Air flow detection method for fuel cell system and fuel cell system

Abstract

The present application discloses an air flow detection method for a fuel cell system, the fuel cell system comprising: an electric pile, an air compressor and an intercooler, wherein the intercooler is arranged between the electric pile and the air compressor, the air compressor is configured to supply air to the electric pile through the intercooler, the method comprising the following steps: obtaining a first pressure P1 of air entering the intercooler; obtaining a first temperature T1 of air entering the intercooler; obtaining an input pressure P2 of air entering the electric pile; calculating an input air flow rate of the electric pile by using the first pressure P1, the input pressure P2 and the first temperature T1, wherein the input air flow rate is represented as: wherein, wherein, C1 is a flow coefficient of an air inlet pipeline in communication with the electric pile, S1 is a flow area of the air inlet pipeline, R0 is a gas constant of air, and K is a specific heat capacity ratio of air.

Description

Technical Field

[0001] This application relates to the field of fuel cell technology, and in particular to an air flow detection method for a fuel cell system, a fuel cell system, and a computer program product. Background Technology

[0002] With the development of clean energy technologies, fuel cell systems have been widely used as power sources in many industries (e.g., electric vehicles). In a fuel cell system, hydrogen is supplied as a fuel gas to the anode side of the stack (which may include multiple fuel cell units), and air is supplied as an oxidizing gas to the cathode side of the stack. Electricity is generated through an electrochemical reaction between hydrogen and oxygen in the air within the stack.

[0003] In existing fuel cell systems, an air compressor is typically used to supply air to the cathode side. The air compressor receives air from the atmosphere, compresses it, cools it via an intercooler, and then delivers it to the fuel cell stack. After the air compressor, there are usually two lines: one connected to the fuel cell stack to provide the oxygen required for the reaction, and the other connected via a bypass line to the exhaust line to react quickly in case of impending air pressure anomalies. To effectively control the operation of the air compressor, an air flow meter is installed before it. Additionally, to ensure sufficient air enters the fuel cell stack, another flow meter is installed after the air compressor and before the stack (specifically before the intercooler) to measure the air flow rate entering the stack in real time, thereby calibrating the excess oxygen coefficient. When the oxygen entering the stack is insufficient, the operating speed of the air compressor needs to be increased to increase the air flow rate into the stack.

[0004] Therefore, existing fuel cell systems typically require at least two air flow meters. However, the high cost of air flow meters correspondingly increases the overall cost of the fuel cell system. Furthermore, the more air flow meters required, the more design, installation, and maintenance issues arise.

[0005] Therefore, existing methods for detecting airflow in fuel cell systems and the fuel cell systems themselves need to be improved. Summary of the Invention

[0006] The purpose of this application is to provide an air flow detection method for a fuel cell system and a fuel cell system, so as to overcome at least one of the above-mentioned technical problems.

[0007] Therefore, according to one aspect of this application, an air flow detection method for a fuel cell system is provided, the fuel cell system comprising: a fuel cell stack, an air compressor, and an intercooler, wherein the intercooler is disposed between the fuel cell stack and the air compressor, the air compressor being configured to supply air to the fuel cell stack via the intercooler, the air flow detection method comprising the following steps:

[0008] The first pressure P1 of the air entering the intercooler is obtained;

[0009] The first temperature T1 of the air entering the intercooler is obtained;

[0010] The input pressure P2 of the air entering the fuel cell stack is obtained;

[0011] The input air flow rate entering the fuel cell stack is calculated using the first pressure P1, the input pressure P2, and the first temperature T1. The input air flow rate It is represented as:

[0012]

[0013] in,

[0014] Wherein, C1 is the flow coefficient of the air intake pipe connected to the fuel cell stack, S1 is the flow area of ​​the air intake pipe, R0 is the gas constant of air, and K is the specific heat capacity ratio of air.

[0015] According to another aspect of this application, a fuel cell system is provided, comprising: a fuel cell stack; an air compressor; an intercooler disposed between the fuel cell stack and the air compressor, wherein the fuel cell stack, the intercooler and the air compressor are connected via an intake pipe, the air compressor being configured to supply air to the fuel cell stack via the intercooler; and a processor configured to perform the air flow detection method as described above.

