A life prediction method for marine fuel cells

Abstract

The present invention provides a life prediction method for a marine fuel cell, which belongs to the field of fuel cell technology and solves the problem that the prior art cannot accurately predict the life of a marine fuel cell. The method comprises: obtaining actual marine operating condition data, and obtaining a reference operating condition of the ship's required power after processing; dividing the reference operating condition into a number of sub-intervals, and converting the ship's required power in each sub-interval into the output power of the marine fuel cell according to the energy management strategy to obtain a marine basic operating condition; converting the marine basic operating condition into an accelerated operating condition for a rapid life test; performing a rapid life test on the marine fuel cell according to the accelerated operating condition to obtain an accelerated life of the marine fuel cell; determining an acceleration factor according to the marine basic operating condition and the accelerated operating condition, and obtaining the actual service life of the marine fuel cell in combination with the accelerated life. The method is suitable for scientific prediction of the service life of fuel cells when hydrogen fuel cells are used as a power source in hybrid ship power.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a life prediction method for marine fuel cells. Background Art

[0002] In order to achieve the dual carbon goals of energy conservation, emission reduction and green environmental protection, marine fuel cells are gradually gaining popularity. Compared with the requirements of automotive hydrogen fuel cells, marine fuel cells are required to have a longer service life, higher power and stability.

[0003] At present, the life prediction method of marine fuel cells is still imperfect. The life of marine fuel cells is closely related to the use conditions, which are very different from the use conditions of automotive fuel cells. Most of the existing fuel cell life prediction methods are for automotive fuel cells, and are not suitable for marine fuel cells, such as the solutions recorded in Chinese patents CN110749825B and CN111007402B.

[0004] In summary, it is not possible to directly apply the life prediction method of automotive fuel cells to evaluate the life of marine fuel cells, which may result in significantly different evaluation results. Life is an important technical indicator of ship power, and the existing technology lacks a reliable life prediction method for marine fuel cells. Summary of the invention

[0005] In view of the above analysis, an embodiment of the present invention aims to provide a method for predicting the life of a marine fuel cell, so as to solve the problem that the prior art cannot accurately predict the life of a marine fuel cell.

[0006] On the one hand, an embodiment of the present invention provides a life prediction method for a marine fuel cell, comprising the following steps:

[0007] S1. Acquire actual ship operating condition data and obtain reference operating conditions of ship power requirements after processing;

[0008] S2. Divide the reference operating condition into several sub-intervals, and convert the ship demand power in each sub-interval into the output power of the marine fuel cell according to the energy management strategy to obtain the marine basic operating condition;

[0009] S3. Convert the marine basic working condition into the accelerated working condition for rapid life test;

[0010] S4. Conduct rapid activation and stability tests on the tested fuel cell stack of the marine fuel cell, determine the current density reference point for monitoring the fuel cell stack performance degradation, and the operating conditions when the test is completed;

[0011] S5. Perform a rapid life test on the marine fuel cell according to the above-mentioned accelerated operating conditions and current density reference point and the operating conditions when the test is completed to obtain the accelerated life of the marine fuel cell;

[0012] S6. Determine the acceleration factor according to the basic marine operating conditions and the accelerated operating conditions, and obtain the actual service life of the marine fuel cell in combination with the above-mentioned accelerated life.

[0013] The beneficial effects of the above technical solution are as follows: a method for quickly evaluating the life of marine fuel cells based on actual ship operating conditions is provided, which includes the formulation of working conditions for rapid life tests and life test evaluation. It is suitable for scientific prediction of the service life of fuel cells when hydrogen fuel cells are used as the power source in hybrid ship propulsion, saving experimental costs and R&D cycles. This method fills the gap in the current lack of relevant life assessment methods in the industry, and provides support and effective basis for the development of fuel cells in the field of ship applications.

[0014] Based on the further improvement of the above method, step S1 further includes the following sub-steps:

[0015] S11. Obtaining actual marine operating data;

[0016] S12. Determine the curve of the change of ship power demand with operation time according to the actual ship operating condition data;

[0017] S13. Data processing of the curve of the change of the ship's power demand over the running time, including identification of characteristic operating conditions and segmentation according to characteristic operating conditions; the characteristic operating conditions include arrival at the port, departure from the port, acceleration, deceleration, load change, high-speed navigation and low-speed navigation;

[0018] S14. From the data processing results, select the change curve segments whose number of characteristic working conditions exceeds the first set value and whose types exceed the second set value to form a reference working condition.

[0019] Furthermore, the characteristic operating conditions covered by the reference operating conditions include arrival at the port, departure from the port, acceleration, deceleration, load change, high-speed navigation and low-speed navigation.

