A method for identifying and simulating thermal decay of PEMFC electrolyte under dynamic conditions
By establishing a joint solution of the electrolyte glass conversion temperature correlation and multi-physical field coupling model, the problem that the thermal attenuation of PEMFC electrolytes is difficult to judge in real time under dynamic operating conditions, and a rapid judgment of electrolyte attenuation during operating conditions is achieved. Improve the operating status monitoring efficiency of PEMFC.
Patent Information
- Application Number
- CN202211499317.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-11-28
- Publication Date
- 2025-01-03
- Estimated Expiration
- 2042-11-28
AI Technical Summary
The prior art is difficult to judge the thermal attenuation of the proton exchange membrane fuel cell (PEMFC) electrolyte in real time under dynamic operating conditions. The degree of attenuation can only be determined by dismantling the battery after the operating conditions, and cannot be judged during operation.
By establishing a joint solution of the electrolyte glass conversion temperature correlation formula and the multi-physical coupling model of the proton exchange membrane fuel cell, the local temperature and the electrolyte glass conversion temperature under dynamic operating conditions are obtained to determine whether the electrolyte has attenuated.
It realizes real-time judgment of whether the electrolyte has thermal attenuation under dynamic operating conditions, simplifies the analysis process, avoids waiting for the attenuation determination after the operating conditions, and improves the electrolyte state monitoring efficiency during PEMFC operation.
Smart Images
Figure CN116087783B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of fuel cells, and in particular to a method for distinguishing and simulating thermal decay of a PEMFC electrolyte under dynamic conditions. Background Art
[0002] Proton exchange membrane fuel cells (PEMFC) have the advantages of zero emissions and high efficiency, and are expected to replace traditional internal combustion engines and become a new generation of automotive power source. However, cost and life issues still restrict the large-scale promotion of hydrogen fuel cell vehicles. Studies have shown that the decay rate of PEMFC under dynamic conditions is significantly faster than that under steady-state operation, among which local high temperature and temperature fluctuations are the main reasons for the rapid decay of materials. In PEMFC, the electrolyte is most significantly affected by temperature. High temperature will cause electrolyte dehydration, and in severe cases, irreversible structural deformation will occur, causing overall damage to the PEMFC.
[0003] In the current research on PEMFC electrolyte thermal decay under dynamic conditions, the degree of decay is mainly determined by disassembling the battery after the endurance condition and comparing the changes in the electrolyte structure and efficiency before and after the condition, and further analyzing the electrolyte thermal decay process by combining the electrolyte structure and efficiency performance at different temperatures. This method cannot determine the thermal decay of the electrolyte during the operating condition, and can only determine the degree of electrolyte thermal decay after the battery operation is completed.
[0004] Therefore, how to determine the occurrence of PEMFC electrolyte thermal decay during dynamic operating conditions has attracted much attention. Summary of the invention
[0005] The present invention is made to solve the above-mentioned problems, and aims to provide a method for distinguishing and simulating thermal decay of PEMFC electrolyte under dynamic conditions.
[0006] The present invention provides a method for distinguishing and simulating thermal attenuation of a PEMFC electrolyte under dynamic conditions, which has the following characteristics and comprises the following steps: step 1, obtaining an electrolyte glass transition temperature correlation equation based on the correlation between the electrolyte glass transition temperature and environmental parameters; step 2, jointly solving the electrolyte glass transition temperature correlation equation and a proton exchange membrane fuel cell multi-physical field coupling model to obtain a local temperature T under dynamic conditions and the electrolyte glass transition temperature Tg at that location; step 3, judging whether the electrolyte has decayed based on the local temperature T under dynamic conditions and the electrolyte glass transition temperature Tg at that location.
[0007] The PEMFC electrolyte thermal attenuation identification and simulation method under dynamic conditions provided by the present invention may also have the following characteristics: wherein the dynamic conditions include NEDC light vehicle conditions, heavy truck conditions and measured conditions controlled by current or voltage, and the electrolyte is an ionomer in a proton exchange membrane or a catalyst layer.
[0008] The method for distinguishing and simulating thermal attenuation of PEMFC electrolyte under dynamic conditions provided by the present invention may also have the following characteristics: wherein, in step 1, the environmental parameters include humidity, temperature, water content and pressure.
