U.S. patent application number 14/503497 was filed with the patent office on 2015-04-02 for pem fuel cell stack inlet water regulation system.
The applicant listed for this patent is GM Global Technology Operations LLC. Invention is credited to Eric J. Connor, Steven G. Goebel, James M. Keogan, Jon P. Owejan, William H. Pettit, Thomas W. Tighe, Thomas A. Trabold.
Application Number | 20150093673 14/503497 |
Document ID | / |
Family ID | 43625409 |
Filed Date | 2015-04-02 |
United States Patent
Application |
20150093673 |
Kind Code |
A1 |
Owejan; Jon P. ; et
al. |
April 2, 2015 |
PEM FUEL CELL STACK INLET WATER REGULATION SYSTEM
Abstract
A fuel cell stack assembly is disclosed that includes a porous
member disposed within a flow path for a reactant. A fluid
collection member is provided within the flow path adjacent to and
in fluid communication with the porous member. The porous member
and the fluid collection member cooperate to collect liquid water
from the reactant flowing in the flow path, wherein the collected
liquid water may be drained from the fluid collection member.
Inventors: |
Owejan; Jon P.; (Honeoye,
NY) ; Trabold; Thomas A.; (Pittsford, NY) ;
Pettit; William H.; (Rochester, NY) ; Tighe; Thomas
W.; (Bloomfield, NY) ; Keogan; James M.;
(Lima, OH) ; Connor; Eric J.; (Rochester, NY)
; Goebel; Steven G.; (Victor, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GM Global Technology Operations LLC |
Detroit |
MI |
US |
|
|
Family ID: |
43625409 |
Appl. No.: |
14/503497 |
Filed: |
October 1, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12551600 |
Sep 1, 2009 |
8877392 |
|
|
14503497 |
|
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|
Current U.S.
Class: |
429/450 |
Current CPC
Class: |
H01M 8/04156 20130101;
H01M 8/04171 20130101; H01M 8/04253 20130101; H01M 8/242 20130101;
H01M 8/0271 20130101; H01M 8/2485 20130101; H01M 2300/0082
20130101; Y02E 60/50 20130101; H01M 2008/1095 20130101; H01M
8/04291 20130101 |
Class at
Publication: |
429/450 |
International
Class: |
H01M 8/04 20060101
H01M008/04 |
Claims
1. A fluid regulation system for a fuel cell stack comprising: a
porous element disposed in an inlet formed in a first end plate of
the fuel cell stack, a peripheral edge of the porous element
abutting a surface forming the inlet, wherein the porous element
spans the inlet, the porous element effective to collect a liquid
water from a reactant gas flowing therethrough; and a fluid
collection member disposed in an inlet conduit in fluid
communication with the inlet, the fluid collection member in fluid
communication with the porous element.
2. The system according to claim 1, wherein the porous element is
formed from a hydrophilic material.
3. The system according to claim 1, further comprising a fluid
conduit in fluid communication with the fluid collection member to
provide a flow path to drain the liquid water from the fluid
collection member.
4. The system according to claim 3, including a flow restrictor
disposed in the fluid conduit to control a flow of the reactant gas
therethrough.
5. The system according to claim 4, wherein the flow restrictor is
one of a nozzle, a wicking material, and a hydrophilic porous
element.
6. The system according to claim 3, wherein the porous element is
formed from one of a hydrophilic material and a hydrophobic
material.
7. The system according to claim 1, wherein the porous element
collects a liquid water entrained in the reactant gas flowing
through the porous element.
8. The system according to claim 7, wherein the liquid water
collected is received in the fluid collection member.
9. The system according to claim 7, wherein the liquid water
collected is evaporated into the reactant gas flowing
therethrough.
10. The system according to claim 1, wherein the porous element has
a convex first surface for collecting the liquid water.
11. A fuel cell stack assembly comprising: a first end plate; at
least one fuel cell; a fluid inlet providing a flow path for a
reactant gas to the at least one fuel cell; a porous element
disposed in the first end plate, wherein the reactant gas is caused
to flow through the porous element and into the at least one fuel
cell, the porous element effective to collect a liquid water from
the reactant gas flowing therethrough; and a fluid collection
member disposed in the fluid inlet in fluid communication with the
porous element, the fluid collection member adapted to receive the
liquid water from the porous element.
