CN113761767A - Design method for hydrogen fuel cell sealing element section taking alternating temperature influence into account - Google Patents
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- 238000007789 sealing Methods 0.000 title claims abstract description 152
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 title claims abstract description 98
- 239000001257 hydrogen Substances 0.000 title claims abstract description 98
- 229910052739 hydrogen Inorganic materials 0.000 title claims abstract description 98
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Abstract
The invention relates to a method for designing a section of a sealing element of a hydrogen fuel cell, which takes the influence of alternating temperature into account, and comprises the following steps: 1) acquiring a curve of the mechanical property of the section of the hydrogen fuel cell sealing member under different temperature conditions along with the change of time; 2) obtaining the design principle of the section of the hydrogen fuel cell sealing element according to the curve of the mechanical property changing along with the time; 3) the cross section of the hydrogen fuel cell sealing element is optimally designed by combining a design principle, and verification is carried out through finite element simulation, so that the design requirements are met. Compared with the prior art, the invention has the advantages of being close to the actual working condition, strictly designed and the like.
Description
Technical Field
The invention relates to the field of hydrogen fuel cell seal design, in particular to a hydrogen fuel cell seal section design method taking alternating temperature influence into account.
Background
With the increasing problems of environmental pollution, energy safety and the like, finding out alternative energy of fossil fuels is urgent, and hydrogen energy is regarded as future energy by people due to the characteristics of high efficiency, cleanness, economy, safety and the like. Fuel cells are the main location where hydrogen energy is released, and are the generating devices that convert internal energy into electrical energy; the method is the fourth generation technology after hydroelectric power generation, thermal power generation and atomic power generation, and is more considered as the first choice of a clean and efficient power generation mode in the 21 st century.
Hydrogen fuel cells are widely used with high power density and energy conversion efficiency, and relatively suitable operating temperatures. The hydrogen fuel cell has extremely high requirements on the internal environment during operation: the reaction gas should be maintained within a suitable pressure range; the anode gas and the cathode gas should not generate internal leakage and mutual channeling; impurities and the like cannot be present in the reaction space. Briefly, the sealing member in the hydrogen fuel cell plays an important role of 'external leakage prevention and internal blow-by prevention'.
At present, the traditional mechanical sealing theory is generally adopted as a reference when the design of the hydrogen fuel cell sealing member is carried out, but the theories are difficult to be well suitable for the sealing design of the hydrogen fuel cell; this is because the O-ring used in the conventional mechanical seal has the characteristics of simple cross-sectional shape, single ring shape, small circumference, etc., and the large circumference seal is often used in the sealing of the hydrogen fuel cell and the cross-sectional shape thereof is complicated.
In addition to being geometrically different from conventional seals, the external effects to which hydrogen fuel cell seals are subjected are also more complex: a substantially alternating operating temperature; the packaging force, the gas lateral force and the friction force act simultaneously; a chemical reaction with a reaction gas (hydrogen gas), and the like. These loads and constraints directly determine the performance and useful life of the hydrogen fuel cell seal. Among the above factors, the temperature has the most significant effect on the sealing performance of hydrogen fuel cells: the temperature directly changes the mechanical property, the size parameter and the like of the sealing element, and then changes the real compression ratio of the sealing element in a working state, thereby determining the real contact stress and the internal stress during sealing.
There are two main ways in which temperature can act on a hydrogen fuel cell seal, on the one hand, the operating temperature at which the seal is operated can directly affect the modulus of elasticity of the seal material. In a low-temperature environment, the sealing element material is hardened, and the elastic modulus is increased; in high temperature environments, the seal material "softens" and the modulus of elasticity decreases. On the other hand, after the mechanical properties of the sealing element material are changed, the number, the width and the like of the gas leakage channels are different from the states at normal temperature, and the real leakage rate of the sealing element is difficult to predict; meanwhile, the friction force, the contact state and the like of the sealing element and other components can be changed, and the actual service life of the sealing element can also show nonlinear change.