[0020] Further, step S2 includes the following sub-steps:

[0021] S21. According to the energy management allocation principle, the reference operating condition is divided into several sub-intervals, so that the marine fuel cell output is stable in each sub-interval and the auxiliary power source bears the fluctuation of the ship's required power;

[0022] S22. Each sub-interval is further divided into a start-up interval, a departure interval, an arrival interval, a medium-high power interval, and a low power interval;

[0023] S23. Convert the curve of the change of the ship's power demand versus the running time in the starting interval to the open circuit-idle start condition to obtain the output power-time curve of the marine fuel cell in the starting interval;

[0024] S24. Convert the curve of the change of the ship's power demand versus the operating time in the departure interval to a fast load change condition between idle speed and rated output, and obtain the output power-time curve of the marine fuel cell in the departure interval;

[0025] S25. Convert the curve of the change of ship power demand with operation time in the port area into a rapid load change between idling and open circuit, and obtain the output power-time curve of the marine fuel cell in the port area;

[0026] S26. Based on the energy management strategy in the medium and high power range, the fuel cell and the auxiliary power source jointly provide power, and the auxiliary power source bears all fluctuations. The average power demand in a single medium and high power sub-range is calculated according to the curve of the change of the ship's power demand in the medium and high power range with the running time, and then the average power demand is multiplied by the power source power ratio coefficient to obtain the output power of the ship fuel cell in the sub-range, and then the output power-time curve of the ship fuel cell in the medium and high power range is obtained;

[0027] S27. Based on the energy management strategy in the low power interval, the fuel cell provides all power and charges the auxiliary power source at the same time, and the auxiliary power source bears all fluctuations. The average power demand of a single low power sub-interval is calculated according to the curve of the change of the ship's power demand in the low power interval with the running time, and the output power of the ship fuel cell in the sub-interval is obtained by multiplying the average power demand of the sub-interval by the output factor, thereby obtaining the output power-time curve of the ship fuel cell in the low power interval;

[0028] S28. Normalize the output power of all converted fuel cell output power-time curves to obtain the basic working conditions for the rapid life test.

[0029] Further, the energy management allocation principle of step S21 includes: the output power of the marine fuel cell in each sub-interval is single; each sub-interval includes arrival at the port, departure from the port, or the initial stage of the sub-interval is one of variable load; and,

[0030] The basic working condition of step S28 includes several voyages including departure and arrival, and each voyage is connected by downtime.

[0031] Further, step S3 includes the following sub-steps:

[0032] S31. Identify the variable load section and the stable output power section of each sub-interval in the basic working condition, execute step S32 for the variable load section, and then execute step S33 for the stable output power section;

[0033] S32. Determine the load change time of the load change section according to the response rate of the fuel cell test bench and the marine fuel cell as the load change time of the sub-interval under the acceleration condition;

[0034] S33. Shorten the marine fuel cell output power-time curve within all sub-intervals of the stable output power segment according to the set multiple of the fuel cell output power;

[0035] S34. Adjust the region where the local load change rate is unreasonable in each sub-interval to obtain the normalized marine fuel cell output power-time curve of the final acceleration condition.

[0036] Furthermore, step S32 adopts a proportional multiple acceleration scheme, including setting the load change time to 30 to 60 seconds according to the load change amplitude.

[0037] Further, step S4 includes the following sub-steps:

[0038] S41. Performing a rapid activation and stability test on the tested stack of the marine fuel cell to obtain the performance test results of the marine fuel cell after activation;

[0039] S42. Based on the performance test results of the marine fuel cell after activation, determine the current density reference point of the stack output attenuation, the operating conditions when the test is completed, and each actual current density point of the normalized marine fuel cell output power in the accelerated condition, as well as the operating conditions at each actual current density point.

[0040] Further, step S5 includes the following sub-steps:

[0041] S51. Install a marine fuel cell on a fuel cell test bench, set up an automatic operating cycle test program, and select a current density reference point as a reference point for monitoring the stack voltage decay rate;

[0042] S52. After the tested fuel cell stack of the marine fuel cell is activated and its performance is relatively stable, a rapid life test under accelerated conditions is performed;

[0043] S53. The test starts with a power generation performance, electrochemical impedance spectroscopy, and cyclic voltammetry test. After each test of several accelerated operating cycles, a power generation performance, electrochemical impedance spectroscopy, and cyclic voltammetry test are performed;

[0044] S54. After the operating conditions at the time of test completion are reached, the accelerated life of the marine fuel cell is obtained, and the rapid life test under accelerated conditions is ended.

