Fuel cell system hydrogen leakage detection method and device

Abstract

The invention provides a fuel cell system hydrogen leakage detection method and device, and the method comprises the steps: firstly, judging whether a fuel cell system starts to enter a hydrogen pressure maintaining state or not; then, after the hydrogen pressure maintaining state is maintained for a preset duration, the current actual pressure value in the hydrogen channel is measured, and the current theoretical pressure value in the hydrogen channel is calculated by adopting a preset formula; and finally, determining the hydrogen leakage risk degree of the fuel cell system according to the difference between the theoretical pressure value and the actual pressure value. By comparing the theoretical pressure value with the actual pressure value, the leakage condition of the hydrogen can be accurately and reliably judged, and meanwhile, an additional hydrogen concentration sensor does not need to be added, so that the cost, the mass and the volume of a fuel cell system can be effectively saved.

Description

Technical Field

[0001] The present invention belongs to the technical field of fuel cells, and in particular relates to a method and device for detecting hydrogen leakage in a fuel cell system. Background Art

[0002] A fuel cell is a device that uses hydrogen and oxygen to generate electricity in an electrochemical reaction. It has the advantages of low operating temperature, high power density, fast startup, and low environmental pollution. It is widely used in fields such as transportation.

[0003] The fuel cell consists of an anode, a cathode and an electrolyte membrane. When in operation, hydrogen is supplied to the anode and decomposed into protons (H + ) and electron (e - ), electrons flow to the cathode through an external circuit, generating an electric current. The electrolyte membrane is a layer of special material that only allows protons to pass through, forcing electrons to move through an external circuit. On the cathode side, oxygen absorbs electrons flowing from the anode and combines with protons that pass through the electrolyte membrane to generate emissions - water.

[0004] At present, the development of fuel cells has received great attention, and at the same time, higher requirements have been put forward for their safe operation. Hydrogen leakage in fuel cell systems will cause serious safety hazards, and there are many possible leakage points in the hydrogen pipeline of fuel cell systems. The leakage modes include internal leakage and external leakage, such as leakage of the stack manifold, leakage of various components, leakage of connecting pipelines, and internal leakage of components.

[0005] Since fuel cell systems are usually used in vehicles, leaked hydrogen will diffuse quickly during vehicle operation, making it impossible to accurately test. At the same time, even if hydrogen leaks occur during the normal operation of the fuel cell system, the hydrogen pressure regulation function will replenish the leaked hydrogen through a pressure closed loop, making the system insensitive to hydrogen leaks.

[0006] At present, the detection methods for hydrogen leakage in fuel cells mainly adopt the following two methods: 1. Using hydrogen concentration sensors for detection; 2. Monitoring the difference between the actual consumption rate of hydrogen and the theoretical consumption rate to judge hydrogen leakage. However, the first method requires a hydrogen concentration sensor for detection, but the hydrogen concentration sensor cannot detect smaller leaks, and the hydrogen concentration sensor has the risk of failure as the use time increases. In the actual detection process, there is a large difference between the actual hydrogen consumption and the calculated amount, resulting in the second method being unable to accurately judge smaller leaks.

[0007] Therefore, accurately detecting hydrogen leakage during fuel cell operation is an important issue that needs to be solved urgently. Summary of the invention

[0008] The embodiments of the present invention provide a method and device for detecting hydrogen leakage in a fuel cell system, so as to solve the problem that the existing methods cannot accurately detect hydrogen leakage in the fuel cell.

[0009] In order to solve the above technical problems, the embodiments of the present invention disclose the following technical solutions:

[0010] One aspect of the present invention provides a method for detecting hydrogen leakage in a fuel cell system, the method comprising:

[0011] S100, determining whether the fuel cell system has begun to enter a hydrogen pressure maintenance state,

[0012] If yes, execute S200; otherwise, execute S100 again;

[0013] S200, after the hydrogen pressure maintaining state reaches a preset time, measuring the current actual pressure value in the hydrogen channel;

[0014] S300, using a preset formula to calculate the current theoretical pressure value in the hydrogen channel;

[0015] S400: Determine the risk level of hydrogen leakage of the fuel cell system according to the difference between the theoretical pressure value and the actual pressure value.

[0016] Optionally, the step S100 includes:

[0017] S101, determining whether the fuel cell system is shut down,

[0018] If yes, execute S102; otherwise, execute S101 again;

[0019] S102, determining whether the pressure value in the hydrogen channel is within a preset pressure maintenance range,

[0020] If so, execute S200; otherwise, issue a warning message of pressure holding failure.