[0016] According to another aspect of this application, a computer program product is provided, comprising instructions that, when executed by a processor, cause the processor to perform the steps of the air flow detection method as described above.

[0017] According to the technical solution of this application, during the operation of the fuel cell system, the input airflow rate entering the stack can be calculated based on the pressure rating and efficiency characteristics of the air compressor using aerodynamic knowledge. Therefore, the calculated airflow rate value can replace the airflow rate value measured by the actual airflow meter, thereby eliminating the need for the airflow meter installed after the air compressor in the prior art. This reduces the cost of the fuel cell system and simplifies its structure and subsequent maintenance while providing reliable detection results. Attached Figure Description

[0018] Exemplary embodiments of this application will now be described in detail with reference to the accompanying drawings. It should be understood that the embodiments described below are for illustrative purposes only and are not intended to limit the scope of this application. In the accompanying drawings:

[0019] Figure 1 This is a schematic block diagram illustrating a fuel cell system according to an embodiment of this application;

[0020] Figure 2 This is a schematic flowchart illustrating an airflow detection method for a fuel cell system according to an embodiment of this application;

[0021] Figure 3 This is a schematic diagram showing the relationship between airflow, speed, and pressure ratio of an air compressor;

[0022] Figure 4 This is a schematic diagram illustrating the process for calculating the air pressure entering the intercooler;

[0023] Figure 5 This is a schematic diagram showing the relationship between airflow, speed, and efficiency of an air compressor;

[0024] Figure 6 This is a schematic diagram illustrating the process used to calculate the efficiency of an air compressor. Detailed Implementation

[0025] The preferred embodiments of this application are described in detail below with reference to examples. Those skilled in the art should understand that these exemplary embodiments do not imply any limitation on this application. The exemplary embodiments of this application do not imply that the air flow detection method for a fuel cell system cannot include other steps, nor that the fuel cell system of this application cannot include other modules or components. Unless otherwise specified, features in the embodiments of this application can be combined with each other. It should be understood that the number, position, and order of steps in the drawings are not intended to limit this application.

[0026] The terms “first”, “second”, etc., used in this application are only used to distinguish different objects, and not to describe a specific order.

[0027] The following reference Figures 1 to 6 This application describes a fuel cell system and an air flow detection method for a fuel cell system according to embodiments of the present application.

[0028] like Figure 1 As shown, a fuel cell system 100 according to an embodiment of this application includes a fuel cell stack 10. The fuel cell stack 10 typically includes multiple fuel cell units stacked together, each fuel cell unit including an anode plate, a cathode plate, and a membrane electrode assembly sandwiched between the two plates. An electrochemical reaction occurs when hydrogen and air are supplied to the anode and cathode sides of each fuel cell unit, respectively, thereby outputting electrical energy. The fuel cell stack 10 can be a structure common in the art, and therefore will not be described in further detail herein.

[0029] The fuel cell system 100 also includes an air compressor 20 configured to supply air at a desired pressure and flow rate to the fuel cell stack 10, thereby providing oxygen for the electrochemical reactions within the stack 10. Additionally, the fuel cell system 100 may include an intake line 11 and an exhaust line 12 communicating with the fuel cell stack 10, and a bypass line 13 disposed between the intake line 11 and the exhaust line 12. The air compressor 20 receives air from the atmosphere, compresses it, and delivers it to the fuel cell stack 10 via the intake line 11. Preferably, an air filter 50 is also provided upstream of the air compressor 20 (e.g., at the inlet of the intake line 11) to filter out harmful gases, particulate matter, and other impurities. The air entering the fuel cell stack 10 reacts with hydrogen introduced from the anode side of the fuel cell stack 10 within the stack 10, and the remaining gas after the reaction is discharged into the atmosphere via the exhaust line 12. Preferably, a silencer 90 is provided at the outlet of the exhaust line 12 to effectively reduce noise. The bypass line 13 is located downstream of the air compressor 20 to allow for a rapid response in case of abnormal air pressure (e.g., when the air compressor 20 is about to surge). Figure 1 As shown, a bypass valve 81 for controlling the opening and closing of the bypass pipeline 13 is provided in the bypass pipeline 13, and a pressure regulating valve 82 for adjusting the gas pressure in the exhaust pipeline 12 is provided in the exhaust pipeline 12. Additionally, an intake shut-off valve 71 can be provided in the intake pipeline 11, and an exhaust shut-off valve 72 can be provided in the exhaust pipeline 12. The bypass valve 81, pressure regulating valve 82, intake shut-off valve 71, and exhaust shut-off valve 72 described above can adopt various structural forms; therefore, the specific structures of these valves will not be described in detail herein.

