GB2545001A

GB2545001A - Inlet assembly

Info

Publication number: GB2545001A
Application number: GB1521337.4A
Authority: GB
Inventors: Kupcho Kevin
Original assignee: Intelligent Energy Ltd
Current assignee: Intelligent Energy Ltd
Priority date: 2015-12-03
Filing date: 2015-12-03
Publication date: 2017-06-07
Anticipated expiration: 2035-12-03
Also published as: GB2545001B; GB201521337D0

Abstract

An inlet assembly 1 for a fuel cell comprises a duct 5 comprising inlet and outlet ends 6, 7 for receiving a flow of gas therebetween along a flow path 8 through the duct and an inlet conduit 10 extending through a wall of the duct comprising a mouth 12 configured to receive the gas from within the duct, wherein the mouth is arranged perpendicularly to the flow path and includes open cell foam (20, figure 4). The mouth may include a lattice (40) comprising holes and supporting ribs, with the foam configured to abut the lattice and may also include one or more louvres arranged to divert gas flowing through the duct. Also disclosed is a thrust device comprising said inlet assembly and a thrust providing element 3, preferably a fan, mounted within the duct. A fuel cell powered thrust device comprises said thrust device and one or more fuel cells mounted around the duct and connected to the inlet conduit to receive a supply of air at the cathode of the one or more fuel cells.

Description

INLET ASSEMBLY

This invention relates to an inlet assembly, such as an air inlet assembly. In particular, it relates to an air inlet assembly for a fuel cell wherein the air inlet is arranged in a wall of a duct. The invention also relates to a fuel cell powered thrust device including the air inlet assembly. The invention also relates to a fuel cell network including the air inlet assembly.

Conventional electrochemical fuel cells convert fuel and oxidant into electrical energy and a reaction product. A common type of electrochemical fuel cell comprises a membrane electrode assembly (MEA), which includes a polymeric ion (proton) transfer membrane between an anode and a cathode and gas diffusion structures. The fuel, such as hydrogen, and the oxidant, such as oxygen from air, are passed over respective sides of the MEA to generate electrical energy and water as the reaction product. A stack may be formed comprising a number of such fuel cells arranged with separate anode and cathode fluid flow paths. Such a stack is typically in the form of a block comprising numerous individual fuel cell plates held together by end plates at either end of the stack. Air may be delivered to the cathode gas diffusion structures through an air manifold.

Fuel cells may be used to provide energy for use in the propulsion of vehicles, such as aircraft or land-based or water-based vehicles. In certain applications, power is provided for propulsion using a thrust device, which generates the motive power by acceleration of air, such as by way of a fan or turbine engine. The propulsion air may be directed along a duct or nozzle for directing the propulsive force.

According to a first aspect of the invention we provide an inlet assembly for a fuel cell comprising; a duct comprising an inlet end and an outlet end and configured to receive a flow of gas between the inlet end and the outlet end along a flow path through the duct; an inlet conduit for receiving at least part of the flow of gas to supply to a fuel cell, the inlet conduit extending through a wall of the duct and having a mouth configured to receive the gas from within the duct, the mouth arranged substantially perpendicular to the flow path and wherein the mouth includes an open cell foam configured to receive therethrough a flow of the gas from the duct for supply to the fuel cell.

Thus, the duct may provide for flow of a high velocity gas flow and the inlet conduit being perpendicular to said flow and including open cell foam has been found to provide an advantageous inlet assembly in terms of flow rate reduction from the duct gas and/or uniform pressure distribution. Further, it has been found that given the mouth is substantially perpendicular to the flow through the duct, the flow of gas through the duct may pass across a surface of the open cell foam rather than substantially impinging onto it. This may allow the inlet assembly to receive gas substantially from an outer edge of the flow of gas, which may provide an advantageous flow distribution and flow rate into the inlet assembly.

