CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Serial No. 61/612,483, filed March 19, 2012, titled "WIPS Fuel Cell," the entire contents of which are hereby incorporated by reference.

FIELD OF THE INVENTION

Embodiments of the present invention relate generally to the field of aerospace vehicles where fuel cell system by-products are used for wing ice protection and local peripheral applications.

BACKGROUND

Aerospace vehicles and aircraft are also often equipped with wing ice protection systems, which prevent the dangerous build-up of ice on the aircraft wing parts and the engine air intake inlets. In some instances, ice accumulates on the leading edges of wings, tailplanes, and vertical stabilizers. This airframe icing causes problems by modifying the airflow and/or aerodynamic lift over flight surfaces upon which the ice accretes, which can increase drag and decrease lift. Icing can also occur in a very short period of time, and because small to moderate amounts of icing generally cause a reduction in aircraft performance in terms of climb rates, range, endurance, maximum speed, and acceleration. As icing increases, separation of air flow from the flight surfaces can cause loss of pilot control and even unstable aircraft behavior.

The ice protection systems that are currently available use hot pressurized air output from the engine combustion chambers (bleed) which involves additional fuel consumption. Another system in development is an electro-mechanical expulsion deicing system, the use of which includes mechanical, electrical, and weight constraints, such as high power demand, electricity transport, and ice cracking. A further system uses electrically heated mats that are installed on the wings of the aircraft. Despite the electrical power that is drawn from the engine-linked generator, the heated mat option provides better power management, which leads to fuel savings. However, all of the described systems require power to be delivered directly or indirectly from the engines, which corresponds to extra fuel consumption. Accordingly, improved wing ice protection systems are desirable.

Wing ice protection systems (WIPS) require power drawn from the aircraft engines. However, use of aircraft power produces noise and C0 ₂ emissions, both of which are desirably reduced. Accordingly, it is desirable to identify ways to improve energy supply and power management by providing innovative ways to power this system.

The present inventors have thus sought new ways to generate power to run onboard components, specifically a wing ice protection system, as well as to harness beneficial by-products of that power generation for additional applications for use onboard aircraft.

The relatively new technology of fuel cells provides a promising cleaner and quieter means to supplement energy sources already aboard aircrafts. A fuel cell has several outputs in addition to electrical power, and these other outputs often are not utilized. Fuel cell systems combine a fuel source of compressed hydrogen with oxygen in the air to produce electrical and thermal power as a main product. Water and Oxygen Depleted Air (ODA) are produced as by-products, which are far less harmful than CO ₂ emissions from current aircraft power generation processes.

BRIEF SUMMARY

Embodiments of the invention described herein thus provide a wing ice protection system (WIPS) that uses fuel cell system products and by-products for various de-icing applications, as well as peripheral applications, such as fuel tank inerting. Electricity, heat, warmed water, and/or oxygen depleted air is routed to wing areas, to a fuel tank, to heater mats on or near the wings, and/or to other peripheral applications.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a top plan view of a fuel cell system providing heat for an ice protection fluid circuit. FIG. 2 shows a top plan view of a fuel cell system providing electricity to heater mats.

FIG. 3 shows a top plan view of a fuel cell system providing electrical energy for a wing application.

FIG. 4 shows a top plan view of a fuel cell system providing oxygen depleted air for a fuel tank inerting system.

DETAILED DESCRIPTION

Embodiments of the present invention provide improved systems and methods for aircraft ice protection, tank inerting, fuel warming, electrical control and other power electronics control. Referring now to the wing ice protection embodiments, ice protection is necessary on an aircraft to protect the wing parts and the engine air inlets from accumulated ice. Current ice protection systems use hot pressurized air output from the engine combustion chambers (bleed), which involves additional fuel consumption. The present inventors have determined that it is possible to use fuel cell products and by-products in order to provide wing ice protection. The ice protection systems described herein may be extended to the RAM air inlet or any other part of the aircraft structure where ice causes a problem. The fuel cell by-products used for ice protection purpose include hot water, heat, and/or electrical power.

Figure 1 illustrates one embodiment that uses a fuel cell system 10 to provide heat for an ice protection fluid circuit 12. This figure shows one fuel cell system 10 per aircraft wing, but it should be understood that a single fuel cell system may be used, or that multiple systems may be used per wing. One of the by-products of a fuel system is heat. The fuel cell system heat is transferred through a heat exchanger 14 to a fluid circuit 12 which runs under the wing skin. The fluid circuit 12 may comprise a series of conduits that allows heated fluid to flow along a desired path. The heat of the circulated fluid prevents ice accretion on the wing surface and leading edges. The fluid temperature is maintained by recirculation of the fluid to the heat exchanger 14.

