <NUM> during failure modes. In embodiments where the power turbine <NUM> is a dual entry turbine, a third valve V3 may be similarly operable to control a supply of the first medium output from the compressor <NUM> to the power turbine <NUM> as is illustrated in <FIG> and <FIG>.

The environmental control system of <FIG> may be operable in a plurality of modes based on a flight condition of the aircraft. For example, the environmental control system <NUM> may be operable in a first mode when the ambient temperature is at or above a selected design point of the system <NUM>. In the first mode of operation, valve V1 is opened to draw a high pressure, hot second medium A2, such as bleed air, from a bleed source, such as the turbine engine or the auxiliary power unit. This second medium A2 then enters the power turbine <NUM>, such as via a nozzle. The high pressure, high temperature second medium A2 is expanded across the power turbine <NUM> and work extracted from the hot high pressure air. This extracted work drives the compressor <NUM> via shaft <NUM>. This extracted work also drives the fan <NUM>, which is used to move air through the heat exchanger <NUM>, via a ram air duct (not shown). The second medium output from the power turbine <NUM> may be exhausted overboard, into the ambient atmosphere.

At the same time, a flow of cool, low pressure first medium A1, fresh outside air, is provided to an inlet of the compressor <NUM>. The act of compressing the fresh outside air, heats the fresh outside air. The compressed first medium A1 provided at the outlet of the compressor <NUM> (shown as CA1) then passes through an ozone converter <NUM> before being provided to the heat exchanger <NUM>. Within the heat exchanger <NUM>, the compressed first medium CA1 is cooled via a flow of ram air. Embodiments where other components, such as an outflow heat exchanger (not shown) for example, are positioned directly downstream from or upstream from the heat exchanger <NUM> are also within the scope of the disclosure.

The warm first medium A1 is then provided to at least a portion of the dehumidification system <NUM>. As shown, the first medium A1 output from the heat exchanger <NUM> is provided sequentially to the condenser <NUM> and water extractor <NUM> of the dehumidification system <NUM> where any free moisture within the first medium A1 is condensed and removed, to produce cool high-pressure air. This cool, high pressure first medium A1 then enters the turbine <NUM> through an inlet or nozzle.

The cool, high pressure first medium A1 is expanded across the turbine <NUM> and work is extracted therefrom. In combination with the work resulting from the power turbine <NUM>, this extracted work drives the compressor <NUM> and the fan <NUM>, as previously described. The cold, for example freezing, first medium A1 output from the turbine <NUM> enters the condenser <NUM> to cool the warm first medium A1 leaving the heat exchanger <NUM>. The first medium A1 is then sent to one or more downstream loads and/or locations of the aircraft. In an embodiment, the first medium A1 output from the turbine <NUM> and the condenser <NUM> is mixed with another medium (not shown), such as recirculated air for example, such as provided from the volume <NUM>. The mixture of conditioned fresh air and recirculated air may then be used to condition the volume <NUM>, such as the cabin and flight deck of an aircraft for example.

With continued reference to <FIG>, the second mode of the environmental control system <NUM> is associated with operation of the system <NUM> at ambient temperatures below a selected design point of the environmental control system. In the second mode of operation, the bypass valve V2 is open, thereby allowing at least a portion of the first medium A1 output from the compressor <NUM> to bypass the heat exchanger <NUM>, the first pass through the condenser <NUM>, the water extractor <NUM>, and the turbine <NUM>. In such embodiments, at least a portion of the first medium A1 output from the compressor <NUM> is provided downstream from an outlet of the turbine <NUM>, before being provided to the condenser <NUM> and then delivered to one or more downstream loads, such as to condition the volume <NUM>.

The environmental control system <NUM> of <FIG> operates similarly to the environmental control system <NUM> of <FIG>, except that in the illustrated, non-limiting embodiment, the power turbine <NUM> is a dual entry turbine. Accordingly, an additional conduit <NUM> connects the outlet of the compressor <NUM> to a second inlet or nozzle of the power turbine <NUM>. A valve V3 is operable to selectively control a flow of the first medium A1 output from the compressor to the power turbine <NUM>.