[0045] Further, step S6 includes the following sub-steps:

[0046] S61. Determine the acceleration factor based on the basic marine operating conditions and accelerated operating conditions;

[0047] S62. Multiply the accelerated life of the marine fuel cell by the above acceleration factor to obtain the actual service life of the marine fuel cell.

[0048] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the invention, nor is it intended to limit the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0050] Figure 1 A schematic diagram of the steps of the life prediction method for a marine fuel cell in Example 1 is shown;

[0051] Figure 2 A schematic diagram of actual ship operating condition data of the real ship "Mei Hyatt" in Example 2 is shown;

[0052] Figure 3 A schematic diagram showing the conversion from the (actual ship) reference operating condition to the (marine fuel cell life test) basic operating condition in the first voyage of Example 2 is shown;

[0053] Figure 4 A schematic diagram showing the conversion from the (actual ship) reference operating condition to the basic operating condition of the marine fuel cell life test) in the second voyage of Example 2 is shown;

[0054] Figure 5 A schematic diagram showing the conversion from the basic operating condition to the acceleration operating condition of Embodiment 2 is shown;

[0055] Figure 6 A schematic flow chart of the life prediction method of a marine fuel cell according to Example 2 is shown. DETAILED DESCRIPTION

[0056] Embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0057] As used herein, the term "including" and its variations mean open inclusion, i.e., "including but not limited to". Unless otherwise stated, the term "or" means "and / or". The term "based on" means "based at least in part on". The terms "an example embodiment" and "an embodiment" mean "at least one example embodiment". The term "another embodiment" means "at least one additional embodiment". The terms "first", "second", etc. may refer to different or the same objects. Other explicit and implicit definitions may also be included below.

[0058] The following first introduces the professional terms and their definitions involved in the present invention.

[0059] Marine fuel cell: an engine system that converts chemical energy into electrical energy through electrochemical reactions of hydrogen and oxygen, specifically including fuel gas system, air system, coolant system, fuel cell stack, etc.

[0060] Example 1

[0061] One embodiment of the present invention discloses a life prediction method for a marine fuel cell, such as Figure 1 As shown, the following steps are included:

[0062] S1. Acquire actual ship operating condition data and obtain reference operating conditions of ship power requirements after processing;

[0063] Specifically, the above-mentioned reference operating conditions include several combinations or all of the characteristic operating conditions such as arrival at the port, departure from the port, acceleration, deceleration, load change, high-speed navigation and low-speed navigation;

[0064] S2. Divide the reference operating condition into several sub-intervals, and convert the ship demand power in each sub-interval into the output power of the marine fuel cell according to the energy management strategy to obtain the marine basic operating condition;

[0065] Specifically, the basic principle of dividing the reference working condition into several sub-intervals is to unify the fuel cell output power, which is convenient for data processing, and then obtain the marine fuel cell output power (single value) of each sub-interval, and the marine fuel cell output power of each sub-interval is combined as the marine basic working condition;

[0066] S3. Convert the marine basic working condition into the accelerated working condition for rapid life test;

[0067] Specifically, the marine basic working condition is accelerated to obtain the output power of the marine fuel cell under the accelerated working condition;

[0068] S4. Conduct rapid activation and stability tests on the tested fuel cell stack of the marine fuel cell, determine the current density reference point for monitoring the fuel cell stack performance degradation, and the operating conditions when the test is completed;

[0069] Specifically, after determining the monitoring point, the use time of the marine fuel cell when the stack performance decay reaches a set level can be obtained as the fuel cell life;

[0070] S5. Perform a rapid life test on the marine fuel cell according to the above-mentioned accelerated operating conditions and current density reference point and the operating conditions when the test is completed to obtain the accelerated life of the marine fuel cell;

[0071] Specifically, the rapid life test, i.e., the accelerated test, can obtain the accelerated life (measured value) of the marine fuel cell;

[0072] S6. Determine the acceleration factor according to the basic marine operating conditions and the accelerated operating conditions, and obtain the actual service life of the marine fuel cell in combination with the above-mentioned accelerated life.

[0073] Specifically, the actual service life (predicted value) of a marine fuel cell is equal to the acceleration factor multiplied by the accelerated life.

[0074] Compared with the existing technology, this embodiment provides a method for quickly evaluating the life of marine fuel cells based on actual ship operating conditions, which includes the formulation of working conditions for rapid life tests and life test evaluation. It is suitable for scientific prediction of the service life of fuel cells when hydrogen fuel cells are used as the power source in hybrid ship propulsion, saving experimental costs and R&D cycles. This method fills the gap in the current lack of relevant life assessment methods in the industry, and provides support and effective basis for the development of fuel cells in the field of ship applications.

