Proton exchange membrane fuel cell bipolar plate variable-period variable-cross-section flow channel and bipolar plate

Abstract

The utility model provides a proton exchange membrane fuel cell bipolar plate variable period variable cross-section runner and bipolar plate, including bipolar plate, the runner of bipolar plate includes ridge and groove that are arranged at interval, the ridge at the both sides of same groove is symmetrically arranged along the central line of groove, the both side walls of groove are variable period wave shape, and the ridge is in the variable period wave shape. A bipolar plate runner periodically shrinks and expands in the reaction gas flowing direction, the center line of a groove serves as the x axis, the transverse fluctuation amplitude y of the side wall of the single side of the groove meets the function y = A * sin (Bx + C) + D, A, C and D are all constants, the period # imgabs0 # meets the curvilinear function # imgabs1 # k based on the Sigmoid function, m, n and q are all constants, and the symmetrical opposite side walls meet the function y '=-y. By adopting the variable-period variable-cross-section flow channel, the shrinkage cycle period of the outlet side flow channel is prevented from being too small, the reaction gas flow stability of the inlet section and the outlet section is improved, the flow speed and the pressure can be adjusted in the flow channel, the under-ridge mass transfer capacity is enhanced, the better liquid water discharge effect is achieved, and water logging is prevented.

Description

Technical Field

[0001] The utility model relates to the technical field of proton exchange membrane hydrogen fuel cell systems, and in particular to a variable-period and variable-section flow channel and a bipolar plate of a proton exchange membrane fuel cell bipolar plate. Background Art

[0002] A proton exchange membrane hydrogen fuel cell is a power generation device that uses hydrogen as fuel. Hydrogen generates water and electricity through electrochemical reactions. The smallest component unit that completes the electrochemical reaction in a fuel cell is called a single cell, which is composed of an anode plate, a membrane electrode, and a cathode plate. The bipolar plate composed of the anode plate and the cathode plate is one of the core components of the fuel cell, which plays the role of supporting the membrane electrode, providing reaction gas and coolant flow channels, and conducting charge and heat. Common bipolar plates are spliced ​​by one anode plate and one cathode plate. The outside of the anode plate has a hydrogen flow field, the outside of the cathode plate has an air flow field, and the two plates form a coolant flow field. The outer flow field area of ​​the anode and cathode corresponds to the active area on the membrane electrode, which is an important area for generating electrochemical reactions. The design of the flow channel determines the flow state of the reaction gas in the flow field. Reasonable flow channel design can ensure that the electrochemical reaction can proceed normally and improve the mass transfer efficiency of the reactants. At the same time, the water of the reaction product is discharged from the flow field in time, thereby improving the performance of the fuel cell. At present, the most common flow channels are parallel flow channels, including straight flow channels, serpentine flow channels, S-shaped flow channels, etc.

[0003] The straight-through flow channel has a simple structure and is easy to process. The flow channel is short, and the flow resistance and pressure drop are small. However, the reaction gas has a short residence time in the straight flow channel and the gas utilization rate is low. At the same time, the air flow in the flow channel is mostly laminar, lacking longitudinal gas exchange, which is not conducive to the transfer of the reaction gas to the diffusion layer. Although the existing wavy sidewall structure can improve the gas mass transfer efficiency, it will form a large flow resistance and pressure drop, which is not conducive to the discharge of liquid water. At the same time, it also requires a compressor with a higher pressure ratio, resulting in power loss.

[0004] Therefore, the inventors believe that it is necessary to optimize the traditional flow channel, increase the mass transfer effect under the ridge, and make it have a better liquid water discharge effect to prevent flooding and improve the performance of the fuel cell. Utility Model Content

[0005] In view of the defects in the prior art, the purpose of the utility model is to provide a proton exchange membrane fuel cell bipolar plate with a variable period and variable cross-section flow channel and a bipolar plate.

[0006] According to the utility model, a proton exchange membrane fuel cell bipolar plate variable-period variable-section flow channel includes a bipolar plate, wherein the flow channel of the bipolar plate includes ridges and grooves arranged at intervals, the ridges on both sides of the same groove are symmetrically arranged along the center line of the groove, and the two side walls of the groove are variable-period wavy. The bipolar plate flow channel periodically contracts and expands along the flow direction of the reaction gas. With the center line of the groove as the x-axis, the lateral fluctuation amplitude y of the single-side side wall of the groove satisfies the function y=A·sin(Bx+C)+D, A, C, and D are all constants, and the period thereof is Satisfies the curve function based on the Sigmoid function k, m, n, q are all constants, and the symmetrical opposite side walls satisfy the function y′=-y.

[0007] Preferably, the period It can also satisfy B=kx+t, where k and t are constants.

[0008] Preferably, the depth of the groove is 0.15 mm.

