Proton exchange membrane fuel cell polarization condition optimization method

Abstract

The invention belongs to the technical field of fuel cells, and particularly provides a proton exchange membrane fuel cell polarization condition optimization method, which comprises the following steps: 1) carrying out a polarization test to obtain polarization test data; 2) drawing a polarization curve; 3) calculating an average value # imgabs0 # of voltage values corresponding to current points Ik in the upper polarization curve and the lower polarization curve; 4) outputting a new working condition when Uk-U'k meets a target value; otherwise, entering step 5); 5) obtaining current values Ix and Iy corresponding to the average value # imgabs1 # of the voltage values in the upper polarization curve and the lower polarization curve, and 6) finding new test parameter values corresponding to the current values Ix and Iy in the upper polarization curve and the lower polarization curve according to the current density corresponding to the current point Ik; 7) obtaining new test parameter values of all current points in the current value I, and performing the polarization test again; and 8) obtaining a required polarization curve until all current points in the current value I meet the condition of outputting a new working condition. The problem of large difference between the existing upper and lower polarization curves is solved; the polarization curves are small in difference and smaller in error.

Description

Technical Field

[0001] The invention belongs to the technical field of fuel cells, and in particular relates to a method for optimizing polarization conditions of proton exchange membrane fuel cells. Background Art

[0002] Proton exchange membrane fuel cell (PEMFC) is an efficient and clean energy conversion device with the characteristics of cleanliness, high efficiency and low noise. Polarization test is a direct method to evaluate the performance of PEMFC. It reflects the performance of the fuel cell stack by measuring the voltage output of the fuel cell stack at different current densities. Polarization test can reveal the key information that affects the performance output of the fuel cell stack, such as power generation performance, consistency and internal resistance, and then optimize the design and operating conditions of the fuel cell and improve the performance and stability of the fuel cell stack. Therefore, determining a more reasonable polarization condition is crucial to improving the overall performance of the fuel cell stack.

[0003] At present, the polarization conditions in the industry are often set by technicians according to the design conditions and modified according to the test experience. The polarization curves obtained in this way will have obvious differences when performing "upward polarization" (polarization process of gradually increasing current from OCV to high current point) and "downward polarization" (polarization process of gradually decreasing current from high current point to OCV), which is not conducive to the best performance of fuel cells. Therefore, it will have a great impact on the actual performance definition of fuel cell stacks and technical exchanges in the same industry.

[0004] As fuel cell technology develops towards greater power and more precise control, the use of reasonable methods to eliminate the differentiation of polarization curves will be increasingly valued by R&D personnel and enterprises. This patent proposes a method for optimizing the polarization conditions of proton exchange membrane fuel cells based on polarization parameter difference analysis. By comparing and analyzing the "upper polarization" and "lower polarization" parameters of the fuel cell and jointly solving them, a smoother and more stable polarization curve with a smaller degree of difference can be obtained, which has positive significance for the precise and standardized testing of fuel cells.

[0005] A Chinese patent document with publication number CN116505038A discloses a method for optimizing the performance of a fuel cell, which includes: obtaining the first optimization parameter of a single fuel cell in a stack; optimizing the first optimization parameter based on environmental data under different operating environments and a preset genetic algorithm to obtain the optimal parameter value of the first optimization parameter under different operating environments; determining the polarization curve of the fuel cell under different operating environments based on the optimal parameter value of the first optimization parameter under different operating environments, wherein the polarization curve is a three-segment function curve of voltage with respect to current density; updating and iterating the parameter value of the second optimization parameter of the stack based on a preset flow network algorithm until the preset flow distribution condition is met, outputting the optimal flow distribution coefficient of the stack; determining the optimization result of the stack based on the optimal flow distribution coefficient and the polarization curve under different operating environments. This document solves the problem of uneven flow distribution of fuel cell stacks. It does not solve the problem of large differences in "upper and lower polarization". Summary of the invention

[0006] The present invention provides a method for optimizing polarization conditions of a proton exchange membrane fuel cell, aiming to overcome the problem of large difference between upper and lower polarization curves in the prior art.