[0075] Example 2

[0076] Based on the improvement of Example 1, step S1 further includes the following sub-steps:

[0077] S11. Obtaining actual ship operating data (i.e. actual ship operation data);

[0078] S12. According to the actual ship operating condition data, the curve of the change of ship power demand with operation time is determined as the input of the life prediction method of the ship fuel cell, which comes from the Hyatt, such as Figure 2 As shown;

[0079] S13. Data processing is performed on the curve of the change of the ship's power demand over the running time, wherein the data processing includes identifying characteristic operating conditions and segmenting according to characteristic operating conditions; the characteristic operating conditions include arrival at the port, departure from the port, acceleration, deceleration, load change, high-speed navigation and low-speed navigation, etc.;

[0080] S14. From the data processing results, select the change curve segments containing characteristic operating conditions whose number exceeds the first set value and whose types exceed the second set value to form a reference operating condition, and the remaining data can be removed.

[0081] Preferably, the characteristic operating conditions covered by the reference operating conditions include arrival at port, departure from port, acceleration, deceleration, load change, high-speed navigation and low-speed navigation.

[0082] Preferably, step S2 further includes the following sub-steps:

[0083] S21. According to the energy management allocation principle, the reference operating condition is divided into several sub-intervals, so that the marine fuel cell output is stable in each sub-interval and the auxiliary power source bears the fluctuation of the ship's required power;

[0084] The above energy management allocation principle includes: the output power of the marine fuel cell in each sub-interval is single (singularized); and the initial stage of each sub-interval is variable load (except for arrival and departure). Through this energy management allocation strategy, the fuel cell in the sub-interval has a stable output, and the auxiliary power source, generally a lithium battery or supercapacitor, bears the power fluctuation;

[0085] S22. Each sub-interval is further divided into a start-up interval, a departure interval, an arrival interval, a medium-high power interval (greater than 40% of the maximum power), and a low power interval (less than or equal to 40% of the maximum power);

[0086] S23. Convert the curve of the change of the ship's power demand versus the running time in the starting interval to the open circuit-idle start condition to obtain the output power-time curve of the marine fuel cell in the starting interval;

[0087] S24. Convert the curve of the change of the ship's power demand versus the running time in the departure interval to a fast load change condition between idling and rated output, and obtain the output power-time curve of the marine fuel cell in the departure interval;

[0088] S25. Convert the curve of the change of ship power demand with operation time in the port area into a rapid load change between idling and open circuit, and obtain the output power-time curve of the marine fuel cell in the port area;

[0089] S26. Based on the energy management strategy in the medium and high power range, the fuel cell and the auxiliary power source jointly provide power, and the auxiliary power source bears all fluctuations. The average power demand in a single medium and high power sub-range is calculated according to the curve of the change of the ship's power demand in the medium and high power range with the running time, and then the average power demand is multiplied by the power source power ratio coefficient (for example, 60% to 90%) to obtain the output power of the ship fuel cell in the sub-range, and then the output power-time curve of the ship fuel cell in the medium and high power range is obtained;

[0090] S27. Based on the energy management strategy in the low power interval, the fuel cell provides all power and charges the auxiliary power source at the same time, and all fluctuations are borne by the auxiliary power source. The average power demand of a single low power sub-interval is calculated according to the curve of the change of the ship's power demand in the low power interval with the running time, and the average power demand of the sub-interval is multiplied by the output factor (such as 1.1, 1.3, etc.) to obtain the output power of the ship fuel cell in the sub-interval, and then the output power-time curve of the ship fuel cell in the low power interval is obtained;

[0091] S28. Normalize the output power of all converted fuel cell output power-time curves to obtain the basic working conditions for the rapid life test.

[0092] Figure 3 Schematic diagram of the conversion from (actual ship) reference conditions to (marine fuel cell life test) basic conditions in the first voyage. Figure 3 (a) in the figure represents the actual marine reference operating data. Figure 3 (b) in the figure represents the basic condition. Figure 4 Schematic diagram of the conversion from (actual ship) reference conditions to (marine fuel cell life test) basic conditions in the second voyage. Figure 4 (a) in the figure represents the actual marine reference operating data. Figure 4 (b) in the figure represents the basic condition.

[0093] Preferably, the basic operating conditions of step S28 (including the operating conditions corresponding to each sub-interval) include several voyages including departure and arrival, and each voyage is connected by downtime. It is simulated that there will be downtime after a voyage ends.

[0094] Except for the sub-intervals of arrival and departure, the initial stage of the above sub-intervals is the load change stage, and the load change slope is determined according to the speed of load change in the actual ship working conditions.