[0021] Optionally, the step S200 includes:

[0022] S201, starting from the fuel cell system entering the hydrogen pressure maintenance state, recording the time of maintaining the hydrogen pressure maintenance state;

[0023] S202: After the hydrogen pressure maintaining state is maintained for a preset time, the current actual pressure value in the hydrogen channel is measured using a pressure sensor.

[0024] Optionally, the step S300 includes:

[0025] S301, measuring the initial pressure value in the hydrogen channel when the fuel cell system begins to enter the hydrogen pressure maintenance state;

[0026] S302, calculating the initial hydrogen mass in the hydrogen channel when the fuel cell system begins to enter the hydrogen pressure maintaining state according to the initial pressure value;

[0027] S303, monitoring the temperature of the fuel cell stack in real time through a temperature sensor;

[0028] S304, calculating the current theoretical pressure value in the hydrogen channel according to the initial pressure value, the initial hydrogen mass and the stack temperature.

[0029] Optionally, the step S302 includes:

[0030] The initial hydrogen mass m0 is calculated using the following formula:

[0031]

[0032] Among them, P0 represents the initial pressure value in the hydrogen channel; μ represents the molar mass of hydrogen; V represents the volume of the hydrogen channel; a and b represent preset parameters, a is related to the intermolecular attraction, and b is related to the intermolecular repulsion; R represents the gas constant; T represents the temperature of the current fuel cell stack.

[0033] Optionally, the step S304 includes:

[0034] The current theoretical pressure value P in the hydrogen channel is calculated using the following formula: t :

[0035]

[0036] Wherein, m0 represents the initial mass of hydrogen in the hydrogen channel at the initial moment when the fuel cell system enters the hydrogen pressure maintenance state; m1 represents the mass of hydrogen diffused from the proton exchange membrane to the air channel within the preset time, which is calculated by the following formula:

[0037]

[0038] Represents the diffusion coefficient of hydrogen molecules through the proton exchange membrane; represents the diffusion rate of hydrogen; represents the hydrogen concentration gradient from the hydrogen channel to the air channel; t represents the preset time; S represents the diffusion area of ​​hydrogen in the hydrogen channel;

[0039] m2 represents the mass of hydrogen that has participated in the reaction in the hydrogen channel within the preset time, which is calculated by the following formula:

[0040]

[0041] I represents the reaction current; e represents the charge of the electron; NA represents Avogadro's constant;

[0042]

[0043] V1 is the volume of the air channel, and X is the distance between the hydrogen channel and the air channel.

[0044] Optionally, the step S400 includes:

[0045] S401, calculate the theoretical pressure value P t and the actual pressure value P' t The difference between ΔP, ΔP = P t -P' t ;

[0046] S402, determining whether the ΔP is not greater than a first preset risk value ΔP1, if so, determining that the fuel cell system currently has no hydrogen leakage risk; if not, executing S403;

[0047] S403, determine whether the ΔP is less than a second preset risk value ΔP2, if so, determine that the fuel cell system currently has a small amount of hydrogen leakage risk, and issue an alarm message; if not, determine that the fuel system currently has a large amount of hydrogen leakage risk, and issue an alarm message.

[0048] Optionally, the first preset risk value ΔP1 is smaller than the second preset risk value ΔP2.

[0049] Another aspect of the present invention provides a fuel cell system hydrogen leakage detection device, which executes a fuel cell system hydrogen leakage detection method proposed by the present invention.

[0050] The embodiment of the present invention discloses a method and device for detecting hydrogen leakage in a fuel cell system. First, it is determined whether the fuel cell system begins to enter a hydrogen pressure-maintaining state; then, after the hydrogen pressure-maintaining state is maintained for a preset time, the current actual pressure value in the hydrogen channel is measured, and a preset formula is used to calculate the current theoretical pressure value in the hydrogen channel; finally, the risk level of hydrogen leakage in the fuel cell system is determined based on the difference between the theoretical pressure value and the actual pressure value. The present invention can accurately and reliably determine the leakage of hydrogen by comparing the theoretical pressure value with the actual pressure value. At the same time, the present invention does not require the addition of an additional hydrogen concentration sensor, which can effectively save the cost, mass and volume of the fuel cell system.

[0051] 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 disclosure, nor is it intended to limit the scope of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The above and other objects, features and advantages of the present disclosure will become more apparent through a more detailed description of exemplary embodiments of the present disclosure in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present disclosure.

