CN114824385B - Fuel cell hydrogen supply system and control method - Google Patents

Abstract

The invention relates to the technical field of fuel cells, and discloses a hydrogen supply system of a fuel cell and a control method. The system comprises a control module, at least two ejectors and a fuel cell stack, wherein the ejectors are provided with a first ejection inlet and a second ejection inlet, and the ejectors are used for outputting hydrogen accessed from the first ejection inlet and the second ejection inlet; the anode gas inlet of the fuel cell stack is correspondingly connected with the output end of the ejector, the anode gas outlets of the fuel cell stacks are mutually communicated, and the anode gas outlets of the fuel cell stacks output excessive hydrogen to the second ejection inlets; the control module regulates and controls the hydrogen mixing proportion of the anode gas inlet of the fuel cell stack according to the internal hydrogen humidity of the fuel cell stack. The invention enables hydrogen to circulate among the fuel cell stacks by connecting the fuel cell stacks, and can realize mutual active adjustment among the stacks by utilizing the fuel cell stacks with abnormal adjustment of the fuel cell stacks in normal operation.

Description

Fuel cell hydrogen supply system and control method

Technical field

The invention relates to the technical field of fuel cells, in particular to a fuel cell hydrogen supply system and a control method.

Background technique

Fuel cells have become one of the main ways to utilize hydrogen energy due to their high power density and high energy conversion rate. The fuel cell system includes a hydrogen circulation subsystem, which continuously provides a certain pressure and flow rate of hydrogen to the stack to ensure The stack operates efficiently, and it can be said that the hydrogen circulation system has a great impact on the efficiency, reliability, and life of the fuel cell.

The hydrogen supply system provides excess pure hydrogen to the anode of the fuel cell. After the anode reacts, unreacted hydrogen is usually discharged from the anode exhaust port. The hydrogen gas discharged from the anode of the fuel cell stack usually has three processing methods: flow mode, dead-end mode, and circulation mode. In the flow mode, the hydrogen discharged from the anode directly enters the atmosphere through the exhaust valve, which will cause a waste of hydrogen and pollute the environment; in the dead-end mode, the hydrogen exhaust valve is closed. In this mode, the excess hydrogen can completely react. , but the water vapor generated will continue to accumulate, which can easily cause flooding of the fuel cell and reduce the efficiency and life of the fuel cell; the circulation mode is to transport the unreacted hydrogen to the anode hydrogen inlet again to reuse the hydrogen and improve the efficiency of the fuel cell. Regarding the efficiency of the fuel cell stack, it can be said that the circulation mode is a development direction of the hydrogen supply system.

However, the current circulation mode of the hydrogen supply system uses a single fuel cell stack to circulate hydrogen. The system of a single fuel cell stack cannot achieve active regulation of hydrogen supply. When the gas flow rate decreases, the performance of the ejector also deteriorates. It will decline accordingly. In addition, after the fuel cell stack discharges the hydrogen, it needs to be separated from steam and water. When the hydrogen is transported to the anode inlet of the fuel cell stack again, it must be humidified. There are many processes.

Contents of the invention

The purpose of the present invention is to provide a fuel cell hydrogen supply system and a control method to solve one or more technical problems existing in the prior art, and at least provide a beneficial choice or create conditions.

In the first aspect, a fuel cell hydrogen supply system is provided, including:

At least two ejector, the ejector is configured with a first ejector inlet and a second ejector inlet, the first ejector inlet is used to access a dry hydrogen source, the ejector is used to output from Hydrogen gas introduced into the first injection inlet and the second injection inlet;

There are at least two fuel cell stacks. The anode air inlet of one fuel cell stack is correspondingly connected to the output end of an ejector. The anode air outlets of each fuel cell stack are connected to each other. The fuel cell stacks When a reaction occurs, the anode outlet of the fuel cell stack outputs excess hydrogen to each second injection inlet;

A control module that regulates the hydrogen mixing ratio of the anode air inlet of the fuel cell stack according to the internal hydrogen humidity of the fuel cell stack.

As an improvement of the above embodiment, a first gas flow valve is provided between the first injection inlet and the hydrogen source, and a second gas flow valve is provided between the second injection inlet and the anode gas outlet of the fuel cell stack.