[0095] Preferably, step S3 (converting the basic operating condition to the acceleration operating condition) further includes the following sub-steps:

[0096] S31. Identify the variable load section and the stable output power section of each sub-interval in the basic working condition, execute step S32 for the variable load section, and then execute step S33 for the stable output power section;

[0097] S32. Determine the load change time of the load change section according to the response rate of the fuel cell test bench and the marine fuel cell, as the load change time of the sub-interval under the acceleration condition; generally, an equal-proportional acceleration scheme can be adopted, and the load change time is set to 30 to 60s according to the magnitude of the load change. An unequal-proportional acceleration scheme can also be adopted, and the conversion method is similar, only some stable power sections are shortened at a higher rate to achieve a faster speed change effect;

[0098] S33. Shorten the marine fuel cell output power-time curve within all sub-intervals of the stable output power segment according to the set multiple of the fuel cell output power;

[0099] S34. According to the actual situation, the region where the local load change rate is unreasonable in each sub-interval is adjusted to obtain the normalized marine fuel cell output power-time curve of the final acceleration condition.

[0100] Figure 5 The schematic diagram of the conversion from basic working condition to acceleration working condition is as follows: Figure 5 (a) in the figure is the basic working condition for the combined ship. Figure 5 (b) in the figure is the accelerated condition for marine fuel cell life test.

[0101] The above steps S1 to S3 are the accelerated working condition formulation method in the life prediction method of the marine fuel cell, and the following steps S4 to S6 are the rapid life test evaluation method.

[0102] Preferably, step S4 further includes the following sub-steps:

[0103] S41. Performing a rapid activation and stability test on the tested stack of the marine fuel cell to obtain the performance test results of the marine fuel cell after activation;

[0104] S42. After selecting the accelerated operating condition spectrum, determine the current density reference point of the stack output attenuation, the operating conditions when the test is completed, and each actual current density point of the normalized marine fuel cell output power in the accelerated condition, as well as the operating conditions at each actual current density point, based on the performance test results of the marine fuel cell after activation.

[0105] Preferably, step S5 further includes the following sub-steps:

[0106] S51. Install a marine fuel cell on a fuel cell test bench, set up an automatic operating cycle test program, and select a current density reference point as a reference point for monitoring the stack voltage decay rate;

[0107] S52. After the tested fuel cell stack of the control ship fuel cell is activated and its performance is relatively stable (under the same current density, the voltage fluctuation does not exceed 5%), a rapid life test under accelerated conditions (accelerated cycle condition test) is performed;

[0108] S53. The test starts with a power generation performance (IV curve), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and other tests. After each test of several accelerated operating cycles, a power generation performance (IV curve), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and other tests are performed;

[0109] S54. Specify the operating conditions when the test is completed (test end conditions, also fuel cell life end conditions): According to the duration of a cycle of the accelerated working condition and in combination with the actual situation, specify the test end conditions as the total number of cycles, for example, the test ends after 1000 cycles; or, continue testing until the voltage at the reference current density point decays to a set value (for example, decays to 5% or 10% of the initial value). After reaching the operating conditions when the test is completed, the accelerated life of the marine fuel cell is obtained, and the rapid life test of the accelerated working condition ends.

[0110] Preferably, the operating condition when the test is completed is when the voltage output of the tested battery stack decays to 20% of the initial voltage at the reference current density, or when the voltage of a single cell is lower than 0.4 V. During the cycle test, the changes in various operating conditions are monitored and recorded, and the changes in performance parameters such as the single cell voltage and the battery stack voltage are recorded.

[0111] Preferably, step S6 further includes the following sub-steps:

[0112] S61. Determine the acceleration factor based on the basic marine operating conditions and accelerated operating conditions;

[0113] Specifically, prepare two identical battery stacks or two identical monolithic cells. Under basic conditions, test the durability of one of the battery stacks or monolithic cells for a certain period of time (e.g., 500-3000 hours), test and record the IV curve, CV or EIS at certain intervals. For another identical battery stack or monolithic cell under accelerated conditions, test it for a certain period of time (e.g., 200-500 hours) according to the aforementioned method, and perform cyclic testing and record IV, CV or EIS.

[0114] The first method for determining the acceleration factor η is to calculate the electrochemically active area (ECSA) of the catalyst layer based on the CV or EIS obtained under the basic working condition and the accelerated working condition. The calculation method can be found in the relevant literature. Those skilled in the art can understand that the decay of ECSA over time is plotted into a curve. Select three points where the ECSA decays by a certain proportion (such as decay of 20%, 30%, and 40%). The corresponding test durations under the basic working condition are T1, T2, and T3, and the corresponding test durations under the accelerated working condition are t1, t2, and t3. The calculation formula of the acceleration factor is:

[0115]

[0116] The second method to determine the acceleration factor η is to calculate the voltage decay rate at the reference current density point based on the IV curves obtained under the basic working condition and the accelerated working condition, and the ratio of the two voltage decay rates is the acceleration factor. Generally, the voltage decay rates corresponding to low current density, medium current density and high current density are different, so the reference current density selected corresponds to the higher power working point commonly used in the actual ship operation process.