A number of different types of liquid may be used. For example, in one embodiment, the liquid for circulation that is used can be the hot water generated as a by-product by the fuel cell system 10 itself. The hot water may be redirected to a tank 16 that can hold the water that is generated, and the tank 16 can be fluidly connected to the fluid circuit 12. (Water produced by the fuel cell system 10 could also be cooled and reused for power electronics cooling. This water may be stored in tank 16, or it may be re-routed to another system on-board the aircraft for cooling.) Alternatively, the fluid provided may be water from another on-board system, such as one or more of the aircraft water tanks. Other examples of potential fluids for use may be kerosene from the fuel tank, air (for example, the heated air created as a byproduct from the fuel cell system or the oxygen-depleted air), or any other appropriate fluid. Figure 1 also illustrates a pump that is used to recirculate fluid through the liquid circuit.

In an alternate embodiment, the liquid for circulation can be the fuel that is already contained in the wing tanks 18. In this case, increasing the fuel temperature can allow the warmed fuel to prevent ice accretion on the wings, but can also improve the fuel burning efficiency in the combustion chambers of the engines. This can help reduce the global fuel consumption.

Figure 2 illustrates another embodiment that uses a fuel cell system 10 for wing ice protection. In this embodiment, electricity created from the fuel cell system 10 is used to supply power to heater mats 20 that are located along the wings 22. For illustration, two heater mats 20 are shown per wing, but it should be understood that any number and size of heater mat 20 may be used, depending upon the size and type of aircraft. Heater mats 20 may either be used in anti-ice mode (with a constant power supply) or in de-ice mode (which uses on demand power supply). In the de-ice mode, when the power supply does not need to be delivered and activation of the mats is not required, the electrical power generated can be reused according to Figure 3.

Electricity is required for different applications located at the aircraft wing levels. For example, in addition to heater mats for ice protection, wings also require electronics for control and monitoring, fuel pumps, actuators, and other electrical components. For example, alternate powered systems on-board the aircraft include the environmental control system (ECS), which controls the cabin air supply, thermal control, and pressurization. Currently, the electrical energy for these systems comes from the aircraft electrical distribution network. This extra load implies additional fuel consumption as a direct use of the generator's power.

Figure 3 illustrates a fuel cell system 10 that is used to provide electrical energy to the control and monitoring units of the system (circuit [a]). The system 10 may also distribute energy to other local electrical loads like pumps, actuators, and so forth (circuit [b]). This allows the energy created by the fuel cell system 10 to be in constant use near the wing area and other aircraft areas, even if the electricity is not needed for constant delivery to the heater mats. In one embodiment, the option of a redundant architecture can be provided, where a switching control 24 is developed to select the source stack, especially when a side system (left or right) is failing. This redundant architecture is proposed as an option to cope with stack failure.

In another embodiment, there is provided a tank inerting feature. Oxygen Depleted Air (ODA) is required to inert the fuel tank. This ODA is currently provided by filtering the cabin air conditioned by the Environmental Control System (ECS). This involves additional components, including a compressor and a molecular filtering cartridge, leading to costs and mass (which means additional fuel consumption). Complementary use of the same fuel cell system 10 for alternative and/or simultaneous applications, helps to optimize the fuel cell by-products. Figure 4 illustrates use of the Oxygen Depleted Air (ODA) produced by the fuel cell system being re-used as an inerting gas for the fuel tank. Figure 4 illustrates an ODA conditioning unit 26 that can deliver the ODA to the fuel tank 18.

More details about this option may be obtained from U.S. Serial No. 61/612,493, filed March 19, 2012 titled "Fuel Cell Architecture for Inerting System" and its related PCT application, being filed concurrently herewith, the contents of which are incorporated herein by reference.

Thus, according to the activity of the ice protection system during flight, electricity, heat and/or water by-products, including ODA, can be dispatched to other local applications such fuel warning and/or fuel tank inerting. The above-described systems may be used as hybrid/combined options or individually. For example, the fuel cell system 10 may be used to power other aircraft electronics, may be used to deliver heated water to the fluid circuit 12 for hot fluid circulation, heated air to the heat exchanger, and/or energy may also be used for heater mats 20 or other electronic systems as described. Additionally or alternatively, the ODA may be used for fuel tank inerting. The available options depend upon the needs of the particular aircraft.

The fuel cell system 10 may be any appropriate fuel cell system, examples of which include but are not limited to PEMFC (Proton Exchange Membrane), SOFC (Solid Oxide), MCFC (Molten Carbonate), DMFC (Direct Methanol), AFC (Alkaline), PAFC (Phosphoric Acid) and any new fuel cell system technology comprising hybrid solutions. The hydrogen (i¾) tanks could be stored in any location of the aircraft. In the figures shown, the i¾ tanks are illustrated as being near the wing area, but they may be positioned in any appropriate location with the gas routed as appropriate.

Changes and modifications, additions and deletions may be made to the structures and methods recited above and shown in the drawings without departing from the scope or spirit of the invention and the following claims.