The flow of gas through the duct may provide thrust for a thrust powered device. In other examples the flow of gas may provide for supply of gas to a plurality of fuel cells along the duct, each fuel cell (either planar or of fuel cell stack configuration) receiving the gas as a reactant from the duct, which is common to each of the inlet assemblies. It will be appreciated that the inlet assembly may have application in other situations in which a gas flow for supply to a fuel cell is received from a duct that carries a through-flow of the gas.

In one or more examples, the inlet assembly comprises an air inlet assembly and the duct is configured to receive a flow of air. The air inlet assembly may be configured to receive the air from the flow of air through the duct for supply to a cathode of a fuel cell.

In one or more examples, the open cell foam substantially fills the mouth of the inlet conduit. The open cell foam may be advantageous for receiving gas from the high velocity flow through the duct. In other examples, the open cell foam may comprise a plurality of sections separated by other material such as supports or lattice or other porous material.

In one or more examples, the open cell foam includes an inlet face configured perpendicular to the flow path. The inlet face may be substantially flat and/or free from projections.

In one or more examples, the inlet face is substantially flush with an interior surface of the duct.

In one or more examples, the mouth includes a lattice comprising holes and supports or ribs and the open cell foam is configured to abut the lattice.

In one or more examples, the open cell foam is substantially unsupported across its inlet face other than at one or more peripheral edges thereof.

In one or more examples, the open cell foam comprises a first major side and a second major side opposed to the first major side, the first and second major sides connected by one or more side walls which together define the volume of the open cell foam, wherein the first major side comprises the inlet face. Thus, the mouth may allow for receipt of gas from the duct over the majority or substantially all of the first major side.

In one or more examples, the mouth includes one or more louvres configured to divert the gas flowing through the duct towards the open cell foam. In one or more examples, the mouth is absent of louvers or other such structures for diverting the gas from the flow path through the duct towards the open cell foam.

In one or more examples, the duct is substantially cylindrical and the mouth extends circumferentially around at least part of the cylindrical duct.

In one or more examples, the open cell foam has a porosity of at least 40 pores per linear inch (15.7 pores per cm) or at least 50 pores per linear inch (19.7 pores per cm). In one or more examples, the open cell foam has a porosity of less than 150 pores per linear inch (59.1 pores per cm) or less than 120 pores per linear inch (47.2 pores per cm). The measure of porosity may be determined using an ASTM-D3576 test method or based on manufacturer specified values.

In one or more examples, the inlet conduit includes a fuel cell end at an end opposed to the mouth configured to connect to the cathode(s) or cathode manifold of a fuel cell/fuel cell stack. In one or more examples, the duct is configured to receive the fuel cell for mounting to an outer surface thereof.

In one or more examples, the mouth comprises a slit arranged at an upstream end of the open cell foam, with respect to the flow of gas. In one or more examples, the fuel cell end of the inlet conduit is open across the majority of the second major surface of the open cell foam. In one or more examples, the first major surface of the open cell foam is covered except for the slit. In one or more examples, a plurality of slits are provided.

According to a second aspect of the invention we provide a thrust device comprising the inlet assembly of the first aspect having a thrust providing element, such as a fan, mounted within the duct, and wherein the mouth is arranged at least partially downstream of the thrust providing element.

In one or more examples, the mouth is arranged entirely downstream of the fan.

According to a third aspect of the invention we provide a fuel cell powered thrust device comprising the thrust device of the second aspect having one or more fuel cells mounted around the duct, the one or more fuel cells comprising an anode configured to receive a flow of fuel and a cathode configured to receive a supply of oxidant for providing electrical power, the one or more fuel cells connected to the inlet conduit to receive a supply of gas, as a reactant, at an active area (such as a cathode/anode) of the one or more fuel cells, the one or more fuel cells configured to provide, at least in part, said electrical power to the thrust providing element.

In some examples, the fuel cells provide at least the majority of the electrical power for powering the thrust providing element.