[0030] After being compressed by the air compressor 20, the temperature of the air rises sharply. To maintain the cathode side of the fuel cell stack 10 within a suitable temperature range, the fuel cell system 100 also includes an intercooler 30 for cooling the air compressed by the air compressor 20. The intercooler 30 is disposed between the fuel cell stack 10 and the air compressor 20, and a bypass line 13 is located between the air compressor 20 and the intercooler 30. The fuel cell stack 10, the intercooler 30, and the air compressor 20 are connected by an intake line 11, so that the air supplied by the air compressor 20 can be delivered to the fuel cell stack 10 after being cooled by the intercooler 30.

[0031] like Figure 1 As shown, the fuel cell system 100 may further include a first pressure sensor 41, which is disposed upstream of the air compressor 20 and configured to measure the intake pressure P0 of the air entering the air compressor 20. For example, the first pressure sensor 41 may be disposed between the air filter 50 and the air compressor 20.

[0032] The fuel cell system 100 may also include a first thermometer 44 disposed upstream of the air compressor 20 and configured to measure the intake temperature T0 of the air entering the air compressor 20. For example, to accurately measure the intake temperature of the air entering the air compressor 20, the first thermometer 44 may be disposed at the inlet of the air compressor 20.

[0033] The fuel cell system 100 may also include an air flow meter 60, which is disposed upstream of the air compressor 20 and configured to measure the initial air flow of the air compressor 20. For example, an air flow meter 60 may be positioned between a first pressure sensor 41 and a first thermometer 44.

[0034] The fuel cell system 100 may also include a second pressure sensor 42 disposed between the fuel cell stack 10 and the intercooler 30 (particularly between the fuel cell stack 10 and the intake shut-off valve 71) and configured to measure the input pressure P2 of the air entering the fuel cell stack 10. Additionally, a third pressure sensor 43 may be disposed in the exhaust line 12 to measure the exhaust pressure in the exhaust line 12.

[0035] like Figure 1 As shown, the fuel cell system 100 of this application may further include a processor 12 and a memory 14, wherein the processor 12 can access the memory 14 and can be configured to perform the air flow detection method described in detail below.

[0036] The processor 12 can communicate with the air compressor 20, the air flow meter 60, the first pressure sensor 41, the first thermometer 44, and the second pressure sensor 42 to obtain the initial air flow of the air compressor 20. The air intake pressure P0, air intake temperature T0, and input pressure P2 of the air entering the fuel cell stack 10 are specified. The processor 12 can be a general-purpose processor, digital signal processor, application-specific integrated circuit, field-programmable gate array, or other programmable logic device.

[0037] The memory 14 can store curves of the pressure characteristics and efficiency features of the air compressor 20. The memory 14 can be implemented as various computer-readable storage media, such as read-only memory (ROM), random access memory (RAM), portable hard disk, flash drive, or optical disk, etc., which can store program code. The memory 11 and the processor 13 can be integrated into a single circuit or piece of hardware, or they can be manufactured separately.

[0038] The processor 12 can access the memory 14 and use the obtained parameters to calculate the input air flow rate into the fuel cell stack 10. The memory 11 can store a computer program containing multiple instructions, which, when executed by the processor 13, can cause the processor 13 to perform all or part of the steps of the air flow detection method of this application. In a fuel cell vehicle, the processor 12 can be implemented as a fuel cell unit (FCU), a vehicle control unit (VCU), or a part thereof.

[0039] To simplify the description, in Figure 1 The configuration of the cathode side of the fuel cell system 100 is shown and described only above, while the configuration of the anode side of the fuel cell system 100 is not shown or described. It should be noted that the fuel cell system 100 of this application may include various existing or future-developed configurations located on its anode side, while still being suitable for realizing the inventive concept of this application.