As an improvement to the above embodiment, the fuel cell hydrogen supply system further includes an impedance detection module, which detects the membrane electrode resistance of the fuel cell stack, and the control module determines the internal resistance of the fuel cell stack based on the detected membrane electrode resistance. Hydrogen humidity.

As an improvement of the above embodiment, the anode outlet of the fuel cell stack is provided with an exhaust branch, and the exhaust branch is provided with an exhaust valve.

As an improvement of the above embodiment, a pressure regulator is connected to the first injection inlet, a pressure sensor is provided at the anode air inlet of the fuel cell stack, and the controller regulates the pressure regulator according to the air pressure detection data of the pressure sensor.

As an improvement of the above embodiment, a temperature sensor and a humidity sensor are provided between the first injection inlet and the pressure regulator.

As an improvement to the above embodiment, the anode air inlet and the anode air outlet of the fuel cell stack are respectively provided with humidity sensors, and the control module regulates the anode air inlet of the fuel cell stack based on the humidity detection data of the anode air inlet and the anode air outlet. hydrogen mixing ratio.

In a second aspect, a fuel cell hydrogen supply method is provided, which is implemented by the fuel cell hydrogen supply system of the first aspect. The fuel cell hydrogen supply method includes the following steps:

Obtain the internal hydrogen humidity of each fuel cell stack;

Determine whether the internal hydrogen humidity of the fuel cell stack is within the humidity setting range;

If not, the reaction rates of other fuel cell stacks are adjusted according to the deviation degree of the internal hydrogen humidity of the abnormal fuel cell stack.

As an improvement of the above embodiment, regulating the reaction rates of other fuel cell stacks based on the deviation of the internal hydrogen humidity of the abnormal fuel cell stack specifically includes the following steps:

When the internal hydrogen humidity of the abnormal fuel cell stack is lower than the humidity setting range, control other fuel cell stacks to increase the reaction rate; when the internal hydrogen humidity of the abnormal fuel cell stack is higher than the humidity setting range, control other fuel cell stacks Reduce reaction rate.

As an improvement of the above embodiment, the fuel cell hydrogen supply method further includes the following steps:

The hydrogen mixing ratio of the ejector is adjusted according to the deviation of the internal hydrogen humidity of the fuel cell stack.

The beneficial effects of the present invention are: by connecting multiple fuel cell stacks, hydrogen gas is circulated among multiple fuel cell stacks, thereby eliminating the need for a humidifier and improving the utilization rate of hydrogen. When in an abnormal state, the normally operating fuel cell stack can be used to adjust the abnormal fuel cell stack to achieve active adjustment between each stack.

Description of the drawings

Figure 1 is a schematic structural diagram of the fuel cell hydrogen supply system of the present invention.

Figure 2 is a flow chart of the first embodiment of the fuel cell hydrogen supply method of the present invention.

Figure 3 is a flow chart of the second embodiment of the fuel cell hydrogen supply method of the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the present invention will be further described below with reference to the embodiments and drawings.

Exemplary embodiments will be described in detail herein, examples of which are illustrated in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings refer to the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present disclosure. Rather, they are merely examples of apparatus and methods consistent with aspects of the disclosure as detailed in the appended claims.

In the description of the present invention, it should be understood that orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or position relationships shown in the drawings and are only In order to facilitate the description of the present invention and simplify the description, it is not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be construed as a limitation of the present invention.

In the description of the present invention, several means an indefinite amount, plural means two or more, greater than, less than, exceeding, etc. are understood to exclude the original number, and above, below, within, etc. are understood to include the original number. If there is a description of first and second, it is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of indicated technical features or implicitly indicating the order of indicated technical features. relation. In addition, and/or appearing throughout the text represents three parallel solutions. For example, A and/or B represents the solution that A satisfies, the solution that B satisfies, or the solution that A and B satisfy at the same time.

In the description of the present invention, the terms "comprises", "comprising" or any other variation thereof are intended to cover a non-exclusive inclusion of elements other than those listed, but also the inclusion of other elements not expressly listed.

