CN216389471U

CN216389471U - Proton exchange membrane fuel cell stack

Info

Publication number: CN216389471U
Application number: CN202123149506.3U
Authority: CN
Inventors: 侯向理; 余丽; 时丕宏; 裴昱; 徐震
Original assignee: Nekson Power Technology Co ltd
Current assignee: Nekson Power Technology Co ltd
Priority date: 2021-12-15
Filing date: 2021-12-15
Publication date: 2022-04-26
Anticipated expiration: 2031-12-15

Abstract

The utility model relates to a proton exchange membrane fuel cell stack, which comprises a stack and end plates at two ends, wherein the stack comprises a plurality of stacked single cells, and the flow of cooling medium channels of a plurality of single cells close to the end plates is 10-100% smaller than that of the cooling medium channels of the rest single cells. The utility model solves the problem of edge effect at the positions of two ends of the galvanic pile close to the end plate by changing the heat dissipation flow field structures of a plurality of single cells at the front end and the rear end of the galvanic pile, so that the temperature distribution of the galvanic pile is more uniform, the performance of the single cells at the front end and the rear end of the galvanic pile close to the end plate is improved, the power density of the whole pile is further improved, and the situations of performance reduction and service life reduction of the galvanic pile caused by the edge effect are reduced.

Description

Proton exchange membrane fuel cell stack

Technical Field

The utility model relates to the technical field of fuel cells, in particular to a proton exchange membrane fuel cell stack.

Background

A Proton Exchange Membrane Fuel Cell (PEMFC) is a device that directly converts free energy of a chemical reaction into electric energy through an electrode-electrolyte system, and the electrochemical reaction of the PEMFC is actually a process of generating water by reacting H2 and O2, and during the reaction, the temperature of a stack is gradually increased by continuously releasing heat from the PEMFC. Along with the continuous rising of the temperature of the electric pile, the electrochemical reaction rate is also continuously promoted, and meanwhile, the conductivity of the proton exchange membrane is continuously increased. Because the temperature has a significant influence on the performance of the fuel cell stack, the fuel cell stack is only in a specific temperature range, the specific temperature of each single cell of the stack keeps high uniformity, the variance and the deviation of the voltage of each single cell of the stack are kept in a certain range, and each single cell can exert the optimal performance only in the whole stack within the specified working temperature range.

The proton exchange membrane fuel cell leads to lower single cell temperature close to the end plate of the electric pile due to the inevitable heat exchange phenomenon between the end plate and the environment, the heat dissipating capacity of two sides is higher than that of the middle part, the temperature and the performance of the electric pile are enabled to show the trend that the two sides gradually increase towards the middle part, the temperature of a plurality of electric piles close to the front end and the rear end of the end plate is lower, and therefore the edge effect of the electric pile can be caused, and the performance of the electric pile is reduced, namely the edge effect of the electric pile of the fuel cell.

The traditional scheme for solving the edge effect comprises the steps of directly heating an end plate of a modern automobile, adding a false battery to a Toyota automobile and the like, wherein the direct heating of the end plate can increase the temperature of low-temperature regions at two ends of a galvanic pile, but increases the energy consumption and the control complexity of the system; the increase of the dummy cell can increase the volume and the weight of the electric pile and reduce the power density of the electric pile. Therefore, there is a need in the art for a solution to the edge effect that is simpler in structure.

SUMMERY OF THE UTILITY MODEL

The present invention is directed to a proton exchange membrane fuel cell stack that overcomes the above-mentioned shortcomings of the prior art.

In order to achieve the object of the present invention, the present application provides the following technical solutions.

In a first aspect, the present application provides a proton exchange membrane fuel cell stack comprising a plurality of stacked unit cells and end plates at both ends, wherein the flow rate of a cooling medium channel of a plurality of unit cells adjacent to an end plate is 10% to 100% smaller than the flow rate of the cooling medium channel of the remaining unit cells. This application is through reducing the flow of the coolant medium passageway of a plurality of monocells that are close to the end plate to make the heat dissipation capacity reduce, solve the edge effect of galvanic pile, thereby improve the whole heap temperature distribution homogeneity of galvanic pile, improve front and back end tablet monocell voltage, strengthen the power density of whole heap, increase the performance and the life-span of fuel cell galvanic pile.