According to a further aspect of the invention we provide a fuel cell network comprising a plurality of fuel cells each associated with an inlet assembly of the first aspect, the duct of each inlet assembly comprising a common gas supply duct common to each of the inlet assemblies and configured to provide the gas, as a reactant, to each of the fuel cells.

There now follows, by way of example only, a detailed description of embodiments of the invention with reference to the following figures, in which:

Figure 1 shows an example thrust device including an inlet assembly, a fuel cell and a thrust providing element;

Figure 2 shows a first example inlet assembly and fuel cell;

Figure 3 shows perspective view of the duct of the example of Figure 2;

Figure 4 shows a second example inlet assembly and fuel cell;

Figure 5 shows a plan view of an example lattice shown in Figure 4; and

Figure 6 shows a third example inlet assembly.

Figure 1 shows an inlet assembly 1 for a fuel cell 2. In this example and the further examples below the inlet assembly 1 comprises an air inlet assembly, although it will be appreciated that other gases may be received thereby. The fuel cell 2 is configured to provide electrical power for driving a thrust providing element 3. In this example, the fuel cell 2 comprises a plurality of fuel cells arranged in a stack and the air inlet assembly 1 is configured to deliver air to cathode channels (described below). In other examples, the air inlet assembly 1 may be configured to deliver air to a manifold, which may distribute the air to one or more of the fuel cells in the stack. The air inlet assembly 1, fuel cell 2 and thrust providing element 3 may collectively be referred to as thrust device 4. The thrust providing element 3 may provide a propulsive force directly by the exhaust of accelerated air or may provide its accelerated air to a further part that provides the thrust. Thus, the thrust providing element may act as a compressor. Further, in this example, the thrust device is configured to provide thrust for a motive application, such as providing propulsive power to an aerial vehicle (or alternatively a land- or water-based vehicle). However, in other examples, it may provide thrust for driving a turbine. The thrust generated by the thrust providing element 3 may be used in full or in part for providing propulsion. In some examples, part of the thrust generated may be used by the fuel cell, such as for cooling. It will be appreciated that the air pressure provided by the flow of accelerated air may act to drive some of said air into the air inlet assembly 1.

The duct may comprise a ducted fan housing for a ducted fan. The fuel cell may power the ducted fan. The duct may comprise an air supply duct for providing a further apparatus with a source of air. The fuel cells may be used to power fans to move air along the duct. The duct may comprise a common air supply duct for a plurality of fuel cells, the fuel cells located along the duct and configured, via respective air inlet assemblies, to receive air from the duct as an oxidant at their cathodes. Thus, the plurality of fuel cells may comprise a fuel cell power network having a common air supply duct. The air may be provided to the air supply duct by a compressor or turbo pump or the like.

The thrust providing element 3 may comprise a fan, which may be powered by electrical power from the fuel cell 2. The duct 5 may thus comprise a ducted fan housing.

The inlet assembly 1 comprises a duct 5 having an inlet end 6 and an outlet end 7 and configured to receive a flow of air or gas between the inlet end 6 and the outlet end 7 along a flow path 8 through the duct 5. The flow of air or gas may be for providing thrust. The assembly 1 further includes an inlet conduit 10 for receiving air or gas from the duct 5 to supply to the fuel cell 2. The inlet assembly 10 may supply air to the cathode of the fuel cell 2 for example. The inlet conduit 10 extends through an aperture in the wall 11 of the duct 5 and has a mouth 12 to receive the gas or air from within the duct 5. The mouth 12 is arranged perpendicular to the flow path 8; that is the mouth 12 faces a direction that is perpendicular to the flow path 8. The mouth 12 includes an open cell foam (shown in figures 2,4 and 6) configured to receive therethrough a flow of air from the duct 5 for supply to the cathode of the fuel cell 2. Thus, high velocity gas or air that flows along the flow path 8 is diverted or extracted through the perpendicular mouth 12 in the wall of the duct such as for use as the oxidant for the fuel cell. The open cell foam and the arrangement of the air inlet assembly 1 has been found to provide an advantageous flow profile through the foam, which may be particularly uniform and of appropriate flow rate/pressure for presentation to the cathode (or cathode manifold) of a fuel cell mounted to an outside surface 14 of the duct 5.