It can be seen from the above that the effect of temperature on the performance of hydrogen fuel cell seals is not negligible, and this effect will be more pronounced when the temperature is alternated. When the sealing member is in an environment with alternating temperature, the elastic deformation of the sealing member material gradually changes to the plastic deformation which can not rebound, the actual compression ratio of the sealing member continuously changes, the contact stress and the internal stress of the sealing member periodically change, and finally the sealing performance and the service life of the hydrogen fuel cell sealing member at the alternating temperature are difficult to analyze. The current sealing element design of the hydrogen fuel cell only considers the influence of single temperature (constant high temperature or constant low temperature) on the sealing performance mostly, and does not fully consider the irreversible change generated by the performance of the sealing element under the alternating temperature, so that the sealing performance of the hydrogen fuel cell is really poor, and the difference between the actual service life and the theoretical value is large.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a method for designing the section of a sealing element of a hydrogen fuel cell, which takes the influence of alternating temperature on the mechanical property of the sealing element into account.
The purpose of the invention can be realized by the following technical scheme:
a method of designing a hydrogen fuel cell seal cross-section incorporating alternating temperature effects, comprising the steps of:
1) acquiring a curve of the mechanical property of the section of the hydrogen fuel cell sealing member under different temperature conditions along with the change of time;
2) obtaining the design principle of the section of the hydrogen fuel cell sealing element according to the curve of the mechanical property changing along with the time;
3) the cross section of the hydrogen fuel cell sealing element is optimally designed by combining a design principle, and verification is carried out through finite element simulation, so that the design requirements are met.
The step 1) specifically comprises the following steps:
11) acquiring the temperature characteristics of the hydrogen fuel cell during operation, including the lowest cold start temperature and the highest working temperature;
12) setting a typical sealing member temperature working condition according to the temperature characteristic of the hydrogen fuel cell during working;
13) and obtaining mechanical parameters of the hydrogen fuel cell sealing element under various working conditions through finite element simulation.
In the step 12), typical sealing member temperature working conditions comprise a constant temperature working condition and an alternating temperature working condition.
The alternating temperature working condition is a three-cycle alternating temperature working condition as a limit working condition, and specifically comprises the following steps:
equally dividing the 24 hours into three cycles, one temperature cycle every 8 hours, each temperature cycle comprising 4 phases, then:
(1) the first 2 hours are the stage of increasing the working temperature of the hydrogen fuel cell, wherein the temperature is increased from-40 ℃ to 20 ℃ in the first hour, and the temperature is increased from 20 ℃ to 100 ℃ in the second hour;
(2) the 3 rd to 5 th hours are temperature keeping stages, and the temperature is constantly 100 ℃;
(3) the 6 th hour is a natural temperature reduction stage;
(4) the last two hours is the low temperature standing stage, and the temperature is kept at-40 ℃.
The mechanical properties are specifically as follows:
the maximum contact stress and the average internal stress generated under different temperature conditions after the hydrogen fuel cell seal member is subjected to the initial compression rate,
according to the Hertz contact theory and the rubber material service life model, the maximum contact stress is used as the mechanical expression of the sealing performance, and the average internal stress is used as the judgment basis of the service life of the sealing element.
In the step 2), the design principle of the cross section is as follows:
the sealing performance of the hydrogen fuel cell sealing element is in positive correlation with the maximum contact stress, the service life of the hydrogen fuel cell sealing element is in negative correlation with the average internal stress, the maximum contact stress is increased to enhance the sealing performance of the sealing element when the sealing element is in pressed contact, and the average internal stress is reduced to prolong the overall service life of the sealing element when the cross section is designed.
The step 3) specifically comprises the following steps:
31) obtaining a design scheme of the section of the sealing member of the initial hydrogen fuel cell;
32) modifying and optimizing the initial scheme according to an optimized modification mode corresponding to the design principle;
33) and (4) carrying out finite element simulation experiment on the optimized design scheme to obtain the mechanical characteristics under the alternating temperature working condition, if the design requirements are met, finishing the design, otherwise, returning to the step 32).