In one embodiment of the first aspect, when the cooling medium channels of the plurality of unit cells close to the end plate are parallel straight channels, the channel depth of the channels is reduced by 10% to 100% from the channel depth of the cooling medium channels of the remaining unit cells, and the channel width and ridge width of the cooling medium channels of the plurality of unit cells close to the end plate are the same as the channel width and ridge width of the cooling medium channels of the remaining unit cells. By reducing the groove depth, the volume of the cooling medium channel is reduced, the flux of the heat dissipation medium passing through the heat dissipation flow field is reduced, and the heat dissipation capacity is reduced.

In one embodiment of the first aspect, the cooling medium passages of the plurality of unit cells adjacent to the end plate are parallel-folded flow passages. By changing the parallel straight flow channel into the parallel folding flow channel, the flow resistance of the cooling medium flowing through the folding flow channel is increased, the flow speed is reduced, the flux (namely the flow) of the cooling medium is reduced, and the heat dissipation capacity is reduced.

In one embodiment of the first aspect, the flow rate of the cooling medium passage in the 1 st to 3 rd unit cells adjacent to the end plate is 10% to 100% smaller than the flow rate of the cooling medium passage in the remaining unit cells. The specific number is confirmed as the case may be, but each of the single cells that reduce the flow rate is changed in size uniformly.

In one embodiment of the first aspect, the flow rate of the cooling medium channels of the plurality of unit cells close to the end plate is 10% to 30% smaller than the flow rate of the cooling medium channels of the remaining unit cells.

In one embodiment of the first aspect, the flow rate of the cooling medium channels of several unit cells near the end plate is 20% smaller than the flow rate of the cooling medium channels of the remaining unit cells.

Compared with the prior art, the utility model has the beneficial effects that:

(1) the provided method for solving the edge effect of the proton exchange membrane fuel cell stack can achieve the aim without additional auxiliary devices or equipment;

(2) the provided method for solving the edge effect of the proton exchange membrane fuel cell stack can be flexibly adjusted for the galvanic stacks with different sizes, the percentage of groove depth reduction is determined according to the effective active area of the galvanic stacks, and the coverage range of the groove depth reduction is 10-100%; the heat dissipation flow field is confirmed according to different sizes of the galvanic pile, and the method can be universally used for various proton exchange membrane fuel cells.

(3) The provided method for solving the edge effect of the proton exchange membrane fuel cell stack does not need to replace any raw material of a heat dissipation flow field, but can effectively reduce the heat dissipation capacity at two ends of the stack, improve the temperature uniformity of the stack and enhance the performance of the stack.

Drawings

FIG. 1 is a comparison graph of the first and last slot depths of the stack heat dissipation flow field structure of examples 1 and 2 before and after changing;

fig. 2 is a temperature comparison graph of 5 single cells at the front end, the middle part and the rear end of the air-cooled galvanic pile provided in example 1, after the groove depths of the first and the last heat dissipation flow field of the air-cooled galvanic pile are reduced by 0%, 20% and 30%;

fig. 3 is a graph comparing the performance of the first single cell of the air-cooled stack after the groove depth of the first heat dissipation flow field of the air-cooled stack is reduced by 0%, 20% and 30% in example 1;

FIG. 4 is a graph comparing the performance of the last single cell of the air-cooled stack after the groove depth of the last heat dissipation flow field of the air-cooled stack is reduced by 0%, 20% and 30% according to example 1

Fig. 5 is a graph comparing the performance of the first single cell of the liquid-cooled electric pile after the groove depth of the first heat dissipation flow field of the liquid-cooled electric pile is reduced by 0%, 20% and 30%;

fig. 6 is a graph comparing the performance of the last single cell of the liquid-cooled electric pile after the groove depth of the last heat dissipation flow field of the electric pile is reduced by 0%, 20% and 30%;

fig. 7 is a comparison diagram of the change of the first and last heat dissipation flow field channels of the liquid-cooled electric pile provided in example 3;

fig. 8 is a comparison graph of the temperature of each single cell after the first and last heat dissipation flow field structures of the liquid-cooled electric pile provided in example 3 are changed.

