Hydrogen Discharge Method, Device, Electronic Device and Readable Storage Medium for Fuel Cell System

Abstract

The present invention provides a hydrogen discharge method, device, electronic device and readable storage medium for a fuel cell system, relating to the technical field of fuel cell systems, including determining an exhaust speed and an exhaust density according to the current exhaust volume flow rate of a hydrogen discharge valve in a hydrogen circulation path; determining a target constant according to the exhaust speed and the exhaust density; calculating a real-time nitrogen concentration in the hydrogen circulation path based on the target constant; if the real-time nitrogen concentration meets a preset hydrogen discharge requirement, controlling the hydrogen discharge valve to open, and repeating the steps of determining the exhaust speed and the exhaust density according to the current exhaust volume flow rate of the hydrogen discharge valve in the hydrogen circulation path until the real-time nitrogen concentration meets a preset nitrogen concentration threshold and then stopping. By means of the real-time exhaust volume flow rate and the target constant, the real-time nitrogen concentration in the hydrogen circulation path can be determined more simply and accurately, and the dependence on the control unit can be eliminated.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cell systems, and in particular, to a hydrogen discharge method, device, electronic device, and readable storage medium for a fuel cell system. Background Art

[0002] The application of proton exchange membrane fuel cell technology in automobiles has become increasingly mature, but there are also many problems, such as the hydrogen consumption problem of fuel cell engines.

[0003] In the existing fuel cell system, the hydrogen discharged from the stack is pressurized by a circulation pump or an ejector pump and then injected into the anode inlet of the stack to form a hydrogen circulation path. This method greatly reduces the hydrogen consumption of the fuel cell. However, with the operation of the fuel cell system, in order to reduce the hydrogen emission while discharging impurity gases, it is necessary to control the opening time and frequency of the hydrogen discharge valve accordingly. However, the current hydrogen discharge strategies are all relatively dependent on the controller and have low accuracy. Summary of the Invention

[0004] The purpose of the present invention is to provide a hydrogen discharge method, device, electronic device, and readable storage medium for a fuel cell system, which can more simply and accurately determine the real-time nitrogen concentration in the hydrogen circulation path through the real-time volume flow rate of exhaust gas and a target constant, and get rid of the dependence on the control unit.

[0005] In a first aspect, an embodiment of the present invention provides a hydrogen discharge method for a fuel cell system, the method comprising:

[0006] Determine the exhaust speed and exhaust density according to the volume flow rate of the current exhaust gas of the hydrogen discharge valve in the hydrogen circulation path;

[0007] Determine a target constant according to the exhaust speed and the exhaust density;

[0008] Calculate the real-time nitrogen concentration in the hydrogen circulation path based on the target constant;

[0009] If the real-time nitrogen concentration meets the preset hydrogen discharge requirement, control the hydrogen discharge valve to open, and repeat the step of determining the exhaust speed and exhaust density according to the volume flow rate of the current exhaust gas of the hydrogen discharge valve in the hydrogen circulation path until the real-time nitrogen concentration meets the preset nitrogen concentration threshold and then stop.

[0010] Combined with the first aspect, an embodiment of the present invention provides a first possible implementation manner of the first aspect, wherein the step of determining a target constant according to the exhaust speed and the exhaust density includes:

[0011] Determine a target constant based on the product of the exhaust speed and the square root of the gas density ρ in the exhaust hole of the hydrogen discharge valve.

[0012] In combination with the first aspect, an embodiment of the present invention provides a second possible implementation manner of the first aspect, wherein the exhaust hole of the hydrogen discharge valve is a columnar hole that meets a preset diameter threshold, and the inner wall of the columnar hole is smooth.

[0013] In combination with the first aspect, an embodiment of the present invention provides a third possible implementation manner of the first aspect, wherein the steps of determining the exhaust speed and exhaust density according to the current volume flow rate of the hydrogen discharge valve in the hydrogen circulation path include:

[0014] Determine the volume in the exhaust hole of the hydrogen discharge valve under high pressure according to the volume of the discharged gas measured by the water displacement method under atmospheric pressure;

[0015] Based on the volume of the discharged gas under atmospheric pressure, the molar volume of the gas under standard conditions, and the relative molecular masses of various gases in the discharged gas, determine the mass of the discharged gas;

[0016] According to the mass of the discharged gas and the volume in the exhaust hole of the hydrogen discharge valve under high pressure, determine the exhaust density;

[0017] According to the current volume flow rate of the hydrogen discharge valve and the cross-sectional area of the exhaust hole, determine the exhaust speed.

[0018] In combination with the first aspect, an embodiment of the present invention provides a fourth possible implementation manner of the first aspect, wherein the steps of calculating the real-time nitrogen concentration in the hydrogen circulation path based on the target constant include:

[0019] Based on the target constant, the cross-sectional area of the exhaust hole of the hydrogen discharge valve, the current volume flow rate of the hydrogen discharge valve, and the water vapor concentration, calculate the real-time nitrogen concentration in the hydrogen circulation path.