In the step 32), the optimization modification method includes:
the edge curvature is slowed down to reduce stress concentration, the arch structure is adopted to enhance stability and improve overall internal stress distribution, and the height difference of different contact areas is coordinated to realize multi-section sealing contact under the same compression.
The optimization and modification modes specifically comprise the following means:
slowing down the curvature of the edge: the curvature of the top angle of the cross section is reduced to improve the stress concentration phenomenon at the transition position of the top angle and the upper plane, and simultaneously, the better contact state of the original model can be still maintained;
and (3) changing the shape of the base angle: the bottom corners are changed from original right angles into round corners so as to effectively relieve the phenomenon of material tearing caused by stress concentration at the positions;
removing the inner space: the whole sealing element adopts an arch structure, on one hand, the structure can well improve the average internal stress distribution of the whole sealing element, so that the internal stress of each position tends to be average, and on the other hand, the support at the two ends of the arch structure can improve the posture stability of the sealing element when the sealing element is pressed;
coordinating the height difference of different areas: through the three means, the average internal stress of the sealing element is improved, the stress concentration phenomenon is avoided, the contact stress is reduced at the same time, the sealing performance is further influenced, the heights of different areas are adjusted in order to consider two mechanical indexes, the sealing performance of the sealing element is not inhibited, the real compression ratio among the areas is changed, and the average internal stress of a specific area can be effectively reduced on the premise that the contact stress is basically unchanged.
Compared with the prior art, the invention has the following advantages:
the maximum contact stress and the average internal stress of the invention are convenient to obtain, and the comparison between each mechanical parameter is direct, so that the influence of alternating temperature on the performance of the hydrogen fuel cell sealing piece is conveniently and visually discovered;
the invention sets a three-cycle alternating temperature working condition of-40 ℃ to 100 ℃, and the severe working condition of 140 ℃ temperature change range can more strictly verify the resistance of the hydrogen fuel cell sealing element to the alternating temperature and is closer to the real working condition;
the invention provides a design method of a sealing element section under an alternating temperature working condition, and the design method has theoretical reference significance for improving the sealing property and prolonging the service life of the sealing element in an alternating temperature environment.
Drawings
FIG. 1 is a flow chart demonstrating the effect of alternating temperature on hydrogen fuel cell seal performance in accordance with the present invention.
Figure 2 is a comparative hydrogen fuel cell seal dimensional model used in an example of the invention.
Fig. 3 is a dimensional model of experimental group hydrogen fuel cell seals used in an example of the invention.
Fig. 4 shows the temperature condition parameters set in the embodiment of the present invention.
FIG. 5 is a comparison of the mechanical parameters of the interface of the seal of the control group under constant temperature and alternating temperature conditions in example 1, wherein (5a) is the stress at each temperature, (5b) is the maximum contact stress as a function of temperature cycle, and (5c) is the internal stress as a function of temperature cycle.
FIG. 6 is a comparison of mechanical parameters of the cross section of the seals of the control group and the experimental group at alternating temperatures in example 2, wherein (6a) is the variation of the maximum contact stress of the seals of the control group and the experimental group at alternating temperatures, and (6b) is the variation of the stress in the seals of the control group and the experimental group at alternating temperatures.
Detailed Description
In order to make the aforementioned features and advantages of the present invention more comprehensible, to prove the effectiveness of the method according to the present invention and to briefly analyze the effect of the alternating temperature on the hydrogen fuel cell seal, the following description will be given in detail with reference to the accompanying drawings by way of specific examples.