Referring to Figure 1, Figure 1 shows the specific structure of a fuel cell hydrogen supply system of the present invention. The fuel cell hydrogen supply system includes an ejector 100, a fuel cell stack 200 and a control module 300. The ejector The number of 100 and fuel cell stack 200 is at least two and they are adapted to each other in quantity, specifically:

The ejector 100 is configured with a first ejector inlet and a second ejector inlet. The first ejector inlet is used to access a dry hydrogen source, and the ejector 100 is used to output the ejector from the first ejector inlet and the second ejector inlet. Hydrogen gas connected to the inlet;

The anode air inlet of a fuel cell stack 200 is connected to the output end of an ejector 100. The anode air outlets of each fuel cell stack 200 are connected to each other. When the fuel cell stack 200 reacts, the anode air inlet of the fuel cell stack 200 reacts. The anode gas outlet outputs excess hydrogen to each second injection inlet;

The control module 300 regulates the hydrogen mixing ratio of the anode air inlet of the fuel cell stack 200 according to the internal hydrogen humidity of the fuel cell stack 200 .

The injector 100 is a device that uses a high-speed and high-energy flow (liquid flow, air flow or other material flow) to inject another low-speed, low-energy flow. The jet flows into the mixing chamber through the shrinking nozzle, and is surrounded by the guided jet flow. Due to the mixing effect of the boundary, the inducing jet transfers energy to the induced jet. The mixing zone formed by the mixing gradually expands and fills the entire mixing chamber. After a period of mixing process, the flow becomes almost uniform at the exit of the mixing chamber. The ejector 100 described in this embodiment receives hydrogen gas from different sources through its first ejector inlet and second ejector inlet respectively and performs mixed output.

The fuel cell stack 200 is composed of a plurality of fuel cell units stacked in series. The fuel cell stack 200 is a place where electrochemical reactions occur and is the core part of the fuel cell system (or fuel cell engine). During operation, hydrogen and oxygen are distributed to the bipolar plates of each single cell through the main gas channel of the stack, and are evenly distributed to the electrodes through the bipolar plates. The electrode support contacts the catalyst for electrochemical reaction, and hydrogen and oxygen are generated. The electrochemical reaction will produce water, and appropriate humidity needs to be ensured inside the fuel cell stack 200. However, when excessive hydrogen is input, a large amount of water vapor will be generated, causing flooding of the fuel cell stack 200 and reducing the efficiency and efficiency of the fuel cell stack 200. life.

In actual use, the hydrogen source transports dry hydrogen to the first injection inlet, and each fuel cell stack 200 transports moist hydrogen produced by past reactions to the second injection inlet. The dry hydrogen flowing in at a high speed injects the moist hydrogen gas flowing in at a low speed. The hydrogen gas is fully mixed in the mixing zone of the ejector 100, and the mixed hydrogen gas is output to the anode inlet of the corresponding fuel cell stack 200, so that the fuel cell stack 200 can perform electrochemical reactions. The anode outlets of the fuel cell stacks 200 are connected to each other through pipelines. Each fuel cell stack 200 collects and transports the reacted moist hydrogen to the second injection inlet of each ejector 100. The control module 300 obtains the information from each fuel cell stack. 200, by controlling the flow rate of moist hydrogen into each ejector 100, thereby regulating the hydrogen mixing ratio at the anode inlet of the fuel cell stack 200, to achieve the effect of delivering moist hydrogen to the fuel cell stack 200. By controlling the input amount of hydrogen, the reaction rate of each fuel cell stack 200 can also be controlled. Increasing the input flow rate of hydrogen will speed up the reaction rate of the fuel cell stack 200 and increase the internal humidity of the fuel cell stack 200. On the contrary, the fuel The internal humidity of the battery stack 200 decreases, so that the internal humidity of each fuel cell stack 200 is within the humidity setting range.

Furthermore, a first gas flow valve 410 is provided between the first injection inlet and the hydrogen source, and a second gas flow valve 420 is provided between the second injection inlet and the anode gas outlet of the fuel cell stack 200 .