[0009] The method for distinguishing and simulating thermal attenuation of PEMFC electrolyte under dynamic conditions provided by the present invention may also have the following characteristics: wherein, in step 1, the electrolyte glass transition temperature correlation equation is obtained by theoretical calculation, deductive hypothesis or experimental device experiment, and the experimental device is any one or more of a thermal analyzer, a constant temperature and humidity chamber and an AC impedance device.
[0010] The PEMFC electrolyte thermal attenuation identification and simulation method under dynamic conditions provided by the present invention may also have the following characteristics: wherein, in step 2, the electrolyte glass transition temperature correlation equation is a correlation equation between the glass transition temperature and external variables, and the external variables include humidity, temperature, water content and pressure.
[0011] In the PEMFC electrolyte thermal attenuation judgment and simulation method under dynamic conditions provided by the present invention, it can also have the following characteristics: wherein, in step 2, the proton exchange membrane fuel cell multi-physical field coupling model includes one-dimensional, two-dimensional and three-dimensional PEMFC full-cell steady-state and transient models, and the multi-physical fields include temperature field, anode hydrogen concentration field, anode water vapor concentration field, cathode oxygen concentration field, cathode nitrogen concentration field, cathode water vapor concentration field, gas-liquid two-phase flow velocity field, gas-liquid two-phase flow pressure field, membrane water concentration field, electron electric field and hydrogen ion electric field.
[0012] In the PEMFC electrolyte thermal attenuation judgment and simulation method under dynamic conditions provided by the present invention, it can also have the following characteristics: wherein, in step 2, the process of joint solution is: combining the glass transition temperature correlation equation with the proton exchange membrane fuel cell multi-physical field coupling model, and then obtaining the spatiotemporal distribution of the multi-physical fields in the proton exchange membrane fuel cell by a numerical solution method, and the implementation method of the numerical solution method is any one or more of FluentAnsys, COMSOL, Matlab and C++.
[0013] The PEMFC electrolyte thermal attenuation identification and simulation method under dynamic conditions provided by the present invention may also have the following characteristics: wherein, in step 3, the local temperature T includes the temperature of the interface between the two functional layers of the proton exchange membrane and the catalyst layer and any area in the bulk phase.
[0014] The method for distinguishing and simulating thermal decay of PEMFC electrolyte under dynamic conditions provided by the present invention may also have the following characteristics: wherein, in step 3, the electrolyte glass transition temperature Tg is a characteristic parameter of thermal decay of the electrolyte.
[0015] In the method for discriminating and simulating the thermal degradation of the PEMFC electrolyte under dynamic conditions provided by the present invention, it may further have the following characteristics: Among them, in step 3, the method for determining whether the electrolyte has degraded is: if T>Tg, the electrolyte has undergone thermal degradation; if T<Tg, the electrolyte has not undergone thermal degradation.
[0016] Functions and effects of the invention
[0017] According to the method for discriminating and simulating the thermal degradation of the PEMFC electrolyte under dynamic conditions involved in the present invention, the specific process is as follows: Step 1, obtain the correlation formula of the electrolyte glass transition temperature according to the correlation between the electrolyte glass transition temperature and environmental parameters; Step 2,联立 solve the electrolyte glass transition temperature correlation formula with the multi-physical field coupling model of the proton exchange membrane fuel cell to obtain the local temperature T and the electrolyte glass transition temperature Tg at that place under dynamic conditions; Step 3, determine whether the electrolyte has degraded according to the local temperature T and the electrolyte glass transition temperature Tg at that place under dynamic conditions.
[0018] Therefore, the method for obtaining the determination method of the thermal degradation of the PEMFC electrolyte under dynamic conditions provided by the present invention determines whether the electrolyte has undergone thermal degradation by simulating the electrolyte glass transition temperature and the surrounding temperature under dynamic conditions. Compared with the method of disassembling the battery and isolation testing in the prior art to determine the thermal degradation of the electrolyte, this technical solution can determine the possibility of the electrolyte undergoing thermal degradation during the operation of the working condition, and realizes the determination of whether the electrolyte has undergone thermal degradation during the operation of the PEMFC. Brief description of the drawings
[0019] Figure 1 It is the flow chart of the method for obtaining the determination and modeling of the thermal degradation of the PEMFC electrolyte under dynamic conditions in Embodiment 1 of the present invention;
[0020] Figure 2 It is the flow chart of the method for obtaining the determination and modeling of the thermal degradation of the PEMFC electrolyte under dynamic conditions in Embodiment 2 of the present invention;
[0021] Figure 3 It is the correlation diagram of the Ionomer glass transition temperature (Tg) and the membrane water content (λ) obtained based on experiments and linear assumptions in Embodiment 2 of the present invention;
[0022] Figure 4 It is the transient one-dimensional model diagram constructed by联立 solving the Tg-λ correlation formula with the PEMFC multi-physical field coupling model in Embodiment 2 of the present invention;
[0023] Figure 5 It is the dynamic condition diagram of the current-controlled NEDC light vehicle in Embodiment 2 of the present invention;
[0024] Figure 6It is a dynamic curve diagram of the cathode catalyst layer surface temperature (T) and the ionomer glass transition temperature (Tg) at the dynamic working condition obtained by numerical calculation based on the joint transient model in Example 2 of the present invention. DETAILED DESCRIPTION
[0025] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the following embodiment, combined with the accompanying drawings, specifically describes the PEMFC electrolyte thermal attenuation judgment and simulation method under a dynamic working condition of the present invention.