12. The fuel cell stack assembly according to claim 11, the fluid
inlet further comprising: an inlet header in communication with the
at least one fuel cell; an inlet formed in the first end plate, the
inlet in fluid communication with the inlet header; and an inlet
conduit in fluid communication with the inlet formed in the first
end plate, wherein the fluid collection member is disposed beneath
the inlet formed in the first end plate.
13. The fuel cell stack assembly according to claim 12, wherein the
porous element is a substantially cone shaped member having a
peripheral edge, the peripheral edge abutting a surface forming the
inlet, wherein the porous element spans the inlet.
14. The fuel cell stack assembly according to claim 11, wherein the
porous element is adapted to selectively collect the liquid water
entrained in the reactant gas flowing therethrough and evaporate
the liquid water into the reactant gas flowing therethrough.
15. The fuel cell stack assembly according to claim 11, further
comprising a fluid conduit in fluid communication with the fluid
collection member to provide a flow path to drain fluid from the
fluid collection member.
16. The fuel cell stack assembly according to claim 15, including a
flow restrictor disposed in the fluid conduit to control a flow of
the reactant gas therethrough.
17. The fuel cell stack assembly according to claim 15, wherein the
porous element is formed from one of a hydrophilic material and a
hydrophobic material.
18. A method of regulating liquid water flowing into a fuel cell
comprising the steps of: providing a first end plate; providing at
least one fuel cell; providing a fluid inlet in fluid communication
with the at least one fuel cell to provide a flow of a reactant gas
to the at least one fuel cell, the fluid inlet including an inlet
formed in the first end plate; providing a porous element in the
inlet formed in the first end plate, wherein the porous element
spans the inlet formed in first end plate, the porous element
effective to collect a liquid water from the reactant gas flowing
therethrough; and providing a fluid collection member in the fluid
inlet beneath the porous element, the fluid collection member
adapted to receive the liquid water from the porous element.
19. The method of claim 18, further comprising the step of draining
the liquid water from the fluid collection member.
20. The method of claim 18, wherein a peripheral edge of the porous
element contacts a surface of the inlet formed in the first end
plate.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 12/551,600 filed on Sep. 1, 2009. The entire
disclosure of the above application is incorporated herein by
reference.
FIELD OF THE INVENTION
[0002] The present disclosure relates to a fuel cell stack and more
particularly to a fuel cell stack including a system to regulate
water entrained in a reactant supply stream.
BACKGROUND OF THE INVENTION
[0003] Fuel cell power systems convert a fuel and an oxidant
(reactants) to electricity. One type of fuel cell power system
employs a proton exchange membrane (PEM) to catalytically
facilitate reaction of the fuel (such as hydrogen) and the oxidant
(such as air or oxygen) to generate electricity. Water is a
byproduct of the electrochemical reaction. The PEM is a solid
polymer electrolyte that facilitates transfer of protons from an
anode electrode to a cathode electrode in each individual fuel cell
of a stack of fuel cells normally deployed in a fuel cell power
system.
[0004] In the typical fuel cell assembly, the individual fuel cells
have fuel cell plates with channels, through which various
reactants and cooling fluids flow. Fuel cell plates may be
unipolar, for example. A bipolar plate may be formed by combining
unipolar plates. The oxidant is supplied to the cathode electrode
from a cathode inlet header and the fuel is supplied to the anode
electrode from an anode inlet header. Movement of water from the
channels to an outlet header is typically caused by the flow of the
reactants through the fuel cell assembly. Boundary layer shear
forces and a pressure of the reactant aid in transporting the water
through the channels until the water exits the fuel cell through
the outlet header.
[0005] A membrane-electrolyte-assembly (MEA) is disposed between
successive plates to facilitate the electrochemical reaction. The
MEA includes the anode electrode, the cathode electrode, and an
electrolyte membrane disposed therebetween. Porous diffusion media
(DM) are positioned on both sides of the MEA to facilitate a
delivery of reactants for the electrochemical fuel cell
reaction.