Detailed Description

Unless otherwise defined, technical or scientific terms used herein in the specification and claims should have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. All numerical values recited herein as between the lowest value and the highest value are intended to mean all values between the lowest value and the highest value in increments of one unit when there is more than two units difference between the lowest value and the highest value.

While specific embodiments of the utility model will be described below, it should be noted that in the course of the detailed description of these embodiments, in order to provide a concise and concise description, all features of an actual implementation may not be described in detail. Modifications and substitutions to the embodiments of the present invention may be made by those skilled in the art without departing from the spirit and scope of the present invention, and the resulting embodiments are within the scope of the present invention.

The utility model solves the problem of edge effect of the end plate parts close to the two ends of the electric pile by changing the heat dissipation flow field structures of the plurality of single cells at the front and the rear ends of the electric pile, so that the heat dissipation capacity of the plurality of single cells at the front and the rear ends of the electric pile is reduced, the edge effect of the electric pile is solved, the temperature distribution uniformity of the whole electric pile is improved, the voltage of the plurality of single cells at the front and the rear ends is improved, the power density of the whole pile is enhanced, and the performance and the service life of the fuel cell electric pile are improved.

In order to solve the problems, the utility model adopts the following technical scheme: by changing the stack heat dissipation flow field structure of the proton exchange membrane fuel cell, the widths and the ridge widths of a plurality of single-cell heat dissipation flow field grooves of the stack close to the end plate are unchanged, the groove depth of the heat dissipation flow field is reduced, the flow resistance of the heat dissipation flow field is changed, the flux of a heat dissipation medium passing through the heat dissipation flow field is reduced, and the heat dissipation capacity is reduced;

the structure and the distribution area shape of the heat dissipation flow field can be redesigned, so that the flux of a heat dissipation medium passing through the heat dissipation flow field is reduced, and the heat dissipation capacity is reduced.

The coverage range of the reduction of the depth of the electric pile groove is 10% -100%, and the specific depth is confirmed according to the effective active area of the electric pile, the volume of a heat dissipation channel and the heat dissipation capacity.

The processing mode of the pile heat dissipation flow field is kept unchanged, and the pile heat dissipation flow field can be prepared by numerical control machine processing, mould pressing or stamping casting.

The processing material of the electric pile heat dissipation flow field is unchanged.

Examples

The following will describe in detail the embodiments of the present invention, which are implemented on the premise of the technical solution of the present invention, and the detailed embodiments and the specific operation procedures are given, but the scope of the present invention is not limited to the following embodiments.

Example 1

A method for addressing edge effects in a pem fuel cell stack, comprising the acts of: taking 3 air-cooled fuel cell stacks with basically the same performance, respectively reducing the groove depths of a first radiating groove and a last radiating groove of the stack by 0%, 20% and 30%, as shown in figure 1, and then using a multi-path temperature tester to take 5 single cells at each position of the front end, the middle part and the rear end of the stack to test the temperature of the single cells; the performance of the first and last pieces of the stack was tested using a stack testing station, and the results are shown in fig. 2 to 4.

It can be seen from fig. 2 that when the depth of the heat dissipation groove is reduced, the temperature change at the middle position is not large, the temperatures at the front end and the rear end are increased, when the groove depth is reduced by 30%, the heat dissipation amount is too small, and the temperatures at the two ends of the stack are higher than the temperature at the middle of the stack; when the groove depth is reduced by 20%, the heat dissipation capacity at the two ends of the galvanic pile is reduced, the temperature rises, the temperature at the two ends of the galvanic pile is basically equal to that at the middle part, and the uniformity of the temperature distribution is better.