[0020] In combination with the first aspect, an embodiment of the present invention provides a fifth possible implementation manner of the first aspect, wherein before the steps of determining the exhaust speed and exhaust density according to the current volume flow rate of the hydrogen discharge valve in the hydrogen circulation path, it further includes:

[0021] Control the hydrogen discharge valve to open for a trial exhaust operation according to a preset time, and detect the current volume flow rate of the exhaust.

[0022] In combination with the first aspect, an embodiment of the present invention provides a sixth possible implementation manner of the first aspect, wherein the method further includes:

[0023] If the real-time nitrogen concentration does not meet the preset hydrogen discharge requirement, then execute the steps of controlling the hydrogen discharge valve to open for a trial exhaust operation according to a preset time and detecting the current volume flow rate of the exhaust.

[0024] Second aspect, an embodiment of the present invention further provides a hydrogen discharge device for a fuel cell system, the device comprising:

[0025] A parameter determination module, which determines an exhaust speed and an exhaust density according to the current volume flow rate of the exhaust gas discharged by the hydrogen discharge valve in the hydrogen circulation path;

[0026] A constant determination module, which determines a target constant according to the exhaust speed and the exhaust density;

[0027] A concentration calculation module, which calculates the real-time nitrogen concentration in the hydrogen circulation path based on the target constant;

[0028] A hydrogen discharge control module, if the real-time nitrogen concentration meets a preset hydrogen discharge requirement, controls the hydrogen discharge valve to open, and repeats the step of determining the exhaust speed and the exhaust density according to the current volume flow rate of the exhaust gas discharged by the hydrogen discharge valve in the hydrogen circulation path until the real-time nitrogen concentration meets a preset nitrogen concentration threshold and then stops.

[0029] Third aspect, an embodiment provides an electronic device, comprising a memory and a processor, wherein a computer program executable on the processor is stored in the memory, and when the processor executes the computer program, the steps of the method according to any one of the foregoing embodiments are implemented.

[0030] Fourth aspect, an embodiment provides a machine-readable storage medium, which stores machine-executable instructions, and when the machine-executable instructions are called and executed by a processor, the machine-executable instructions cause the processor to implement the steps of the method according to any one of the foregoing embodiments.

[0031] The embodiments of the present invention bring a hydrogen discharge method, device, electronic device and readable storage medium for a fuel cell system. By determining the target constant based on the volume flow rate of the discharged gas detected after each opening of the hydrogen discharge valve, and calculating the real-time nitrogen concentration in the hydrogen circulation path based on the target constant, a more accurate purging strategy can be realized. At the same time, since this calculation method is relatively simple, it can also reduce the dependence on the computing and storage capabilities of the vehicle-mounted ECU.

[0032] Other features and advantages of the present invention will be described in the following description, and part of them will become obvious from the description, or will be understood by implementing the present invention. The objectives and other advantages of the present invention are achieved and obtained by the structures specifically pointed out in the description and the drawings.

[0033] To make the above objectives, features and advantages of the present invention more obvious and understandable, the following specifically enumerates preferred embodiments and, in conjunction with the accompanying drawings, makes a detailed description as follows. Description of the Drawings

[0034] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0035] Figure 1 Flowchart of a hydrogen discharge method for a fuel cell system provided by an embodiment of the present invention;

[0036] Figure 2 Schematic diagram of the application of a hydrogen discharge valve provided by an embodiment of the present invention;

[0037] Figure 3 Schematic diagram of the structure of a target constant test device provided by an embodiment of the present invention;

[0038] Figure 4 Another flowchart of a hydrogen discharge method for a fuel cell system provided by an embodiment of the present invention;

[0039] Figure 5 Schematic diagram of the functional modules of a hydrogen discharge device for a fuel cell system provided by an embodiment of the present invention;

[0040] Figure 6 Schematic diagram of the hardware architecture of an electronic device provided by an embodiment of the present invention. Specific embodiments

[0041] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions of the present invention with reference to the drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0042] Currently, a fuel cell system mainly consists of three modules: a hydrogen path subsystem, an air path subsystem, and a cooling subsystem. The hydrogen path subsystem is responsible for providing fuel - hydrogen for the fuel cell system. The hydrogen in the hydrogen storage tank reaches the proportional valve and hydrogen injection valve in the fuel cell system through a high-pressure pipeline. These two valves control the hydrogen pressure entering the fuel cell system. After the pressure adjustment by the above two valves, hydrogen enters the anode inlet of the fuel cell stack, and at this time, the stack can operate. However, the hydrogen is not completely consumed by the stack, and the remaining hydrogen will be discharged from the anode outlet of the stack. Due to its flammable and explosive properties, if this part of hydrogen is directly discharged to the external environment, it will not only cause waste of energy but also be unsafe.

[0043] To solve this problem, in the existing fuel cell system, the hydrogen discharged from the stack is pressurized by a circulation pump or an ejector pump and then injected into the anode inlet of the stack, thus forming a hydrogen circulation path. This method greatly reduces the hydrogen consumption of the fuel cell.