[0053] Figure 1 A schematic diagram of a flow chart of a method for detecting hydrogen leakage in a fuel cell system provided by an embodiment of the present invention;

[0054] Figure 2 An implementation provided for an embodiment of the present invention Figure 1 Schematic diagram of the process of step S100;

[0055] Figure 3 An implementation provided for an embodiment of the present invention Figure 1 Schematic diagram of the process of step S200;

[0056] Figure 4 A schematic diagram of a hydrogen gas entering an air channel provided by an embodiment of the present invention;

[0057] Figure 5 An implementation provided for an embodiment of the present invention Figure 1 Schematic diagram of the process of step S300;

[0058] Figure 6 An implementation provided for an embodiment of the present invention Figure 1 Schematic diagram of the process of step S400. DETAILED DESCRIPTION

[0059] Embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure 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 disclosure more thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art.

[0060] 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.

[0061] The hydrogen supplied to the anode side of the fuel cell system passes through the gas diffusion layer to the proton exchange membrane (electrolyte membrane) and is decomposed into protons (H + ) and electron (e - ), where protons pass through a proton exchange membrane and combine with oxygen on the cathode side to produce the emission - water.

[0062] Figure 1 A schematic diagram of a fuel cell system hydrogen leakage detection method provided by the embodiment of the present invention is shown in FIG. Figure 1 As shown, the detection method comprises the following steps:

[0063] S100: Determine whether the fuel cell system begins to enter a hydrogen pressure maintenance state.

[0064] After stopping operation, the fuel cell system enters a hydrogen pressure maintenance state, and usually maintains the pressure according to a preset pressure value P0. However, the pressure value will gradually decrease as the pressure maintenance state is maintained for a certain period of time.

[0065] If it is determined that the fuel cell system begins to enter the hydrogen pressure maintenance state, executing step S200;

[0066] Otherwise, S100 is executed again to continue to determine whether the fuel cell system begins to enter the hydrogen pressure maintaining state.

[0067] In one embodiment disclosed in the present invention, Figure 2 As shown, the following sub-steps may be used to implement S100:

[0068] S101, determining whether the fuel cell system is shut down.

[0069] If the fuel cell system is shut down, execute S102; otherwise, execute S101 again to determine whether the fuel cell system is shut down.

[0070] S102: Determine whether the pressure value in the hydrogen channel is within a preset pressure maintenance range.

[0071] After being shut down, the fuel cell system will maintain pressure according to the preset pressure value P0. When entering the pressure maintaining state, the initial pressure value in the hydrogen channel will belong to a smaller range with P0 as the median value. For example, the pressure maintaining range is [P0-0.1, P0+0.1].

[0072] If the pressure value in the hydrogen channel belongs to the preset pressure maintaining range, it means that it is in a normal pressure maintaining state, and step S200 is continued.

[0073] If the pressure value in the hydrogen channel does not fall within the preset pressure-maintaining range, indicating that it is in an abnormal pressure-maintaining state, a warning message of pressure-maintaining failure is issued to notify the staff to check the pressure-maintaining situation.

[0074] S200: After the hydrogen pressure maintaining state is maintained for a preset time, the current actual pressure value in the hydrogen channel is measured.

[0075] In one embodiment disclosed in the present invention, Figure 3 As shown, the following sub-steps may be used to implement step S200:

[0076] S201, starting from the time when the fuel cell system enters the hydrogen pressure maintaining state, the time for maintaining the hydrogen pressure maintaining state is recorded.

[0077] Starting from the start time when the fuel cell system enters the hydrogen pressure maintaining state, the time for maintaining the hydrogen pressure maintaining state is recorded.

[0078] S202: After the hydrogen pressure maintaining state is maintained for a preset time, the current actual pressure value in the hydrogen channel is measured using a pressure sensor.

[0079] After the hydrogen pressure maintenance state lasts for a preset time t (for example, t=5 minutes), the pressure sensor provided in the hydrogen channel is used to measure the current actual pressure value in the hydrogen channel, that is, the actual pressure value when the pressure maintenance time reaches t.

[0080] S300, using a preset formula to calculate the current theoretical pressure value in the hydrogen channel.

[0081] like Figure 4 As shown, there are two forms in which the hydrogen in the hydrogen channel can enter the air channel: 1. It diffuses directly into the air channel through the proton exchange membrane through the gas diffusion layer in the form of hydrogen molecules (H2); 2. Hydrogen decomposes into hydrogen protons (H+) and enters the air channel in the form of protons. In this process, part of the hydrogen is decomposed and consumed.