Correspondingly, the first air flow valve 410 and the second air flow valve 420 are electromagnetic valves. The first air flow valve 410 and the second air flow valve 420 are used to regulate the gas flow of the first injection inlet and the second injection inlet respectively. The control module 300 is respectively connected to the first gas flow valve 410 and the second gas flow valve 420. By controlling the opening degree of the first gas flow valve 410 and/or the second gas flow valve 420, the hydrogen gas mixing ratio of the anode inlet of the fuel cell stack 200 is regulated.

Furthermore, the fuel cell hydrogen supply system also includes an impedance detection module 500. The detection module detects the membrane electrode resistance of the fuel cell stack 200. The control module 300 determines the internal hydrogen humidity of the fuel cell stack 200 based on the detected membrane electrode resistance.

It should be noted that the control module 300 detects the membrane electrode resistance based on the AC impedance testing principle, and determines the internal hydrogen humidity of the fuel cell stack 200 based on the detected membrane electrode resistance. AC impedance is also called electrochemical impedance spectroscopy (EIS). When the electrode system is perturbed by an AC signal with a sinusoidal waveform voltage (current), a corresponding current (voltage) response signal will be generated. These are The signal can be obtained from the impedance or admittance of the electrode. The impedance detection module 500 in this embodiment detects the membrane electrode resistance of the fuel cell stack 200, so that the control module 300 determines the internal hydrogen humidity of the fuel cell stack 200 based on the detected membrane electrode resistance.

For example, small-amplitude sine wave disturbance signals of different frequencies are applied to the fuel cell stack 200, and the equivalent circuit of the membrane electrode is estimated based on the electrode impedance obtained from the relationship between the response of the fuel cell stack 200 and the disturbance signal, and then The dynamic processes and mechanisms involved in the fuel cell stack 200 can be analyzed, and the dynamic parameters of the fuel cell stack 200 can be estimated from the parameter values of relevant components in the equivalent circuit, such as the electrode double layer capacitance and the reaction of the charge transfer process. resistance, diffusion mass transfer process parameters, and internal hydrogen humidity of the fuel cell stack 200, etc.

Furthermore, the anode outlet of the fuel cell stack 200 is provided with an exhaust branch 610 , and the exhaust branch 610 is provided with an exhaust valve 620 . The exhaust branch 610 and the exhaust valve 620 are used to eliminate impurities in the system loop. The exhaust valve 620 is controlled by the control module 300. When the system is operating normally, the exhaust valve 620 is closed. When there are too many impurities in the system pipeline, the exhaust valve 620 is controlled by the control module 300. The module 300 triggers the exhaust valve 620 to conduct, and purges the system pipeline to blow away impurities from the exhaust branch 610 .

Further, a pressure regulator 710 is connected to the first injection inlet, and a pressure sensor 720 is provided at the anode air inlet of the fuel cell stack 200. The controller regulates the pressure regulator 710 based on the air pressure detection data of the pressure sensor 720. The dry hydrogen from the hydrogen source enters the ejector 100 after passing through the pressure regulator 710. The pressure regulator 710 is used to adjust the air pressure of the first ejector inlet so that the hydrogen input pressure is within the range required by the system.

Furthermore, a temperature sensor 800 and a humidity sensor 900 are provided between the first injection inlet and the pressure regulator 710 .

Furthermore, the anode air inlet and the anode air outlet of the fuel cell stack 200 are respectively provided with humidity sensors 900, and the control module 300 regulates the hydrogen mixing at the anode air inlet of the fuel cell stack 200 based on the humidity detection data of the anode air inlet and the anode air outlet. Proportion.

In actual use, the control module 300 regulates the hydrogen mixing ratio of the anode air inlet of the fuel cell stack 200 based on the humidity difference between the anode air inlet and the anode air outlet. When the humidity difference between the anode air inlet and the anode air outlet of the current fuel cell stack 200 exceeds the preset value of the humidity difference, the humidity of the anode air outlet is greater than the humidity of the anode air inlet, which increases the radiation corresponding to other fuel cell stacks 200 The degree of opening of the second injection inlet of the ejector 100 of the current fuel cell stack 200 can be further reduced to allow other fuel cell stacks 200 to consume humidified hydrogen, or the degree of opening of the second injection inlet of the ejector 100 of the current fuel cell stack 200 can be further reduced. Reduce the reaction rate of the current fuel cell stack 200; when the humidity difference between the anode air inlet and the anode air outlet of the current fuel cell stack 200 exceeds the preset value of the humidity difference, the humidity of the anode air outlet is less than the humidity of the anode air inlet, The opening degree of the second injection inlet of the ejector 100 corresponding to the current fuel cell stack 200 is increased, so that the current fuel cell stack 200 consumes moist hydrogen.