[0026] <Example 1>
[0027] In this embodiment, a method for distinguishing and simulating thermal decay of PEMFC electrolyte under dynamic conditions is provided, which can understand the internal electrolyte state of PEMFC under dynamic conditions, determine whether thermal decay occurs, and simplify the thermal decay analysis process of PEMFC electrolyte under dynamic conditions, wherein the dynamic conditions include NEDC light vehicle conditions controlled by current or voltage, heavy truck conditions, and measured conditions.
[0028] Figure 1 This is a flow chart of the method for determining and modeling the thermal decay of the PEMFC electrolyte under dynamic conditions obtained in Example 1.
[0029] like Figure 1 As shown, the PEMFC electrolyte thermal decay identification and simulation method under dynamic conditions involved in this embodiment includes the following steps:
[0030] Step S1, obtaining an electrolyte glass transition temperature correlation equation based on the correlation between the electrolyte glass transition temperature and environmental parameters.
[0031] In this embodiment, the electrolyte includes a proton exchange membrane and an ionomer in the catalyst layer. The correlation between the electrolyte glass transition temperature and the environmental parameters can be obtained by experiment, or by theoretical calculation or conjecture. In this embodiment, the correlation between the electrolyte glass transition temperature and the environmental parameters is obtained by experimental measurement.
[0032] In this embodiment, the environmental parameters include humidity, temperature, water content and pressure.
[0033] Step S2, jointly solving the electrolyte glass transition temperature correlation equation and the proton exchange membrane fuel cell (PEMFC) multi-physics field coupling model to obtain the local temperature T under dynamic conditions and the electrolyte glass transition temperature Tg at that location.
[0034] In this embodiment, the electrolyte glass transition temperature correlation equation is a correlation equation between the glass transition temperature and humidity, temperature, water content and pressure.
[0035] The way of simultaneous solution can be taking the correlation as the input parameter of the multi-physical field coupling model, or as the coupled sub-model. The PEMFC multi-physical field coupling model includes a steady-state model and a transient model. In this embodiment, the way of simultaneous solution is taking the correlation as the coupled sub-model of the multi-physical field coupling model.
[0036] The multi-physical fields in this embodiment include temperature field, anode hydrogen concentration field, anode nitrogen concentration field, cathode oxygen concentration field, cathode water vapor concentration field, gas-liquid two-phase flow velocity field, gas-liquid two-phase flow pressure field, membrane water concentration field, electron electric field and hydrogen ion electric field.
[0037] Step S3, judge whether the electrolyte decays according to the local temperature T and the electrolyte glass transition temperature Tg under dynamic working conditions.
[0038] In this embodiment, the way of obtaining the working conditions can be given manually or obtained through the battery management system. In this embodiment, the way of obtaining the working conditions is obtained through the battery management system. The local temperature is the temperature of the proton exchange membrane and the catalyst layer. In addition, which specific PEMFC multi-physical field coupling model to adopt is determined according to the working conditions.
[0039] The electrolyte glass transition temperature Tg is the characteristic parameter for the thermal decay of the electrolyte. The method for judging whether the electrolyte decays is as follows:
[0040] If T>Tg, the electrolyte undergoes thermal decay; if T<Tg, the electrolyte does not undergo thermal decay.