[0040] The following reference Figures 2 to 6 Here is a description of an airflow detection method 200 according to an embodiment of this application.

[0041] like Figure 2 As shown, at step 210, the first pressure P1 of the air entering the intercooler 30 is obtained.

[0042] The pressure ratio PR of an air compressor can be determined by the air compressor's intake pressure P0, speed N, and air flow rate. (It can be determined by mass flow rate or volumetric flow rate). The pressure ratio PR refers to the ratio of the gas pressure at the outlet to the gas pressure at the inlet of the air compressor, and the pressure ratio PR is determined by the rotational speed N and the air flow rate. The function of [the compressor]. Therefore, for an air compressor, a curve indicating the compressor's pressure characteristics can be provided. Conversely, given the air compressor's speed N and air flow rate... In this case, the pressure ratio PR can be determined based on the curve, for example, through interpolation. Then, based on the air compressor's intake pressure, the output air pressure after compression by the air compressor can be calculated.

[0043] Therefore, according to one embodiment of this application, in the absence of a pressure sensor at the inlet of the intercooler 30, the pressure ratio characteristics of the air compressor 20 can be used to determine the pressure of the air compressor 20, specifically the intake pressure P0 and the initial airflow rate. Given the rotational speed N, the initial air pressure P1 entering the intercooler 30 is calculated. The intake pressure P0 can be measured by a first pressure sensor 41 located upstream of the air compressor 20, and the initial airflow rate. It can be measured by the air flow meter 60, and the speed N can be provided by the compressor controller.

[0044] Figure 3 The relationship between the air compressor's speed, air flow rate, and pressure ratio is shown. For example... Figure 3 As shown, the left vertical axis represents the rotational speed N of the air compressor 20, the right vertical axis represents the pressure ratio PR of the air compressor 20, and the horizontal axis represents the initial airflow of the air compressor 20. Therefore, the intake pressure P0 of the air entering the air compressor 20 and the initial air flow rate of the air compressor 20 are obtained. Given a rotational speed N, the initial airflow can be utilized. And rotational speed N, based on Figure 3 The pressure ratio characteristic curve of the air compressor 20 shown is used to determine the pressure ratio PR of the air compressor 20, for example, through interpolation. Then, the first pressure P1 can be calculated using the pressure ratio PR and the intake pressure P0, where the first pressure P1 is expressed as:

[0045] P1 = PR * P0.

[0046] Therefore, step 210 may further include: obtaining the intake pressure P0 of the air entering the air compressor 20 and the initial air flow rate of the air compressor 20. and rotational speed N; utilizing initial airflow Given the rotational speed N, and based on the pressure ratio characteristics of the air compressor 20, the pressure ratio PR of the air compressor 20 is determined; and using the pressure ratio PR and the intake pressure P0, the first pressure P1 is calculated, where the first pressure P1 is expressed as:

[0047] P1 = PR**P0.

[0048] The process described in step 210 can be simplified as follows: Figure 4As shown in the diagram. It should be noted that in step 210, the first pressure P1 can also be obtained by other means, for example, by measuring the first pressure P1 using a pressure sensor. Obviously, this would increase the cost of the fuel cell system 100.

[0049] At step 220, the first temperature T1 of the air entering the intercooler 30 is obtained.

[0050] The compression of air by an air compressor causes a sharp increase in air temperature. The efficiency η of an air compressor reflects its energy losses and can be determined by its aerodynamic and thermodynamic parameters. Specifically, efficiency η is the air compressor's rotational speed N and airflow rate. The function of [the compressor's efficiency] is thus provided. Therefore, for an air compressor, a curve indicating its efficiency characteristics can be obtained. Conversely, given the air compressor's rotational speed N and airflow rate... In this case, the value of efficiency η can be determined based on the curve, for example, through interpolation. On the other hand, efficiency η is also a function of the inlet temperature T0, inlet pressure P0, outlet temperature (e.g., first temperature T1), and outlet pressure (e.g., first pressure P1) of a flow path. Therefore, in the embodiments of this application, based on the air compressor's inlet temperature T0, efficiency η, inlet pressure P0, and first pressure P1, the first temperature T1 of the air compressed by the air compressor and output to the intercooler 30 can be calculated.

