Claims:We claim:

1. A bipolar plate assembly (100) for a fuel cell (101), the assembly (100) comprising:
a first plate (3) configured as a hydrogen side of the bipolar plate assembly (100), the first plate (3) comprising:
a hydrogen inlet manifold (10);
a hydrogen outlet manifold (11) on a side opposite to the hydrogen inlet manifold (10); and
a hydrogen distribution channel (20) defined on a major surface of the first plate (3) between the hydrogen inlet manifold (10) and the hydrogen outlet manifold (11);
a second plate (4) configured as an air side of the bipolar plate assembly (100), the second plate (4) comprising:
an air inlet manifold (14);
an air outlet manifold (15) on a side opposite to the air inlet manifold (14); and
an air distribution channel (21) defined on a major surface of the second plate (4) between the air inlet manifold (14) and the air outlet manifold (15),
wherein, at least one of the hydrogen distribution channel (20) and the air distribution channel (21) are defined with a plurality of lanceolate protrusions in a plurality of arrays.

2. The assembly (100) as claimed in claim 1, wherein both the hydrogen distribution channel (20) and the air distribution channel (21) are defined with a plurality of lanceolate protrusions (E) in the plurality of arrays.

3. The assembly (100) as claimed in claim 1, wherein each of the plurality of lanceolate protrusions (E) in the hydrogen distribution channel (20) and the air distribution channel (21) is defined with at least one serrated dent (E1).

4. The assembly (100) as claimed in claim 1, wherein the second plate (4) is defined with a plurality of tapered protrusions (16) in at least one of the downstream of the air inlet manifold (14) and the upstream of the air outlet manifold (15) to facilitate air flow distribution.

5. The assembly (100) as claimed in claim 1, wherein the first plate (3) is defined with the plurality of tapered protrusions (16) and a plurality of circular protrusions (17) in at least one of a downstream of the hydrogen inlet manifold (10) and upstream of the hydrogen outlet manifold (11) to facilitate flow distribution.

6. The assembly (100) as claimed in claim 5, wherein the plurality of circular protrusions (17) are defined downstream of the plurality of the tapered protrusions (16) on the first plate (3).

7. The assembly (100) as claimed in claim 1, wherein each of the plurality of lanceolate protrusions (E) are at least one of lanceolate shaped depressions and cut-outs.

8. The assembly (100) as claimed in claim 1, wherein the plurality of serrated dents (E1) are defined on the at least one of lanceolate shaped depressions and cut-outs.

9. The assembly (100) as claimed in claim 1, wherein a coolant flow channel (22) is defined on a rear side of at least one of the first plate (3) and the second plate (4), the coolant flow channel (22) co-operates with a coolant inlet manifold (12) and a coolant outlet manifold (13) defined in at least one of the first plate (3) and the second plate (4).

10. The assembly (100) as claimed in claim 1, wherein the first plate (3) and the second plate (4) are configured such that the hydrogen distribution channel (20) defined on the major surface of the first plate (3) is oriented opposite to the air distribution channel (21) defined on the major surface of the second plate (4).

11. A polymer electrolyte membrane fuel cell comprising a bipolar plate assembly (100) as claimed in claim 1.

Dated 31st day of December 2019

Gopinath Arenur Shankararaj
IN/PA 1852
OF K&S PARTNERS
AGENT FOR THE APPLICANT
, Description:FORM 2
THE PATENTS ACT 1970
[39 OF 1970]
&
The Patents Rules, 2003

COMPLETE SPECIFICATION
[See section 10 and rule 13]

TITLE: “A BIPOLAR PLATE ASSEMBLY FOR A FUEL CELL”

Name and address of the Applicant:
TATA MOTORS LIMITED, an Indian company having its registered office at Bombay House, 24 Homi Mody Street, Mumbai 400 001, Maharashtra, INDIA.

Nationality: INDIAN

The following specification particularly describes the invention and the manner in which it is to be performed.
TECHNICAL FIELD

Present disclosure generally relates to a field of automobiles. Particularly but not exclusively present disclosure relates to a fuel cell. Further, embodiments of the present disclosure disclose a bipolar plate assembly for a fuel cell that may be employed in a vehicle.

