Method for on-line calculation of anode impurity gas concentration of a fuel cell

Abstract

The present application relates to a kind of fuel cell anode impurity gas concentration online calculation method, comprising the following steps: setting the anode impurity gas concentration test system of fuel cell hydrogen path subsystem;When the test system is running, anode impurity gas concentration α is calculated in real time;The anode impurity gas concentration α calculated is compared with the early warning value α max Dynamic contrast, when anode impurity gas concentration α is greater than or equal to early warning value α max Nitrogen valve is opened, impurity gas is discharged, impurity gas concentration is reduced, temperature, humidity and pressure data in the gas flow path of fuel cell hydrogen path subsystem are collected by using relatively mature and low-cost temperature sensor, humidity sensor and pressure sensor, mathematical model is established, anode impurity gas concentration of fuel cell hydrogen path subsystem is accurately calculated and analyzed, and it is compared with the early warning value and safety value of anode impurity gas concentration, the opening and closing of nitrogen valve is accurately controlled, so that the nitrogen discharge strategy of electric pile is more accurate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fuel cells, in particular to a method for on-line calculation of anode impurity gas concentration of a fuel cell. BACKGROUND

[0002] During the hydrogen circulation process of a fuel cell system, nitrogen and water vapor in the cathode air will diffuse to the anode due to the difference in gas component concentration between the cathode and the anode. Therefore, the gas in the anode cavity of the stack is a mixture of hydrogen, water vapor and nitrogen. Long-term operation will result in a decrease in hydrogen partial pressure and increase the possibility of "hydrogen deficiency". Local hydrogen deficiency can promote cathode carbon corrosion under the mechanism of reverse current, and overall hydrogen deficiency can cause anode carbon corrosion and generate negative voltage, resulting in irreversible damage. Therefore, intermittent opening of the drain valve for purging to discharge the nitrogen accumulated in the anode is an important part of the structural design and strategy calibration of the fuel cell system. If the drain valve is opened too frequently or for too long, it will result in waste of hydrogen resources and low system efficiency; if the drain valve is opened too infrequently or for too short a time, the anode will have too many impurities, which can cause a decrease in single-cell voltage and even affect the service life of the stack.

[0003] At present, the monitoring and management of anode hydrogen concentration of a fuel cell system are mainly achieved by model calculation, installation of on-board hydrogen concentration sensors and experimental calibration. Due to the reliability, accuracy and cost of the sensors, the installation of on-board hydrogen concentration sensors is not mature; the model estimation method also has calculation errors, and the hydrogen concentration calculation is "distorted" under extreme conditions. Therefore, it is urgent to propose a method for on-line calculation of anode impurity gas concentration of a fuel cell to simplify and accurately the nitrogen discharge strategy of the system. SUMMARY

[0004] In view of the above, the present application provides a method for on-line calculation of anode impurity gas concentration of a fuel cell, which aims to establish a mathematical model to analyze and calculate the anode impurity gas concentration of the hydrogen subsystem of a fuel cell to simplify and accurately the nitrogen discharge strategy of the system.

[0005] To achieve the above purpose, the present application adopts the following technical solutions:

[0006] A method for on-line calculation of anode impurity gas concentration of a fuel cell, comprising the following steps:

[0007] S1. A test system for the anode impurity gas concentration of a fuel cell hydrogen circuit subsystem is provided. The test system includes a hydrogen source, an ejector, a plate heat exchanger, a fuel cell stack, a water distributor, and a gas flow path. The hydrogen source provides fresh hydrogen to the ejector. After being ejected from the ejector, the hydrogen first passes through the plate heat exchanger and then enters the fuel cell stack. The gas returning from the fuel cell stack first passes through the water distributor and then enters the ejector to mix with the fresh hydrogen. The test system also includes temperature sensors installed at the hydrogen inlet of the newly entering ejector, the water inlet and outlet of the plate heat exchanger, and temperature, pressure, and humidity sensors installed at the gas inlet of the gas returning from the fuel cell stack to the ejector, and at the inlet and outlet of the plate heat exchanger. A flow meter is also installed at the water outlet of the plate heat exchanger. The water distributor is also equipped with a nitrogen purging valve.