It can be seen from fig. 3 and 4 that the temperature changes after the groove depth is reduced, which has a certain effect on the performance of the stack, and the performance of the stack is enhanced after the temperature is increased, but an optimal temperature is provided, i.e. the temperature at the two ends of the stack is kept with the temperature at the middle part, the first and the last pieces of the stack have the best performance, i.e. the temperature distribution uniformity and the best performance of the air-cooled stack are achieved when the groove depth is reduced by 20%.

Example 2

A method for addressing edge effects in a pem fuel cell stack, comprising the acts of: taking 3 liquid-cooled fuel cell stacks with basically the same performance, then reducing the groove depth of the first and the last radiating grooves of the stacks by 0%, 20% and 30% respectively, and then adopting the same test method as the example 1, and the results are shown in fig. 5 and 6.

It can be seen from fig. 5 and 6 that when the groove depth is reduced, the temperature of the first and last liquid-cooled stacks is increased due to the reduction of the heat dissipation amount, and the performance of the stacks is significantly increased. The performance of reducing the groove depth by 20 percent is better than that of the electric pile of reducing the groove depth by 30 percent, namely the temperature distribution uniformity of the liquid-cooled electric pile is the best and the performance is the best when the groove depth is reduced by 20 percent.

Example 3

A method for addressing edge effects in a pem fuel cell stack, comprising the acts of: taking 2 liquid-cooled fuel cell stacks with basically the same performance, then redesigning the structures of the first and last heat dissipation flow fields of one of the liquid-cooled fuel cell stacks, and changing the structure of the other heat dissipation flow field into a parallel folded flow field without changing the structure as shown in fig. 7, namely changing the heat dissipation flow field from the original parallel straight flow field into the parallel folded flow field. The same test method as in example 1 was then used, and the results are shown in FIG. 8. As can be seen from fig. 8, the flow resistance of the heat dissipation flow field is increased after the shape of the flow channel is changed, so that the flux speed of the heat dissipation medium passing through the heat dissipation flow field is reduced, the heat dissipation capacity is reduced, the temperature of the single cell at the two ends of the stack close to the end plate is increased, the temperature at the middle part of the stack is basically kept unchanged, and the fluctuation of the overall temperature curve of the stack is small after the structure of the flow channel is changed. The liquid-cooled electric pile changes the structure of the first and the last heat dissipation flow field flow channel, so that the problem of the edge effect of the electric pile can be effectively solved.

The embodiments described above are intended to facilitate the understanding and appreciation of the application by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present application is not limited to the embodiments herein, and those skilled in the art who have the benefit of this disclosure will appreciate that many modifications and variations are possible within the scope of the present application without departing from the scope and spirit of the present application.

Claims

1. A proton exchange membrane fuel cell stack comprises a stack and end plates at two ends, wherein the stack comprises a plurality of stacked single cells, and the flow of a cooling medium channel of a plurality of single cells close to the end plates is 10-100% smaller than that of the cooling medium channels of the rest single cells.

2. The pem fuel cell stack of claim 1 wherein, when the coolant channels of the cells adjacent to the end plates are parallel straight channels, the channels have a groove depth reduced by 10% to 100% from the groove depth of the coolant channels of the remaining cells, and the width of the coolant channels and ridges of the cells adjacent to the end plates are the same as the width of the coolant channels and ridges of the remaining cells.

3. The pem fuel cell stack of claim 1 wherein the coolant channels of the individual cells adjacent the end plates are parallel folded channels.

4. The pem fuel cell stack of claim 1 wherein the flow rate of the coolant channels in the 1 st to 3 rd cells adjacent to the end plates is 10% to 100% less than the flow rate of the coolant channels in the remaining cells.

5. The PEM fuel cell stack according to any one of claims 1-4 wherein the coolant channels of a plurality of cells adjacent to the end plate have a flow rate 10-30% less than the flow rate of the coolant channels of the remaining cells.

6. The pem fuel cell stack of claim 5 wherein the coolant passages of a number of cells adjacent the end plates have a flow rate that is 20% less than the flow rate of the coolant passages of the remaining cells.