Since the hydrogen fuel cell has the output characteristic of 'large current and small voltage', in order to meet the practical engineering use, 300-. For the whole stack system, the series characteristic determines that any one part has a problem, and the electric efficiency of the whole stack is greatly reduced and even fails and stops. Hundreds of sealing elements exist in a hydrogen fuel cell stack, the problems that the sealing elements are unstable in contact state and rapid in internal stress rise and even crack easily occur at alternating temperature, and the unstable property of the sealing elements at the alternating temperature becomes an important factor for limiting the whole stack efficiency and service life of the hydrogen fuel cell. The anode or cathode seal of each hydrogen fuel cell may be referred to as a "one-layer" seal. Due to the characteristics of different heat generation of the anode and the cathode of the hydrogen fuel cell, different heat generation of different areas, different sealing force applied to different areas, different gas pressure and the like, the actual compression ratios of different section positions of the same layer of sealing element are also different, so that the sealing performance and the degradation curve of the same layer of sealing element are also different. Based on the idea, the invention provides a hydrogen fuel cell sealing element section design method which fully accounts for the influence of alternating temperature to provide a cushion and a basis for further layer sealing and stack sealing design by changing the mechanical parameters of the hydrogen fuel cell sealing element under the alternating temperature.
The invention provides a method for designing a section of a sealing member of a hydrogen fuel cell, which takes the influence of alternating temperature into account, and comprises the following steps:
firstly, analyzing the influence of alternating temperature on the sealing performance and the service life of the sealing element by comparing the mechanical properties of the sealing element of the traditional sealing element section (a comparison group) under different temperature conditions;
then, a sealing part section design method with good resistance to alternating temperature is provided, and finite element simulation experiment verification is carried out on the novel section (experiment group).
The specific description of each step is as follows:
1) acquiring the temperature characteristics of the hydrogen fuel cell during working: the lowest cold start temperature is as low as minus 40 ℃, and the highest working temperature reaches 90 ℃;
2) setting typical sealing element temperature working conditions including a typical constant temperature working condition and an alternating temperature working condition according to the temperature characteristics of the hydrogen fuel cell during working;
3) obtaining mechanical parameters of the hydrogen fuel cell sealing element under the working conditions of constant temperature and alternating temperature by a finite element simulation experiment method, wherein the mechanical parameters specifically refer to the maximum contact stress and the average internal stress generated in different temperature environments after the hydrogen fuel cell sealing element is subjected to initial compression rate;
in the analysis of the alternating temperature working condition, the value of the mechanical parameter of the sealing element changes along with the time after being influenced by the alternating temperature under the initial compression ratio, so that the curve of the maximum contact stress and the average internal stress changing along with the time is used as the analysis basis;
according to the existing Hertz contact theory and a rubber material service life model, the maximum contact stress is the mechanical expression of the sealing performance of the sealing element, and the average internal stress is the judgment basis of the service life of the sealing element.
According to the contact mechanics theory and the rubber material aging theory, the invention considers that the sealing performance of the hydrogen fuel cell sealing element is in positive correlation with the maximum contact stress, and the service life of the hydrogen fuel cell sealing element is in negative correlation with the average internal stress.
4) When the section of the sealing element of the hydrogen fuel cell is designed, a region with a larger contact stress value is reserved to enhance the sealing property when the sealing element is in pressed contact; deleting the area with larger internal stress, optimizing the stress concentration phenomenon, reducing the average internal stress of the sealing element, and improving the overall service life of the sealing element, wherein the content of modifying and designing the comparison group model is as follows:
(1) the curvature of the top angle of the model in the comparison group is reduced, the shape of the bottom angle of the model is changed, the stress concentration phenomenon at the joint of the top angle and the top surface and the stress concentration phenomenon at the bottom angle are directly improved, and meanwhile, the contact state is ensured to be basically unchanged;
(2) the height of the vertex angle is reduced, under the condition that the integral compression ratio of the sealing element is not changed, the actual compression ratio is reduced when the heights of the two vertex angles are reduced, the average internal stress is reduced, and the contact stress at the improved vertex angle is basically unchanged and the original sealing performance is maintained through calculation;
(3) the internal space of the comparison model is removed, the experimental model with the arch structure can ensure the installation stability, balance the overall average internal stress of the sealing element, finally provide space for the shrinkage change of the sealing section under the influence of temperature, and maintain the mechanical property stability of the sealing element.
