GB2617413A - Hydrogen recirculation venturi array for optimized H2 utilization against an aviation flight profile - Google Patents

Hydrogen recirculation venturi array for optimized H2 utilization against an aviation flight profile Download PDF

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Publication number
GB2617413A
GB2617413A GB2208554.2A GB202208554A GB2617413A GB 2617413 A GB2617413 A GB 2617413A GB 202208554 A GB202208554 A GB 202208554A GB 2617413 A GB2617413 A GB 2617413A
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hydrogen gas
venturis
fuel cell
valves
hydrogen
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GB2617413B (en
GB202208554D0 (en
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Lawes Stephen
Coates Gareth
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Zeroavia Ltd
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Zeroavia Ltd
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Publication of GB202208554D0 publication Critical patent/GB202208554D0/en
Priority to PCT/US2023/025071 priority patent/WO2024054277A2/en
Publication of GB2617413A publication Critical patent/GB2617413A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04082—Arrangements for control of reactant parameters, e.g. pressure or concentration
    • H01M8/04089—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants
    • H01M8/04097—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants with recycling of the reactants
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04F—PUMPING OF FLUID BY DIRECT CONTACT OF ANOTHER FLUID OR BY USING INERTIA OF FLUID TO BE PUMPED; SIPHONS
    • F04F5/00—Jet pumps, i.e. devices in which flow is induced by pressure drop caused by velocity of another fluid flow
    • F04F5/14—Jet pumps, i.e. devices in which flow is induced by pressure drop caused by velocity of another fluid flow the inducing fluid being elastic fluid
    • F04F5/16—Jet pumps, i.e. devices in which flow is induced by pressure drop caused by velocity of another fluid flow the inducing fluid being elastic fluid displacing elastic fluids
    • F04F5/20—Jet pumps, i.e. devices in which flow is induced by pressure drop caused by velocity of another fluid flow the inducing fluid being elastic fluid displacing elastic fluids for evacuating
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04F—PUMPING OF FLUID BY DIRECT CONTACT OF ANOTHER FLUID OR BY USING INERTIA OF FLUID TO BE PUMPED; SIPHONS
    • F04F5/00—Jet pumps, i.e. devices in which flow is induced by pressure drop caused by velocity of another fluid flow
    • F04F5/44—Component parts, details, or accessories not provided for in, or of interest apart from, groups F04F5/02 - F04F5/42
    • F04F5/46—Arrangements of nozzles
    • F04F5/466—Arrangements of nozzles with a plurality of nozzles arranged in parallel
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04F—PUMPING OF FLUID BY DIRECT CONTACT OF ANOTHER FLUID OR BY USING INERTIA OF FLUID TO BE PUMPED; SIPHONS
    • F04F5/00—Jet pumps, i.e. devices in which flow is induced by pressure drop caused by velocity of another fluid flow
    • F04F5/44—Component parts, details, or accessories not provided for in, or of interest apart from, groups F04F5/02 - F04F5/42
    • F04F5/48—Control
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04F—PUMPING OF FLUID BY DIRECT CONTACT OF ANOTHER FLUID OR BY USING INERTIA OF FLUID TO BE PUMPED; SIPHONS
    • F04F5/00—Jet pumps, i.e. devices in which flow is induced by pressure drop caused by velocity of another fluid flow
    • F04F5/44—Component parts, details, or accessories not provided for in, or of interest apart from, groups F04F5/02 - F04F5/42
    • F04F5/48—Control
    • F04F5/52—Control of evacuating pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04F—PUMPING OF FLUID BY DIRECT CONTACT OF ANOTHER FLUID OR BY USING INERTIA OF FLUID TO BE PUMPED; SIPHONS
    • F04F5/00—Jet pumps, i.e. devices in which flow is induced by pressure drop caused by velocity of another fluid flow
    • F04F5/54—Installations characterised by use of jet pumps, e.g. combinations of two or more jet pumps of different type
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04082—Arrangements for control of reactant parameters, e.g. pressure or concentration
    • H01M8/04089—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants
    • H01M8/04104—Regulation of differential pressures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
    • H01M8/04694—Processes for controlling fuel cells or fuel cell systems characterised by variables to be controlled
    • H01M8/04746—Pressure; Flow
    • H01M8/04753—Pressure; Flow of fuel cell reactants
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
    • H01M8/04694—Processes for controlling fuel cells or fuel cell systems characterised by variables to be controlled
    • H01M8/04746—Pressure; Flow
    • H01M8/04761—Pressure; Flow of fuel cell exhausts
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2250/00—Fuel cells for particular applications; Specific features of fuel cell system
    • H01M2250/20—Fuel cells in motive systems, e.g. vehicle, ship, plane