[0082] The gas in the air channel is usually air, oxygen or nitrogen, and the permeation rate of the above gases in the proton exchange membrane is much lower than that of hydrogen. Therefore, when statistics are performed in a shorter time, the diffusion of the gas in the air channel to the hydrogen channel can be ignored.

[0083] When there is no leakage in the hydrogen channel, the theoretical pressure value of the hydrogen channel after a period of time can be calculated according to the above theory, and the theoretical pressure value should be close to the actual pressure value. However, if there is a leakage in the hydrogen channel, the theoretical pressure value will inevitably be significantly greater than the actual pressure value, and the greater the difference between the two, the more serious the hydrogen leakage.

[0084] In one embodiment disclosed in the present invention, Figure 5 As shown, S300 may be implemented by using the following sub-steps:

[0085] S301, measuring the initial pressure value in the hydrogen channel when the fuel cell system begins to enter the hydrogen pressure maintaining state.

[0086] At the beginning moment when the fuel cell system just enters the hydrogen pressure maintaining state, the initial pressure value in the hydrogen channel is measured by the pressure sensor arranged in the hydrogen channel.

[0087] S302. Calculate the initial hydrogen mass in the hydrogen channel when the fuel cell system begins to enter the hydrogen pressure maintaining state according to the initial pressure value.

[0088] In one embodiment disclosed in the present invention, the initial hydrogen mass m0 can be calculated using the following formula:

[0089]

[0090] Among them, P0 represents the initial pressure value in the hydrogen channel; μ represents the molar mass of hydrogen; V represents the volume of the hydrogen channel; a and b represent preset parameters, a is related to the intermolecular attraction, and b is related to the intermolecular repulsion; R represents the gas constant; T represents the temperature of the current fuel cell stack.

[0091] S303, monitor the temperature of the fuel cell stack in real time through a temperature sensor.

[0092] A temperature sensor is installed at the fuel cell stack of the fuel cell system to measure the temperature of the fuel cell stack in real time.

[0093] S304, calculating the current theoretical pressure value in the hydrogen channel according to the initial pressure value, the initial hydrogen mass and the stack temperature.

[0094] In one embodiment disclosed in the present invention, the current theoretical pressure value P in the hydrogen channel can be calculated using the following formula: t :

[0095]

[0096] Wherein, m0 represents the initial hydrogen mass in the hydrogen channel at the initial moment when the fuel cell system enters the hydrogen pressure maintenance state; m1 represents the mass of hydrogen diffused from the proton exchange membrane to the air channel within the preset time, which is calculated by the following formula:

[0097]

[0098] Represents the diffusion coefficient of hydrogen molecules through the proton exchange membrane; represents the diffusion rate of hydrogen; represents the hydrogen concentration gradient from the hydrogen channel to the air channel; t represents the preset time; S represents the diffusion area of ​​hydrogen in the hydrogen channel;

[0099] m2 represents the mass of hydrogen that has participated in the reaction in the hydrogen channel within the preset time, which is calculated by the following formula:

[0100]

[0101] I represents the reaction current; e represents the charge of the electron; NA represents Avogadro's constant;

[0102]

[0103] Wherein, V1 is the volume of the air channel, and X is the distance between the hydrogen channel and the air channel.

[0104] S400: Determine the risk level of hydrogen leakage of the fuel cell system according to the difference between the theoretical pressure value and the actual pressure value.

[0105] The greater the difference between the theoretical pressure value and the actual pressure value, the greater the risk of hydrogen leakage. Conversely, the greater the difference between the theoretical pressure value and the actual pressure value, the smaller the risk of hydrogen leakage.

[0106] In one embodiment disclosed in the present invention, Figure 6 As shown, step S400 includes the following sub-steps:

[0107] S401, calculate the theoretical pressure value P t and the actual pressure value P' t The difference between ΔP, ΔP = P t -P' t .

[0108] S402, judging whether ΔP is not greater than a first preset risk value ΔP1, that is, ΔP≤ΔP1. If ΔP≤ΔP1, determining that the fuel cell system currently has no hydrogen leakage risk; if ΔP>ΔP1, executing S403.

[0109] S403, determine whether ΔP is less than a second preset risk value ΔP2, that is, ΔP1<ΔP<ΔP2. If ΔP1<ΔP<ΔP2, determine that the fuel cell system currently has a small risk of hydrogen leakage, and issue an alarm message; if ΔP≥ΔP2, determine that the fuel system currently has a large risk of hydrogen leakage, and issue an alarm message. The staff can determine the current risk level of hydrogen leakage based on the content contained in the alarm message.