[0044] However, in the actual application process, when the fuel cell system is operating, air is supplied to the cathode of the stack. The oxygen in the air will be consumed by the stack, and at the same time, a part of the remaining nitrogen in the air will permeate from the proton exchange membrane to the anode. The amount of nitrogen in the anode will increase over time, and the increase in nitrogen will reduce the hydrogen concentration. When the hydrogen concentration is reduced to a certain extent, it will seriously affect the power generation performance of the fuel cell stack. Therefore, a hydrogen discharge valve needs to be added in the hydrogen circulation path to regularly discharge impurity gases and the by-product water generated by the fuel cell power generation.

[0045] The hydrogen discharge valve can adopt a solenoid valve with an accurately controllable switching time and fast response. It does not have the function of selective exhaust. Therefore, when the hydrogen discharge valve is opened, all the anode gases composed of hydrogen, nitrogen, water vapor, etc. are discharged. After research by the inventor, it is found that excessive hydrogen discharge will still increase the hydrogen consumption of the fuel cell system. In order to be able to discharge impurity gases while reducing hydrogen emissions, it is necessary to control the opening time and frequency of the hydrogen discharge valve accordingly. For example, estimating the nitrogen concentration in the hydrogen circulation path and reasonably controlling the opening time and frequency of the hydrogen discharge valve according to the nitrogen concentration will form various control strategies for the hydrogen discharge valve, that is, the hydrogen discharge strategy, or the anode purge strategy (purge strategy).

[0046] The existing mainstream hydrogen discharge strategies mainly have two types: the ampere-hour method and the method of estimating the nitrogen concentration first and then discharging hydrogen. Both of these two hydrogen discharge strategies have certain requirements for the computing power and data storage capacity of the vehicle-mounted electronic control unit ECU.

[0047] Here, the ampere-hour method is also called the equivalent Q value method (EQV). The specific approach is to integrate the output current i of the fuel cell with respect to time t, and then multiply this integral value by a weighting coefficient w. When the product of the integral value and the weighting coefficient increases to a fixed value Q, hydrogen discharge starts. The calculation method is as follows:

[0048] Q = ∫w×idt

[0049] Among them, the values of Q and w are different under different operating conditions of the fuel cell system.

[0050] However, the above method has the following drawbacks: The ampere-hour hydrogen evacuation strategy requires the vehicle-mounted ECU to perform real-time integral calculation and storage. It roughly determines whether hydrogen evacuation is needed based on time and current. Therefore, the ampere-hour method is highly dependent on the calculation and storage capabilities of the ECU. Additionally, this method does not evacuate hydrogen based on the nitrogen concentration in the hydrogen circulation path. Moreover, in different operating conditions of the fuel cell system, the nitrogen concentration in the hydrogen circulation path varies greatly. So, this method estimates the nitrogen concentration very inaccurately.

[0051] In addition, the strategy of estimating the nitrogen concentration for hydrogen evacuation is divided into two steps. First, based on Fick's diffusion law, the nitrogen permeability of the proton exchange membrane used in the fuel cell system is calibrated in previous experiments, and then a mathematical model of the anode nitrogen concentration increasing with time is simulated. Second, the hydrogen evacuation rate of the hydrogen evacuation valve is calibrated through previous experiments. Then, the vehicle-mounted ECU calculates the nitrogen concentration in the hydrogen circulation path in real time according to the mathematical model of the nitrogen concentration increase. When the nitrogen concentration increases to the set value, hydrogen evacuation is performed according to the exhaust rate of the hydrogen evacuation valve.

[0052] This method estimates the nitrogen concentration for hydrogen evacuation, which requires pre-calibrating the nitrogen permeability of the corresponding proton exchange membrane in the laboratory according to Fick's law to obtain a model of the nitrogen concentration increasing with time. This determines its inherent defect: it is far from the working site. That is to say, when the fuel cell stack is actually operating, the nitrogen concentration in the hydrogen circulation path is calculated according to the mathematical model, rather than the real-time measured nitrogen concentration. If the working environment of the fuel cell system is relatively harsh, this calculation is likely to deviate from the actual nitrogen concentration value. At the same time, this model needs to be calculated in real time on the vehicle-mounted ECU to obtain the real-time nitrogen concentration. Therefore, this strategy also has a considerable dependence on the calculation and storage capabilities of the ECU.

[0053] Based on this, an embodiment of the present invention provides a hydrogen evacuation method, device, electronic device, and readable storage medium for a fuel cell system, which alleviates the problems in the prior art that the real-time nitrogen concentration in the hydrogen circulation path cannot be obtained, resulting in poor hydrogen evacuation control accuracy and high dependence on the controller.

[0054] To facilitate the understanding of this embodiment, first, a hydrogen evacuation method for a fuel cell system disclosed in an embodiment of the present invention will be introduced in detail.

