A fuel cell accelerated start-stop durability test method and device

Abstract

The present invention provides a fuel cell accelerated start-stop endurance test method and device, which allows the air supply pipeline to pass air to the cathode through a control device, and periodically passes air to the anode. If the maximum voltage of the single-chip battery is greater than the target voltage, air continues to be passed to the cathode of the stack. The present invention can quickly enable the stack to reach the operating condition where the start-stop test can be started without damaging the battery life, so that the impact of the start-stop operating condition on the battery life can be evaluated separately.

Description

Technical Field

[0001] The invention relates to the field of fuel cells, and in particular to a fuel cell accelerated start-stop endurance test method and device. Background Art

[0002] Vehicle fuel cells frequently experience various operating conditions, such as start-stop, variable load, idling, and high load. Among all dynamic conditions, start-up and shutdown conditions are a great test for the durability of the proton exchange membrane fuel cell system. Because during start-up and shutdown conditions, the vehicle fuel cell will generate high potential, causing oxidation corrosion of the catalyst carrier carbon material, thus reducing the life of the fuel cell system.

[0003] In order to explore the impact of start-stop conditions on battery life, a start-stop test is required. The start-stop test simulates the impact of starting a vehicle after a long shutdown on the life of the fuel cell. It requires starting when both the cathode and anode of the battery are filled with air. To achieve this state, the running fuel cell system needs to be shut down for dozens of hours, which results in a long test cycle and high cost.

[0004] At present, the durability test of automotive fuel cell stacks under comprehensive working conditions used in the fuel cell industry is not convenient for distinguishing the degree of influence of various working conditions on fuel cell components. The few test equipment used for simple start-stop endurance tests are also relatively complex, or have multiple airflow channels, or have too many controllers and sensors added, which are not easy to operate. The test results are easily affected by fault factors, or the test methods are significantly different from the actual automotive fuel cell working conditions, and too many variables that are inconsistent with the actual working conditions are introduced, which cannot reasonably reflect the attenuation rate of automotive fuel cells under start-stop conditions. Summary of the invention

[0005] The purpose of the present invention is to provide a method and device for accelerating the start-stop endurance test, in which air is used to purge the anode and cathode respectively without introducing an inert gas, so that the battery stack can quickly reach the operating condition where the start-stop test can be started without damaging the battery life (i.e., without generating a high potential), so that the impact of the start-stop condition on the battery life can be simply evaluated.

[0006] The present invention provides a fuel cell accelerated start-stop durability test method, comprising the following steps:

[0007] Air is periodically introduced into the anode of the stack;

[0008] Air is introduced into the cathode of the battery stack, and the maximum voltage of the single cell is detected after the air is introduced;

[0009] If the maximum voltage of the single cell is higher than the target voltage, continue to introduce air into the cathode of the battery stack.

[0010] Optionally, before air is introduced into the anode and cathode of the stack, the method further comprises:

[0011] Reduce the fuel cell system to idle power and then shut it down.

[0012] Optionally, the step of reducing the fuel cell system to idle power and then shutting it down comprises:

[0013] For a fuel cell system in a shutdown state, it is first started to change the load of the fuel cell stack to a first operating power at a set load change rate;

[0014] After running continuously for the first running time, the load is changed to the idle power at the set load change rate;

[0015] Shutdown.

[0016] Optionally, the step of reducing the fuel cell system to idle power and then shutting it down comprises:

[0017] For a fuel cell system in a non-shutdown state, the stack is loaded to idle power at a set load change rate;

[0018] Shutdown.

[0019] Optionally, the set load change rate is 1Kw / s-5Kw / s, the first operating power is 60%-70% of the rated power of the fuel cell stack, and the first operating time is 180s-500s.

[0020] Optionally, the step of periodically introducing air into the anode of the stack includes:

[0021] Periodically opening and closing a hydrogen exhaust valve connected to the anode of the stack;

[0022] Stop the operation after reaching the set number of times.

[0023] Optionally, the opening time of the hydrogen exhaust valve is 0.3s-3s, the opening interval time is 10s-200s, and the opening times are 8-20 times.

[0024] Optionally, the step of introducing air into the cathode of the battery stack and detecting the maximum voltage of the single-chip battery after introducing air comprises:

[0025] Open the stack entry stop valve and stack exit stop valve connected to the cathode of the stack to allow air to flow into the cathode of the stack;

[0026] Detect the maximum voltage of a single battery;

[0027] If the maximum voltage of a single battery is higher than the target voltage, air will continue to be supplied to the cathode of the battery stack through the air compressor after the maximum voltage of the single battery drops to the target voltage, and the maximum voltage of the single battery will continue to be detected after the air is supplied until the measured maximum voltage of the single battery is lower than the target voltage.