[0007] To this end, the present invention provides a method for optimizing polarization conditions of a proton exchange membrane fuel cell, comprising the following steps:

[0008] 1) performing a polarization test according to the design operating conditions of the fuel cell stack to obtain polarization test data; the polarization test data includes a current value I at an upper polarization condition point, an average voltage value U at an upper polarization condition point, a current value I' at a lower polarization condition point, and an average voltage value U' at a lower polarization condition point;

[0009] 2) Draw the upper polarization curve and the lower polarization curve according to the polarization test data;

[0010] 3) Take the current point I in both the upper polarization curve and the lower polarization curve k , find the corresponding voltage value U in the upper polarization curve k , find the corresponding voltage value U' in the lower polarization curve k , calculate the current point I in the upper polarization curve and the lower polarization curve k The average value of the corresponding voltage

[0011] 4) When |U k- U' k |When the target value is met, output the new working condition; otherwise, go to step 5);

[0012] 5) Obtain the average voltage value in the upper polarization curve The corresponding current value I x , take the average voltage value in the lower polarization curve The corresponding current value I y ;

[0013] 6) According to the current point I k Corresponding current density, find the current value I in the upper polarization curve x The corresponding test parameter values ​​and the current value I in the lower polarization curve y The corresponding test parameter value is based on the current value I x Corresponding test parameter value and current value I y The corresponding test parameter value is the current point I k New test parameter values;

[0014] 7) Repeat steps 3) to 6) to obtain new test parameter values ​​for all current points in the current value I, and perform polarization test again using the new test parameter values ​​for the current value I;

[0015] 8) Repeat steps 2) to 7) until all current points in the current value I meet the conditions for outputting the new working condition in step 4) to obtain the desired polarization curve.

[0016] Preferably, the

[0017] Preferably, in step 4), when |U k- U' k |≤5mv, output new working condition.

[0018] Preferably, the step 6) is based on the current point I k The corresponding current density is obtained by linearly taking the current value I in the upper polarization curve. x The corresponding test parameter value is used to find the current value I in the lower polarization curve by linear value selection. y The corresponding test parameter value.

[0019] Preferably, the current value I x Corresponding test parameter value and current value I y The corresponding average value of the test parameter is the current point I k The new test parameter value.

[0020] Preferably, the test parameters include intake air temperature, cooling water inlet temperature, and intake air pressure.

[0021] Preferably, when the current point I k The corresponding current density J k ∈[0.1,0.4]A / cm 2 When the current point I k The new intake air temperature.

[0022] Preferably, when Ik The corresponding current density J k ∈[0.5,1.4]A / cm 2 When the current point I k The new intake air temperature and the new cooling water inlet temperature.

[0023] Preferably, when I k The corresponding current density J k >1.4A / cm 2 When the current point I k The new intake air temperature, new cooling water inlet temperature and new intake air pressure.

[0024] Beneficial effects of the present invention:

[0025] 1. The method for optimizing the polarization working condition of a proton exchange membrane fuel cell provided by the present invention comprises the following steps: the polarization curve obtained by steps 1) to 8) has all current points in the current value I satisfying the new working condition output in step 4), that is, |U k- U' k |≤5mv, the error of the polarization curve is smaller, which can better show the actual energy output of the fuel cell stack at each operating point, so that scientific researchers can better and more accurately adjust and optimize the fuel cell; it is convenient for technical exchanges to use unified standards and operating conditions to compare the performance of existing fuel cell products.

[0026] 2. The method for optimizing polarization conditions of proton exchange membrane fuel cells provided by the present invention obtains polarization curves through steps 1) to 8), and the smaller "upper and lower polarization" errors make the polarization test results more reliable, and the test can be completed in a shorter time, thereby reducing the waste of electrical energy, hydrogen and manpower during the test process, and saving a large amount of hydrogen and electricity resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention will be further described in detail below with reference to the accompanying drawings.