The present example describes a sealing structure of a control group hydrogen fuel cell with reference to fig. 2, which is as follows:
the hydrogen fuel cell sealing element is simultaneously contacted with the MEA frame and the BPP sealing groove, and generates compression deformation under the action of the sealing force, thereby playing a role in sealing. As shown in fig. 2, the comparison model adopted in the embodiment of the present invention is a trapezoidal seal groove, and specific parameters are shown in fig. 2. The cross section of the control group adopts a wide D shape, and the seal of the wide D shape is most widely applied to hydrogen fuel cells and has better stability, and the detailed dimensional parameters are shown in figure 2. The initial height of the sealing element is 0.57mm, the compressed height is 0.405mm, and the initial compression rate is 28.95 percent, so that the setting not only meets the requirement of the gap between the MEA and the BPP after the hydrogen fuel cell is compressed and sealed, but also can ensure that the sealing element is in the range of the proper compression rate of the rubber material.
The set alternating temperature condition in the present invention is described with reference to fig. 4, which is as follows:
the invention sets a three-cycle alternating temperature working condition, which is specifically set out in combination with fig. 4. Each temperature cycle contained 8 hours and was divided into 4 phases:
(1) the first 2 hours are the stage of increasing the working temperature of the hydrogen fuel cell, wherein the temperature is increased from-40 ℃ to 20 ℃ in the first hour, and the temperature is increased from 20 ℃ to 100 ℃ in the second hour;
(2) the 3 rd to 5 th hours are temperature keeping stages, and the temperature is constantly 100 ℃;
(3) the 6 th hour is a natural temperature drop phase, which is indicated by a dotted line in fig. 4;
(4) the last two hours is the low temperature standing stage, and the temperature is kept at-40 ℃. Three alternating temperature cycles for 24 hours constitute a complete alternating temperature regime.
Example 1
The mechanical parameters of the hydrogen fuel cell sealing member under the constant temperature and alternating temperature working conditions of the control group are analyzed by combining the accompanying figure 5, and the specific description is as follows:
in this example, a conventional wide D-type hydrogen fuel cell seal cross-section was selected as the control.
Three typical working temperatures of the hydrogen fuel cell sealing element are set, namely low temperature (-40 ℃), normal temperature (20 ℃) and high temperature (100 ℃), and the maximum contact stress is gradually reduced from low temperature to high temperature and is 4.67MPa, 3.21MPa and 1.58MPa in sequence through a computer finite element simulation experiment; the average internal stress of the sealing element has the same change trend with the maximum contact stress, and the average internal stress and the maximum contact stress of the sealing element have the same change trend and are 4.32MPa, 3.08MPa and 1.62MPa in sequence.
From the results in fig. 5 (a) and the basis for maximum contact stress reacting hydrogen cell seal type, average internal stress reacting seal life, it can be derived: the hydrogen fuel cell sealing member has the best sealing performance at the temperature of minus 40 ℃, and has the best service life at the temperature of 100 ℃. Obviously, these conclusions do not completely conform to the sealing performance and service life distribution of the sealing member of the real hydrogen fuel cell, because the mapping of the mechanical index to the specific performance is complex and non-linear, and the invention does not give detailed explanation on the generation of the error, but focuses on verifying the influence of the alternating temperature on the mechanical index of the sealing member of the hydrogen fuel cell.