BACKGROUND OF THE INVENTION

Fuel cell is an electrochemical cell which converts chemical energy of a fuel into an electrical energy. Unlike a conventional battery, the fuel cell may continuously produce electricity as long as fuel in the form of hydrogen and air are supplied thereto. The fuel cell system may generally comprise a fuel cell stack for generating electricity, a fuel supply system for supplying fuel like hydrogen to the fuel cell stack, an air supply system for supplying oxygen. The oxygen may act as an oxidizing agent required for an electrochemical reaction, in the fuel cell stack.

With the depletion of non-renewable energy, fuel cells are expected to play a major role as a sustainable technology for power generation in wide variety of applications. One such application may be automotive applications. The fuel cell which may be considered as future automotive propulsion applications is a Polymer Electrolyte Membrane Fuel Cell (PEMFC). The PEMFC system is an energy system that converts hydrogen and oxygen (or air) to electricity with water as by-product, and hence is of great interest from an environmental point of view. A significant part of the PEMFC stack is bipolar plates, which may account for about 60% of total weight and 40% of stack cost. The bipolar plates may be designed to accomplish many functions, such as distribution of reactants uniformly over the active areas, remove heat from the active areas, carry current from cell to cell and prevent leakage of reactants and coolant. Therefore, it may be advantageous if the bipolar plates are inexpensive, lightweight materials, easily and inexpensively manufactured. Many efforts have been made to develop bipolar materials that satisfy these demands. The main materials used for bipolar plates may include electro graphite, sheet metal (coated and uncoated) and graphite polymer composites.

Delivery of reactants, removal of products and efficient heat removal from the PEMFC stack is crucial for optimum performance and durability. Power capacity value of a PEMFC may be greatly influenced by the flow field design. Homogeneous current density and temperature distribution along with effective water removal are crucial tasks, and thus require a careful flow field design in a PEMFC.
Maintaining the polymer electrolyte membrane in a humid state is important for obtaining a stable current density. The polymer electrolyte membrane allows only the positively charged ions to pass through and prevents the negatively charged electrons from by-passing, thereby causing the electrons to flow in an external circuit, creating an electric current. This, electric current density varies when the humidity of the proton electrolyte membrane is severely low or severely high. Thus, in fuel cell stack, humidity plays vital role to ensure the stable performance. Stable performance is achieved when the membrane is kept hydrated to get increased current density. Conventionally, most of fuel cell manufactures employ external humidification system to humidify the incoming unsaturated dry air from supercharger. The humidified air from the external humidification system is further circulated to the bi-polar plates of the fuel cell. However, the external humidification chambers are bulky, which may result in an increase of the overall weight of the system. The external humidification system also comprises of several components which further increases the overall complexity of the system.

With advancements in technologies, the fuel cell manufacturers employed self-humidified fuel cell system, which may facilitate inside humidification of the fuel cell without adding the external system or components. Most of the fuel cells comprise of two bi-polar plates, where one of the plate is an anode, whereas the other plate is the cathode. Each of the anode and cathode plates comprise of flow channels along which hydrogen is usually circulated through the anode plate, whereas air is circulated along the cathode plate. Conventionally bi-polar plates are defined with serpentine or straight flow channels and the water used for humidifying the fuel cell often floods in the flow channels. The flooding of water further leads to the over humidification of the fuel cell. Consequently, resulting in variation and non-uniform distribution of current density. Also, since these flow channels are generally lengthy straight paths for the flow of hydrogen or air, the efficiency with respect to the air or the hydrogen being humidified by the stagnant water may be very low. The hydrogen and air will mix with very small amounts of water vapor since the hydrogen and air would flow past the water. Thus, hydrogen and air may not be thoroughly humidified.

Some of the conventional bipolar plates and the flow-field designs of such plate are discussed below.

A pin type bipolar plate design is available, in which the fluids flow through the grooves formed by the pins protruding from the plates. Another Bipolar plate uses parallel channel for fluid flow. A crisscross form of flow is induced in one bipolar plate in order for the gas to coalesce with water droplets. A bipolar plate with single serpentine flow path is also available, in which the fluid flow through a continuous path from start to end. Bipolar plates with parallel serpentine flow path, serpentine flow path divided into linked segments, serpentine flow path that are mirror images etc. are also available. Another bipolar plate design uses dead-ended discontinuous channels to force the gases through a gas diffusion layer under the landings to pass from the manifold inlet to outlet streams. A modified interdigitated bipolar plate in which larger channels are branched into smaller ones are also available. In another type of bipolar plate, usual rectangular flow channels are replaced with radial flow rings.