[0028] Optionally, when air is introduced into the cathode of the fuel cell stack through the inlet stop valve and the outlet stop valve, the maximum voltage of the single cell after the air is introduced is controlled to not exceed the monitoring voltage by controlling the opening of the inlet stop valve and the outlet stop valve; when air is introduced into the cathode of the fuel cell stack through the air compressor, the maximum voltage of the single cell after the air is introduced is controlled to not exceed the monitoring voltage by controlling the speed and operating time of the air compressor.

[0029] Optionally, the target voltage is 0mV-150mV, the monitoring voltage is 150mV-350mV, the openings of the inlet and outlet stop valves are 1%-5%, the speed of the air compressor is the minimum speed of the air compressor, and the operating time of the air compressor is 1-5s.

[0030] Optionally, before air is introduced into the anode and cathode of the fuel cell stack, the method further includes: cooling the fuel cell system so that the outlet temperature of the coolant is the same as the room temperature.

[0031] The present invention also provides a fuel cell accelerated start-stop endurance test device, comprising a fuel cell stack, a hydrogen pipeline, a gas supply pipeline, a hydrogen exhaust valve and a stack exit shut-off valve, the fuel cell stack comprising a cathode and an anode, the hydrogen pipeline and the hydrogen exhaust valve are connected to the anode of the fuel cell stack, the gas supply pipeline and the stack exit shut-off valve are connected to the cathode of the fuel cell stack, the gas supply pipeline is provided with a stack entry shut-off valve and an air compressor, the fuel cell accelerated start-stop endurance test device introduces air into the anode of the fuel cell stack through the hydrogen exhaust valve, and introduces air into the cathode of the fuel cell stack through the stack entry shut-off valve and the air compressor.

[0032] In summary, the beneficial effects brought by the present invention are:

[0033] 1. The present invention can quickly fill the cathode and anode of the stack with air by controlling the air compressor and various valves, while avoiding the generation of high potential in the process, avoiding unnecessary damage to the stack, and more realistically simulating the situation of starting the stack after the vehicle has been parked for a long time. This method does not require the stack to wait for several hours or even more than ten hours to fill the cathode and anode of the stack with air, greatly shortening the start-stop durability test time and reducing the test cost.

[0034] 2. Save time to create conditions that meet the start-stop test without introducing excess gas and excess gas channels.

[0035] 3. After the system is shut down, the stack water pump is controlled to operate to quickly reduce the stack temperature, thereby achieving a cold start state, which can more realistically simulate the situation of starting the stack after the vehicle has been parked for a long time.

[0036] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the following specifically cites a preferred embodiment and describes it in detail with the accompanying drawings as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A flow chart of the method for the accelerated start-stop endurance test provided by the present invention.

[0038] Figure 2 Schematic diagram of a device applicable to the present invention.

[0039] Description of Reference Numerals

[0040] 1-fuel cell stack, 2-inlet shut-off valve, 3-exit shut-off valve, 4-hydrogen discharge valve, 5-hydrogen pipeline, 6-cooling system, 61-fuel cell stack water pump, 62-cooling fan, 7-air supply pipeline, 71-air flow meter, 72-humidifier, 73-intercooler, 74-air compressor, 75-air filter. DETAILED DESCRIPTION

[0041] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0042] The terms "first", "second" and the like in the description and claims of the present invention are used to distinguish similar objects but not necessarily to describe a particular sequence or order.

[0043] The present embodiment provides a fuel cell accelerated start-stop endurance test device, comprising a fuel cell stack 1, an inlet shut-off valve 2, an outlet shut-off valve 3, a hydrogen exhaust valve 4, a hydrogen pipeline 5, a cooling system 6 and a gas supply pipeline 7.

[0044] The stack 1 includes a cathode (not shown in the figure) and an anode (not shown in the figure). When the fuel cell system is shut down, unreacted hydrogen will remain in the anode. The stack entry shutoff valve 2 is connected to the cathode gas inlet, and the stack exit shutoff valve 3 is connected to the cathode gas outlet. Air can enter the cathode from the stack entry shutoff valve 2 and leave the stack from the stack exit shutoff valve 3. By controlling the opening of the stack entry shutoff valve 2 and the stack exit shutoff valve 3, the amount of air entering and flowing out of the cathode can be controlled.