By observing fig. 5b and 5c, it can be seen that the maximum contact stress gradient of the hydrogen fuel cell seal decreases and the average internal stress gradient increases after three temperature cycles. Even if the mechanical parameters of the seal can be restored to the original level during the low-temperature rest phase, it is well documented that the mechanical properties of the seal become increasingly lower than the original level with alternating temperature cycles, which is clearly different from the stable mechanical properties exhibited by the seal at constant temperature. At around 1 hour, the curve of FIG. 5 produced sharp corners due to the large fluctuations in temperature load on the seal that occurred when the first time the seal was acted on in the computer finite element simulation experiment.
Observing the values of the mechanical parameters at constant temperature and at alternating temperature in fig. 5, it can be seen that the alternating temperature not only causes the mechanical index of the sealing member to generate gradient change, but also changes the amplitude of the sealing member, the maximum contact stress of the hydrogen fuel cell sealing member in the alternating temperature environment is approximately equal to the value at normal temperature, the maximum contact stress gradually decreases as the alternating temperature begins to affect the properties of the sealing adhesive material, and the sealing gradient of the sealing member decreases under multiple cycles, which tends to approach the sealing state at high temperature. By using the same concept, the change characteristic of the internal stress of the hydrogen fuel cell sealing member at alternating temperature can be obtained.
Example 2
The mechanical parameters of the hydrogen fuel cell sealing member under the alternating temperature working condition of the control group and the experimental group are analyzed by combining the attached figure 6, and the specific description is as follows:
in this example, the design of the hydrogen fuel cell seal member cross section resistant to alternating temperature effects was completed. According to the method and the thought related by the invention, the average internal stress of the section of the novel sealing element is reduced, the contact stress distribution and the contact state during section sealing are improved, and the gradient degradation phenomenon generated by the mechanical property of the sealing element along with temperature circulation is avoided, and the specific model is shown in figure 3.
With reference to fig. 6a, it can be seen that the maximum contact stress of the hydrogen fuel cell seal section obtained by the method of the present invention at high temperature is smaller than that at low temperature, but the variation period and amplitude are more precise under the influence of the alternating temperature, and no gradient variation is present. With reference to fig. 6b, it can be similarly seen that the change in the average internal stress also becomes "well-defined and traceable", and the gradient rise is also avoided.
The method provides stable and effective guarantee for analyzing the mechanical characteristics of the cross section of the hydrogen fuel cell sealing element under the working condition of alternating temperature, and enables long-term quantitative analysis of the performance of the sealing element to be possible. The above examples, which are provided as a verification and demonstration of the method of the present invention, are a statement and subdivision of the inventive concept and are not intended to limit the invention. The protection scope of the present invention shall be subject to the claims.
In conclusion, the invention improves the sealing performance of the hydrogen fuel cell under the alternating temperature environment and the accuracy of theoretical analysis of the service life, can provide a basis for the sealing design of the hydrogen fuel cell with lower leakage and long service life, fully considers the actual alternating temperature working condition of the hydrogen fuel cell, selects the typical constant temperature working condition, designs the working condition close to the real alternating temperature working condition, and ensures the accuracy.
Claims (10)
1. A method of designing a hydrogen fuel cell seal cross-section incorporating alternating temperature effects, comprising the steps of:
1) acquiring a curve of the mechanical property of the section of the hydrogen fuel cell sealing member under different temperature conditions along with the change of time;
2) obtaining the design principle of the section of the hydrogen fuel cell sealing element according to the curve of the mechanical property changing along with the time;
3) the cross section of the hydrogen fuel cell sealing element is optimally designed by combining a design principle, and verification is carried out through finite element simulation, so that the design requirements are met.
2. A method of designing a seal cross-section of a hydrogen fuel cell according to claim 1, wherein said step 1) comprises the steps of:
11) acquiring the temperature characteristics of the hydrogen fuel cell during operation, including the lowest cold start temperature and the highest working temperature;
12) setting a typical sealing member temperature working condition according to the temperature characteristic of the hydrogen fuel cell during working;
13) and obtaining mechanical parameters of the hydrogen fuel cell sealing element under various working conditions through finite element simulation.