[0041] The method for determining and simulating the thermal decay of the PEMFC electrolyte under dynamic working conditions disclosed in this embodiment determines whether the electrolyte undergoes thermal decay by the battery electrolyte glass transition temperature and the ambient temperature. Compared with the method of disassembling the battery and combining isolation tests in the prior art, once the ambient temperature is higher than the electrolyte glass transition temperature, it can simply and quickly judge that the electrolyte undergoes thermal decay, and converts the thermal decay criterion into the relative magnitude of two temperatures, realizing the rapid judgment of the thermal decay of the PEMFC electrolyte under dynamic working conditions.
[0042] <Example 2>
[0043] The main reason for the irreversible thermal decay of the ionomer is the change in the structure and performance of the electrolyte caused by high temperature. When the ambient temperature is higher than the glass transition temperature, the ionomer will undergo structural relaxation, and the stability and mechanical properties of the membrane will decline. Usually, the glass transition temperature (Tg) is used as the characteristic parameter for the thermodynamic transition of the electrolyte structural relaxation. In this embodiment, by simulating the dynamic response of the electrolyte glass transition temperature and the local temperature under dynamic working conditions, the relative magnitudes of the two are compared to judge whether the ionomer undergoes thermal decay.
[0044] Figure 2 This is a flow chart of the method for determining and modeling the thermal decay of the PEMFC electrolyte under dynamic conditions obtained in Example 2.
[0045] like Figure 2 As shown, the specific steps for obtaining are:
[0046] Step S1, obtaining a correlation equation between the ionomer glass transition temperature (Tg) and the membrane water content (λ) in the catalyst layer through experimental data and linear assumptions.
[0047] Figure 3 This is a correlation diagram between the ionomer glass transition temperature (Tg) and the film water content (λ) obtained in Example 2 based on experiments and linear assumptions.
[0048] like Figure 3 As shown, the Tg-λ correlation can be obtained through experimental data and linear assumption.
[0049] Figure 4 It is a transient one-dimensional model diagram constructed based on the Tg-λ correlation formula and the PEMFC multi-physical field coupling model in this embodiment 2.
[0050] Step S2, first establish a PEMFC multi-physics field coupled one-dimensional transient model to obtain the spatiotemporal distribution of the temperature (T) in the battery and the membrane water content (λ) in the electrolyte, such as Figure 4 As shown, Figure 3 The Tg-λ correlation and the PEMFC multi-physics field coupled one-dimensional transient model are solved jointly, and the dynamic response of Tg is obtained based on the dynamic response of λ.
[0051] Step S3, based on the model, obtain the dynamic response data of the cathode catalyst layer surface temperature (T) and the ionomer glass transition temperature under dynamic conditions, and determine whether the ionomer at this location has thermal decay according to the size of T and Tg.
[0052] Figure 5 This is the current-controlled NEDC light vehicle dynamic operating condition diagram in this embodiment 2.
[0053] like Figure 5 As shown, the current-controlled NEDC light vehicle operating condition map is used as the transient model input in step S2, and the dynamic response curves of the local temperature in the battery and the electrolyte glass transition temperature are obtained by numerical calculation.
[0054] Figure 6 It is a dynamic curve diagram of the cathode catalyst layer surface temperature (T) and the ionomer glass transition temperature (Tg) at the dynamic working condition obtained by numerical calculation based on the joint transient model in this embodiment 2.
[0055] like Figure 6 As shown in the figure, it can be found that during the high-speed operation stage, the ambient temperature (T) will be higher than the ionomer glass transition temperature (Tg), which can be judged that the ionomer undergoes thermal decay at this time.
[0056] Functions and Effects of the Embodiments
[0057] According to the PEMFC electrolyte thermal attenuation identification and simulation method under dynamic conditions involved in this embodiment, the specific process is as follows: Step 1, based on the correlation between the electrolyte glass transition temperature and the environmental parameters, the electrolyte glass transition temperature correlation formula is obtained; Step 2, the electrolyte glass transition temperature correlation formula and the proton exchange membrane fuel cell multi-physical field coupling model are jointly solved to obtain the local temperature T under dynamic conditions and the electrolyte glass transition temperature Tg at that location; Step 3, based on the local temperature T under dynamic conditions and the electrolyte glass transition temperature Tg at that location, it is determined whether the electrolyte has decayed.