Figures 2 and 3 shows a first example of the air inlet assembly of Figure 1. Figure 2 shows the wall 11 of the duct 5 with the air inlet assembly 1 formed therein and having the mouth 12 opening into an interior 13 of the duct 5. Figure 3 shows the duct 5 without the inlet conduit 10 and the fuel cell 2. The duct 5 is, in this example, at least in part, substantially cylindrical. The duct 5 includes an arcuate aperture 30 in its wall 11, which receives the inlet conduit 10 and thus defines the mouth 12 therewith. Accordingly, the mouth 12 extends over a substantially arcuate plane complimentary to the aperture 30 and the duct 5. In other examples, the duct 5 may be of rectangular section and the aperture 30 may be planar rather than arcuate. The inlet conduit 10 may therefore comprises a saddle that mounts to the duct 5, contains the open cell foam 20 and defines an inlet flow path from the interior of the duct 5 to the fuel cell 2.

The structure and component parts of the air inlet assembly are important as the air inlet assembly may be required to slow the duct flow sufficiently for receipt by the fuel cell, present a substantially uniform flow rate/pressure across its outlet surface, particularly if providing flow to a fuel cell stack, and also provide low disruption to the flow through the duct. It will be appreciated that providing such an air inlet assembly that satisfies these factors is difficult.

Figure 2 shows open cell foam 20 mounted in the mouth 12. The open cell foam comprises a layer having a first major surface 21, a second major surface 22 opposite the first major surface and wherein the thickness of the layer defined by the distance between the first and second major surfaces 21, 22. The first major surface 21, in this example, faces the interior 13 of the duct 5. The second major surface 22, in this example, faces the fuel cell 2. Thus, air flowing through the duct, is drawn into the first major surface of the open cell foam, permeates therethrough, and flows out of the second major surface for receipt at the cathode of the fuel cell 2. The open cell foam is moulded, formed or deformed in use to sit within the mouth substantially flush with an interior surface of the wall 11. In particular, the first major surface 21 of the open cell foam 20 may define a surface that is substantially continuous with the wall 11 of the duct 5 around the aperture 30, which may reduce the disruption to the air flow along flow path 8. Thus, the open cell foam may be flush with (and/or recessed) over substantially its whole first major surface 21 relative to the interior profile of the walls of the duct 5. In some examples, the open cell foam 20, as a whole or by way of projections from the first major surface 21, may project into the interior of the duct 5. In some examples, the layer of open cell foam 20 is flush with wall 11 at least at a downstream end of the duct 5. In some examples, the layer of open cell foam 20 is flush with wall 11 at least at an upstream end of the duct 5.

The aperture 30 and thus the layer of open cell foam 20 may have an aspect in which its longest dimension across the first/second major sides, i.e. in-plane, is aligned with the flow path 8. It will be appreciated that in some examples the thickness of the open cell foam and/or its area may be selected to suit the fuel cell and/or particular application.

The open cell foam layer has a thickness of between 2 and 20 mm or less than 20 mm; between 3 and 10 mm or less than 10 mm. In this example, the thickness is about 5 mm. In this example, the open cell foam layer has a substantially uniform thickness. Further the open cell foam 20 has a porosity of between 20 and 200 pores per linear inch (ppi) (7.9 and 78.7 pores per cm), such as between 30 and 150 ppi (11.8 and 59.1 pores per cm) or between 30 and 120 ppi (11.8 and 47.2 pores per cm). In this example, the porosity is about 60 ppi (23.6 pores per cm).

The thrust providing element 3, in this example, may generate an airflow of around 33 m/s along flow path 8 with an internal static pressure of 1600 Pa. The open cell foam 20 and the arrangement of the inlet assembly 1 was found to effectively reduce the flow rate entering the intel conduit to below 2 m/s or below 1 m/s. Further, the open cell foam was found to provide a substantially uniform flow rate leaving the second major surface 22.