The aforementioned conventional bipolar plates have some associated disadvantages such as uneven current density, water blockage in channels resulting in obstructed flow, uneven reactant distribution and corrosion issues.

The present disclosure is directed to overcome one or more limitations stated above, or any other limitation associated with the prior arts.

SUMMARY OF THE DISCLOSURE

One or more shortcomings of the conventional system or device are overcome, and additional advantages are provided through the provision of the device as claimed in the present disclosure.

Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.

In one non-limiting embodiment of the disclosure, a bipolar plate assembly for a fuel cell is disclosed. The assembly comprises of a first plate configured as a hydrogen side of the bipolar plate assembly. The first plate comprises of a hydrogen inlet manifold, a hydrogen outlet manifold on a side opposite to the hydrogen inlet manifold is provided and a hydrogen distribution channel defined on a major surface of the first plate between the hydrogen inlet manifold and the hydrogen outlet manifold. Further, a second plate is configured as an air side of the bipolar plate assembly. The second plate comprises of an air inlet manifold and an air outlet manifold on a side opposite to the air inlet manifold. An air distribution channel is defined on a major surface of the second plate between the air inlet manifold and the air outlet manifold. Further, at least one of the hydrogen distribution channel and the air distribution channel are defined with a plurality of lanceolate protrusions are in a plurality of arrays.

In an embodiment of the disclosure, both of the hydrogen distribution channel and the air distribution channel are defined with a plurality of lanceolate protrusions arranged in a plurality of arrays.

In an embodiment of the disclosure, each of the plurality of lanceolate protrusion in the hydrogen distribution channel and the air distribution channel are defined with at least one serrated dent.

In an embodiment of the disclosure, the second plate is defined with a plurality of tapered protrusions in at least one of the downstream of the air inlet manifold and the upstream of the air outlet manifold to facilitate air flow distribution.

In an embodiment of the disclosure, the first plate is defined with the plurality of tapered protrusions and a plurality of circular protrusions in at least one of a downstream of the hydrogen inlet manifold and upstream of the hydrogen outlet manifold to facilitate flow distribution.

In an embodiment of the disclosure, the plurality of circular protrusions is defined downstream of the plurality of the tapered protrusions on the first plate.

In an embodiment of the disclosure, each of the plurality of lanceolate protrusions are at least one of lanceolate shaped depressions and cut-outs.

In an embodiment of the disclosure, wherein the plurality of serrated dents is defined on the at least one of lanceolate shaped depressions and cut-outs.

In an embodiment of the disclosure, a coolant flow channel is defined in a rear side of at least one of the first plate and the second plate and the coolant flow channel co-operates with a coolant inlet manifold and a coolant outlet manifold defined in at least one of the first plate and the second plate.

In an embodiment of the disclosure, the first plate and the second plate are configured such that the hydrogen distribution channel defined on the major surface of the first plate is oriented opposite to the air distribution channel defined on the major surface of the second plate.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES

The novel features and characteristic of the disclosure are set forth in the appended claims. The disclosure itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying figures. One or more embodiments are now described, by way of example only, with reference to the accompanying figures wherein like reference numerals represent like elements and in which:

Fig. 1 illustrates an exploded perspective of a fuel cell stack, according to an embodiment of the present disclosure.

Fig. 2 illustrates an exploded perspective view of a bipolar plate assembly of the fuel cell, according to an embodiment of the present disclosure.

Fig. 3 illustrates a front view of a first plate of the bipolar plate assembly of Fig. 2, according to an embodiment of the present disclosure.

Fig. 3a illustrates a magnified view of a portion [C] of the hydrogen distribution channel in the first plate, according to an embodiment of the present disclosure.

Fig. 4 illustrates a front view of a second plate of the bipolar plate assembly of Fig. 2, according to an embodiment of the present disclosure.

Fig. 4a illustrates a magnified view of a portion [D] of the air distribution channel in the second plate, according to an embodiment of the present disclosure.

Figs. 5 and 6 illustrates magnified views of the flow channels of the first and second plates, wherein the pattern of flow channels are lanceolate shaped, in accordance with an embodiment of the present disclosure.