[0006] Water accumulation within the channels of the fuel cell can
result in a degradation of a performance of the fuel cell.
Particularly, water accumulation causes reactant flow
maldistribution in individual fuel cell plates and within the fuel
cell assembly, which can lead to voltage instability and a
degradation of the electrodes. Additionally, water remaining in the
fuel cell after operation may solidify in sub-freezing
temperatures, creating difficulties during a restart of the fuel
cell. Water accumulating in the channel regions includes the water
byproduct of the electrochemical reaction and water entrained in
the reactant flow streams from the cathode inlet header and the
anode inlet header.
[0007] Numerous techniques have been employed to manage water
accumulation within the fuel cell. These techniques include
pressurized purging, gravity flow, and evaporation, for example.
Additionally, the use of water transport structures and surface
coatings have been employed that facilitate the transport of water
from the channel regions of the fuel cell into an exhaust region of
the fuel cell assembly, for example. The methods to manage water
accumulation typically focus on removal of water that has
accumulated within the channels of the fuel cell and require
additional operational steps and/or components for the fuel cell.
The additional operational steps and components are known to reduce
an efficiency of operating the fuel cell and increase a cost of
manufacturing the fuel cell. Water entrained in the reactant flow
streams increases a need to employ the various techniques,
transport structures, and surface coatings to facilitate removal of
water from the tunnel regions of the fuel cell.
[0008] It would be desirable to produce a cost effective fuel cell
stack that minimizes an accumulation of water within a fuel cell
and the number of required components to facilitate a removal of
water from the fuel cell.
SUMMARY OF THE INVENTION
[0009] Compatible and attuned with the present invention, a cost
effective fuel cell stack that minimizes an accumulation of water
within a fuel cell and the number of required components to
facilitate a removal of water from the fuel cell, has been
surprisingly discovered.
[0010] In one embodiment, a fluid regulation system for a fuel cell
stack comprises a porous element disposed in a fluid inlet of the
fuel cell stack effective to collect a liquid water from a reactant
gas flowing therethrough; and a fluid collection member disposed in
the fluid inlet, the fluid collection member in fluid communication
with the porous element.
[0011] In another embodiment, a fuel cell stack assembly comprises
a first end plate and a spaced apart second end plate; at least one
fuel cell disposed between the first end plate and the second end
plate; a fluid inlet providing a flow path for a reactant gas to
the at least one fuel cell; a porous element disposed in the fluid
inlet, wherein the reactant gas is caused to flow through the
porous element and into the at least one fuel cell, the porous
element effective to collect a liquid water from the reactant gas
flowing therethrough; and a fluid collection member disposed in the
fluid inlet and adapted to receive the liquid water from the porous
element.
[0012] In another embodiment, a method of regulating liquid water
flowing into a fuel cell comprises the steps of providing a first
end plate and a spaced apart second end plate; providing at least
one fuel cell between the first end plate and the second end plate;
providing a fluid inlet in fluid communication with the at least
one fuel cell to provide a flow of a reactant gas to the at least
one fuel cell; providing a porous element in the fluid inlet
effective to collect a liquid water from the reactant gas flowing
therethrough; and providing a fluid collection member in the fluid
inlet adapted to receive the liquid water from the porous
element.
DRAWINGS
[0013] The above, as well as other advantages of the present
invention will become readily apparent to those skilled in the art
from the following detailed description, particularly when
considered in the light of the drawings described hereafter.
[0014] FIG. 1 is a schematic cross-sectional elevational view of a
fuel cell stack according to an embodiment of the invention;
[0015] FIG. 2 is top plan view of the fuel cell stack illustrated
in FIG. 1 with an end plate removed;
[0016] FIG. 3 is an enlarged fragmentary cross-sectional view of
area A shown in FIG. 1 illustrating another embodiment of the
invention;
[0017] FIG. 4 is an enlarged fragmentary cross-sectional view of
area A shown in FIG. 1 illustrating another embodiment of the
invention;
[0018] FIG. 5 is an enlarged fragmentary cross-sectional view of
area A shown in FIG. 1 illustrating another embodiment of the
invention; and
[0019] FIG. 6 is a schematic cross-sectional elevational view of a
fuel cell stack illustrating another embodiment of the
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0020] The following description is merely exemplary in nature and
is not intended to limit the present disclosure, application, or
uses. It should also be understood that throughout the drawings,
corresponding reference numerals indicate like or corresponding
parts and features.