[0055] Figure 1 It is a schematic flow diagram of a hydrogen evacuation method for a fuel cell system provided by an embodiment of the present invention.

[0056] Referring to Figure 1 This method can be used in an electronic control unit (ECU) and can be implemented through the following steps:

[0057] Step S102: Determine the exhaust speed and exhaust density according to the current volume flow rate of the hydrogen exhaust valve in the hydrogen circulation path.

[0058] As known from the foregoing embodiments, the hydrogen circulation path is provided in the fuel cell system. By detecting the volume flow rate of the gas currently discharged by the hydrogen exhaust valve, the speed and density of the gas discharged from the hydrogen exhaust valve can be determined.

[0059] Step S104: Determine the target constant according to the exhaust speed and exhaust density.

[0060] It should be noted that the inventors have found through research that a fixed constant can be calculated based on the exhaust speed and exhaust density, and the exhaust conditions of the hydrogen exhaust valve under various pressure, humidity and other conditions correspond to this target constant.

[0061] Step S106: Calculate the real-time nitrogen concentration in the hydrogen circulation path based on the target constant.

[0062] In the embodiments of the present invention, the real-time nitrogen concentration in the hydrogen circulation path can be obtained more accurately and conveniently through this target constant.

[0063] Step S108: If the real-time nitrogen concentration meets the preset hydrogen exhaust requirement, control the hydrogen exhaust valve to open, and repeat Step S102 until the real-time nitrogen concentration meets the preset nitrogen concentration threshold and then stop.

[0064] It can be understood that according to the relatively accurate real-time nitrogen concentration in the hydrogen circulation path, the opening of the hydrogen exhaust valve is accurately controlled to achieve single exhaust, and S102 - S108 are cycled until the nitrogen concentration in the hydrogen circulation path meets the preset conditions, that is, the gas concentration after the impurity gas in the hydrogen circulation path is exhausted can meet the application requirements.

[0065] In the embodiments of the present invention, the target constant is determined by detecting the volume flow rate of the discharged gas after each opening of the hydrogen exhaust valve, and the real-time nitrogen concentration in the hydrogen circulation path is calculated based on this target constant, which can achieve a more accurate purging strategy. At the same time, because this calculation method is relatively simple, it can also reduce the dependence on the calculation and storage capabilities of the vehicle-mounted ECU.

[0066] In some embodiments, the inventors have found through research that a fixed target constant can be obtained based on the exhaust parameters. Step S104 may include: determining the target constant based on the product of the exhaust speed and the square root of the gas density ρ in the exhaust hole of the hydrogen exhaust valve.

[0067] It should be noted that since the molecular weight of nitrogen is 28 and the molecular weight of hydrogen is 2, nitrogen molecules are heavier and hydrogen molecules are lighter. The pressure in the hydrogen circulation path during hydrogen discharge is constant for a short period of time. That is to say, the force "prompting the gas molecules to be discharged" for the discharged gas is constant. With different hydrogen-nitrogen ratios, the density of the mixed gas will be different. According to Newton's second law, the acceleration generated by the mixed gas under this force will be different, and thus the volume of the discharged gas within the same hydrogen discharge time will be different. Therefore, the hydrogen discharge valve can be tried to discharge once, and then based on this gas volume, the nitrogen concentration in the anode circulation path of the mixed gas can be judged, and according to this exhaust rate, it can be calculated how long the hydrogen discharge valve needs to work to completely remove the nitrogen.

[0068] Exemplarily, Figure 2 As shown, the hydrogen discharge valve used in the fuel cell system has a cylindrical exhaust hole with a diameter of 2 mm and a length of 10 mm, and the inner wall of the exhaust hole is smooth. The hydrogen-nitrogen mixed gas is discharged under the action of the pressure P in the hydrogen circulation path. Since the inner wall of the exhaust hole is smooth and the exhaust time is extremely short, the exhaust resistance can be ignored. Due to the relatively large exhaust pressure but the very light gas molecules, it can be considered that the exhaust speed reaches a very high value within an extremely short period of time. The resistance at the outlet of the exhaust hole has a compression effect on the gas in the exhaust hole, and it can be considered that during exhaust, the density of the mixed gas in the exhaust hole remains unchanged, and the flow of the gas in the exhaust hole satisfies the conditions of steady flow. Therefore, the Bernoulli equation can be used to estimate this exhaust process.

[0069]

[0070] For gases, gravity can be ignored, and the Bernoulli equation becomes:

[0071]

[0072] where P is the pressure, ρ is the gas density, v is the exhaust speed, and E is a constant representing a certain value of energy; from equation ①, it can be transformed to get:

[0073]

[0074] Let: Continue to transform to get:

[0075]

[0076] This formula indicates that the exhaust speed v is inversely proportional to the square root of the density ρ of the exhaust gas, that is, when other exhaust conditions remain unchanged, the product of the exhaust speed v and the square root of the density ρ of the gas in the exhaust hole is a constant K (the target constant).