[0008] S2. During the operation of the test system, the proportion of impurity gas in the anode mixed gas is calculated in real time, i.e., the anode impurity gas concentration α.

[0009] S3. Set the warning value α for anode impurity gas concentration. max The anode impurity gas concentration α calculated in step S2 is compared with the warning value α. max Dynamic comparison: When the concentration of anode impurity gas α is greater than or equal to the warning value α max When necessary, open the nitrogen venting valve to release impurity gases and reduce their concentration.

[0010] S4. Set the safe value α for the concentration of anode impurity gas. sf Safety value α sf Less than the warning value α max The anode impurity gas concentration α calculated in step S2 is compared with the safety value α. sf Dynamic comparison: When the concentration of impurity gas at the anode, α, is less than the safe value, α... sf When necessary, close the nitrogen venting valve.

[0011] Furthermore, step S2 includes:

[0012] S2-1. Calculate the mass flow rate of hydrogen at each point in the gas flow path;

[0013] The mass flow rate of hydrogen gas newly entering the ejector Calculate using the following formula:

[0014]

[0015] In the formula, Where is the molar mass of hydrogen, N is the number of cells in the fuel cell stack, I is the current generated by the fuel cell, F is the Faraday constant, and β is the hydrogen utilization rate correction parameter, which is usually taken as 1.04.

[0016] The mass flow rate of hydrogen after exiting the plate heat exchanger is equal to the sum of the mass flow rate of hydrogen newly entering the ejector and the mass flow rate of hydrogen flowing back from the stack into the ejector:

[0017]

[0018] The mass flow rate of hydrogen after exiting the plate heat exchanger is equal to the mass flow rate of hydrogen before exiting the ejector into the plate heat exchanger, so there is the following relationship:

[0019]

[0020] Further, the step S2 further comprises:

[0021] S2-2. Calculating the mass flow rate of impurity gas in the gas flow path, i.e. the mass flow rate of nitrogen;

[0022] The mass flow rate of impurity gas in the gas flow path i.e. the mass flow rate of nitrogen, is calculated by the following formula:

[0023]

[0024] wherein a is the anode impurity gas concentration, M is the molar mass of nitrogen, M is the molar mass of hydrogen, and m is the mass flow rate of hydrogen after exiting the plate heat exchanger.

[0025] Further, the step S2 further comprises:

[0026] S2-3. Calculating the mass flow rate of gaseous water and liquid water at various positions in the gas flow path;

[0027] The step S2-3 is specifically divided into the following steps:

[0028] S2-3-1. Calculating the mass fraction of gaseous water at various positions in the gas flow path

[0029] S2-3-2. Calculating the mass flow rate of gaseous water entering the stack

[0030] S2-3-3. Calculating the mass flow rate of gaseous water before exiting the ejector into the plate heat exchanger

[0031] S2-3-4. Calculating the mass flow rate of gaseous water flowing back from the stack into the ejector

[0032] ​S2-3-5. Calculate the mass flow rate of liquid water flowing from the stack into the ejector and the mass flow rate of liquid water before being ejected from the ejector into the plate heat exchanger

[0033] Further, the step S2-3-1 calculates the gaseous water mass fraction at each location in the gas flow path Specifically as follows:

[0034] The gaseous water partial pressure at each location in the gas flow path is calculated according to the following formula:

[0035]

[0036] In the formula, is the gaseous water partial pressure at the location in the gas flow path, RH is the relative humidity of the gas at the location in the gas flow path, and T is the gas temperature at the location in the gas flow path, RH and T are measured by a humidity sensor and a temperature sensor arranged at the location in the gas flow path;

[0037] The gaseous water mass fraction at each location in the gas flow path is calculated according to the following formula:

[0038]

[0039] In the formula, is the gaseous water mass fraction at the location in the gas flow path, is the gaseous water partial pressure at the location in the gas flow path, is the molar mass of water, M is the mixed molar mass of hydrogen and impurities at the location, P is the gas pressure at the location in the gas flow path, and P is measured by a pressure sensor arranged at the location in the gas flow path.