During operation of the system of <FIG> in a first mode, when the ambient temperature is at or above a selected design point of the system <NUM>, valve V3 is at least partially open. Accordingly, the hot, medium pressure fresh air output from the compressor <NUM> is split into a first portion, A1a and a second portion A1b. The first portion of the first medium output from the compressor <NUM> is provided to power turbine <NUM> via the conduit <NUM>, and work is extracted therefrom. The first portion A1a of the first medium and the second medium exhausted from the power turbine <NUM> may be dumped overboard, or alternatively, into the ram air circuit. The second portion A1b of the first medium A1 output from the compressor <NUM> is provided to the ozone converter <NUM>, the heat exchanger <NUM>, and the remainder of the components of the system <NUM> as previously described with respect to <FIG>.

With reference now to <FIG>, the illustrated environmental control system <NUM> is similar to the system of <FIG>, and isshown and described for background only. However, in the arrangement illustrated in <FIG>, the system <NUM> additionally includes a second heat exchanger <NUM> arranged downstream from the first heat exchanger <NUM> relative to a flow of ram air within a ram air circuit defined by a ram air shell <NUM>. In a first mode of operation, valve V1 is open and a high pressure, high temperature second medium A2, such as bleed air, is configured to pass through the second heat exchanger <NUM> before being provided to power turbine <NUM>. Within the second heat exchanger, the high pressure, high temperature second medium A2 is cooled via a heat exchange relationship with the ram air flow. With the power turbine <NUM>, the high pressure, warm temperature second medium A2 is expanded across the power turbine <NUM> and work extracted therefore. This work drives the compressor <NUM> and the fan <NUM> via shaft <NUM>. Operation of the fan <NUM> moves air through the ram air circuit, across the heat exchangers <NUM>, <NUM>. The second medium A2 output from the power turbine <NUM> may be exhausted overboard, into the ambient atmosphere, or alternatively, may be dumped into the ram air circuit, for example upstream from one or both of the heat exchangers <NUM>, <NUM>.

At the same time, a flow of cool, low pressure first medium A1, fresh outside air, is provided to an inlet of the compressor <NUM>. The act of compressing the fresh outside air, heats the fresh outside air. The compressed first medium A1 provided at the outlet of the compressor <NUM> may then pass through an ozone converter <NUM> before being provided to the first heat exchanger <NUM>. Within the heat exchanger <NUM>, the first medium A1 is cooled via the flow of ram air.

The warm, moist first medium A1 is then provided to at least a portion of the dehumidification system <NUM>. As shown, the first medium A1 output from the first heat exchanger <NUM> is provided sequentially to the condenser <NUM> and water extractor <NUM> of the dehumidification system <NUM> where any free moisture within the first medium A1 is condensed and removed, to produce cool high-pressure air. This cool, high pressure first medium A1 then enters the turbine <NUM> through an inlet or nozzle.

The cool, high pressure first medium A1 is expanded across the turbine <NUM> and work is extracted therefrom. In combination with the work resulting from the power turbine <NUM>, this extracted work drives the compressor <NUM> and the fan <NUM>, as previously described. The cold, for example freezing, first medium A1 output from the turbine <NUM> enters the condenser <NUM> to cool the warm first medium A1 leaving the heat exchanger <NUM>. The first medium A1 is then sent to one or more downstream loads and/or locations of the aircraft. As previously described, in an embodiment, the first medium A1 output from the turbine <NUM> and the condenser <NUM> is mixed with another medium, such as recirculated air, such as provided from the volume <NUM> for example. The mixture of conditioned fresh air A1 and recirculated air (not shown) may then be used to condition the volume <NUM>, such as the cabin and flight deck of the aircraft for example.