[0009] Preferably, the width of the groove is between 0.14 mm and 0.26 mm.

[0010] Preferably, the bipolar plate includes a metal bipolar plate, a graphite bipolar plate or a composite material bipolar plate.

[0011] Preferably, the bottom of the bipolar plate flow channel is a plane, and the bottoms of all the grooves are located on the same horizontal plane.

[0012] Preferably, the top surface of the ridges of the bipolar plate flow channel is a plane, and the top surfaces of all ridges are located in the same horizontal plane.

[0013] According to a bipolar plate provided by the utility model, the above-mentioned proton exchange membrane fuel cell bipolar plate variable period and variable cross-section flow channel is adopted.

[0014] Compared with the prior art, the utility model has the following beneficial effects:

[0015] The utility model adopts a flow channel with variable period and variable cross-section, and can optimize the variable period parameter control curve in detail according to the liquid water generation characteristics of the fuel cell. The initial section has a slow change rate, presents an approximate constant function, and the flow channel contraction cycle period is approximately equal to the period. The middle section has a rapid increase in the change rate, and the flow channel contraction cycle period decreases rapidly. The tail section has a gradual decrease in the change rate until it presents an approximate constant function again, and the flow channel contraction cycle period is again approximately equal to the period. Such a design is conducive to the transition of design features, and at the same time prevents the outlet side flow channel contraction cycle period from being too small, thereby increasing the reaction gas flow stability of the inlet section and the outlet section. Due to the change of the cross-section in the flow direction, the flow velocity and pressure can be adjusted in the flow channel, the mass transfer capacity under the ridge can be enhanced, and the liquid water discharge effect can be better, thereby preventing flooding and improving the performance of the fuel cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Other features, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0017] Figure 1 This is a top view of a variable-period and variable-section flow channel of a bipolar plate of a proton exchange membrane fuel cell, which is mainly embodied in the utility model;

[0018] Figure 2 This is a partial enlarged view of the variable period and variable cross-section flow channel of the bipolar plate of the proton exchange membrane fuel cell mainly embodied in the utility model;

[0019] Figure 3 The utility model mainly reflects the nonlinear change curve of the parameter characteristics of the flow channel variable period.

[0020] Reference numerals:

[0021] Ridge 1 Groove 2 DETAILED DESCRIPTION

[0022] The utility model is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the utility model, but do not limit the utility model in any form. It should be pointed out that for those of ordinary skill in the art, several changes and improvements can be made without departing from the concept of the utility model. These all belong to the protection scope of the utility model.

[0023] Example 1

[0024] like Figure 1-3 As shown, a proton exchange membrane fuel cell bipolar plate variable-period variable-section flow channel provided by the utility model includes a bipolar plate, the flow channel of the bipolar plate includes ridges 1 and grooves 2 arranged at intervals, the ridges 1 on both sides of the same groove 2 are symmetrically arranged along the center line of the groove 2, and the two side walls of the groove 2 are variable-period wave-shaped, and the bipolar plate flow channel periodically contracts and expands along the flow direction of the reaction gas. With the center line of the groove 2 as the x-axis, the lateral fluctuation amplitude y of the single-side side wall of the groove 2 satisfies the sine (or cosine) function y=A·sin(Bx+C)+D, A, C, and D are all constants, and the period thereof is Satisfies the curve function based on the Sigmoid function k, m, n, q are all constants, and the symmetrical opposite side walls satisfy the function y ′ =-y.

[0025] The flow channel of the bipolar plate is composed of ridges 1 and grooves 2, and a concave groove is formed between two adjacent ridges 1, so that the reaction gas flows therein. In the bipolar plate flow channel of the present application, the groove sidewall is a continuous cyclic wave shape, and the flow channel walls on both sides of the same flow channel are symmetrical to each other along the center line of the flow channel and periodically contract and expand along the flow direction of the reaction gas (i.e., from the inlet end to the outlet end), and the period is continuously variable according to the parameter characteristic curve.

[0026] The variable cross-section feature on the inlet side of the flow channel is relatively gentle. Since the water content on the cathode inlet side is relatively low, a too strong variable cross-section feature is not needed to discharge liquid water. At the same time (compared to the middle and rear sections of the flow channel), the flow resistance of this part is reduced, allowing the reaction gas to pass quickly, which is more conducive to the water management of the self-humidifying fuel cell stack.

[0027] As the flow channel extends, the reaction gas flow rate decreases and the humidity increases, and liquid water gradually generates and gathers at the middle and rear ends of the flow channel. It is necessary to reduce the cycle period of the flow channel contraction feature to make the variable cross-section feature more intense. The resulting frequency of speed and pressure changes along the flow direction becomes higher, so as to bring the liquid water in the membrane electrode out of the flow channel as soon as possible to prevent the stack from being flooded.