[0040] Further, the step S2-3-2 calculates the mass flow rate of gaseous water into the stack Specifically as follows:

[0041] The mixed gas ejected from the ejector is warmed by the plate heat exchanger, and the liquid water in the mixed gas is all converted into gaseous water, and the mass flow rate of gaseous water into the stack is calculated according to the following formula:

[0042]

[0043] In the formula, m”” is the mass flow rate of hydrogen and impurities in the mixed gas after the plate heat exchanger, is the gaseous water mass fraction after the plate heat exchanger, calculated from formula (5) and formula (6);

[0044] The mass flow rate of hydrogen and impurities in the mixed gas after the plate heat exchanger m'" is equal to the mass flow rate of hydrogen and impurities in the mixed gas before the mixed gas is ejected from the ejector into the plate heat exchanger m'"', thus the following relationship exists:

[0045] m'" = m'" (8);

[0046] The mass flow rate of hydrogen and impurities in the mixed gas before the mixed gas is ejected from the ejector into the plate heat exchanger m'" is equal to the sum of the mass flow rate of hydrogen newly entering the ejector and the mass flow rate of hydrogen flowing back from the stack into the ejector and the mass flow rate of impurity gas in the gas flow path thus the following relationship exists:

[0047]

[0048] The mixed molar mass of hydrogen and impurities in the mixed gas after the plate heat exchanger M'" is calculated by the following formula:

[0049]

[0050] In the formula, a is the concentration of anode impurity gas, M is the molar mass of nitrogen, M is the molar mass of hydrogen.

[0051] Further, the step S2-3-3 calculates the mass flow rate of gaseous water before the mixed gas is ejected from the ejector into the plate heat exchanger Specifically as follows:

[0052] The mass flow rate of gaseous water before the mixed gas is ejected from the ejector into the plate heat exchanger is calculated by the following formula:

[0053]

[0054] In the formula, m'" is the mass flow rate of hydrogen and impurities in the mixed gas before the mixed gas is ejected from the ejector into the plate heat exchanger, is the mass fraction of gaseous water before the mixed gas is ejected from the ejector into the plate heat exchanger, calculated from formula (5) and formula (6);

[0055] The mixed molar mass of hydrogen and impurities in the mixed gas before the mixed gas is ejected from the ejector into the plate heat exchanger M'" is equal to the mixed molar mass of hydrogen and impurities in the mixed gas after the plate heat exchanger M'"', thus the following relationship exists:

[0056] M'" = M'" (12).

[0057] Further, the step S2-3-4 calculates the mass flow rate of gaseous water flowing back from the stack into the ejector In detail:

[0058] The mass flow rate of gaseous water flowing back from the stack into the ejector It is calculated by the following equation:

[0059]

[0060] where m" is the mass flow rate of hydrogen and impurities in the mixed gas flowing back from the stack into the ejector, is the mass fraction of gaseous water flowing back from the stack into the ejector, It is calculated by equation (5) and equation (6);

[0061] The mass flow rate of hydrogen and impurities in the mixed gas flowing back from the stack into the ejector m" and the mass flow rate of hydrogen newly entering the ejector The sum is equal to the mass flow rate of hydrogen and impurities in the mixed gas being ejected from the ejector into the plate heat exchanger before, i.e. there is the following equation:

[0062]

[0063] According to the conservation of mass, there is the following relationship:

[0064]