The working principle of the fuel cell hydrogen supply system of the present invention will be described in detail below with reference to specific steps.

Referring to Figures 1 and 2, Figure 2 shows the specific steps of a fuel cell hydrogen supply method of the present invention. The fuel cell hydrogen supply method includes the following steps:

Step S1: Obtain the internal hydrogen gas humidity of each fuel cell stack 200.

Among them, the membrane electrode resistance can be detected through the AC impedance testing principle.

Step S2: Determine whether the internal hydrogen humidity of the fuel cell stack 200 is within the humidity setting range. If yes, execute step S3; if not, execute step S4.

Step S3: Maintain the reaction rate of each fuel cell stack 200.

Step S4: Regulate the reaction rates of other fuel cell stacks 200 according to the deviation degree of the internal hydrogen humidity of the abnormal fuel cell stack 200.

Further, regulating the reaction rates of other fuel cell stacks 200 according to the deviation degree of the internal hydrogen humidity of the abnormal fuel cell stack 200 specifically includes the following steps:

When the internal hydrogen humidity of the abnormal fuel cell stack 200 is lower than the humidity setting range, other fuel cell stacks 200 are controlled to increase the reaction rate; when the internal hydrogen humidity of the abnormal fuel cell stack 200 is higher than the humidity setting range, other fuels are controlled The battery stack 200 reduces the reaction rate.

Correspondingly, when the fuel cell hydrogen supply system performs the above method, when the judgment result is that the internal hydrogen humidity of each fuel cell stack 200 is within the humidity setting range, the ejector 100 corresponding to each fuel cell stack 200 will The air intake flow rate of the second injection inlet is determined according to the operating power of each fuel cell stack 200 and is independent of each other. It can be controlled by adjusting the opening degree of each second air flow valve 420; when the judgment result is that there is When the humidity of the hydrogen gas at the anode inlet of the fuel cell stack 200 is low, the reaction rate of other fuel cell stacks 200 in the normal state is increased, and the flow rate of the humidified hydrogen discharged from the fuel cell stack 200 in the normal state is increased, thereby increasing the inflow of the hydrogen gas. The flow rate of humidified hydrogen in the ejector 100; when the judgment result is that the hydrogen humidity in the anode inlet of the fuel cell stack 200 is high, the reaction rate of other fuel cell stacks 200 in the normal state is reduced, and the reaction rate of the fuel cell stack 200 in the normal state is reduced. The stack 200 discharges the flow rate of humid hydrogen gas, thereby reducing the flow rate of humid hydrogen gas flowing into the ejector 100 .

Further, as shown in Figure 3, the above fuel cell hydrogen supply method also includes the following steps:

Step S5: Adjust the hydrogen mixing ratio of the ejector 100 according to the degree of deviation of the internal hydrogen humidity of the fuel cell stack 200.

Correspondingly, when the determination result is that the hydrogen gas humidity at the anode inlet of the fuel cell stack 200 is low, the opening degree of the second air flow valve 420 is adjusted to increase the third ejector 100 corresponding to the fuel cell stack 200 . The air inlet flow rate of the second ejector inlet increases the flow rate of the wet hydrogen gas flowing into the ejector 100; when the judgment result is that there is a high humidity of hydrogen gas at the anode air inlet of the fuel cell stack 200, by adjusting the second air flow valve 420 The degree of opening is used to reduce the air intake flow rate of the second injection inlet of the ejector 100 corresponding to the fuel cell stack 200 and to reduce the flow rate of wet hydrogen gas flowing into the ejector 100 . Through the above method, mutual active control between the fuel cell stacks 200 is achieved.