[0021] FIG. 1 shows a fuel cell assembly 10 according to an
embodiment of the present disclosure. The fuel cell assembly 10
includes a plurality of stacked fuel cells 12 disposed between end
plates 14, 16. Each of the fuel cells 12 includes a pair of fuel
cell plates (not shown) including an inlet port 18 and an outlet
port 20 formed therein. The fuel cells 12 are stacked with the
inlet port 18 and the outlet port 20 of each fuel cell 12
substantially aligned with the respective inlet port 18 and the
outlet port 20 of an adjacent fuel cell 12. Collectively, the inlet
ports 18 of each of the fuel cells 12 form an inlet header 22 and
the outlet ports 20 of each of the fuel cells 12 form an outlet
header 24. The inlet header 22 is adapted to provide a flow of a
reactant such as a fuel (such as hydrogen) from a source of fuel or
an oxidant (such as air or oxygen) from a source of oxidant, for
example, to the fuel cells 12. The fuel cell assembly 10 shown is
illustrative of both an anode inlet header and an anode outlet
header (for the fuel), and a cathode inlet header and a cathode
outlet header (for the oxidant).
[0022] The end plate 14 includes an inlet 26 formed therein in
fluid communication with the inlet header 22 and an outlet 28
formed therein in fluid communication with the outlet header 24. An
inlet conduit (not shown) provides fluid communication from the
source of the reactant to the inlet 26 of the end plate 14. The
inlet conduit, the inlet 26 of the end plate 14, and the inlet
header 22 form a fluid inlet from the source of the reactant to the
fuel cells 12. It should be understood that the fuel cell assembly
10 typically includes a coolant inlet header in fluid communication
with a coolant inlet formed in an end plate, and a coolant outlet
header in fluid communication with a coolant outlet formed in an
end plate.
[0023] A fluid collection member 30 is provided in the inlet 26 of
the end plate 14. In the illustrated embodiment, the fluid
collection member 30 is a gutter extending outwardly from a surface
of the inlet 26 of the end plate 14. A porous element 34 having a
first end 36, a spaced apart second end 38, and opposing side edges
40, 42 shown in FIG. 2, is disposed within the inlet header 22. The
first end 36 abuts a surface of the end plate 16 and the second end
38 abuts a surface of the end plate 14 adjacent the fluid
collection member 30. The side edges 40, 42 abut opposing sides of
the inlet header 22. The porous element 34 can be a foam, a mesh, a
net, or any other material having suitable hydrophilic properties.
Further, the porous element 34 can include a support structure such
as a lattice, for example, to provide a desired rigidity or shape
to the porous element 34. The porous element 34 is adapted to
permit the flow of the reactant through the porous element 34 and
into the fuel cells 12 while causing a liquid water 39 entrained in
the reactant to collect therein and/or thereon. Favorable results
have been obtained employing a hydrophilic material for the porous
element 34. The side edges 40, 42 of the porous element 34 can be
received between the fuel cells 12 to militate against fluids
bypassing the porous element 34 by flowing around the side edges
40, 42 into the fuel cells 12. It should be understood that a seal
member can be employed to form a substantially fluid tight seal
between the side edges 40, 42 of the porous element 34 and the
surface of the inlet header 22 and/or the fuel cells 12.
Additionally, it should be understood that the seal member can be
employed to form a substantially fluid tight seal between the first
end 36 and the second end 38 of the porous element 34 and the end
plate 16 and the end plate 14, respectively.
[0024] FIG. 2 shows the fuel cell assembly 10 with the end plate 16
removed to show a surface of a fuel cell plate 44 for one of the
fuel cells 12. Each fuel cell plate 44 in the fuel cell assembly 10
includes a flow field 46 formed thereon including a plurality of
flow channels that provide fluid communication from the inlet
header 22 across the surface of the fuel cell plate 44 to the
outlet header 24. The porous element 34 is disposed in the inlet
header 22 adjacent an inlet to the flow field 46. It should be
understood that the porous element 34 and the fluid collection
member 30 can be employed in either a cathode inlet header or an
anode inlet header.