[0065] where M" is the mixed molar mass of hydrogen and impurities in the mixed gas flowing back from the stack into the ejector. Further, the step S2-3-5 calculates the mass flow rate of liquid water flowing back from the stack into the ejector and the mass flow rate of liquid water before being ejected from the ejector into the plate heat exchanger In detail:

[0066] Due to the conservation of mass of water at each place in the gas flow path, there is the following relationship:

[0067]

[0068] Further, the step S2 further comprises:

[0069] S2-4. Calculating the anode impurity gas concentration a;

[0070] According to the conservation of energy, the sum of the energy of the new hydrogen entering the ejector and the energy of the gas flowing back from the stack into the ejector is equal to the energy of the gas before being ejected from the ejector into the plate heat exchanger:

[0071]

[0072] The sum of the energy of the gas before it is ejected into the plate heat exchanger and the energy provided by the plate heat exchanger to change the liquid water into gaseous water is equal to the energy of the gas after it passes through the plate heat exchanger:

[0073]

[0074] In the formula, Cp is the specific heat capacity of hydrogen, Cpg is the specific heat capacity of gaseous water, Cpl is the specific heat capacity of liquid water, Cpn is the specific heat capacity of nitrogen, T1 is the temperature of the hydrogen that newly enters the ejector, T1 is measured by a first temperature sensor arranged at the hydrogen inlet of the newly entering ejector, T2 is the temperature of the gas that flows back from the stack into the ejector, T2 is measured by a second temperature sensor arranged at the gas inlet of the gas that flows back from the stack into the ejector, T3 is the temperature of the gas before it is ejected into the plate heat exchanger, T3 is measured by a third temperature sensor arranged at the inlet of the plate heat exchanger, T4 is the temperature of the gas after it passes through the plate heat exchanger, T4 is measured by a fourth temperature sensor arranged at the outlet of the plate heat exchanger, T5 is the temperature of the liquid water at the water outlet of the plate heat exchanger, T5 is measured by a fifth temperature sensor arranged at the water outlet of the plate heat exchanger, and T6 is the temperature of the liquid water at the water inlet of the plate heat exchanger, T6 is measured by a sixth temperature sensor arranged at the water inlet of the plate heat exchanger;

[0075] In the formula, m 板 is the mass flow rate of the liquid water of the plate heat exchanger, which is measured by a flow meter arranged at the water outlet of the plate heat exchanger;

[0076] The mass flow rates of the hydrogen at various positions in the gas flow path, the mass flow rates of the gaseous water and the liquid water at various positions, and the mass flow rate of the impurity gas nitrogen calculated in steps S2-1, S2-2 and S2-3 are substituted into formulas (17) and (18) to obtain two equations containing two unknown quantities, and the values of the two unknown quantities are solved to obtain the value of the anode impurity gas concentration a.

[0077] Compared with the prior art, the present application has the following beneficial effects:

[0078] (1) By additionally arranging a nitrogen discharge valve on the water distributor, the water discharge valve is only used to discharge the water in the water distributor, and the nitrogen discharge valve is used to discharge the impurity gas. When the water in the water distributor is discharged to a required degree, the water discharge valve can be closed, thereby greatly shortening the water discharge time. In combination with the calculation of the anode impurity gas concentration, the opening and closing of the nitrogen discharge valve can be accurately controlled, the nitrogen discharge efficiency is improved, and the waste of hydrogen in the fuel cell system can be reduced.

[0079] ​(2) By using more mature and low-cost temperature sensors, humidity sensors and pressure sensors to collect temperature, humidity and pressure data of each place in the gas flow path of the fuel cell hydrogen subsystem, a mathematical model is established to analyze and calculate the anode impurity gas concentration of the fuel cell hydrogen subsystem accurately, and the anode impurity gas concentration is compared with the early warning value and the safety value of the anode impurity gas concentration, so as to accurately control the opening and closing of the nitrogen discharge valve, and make the nitrogen discharge strategy of the stack more accurate.