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  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Sustainable Energy (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Fluid Mechanics (AREA)
  • Physics & Mathematics (AREA)
  • Electric Propulsion And Braking For Vehicles (AREA)
  • Fuel Cell (AREA)

Abstract

A hydrogen gas recirculation system for a hydrogen fuel cell 60 includes (a) a plurality of venturis 52A-C, and (b) one or more valves 54A-C configured to control flow of hydrogen gas to the plurality of venturis, wherein the one or more valves are configured to selectively open and close to optimize flow of the hydrogen gas through the venturis to a speed below the speed of sound and above the spread where venturi icing occurs. The system preferably includes a digital controller 56 for controlling opening and closing of the valve(s). The system is used with a fuel cell, especially a fuel cell used to power aircraft. The selective opening and closes allows for higher or lower hydrogen flow into the fuel cell, depending on the stage of flying, i.e. take-off, cruising and landing. The venturi devices are preferably connected in parallel.

Description

HYDROGEN RECIRCULATION VENTURI ARRAY FOR OPTIMIZED H2 UTILIZATION AGAINST AN AVIATION FLIGHT PROFILE
Technical Field
The present disclosure relates integrated hydrogen fuel cell electric engine systems. The disclosure has particular utility to hydrogen fuel cell electric engines for use with transport vehicles including air craft and will be described in connection with such utility, although other utilities are contemplated.
Background and Summary
Exhaust emissions from transport vehicles are a significant contributor to climate change.
Conventional fossil fuel powered terrestrial transport vehicles, water craft and aircraft release CO2 emissions. Also conventional fossil fuel powered aircraft emissions include non-0O2 effects due to nitrogen oxide (N0x), vapor trails and cloud formation triggered by the altitude at which aircraft operate. These non-0O2 effects are believed to contribute twice as much to global warming as aircraft CO2 and were estimated to be responsible for two thirds of aviation's climate impact.
Rechargeable battery powered terrestrial vehicles, i.e., "EVs" are slowly replacing conventional fossil fuel powered terrestrial vehicles. However, the weight of batteries and limited energy storage of batteries makes rechargeable battery powered aircraft generally impractical.
Hydrogen fuel cells offer an attractive alternative to fossil fuel burning engines.
Hydrogen fuel cell tanks may be quickly filled and store significant energy, and other than the relatively small amount of unreacted hydrogen gas, the exhaust from hydrogen fuel cells comprises only water.
A fuel cell is an electrochemical device that converts chemical energy produced by a reaction directly into electrical energy. A typical hydrogen fuel cell includes a polymer electrolyte membrane (PEM), often called a proton exchange membrane, that permits only protons to pass between an anode and a cathode of the fuel cell. At the anode, diatomic hydrogen (a fuel) is reacted to produce hydrogen protons that pass through the PEM. The electrons produced by this reaction travel through circuitry that is external to the fuel cell to form an electrical current. At the cathode, oxygen is reduced and reacts with the hydrogen protons to form water. The anodic and cathodic reactions are described by the following equations: H2 4 21-P-F2e-at the anode of the cell, and Equation I 02-fr4H++4e 42H20 at the cathode of the cell. Equation 2 Referring to Fig. 1, a typical hydrogen fuel cell 10 comprises a housing 12 containing an anode 14, and a cathode I 6 sandwiching a proton exchange membrane I 8. A hydrogen fuel inlet 20 and a hydrogen recycling outlet 22 are provided on the anode side of the housing 12. An oxygen inlet 24 and a reaction product, i.e., water outlet 26 are provided on the cathode side of the housing 10. The anode side and cathode side of the membrane 18 are coated with suitable reaction catalysts 19A, 19B.
Located in the hydrogen fuel inlet 20 is a hydrogen gas injector 28 which includes a venturi nozzle 30 having a hydrogen gas recirculation inlet 32 for drawing unconsumed gaseous hydrogen back to the hydrogen fuel inlet supply.
Anodic reaction according to Equation I as described above occurs at the anode side of the cell, while a cathodic reaction as described in Equation 2 occurs at the cathode side of the cell providing a flow of electricity 28.
Venturis are widely used passive devices that utilize restriction within the flow path to vary the flow characteristics of a fluid. As the geometry increases the fluid's velocity there is a corresponding drop in pressure. This negative pressure can then be used to draw a secondary fluid into the primary flow. In fuel cells the negative pressure is used to assist with the process of hydrogen recirculation, drawing unconsumed hydrogen from the fuel cell exhaust back around into the inlet supply. Passive recirculation venturis (as opposed to active pumps) are a widely used with existing fuel cell systems.