[0028] This application is explained by taking the following data as an example. The depth of the groove 2 of the bipolar plate flow channel is 0.15 mm. The width of the groove 2 of the bipolar plate flow channel is between 0.14 mm (contraction) and 0.26 mm (expansion). In practical applications, it can be adjusted as required without limitation. The bipolar plate includes a metal bipolar plate, a graphite bipolar plate or a composite bipolar plate.

[0029] The bottom of the bipolar plate flow channel is a plane, and the bottoms of all the grooves 2 are located at the same horizontal plane. The top surface of the ridge 1 of the bipolar plate flow channel is a plane, and the top surfaces of all the ridges 1 are located at the same horizontal plane.

[0030] Figure 3 The nonlinear change curve of the parameter characteristic of the flow channel variable period is shown in the following figure: the change rate of the initial section is relatively slow, presenting an approximate constant function, and the flow channel contraction cycle is approximately equal to the period; the change rate of the middle section rises rapidly, and the flow channel contraction cycle decreases rapidly; the change rate of the tail section gradually decreases until it presents an approximate constant function again, and the flow channel contraction cycle is approximately equal to the period again. Such a design is conducive to the transition of design features, while preventing the outlet side flow channel contraction cycle from being too small, and increasing the reaction gas flow stability of the inlet and outlet sections.

[0031] The flow channel variable period parameter curve can be adjusted according to specific needs, such as linear change and nonlinear change, different change slopes and different nonlinear change curves. For example, change the value range of k, m, n, q, increase or decrease the length of the low change rate interval of the inlet section and the outlet section, increase or decrease the amplitude of the cycle change of the middle section; or replace the above nonlinear change curve function B with a linear function, such as B = kx + t (k, t are constants).

[0032] By adopting a flow channel with variable period and variable cross-section, the present application can optimize the variable period parameter control curve in detail according to the liquid water generation characteristics of the fuel cell. Due to the change of the cross-section in the flow direction, the flow velocity and pressure can be adjusted in the flow channel, the mass transfer capacity under the ridge can be enhanced, and the liquid water discharge effect can be better, thereby preventing flooding and improving the performance of the fuel cell.

[0033] Example 2

[0034] According to a bipolar plate provided by the utility model, the variable-period and variable-section flow channel of the proton exchange membrane fuel cell bipolar plate of Example 1 is adopted.

[0035] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0036] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other at will.

Claims

1. A variable period and variable cross-section flow channel of a bipolar plate of a proton exchange membrane fuel cell, characterized in that: The invention comprises a bipolar plate, wherein the flow channel of the bipolar plate comprises ridges (1) and grooves (2) arranged at intervals, the ridges (1) on both sides of the same groove (2) are symmetrically arranged along the center line of the groove (2), the two side walls of the groove (2) are in a variable period wave shape, the bipolar plate flow channel periodically contracts and expands along the flow direction of the reaction gas, the center line of the groove is taken as the x-axis, the lateral fluctuation amplitude y of the single side wall of the groove (2) satisfies the function y=A·sin(Bx+C)+D, A, C, D are all constants, and the period thereof is Satisfies the curve function based on the Sigmoid function k, m, n, q are all constants, and the symmetrical opposite side walls satisfy the function y ′ =-y.

2. The variable period and variable cross-section flow channel of the bipolar plate of a proton exchange membrane fuel cell according to claim 1, characterized in that: cycle It can also satisfy B=kx+t, where k and t are constants.

3. The variable period and variable cross-section flow channel of the bipolar plate of a proton exchange membrane fuel cell according to claim 1, characterized in that: The depth of the groove (2) is 0.15 mm.

4. The variable period and variable cross-section flow channel of the bipolar plate of a proton exchange membrane fuel cell according to claim 1, characterized in that: The width of the groove (2) is between 0.14 mm and 0.26 mm.

5. The variable period and variable cross-section flow channel of the bipolar plate of a proton exchange membrane fuel cell according to claim 1, characterized in that: The bipolar plate includes a metal bipolar plate, a graphite bipolar plate or a composite material bipolar plate.

6. The variable period and variable cross-section flow channel of the bipolar plate of a proton exchange membrane fuel cell according to claim 1, characterized in that: The bottom of the bipolar plate flow channel is a plane, and the bottoms of all the grooves (2) are located on the same horizontal plane.

7. The variable period and variable cross-section flow channel of the bipolar plate of a proton exchange membrane fuel cell according to claim 1, characterized in that: The top surface of the ridge (1) of the bipolar plate flow channel is a plane, and the top surfaces of all the ridges (1) are located on the same horizontal plane.

8. A bipolar plate, characterized in that: A proton exchange membrane fuel cell bipolar plate with a variable period and variable cross-section flow channel as described in any one of claims 1 to 7 is adopted.

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