[0045] The hydrogen pipeline 5 is connected to the anode of the stack, and the hydrogen discharge valve 4 is connected to the anode. The hydrogen pipeline 5 is used to provide hydrogen to the anode; when the hydrogen discharge valve 4 is opened, air can enter the anode from the hydrogen discharge valve 4.

[0046] Specifically, the hydrogen pipeline 5 used in this embodiment is connected with a pressure reducing valve and a hydrogen source in sequence, and the high-pressure hydrogen provided by the hydrogen source is reduced in pressure by the pressure reducing valve and then enters the anode of the fuel cell stack 1 through the anode gas inlet. The hydrogen source in this embodiment is a hydrogen gas cylinder, and it can be understood that those skilled in the art can also flexibly select a suitable hydrogen source according to actual needs, such as a hydrogen generator, etc.

[0047] The cooling system 6 is configured to cool the stack 1, and includes a coolant and a drive device. In this embodiment, the coolant is deionized water, and the drive device includes a stack water pump 61. In addition, the cooling system 6 also includes a cooling fan 62. The cooling system 6 is set to simulate the stack temperature when the stack 1 is started after the vehicle has been parked for a long time, to ensure that it is a cold start, and to ensure the reliability of the experimental data.

[0048] The air supply line 7 is provided with an air flow meter 71, a humidifier 72, an intercooler 73, an air compressor 74 and an air filter 75 in order to provide the cathode with air that meets the actual vehicle operating conditions. Among them, the humidifier 72 is provided to humidify the proton exchange membrane to prevent the membrane electrode from being too dry, which reduces the ability of the proton exchange membrane to conduct protons or even damages it. It is worth mentioning that, due to cost and operational considerations, the device for humidifying the proton exchange membrane is omitted in some start-stop test devices, and the battery stack used does not have a self-humidification function. This simplifies the equipment and operation, but also increases the variables that the start-stop test does not match the actual vehicle operating conditions, affecting the reliability of the experimental data of the start-stop conditions.

[0049] According to the above configuration, this embodiment also provides a fuel cell accelerated start-stop durability test method, which is as follows:

[0050] Periodically introducing air into the anode of the stack 1;

[0051] Air is introduced into the cathode of the battery stack 1 to consume the residual hydrogen at the anode through the reaction of the battery stack 1, and the maximum voltage of the single cell is detected after the air is introduced;

[0052] If the maximum voltage of the single cell is higher than the target voltage, air continues to be introduced into the cathode of the battery stack 1.

[0053] The start-stop endurance test requires the fuel cell system to be shut down first. In this embodiment, the fuel cell system is already in a shutdown state. At this time, the fuel cell system needs to be started first, and the load change rate is set to change the load of the stack 1 to the first operating power. After running for the first operating time, the load is changed to the idle power at the set load change rate, and then shut down. Specifically, the load change rate is set to 1Kw / s-5Kw / s, the first operating power is 60%-70% of the rated power of the stack 1, and the first operating time is 180s-500s.

[0054] It should be noted that the start-stop endurance test is not conducted directly on the fuel cell system in the shutdown state in order to pre-wet the proton exchange membrane and reduce the test variables. Specifically, because this test requires ventilation of the anode and cathode of the fuel cell system, this ventilation is inconsistent with the actual vehicle operating conditions, which may cause the proton exchange membrane to be too dry, thereby increasing the test variables. Therefore, the fuel cell system needs to be operated for a period of time to produce water to wet the proton exchange membrane in order to better simulate the actual vehicle use scenario.

[0055] By extension, if the fuel cell system is not in a shutdown state, there is no need to operate the fuel cell system for a period of time first. The fuel cell system only needs to be loaded to idle power at a set load rate and then shut down.

[0056] Furthermore, when performing the above parameter settings, the load change rate is set to a lower value. This is to ensure that the fuel cell system will not experience a drastic load change from a higher power load state to a shutdown state, thereby reducing the impact of drastic load changes on the performance of the fuel cell stack 1. When the fuel cell system is started for a start-stop test next time, it can be considered that the degradation of the performance of the fuel cell stack 1 is only due to the influence of the single factor of starting and stopping the fuel cell stack, that is, the reliability of the experimental results is improved by reducing variables.

