Patent Application
20160362188
The subject matter disclosed herein generally relates to fuel tank inerting apparatuses for aircraft and, more particularly, to fuel tank inerting apparatus and processes configured to supply inert gas in an aircraft.
In general, in air conditioning systems of aircraft, cabin pressurization and cooling is powered by engine bleed pressures at cruise altitudes. For example, pressurized air from an engine of the aircraft is provided to a cabin through a series of systems that alter the temperatures and pressures of the pressurized air. To power this preparation of the pressurized air, generally the source of energy is the pressure of the air itself As a result, traditional air conditioning systems require relatively high pressures at cruise altitudes, that is, the ambient air must be compressed. The relatively high pressures required in current system provide limited efficiency with respect to engine fuel burn.
The air bled from engines may be used for environmental control systems, such as used to supply air to the cabin and to other systems within an aircraft. Additionally, the air bled from engines may be supplied to inerting apparatuses to provide inert gas to a fuel tank. In most cases, the air must be conditioned, e.g., altered in temperature and/or pressure, prior to being supplied to the desired location. The air to be supplied to an inerting apparatus may be desired to be at a higher pressure than the ambient air at altitude, e.g., at about 30 psig. Thus, the air must be compressed to the higher desired pressure, which requires energy and thus may impact the efficiency of the aircraft.
According to one embodiment, a system for supplying conditioned air to an inerting apparatus of an aircraft is provided. The system includes a first air supply source and a first flow path fluidly connecting the first air supply source to an inerting apparatus. A compressor device is driven by a turbine. A second air supply source and a second flow path fluidly connecting the second air supply source to the turbine of the compressor device is provided. A first valve located within the first flow path and configured to be open in a first state and closed in a second state, the first valve configured to allow a supply of air to flow from the first air supply source to the inerting apparatus directly, and a second valve located within the second flow path and configured to be closed in the first state and open in the second state, the second valve configured to allow a supply of air to flow from the second air supply source to drive the turbine of the compressor device. When in the second state, the compressor device is operated to compress air from the first air supply source prior to the air being supplied to the inerting apparatus.
According to another embodiment, a method of supplying air to an inerting apparatus of an aircraft is provided. The method includes determining an operational status of an aircraft, engaging a first state of an inerting apparatus supply system if the aircraft is in a first mode of operation, the first state configured to supply air from a first source directly to an inerting apparatus, engaging a second state of the inerting apparatus supply system if the aircraft is in a second mode of operation, the second state configured to compress air from the first source prior to being supplied to an inerting apparatus; and supplying air from the first source to the inerting apparatus. When in the second state, the method further comprises supplying air from a second source and driving a turbine to compress the air from the first source.
Technical effects of embodiments of the invention include an efficient inerting apparatus supply system and process configured to efficiently operate regardless of the operational status of an aircraft. Further technical effects of various embodiments of the invention include driving a turbine with air from a cabin air supply source.
The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification.
The foregoing and other features and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
Air conditioning systems of aircraft may be configured to provide cabin pressurization and cooling at low engine bleed pressures while the aircraft is at cruise altitudes. Current air conditioning systems may be supplied with air pressure at cruise altitudes that is approximately 30 psig to 35 psig above cabin pressure. In traditional cabin air conditioning systems, high pressure air from either an engine or an APU may, for example, pass through a series of heat exchangers, an air cycle machine, and a high pressure water separator where the air is cooled and dehumidified. The cold dry air may then be used to cool the cabin, flight deck, and other airplane systems. The high pressure air may also be used for other systems, such as inerting apparatuses.
However, some cabin air conditioning systems may employ or operate with air that is only 5 psig or lower above cabin pressure. That is, some systems may operate at pressures significantly lower than the 30 to 35 psig of prior systems. The lower pressures may create issues for other systems that operate using the same bleed air. For example, fuel tank inerting apparatuses may employ bleed air both for operation and as an air supply. However, fuel tank inerting apparatuses may require air at higher air pressures, e.g., approximately 30 psig, to operate properly. In such systems and configurations, additional pressurization of the air to be used in the inerting apparatus may be required.
Turning to
As shown in
In system 100 of
However, when an aircraft is cruising at cruise altitudes, additional compression may be required to be performed upon the air provided from the first air supply source 102. In the embodiment of
In this approach, the bleed air from the first air supply source 102 is pressurized by a compressor 122 and supplied to the inerting apparatus 114. The compressor 122 is driven by a turbine 124 that is operationally connected to the compressor 122. The turbine 124 of the system 100 is driven by air from a second air supply source 128 and passes through a second flow path 126. That is, air is supplied from a second air supply source 128, flows into the second flow path 126, passes through a heat exchanger 130, and then drives the turbine 124. In this embodiment, the second air supply source 128 is the cabin and the air is cabin air. After driving the turbine 124, the cabin air is expelled or exhausted overboard at exhaust 132.
The heat exchanger 130 is configured to allow the air from the first air supply source 102 to be in thermal contact with the air from the second air supply source 128, thus conditioning the air that will be supplied to the inerting apparatus 114. For example, the heat exchanger 130 may be configured to maintain the air supplied to the inerting apparatus 114 at an appropriate temperature and/or to keep the discharge of the air from the turbine 124 above freezing.
The two sources of air 102, 128 are controlled, in part, by operation of one or more valves. As shown in
A first state of the system 100 is when the first valve 112 is open and the second valve 134 is closed. In this state, the air from the first air supply source 102 flows directly to the inerting apparatus 114. The first state is engaged when the air pressure is sufficiently high to not require further conditioning, such as during taxiing, take-off, ascent, descent, and landing.