[0028] Figure 1 It is a schematic flow diagram of a method for optimizing polarization conditions of a proton exchange membrane fuel cell;

[0029] Figure 2 This is the first polarization curve diagram of Example 2;

[0030] Figure 3 This is the second polarization curve diagram of Example 2;

[0031] Figure 4 This is the third polarization curve diagram of Example 2. DETAILED DESCRIPTION

[0032] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0033] Embodiment 1:

[0034] like Figure 1 As shown, a method for optimizing polarization conditions of a proton exchange membrane fuel cell comprises the following steps:

[0035] 1) performing a polarization test according to the design operating conditions of the fuel cell stack to obtain polarization test data; the polarization test data includes a current value I at an upper polarization condition point, an average voltage value U at an upper polarization condition point, a current value I' at a lower polarization condition point, and an average voltage value U' at a lower polarization condition point;

[0036] Specifically, the current value I (denoted as I0, I1, I2, I3, ... I n ), the average voltage value U of the upper polarization condition point (denoted as U0, U1, U2, U3, ... U n ); the current value I' of the lower polarization condition point (denoted as I'0, I'1, I'2, I'3, ... I' n ), the average voltage value of the lower polarization condition point U' (denoted as U'0, U'1, U'2, U'3, ... U' n );

[0037] 2) Draw the upper polarization curve and the lower polarization curve according to the polarization test data;

[0038] 3) Take the current point I in both the upper polarization curve and the lower polarization curve k , find the corresponding voltage value U in the upper polarization curve k , find the corresponding voltage value U' in the lower polarization curve k , calculate the current point I in the upper polarization curve and the lower polarization curve k The average value of the corresponding voltage

[0039] Preferably, the

[0040] 4) When |U k- U' k |When the target value is met, output the new working condition; otherwise, go to step 5);

[0041] Preferably, in step 4), when |U k- U' k |≤5mv, output new working condition.

[0042] 5) Obtain the average voltage value in the upper polarization curve The corresponding current value Ix , take the average voltage value in the lower polarization curve The corresponding current value I y( Let I x <I y) ;

[0043] 6) According to the current point I k Corresponding current density, find the current value I in the upper polarization curve x The corresponding test parameter values ​​and the current value I in the lower polarization curve y The corresponding test parameter value is based on the current value I x Corresponding test parameter value and current value I y The corresponding test parameter value is the current point I k New test parameter values;

[0044] Preferably, the current value I x Corresponding test parameter value and current value I y The corresponding average value of the test parameter is the current point I k The new test parameter value.

[0045] Preferably, the current point I k The corresponding current density is obtained by linearly taking the current value I in the upper polarization curve. x The corresponding test parameter value is used to find the current value I in the lower polarization curve by linear value selection. y The corresponding test parameter value.

[0046] Preferably, the test parameters include intake air temperature, cooling water inlet temperature, and intake air pressure.

[0047] Preferably, when the current point I k The corresponding current density J k ∈[0.1,0.4]A / cm 2 When the current point I k The new intake air temperature.

[0048] Specifically, when the current point I k The corresponding current density J k ∈[0.1,0.4]A / cm 2 When the current value I in the upper polarization curve is found by linear value selection x Corresponding intake temperature (hydrogen and air) T' x , and the current value I in the lower polarization curve y Corresponding intake temperature (hydrogen and air) T' y , and get the current point I k The new intake air temperature

[0049] Preferably, when I k The corresponding current density J k ∈[0.5,1.4]A / cm 2 When the current point I k The new intake air temperature and the new cooling water inlet temperature.

[0050] Specifically, when I k The corresponding current density J k ∈[0.5,1.4]A / cm 2 When the current value I in the upper polarization curve is found by linear value selection x Corresponding intake temperature (hydrogen and air) T' x and the corresponding cooling water inlet temperature T″ x , and the current value I in the lower polarization curve y Corresponding intake temperature (hydrogen and air) T' y and the corresponding cooling water inlet temperature T″ y , and get the current point I k The new intake air temperature and the new cooling water inlet temperature

[0051] Preferably, when I k The corresponding current density J k >1.4A / cm 2 When the current point I k The new intake air temperature, new cooling water inlet temperature and new intake air pressure.

[0052] Specifically, when I k The corresponding current density J k >1.4A / cm 2 When the current value I in the upper polarization curve is found by linear value selection x Corresponding intake temperature (hydrogen and air) T' x , corresponding cooling water inlet temperature T″ x and the corresponding intake pressure (hydrogen and air) P x , and the current value I in the lower polarization curve y Corresponding intake temperature (hydrogen and air) T' y , corresponding cooling water inlet temperature T″ y and the corresponding intake pressure (hydrogen and air) P y , and get the current point I k The new intake air temperature New cooling water inlet temperature and intake pressure

[0053] 7) Repeat steps 3) to 6) to obtain all current points (I1, I2, I3, ... I n-1 The polarization test is performed again using the new test parameter value of the current value I;

[0054] 8) Repeat steps 2) to 7) until all current points in the current value I meet the conditions for outputting the new working condition in step 4), that is, |U1-U'1|, |U2-U'2|, |U3-U'3|, ... |U n-1 -U' n-1 |, if any of the values ​​is ≤5mv, the required polarization curve is obtained.