[0057] Preferably, in the above step, the cooling system 6 can be controlled to control the temperature of the coolant outlet of the stack 1 to 70-80°C during the execution of this step, which is the optimal operating temperature of the stack 1. It is worth mentioning that by controlling the coolant outlet temperature of the stack 1 and combining the above operating parameters, the stack 1 can reach a hydrothermal balance during operation, thereby ensuring the output performance of the battery.

[0058] As described above, when air is introduced into the cathode and air is periodically introduced into the anode to consume residual hydrogen, the maximum voltage of the single cell is controlled not to exceed the monitoring voltage by controlling the amount of air supplied.

[0059] Specifically, in this embodiment, the operation of periodically introducing air into the anode is to periodically open or close the hydrogen exhaust valve 4 to introduce air into the anode, the opening time of the hydrogen exhaust valve 4 is 0.3s-3s, the opening interval time is 10s-200s, and the opening times are 8-20 times.

[0060] Specifically, in this embodiment, the operation of introducing air into the cathode to consume the residual hydrogen is divided into the following steps:

[0061] (1) air is delivered to the cathode through the stack cut-off valve 2, and the maximum voltage of the single cell is controlled not to exceed the monitoring voltage by controlling the amount of air delivered, and the maximum voltage of the single cell is continuously monitored; when the maximum voltage of the single cell drops to the target voltage due to the consumption of hydrogen, the next step is carried out;

[0062] (2) air is delivered to the cathode through the air compressor 74, and the air intake is controlled so that the maximum voltage of the single cell does not exceed the monitoring voltage;

[0063] (3) Monitor the maximum voltage of the single-chip battery. If the maximum voltage of the single-chip battery exceeds or is equal to the target voltage, repeat the step of conveying air through the air compressor 74, and continue to monitor the maximum voltage of the single-chip battery after the air is introduced until the maximum voltage of the single-chip battery is less than the target voltage. If the maximum voltage of the single-chip battery directly measured after the air is introduced is less than the target voltage, it is confirmed that the hydrogen is completely consumed. In this step, the monitoring voltage value is set to facilitate the monitoring and control of the potential generated during the hydrogen consumption process to avoid high potentials that damage the battery life. The target voltage value is set to monitor whether the hydrogen has been completely consumed. Specifically, the target voltage is 0mV-150mV, and the monitoring voltage is 150mV-350mV.

[0064] Optionally, in the above scheme (3), if the maximum voltage of the single-chip battery exceeds or is equal to the target voltage, it is necessary to repeatedly deliver air through the air compressor 74. However, it is understandable that if the maximum voltage of the single-chip battery is equal to the target voltage at this time, it is also possible to choose not to deliver air to the cathode through the air compressor 74, but to directly shut down the air compressor 74. At this time, the maximum voltage of the single-chip battery will also drop to below the target voltage after a period of time. The principle of this operation is that although the air compressor 74 stops running, the air that was delivered to the cathode before the air compressor 74 stopped and before still stays at the cathode, can still be reacted, and will still be surplus after the reaction.

[0065] In this embodiment, when air is delivered to the cathode through the stack entry stop valve 2, the air intake of the cathode is controlled by controlling the opening of the stack entry stop valve 2 and the stack exit stop valve 3. Specifically, the opening of the stack entry stop valve 2 and the stack exit stop valve 3 are both 1%-5%. When air is introduced to the cathode of the stack 1 through the air compressor 74, the air intake of the cathode is controlled by controlling the speed and operation time of the air compressor 74. In this embodiment, the speed of the air compressor 74 is set to the minimum speed of the air compressor 74, and the operation time of the air compressor 74 is 1-5s.

[0066] In the present invention, the periodic opening and closing of the hydrogen exhaust valve 4, the control of the stop valve opening and the periodic opening and closing of the air compressor 74 are all for allowing air to enter the anode and cathode in small amounts and multiple times, so that hydrogen is reacted and consumed without generating high potential.

[0067] Optionally, the opening times of the hydrogen discharge valve 4 may not be set, and at least one of the control devices of the out-of-stack stop valve 3 and the air compressor 74 may be linked to the hydrogen discharge valve 4. When the control device of the out-of-stack stop valve 3 or the air compressor 74 is opened, the hydrogen discharge valve 4 is opened and closed periodically, and when the control device of the out-of-stack stop valve 3 or the air compressor 74 is closed, the hydrogen discharge valve 4 is closed. In this way, the step of operating the hydrogen discharge valve 4 separately can be omitted.