[0117] S62. Multiply the accelerated life of the marine fuel cell by the above acceleration factor to obtain the actual service life of the marine fuel cell.

[0118] In addition, the fuel cell voltage decay data obtained from the test under accelerated conditions within a certain period of time can be used to estimate the future voltage decay using a data-driven algorithm model to obtain the end-of-life time. Preferably, the algorithm model in Chinese patents CN117558947A and CN117525500A is used to estimate the life under accelerated conditions.

[0119] When implemented, the rapid life test method process is as follows Figure 6 The actual operating conditions of large cruise ships in a certain river basin are used as input to develop a rapid life test acceleration condition, and this accelerated condition is used to evaluate the life of marine fuel cells. The specific implementation process is as follows:

[0120] 1. After data capture and data smoothing, the actual ship operation demand power-time curve is obtained from the reference Hybrid Ship ECMS Control Strategy ([J / OL]. Journal of Wuhan University of Technology (Transportation Science and Engineering Edition), April 2024), such as Figure 2 As shown;

[0121] 2. After data interception and combination, two sections of actual ship operation reference conditions were obtained. The selection principle was to retain the complete actual ship characteristic conditions and ensure that each section of the reference condition could be tested and completed within 1 day. The operation time of each reference condition was 8-10 hours, representing a complete voyage between departure and arrival.

[0122] 3. Divide each reference condition into several sub-intervals, such as Figure 3 As shown, the first reference operating condition sub-interval 2 to 11 and the second reference operating condition sub-interval 14 to 21 are both normal navigation intervals, sub-intervals 1 and 13 are start-up-departure intervals, and sub-intervals 12 and 22 are arrival intervals. The average required power of sub-intervals 2 to 11 and 14 to 21 is calculated using the following formula:

[0123]

[0124] Where P is the required power in the interval, t is the time in the interval, and Pn is the average required power in the interval.

[0125] 4. Convert the reference working condition to the basic working condition for life test: sub-intervals 1 and 12 are replaced by 1 starting working condition plus 1 idle-rated variable load; sub-intervals 12 and 22 are replaced by 1 idle-stop variable load; when the average required power Pn is greater than 900kW in the sub-interval, the basic working condition corresponds to the interval power Pn'=Pn×85%; when the average required power Pn is less than 900kW, the basic working condition corresponds to the interval power Pn'=Pn×1.3. That is, in the medium and high power range, the marine fuel cell and the auxiliary battery jointly provide power, and in the low power range, the marine fuel cell provides power while charging the auxiliary battery.

[0126] 5. Combine the two basic working conditions into the marine basic working condition, and add a 1-hour downtime to the two working conditions to facilitate the conversion of the basic working condition into the acceleration working condition. When testing according to the basic working condition, due to the different conditions of the actual test bench, when the 24-hour continuous test is not met, the downtime can be extended to 8 to 16 hours; in addition, if it is necessary to simulate the actual working condition of the ship arriving at the port without stopping, the connection working condition can be changed from the shutdown condition to the idle condition. After the working conditions are combined, the power is normalized to obtain a universal marine basic working condition.

[0127] 6. Convert the basic working condition to the accelerated working condition: Preferably, shorten the basic working condition time by 10 times, that is, each working condition point t n is the time corresponding to the nth working point of the basic working condition, and t'n is the time corresponding to the nth working point after conversion. After the time is shortened by the multiplier, some working points need to be adjusted to make the lifting and lowering rate ≥30s and the duration of each platform ≥60s to meet the actual conditions of the test bench. After conversion and adjustment, the following is obtained Figure 5 The acceleration condition shown.

[0128] 7. Rapidly activate the fuel cell stack under test, and then perform a 2-5h stability test after activation. When the stack voltage fluctuates by no more than 5% at the rated operating point, the stack can be considered to have entered the stable stage. Test the IV, EIS and CV of the stack in the initial stable stage.

[0129] 8. The reference current density point is selected as the current density corresponding to the rated stack voltage at the beginning of the test. In this embodiment, the reference current density point is 1.6A / cm 2 In other embodiments, the preferred reference current density point is 1.2-1.8 A / cm 2 .

[0130] 9. According to the peak power or peak current designed for the battery stack, convert the normalized power in the acceleration condition into the corresponding current density, input the current density-time curve and the corresponding operating conditions into the control device of the test bench, and program the test process.