[0058] Therefore, this embodiment provides a method for determining thermal decay of the PEMFC electrolyte under dynamic conditions, which determines whether thermal decay of the electrolyte occurs by simulating the electrolyte glass transition temperature and the ambient temperature under dynamic conditions. Compared with the prior art method of determining thermal decay of the electrolyte by disassembling the battery and performing isolation testing, this technical solution can determine the possibility of thermal decay of the electrolyte during the operating process, thereby realizing the determination of whether thermal decay of the electrolyte occurs during the operation of the PEMFC.
[0059] The above-mentioned embodiments are preferred examples of the present invention and are not intended to limit the protection scope of the present invention.
Claims
1. A method for identifying and simulating thermal decay of PEMFC electrolyte under dynamic conditions, characterized in that: The following steps are involved: Step 1, obtaining a correlation formula of electrolyte glass transition temperature according to the correlation between electrolyte glass transition temperature and environmental parameters; Step 2, jointly solving the electrolyte glass transition temperature correlation equation and the proton exchange membrane fuel cell multi-physics field coupling model to obtain the local temperature T and the electrolyte glass transition temperature Tg at the location under dynamic conditions; Step 3: Determine whether the electrolyte is attenuated based on the local temperature T under the dynamic condition and the electrolyte glass transition temperature Tg at that location.
2. The method for distinguishing and simulating thermal attenuation of PEMFC electrolyte under dynamic conditions according to claim 1, characterized in that: in, The dynamic operating conditions include NEDC light vehicle operating conditions, heavy truck operating conditions and actual measured operating conditions controlled by current or voltage. The electrolyte is a proton exchange membrane or an ionomer in a catalyst layer.
3. The method for distinguishing and simulating thermal attenuation of PEMFC electrolyte under dynamic conditions according to claim 1, characterized in that: in, In step 1, the environmental parameters include humidity, temperature, water content and pressure.
4. The method for distinguishing and simulating thermal attenuation of PEMFC electrolyte under dynamic conditions according to claim 1, characterized in that: in, In step 1, the electrolyte glass transition temperature correlation equation is obtained by theoretical calculation, deduction hypothesis or experiment with an experimental device. The experimental device is any one or more of a thermal analyzer, a constant temperature and humidity chamber, and an AC impedance device.
5. The method for distinguishing and simulating thermal decay of PEMFC electrolyte under dynamic conditions according to claim 1, characterized in that: in, In step 2, the electrolyte glass transition temperature correlation equation is a correlation equation between the glass transition temperature and external variables, The external variables include humidity, temperature, water content and pressure.
6. The method for distinguishing and simulating thermal attenuation of PEMFC electrolyte under dynamic conditions according to claim 1, characterized in that: in, In step 2, the multi-physics field coupling model of the proton exchange membrane fuel cell includes one-dimensional, two-dimensional and three-dimensional PEMFC full-cell steady-state and transient models. The multi-physical fields include temperature field, anode hydrogen concentration field, anode water vapor concentration field, cathode oxygen concentration field, cathode nitrogen concentration field, cathode water vapor concentration field, gas-liquid two-phase flow velocity field, gas-liquid two-phase flow pressure field, membrane water concentration field, electron electric field and hydrogen ion electric field.
7. The method for distinguishing and simulating thermal decay of PEMFC electrolyte under dynamic conditions according to claim 1, characterized in that: in, In step 2, the process of the joint solution is: establishing the proton exchange membrane fuel cell multi-physical field coupling model, obtaining the spatiotemporal distribution of the multi-physical fields in the proton exchange membrane fuel cell of the battery temperature T and the electrolyte membrane water content λ, jointly solving the Tg-λ correlation equation and the proton exchange membrane fuel cell multi-physical field coupling model, and obtaining the dynamic response of Tg based on the dynamic response of λ.
8. The method for distinguishing and simulating thermal decay of PEMFC electrolyte under dynamic conditions according to claim 1, characterized in that: in, In step 3, the local temperature T includes the temperature of the interface between the two functional layers of the proton exchange membrane and the catalyst layer and any region in the bulk phase.
9. The dynamic operating condition-based PEMFC electrolyte thermal decay discrimination and simulation method according to claim 1, characterized in that: in, In step 3, the electrolyte glass transition temperature Tg is a characteristic parameter for the electrolyte to undergo thermal decay.
10. The dynamic operating condition-based PEMFC electrolyte thermal decay discrimination and simulation method according to claim 1, characterized in that: in, In step 3, the method for determining whether the electrolyte has decayed is as follows: If T > Tg, the electrolyte undergoes thermal decay; if T < Tg, the electrolyte has not undergone thermal decay.