[0068] In addition, while the above steps are being performed, the cooling system 6 cools the fuel cell system so that the coolant outlet temperature is the same as the room temperature, so as to achieve the effect of cold start, which can better simulate the start of the fuel cell after long-term parking.

[0069] In summary, the present invention has at least the following beneficial effects:

[0070] 1. The present invention can quickly fill the cathode and anode of the stack 1 with air by controlling the air compressor 74 and various valves, and can avoid the generation of high potential in the process, avoid unnecessary damage to the stack 1, and can more realistically simulate the situation of starting the stack 1 after the vehicle has been parked for a long time. This method does not require the stack 1 to wait for several hours or even more than ten hours to fill the cathode and anode of the stack 1 with air, greatly shortening the start-stop durability test time and reducing the test cost.

[0071] 2. Save time to create conditions that meet the start-stop test without introducing excess gas and excess gas channels.

[0072] 3. After the system is shut down, the stack water pump 61 is controlled to operate, so that the temperature of the stack 1 is quickly reduced, thereby achieving a cold start state, which can more realistically simulate the situation of starting the stack 1 after the vehicle has been parked for a long time.

[0073] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A fuel cell accelerated start-stop durability test method, comprising the following steps: Before air is introduced into the anode and cathode of the fuel cell stack, the fuel cell system in the shutdown state is first started, and the fuel cell stack is loaded to the first operating power at a set load change rate. After the first operating time is continuously operated, the load is changed to the idle power at the set load change rate, and then the system is shut down; Air is periodically introduced into the anode of the stack; Air is introduced into the cathode of the battery stack, and the maximum voltage of the single cell is detected after the air is introduced; If the maximum voltage of the single cell is higher than the target voltage, continue to introduce air into the cathode of the battery stack.

2. The fuel cell accelerated start-stop durability test method according to claim 1, characterized in that: Before air is introduced into the anode and cathode of the stack, the method further includes: for a fuel cell system in a non-shutdown state, the stack is loaded to idle power at a set load change rate, and then shut down.

3. The fuel cell accelerated start-stop durability test method according to claim 1 or 2, characterized in that: The set load change rate is 1Kw / s-5Kw / s, the first operating power is 60%-70% of the rated power of the fuel cell stack, and the first operating time is 180s-500s.

4. The fuel cell accelerated start-stop durability test method according to claim 1, characterized in that: The steps of periodically introducing air into the anode of the stack include: Periodically opening and closing a hydrogen exhaust valve connected to the anode of the stack; Stop the operation after reaching the set number of times.

5. The fuel cell accelerated start-stop durability test method according to claim 4, characterized in that: The opening time of the hydrogen exhaust valve is 0.3s-3s, the opening interval is 10s-200s, and the opening times are 8-20 times.

6. The fuel cell accelerated start-stop durability test method according to claim 1, characterized in that: The steps of introducing air into the cathode of the battery stack and detecting the maximum voltage of the single cell after introducing air include: Open the stack entry stop valve and stack exit stop valve connected to the cathode of the stack to allow air to flow into the cathode of the stack; Detect the maximum voltage of a single battery; If the maximum voltage of a single battery is higher than the target voltage, air will continue to be supplied to the cathode of the battery stack through the air compressor after the maximum voltage of the single battery drops to the target voltage, and the maximum voltage of the single battery will continue to be detected after the air is supplied until the measured maximum voltage of the single battery is lower than the target voltage.

7. The fuel cell accelerated start-stop durability test method according to claim 6, characterized in that: When air is introduced into the cathode of the fuel cell stack through the inlet stop valve and the outlet stop valve, the maximum voltage of the single cell after the air is introduced is controlled to not exceed the monitoring voltage by controlling the opening of the inlet stop valve and the outlet stop valve; when air is introduced into the cathode of the fuel cell stack through the air compressor, the maximum voltage of the single cell after the air is introduced is controlled to not exceed the monitoring voltage by controlling the speed and operating time of the air compressor.

8. The fuel cell accelerated start-stop durability test method according to claim 7, characterized in that: The target voltage is 0mV-150mV, the monitoring voltage is 150mV-350mV, the openings of the inlet stop valve and the outlet stop valve are 1%-5%, the speed of the air compressor is the minimum speed of the air compressor, and the operation time of the air compressor is 1-5s.

9. The fuel cell accelerated start-stop durability test method according to claim 1, characterized in that: Before air is introduced into the anode and cathode of the fuel cell stack, the method further includes: cooling the fuel cell system so that the outlet temperature of the coolant is the same as the room temperature.

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