With continued reference to <FIG>, a second mode of the environmental control system <NUM> may be associated with operation at ambient temperatures below a selected design point of the environmental control system <NUM>. In the second mode of operation, the bypass valve V2 is open, thereby allowing at least a portion of the first medium A1 output from the compressor <NUM> to bypass the first heat exchanger <NUM>, a first pass through the condenser <NUM>, the water extractor <NUM>, and the turbine <NUM>. In such embodiments, at least a portion of the first medium A1 output from the compressor <NUM> is provided downstream from an outlet of the turbine <NUM>, before being provided to the condenser <NUM> and then delivered to one or more downstream loads, such as to condition the volume <NUM>.

The environmental control system <NUM> of <FIG> is substantially identical to the environmental control system <NUM> of <FIG>, except that in the illustrated, non-limiting embodiment, the power turbine <NUM> is a dual entry turbine. Accordingly, an additional conduit <NUM> connects the outlet of the compressor <NUM> to a second inlet or nozzle of the power turbine <NUM>. A valve V3 is operable to selectively control a flow of the first medium A1 output from the compressor to the power turbine <NUM>.

During operation of the system of <FIG> in a first mode, when the ambient temperature is at or above a selected design point of the system <NUM>, valve V3 is at least partially open. Accordingly, the hot, medium pressure fresh air A1 output from the compressor <NUM> is split into a first portion A1a and a second portion A1b. The first portion A1a of the first medium A1 output from the compressor <NUM> is provided to power turbine <NUM> via the conduit <NUM>, and work is extracted therefrom. The first portion A1a of the first medium and the second medium A2 exhausted from the power turbine <NUM> may be dumped overboard, or alternatively, into the ram air circuit as shown. The second portion A1b of the first medium A1 output from the compressor <NUM> is provided to the ozone converter <NUM>, the heat exchanger <NUM>, and the remainder of the components of the system <NUM> as previously described with respect to <FIG>.

The systems illustrated in <FIG> and <FIG>, are similar to the systems of <FIG> and <FIG>, respectively, with <FIG> being shown and described for background only. Although the condenser <NUM> is operable to cool the flow of first medium A1 such that the water therein may be removed from the flow in the water extractor <NUM>, in the systems shown in <FIG> and <FIG>, the condenser <NUM> of the dehumidification system <NUM> is no longer arranged in fluid communication with the outlet of the turbine <NUM>. Rather, the condenser <NUM> is configured to receive fluid from the outlet of the power turbine <NUM>. By positioning the condenser in fluid communication with the power turbine <NUM>, the flow of second medium A2 used to cool the first medium A1 within the condenser is at a temperature above freezing. As a result, the potential for the formation of ice within the condenser <NUM> is generally reduced. In addition, the pressure of the air provided to the volume <NUM> will remain generally equal to the pressure of the air output from the turbine <NUM>. After passing through this condenser <NUM>, the second medium A2 may be exhausted overboard, or alternatively, into the ram air circuit, upstream from the ram air heat exchangers <NUM>, <NUM>.

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 defined in the appended 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.

The flow diagrams depicted herein are just one example. There may be many variations to this diagram or the steps (or operations) described therein without departing from the scope defined in the appended claims. For instance, the steps may be performed in a differing order or steps may be added, deleted or modified. All of these variations are considered a part of the claims.

Claim 1:
An environmental control system (<NUM>) of an aircraft comprising:
a compressing device (<NUM>) including:
a compressor (<NUM>) and a turbine (<NUM>) configured to receive a flow of first medium sequentially; and
a second turbine (<NUM>) arranged in fluid communication with an outlet of the compressor, the second turbine being configured to receive a flow of second medium distinct from the first medium;
a dehumidification system (<NUM>) in fluid communication with the turbine; and
a first bypass valve (V2) configured to divert at least a portion of the flow of the first medium output from the compressor around the turbine; and
a second bypass valve configured to divert at least a portion of the flow of first medium output from the compressor to the second turbine;
wherein the first medium is fresh or outside ambient air; and
wherein the second medium is bleed air.