The figure depicts embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the system for operating the bi-polar plates of the fuel cell illustrated herein may be employed without departing from the principles of the disclosure described herein.

DETAILED DESCRIPTION

The foregoing has broadly outlined the features and technical advantages of the present disclosure in order that the description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter which form the subject of the disclosure. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other devices for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the disclosure. The novel features which are believed to be characteristic of the disclosure, as to its organization, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure.

In the present document, the word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment or implementation of the present subject matter described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

While the disclosure is susceptible to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the drawings and will be described below. It should be understood, however that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the scope of the disclosure.

The terms “comprises”, “comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a system that comprises a list of components does not include only those components but may include other components not expressly listed or inherent to such mechanism. In other words, one or more elements in the device or mechanism proceeded by “comprises… a” does not, without more constraints, preclude the existence of other elements or additional elements in the mechanism.

Embodiments of the present disclosure discloses a bipolar plate assembly for a fuel cell. Conventionally, in the fuel cells external humidification system are employed to humidify the incoming unsaturated dry air from supercharger. The humidified air from the external humidification system is further circulated to the bi-polar plates of the fuel cell. However, the external humidification chambers are bulky, which result in an increase of the overall weight of the system. Also, the conventional bi-polar plates defined with serpentine or straight flow channels and the water used for humidifying the fuel cell often caused the flooding in the flow channels.

Accordingly, the present disclosure discloses a bipolar plate assembly for a fuel cell. The bi-polar plate assembly according to various embodiments of the disclosure includes a first plate configured as a hydrogen side of the bipolar plate assembly. The first plate comprises of a hydrogen inlet manifold and a hydrogen outlet manifold on a side opposite to the hydrogen inlet manifold. There is a hydrogen distribution channel defined on a major surface of the first plate between the hydrogen inlet manifold and the hydrogen outlet manifold. Further, a second plate is configured as an air side of the bipolar plate assembly. The second plate comprises of an air inlet manifold and an air outlet manifold on a side opposite to the air inlet manifold. An air distribution channel is defined on a major surface of the second plate between the air inlet manifold and the air outlet manifold. Further, at least one of the hydrogen distribution channel and the air distribution channel are defined with a plurality of lanceolate protrusions in a plurality of arrays. Further, each of the lanceolate protrusions comprise of at least one serrated dents. The lanceolate protrusions and the serrated dents create turbulence in the flow of hydrogen and oxygen. The turbulence causes the hydrogen and the air to be thoroughly humidified by the water vapor present in the bi-polar plates.

The following paragraphs describe the present disclosure with reference to Figs. 1 to 6.

Fig. 1 illustrates a perspective view of a fuel cell stack (101). The fuel cell includes a first plate (3) and a second plate (4). The first and the second plate (3 and 4) are accommodated in close proximity of at least one current collector. Each of the first and the second plates (3 and 4) are further connected to a gas diffusion layer (6) by means of a dispensed gasket (5). The connection between each of the first, second plate (3,4) and the gas diffusion layers (6) is sealed by the dispensed gasket (5). Further, between each of the gas diffusion layers (6), a first catalyst (7) and a second catalyst (8) are accommodated and a membrane (9) is housed between the first and the second catalysts (7 and 8). The first catalyst (7) is housed towards the first plate (3) and the second catalyst (8) is housed towards the second plate (4). As seen from the Fig. 1, the first and second plates (3 and 4) is provided with a coolant flow channel (22) and is sealed by the first sealing gasket (18). Similarly, another coolant flow channel (22) [not shown] is also provided adjacent to the second plate (4) and is also sealed by a first sealing gasket (18). In an embodiment, the fuel cell stack (101) is encased by two end plates [not shown] and comprises plurality of current collectors [not shown]. The end plates suitably house and support the fuel cell stack (101) and the current collectors direct the electrons to an external circuit.