[0077] Among them, the exhaust hole of the hydrogen discharge valve adopted in the embodiment of the present invention is a columnar hole that meets a preset diameter threshold, and the inner wall of the columnar hole is smooth to meet the condition that the exhaust resistance can be ignored. When discharging hydrogen, a steady flow can be formed in the exhaust hole. In other words, the prerequisite for the exhaust strategy in the embodiment of the present invention to be realized is that the exhaust hole of the hydrogen discharge valve is a columnar hole with a diameter small enough (meeting the preset diameter threshold) and a smooth inner wall.

[0078] It should be noted that Figure 3 As shown, the fuel cell test bench can provide hydrogen-nitrogen mixed gas with different ratios and precisely control the temperature, pressure, humidity, etc. of the mixed gas. PC is a pressure sensor, and TC is a temperature sensor. The mass spectrometer is used to monitor the concentrations of hydrogen and nitrogen in the gas source in real time. The test sample is the hydrogen discharge valve used on the fuel cell system of our company. The gas discharged from the hydrogen discharge valve is collected by the water displacement method and the volume is measured.

[0079] Among them, the exhaust volumes of wet gas with a humidity of 100% and dry gas with a humidity of 0% at different exhaust pressures and temperatures are respectively tested through this test bench, and the opening time t of the hydrogen discharge valve each time is 0.5 s. After a week of repeated experiments, the measured experimental data are shown in Table 1:

[0080] Table 1:

[0081]

[0082]

[0083] It should be noted that: when the hydrogen discharge valve discharges wet gas with a humidity of 100%, due to the work done by the gas pressure, the internal energy of the gas is lost and the temperature drops. In addition, the water in the water displacement method pool has a lower temperature, so the water vapor in the wet gas will condense. The higher the temperature, the greater the saturated vapor pressure and the more water vapor that condenses. Therefore, the higher the temperature, the smaller the measured exhaust volume of the wet gas. The exhaust volume of dry gas with a humidity of 0% seems to be little affected by temperature.

[0084] In some embodiments, through the detected exhaust volume flow rate, other parameters of the exhaust can be determined, which is convenient for subsequent calculations and can also verify the target constants corresponding to the above various conditions. The foregoing step S102 includes:

[0085] Step 1.1), determine the volume in the exhaust hole of the hydrogen discharge valve under high pressure according to the volume of the gas discharged under atmospheric pressure measured by the water displacement method.

[0086] Here, since the volume measured by the water displacement method is the exhaust volume under atmospheric pressure, it needs to be converted into the volume in the exhaust hole under high pressure. Generally, the high pressure is 10 MPa ≤ p < 100 MPa:

[0087]

[0088] Among them, P1 is the standard atmospheric pressure, which can be taken as 101 kPa, V1 is the volume measured by the water displacement method, P2 is the exhaust pressure, and V2 is the gas volume at the exhaust pressure.

[0089] It should be noted that when testing wet gas, V1 in Equation ③ should be replaced by the total volume of the volume measured by the water displacement method and the volume of condensed water vapor:

[0090] In step 1.2), based on the volume of the gas discharged under atmospheric pressure, the molar volume of the gas at standard conditions, and the relative molecular mass of each type of gas in the discharged gas, determine the mass of the discharged gas.

[0091] Here, the formula for calculating the total exhaust mass is:

[0092]

[0093] Among them, m is the mass of the discharged gas, CN is the nitrogen concentration in the mixed gas, CH is the hydrogen concentration in the mixed gas, CH2O is the water vapor concentration in the mixed gas. When the humidity is 100%, CH2O = saturated vapor pressure / P2, and the saturated vapor pressure can be found in relevant materials and can be known by those skilled in the art; when the humidity is 0%, CH2O = 0, and the molar volume of the gas at standard conditions is 22.4.

[0094] In step 1.3), according to the mass of the discharged gas and the volume inside the exhaust hole of the hydrogen discharge valve under high pressure, determine the exhaust density.

[0095] Among them, the formula for calculating the exhaust density ρ is:

[0096]

[0097] Substitute the aforementioned exhaust gas volume and exhaust mass formulas to obtain the density calculation formula:

[0098]

[0099] In step 1.4), according to the current volume flow rate of the hydrogen discharge valve and the cross-sectional area of the exhaust hole, determine the exhaust speed.

[0100] Exemplarily, if the inner diameter of the hydrogen discharge valve used in this experiment or the embodiment of the present invention is d = 2 mm, then the cross-sectional area A of the hydrogen discharge hole = 1 / 4 × 3.1415926 × d2, and the exhaust time t = 0.5 s. The formula for calculating the exhaust speed v is:

[0101]

[0102] Among them, f is the volume flow rate of the hydrogen discharge valve, unit: L / s.

[0103] It is understandable that the exhaust gas volume, exhaust gas density, and exhaust gas velocity calculated by the inventor through the foregoing steps are used to verify the target constant K value, and the verification results are shown in Table 2.