In this example, the layer of open cell foam is unsupported across its first major face 21 except at its peripheral edges 23. It has been found that providing for undisrupted flow along flow path 8 over the first major surface of the open cell foam allows for advantageous flow through the open cell foam.

Figure 4 shows a second example in which the aperture 30 rather than being completely open is traversed with a lattice 40. The lattice 40 is shown in section in Figure 4 and in plan view in figure 5. The lattice 40 spans the aperture 30 and is arcuate. The lattice 40 may be formed by a plurality of cut-outs in the wall 11 of the duct 5. The open cell foam layer 20 is configured to lie against the lattice 40. Thus, the first major surface 21 is supported across its face by the lattice 40.

The lattice 40 is advantageous in that it supports the open cell foam 20. Further the open cell foam 20 may be urged against the lattice to adopt its arcuate shape. It will be appreciated that the open cell foam layer may be moulded or formed to the arcuate shape. The width and/or thickness of the lattice 40 may affect the flow through the open cell foam 20. However, it has been found that the open cell foam is advantageous in that any pressure differences caused by the presence of the lattice 40 (due to turbulence and/or lack of flow in the region of the lattice) is evened out as the air flows through the open cell foam. Arrows 41 show the air from the duct flowing through gaps in the lattice and diffusing to a more uniform flow distribution by the second major side 22.

In some examples, the layer of open cell foam may be supported by very fine or thin lattice supports that have a very small impact on the air flow over the layer of open cell foam. Thus, the area of the lattice or supports relative to the area of the open cell foam layer may be less than 10%, 5%, 2%, 1%, or 0.5%.

Figure 6 shows a third example in which the aperture 30 comprises a circumferentially extending slit 60 (other shapes may be used). The slit 60 includes a louver 61 that extends from the interior wall of the duct 5 into the flow path 8. Accordingly, the louver 61 comprises an air diverting member that changes the direction of the air flowing along flow path 8 in a radially outward direction into the inlet conduit 10 and open cell foam 20. In this example, one louver 61 is provided at an upstream end relative to the positon of inlet conduit 10. In some examples, more than one louver 61 (and associated slit 60 or other shaped aperture) may be provided at spaced locations along the interface between the inlet conduit and the duct. The louver 61, in this example, extends into the flow from the wall by less than 6mm such as about 4mm.

In this example, the air from the flow path 8 is directed into a forward (upstream relative to the flow path 8) end 62 of the open cell foam 20. The air passes through the open cell foam towards a rearward end 63 (downstream relative to the flow path 8) and also out of the second major surface 22 to be received by the fuel cell, as shown by arrows 64.

The inlet conduit 10 comprises a tubular structure having a short length relative to its width. The inlet conduit 10 includes a fuel cell end 24 at an end opposed to the mouth 12 configured to connect to the cathode or a cathode manifold of a fuel cell. As mentioned above the fuel cell may comprise a plurality of fuel cells arranged as a fuel cell stack. If the fuel cell 2 is a planar fuel cell, the fuel cell end 24 may be configured to receive the fuel cell 2 such that the planar cathode lies across the open, fuel cell end 24 and thus receives the air flow therefrom from the second major surface 22 (through a filter, if necessary). If the fuel cell 2 comprises a stack of fuel cells, the fuel cell end 24 may be configured to receive the stack on its side. This may be advantageous as air from the second major surface 22 may flow directly into cathode channels 25 (through a filter, if necessary) of one or more of the fuel cells of the stack, as shown by arrows 26 in Figure 2.

The fuel cell powered thrust device 4 may include a plurality of fuel cells or fuel cell stacks mounted circumferentially around the duct 5. Thus, the flow of air from the propulsion providing element through the duct 5 or the pressure caused thereby may advantageously provide a uniform flow of oxidant, by virtue of the open cell foam, for providing the fuel cells with its required reactants. A shroud (not shown) may, in combination with the duct enclose the fuel cells.