In the exemplary configuration, the first plate (3) is configured as hydrogen side plate and the second plate (4) configured as an air side, and these two plates together form the bipolar plate assembly (100) [shown in Fig. 2]. The first plate (3) through which the hydrogen is circulated acts as the anode, whereas the second plate (4) through which air is circulated acts as a cathode. As the hydrogen is circulated through the first plate (3), the hydrogen diffuses through the gas diffusion layer (6) and reaches the first catalyst (7). The first catalyst (7) separates the hydrogen into positively charged hydrogen ions and electrons. These positively charged hydrogen ions and electrons further diffuse from the first catalyst (7) and come in contact with the proton exchange membrane (9). The proton exchange membrane (9) allows only the positively charged hydrogen ions to pass through, whereas the flow of electrons may be blocked. The electrons may thus force to flow through an external circuit by means of the current collectors. The positively charged hydrogen ions travel through the proton exchange membrane (9) and reach the second catalyst (8), whereas the electrons flow from the current collector near the first plate (3) to the current collector near the second plate (4) through an external circuit, thereby generating electricity. This electricity may be used for suitable productive purposes such as driving an electric motor in a vehicle. As hydrogen is being circulated through the first plate (3), air is also simultaneously being circulated through the second plate (4). The air diffuses through the gas diffusion layer (6) that is housed proximal to the second plate (4) and reaches the second catalyst (8). The electrons which have travelled through the external circuit from the current collector near the first plate (3) to the current collector near the second plate (4), also reach the second catalyst. The electrons, the positively charged hydrogen ions and the oxygen in the air undergo an exothermic reaction in the second catalyst to form water near the second plate (4). The water that is already created near the second plate (4) may further be heated up by the exothermic reaction to form water vapor. The water or the water vapor, is further used to humidify the proton exchange membrane (9) of the fuel cell (101).

The bipolar plate assembly (100) of the present disclosure will be explained with greater detail in subsequent paragraphs.

In an embodiment of the disclosure, the first and the second catalyst (7 and 8) may be made of platinum material. Further, the catalyst used must not be limited to platinum.

Fig. 2 is an exemplary embodiment of the present disclosure illustrating exploded perspective view of the bipolar plate assembly (100) for a fuel cell (101). The bipolar plate assembly (100) may be configured with a coolant flow channel (22) on a rear side of at least one of the first plate (3) and the second plate (4). Further, a first sealing member (18) and a second sealing member (19) are provided on either sides of the coolant flow channel (22). The first sealing member (18) may be provided between the coolant flow channel (22) and the first or the second plate (3 and 4). Further, a second sealing member (19) may be provided at a rear end of the coolant flow channel (22). The first and second sealing members (18 and 19), seal the coolant flow channel (22) with the first or the second plates (3/4), such that the coolant flowing through the coolant flow channel (22) may come in direct contact with the rear end of the first or the second plate (3/4). The coolant flow channels (22) may co-operate with a coolant inlet manifold (12) and a coolant outlet manifold (13) and circulates a coolant such as water. The circulation of the coolant through the coolant flow channel (12) helps in dissipation of heat generated in the first plate (3) and the second plate (4). The circulation of coolant may also help in selectively heating the first and second plates (3 and 4) in certain conditions including but not limiting to cold ambient conditions. In an embodiment of the disclosure, the first sealing member (18) and the second sealing member (19) may be made of any suitable material including but not limiting to polymeric material. The polymeric material may be Polytetrafluoroethylene and the like. The first sealing member (18) and the second sealing member (19) may be defined with pockets on an internal surface. The pockets are configured to seal each fluid transfer area in the first plate (3) and the second plate (4). This ensure leak proof joints in the bipolar plate assembly (100).

In an embodiment, the configuration of coolant flow channel (110) in the bipolar plate assembly (100) results in efficient heat removal.

Moving on to Fig. 3, it illustrates a front view of the first plate (3) of the bipolar plate assembly (100). The first plate (3) may be configured as hydrogen-side plate also referred to as anode side. The first plate (3) may be made of a metallic or a graphite material and may be defined with a predetermined thickness. In an embodiment, the first plate (3) and the second plate (4) may be made of any material including but not limiting to metallic material and graphite. The first plate (3) includes a front side and a rear side. The major surface of the front side in the first plate (3) may be defined with a hydrogen distribution channel (20) for supplying hydrogen to the fuel cell which acts as fuel. The first plate (3) may be further defined with a hydrogen inlet manifold (10) and a hydrogen outlet manifold (11). In an embodiment, the hydrogen distribution channel (20) may be configured between the hydrogen inlet manifold (10) and the hydrogen outlet manifold (11). In an embodiment, the hydrogen inlet manifold (10) may be defined in a substantially upper portion (3a) of the first plate (3), and the hydrogen outlet manifold (11) may be defined in a substantially bottom portion (3b) of the first plate (3). The hydrogen inlet manifold (10) may be fluidly connected to a hydrogen source, such that hydrogen flows from top of the first plate (3a) to bottom of the first plate (3b).