[0025] In use, the reactant is caused to flow from the source
through the inlet conduit and the inlet 26 of the end plate 14 into
the inlet header 22. The reactant flowing through the inlet header
22 is caused to pass through the porous element 34 prior to being
received in the flow field 46 of the fuel cell plates 44 of the
fuel cells 12. As the reactant passes through the porous element
34, the water 39 entrained therein is collected by the porous
element 34 and/or collected thereon, which minimizes water entering
the fuel cells 12 from the inlet header 22. The porous element 34
is formed from a material having a selected water collecting
characteristic to militate against liquid water from entering the
fuel cells 12. Further, the porous element 34 can be formed from a
material having a selected resistance to a flow of fluid
therethrough to provide a desired fluid pressure change across the
porous element 34 to facilitate forming a desired flow distribution
of the reactant into the fuel cells 12.
[0026] The fluid collection member 30 provides for a collection of
the water 39 entrained in the reactant. The water 39 collected by
the porous element 34 can drain into the fluid collection member 30
by gravitational force. A capacity of the fluid collection member
30 can be selected to accommodate a desired amount of water and
militate against the collected water, whether in liquid or solid
form, from interfering with a flow of the reactant to the fuel
cells 12 adjacent the fluid collection member 30. During periods of
operation of the fuel cell assembly 10 when the relative humidity
of the reactant is below the selected maximum relative humidity,
liquid water is evaporated from the porous element 34 into the
reactant. Liquid water in the fluid collection member 30 can be
reabsorbed by the porous element 34 and evaporated into the
reactant flowing therethrough.
[0027] The porous element 34 and the fluid collection member 30
cooperate to minimize and/or regulate the quantity of the water 39
entering the fuel cells 12 from the inlet header 22. The porous
element 34 also facilitates a uniform distribution of the water 39
entering the fuel cells 12 from the inlet header 22. Regulating the
water 39 entering the fuel cells 12 minimizes an accumulation of
liquid water in the flow field 46 of the fuel cell plates 44 which
can disrupt the flow of the reactant therethrough. By minimizing
disruptions in the flow of the reactant through the flow field 46
of the fuel cell plates 44, electrode degradation and other failure
mechanisms of the fuel cell assembly 10 are minimized, and
electrical voltage stability and efficient operation of the fuel
cell assembly 10 are maximized. Additionally, by minimizing an
accumulation of liquid water in the flow field 46 of the fuel cell
plates 44, the likelihood that frozen water will form therein
during periods of low temperature operation of the fuel cell 10
such as a start-up period, for example, is also minimized. Frozen
water in the flow field 46 of the fuel cell plates 44 can disrupt
the flow of the reactant and cause a degradation of the components
of the MEA by placing an increased compressive force thereon as a
result of the volumetric expansion associated with the freezing of
water. Accordingly, minimizing the accumulation of liquid water in
the flow field 46 of the fuel cell plates 44 can minimize a
likelihood of frozen water form disrupting the flow of the
reactants therethrough or causing a degradation of the components
of the MEA. Further, by minimizing and/or regulating the quantity
of the water 39 entering the fuel cells 12, processes and
components for the fuel cell assembly 10 adapted to manage and/or
remove water from the fuel cells 12 can be eliminated or minimized.
The elimination or minimization of such processes and components
can minimize a cost of manufacturing the fuel cell assembly 10
and/or the number of components required for the fuel cell assembly
10, and can maximize an operational efficiency of the fuel cell
assembly 10.
[0028] FIG. 3 illustrates an alternate embodiment of the invention.
Structure similar to that illustrated in FIG. 1 includes the same
reference numeral and a prime (') symbol for clarity. In the
embodiment shown, a fluid conduit 50 is formed adjacent and in
fluid communication with the fluid collection member 30'. The fluid
conduit 50 provides fluid communication between the fluid
collection member 30' and a water exhaust conduit (not shown). In
the illustrated embodiment, the fluid conduit 50 is formed in the
end plate 14'. It should be understood that the fluid conduit 50
can be an elongate tube providing fluid communication between the
fluid collection member 30' and the water exhaust conduit. A flow
restrictor 52 such as a nozzle, for example, is provided within the
fluid conduit 50 to regulate the flow of fluid through the fluid
conduit 50.