The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention. should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims (7)

1. A hydrogen supply system for a fuel cell, comprising:

the device comprises at least two ejectors, wherein the ejectors are provided with a first ejecting inlet and a second ejecting inlet, the first ejecting inlet is used for being connected with a dry hydrogen source, and the ejectors are used for outputting hydrogen connected from the first ejecting inlet and the second ejecting inlet;

the fuel cell comprises at least two fuel cell stacks, wherein an anode gas inlet of one fuel cell stack is correspondingly connected with an output end of an ejector, anode gas outlets of the fuel cell stacks are mutually communicated, and when the fuel cell stacks react, the anode gas outlets of the fuel cell stacks output excessive hydrogen to the second ejection inlets;

the control module regulates and controls the hydrogen mixing proportion of an anode gas inlet of the fuel cell stack according to the internal hydrogen humidity of the fuel cell stack;

the method for regulating and controlling the hydrogen mixing proportion of the anode gas inlet of the fuel cell stack according to the internal hydrogen humidity of the fuel cell stack comprises the following steps: when the internal hydrogen humidity of the abnormal fuel cell stack is lower than a humidity setting range, controlling other fuel cell stacks to improve the reaction rate; when the internal hydrogen humidity of the abnormal fuel cell stack is higher than a humidity setting range, controlling other fuel cell stacks to reduce the reaction rate;

the controlling of other fuel cell stacks to increase the reaction rate includes: increasing the opening degree of a second injection inlet of the injector corresponding to other fuel cell stacks, or further reducing the opening degree of the second injection inlet of the injector of the current abnormal fuel cell stack;

the controlling of the other fuel cell stacks to reduce the reaction rate includes: and increasing the opening degree of a second injection inlet of the injector corresponding to the current abnormal fuel cell stack.

2. The fuel cell hydrogen supply system according to claim 1, wherein a first air flow valve is provided between the first injection inlet and the hydrogen source, and a second air flow valve is provided between the second injection inlet and an anode gas outlet of the fuel cell stack.

3. The fuel cell hydrogen supply system according to claim 1, further comprising an impedance detection module that detects a membrane electrode resistance of the fuel cell stack, wherein the control module determines an internal hydrogen humidity of the fuel cell stack based on the detected membrane electrode resistance.

4. The fuel cell hydrogen supply system according to claim 1, wherein an anode gas outlet of the fuel cell stack is provided with a gas discharge branch provided with a gas discharge valve.

5. The hydrogen supply system of claim 1, wherein the first injection inlet is connected with a pressure regulator, a pressure sensor is disposed at an anode gas inlet of the fuel cell stack, and the control module regulates the pressure regulator according to pressure detection data of the pressure sensor.

6. The fuel cell hydrogen supply system according to claim 5, wherein a temperature sensor and a humidity sensor are provided between the first injection inlet and the pressure regulator.

7. The hydrogen supply system of claim 1, wherein the anode gas inlet and the anode gas outlet of the fuel cell stack are respectively provided with a humidity sensor, and the control module regulates the hydrogen mixing ratio of the anode gas inlet of the fuel cell stack according to the humidity detection data of the anode gas inlet and the anode gas outlet;

the method for regulating and controlling the hydrogen mixing proportion of the anode gas inlet of the fuel cell stack according to the humidity detection data of the anode gas inlet and the anode gas outlet comprises the following steps:

under the condition that the humidity difference between an anode air inlet and an anode air outlet of the current fuel cell stack exceeds a preset humidity difference value, the humidity of the anode air outlet is larger than the humidity of the anode air inlet, and the opening degree of a second injection inlet of an injector corresponding to other fuel cell stacks is increased so as to enable the other fuel cell stacks to consume wet hydrogen, or the opening degree of the second injection inlet of the injector of the current fuel cell stack is further reduced so as to enable the current fuel cell stack to reduce the reaction rate;

and under the condition that the humidity difference between the anode air inlet and the anode air outlet of the current fuel cell stack exceeds a preset humidity difference value, the humidity of the anode air outlet is smaller than that of the anode air inlet, and the opening degree of a second injection inlet of an injector corresponding to the current fuel cell stack is increased so as to enable the current fuel cell stack to consume wet hydrogen.