With reference to Fig. 3a, the first plate (3) may also be provided with a plurality of tapered protrusions (16) and a plurality of circular protrusions (17) in downstream side of the hydrogen inlet manifold (10) and an upstream side of the hydrogen outlet manifold (11). The configuration of the plurality of tapered protrusions (16) and the circular protrusions (17) facilitate uniform distribution of the hydrogen supplied from the hydrogen inlet manifold (10) into the hydrogen distribution channel (20) and then to the hydrogen outlet manifold (11). In an embodiment, the plurality of tapered protrusions (16) and the circular protrusions (17) may be stamped on the first plate (3) using suitable stamping technique. The hydrogen enters through the hydrogen inlet manifold (10) and flows downstream of the first plate (3). The tapered protrusions (16) and the circular protrusions (17) facilitate uniform distribution of the hydrogen supplied from the hydrogen inlet manifold (10) into the hydrogen distribution channel (20). The hydrogen distribution channel (20) is defined with a plurality of lanceolate protrusions (E) in a plurality of arrays. Figs. 5 and 6 illustrates magnified views of the lanceolate protrusions (E) along the hydrogen flow channel (20). These lanceolate protrusions (E) are further defined with at least one serrated dents (E1). With further reference to the above mentioned working of the fuel cell, the water and the water vapor that is generated near the second plate (4) during the exothermic reaction diffuses through the gas diffusion layer (6) may get accumulated along the hydrogen flow channel (20) of the first plate (3). In an embodiment, the water vapor may be accumulated along the spaces between the plurality of lanceolate protrusions (E). As the hydrogen flows along the hydrogen distribution channel (20), the serrated dents (E1) of the lanceolate protrusions (E) creates turbulence in the flow area and forms a vortex. The flow of hydrogen is constantly interrupted by the serrated dents (E1) and hydrogen continuously undergoes changes in magnitude and direction. Consequently, turbulence in the flow of hydrogen along the hydrogen flow channel (20) is created. The turbulence and the vortex created during the flow of the hydrogen through the hydrogen flow channel (20) causes the dry hydrogen to be thoroughly humidified by the water vapor accumulated along the hydrogen flow channel (20). The turbulence causes the hydrogen and the water vapor to mix up. Thus, the dry hydrogen may be humidified. The turbulence created by the lanceolate protrusions (E) also increases the rate of diffusion in the diffusion layer (6) so that highest reaction may occur in the first catalyst (7) area, consequently improving performance in fuel cell (101) operation. The humidified hydrogen diffuses through the gas diffusion layer (6) and further humidifies the proton exchange membrane (9). This aspect of hydrating the proton exchange membrane (9) by means of the humidified hydrogen, enables the fuel cell to maintain a constant current density.

Fig. 4 illustrates a front view of the second plate (4) of the bipolar plate assembly (100). The second plate (4) may be configured as air side plate also referred to as cathode side. The second plate (4) may be made of a metallic or a graphite material and is defined with a predetermined thickness. The second plate (4) includes a front side and a rear side. The major surface of the front side in the second plate (4) may be defined with an air distribution channel (21) for supplying air. The second plate (4) may be defined with an air inlet manifold (14) and an air outlet manifold (15) and the air distribution channel (21) may be configured in between the air inlet manifold (14) and the air outlet manifold (15). In an embodiment, the air inlet manifold (14) may be defined in a substantially bottom portion (4b) of the second plate (4), and the air outlet manifold (15) may be defined in a substantially upper portion (4a) of the second plate (4). The air inlet manifold (14) may be fluidly connected to an air source, such that air flows from bottom of the second plate (4b) to top of the second plate (4a).