When designing the internal injection nozzle within the venturi several things must be considered including: * The jet speed of the primary media should be as high as possible to generate the greatest delta pressure and provide the greatest recirculation suction; and * One must consider the greatest mass flow required by the system, and design the internal nozzle so that the primary media velocity is subsonic. Greater than Mach 1 turbulent flow of the primary media can occur, reducing suction and potentially generating ice crystals within some media types, leading to potential blockages.
In the case of a hydrogen fuel cell powered aircraft, maximum hydrogen gas flow requirement is at take-off, where, for example, hydrogen fuel cell stack architecture might consume in the region of around 9 grams/sec @ 600 A. This maximum hydrogen gas flow requirement only exists during the period of take-off, and as such the turn-down in suction that the venturi will experience when the fuel cell system is pulled back to minimum cruise power for example, (circa 270 A) will be significantly reduced. Conversely, designing for lower cruise limit requirements (270 A) is not practical, since the higher flow rate take-off point will violate the requirement described above of maintaining the velocity of the primary media to subsonic.
Therefore a single fixed geometry venturi cannot be designed for all duty cycle operating conditions.
In order to overcome the aforesaid and other problems of the prior art, we provide a hydrogen fuel cell system hydrogen gas inlet which includes a hydrogen gas recirculation comprising: a) a plurality of venturis, and h) one or more valves configured to control flow of hydrogen gas to the plurality of venturis, wherein the one or more valves are configured to selectively open and close to control flow of the hydrogen gas through the venturis to a speed below the speed of sound, i.e., subsonic, and above the speed where venturi icing occurs.
In one embodiment the hydrogen gas recirculation system includes a digital controller configured to control the selective opening and closing of the one or more valves. In such embodiment the venturis may include a mechanical linkage connecting throttle plates venturis to one another.
In another embodiment the plurality of venturis may be similarly sized. Alternatively the plurality of venturis may be sized differently from one another. When the plurality of venturi are sized differently from one another, in a preferred embodiment the plurality of differently sized venturis may be configured to open in sequence from smaller to larger, and vice versa.
In yet another embodiment, the valves comprise proportional valves.
In still yet another embodiment, the plurality of venturis are connected in parallel.
In still yet another embodiment the hydrogen gas recirculating system also includes a water separator upstream of the recirculating hydrogen gas. In such embodiment the water separator preferably comprises a cyclonic water separator.
The present disclosure also provides a hydrogen fuel cell system including a hydrogen gas recirculation system as above described, and including a) a plurality of venturis, and b) one or more valves configured to control flow of hydrogen gas to the plurality of venturis, wherein the one or more valves are configured to selectively open and close to optimize flow of the hydrogen gas through the venturis to a speed below the speed of sound, i.e., subsonic and above the spread where venturi icing occurs.
in still yet another embodiment there is provided a hydrogen fuel cell powered aircraft comprising at least one electric motor, and a hydrogen fuel cell system comprising a plurality of venturis as above described, and hydrogen gas recirculation system.
The present disclosure also provides a method for operating the hydrogen gas fuel cell system powered aircraft through the stages of take-off and climb, cruise, and descent and landing, wherein the hydrogen fuel cell system includes a hydrogen fuel cell including a hydrogen gas recirculation system as above described, and including a plurality of venturis, and one or more valves configured to control flow of hydrogen gas to the plurality of venturis comprising controlling the venturis to optimize hydrogen gas flow during take-off and climb, to a speed below the speed of sound and above the speed where venturi icing occurs, reduce hydrogen gas flow during cruise, and further reduce hydrogen gas flow during descent and landing.
In accordance with one aspect of the method the one or more of the plurality of valves are selectively opened or closed to provide a desired hydrogen gas flow.
In still yet another aspect of the disclosure the one or more valves are selectively proportionally opened or closed.
In still another aspect of the disclosure the plurality of venturis are sized differently from one another, and the valves associated with the plurality of venturis are sequentially opened and closed from smaller to larger and vice versa.
According to a first aspect of the present invention there is provided a hydrogen gas recirculation system for a hydrogen fuel cell comprising: a) a plurality of venturis, and h) one or more valves configured to control flow of hydrogen gas to the plurality of venturis, wherein the one or more valves are configured to selectively open and close to optimize flow of the hydrogen gas through the venturis to a speed below the speed of sound and above the spread where venturi icing occurs.