[0055] The polarization curve obtained by this method greatly reduces the difference between "upper and lower polarization", and the error of the polarization curve is smaller, which can better show the actual energy output of the fuel cell stack at each operating point, so that scientific researchers can better and more accurately adjust and optimize the fuel cell; it is convenient for technical exchanges to use unified standards and operating conditions to compare the performance of existing fuel cell products.

[0056] The polarization curve obtained by this method has a smaller "upper and lower polarization" error, which makes the polarization test result more reliable and can complete the test in a shorter time, thereby reducing the waste of electrical energy, hydrogen and manpower in the test process and saving a lot of hydrogen and electricity resources.

[0057] Embodiment 2:

[0058] Based on Example 1, a method for optimizing polarization conditions of a proton exchange membrane fuel cell comprises the following steps:

[0059] 1) Carry out polarization test according to the design working condition of fuel cell stack to obtain polarization test data; the polarization test data includes the current value I (0A, 25A, 50A, 75A, 100A, 125A, 150A, 175A, 200A, 225A, 250A, 275A, 300A, 325A, 350A, 375A, 400A, 425 A, 450A), the average voltage value U of the upper polarization condition point (0.953V, 0.846V, 0.817V, 0.802V, 0.786V, 0.770V, 0.758V, 0.746V, 0.737V, 0.730V, 0.723V, 0.715V, 0.706V, 0.700V, 0.692V, 0.685V, 0. 675V, 0.666V, 0.659V), the current value I' (0A, 25A, 50A, 75A, 100A, 125A, 150A, 175A, 200A, 225A, 250A, 275A, 300A, 325A, 350A, 375A, 400A, 425A, 450A) and the average voltage value of the lower polarization condition point U'(0.956V, 0.853V, 0.824V, 0.808V, 0.793V, 0.780V, 0.768V, 0.756V, 0.748V, 0. 740V, 0.734V, 0.726V, 0.719V, 0.711V, 0.702V, 0.691V, 0.680V, ​​0.671V, 0.659V);

[0060] 2) Draw the upper polarization curve and the lower polarization curve according to the polarization test data;

[0061] 3) Taking a current point of 25A in both the upper polarization curve and the lower polarization curve, the average voltage value corresponding to the current point 25A in the upper polarization curve and the lower polarization curve is obtained, which is 0.8495V;

[0062] 4) |0.846-0.853|=0.007v=7mv>5mv, go to step 5);

[0063] 5) The current values ​​corresponding to U = 0.8495 V are Ix = 24.79 A and Iy = 25.13 A on the two polarization curves;

[0064] 6) Take the linear value of the condition parameter at the 25A current point to obtain the hydrogen inlet temperature T' x is 43.3℃, ​​T′ y The temperature of hydrogen inlet is 43.5℃, and the temperature of hydrogen inlet is T' 25A is 43.4℃; similarly, the air inlet T′ is obtained 25A 43.5℃;

[0065] 7) By analogy, new battery stack polarization test parameters are obtained; polarization test is performed using the new battery stack polarization test parameters, and graphing is performed;

[0066] 8) Obtain the non-compliant current points 125A, 300A, and 375A, and obtain the average voltages of the three points as 0.7745V, 0.7132V, and 0.6927V, and obtain the new operating parameters (new test parameters) of the three points as follows:

[0067] The current density at the current point of 125A is 0.5A / cm 2 ;

[0068] Hydrogen inlet temperature T' 125A is 44.2℃, air inlet temperature T' 125A The cooling inlet temperature is 44.4℃, T″ 125A 60.2℃;

[0069] The current density at the current point of 300A is 1.2A / cm 2 ;

[0070] Hydrogen inlet temperature T' 300A is 53.8℃, air inlet temperature T' 300A The cooling inlet temperature is 55.1℃, T″ 300A is 70.3℃;

[0071] The current density at the current point 375A is 1.5A / cm 2 ;

[0072] Hydrogen inlet temperature T' 375A is 55.5℃, air inlet temperature T' 375A The cooling inlet temperature is 52.1℃, T″ 375A is 71.8℃, hydrogen inlet pressure P 375 is 144.6kPa, air inlet pressure P 375 123.9 kPa;

[0073] The polarization test was performed again using the new operating parameters. After comparing the various operating points of the polarization curve, the voltage difference was less than 5mV, and the test was completed. Figure 2-Figure 4 The polarization curves obtained from three tests.