[0051] Therefore, according to one embodiment of this application, without installing a temperature sensor at the inlet of the intercooler 30, the efficiency relationship of the air compressor 20 can be determined by utilizing the air compressor 20's intake air temperature T0 and initial air flow rate. Using the rotational speed N, intake pressure P0, and first pressure P1, the first temperature T1 of the air entering the intercooler 30 is calculated.

[0052] Figure 5 The relationship between air compressor speed, airflow rate, and efficiency is shown. For example... Figure 5 As shown, the left vertical axis represents the rotational speed N of the air compressor 20, the right vertical axis represents the efficiency η of the air compressor 20, and the horizontal axis represents the initial airflow of the air compressor 20. Therefore, in obtaining the initial air flow rate of the air compressor 20 Given a rotational speed N, the initial airflow can be utilized. Given the rotational speed N, and based on the efficiency characteristics of the air compressor 20, the efficiency η of the air compressor 20 is determined, for example, through interpolation. Then, using the efficiency η, the intake pressure P0, the first pressure P1, and the intake temperature T0, the first temperature T1 of the air entering the intercooler 30 can be calculated, where the first temperature T1 is expressed as:

[0053] Where K is the specific heat capacity of air.

[0054] Therefore, step 220 may further include: obtaining the intake temperature T0 of the air entering the air compressor 20; utilizing the initial air flow rate Given the rotational speed N, and based on the efficiency characteristics of the air compressor 20, the efficiency η of the air compressor 20 is determined; and using the efficiency η, the intake temperature T0, the intake pressure P0, and the first pressure P1, the first temperature T1 is calculated, where the first temperature T1 is expressed as:

[0055]

[0056] The process described in step 220 can be simplified as follows: Figure 6 As shown in the diagram. It should be noted that in step 220, the first temperature T1 can also be obtained in other ways, for example, by setting a temperature sensor to measure the first temperature T1. Of course, this would also increase the cost of the fuel cell system 100.

[0057] It should be pointed out that, such as Figure 3 and Figure 5 The pressure ratio and efficiency characteristics of the air compressor 20 shown can be represented in the form of a lookup table or curve, and the pressure ratio PR and efficiency η of the air compressor can be obtained by interpolation.

[0058] For a flow path, the air flow rate at the endpoint can be calculated using a throttling model, taking into account the air pressure and temperature at the starting point, the flow area and flow coefficient of the pipeline, and the air pressure at the endpoint. This calculation process is known in the field and will not be elaborated upon here.

[0059] Therefore, the airflow detection method 200 of this application may further include steps 230 and 240. In step 230, the input pressure P2 of the air entering the fuel cell stack 10 is obtained. The input pressure P2 can be measured by a second pressure sensor 42 disposed between the intercooler 30 and the fuel cell stack 10. In step 240, the input airflow entering the fuel cell stack 10 is calculated using the first pressure P1, the input pressure P2, and the first temperature T1. Among them, the input air flow It is represented as:

[0060]

[0061] Where C1 is the flow coefficient of the air intake pipe 11 connected to the fuel cell stack 10, S1 is the flow area of ​​the air intake pipe 11, R0 is the gas constant of air, and K is the specific heat capacity ratio of air. It should be noted that, considering whether the ratio of the first pressure P1 to the input pressure P2 reaches a critical state, the values ​​in the above formula are also adjusted. The correction has been made, as shown below:

[0062]

[0063] Therefore, by using the above steps, the input air flow rate of the air entering the fuel cell stack 10 can be detected using only the air flow meter 60 installed upstream of the air compressor 20. Therefore, the air flow meter installed after the air compressor in existing fuel cell systems can be omitted, thereby reducing the cost of the fuel cell system and simplifying its structure and subsequent maintenance.

[0064] The above describes the air flow detection method for a fuel cell system according to this application. The implemented method can also be implemented as a computer program product, which may include instructions (e.g., computer executable code) that, when executed by a processor, cause the processor to perform all or part of the steps of the above-described air flow detection method.

[0065] The present application has been described in detail above with reference to specific embodiments. Obviously, the above description and the embodiments shown in the accompanying drawings should be understood as exemplary and not as limiting the present application. Those skilled in the art can make various modifications or alterations without departing from the spirit of the present application, and such modifications or alterations do not depart from the scope of the present application.