Preferably the hydrogen gas recirculation system further includes a digital controller configured to control the selective opening of the one or more valves.
Preferably the hydrogen gas recirculation system further includes a mechanical linkage connecting throttle plates of the valves to one another.
In one alternative the plurality of venturis are similarly sized.
In one alternative the plurality of venturis are sized differently from one another. Preferably the plurality of differently sized venturis are configured to open in sequence from smaller to larger, and vice versa.
Preferably the valves comprise proportional valves.
According to a second aspect of the present invention there is provide a hydrogen fuel cell system, comprising a hydrogen gas recirculation system as set out in the first aspect of the invention.
Preferably the plurality of venturis are connected in parallel.
Preferably the hydrogen fuel cell system further comprises a water separator upstream of the recirculating hydrogen gas.
Preferably the water separator comprises a cyclonic water separator.
According to a third aspect of the present invention there is provided a hydrogen fuel cell powered aircraft comprising at least one electric motor, and a hydrogen fuel cell system as set out in the second aspect of the invention.
According to a fourth aspect of the present invention there is provided a method for operating the hydrogen gas fuel cell powered aircraft of the third aspect of the invention, through the stages of take-off and climb, cruise, and descent and landing, comprising controlling the valves to maximize hydrogen gas flow during take-off and climb, reducing hydrogen gas flow during cruise, and further reducing hydrogen gas flow during descent and landing.
Preferably one or more of the plurality of valves are opened or closed to provide a desired hydrogen gas flow.
Preferably the one or more valves are proportionally opened or closed.
Preferably the plurality of venturis are sized differently from one another, and wherein the valves associated with the plurality of venturis are sequentially opened and closed from smaller to larger and vice versa.
Brief Description of the Drawings
Further features and advantages of the present disclosure will be seen from the following detailed description, taken in conjunction with the accompanying drawings, wherein like numerals depict like parts, and wherein: Fig, 1 is a cross sectional view depicting a conventional prior art fuel cell; Fig. 2 maps an aviation duty cycle from ground warming, taxi, take-off, climbing, cruising, descent and landing; Fig. 3 maps powered requiring to hydrogen fuel requirements relative to duty cycle; Fig. 4 schematically illustrates a switchable hydrogen gas venturi array in accordance
with a first embodiment of the present disclosure;
Figs. 5 and 6 are views similar to Fig. 4 of alternative embodiments of switchable hydrogen gas venturi arrays in accordance with the present disclosure; Fig. 7 is a schematic view of a gas hydrogen gas fuel cell system in accordance with the present disclosure; Figs. 8A-8C illustrate activation of one, two and three venturis in accordance with the
present disclosure;
Figs. 9A-9C are graphs of hydrogen gas flow corresponding to activation of one, two and three venturis as illustrated in Figs. 8A-8C; and Fig. 10 is a schematic view of a hydrogen gas fuel cell powered airplane having a hydrogen gas recirculation system in accordance with the present disclosure.
Detailed Description
Embodiments of the disclosure will now he described with reference to the accompanying drawings.
Given the relatively consistent nature of aviation duty cycles, it is possible to define flight power requirements. Fig. 2 maps flight power requirement from ground warming, taxi, take-off, climbing, cruise, descent and landing. These power requirements can then be mapped to hydrogen fuel consumption requirements as shown in Fig. 3.
One of the requirements of hydrogen gas fuel management systems is to control the anode inlet pressure to be above that of the cathode inlet pressure. This is achieved by measuring the inlet pressure of the hydrogen into the fuel cell stack, and then electronically modifying the flow rate to achieve the required pressure. The purpose of this requirement is to ensure that the internal membrane electrode assembly and gaskets within the stack's cells are not disproportionately stressed having variable air pressure on one side and delivered hydrogen pressure on the other, with the bias always mandating the anode pressure to be above that of the cathode pressure (for cross-over air degradation requirements). The hardware responsible for controlling this flow/pressure also determines the available mass flow to be pushed through the venturi. Thus, in the case of terrestrial vehicles such as automobiles, a single venturi may be sufficient to provide the fuel flow rate required for all stages of operation. And, while a single venturi device might he sufficient to provide the fuel for a plane's constant cruise requirements, a single venturi device would not provide the flow rate required for a plane's take-off and climbing requirements.