[0104] Table 2:

[0105]

[0106]

[0107] It can be clearly seen from Table 2 that when the pressure, temperature, and humidity are the same, the K values of the mixed gases with different hydrogen-nitrogen ratios are approximately equal, that is, a fixed target constant can be obtained based on the exhaust parameters of the mixed gases with different hydrogen-nitrogen ratios. For example, when the pressure is 155 kPa, the temperature is 30 °C, and the humidity is 100%, for 8 groups of mixed gases with different hydrogen-nitrogen ratios, K = 320 ± 10. Another example: when the pressure is 245 kPa, the temperature is 70 °C, and the humidity is 0%, for 8 groups of mixed gases with different hydrogen-nitrogen ratios, K = 720 ± 20. Among them, the above errors may be composed of the reading error of measuring the volume by the water displacement method, the human operation error, the environmental error, the mass spectrometer measurement error, etc.

[0108] After the above target constant K value law is successfully verified, the user can directly calculate the corresponding exhaust parameters according to the steps S102 of the above embodiment, and calculate the corresponding target constant under the current conditions based on step S104, and estimate the nitrogen concentration in the hydrogen circulation path through the K value law, so as to make subsequent calculations more convenient.

[0109] In some embodiments, the purpose of more simply measuring the real-time nitrogen concentration in the hydrogen circulation path can be achieved through the target constant, so as to get rid of the dependence on the vehicle ECU. The foregoing step S106 may include:

[0110] Step 2.1), based on the target constant, the cross-sectional area of the exhaust hole of the hydrogen discharge valve, the current exhaust volume flow rate of the hydrogen discharge valve, and the water vapor concentration, calculate the real-time nitrogen concentration in the hydrogen circulation path.

[0111] Among them, the K value of the hydrogen discharge valve used in the fuel cell system can be pre-calibrated: divide the experiments into n groups according to the pressure, temperature, and humidity, calibrate the K values of the hydrogen discharge valve under different pressures, temperatures, and humidities, and store the database composed of this series of K values in the vehicle-mounted ECU. The specific process is as described in the foregoing embodiment.

[0112] The nitrogen concentration calculation formula is as follows: By combining the above formulas ②⑤⑥, we get:

[0113]

[0114] Wherein, CN is the estimated nitrogen concentration in the hydrogen circulation path, P1 is the atmospheric pressure in the laboratory during calibration, K is the product of the square root of the exhaust gas density and the exhaust gas velocity, A is the cross-sectional area of the exhaust hole of the hydrogen discharge valve, f is the volume flow rate of the hydrogen discharge valve under standard conditions, P2 is the exhaust pressure, and CH2O is the water vapor concentration, the value of which is the ratio of the saturated vapor pressure at the exhaust temperature to the exhaust pressure.

[0115] In some embodiments, before step S102, it further includes:

[0116] Step 3.1), control the opening of the hydrogen discharge valve according to a preset time for a trial discharge operation, and detect the current volume flow rate of the exhaust gas.

[0117] As an optional embodiment, a volume flow meter can be installed behind the hydrogen discharge valve. When the fuel cell system is working, every once in a while Δt (Δt can be set according to empirical values), that is, when reaching the preset time point, a trial discharge is performed once. The trial discharge time should be as short as possible to avoid increasing hydrogen consumption. Then measure the trial discharge flow rate f, and then calculate the nitrogen concentration according to the flow rate f, the K value, the exhaust pressure P2, the cross-sectional area A, etc. Then judge whether the hydrogen discharge requirement is met; if the current nitrogen concentration does not meet the preset hydrogen discharge requirement, no hydrogen discharge is performed, and wait for Δt for the next trial discharge, that is, execute step 3.1); when the nitrogen concentration meets the hydrogen discharge requirement, start to open the hydrogen discharge valve once for hydrogen discharge according to a certain exhaust time ΔT. Each time hydrogen is discharged, the current volume flow rate f of the exhaust gas should be measured, and step S102 should be repeatedly executed to calculate the nitrogen concentration, and then a single hydrogen discharge is performed.

[0118] Repeat the above steps until the nitrogen concentration drops to a reasonable range, end the hydrogen discharge, and wait for Δt for the next trial discharge.

[0119] In some embodiments, the single hydrogen discharge time ΔT is determined according to the volume of the hydrogen circulation path cavity and the current exhaust rate of the hydrogen discharge valve:

[0120]

[0121] Wherein, V AN is the volume of the fuel cell anode circulation path cavity, σ is a coefficient less than 1, the purpose is to control the single hydrogen discharge time, which is determined according to the actual hydrogen consumption of the fuel cell system, and f is the flow rate during the single hydrogen discharge when the hydrogen discharge valve was opened last time.

[0122] As Figure 4 shown, the embodiment of the present invention also provides another hydrogen discharge method for a fuel cell system, which further includes the following steps:

[0123] When the vehicle encounters an emergency, in step S201, the vehicle-mounted ECU sends an emergency hydrogen discharge instruction; in step S202, the hydrogen discharge valve receives the instruction to perform hydrogen discharge.