[0110] In the embodiment disclosed in the present invention, the first preset risk value ΔP1 is smaller than the second preset risk value ΔP2.

[0111] The embodiments of the present invention further disclose a fuel cell system hydrogen leakage detection system, which can execute the detection method disclosed in the aforementioned embodiments.

[0112] The embodiments of the present disclosure 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 selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or technical improvements to the technology in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A method for detecting hydrogen leakage in a fuel cell system, characterized in that: The method comprises: S100, determining whether the fuel cell system has begun to enter a hydrogen pressure maintenance state, If yes, execute S200; otherwise, execute S100 again; S200, after the hydrogen pressure maintaining state reaches a preset time, measuring the current actual pressure value in the hydrogen channel; S300, using a preset formula to calculate the current theoretical pressure value in the hydrogen channel; S400: Determine the risk level of hydrogen leakage of the fuel cell system according to the difference between the theoretical pressure value and the actual pressure value.

2. The detection method according to claim 1, characterized in that: The step S100 includes: S101, determining whether the fuel cell system is shut down, If yes, execute S102; otherwise, execute S101 again; S102, determining whether the pressure value in the hydrogen channel is within a preset pressure maintenance range, If so, execute S200; otherwise, issue a warning message of pressure holding failure.

3. The detection method according to claim 1, characterized in that: The step S200 includes: S201, starting from the fuel cell system entering the hydrogen pressure maintenance state, recording the time of maintaining the hydrogen pressure maintenance state; S202: After the hydrogen pressure maintaining state is maintained for a preset time, the current actual pressure value in the hydrogen channel is measured using a pressure sensor.

4. The detection method according to claim 1, characterized in that: The step S300 includes: S301, measuring the initial pressure value in the hydrogen channel when the fuel cell system begins to enter the hydrogen pressure maintenance state; S302, calculating the initial hydrogen mass in the hydrogen channel when the fuel cell system begins to enter the hydrogen pressure maintaining state according to the initial pressure value; S303, monitoring the temperature of the fuel cell stack in real time through a temperature sensor; S304, calculating the current theoretical pressure value in the hydrogen channel according to the initial pressure value, the initial hydrogen mass and the stack temperature.

5. The detection method according to claim 4, characterized in that: The step S302 includes: The initial hydrogen mass m0 is calculated using the following formula: Among them, P0 represents the initial pressure value in the hydrogen channel; μ represents the molar mass of hydrogen; V represents the volume of the hydrogen channel; a and b represent preset parameters, a is related to the intermolecular attraction, and b is related to the intermolecular repulsion; R represents the gas constant; T represents the temperature of the current fuel cell stack.

6. The detection method according to claim 5, characterized in that: The step S304 includes: The current theoretical pressure value P in the hydrogen channel is calculated using the following formula: t : Wherein, m0 represents the initial mass of hydrogen in the hydrogen channel at the initial moment when the fuel cell system enters the hydrogen pressure maintenance state; m1 represents the mass of hydrogen diffused from the proton exchange membrane to the air channel within the preset time, which is calculated by the following formula: Represents the diffusion coefficient of hydrogen molecules through the proton exchange membrane; represents the diffusion rate of hydrogen; represents the hydrogen concentration gradient from the hydrogen channel to the air channel; t represents the preset time; S represents the diffusion area of ​​hydrogen in the hydrogen channel; m2 represents the mass of hydrogen that has participated in the reaction in the hydrogen channel within the preset time, which is calculated by the following formula: I represents the reaction current; e represents the charge of the electron; NA represents Avogadro's constant; V1 is the volume of the air channel, and X is the distance between the hydrogen channel and the air channel.

7. The detection method according to claim 1, characterized in that: The step S400 includes: S401, calculate the theoretical pressure value P t and the actual pressure value P' t The difference between ΔP, ΔP = P t -P′ t ; S402, determining whether the ΔP is not greater than a first preset risk value ΔP1, if so, determining that the fuel cell system currently has no hydrogen leakage risk; if not, executing S403; S403, determine whether the ΔP is less than a second preset risk value ΔP2, if so, determine that the fuel cell system currently has a small amount of hydrogen leakage risk, and issue an alarm message; if not, determine that the fuel system currently has a large amount of hydrogen leakage risk, and issue an alarm message.

8. The detection method according to claim 7, characterized in that: The first preset risk value ΔP1 is smaller than the second preset risk value ΔP2.

9. A fuel cell system hydrogen leak detection device, characterized in that: The fuel cell system hydrogen leakage detection device implements the detection method according to any one of claims 1-8.

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