The examples given herein primarily relate to an inlet assembly configured to receive a portion of the air from the through-flow of air through the duct. However, it will be appreciated, as mentioned above, that the flow of air may in some examples instead comprise a flow of reactant for a fuel cell (such as hydrogen or oxygen).

Claims

1. An inlet assembly for a fuel cell comprising; a duct comprising an inlet end and an outlet end and configured to receive a flow of gas between the inlet end and the outlet end along a flow path through the duct; an inlet conduit for receiving at least part of the flow of gas to supply to a fuel cell, the inlet conduit extending through a wall of the duct and having a mouth configured to receive the gas from within the duct, the mouth arranged substantially perpendicular to the flow path and wherein the mouth includes an open cell foam configured to receive therethrough a flow of the gas from the duct for supply to the fuel cell.

2. An inlet assembly according to claim 1, wherein the inlet assembly comprises an air inlet assembly and the duct is configured to receive a flow of air.

3. An inlet assembly according to claim 1 or claim 2, wherein the open cell foam substantially fills the mouth of the inlet conduit.

4. An inlet assembly according to any preceding claim, wherein the open cell foam includes an inlet face configured perpendicular to the flow path.

5. An inlet assembly according to claim 4, wherein the inlet face is substantially flush with an interior surface of the duct.

6. An inlet assembly according to any preceding claim, wherein the mouth includes a lattice comprising holes and supporting ribs and the open cell foam is configured to abut the lattice.

7. An inlet assembly according to claim 4 or 5, wherein the open cell foam is substantially unsupported across its inlet face other than at one or more peripheral edges thereof.

8. An inlet assembly according to claim 4, wherein the open cell foam comprises a first major side and a second major side opposed to the first major side, the first and second major sides connected by one or more side walls which together define the volume of the open cell foam, wherein the first major side comprises the inlet face.

9. An inlet assembly according to any of claims 1 to 6 and 8, wherein the mouth includes one or more louvres arranged to divert gas flowing through the duct towards the open cell foam.

10. An inlet assembly according to any preceding claim, wherein the duct is substantially cylindrical and the mouth extends circumferentially around at least part of the cylindrical duct.

11. An inlet assembly according to any preceding claim, wherein the open cell foam has a porosity of at least 40 pores per linear inch or at least 50 pores per linear inch (16 and 20 pores per centimetre respectively).

12. An inlet assembly according to any preceding claim, wherein the inlet conduit includes a fuel cell end at an end opposed to the mouth configured to connect to the fuel cell.

13. An inlet assembly according to any preceding claim, wherein the duct is configured to receive the fuel cell for mounting to an outer surface thereof.

14. An inlet assembly according to claim 1 or claim 2, wherein the mouth comprises a slit arranged at an upstream end of the open cell foam, with respect to the flow of gas.

15. A thrust device comprising the inlet assembly of any preceding claim having a thrust providing element, such as a fan, mounted within the duct, and wherein the mouth is arranged at least partially downstream of the thrust providing element.

16. A thrust device comprising the inlet assembly of claim 15, wherein the mouth is arranged entirely downstream of the fan.

17. A fuel cell powered thrust device comprising the thrust device of claim 15 or claim 16 having one or more fuel cells mounted around the duct, the one or more fuel cells comprising an anode configured to receive a flow of fuel and a cathode configured to receive a supply of oxidant for providing electrical power, the one or more fuel cells connected to the inlet conduit and configured to receive a supply of air, as the oxidant, at the cathode of the one or more fuel cells, the one or more fuel cells configured to provide, at least in part, said electrical power to the thrust providing element.

18. A fuel cell network comprising a plurality of fuel cells each associated with an inlet assembly of any one of claims 1 to 14, the duct of each inlet assembly comprising a common gas supply duct common to each of the inlet assemblies and configured to provide the gas, as a reactant, to each of the fuel cells.