[0124] Step S211: The in-vehicle ECU sends a hydrogen discharge instruction according to the lowest voltage of the stack CVM; Step S212: The hydrogen discharge valve accepts the instruction and discharges hydrogen.

[0125] Step S221: The in-vehicle ECU periodically sends a trial discharge command; Step S222: The single-chip microcomputer of the hydrogen discharge valve receives the instruction and controls the hydrogen discharge valve to discharge hydrogen; Step S223: The rotameter measures the hydrogen discharge flow rate and uploads it to the single-chip microcomputer of the hydrogen discharge valve; Step S224: The single-chip microcomputer of the hydrogen discharge valve calculates the nitrogen concentration based on the target constant, where the single-chip microcomputer obtains it by retrieving from the K value database according to the temperature and pressure;

[0126] Step S225: Determine whether the hydrogen discharge requirement is met. If not, execute Step S221;

[0127] If it is met, execute Step S226. The single-chip microcomputer of the hydrogen discharge valve controls the hydrogen discharge. Among them, the hydrogen discharge time is determined according to the volume of the hydrogen circulation path cavity and the current exhaust rate of the hydrogen discharge valve;

[0128] Step S227: The hydrogen discharge valve discharges hydrogen. At the same time, the flowmeter measures the exhaust flow rate of this time and jumps to Step S224.

[0129] In the real-time nitrogen concentration calculation in the embodiment of the present invention, it does not depend on the real-time calculation of the in-vehicle ECU, and the calculation amount is very small. A simple single-chip microcomputer can be integrated with the hydrogen discharge valve. The in-vehicle ECU only needs to perform simple enabling or authorization control. During the hydrogen discharge process, each hydrogen discharge controls the opening time ΔT of the hydrogen discharge valve according to the real-time nitrogen concentration, so the hydrogen discharge is more accurate and effective, and the hydrogen consumption is more saved.

[0130] As Figure 5 shown, the embodiment of the present invention provides a hydrogen discharge device for a fuel cell system. The device includes:

[0131] A parameter determination module that determines the exhaust speed and exhaust density according to the current exhaust volume flow rate of the hydrogen discharge valve in the hydrogen circulation path;

[0132] A constant determination module that determines the target constant according to the exhaust speed and the exhaust density;

[0133] A concentration calculation module that calculates the real-time nitrogen concentration in the hydrogen circulation path based on the target constant;

[0134] A hydrogen discharge control module. If the real-time nitrogen concentration meets the preset hydrogen discharge requirement, it controls the hydrogen discharge valve to open and repeats the step of determining the exhaust speed and exhaust density according to the current exhaust volume flow rate of the hydrogen discharge valve in the hydrogen circulation path until the real-time nitrogen concentration meets the preset nitrogen concentration threshold and then stops.

[0135] In the embodiments of the present invention, the calculated amount of hydrogen discharge is significantly reduced, reducing the dependence of hydrogen discharge control on the vehicle-mounted ECU. If the strategy calculation and control are integrated on the flow meter or hydrogen discharge valve using a simple processor separately, the vehicle-mounted ECU only needs to perform simple enabling or authorization control. Each hydrogen discharge is carried out by controlling the opening time of the hydrogen discharge valve according to the real-time nitrogen concentration. Therefore, the calculation of the nitrogen concentration in the embodiments of the present invention is more accurate.

[0136] The embodiments of the present invention provide an electronic device for implementation. In this embodiment, the electronic device may be, but is not limited to, a computer device with analysis and processing capabilities such as a personal computer (PC), a laptop computer, a monitoring device, a server, etc.

[0137] As an exemplary embodiment, refer to Figure 6 , the electronic device 110 includes a communication interface 111, a processor 112, a memory 113, and a bus 114. The processor 112, the communication interface 111, and the memory 113 are connected through the bus 114; the above-mentioned memory 113 is used to store a computer program that supports the processor 112 to execute the above-mentioned image sharpening method, and the above-mentioned processor 112 is configured to execute the program stored in the memory 113.

[0138] The machine-readable storage medium mentioned in this article can be any electronic, magnetic, optical, or other physical storage device that can contain or store information such as executable instructions, data, etc. For example, the machine-readable storage medium can be: RAM (Radom Access Memory, random access memory), volatile memory, non-volatile memory, flash memory, storage drives (such as hard disk drives), any type of storage disk (such as optical discs, DVDs, etc.), or similar storage media, or a combination thereof.

[0139] The non-volatile medium can be non-volatile memory, flash memory, storage drives (such as hard disk drives), any type of storage disk (such as optical discs, DVDs, etc.), or similar non-volatile storage media, or a combination thereof.

[0140] It can be understood that the specific operation methods of the functional modules in this embodiment can refer to the detailed descriptions of the corresponding steps in the above method embodiments, and will not be repeated here.

[0141] The computer-readable storage medium provided by the embodiments of the present invention stores a computer program in the readable storage medium, and when the computer program code is executed, it can implement the method described in any of the above embodiments. For the specific implementation, refer to the method embodiments and will not be elaborated here.

