Embodiments of the present invention relate generally to oxygen/air supply systems and methods for use with fuel cell system applications on-board passenger transportation vehicles, such as aircraft or other aerospace vehicles, ground vehicles, or stationary applications for which oxygen and/or air has to be supplied to the fuel cell system.
Current fuel cell systems are generally fed with pure oxygen (100% of O2) or air (˜21% of O2). The fuel cell system efficiency depends on the Membrane Electrode Assembly (polarization curve) and cathode supply fluids (Oxygen or air). A fuel cell stack device converts chemical energy from a fuel into electricity through an electrochemical reaction with an oxidizer (oxygen). It is common to use the oxygen contained in air (˜21%) or other oxygen sources. As fuel, Hydrogen is used in most of the common fuel cell systems.
Fuel cells differ from batteries in that they require a supply of fuel and oxidant to operate, but they can produce electricity continuously for as long as these inputs are supplied. The energy efficiency of a fuel cell to produce electricity is typically between 50-70%. Additionally, the higher the concentration of oxygen (oxygen >21%), the better the fuel cell efficiency is. Fuel cell systems are not always optimized between the storage Weight/Volume ratio and the % O2/FCS (fuel cell system) efficiency ratio. A tradeoff must thus be performed between these ratios depending on the fuel cell and its field of application.
In the aerospace field, the current power generation options (ground power unit, auxiliary power unit, and engines) produce noise and CO2 emissions as their by-products, and require fossil fuels for operation. By contrast, fuel cell systems produce water and nitrogen (Oxygen Depleted Air) as their by-products.
A number of components on-board an aircraft require electrical power for their activation. Many of these components are separate from the electrical components that are actually required to run the aircraft (i.e., the navigation system, fuel gauges, flight controls, and hydraulic systems). For example, aircraft also have catering equipment, heating/cooling systems, lavatories, power seats, water heaters, and other components that require power as well. Specific components that may require external power include but are not limited to trash compactors (in galley and/or lavatory), ovens and warming compartments (e.g., steam ovens, convection ovens, bun warmers), optional dish washer, freezer, refrigerator, coffee and espresso makers, water heaters (for tea), air chillers and chilled compartments, galley waste disposal, heated or cooled bar carts/trolleys, surface cleaning, area heaters, cabin ventilation, independent ventilation, area or spot lights (e.g., cabin lights and/or reading lights for passenger seats), water supply, water line heating to prevent freezing, charging stations for passenger electronics, electrical sockets, vacuum generators, vacuum toilet assemblies, grey water interface valves, power seats (e.g., especially for business or first class seats), passenger entertainment units, emergency lighting, and combinations thereof. These components are important for passenger comfort and satisfaction, and many components are absolute necessities.
However, one concern with these components is their energy consumption. As discussed, galley systems for heating and cooling are among several other systems aboard the craft which simultaneously require power. Frequently, such systems require more power than can be drawn from the aircraft engines' drive generators, necessitating additional power sources, such as a kerosene-burning auxiliary power unit (APU) (or by a ground power unit if the aircraft is not yet in flight). This power consumption can be rather large, particularly for long flights with hundreds of passengers. Additionally, use of aircraft power produces noise and CO2 emissions, both of which are desirably reduced. Accordingly, it is desirable to identify ways to improve fuel efficiency and power management by providing innovative ways to power these components. There are new ways being developed to generate power to run on-board components, as well as to harness beneficial by-products of that power generation for other uses on-board passenger transport vehicles, such as 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 it is beneficial to utilize these outputs as well. 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 CO2 emissions from current aircraft power generation processes.
Embodiments of the invention described herein thus provide an autonomous Fuel Cell System with an optimized efficiency to weight and volume ratio by virtue of its having an innovative cathode supply system generating air, Oxygen Enriched Air, or pure oxygen (O2).
The embodiments described herein are useful with any types of fuel cell systems, including but not limited to PEMFC or PEM (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. Although they are described with particular emphasis for use on aircraft and other aerospsace vehicles, the systems and methods described herein may be useful on other passenger transport vehicles, as well as other fuel cell systems that are stationary.
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It should be understood that each of the systems and embodiments shown and described may be used alone or in combination with any of the other described embodiments. The primary goal is to provide an optimized way to provide and deliver air/oxygen to the fuel cell system 5 with the desired weight and volume ratio. This provides an autonomous fuel cell system that has a hydrogen source as well as an oxygen enriched air or pure oxygen source.
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.
This application claims the benefit of U.S. Provisional Application Ser. No. 61/620,517, filed Apr. 5, 2013, titled “Oxygen/Air Supply For Fuel Cell Applications,” the entire contents of which are hereby incorporated by reference.
Filing Document | Filing Date | Country | Kind |
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PCT/US2013/030634 | 3/13/2013 | WO | 00 |
Number | Date | Country | |
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61620517 | Apr 2012 | US |