In a second state, the first valve 112 is closed, and the air from the source 102 is directed at junction 116 along a part 134 of the first flow path 110 and into the compressor 122 where the air is compressed. The air then leaves the compressor 122 and flows along flow path 136. The compressed air the passes through the heat exchanger 130 and thermally communicates with the air from the second air supply source 128. The air then exits the heat exchanger 130 into the exit flow path 120 and is supplied to the inerting apparatus 114. Also in the second state, the second valve 134 is opened and air flows from the second air supply source 128, into the heat exchanger 130, drives the turbine 124, and then is exhausted at exhaust 132.
Advantageously, the above described embodiment of the invention employs an existing air supply source to drive a turbine which is used to compress and condition air to be supplied to an inerting apparatus even if the air is at a low pressure.
Turning now to
The primary difference between system 200 of
In system 200, similar to the embodiment of
Turning now to
The primary difference between system 100 of
Thus, in operation, when in the first state and the first valve 312 is open, system 300 operates similar as described above for the first state. That is, in the first state, all of the air supplied by first air supply source 302 is directed to the inerting apparatus 314 without additional conditioning.
However, in the second state, the first valve 312 closes and the second valve 334 opens, allowing for the air in flow path 310 to be split at junction 338 with a portion flowing into second flow path 326 and becoming the second air supply source. The other portion of the air from the first air supply source continues along part 334 of first flow path 310 to flow toward the compressor 322. Thus, a portion of the air drives the turbine 324 to drive the compressor 322 to compress a different portion of the air. The air that drives the turbine 324 then may pass through a heat exchanger 330 and be exhausted overboard at exhaust 332. At the same time, the portion of air that is compressed by compressor 322 also passes through the heat exchanger 330 and is then supplied to the inerting apparatus.
Turning now to
At step 402, an operating status of an aircraft is determined That is, it is determined whether the aircraft is taxiing, in the process of take-off, climbing to altitude, at altitude and cruising, descending, landing, etc. This determination may be made by a controller, which may be in communication with flight controls. Alternatively, this determination may be made mechanically or otherwise based on the air pressure within an inerting apparatus air supply system. That is, the status of operation of the aircraft may inherently be determined by the air pressure within the system.
At step 404, an inerting apparatus supply state is selected or engaged. That is, if a controller is used, a decision may be made to operate in a first mode or a second state. If the system is mechanical, one of two valves may be opened while the other of the two valves may be closed, thereby automatically selecting or engaging an inerting apparatus supply state. The inerting apparatus supply state is a mode of operation of an air supply system that is configured to condition air, as necessary, for the purpose of supplying air to an inerting apparatus of an aircraft.
The first state is a state that is used when the aircraft is selected or engaged during taxi, take-off, climb, and descent. At step 406, if the first state is engaged at 404, a first valve is open or opened and a second valve is closed. The valve arrangement of the first state is configured to direct air flow directly from a source, such as an engine bleed port, an APU, etc., to the inerting apparatus, with minor conditioning, such as passing the air through a heat exchanger prior to entering the inerting apparatus at step 408.
The first state may be selected or engaged because the supply air may be at a sufficiently high pressure that it can be supplied directly to the inerting apparatus. As is known in the art, inerting apparatuses may require an air supply having an air pressure of about 30 psig. Thus, when in the first state, the air may already have a pressure sufficiently close to 30 psig that only minimal conditioning is required.
However, if at step 404, the second state is selected or engaged, the second valve will be opened and the first valve will be closed at step 410. This occurs when a controller instructs the system to operate in the second state, such as when the aircraft is at altitude and the supply air has a much lower pressure. Because of this, the air must be compressed to a higher pressure prior to being supplied to an inerting apparatus. Thus, with the second valve opened at step 410, air may be directed to drive a turbine at step 412. The turbine may be operationally connected to a compressor and, at step 414, the air to be supplied to the inerting apparatus may be compressed by the compressor.
The compressed air is then passed through a heat exchanger at step 416 to adjust the temperature of the air after compression. The compressed air is then supplied to the inerting apparatus at step 418.
When there is a change in the operational status of the aircraft, the inerting apparatus supply state may be adjusted. For example the process 400 may be repeated, starting with step 402 to determine the operational status of the aircraft. This may be initiated by a controller or a change in the air pressure within the system which may change the state of the valves.
In view of the above, it will be appreciated by those of skill in the art that, in some embodiments, the first and second valves may be configured to be open and closed based on a pressure of the air that is upstream of the valve. For example, when the pressure is at or near a predetermined value, such as 30 psig, the first valve may be opened or in an open state, and the second valve may be closed. However, when the pressure drops below the predetermined value, the first valve may close and the second valve may open, thus driving the turbine and compressor to increase the pressure of the air to be supplied to the inerting apparatus. In other embodiments, the valves may be electronically controlled by a controller or other device, or may be electrically controlled by a switch or other device that is configured to change based on the air pressure within the inerting apparatus supply system or based on a flight status or other factor, such as altitude.
Advantageously, embodiments of the invention provide an air supply system for an inerting apparatus of an aircraft that is configured to supply air at an appropriate pressure while maintaining and/or improving efficiency of the aircraft. For example, in accordance with some embodiments, advantageously, cabin air may be used to condition air within the air supply system, both to change the pressure and the temperature of the air to be supplied to an inerting apparatus.
Advantageously, systems and processes in accordance with various embodiments of the invention may employ air and the associated air pressures from pre-existing systems to drive a turbine and compressor without the need to use other energy in the system, thus improving efficiency.
While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions, combinations, sub-combinations, or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments.
For example, although certain configurations are shown in
Furthermore, although a single process is described herein, this process is merely illustrative, and the order of steps and any additional steps may be added or changed without departing from the scope of the invention. For example, in some embodiments, it may be possible to eliminate step 416 (using a heat exchanger on compressed air) without departing from the scope of the invention.
Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