3. The method of claim 2, wherein in step 12), the typical seal temperature conditions include a constant temperature condition and an alternating temperature condition.
4. A method according to claim 3, wherein the alternating temperature condition is a three-cycle alternating temperature condition as a limit condition, and specifically comprises:
equally dividing the 24 hours into three cycles, one temperature cycle every 8 hours, each temperature cycle comprising 4 phases, then:
(1) the first 2 hours are the stage of increasing the working temperature of the hydrogen fuel cell, wherein the temperature is increased from-40 ℃ to 20 ℃ in the first hour, and the temperature is increased from 20 ℃ to 100 ℃ in the second hour;
(2) the 3 rd to 5 th hours are temperature keeping stages, and the temperature is constantly 100 ℃;
(3) the 6 th hour is a natural temperature reduction stage;
(4) the last two hours is the low temperature standing stage, and the temperature is kept at-40 ℃.
5. A method of designing a seal cross-section of a hydrogen fuel cell according to claim 1, wherein the mechanical properties are specifically:
maximum contact stress and average internal stress generated under different temperature conditions after the hydrogen fuel cell seal is subjected to an initial compression ratio.
6. The method as claimed in claim 5, wherein the maximum contact stress is used as the mechanical expression of the sealing performance according to the Hertz contact theory and the rubber material life model, and the average internal stress is used as the criterion for determining the life of the sealing member.
7. A method for designing a cross section of a seal member of a hydrogen fuel cell taking into account the influence of alternating temperature according to claim 6, wherein in the step 2), the design principle of the cross section is specifically as follows:
the sealing performance of the hydrogen fuel cell sealing element is in positive correlation with the maximum contact stress, the service life of the hydrogen fuel cell sealing element is in negative correlation with the average internal stress, the maximum contact stress is increased to enhance the sealing performance of the sealing element when the sealing element is in pressed contact, and the average internal stress is reduced to prolong the overall service life of the sealing element when the cross section is designed.
8. A method of designing a seal cross-section of a hydrogen fuel cell according to claim 1, wherein said step 3) comprises the following steps:
31) obtaining a design scheme of the section of the sealing member of the initial hydrogen fuel cell;
32) modifying and optimizing the initial scheme according to an optimized modification mode corresponding to the design principle;
33) and (4) carrying out finite element simulation experiment on the optimized design scheme to obtain the mechanical characteristics under the alternating temperature working condition, if the design requirements are met, finishing the design, otherwise, returning to the step 32).
9. A method of designing a seal cross-section of a hydrogen fuel cell according to claim 8, wherein said step 32) of optimizing the modification comprises:
the edge curvature is slowed down to reduce stress concentration, the arch structure is adopted to enhance stability and improve overall internal stress distribution, and the height difference of different contact areas is coordinated to realize multi-section sealing contact under the same compression.
10. A design method of a cross section of a seal member of a hydrogen fuel cell taking into account alternating temperature influence according to claim 9, wherein each optimization modification specifically includes the following means:
slowing down the curvature of the edge: the curvature of the top angle of the cross section is reduced to improve the stress concentration phenomenon at the transition position of the top angle and the upper plane, and simultaneously, the better contact state of the original model can be still maintained;
and (3) changing the shape of the base angle: the bottom corners are changed from original right angles into round corners so as to relieve the phenomenon of material tearing caused by stress concentration at the positions;
removing the inner space: the whole sealing element adopts an arch structure to improve the average internal stress distribution of the whole sealing element, so that the internal stress of each position tends to be average, and the posture stability of the sealing element under pressure can be improved by supporting two ends of the arch structure;
coordinating the height difference of different areas: the height of different areas is adjusted for the purpose of giving consideration to two mechanical indexes of stress concentration and sealing performance so that the sealing performance of the sealing element is not inhibited, the real compression ratio among the areas is changed, and the average internal stress of a specific area is effectively reduced on the premise of keeping the contact stress unchanged.
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