With further reference to Fig. 4a, the second plate (4) is also provided with a plurality of tapered protrusions (16) in downstream side of the air inlet manifold (14) and an upstream side of the air outlet manifold (15). The configuration of the plurality of tapered protrusions (16) facilitate uniform distribution of the air supplied from the air inlet manifold (14) into the air distribution channel (21) and then to the air outlet manifold (15). In an embodiment, the plurality of tapered protrusions (16) may be stamped on the second plate (4) using suitable stamping technique. The air distribution channel (21) is also defined with a plurality of lanceolate protrusions (E) in a plurality of arrays.

Further, Figs. 5 and 6 which illustrates a magnified view of the lanceolate protrusions (E) along the air flow channel (21). These lanceolate protrusions (E) are defined with at least one serrated dents (E1). Further, the water vapor generated near the second plate (4) gets accumulated along the air flow channel (21) of the second plate (4). As the air flows along the air distribution channel (21), the lanceolate protrusions (E) creates turbulence in the flow area and forms a vortex. The serrated dents (E1) of the lanceolate protrusion (E) cause the air to undergo irregular fluctuations and causes the mixing of the air and the water vapor. Since, the flow of air is constantly interrupted by the serrated dents (E1), the air continuously undergoes changes in magnitude and direction. Consequently, turbulence in the flow of air along the air flow channel (21) is created. The turbulence and the vortex created during the flow of the air through the air flow channel (21) causes the dry air to be thoroughly humidified by the water vapor that has accumulated along the air flow channel (21). The turbulence created by the lanceolate protrusions (E) also increases the rate of diffusion of air through the diffusion layer (6) proximal to the second plate (4), so that highest reaction may occur in the second catalyst (8) area. The ample supply of humidified air improves the exothermic reaction that occurs at the second catalyst (8). Consequently, the overall performance of the fuel cell (101) may also be improved. The humidified air diffuses through the gas diffusion layer (6) and further humidifies the proton exchange membrane (9).

The current density from the fuel cell remains stable only when the flow of electron in the external circuit is stable. The constant flow of electron is achieved when the proton exchange membrane (9) allows only the protons to pass through and completely blocks the passage of electrons. The above condition can only be achieved when the proton exchange membrane (9) is suitably hydrated. Since, both the hydrogen and the air flowing from the first and second plate (3 and 4), contribute towards hydrating the proton exchange membrane (9), a constant flow of electrons in the external circuit is achieved and a constant current density is maintained.

In an embodiment, the lanceolate protrusions (E) may be lanceolate patterns that are etched, engraved or provided through any other suitable means on the first and the second plates (3 and 4). The serrated dents (E1) may further be provided on each of the lanceolate patterns of the first and the second plate (3 and 4).

In an embodiment, the first plate (3) and the second plate (4) may be made of any material including but not limiting to metallic material and a graphite and bonded together along with the first sealing member (18).

In an embodiment, the configuration of the bipolar plate assembly (100) facilitates self-humification of air and hydrogen, thereby saves energy required for humidifying the air.

In an embodiment, the bipolar plate assembly (100) is less prone for fouling, since high turbulence created by the lanceolate protrusions (E) induce the through humidification of hydrogen and air and thereby hydrate the proton exchange membrane (9). This configuration improves and stabilizes the current density.

In an embodiment flow channels design comprising the lanceolate protrusions (E) ensures that no flooding of water in the flow channel area (20 and 21) occurs.

Equivalents

With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.

It will be understood by those within the art that, in general, terms used herein, are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding the description may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should typically be interpreted to mean "at least one" or "one or more"); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to "at least one of A, B, and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to "at least one of A, B, or C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B."

While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated in the description.

Referral Numerals:

Referral numeral Description
3 First bi-polar plate (Anode)
3a Upper end of the first plate
3b Lower end of the first plate
4 Second bi-polar plate (Cathode)
4a Upper end of the second plate
4b Lower end of the second plate
5 Dispensed gasket
6 Gas diffusion layer
7 First catalyst
8 Second catalyst
9 Membrane
10 Hydrogen inlet manifold
11 Hydrogen outlet manifold
12 Coolant inlet manifold
13 Coolant outlet manifold
14 Air inlet manifold
15 Air outlet manifold
16 Tapered protrusions
17 Circular protrusions
18 First sealing member
19 Second sealing member
20 Hydrogen distribution channel
21 Air distribution channel
22 Coolant flow channel
E Lanceolate protrusions
E1 Serrated dents on the lanceolate protrusions