Claims

1. An airflow detection method (200) for a fuel cell system (100), the fuel cell system (100) comprising: A fuel cell stack (10), an air compressor (20), and an intercooler (30), wherein the intercooler (30) is disposed between the fuel cell stack (10) and the air compressor (20), the air compressor (20) being configured to supply air to the fuel cell stack (10) via the intercooler (30), and the air flow detection method (200) comprising the following steps: The first pressure P1 of the air entering the intercooler (30) is obtained; The first temperature T1 of the air entering the intercooler (30) is obtained; The input pressure P2 of the air entering the fuel cell stack (10) is obtained; The input air flow rate entering the fuel cell stack (10) is calculated using the first pressure P1, the input pressure P2, and the first temperature T1. The input air flow rate It is represented as: in, Wherein, C1 is the flow coefficient of the air intake pipe (11) connected to the fuel cell stack (10), S1 is the flow area of ​​the air intake pipe (11), R0 is the gas constant of air, and K is the specific heat ratio of air.

2. The airflow detection method (200) according to claim 1, wherein, The steps for obtaining the first pressure P1 of the air entering the intercooler (30) include: The intake pressure P0 of the air entering the air compressor (20) and the initial air flow rate of the air compressor (20) are obtained. and rotational speed N; Using the initial airflow Based on the pressure ratio characteristics of the air compressor (20) and the rotational speed N, the pressure ratio PR of the air compressor (20) is determined; Using the pressure ratio PR and the intake pressure P0, the first pressure P1 is calculated, wherein the first pressure P1 is expressed as: P1 = PR * P0.

3. The airflow detection method (200) according to claim 2, wherein, The steps for obtaining the first temperature T1 of the air entering the intercooler (30) include: The intake temperature T0 of the air entering the air compressor (20) is obtained; Using the initial airflow Based on the efficiency characteristics of the air compressor (20) and the rotational speed N, the efficiency η of the air compressor (20) is determined; Using the efficiency η, the intake temperature T0, the intake pressure P0, and the first pressure P1, the first temperature T1 is calculated, wherein the first temperature T1 is expressed as:

4. The airflow detection method (200) according to claim 3, wherein, The compression ratio and efficiency characteristics are represented as lookup tables or curves, respectively, and the compression ratio PR and efficiency η are obtained through interpolation.

5. The airflow detection method (200) according to claim 3, wherein, The intake pressure P0 and the intake temperature T0 are measured upstream of the air compressor (20).

6. The airflow detection method (200) according to claim 1, wherein, The input pressure P2 is measured between the intercooler (30) and the fuel cell stack (10).

7. A fuel cell system (100), comprising: fuel cell stack (10); Air compressor (20); An intercooler (30) is disposed between the fuel cell stack (10) and the air compressor (20), wherein the fuel cell stack (10), the intercooler (30) and the air compressor (20) are connected by an intake pipe (11), and the air compressor (20) is configured to supply air to the fuel cell stack (10) via the intercooler (30); and The processor (12) is configured to perform the air flow detection method (200) according to any one of claims 1 to 6.

8. The fuel cell system (100) according to claim 7, wherein, The fuel cell system (100) also includes: A first pressure sensor (41) is disposed upstream of the air compressor (20) and configured to measure the intake pressure P0 of the air entering the air compressor (20); A first thermometer (44), which is located upstream of the air compressor (20) and configured to measure the intake temperature T0 of the air entering the air compressor (20); and A second pressure sensor (42) is disposed between the fuel cell stack (10) and the intercooler (30) and is configured to measure the input pressure P2 of the air entering the fuel cell stack (10).

9. The fuel cell system (100) according to claim 8, wherein, The fuel cell system (100) also includes: An air flow meter (60) is disposed upstream of the air compressor (20) and configured to measure the initial air flow of the air compressor (20).

10. The fuel cell system (100) according to claim 7, wherein, The fuel cell system (100) also includes: The memory (14) is configured to store the pressure characteristics and efficiency features of the air compressor (20), and the processor (12) is configured to access the memory (14).

11. A computer program product comprising instructions that, when executed by a processor, cause the processor to perform the steps of the airflow detection method (200) according to any one of claims 1 to 6.

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