[0080] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the present application. The objects and other advantages of the present application can be realized and achieved by the structure as indicated in the description and drawings. BRIEF DESCRIPTION OF DRAWINGS

[0081] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0082] Figure 1 The anode impurity gas concentration test system schematic diagram of the fuel cell hydrogen subsystem of the embodiment of the present application is shown;

[0083] In the figure: 1, hydrogen source; 2, ejector; 3, plate heat exchanger; 4, stack; 5, water distributor; 6, nitrogen discharge valve. DETAILED DESCRIPTION

[0084] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0085] The embodiment of the present application proposes an online calculation method for the anode impurity gas concentration of a fuel cell, as shown in the accompanying drawings, which specifically includes the following steps: Figure 1

[0086] ​S1. Set up an anode impurity gas concentration test system of a hydrogen path subsystem of a fuel cell, the test system comprising a hydrogen source 1, an ejector 2, a plate heat exchanger 3, a stack 4, a water segregator 5 and a gas flow path, the hydrogen source 1 providing new hydrogen gas for the ejector 2, the hydrogen gas being sprayed out of the ejector 2 and then passing through the plate heat exchanger 3 before entering the stack 4, the gas flowing back from the stack 4 passing through the water segregator 5 and then entering the ejector 2 to mix with the new hydrogen gas; the test system further comprising temperature sensors arranged at the inlet of the hydrogen gas entering the ejector 2, the inlet and outlet of the plate heat exchanger 3, temperature sensors, pressure sensors and humidity sensors arranged at the inlet and outlet of the plate heat exchanger 3 and the inlet of the gas flowing back from the stack 4 into the ejector 2, and a flow meter arranged at the outlet of the plate heat exchanger 3; the water segregator 5 is further provided with a nitrogen discharge valve 6;

[0087] S2. Calculate the proportion of the amount of substance of the impurity gas in the anode mixed gas, i.e. the anode impurity gas concentration α, in real time when the test system is running;

[0088] S3. Set an anode impurity gas concentration warning value α max , and compare the anode impurity gas concentration α calculated in step S2 with the warning value α max . max When the anode impurity gas concentration α is greater than or equal to the warning value α max , open the nitrogen discharge valve 6 to discharge the impurity gas and reduce the impurity gas concentration.

[0089] Specifically, the anode impurity gas concentration warning value α max may be set to 5% according to experience.

[0090] S4. Set an anode impurity gas concentration safety value α sf , the safety value α sf being less than the warning value α max , and compare the anode impurity gas concentration α calculated in step S2 with the safety value α sf . sf When the anode impurity gas concentration α is less than the safety value α sf , close the nitrogen discharge valve 6.

[0091] Specifically, the anode impurity gas concentration safety value α sf may be set to 1% according to experience.

[0092] Compared with the traditional water separator, the water separator is provided with a nitrogen discharge valve for discharging nitrogen, thereby improving the nitrogen discharge efficiency. The traditional water separator is provided with a water discharge valve, which has a dual function of discharging water and nitrogen. In order to discharge nitrogen, the water discharge time is designed to be long enough to ensure that the water is completely discharged, and then the nitrogen is discharged. Due to the long opening time of the water discharge valve, the hydrogen in the fuel cell system is also discharged, which causes waste of hydrogen. By adding the nitrogen discharge valve to the water separator, the water discharge valve is only used to discharge the water in the water separator, and the nitrogen discharge valve is used to discharge the impurity gas. When the water in the water separator is discharged to a required degree, the water discharge valve is closed, thereby greatly shortening the water discharge time. In combination with the calculation of the anode impurity gas concentration, the opening and closing of the nitrogen discharge valve is accurately controlled, thereby improving the nitrogen discharge efficiency and reducing the waste of hydrogen in the fuel cell system.