[0131] 10. Execution of accelerated working condition test: Execute the cyclic working condition test according to the program of the test bench. In this embodiment, the cycle of the accelerated working condition is about 2 hours. Every 20 cycles, IV, EIS and CV tests are performed until the test is completed. In this embodiment, the rapid life test is terminated after 1000 cycles (2000 hours); in other embodiments, preferably, the test is terminated after 250 to 1500 cycles, or the voltage decay at the reference current density point reaches 5%.

[0132] 11. Prepare 2 standard areas (25cm 2 ) Monolithic battery, all conditions of the membrane electrode are consistent with those of the tested battery stack. Monolithic battery 1 is tested for 200 hours according to the above-mentioned accelerated working condition test method, and the ECSA is calculated based on the integral area of ​​the CV curve to obtain the ECSA attenuation ratio. Monolithic battery 2 is tested according to the basic working condition. In this embodiment, the first and second basic working conditions are connected by a 12-hour shutdown condition, which is determined by the sustainable working time of the tester per day. The complete basic working condition single cycle period is about 18 hours, and a total of 30 hours of testing is required. IV, EIS and CV are recorded once every 5 cycles, and the ECSA attenuation ratio under the basic working condition is also calculated by the integral area of ​​the CV curve. The acceleration factor is calculated by selecting the duration corresponding to the three basic working conditions and accelerated working conditions with ECSA attenuation ratios of 10%, 20% and 30%. The calculation method adopts the first method for determining the acceleration factor mentioned above.

[0133] 12. The long-short time neural network algorithm model in Chinese patent CN117525500A is used to predict the life under accelerated conditions, and the duration when the voltage decays by 20% at the reference current density point is obtained, that is, the accelerated life. The accelerated life is multiplied by the acceleration factor to obtain the predicted life under the actual marine conditions of the tested battery stack.

[0134] Compared with the prior art, the life prediction method of a marine fuel cell provided in this embodiment has the following beneficial effects:

[0135] 1. It can accurately evaluate the service life of marine fuel cell engines, greatly saving experimental costs and R&D cycles.

[0136] 2. It shortens the experimental cycle, fills the gap in the accelerated life test of marine fuel cells, and provides support and effective basis for the development of fuel cells in the field of marine applications.

[0137] Embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terms used herein are selected to best explain the principles of the embodiments, practical applications, or improvements over the prior art, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A life prediction method for a marine fuel cell, characterized in that: The steps include: S1. Acquire actual ship operating condition data and obtain reference operating conditions of ship power requirements after processing; S2. Divide the reference operating condition into several sub-intervals, and convert the ship demand power in each sub-interval into the output power of the marine fuel cell according to the energy management strategy to obtain the marine basic operating condition; S3. Convert the marine basic working condition into the accelerated working condition for rapid life test; S4. Conduct rapid activation and stability tests on the tested fuel cell stack of the marine fuel cell, determine the current density reference point for monitoring the fuel cell stack performance degradation, and the operating conditions when the test is completed; S5. Perform a rapid life test on the marine fuel cell according to the above-mentioned accelerated operating conditions and current density reference point and the operating conditions when the test is completed to obtain the accelerated life of the marine fuel cell; S6. Determine the acceleration factor according to the basic marine operating conditions and the accelerated operating conditions, and obtain the actual service life of the marine fuel cell in combination with the above-mentioned accelerated life.

2. The life prediction method of a marine fuel cell according to claim 1, characterized in that: Step S1 further includes the following sub-steps: S11. Obtaining actual marine operating data; S12. Determine the curve of the change of ship power demand with operation time according to the actual ship operating condition data; S13. Data processing of the curve of the change of the ship's power demand with the running time, including characteristic operating condition identification and segmentation according to the characteristic operating condition; The characteristic operating conditions include arrival at a port, departure from a port, acceleration, deceleration, load change, high-speed navigation and low-speed navigation; S14. From the data processing results, select the change curve segments whose number of characteristic working conditions exceeds the first set value and whose types exceed the second set value to form a reference working condition.

3. The life prediction method of a marine fuel cell according to claim 2, characterized in that: The characteristic operating conditions covered by the reference operating conditions include arrival at the port, departure from the port, acceleration, deceleration, load change, high-speed navigation and low-speed navigation.