[0029] In use, the fluid conduit 50 provides a flow path for liquid
water collected in the fluid collection member 30' to exhaust
therefrom. A fluid pressure of the reactant flowing through the
inlet header 22' provides a driving force for the liquid water in
the fluid collection member 30' to flow through the fluid conduit
50 to the water exhaust conduit. A quantity of reactant gas may
also flow through the fluid conduit 50 which would reduce the
quantity of reactant gas supplied to the fuel cells 12'. The flow
restrictor 52 minimizes the flow of reactant through the fluid
conduit 50 to minimize the quantity of the reactant gas that can
bypass the fuel cells 12' and flow into the water exhaust conduit.
The flow restrictor 52 can be adapted to restrict the flow of the
reactant gas through the fluid conduit 50 to less than about 1% of
the total flow of the reactant gas in the inlet header 22', while
still causing liquid water to flow to the water exhaust line. It
should be understood that an actuated valve can be employed with
the fluid conduit 50 to selectively control the flow of fluid
therethrough. The fluid conduit 50 and flow restrictor 52 are
particularly effective for managing water in a cathode inlet header
where a small quantity of cathode reactant, typically atmospheric
air or oxygen, bypassing the fuel cells 12' is generally
acceptable.
[0030] FIG. 4 illustrates an alternate embodiment of the invention.
Structure similar to that illustrated in FIG. 1 includes the same
reference numeral and a prime (') symbol for clarity. As shown, a
fluid conduit 60 is formed adjacent and in fluid communication with
the fluid collection member 30'. The fluid conduit 60 provides
fluid communication between the fluid collection member 30' and a
water exhaust conduit (not shown). A wicking element 62 is disposed
in the fluid conduit 60 which militates against the reactant gas
from flowing through the fluid conduit 60 to the water exhaust
conduit. In the illustrated embodiment, the fluid conduit 60 is
formed in the end plate 14'. It should be understood that the fluid
conduit 60 can be an elongate tube providing fluid communication
between the fluid collection member 30' and the water exhaust
conduit. Additionally, it should be understood that the fluid
conduit 60 is not required and the wicking element 62 can be in
fluid communication with the interior of the fluid collection
member 30' and the water exhaust conduit directly.
[0031] In use, the fluid conduit 60 provides a flow path for liquid
water collected in the fluid collection member 30' to exhaust
therefrom. Liquid water in the fluid collection member 30' flows
through the wicking element 62 disposed in the fluid conduit 60 by
capillary forces. The liquid water flows through the wicking
element 62 and then continues to flow through the fluid conduit 60
to the water exhaust conduit. Employing the wicking element 62
militates against reactant gas flowing through the fluid conduit 60
and bypassing the fuel cells 12'. The wicking element 62 is
particularly suited for managing water in an anode inlet header
where it is typically desired to have no reactant, typically
hydrogen gas, bypass the fuel cells 12'.
[0032] In certain applications, the wicking element 62 may permit
an amount of the reactant gas which exceeds a desired amount to
flow into the water exhaust conduit and bypass the fuel cells 12'
such as when the fluid pressure of the reactant gas exceeds a
critical fluid pressure in respect of the wicking element 62, for
example. It is anticipated that a critical fluid pressure for a
typical wicking element 62 would be between about 10 kPa and 20
kPa. As shown in FIG. 5, in a fuel cell assembly 10' employing a
reactant gas having a fluid pressure that exceeds the critical
fluid pressure of the wicking element 62, the wicking element 62
can be replaced with a series of two or more spaced apart
hydrophilic porous elements 64 disposed in the fluid conduit 60.
Each hydrophilic porous element 64 provides a selected differential
pressure thereacross. The series of the hydrophilic porous elements
64 is adapted to militate against the reactant gas passing
therethrough while allowing liquid water to pass therethrough.