[0074] from Figure 2-Figure 4 As we know, after multiple optimizations, the difference between the upper and lower polarization curves is greatly reduced.

[0075] The above examples are merely illustrative of the present invention and do not constitute a limitation on the protection scope of the present invention. All designs that are the same or similar to the present invention fall within the protection scope of the present invention.

Claims

1. A method for optimizing polarization conditions of a proton exchange membrane fuel cell, characterized in that: The steps include: 1) performing a polarization test according to the design operating conditions of the fuel cell stack to obtain polarization test data; the polarization test data includes a current value I at an upper polarization condition point, an average voltage value U at an upper polarization condition point, a current value I' at a lower polarization condition point, and an average voltage value U' at a lower polarization condition point; 2) Draw the upper polarization curve and the lower polarization curve according to the polarization test data; 3) Take the current point I in both the upper polarization curve and the lower polarization curve k , find the corresponding voltage value U in the upper polarization curve k , find the corresponding voltage value U in the lower polarization curve ’ k , calculate the current point I in the upper polarization curve and the lower polarization curve k The average value of the corresponding voltage 4) When |U k- U ’ k |When the target value is met, output the new working condition; Otherwise, go to step 5); 5) Obtain the average voltage value in the upper polarization curve The corresponding current value I x , take the average voltage value in the lower polarization curve The corresponding current value I y； 6) According to the current point I k Corresponding current density, find the current value I in the upper polarization curve x The corresponding test parameter values ​​and the current value I in the lower polarization curve y The corresponding test parameter value is based on the current value I x Corresponding test parameter value and current value I y The corresponding test parameter value is the current point I k New test parameter values; 7) Repeat steps 3) to 6) to obtain new test parameter values ​​for all current points in the current value I, and perform polarization test again using the new test parameter values ​​for the current value I; 8) Repeat steps 2) to 7) until all current points in the current value I meet the conditions for outputting the new working condition in step 4) to obtain the desired polarization curve.

2. The method for optimizing polarization conditions of a proton exchange membrane fuel cell according to claim 1, characterized in that: Said 3. The method for optimizing polarization conditions of a proton exchange membrane fuel cell according to claim 1, characterized in that: In the step 4), when |U k- U ’ k |≤5mv, output new working condition.

4. The method for optimizing polarization conditions of a proton exchange membrane fuel cell according to claim 1, characterized in that: The step 6) is based on the current point I k The corresponding current density is obtained by linearly taking the current value I in the upper polarization curve. x The corresponding test parameter value is used to find the current value I in the lower polarization curve by linear value selection. y The corresponding test parameter value.

5. The method for optimizing polarization conditions of a proton exchange membrane fuel cell according to claim 1, characterized in that: The current value I x Corresponding test parameter value and current value I y The corresponding average value of the test parameter is the current point I k The new test parameter value.

6. The method for optimizing polarization conditions of a proton exchange membrane fuel cell according to claim 5, characterized in that: The test parameters include intake air temperature, cooling water inlet temperature, and intake air pressure.

7. The method for optimizing polarization conditions of a proton exchange membrane fuel cell according to claim 6, characterized in that: When the current point I k The corresponding current density J k ∈[0.1,0.4]A / cm 2 When the current point I k The new intake air temperature.

8. The method for optimizing polarization conditions of a proton exchange membrane fuel cell according to claim 6, characterized in that: When I k The corresponding current density J k ∈[0.5,1.4]A / cm 2 When the current point I k The new intake air temperature and the new cooling water inlet temperature.

9. The method for optimizing polarization conditions of a proton exchange membrane fuel cell according to claim 6, characterized in that: When I k The corresponding current density J k >1.4A / cm 2 When the current point I k The new intake air temperature, new cooling water inlet temperature and new intake air pressure.

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