4. The life prediction method of a marine fuel cell according to claim 3, characterized in that: Step S2 further includes the following sub-steps: S21. According to the energy management allocation principle, the reference operating condition is divided into several sub-intervals, so that the marine fuel cell output is stable in each sub-interval and the auxiliary power source bears the fluctuation of the ship's required power; S22. Each sub-interval is further divided into a start-up interval, a departure interval, an arrival interval, a medium-high power interval, and a low power interval; S23. Convert the curve of the change of the ship's power demand versus the running time in the starting interval to the open circuit-idle start condition to obtain the output power-time curve of the marine fuel cell in the starting interval; S24. Convert the curve of the change of the ship's power demand versus the running time in the departure interval to a fast load change condition between idling and rated output, and obtain the output power-time curve of the marine fuel cell in the departure interval; S25. Convert the curve of the change of ship power demand with operation time in the port area into a rapid load change between idling and open circuit, and obtain the output power-time curve of the marine fuel cell in the port area; S26. Based on the energy management strategy in the medium and high power range, the fuel cell and the auxiliary power source jointly provide power, and the auxiliary power source bears all fluctuations. The average power demand in a single medium and high power sub-range is calculated according to the curve of the change of the ship's power demand in the medium and high power range with the running time, and then the average power demand is multiplied by the power source power ratio coefficient to obtain the output power of the ship fuel cell in the sub-range, and then the output power-time curve of the ship fuel cell in the medium and high power range is obtained; S27. Based on the energy management strategy in the low power interval, the fuel cell provides all power and charges the auxiliary power source at the same time, and the auxiliary power source bears all fluctuations. The average power demand of a single low power sub-interval is calculated according to the curve of the change of the ship's power demand in the low power interval with the running time, and the output power of the ship fuel cell in the sub-interval is obtained by multiplying the average power demand of the sub-interval by the output factor, thereby obtaining the output power-time curve of the ship fuel cell in the low power interval; S28. Normalize the output power of all converted fuel cell output power-time curves to obtain the basic working conditions for the rapid life test.

5. The life prediction method of a marine fuel cell according to claim 4, characterized in that: The energy management allocation principle of step S21 includes: the output power of the marine fuel cell in each sub-interval is single; each sub-interval includes arrival at the port, departure from the port, or the initial stage of the sub-interval is one of variable load; and, The basic working condition of step S28 includes several voyages including departure and arrival, and each voyage is connected by downtime.

6. The life prediction method of a marine fuel cell according to claim 5, characterized in that: Step S3 further includes the following sub-steps: S31. Identify the variable load section and the stable output power section of each sub-interval in the basic working condition, execute step S32 for the variable load section, and then execute step S33 for the stable output power section; S32. Determine the load change time of the load change section according to the response rate of the fuel cell test bench and the marine fuel cell as the load change time of the sub-interval under the acceleration condition; S33. Shorten the marine fuel cell output power-time curve within all sub-intervals of the stable output power segment according to the set multiple of the fuel cell output power; S34. Adjust the region where the local load change rate is unreasonable in each sub-interval to obtain the normalized marine fuel cell output power-time curve of the final acceleration condition.

7. The life prediction method of a marine fuel cell according to claim 6, characterized in that: Step S32 adopts a proportional multiple acceleration scheme, including setting the load change time to 30 to 60 seconds according to the load change amplitude.

8. The life prediction method of a marine fuel cell according to claim 7, characterized in that: Step S4 further includes the following sub-steps: S41. Performing a rapid activation and stability test on the tested stack of the marine fuel cell to obtain the performance test results of the marine fuel cell after activation; S42. Based on the performance test results of the marine fuel cell after activation, determine the current density reference point of the stack output attenuation, the operating conditions when the test is completed, and each actual current density point of the normalized marine fuel cell output power in the accelerated condition, as well as the operating conditions at each actual current density point.

9. The life prediction method of a marine fuel cell according to claim 8, characterized in that: Step S5 further includes the following sub-steps: S51. Install a marine fuel cell on a fuel cell test bench, set up an automatic operating cycle test program, and select a current density reference point as a reference point for monitoring the stack voltage decay rate; S52. After the tested fuel cell stack of the marine fuel cell is activated and its performance is relatively stable, a rapid life test under accelerated conditions is performed; S53. The test starts with a power generation performance, electrochemical impedance spectroscopy, and cyclic voltammetry test. After each test of several accelerated operating cycles, a power generation performance, electrochemical impedance spectroscopy, and cyclic voltammetry test are performed; S54. After the operating conditions at the time of test completion are reached, the accelerated life of the marine fuel cell is obtained, and the rapid life test under accelerated conditions is ended.

10. The life prediction method of a marine fuel cell according to any one of claims 1 to 9, characterized in that: Step S6 further includes the following sub-steps: S61. Determine the acceleration factor based on the basic marine operating conditions and accelerated operating conditions; S62. Multiply the accelerated life of the marine fuel cell by the above acceleration factor to obtain the actual service life of the marine fuel cell.

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