Combining all these considerations together; the availability of pre-validated fuel cell system pressure controllers, the need to size the venturi for constant cruise power, the issue of turn-down suction when sized for take-off, the significant weight/volume savings of using a venturi, and the fact a venturi is a passive device, in accordance with the present disclosure, we provide a hydrogen fuel cell system including an array of switchable venturis. Referring to Fig. 4, in a first embodiment, we provide an array 50 of three switchable venturis 52A, 52B, 52C, which collectively have a capacity for the consumption duty cycle anticipated within the aviation application from warm up and taxi, take-off and climbing, cruising, descent and landing. More particularly, venturis 52A, 52B and 52C each have an associated valve actuator 54A, 54B, 54C respectively which are controlled by a controller 56. Valves 54A, 54B, 54C all are connected to a common hydrogen gas supply 58. Venturis 52A, 52B, 52C are connected in parallel to a common hydrogen fuel cell stack inlet 60. Venturis 52A, 52B, 52C each preferably also include hydrogen gas recirculation inlets 62A, 62B, 62C. Alternatively, it is sufficient to provide a hydrogen gas recirculation inlet to fewer than all three venturis 52A, 52B, 52C. As shown in Fig. 4, venturis 52A, 52B and 52C are all the same size. Mechanical linkages 70 may be provided connecting the throttle plates of the three venturis 52A, 52B, 52C, so that the three venturis open and close in sequence, under control of controller 56.
Alternatively, as shown in Fig. 5, the venturis 64A, 64B and 64C may be differently sized, and may be configured to open and close from smaller to larger, or vice versa.
Referring to Fig. 6, in yet another embodiment the array may include proportional valves 80A, 80B, 80C which can he controlled to allow lower flow through the venturis 82A, 82B, 82C during start-up, taxing and descent.
Fig. 7 illustrates in more detail, a hydrogen gas fuel cell system 100 in accordance with the present disclosure, including a fuel cell 102 having an anode 104, a cathode 106 and proton exchange membrane 108. Cell 102 includes a hydrogen gas inlet 110 and a hydrogen gas recycling outlet 112 at the anode 104, and an oxygen gas inlet 113, and a water outlet 116 at the cathode 106. An array 120 of three venturis 122A, 122B, 122C are connected through one way valves 124A, 124B, 124C and conduit 126 to a cyclonic water separator 128 which removes water vapor from the hydrogen gas before it is fed via inlet 110 to the fuel cell 102. Cyclonic water separator 128 also includes a valved water drain 130.
Venturis 122A, I22B, I22C are connected via flow control valves I32A, I32B, 132C to hydrogen fuel tank 134.
Since the recycled hydrogen gas from anode outlet 112 also may contain some water vapor, the recycled hydrogen is first passed through a cyclonic water separator 140. Cyclonic water separator 140 includes a valved water drain 142 and a recycle hydrogen gas outlet 144 which is connected to the recirculation inlets 146A, 146B, 146C of venturis 122A, 122B, 122C.
Operation of the entire hydrogen fuel cell system 100 is under control of controller 150.
Figs. 8A-8C illustrate activation of the one, two and three venturis 122A, 122B, 122C. Figs. 9A-9C are graphs of hydrogen gas flow corresponding to activation of one, two or three venturis, on an airplane so illustrated in Fig. 10. Airplane 80 includes two electric motors 82A, 82B which are supplied by two parallel hydrogen fuel cell systems 84A, 84B including an array of switchable venturis 86A, 86B in accordance with the present disclosure.
For take-off (600 A -9 grams/sec) three venturis will be enabled.
For maximum cruise (440 A -6 grams/sec) two venturis will be enabled, the third venturi will be disabled and have zero flow. In this case the two active venturis will receive 3 grams/sec each, 6 grams/sec total, and still provide the maximum passive recirculation suction possible, as they aren't turn-down limited.
For descent and landing, and also taxiing, a single venturi will be enabled, while the other two venturis are turned-down.
A feature and advantage of the present disclosure is given the relatively small size and weight of valve and venting components adding a third venturi also provides a redundancy stream, should either of the other venturi have issues. Another feature and advantage of the present disclosure is the active order of venturi feed streams can be cycled over life, spreading any potential component wear across the array of valves and venturis and improving mean time between failures. For example, the cruise stream will see the most active service, but over time the valves and venturis used to form the cruise stream can be changed to other streams in the array, so the activity load is spread.
Table!below provides illustrative values of hydrogen gas flow in accordance with the present disclosure.
18 08 22
Table 1
Honddified Hydrogen042) HumidedHydrogen04A Humidified Ow (Hj Haddified Hydrogen (142 HSdifled Hydrogen (RA HuffdthfiedHythogen (HA Sudan Cgs liole0990 Wert vove.opor Fla:9 Rate On,fir -'no9kOoi /dgc.mi 75,mrorfttorodiv,,, opuniom 3,,i,n1;:efi4re dog premre. osg CURRENT IA) Moo/titreGoo Hydrogen IHJ Orogen (Hz) Hydrogen (fij.
Hrdwen(fY ?Orem Pre59.9retno be (ur onafthed&re presmo target, Mc Max. Liae premre (pqj Onecgio M.(stive pre:,st:at rag Tem oeram dee may.. 70.6
0 to 63$ poi9 15A 154N 70.06 /9.09 6,W 15A 9. 704)9 0.20 9.49 70.90 05.09
65.0, 05.09, 6.0 9 19 1167