[0093] The water is discharged to a required degree, and does not need to be completely discharged. The nitrogen is accurately controlled, thereby saving the hydrogen that runs out together with the nitrogen

[0094] Specifically, in the step S1, a first temperature sensor is arranged at the hydrogen inlet of the ejector 2, a second temperature sensor, a first pressure sensor and a first humidity sensor are arranged at the gas inlet of the ejector 2, a third temperature sensor, a second pressure sensor and a second humidity sensor are arranged at the inlet of the plate heat exchanger 3, a fourth temperature sensor, a third pressure sensor and a third humidity sensor are arranged at the outlet of the plate heat exchanger 3, a fifth temperature sensor and a flow meter are arranged at the water outlet of the plate heat exchanger 3, and a sixth temperature sensor is arranged at the water inlet of the plate heat exchanger 3.

[0095] The specific steps of calculating the anode impurity gas concentration α in real time in the step S2 are as follows:

[0096] S2-1. Calculate the mass flow rate of hydrogen at each position in the gas flow path.

[0097] The mass flow rate of hydrogen newly entering the ejector According to the following formula:

[0098]

[0099] In the formula, is the molar mass of hydrogen, N is the number of single cells of the fuel cell stack, I is the electric current of the fuel cell, F is the Faraday constant, and β is a hydrogen utilization rate correction parameter, which is usually 1.04.

[0100] According to the law of conservation of mass, the mass flow rate of hydrogen before being sprayed into the plate heat exchanger from the ejector is equal to the sum of the mass flow rate of hydrogen newly entering the ejector and the mass flow rate of hydrogen flowing back into the ejector from the fuel cell stack:

[0101]

[0102] wherein, is the mass flow rate of hydrogen gas newly entering the ejector, is the mass flow rate of hydrogen gas flowing back from the stack into the ejector, is the mass flow rate of hydrogen gas before being ejected from the ejector into the plate heat exchanger.

[0103] Since the liquid water in the mixed gas vaporizes into gaseous water after the mixed gas enters the plate heat exchanger, the hydrogen gas does not change, i.e., the mass flow rate of hydrogen gas after exiting the plate heat exchanger is equal to the mass flow rate of hydrogen gas before being ejected from the ejector into the plate heat exchanger Therefore, the following relationship exists:

[0104]

[0105] As can be seen from equation (1), equation (2), and equation (3), the mass flow rate of hydrogen gas newly entering the ejector is directly calculated, the mass flow rate of hydrogen gas before being ejected from the ejector into the plate heat exchanger and the mass flow rate of hydrogen gas after exiting the plate heat exchanger are all expressed as functions of with the mass flow rate of hydrogen gas flowing back from the stack into the ejector as the independent variable.

[0106] S2-2. Calculate the mass flow rate of impurity gas in the gas flow path, i.e., the mass flow rate of nitrogen gas.

[0107] The mass flow rate of impurity gas in the gas flow path i.e., the mass flow rate of nitrogen gas, can be calculated by the following equation:

[0108]

[0109] wherein, a is the anode impurity gas concentration, is the molar mass of nitrogen gas, is the molar mass of hydrogen gas, is the mass flow rate of hydrogen gas after exiting the plate heat exchanger.

[0110] According to the mass flow rate of hydrogen gas after exiting the plate heat exchanger calculated in step S2-1, when substituted into equation (4), the mass flow rate of impurity gas in the gas flow path is expressed as a function of with the mass flow rate of hydrogen gas flowing back from the stack into the ejector as the independent variable and the anode impurity gas concentration a.

[0111] S2-3. Calculate the mass flow rate of gaseous water and liquid water at each location in the gas flow path;

[0112] S2-3-1. Calculate the gaseous water mass fraction at each location in the gas flow path

[0113] The gaseous water partial pressure at each location in the gas flow path is calculated according to the following formula:

[0114]

[0115] In the formula, is the gaseous water partial pressure at the location in the gas flow path, RH is the relative humidity of the gas at the location in the gas flow path, and T is the gas temperature at the location in the gas flow path. RH and T are measured by a humidity sensor and a temperature sensor arranged at the location in the gas flow path.