[0142] Those skilled in the art can clearly understand that for the convenience and conciseness of description, the specific working processes of the systems and devices described above can refer to the corresponding processes in the foregoing method embodiments, and will not be described herein again.

[0143] In addition, in the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" shall be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0144] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0145] Finally, it should be noted that the above-described embodiments are only specific embodiments of the present invention, used to illustrate the technical solutions of the present invention, rather than limiting it. The protection scope of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: any person skilled in the art within the technical scope disclosed by the present invention can still modify the technical solutions recorded in the foregoing embodiments, or can easily think of changes, or make equivalent replacements for some of the technical features; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered by the protection scope of the present invention.

Claims

1. A method for discharging hydrogen in a fuel cell system, characterized in that, The method includes: Determining an exhaust speed and an exhaust density based on the current volume flow rate of hydrogen discharged by the hydrogen discharge valve in the hydrogen circulation path; Determining a target constant based on the exhaust speed and the exhaust density; wherein, the target constant is determined based on the product of the exhaust speed and the square root of the gas density in the exhaust hole of the hydrogen discharge valve; Calculating the real-time nitrogen concentration in the hydrogen circulation path based on the target constant; If the real-time nitrogen concentration meets the preset hydrogen discharge requirement, controlling the hydrogen discharge valve to open, and repeating the step of determining the exhaust speed and the exhaust density based on the current volume flow rate of hydrogen discharged by the hydrogen discharge valve in the hydrogen circulation path until the real-time nitrogen concentration meets the preset nitrogen concentration threshold and then stopping.

2. The method according to claim 1, characterized in that The exhaust hole of the hydrogen discharge valve is a columnar hole that meets a preset diameter threshold, and the inner wall of the columnar hole is smooth.

3. The method according to claim 1, characterized in that, The step of determining the exhaust speed and the exhaust density based on the current volume flow rate of hydrogen discharged by the hydrogen discharge valve in the hydrogen circulation path includes: Determining the volume in the exhaust hole of the hydrogen discharge valve under high pressure based on the volume of the discharged gas measured by the water displacement method at atmospheric pressure; Determining the mass of the discharged gas based on the volume of the discharged gas at atmospheric pressure, the molar volume of the gas under standard conditions, and the relative molecular masses of various gases in the discharged gas; Determining the exhaust density based on the mass of the discharged gas and the volume in the exhaust hole of the hydrogen discharge valve under high pressure; Determining the exhaust speed based on the current volume flow rate of hydrogen discharged by the hydrogen discharge valve and the cross-sectional area of the exhaust hole.

4. The method according to claim 1, wherein The step of calculating the real-time nitrogen concentration in the hydrogen circulation path based on the target constant includes: Calculating the real-time nitrogen concentration in the hydrogen circulation path based on the target constant, the cross-sectional area of the exhaust hole of the hydrogen discharge valve, the current volume flow rate of hydrogen discharged by the hydrogen discharge valve, and the water vapor concentration.

5. The method according to claim 1, wherein Before the step of determining the exhaust speed and the exhaust density based on the current volume flow rate of hydrogen discharged by the hydrogen discharge valve in the hydrogen circulation path, it further includes: Controlling the hydrogen discharge valve to open for a trial discharge operation according to a preset time, and detecting the current volume flow rate of hydrogen discharged.

6. The method according to claim 5, characterized in that, The method further includes: If the real-time nitrogen concentration does not meet the preset hydrogen discharge requirement, performing the step of controlling the hydrogen discharge valve to open for a trial discharge operation according to a preset time and detecting the current volume flow rate of hydrogen discharged.

7. A hydrogen discharge device for a fuel cell system, characterized in that, The device includes: A parameter determination module that determines an exhaust speed and an exhaust density based on the current volume flow rate of hydrogen discharged by the hydrogen discharge valve in the hydrogen circulation path; A constant determination module that determines a target constant based on the exhaust speed and the exhaust density; wherein, the target constant is determined based on the product of the exhaust speed and the square root of the gas density in the exhaust hole of the hydrogen discharge valve; A concentration calculation module that calculates the real-time nitrogen concentration in the hydrogen circulation path based on the target constant; A hydrogen discharge control module that, if the real-time nitrogen concentration meets the preset hydrogen discharge requirement, controls the hydrogen discharge valve to open, and repeats the step of determining the exhaust speed and the exhaust density based on the current volume flow rate of hydrogen discharged by the hydrogen discharge valve in the hydrogen circulation path until the real-time nitrogen concentration meets the preset nitrogen concentration threshold and then stops.

8. An electronic device, characterized in that, It includes a memory, a processor, and a program stored on the memory and capable of running on the processor. When the processor executes the program, the method described in any one of claims 1 to 6 is implemented.

9. A computer-readable storage medium, characterized in that, A computer program is stored in the readable storage medium. When the computer program is executed, the method described in any one of claims 1-6 is implemented.

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