Claims (16)

  1. What is Claimed: I. A hydrogen gas recirculation system for a hydrogen fuel cell comprising: a) a plurality of venturis, and b) one or more valves configured to control flow of hydrogen gas to the plurality of venturis, wherein the one or more valves are configured to selectively open and close to optimize flow of the hydrogen gas through the venturis to a speed below the speed of sound and above the spread where venturi icing occurs.
  2. 2. The hydrogen gas recirculation system of claim 1, further including a digital controller configured to control the selective opening of the one or more valves.
  3. 3. The hydrogen gas recirculation system of claim 1 or claim 2, further including a mechanical linkage connecting throttle plates of the valves to one another.
  4. 4. The hydrogen gas recirculation system of any preceding claim, wherein the plurality of venturis are similarly sized.
  5. 5. The hydrogen gas recirculation system of any of claims I to 3, wherein the plurality of venturis are sized differently from one another.
  6. 6. The hydrogen gas recirculation system of claim 5, wherein the plurality of differently sized venturis are configured to open in sequence from smaller to larger, and vice versa.
  7. 7. The hydrogen gas recirculation system of any preceding claim, wherein the valves comprise proportional valves.
  8. 8. A hydrogen fuel cell system, comprising a hydrogen gas recirculation system as claimed in any of claims 1 to 7.
  9. 9. The hydrogen gas fuel cell system of claim 8, wherein the plurality of venturis are connected in parallel.
  10. 10. The hydrogen fuel cell system of claim 8 or claim 9, further comprising a water separator upstream of the recirculating hydrogen gas.
  11. 11. The hydrogen fuel cell system of claim 10, wherein the water separator comprises a cyclonic water separator.
  12. 12. A hydrogen fuel cell powered aircraft comprising at least one electric motor, and a hydrogen fuel cell system as claimed in any of claims 8 to 11.
  13. 13. A method for operating the hydrogen gas fuel cell powered aircraft of claim 12, through the stages of take-off and climb, cruise, and descent and landing, comprising controlling the valves to maximize hydrogen gas flow during take-off and climb, reducing hydrogen gas flow during cruise, and further reducing hydrogen gas flow during descent and landing.
  14. 14. The method of claim 13, wherein one or more of the plurality of valves are opened or closed to provide a desired hydrogen gas flow.
  15. 15. The method of claim 14, wherein the one or more valves are proportionally opened or closed.
  16. 16. The method of any of claims 13 to 15, wherein the plurality of venturis are sized differently from one another, and wherein the valves associated with the plurality of venturis are sequentially opened and closed from smaller to larger and vice versa.
GB2208554.2A 2022-06-10 2022-06-10 Hydrogen fuel cell powered aircraft Active GB2617413B (en)

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PCT/US2023/025071 WO2024054277A2 (en) 2022-06-10 2023-06-12 Hydrogen fuel-cell systems

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