Typically, the hydrophilic porous elements 64 are kept sufficiently
wet with liquid water to maintain the desired differential pressure
thereacross. Accordingly, at least a portion of the fluid conduit
60 including the hydrophilic porous elements 64 can be oriented in
a horizontal position to facilitate retaining liquid water therein
to keep the hydrophilic porous elements 64 sufficiently wetted.
Further, liquid water can be provided to the hydrophilic porous
elements 64 from water entrained in exhaust flowing from the outlet
header and/or another suitable source of liquid water, for example.
It should be understood that the flow restrictor 52, the wicking
element 62, and the hydrophilic porous element 64 can be employed
separately or in any combination thereof in the fluid conduit 60 to
militate against the reactant gas from bypassing the fuel cells
12'.
[0033] FIG. 6 illustrates an alternate embodiment of the invention.
Structure similar to that illustrated in FIG. 1 includes the same
reference numeral and a prime (') symbol for clarity. In the
embodiment shown, the porous element 34' is disposed in the inlet
26' of the end plate 14'. The porous element 34' is a substantially
cone shaped member having a peripheral edge 70 and a first surface
72. The peripheral edge 70 of the porous element 34' abuts a
surface of the inlet 26'. It should be understood that other shapes
can be employed for the porous element 34' such as a substantially
planar member or other suitable curvilinear shapes, for example. An
inlet conduit 74 is provided in fluid communication with the inlet
26' of the end plate 14'. The inlet conduit 74 includes a fluid
collection member 76 having a fluid conduit 78 in fluid
communication with the collection member 76 and a water exhaust
conduit (not shown). A flow restrictor 80 such as a nozzle, for
example, is provided within the fluid conduit 78 to militate
against flow of the reactant gas therethrough.
[0034] In use, the inlet conduit 74 provides a flow path for the
reactant gas to the inlet 26' of the end plate 14'. The reactant is
caused to pass through the porous element 34' prior to being
received by the inlet header 22'. The water 39' absorbed by or
collected on the first surface 72 of the porous element 34' can
flow by gravitational force into the fluid collection member 76. A
fluid pressure of the reactant flowing through the inlet conduit 74
provides a driving force for the liquid water in the fluid
collection member 76 to flow through the fluid conduit 78 to the
water exhaust conduit. A quantity of reactant gas may also flow
through the fluid conduit 78 which would reduce the quantity of
reactant gas supplied to the fuel cells 12'. The flow restrictor 80
minimizes the flow of reactant through the fluid conduit 78 to
minimize the quantity of the reactant gas that can bypass the fuel
cells 12' and flow into the water exhaust conduit. The flow
restrictor 80 can be adapted to restrict the flow of the reactant
gas through the fluid conduit 78 to less than about 1% of the total
flow of the reactant gas in the inlet header 22', while still
causing liquid water to flow to the water exhaust line. It should
be understood that an actuated valve can be employed with the fluid
conduit 78 to selectively control the flow of fluid therethrough.
It should be understood that the wicking element 62 and the
hydrophilic porous elements 64 (illustrated in FIGS. 4 and 5,
respectively), can be employed separately or in combination with
each other and the flow restrictor 80 in the fluid conduit 78 to
militate against the reactant gas bypassing the fuel cells 12'.
[0035] The porous element 34' in the embodiments illustrated in
FIGS. 3-6 can be a hydrophilic or a hydrophobic material. When
employing the hydrophobic material, the water 39 entrained in the
reactant is collected on a surface of the hydrophobic material,
forming water droplets thereon, which fall into the respective
fluid collection members by gravitational force. The collected
liquid water is exhausted to the water exhaust conduit. The use of
a hydrophobic material is particularly effective when it is not
desired to evaporate a substantial quantity of collected liquid
water into the reactant entering the fuel cells 12' from the inlet
header 22'. The remaining structure and function of the embodiments
illustrated in FIGS. 3-6 is substantially equivalent to the
structure and function of the embodiment illustrated in FIGS.
1-2.
[0036] While certain representative embodiments and details have
been shown for purposes of illustrating the invention, it will be
apparent to those skilled in the art that various changes may be
made without departing from the scope of the disclosure, which is
further described in the following appended claims.
* * * * *