[0116] The gaseous water mass fraction at each location in the gas flow path is calculated according to the following formula:

[0117]

[0118] In the formula, is the gaseous water mass fraction at the location in the gas flow path, is the gaseous water partial pressure at the location in the gas flow path, is the molar mass of water, M is the mixed molar mass of hydrogen and impurities at the location, P is the gas pressure at the location in the gas flow path, and P is measured by a pressure sensor arranged at the location in the gas flow path.

[0119] S2-3-2. Calculate the mass flow rate of gaseous water entering the stack

[0120] The mixed gas sprayed from the ejector is warmed by the plate heat exchanger, and the liquid water in the mixed gas is vaporized and completely converted into gaseous water. The mass flow rate of gaseous water entering the stack is calculated according to the following formula:

[0121]

[0122] In the formula, m”” is the mass flow rate of hydrogen and impurities in the mixed gas after the plate heat exchanger, is the gaseous water mass fraction after the plate heat exchanger.

[0123] Since the liquid water in the mixed gas is vaporized and becomes gaseous water after the mixed gas enters the plate heat exchanger, the hydrogen and impurity gases do not change, i.e., the mass flow rate of hydrogen and impurities m”” in the mixed gas after the plate heat exchanger is equal to the mass flow rate of hydrogen and impurities m”′ in the mixed gas before entering the plate heat exchanger from the ejector, so there is the following relationship:

[0124] m" = m'" (8);

[0125] From the mass conservation, the mass flow rate of hydrogen and impurities m'" in the mixed gas ejected from the ejector into the plate heat exchanger is equal to the mass flow rate of hydrogen newly entering the ejector and the mass flow rate of hydrogen flowing back from the stack into the ejector and the mass flow rate of impurity gas in the gas flow path Therefore, the following relationship exists:

[0126]

[0127] In the formula, is the mass flow rate of hydrogen newly entering the ejector, is the mass flow rate of hydrogen flowing back from the stack into the ejector, is the mass flow rate of impurity gas in the gas flow path.

[0128] Substituting the mass flow rates calculated in the step S2-1 and the step S2-2 into the formula (9), it can be known that the mass flow rate of hydrogen and impurities m'" in the mixed gas ejected from the ejector into the plate heat exchanger is expressed as a function of and the anode impurity gas concentration a with the mass flow rate of hydrogen flowing back from the stack into the ejector as the independent variable.

[0129] The gaseous water mass fraction after passing through the plate heat exchanger According to the formula (5) and the formula (6), the following is calculated:

[0130]

[0131] In the formula, is the gaseous water partial pressure after passing through the plate heat exchanger, RH3 is the relative humidity of the gas after passing through the plate heat exchanger, and T4 is the gas temperature after passing through the plate heat exchanger. RH3 and T4 are measured by a third humidity sensor and a fourth temperature sensor arranged at the outlet of the plate heat exchanger.

[0132] The gaseous water mass fraction after passing through the plate heat exchanger According to the following formula:

[0133]

[0134] In the formula, is the gaseous water partial pressure after passing through the plate heat exchanger, M is the molar mass of water, M”” is the molar mass of hydrogen and impurities in the mixed gas after passing through the plate heat exchanger, and P3 is the gas pressure of the mixed gas after passing through the plate heat exchanger. P3 is measured by a third pressure sensor located at the outlet of the plate heat exchanger.

[0135] The mixed molar mass M”” of hydrogen and impurities in the gas mixture after passing through the plate heat exchanger is calculated by the following formula:

[0136]

[0137] In the formula, α is the concentration of anode impurity gas. Here is the molar mass of nitrogen. denoted as , where is the molar mass of hydrogen gas.

[0138] From formulas (5-1), (6-1), and (10), it can be seen that the mass fraction of gaseous water after passing through the plate heat exchanger is... It can be expressed as a function of the concentration α of the anode impurity gas.

[0139] In summary, the mass flow rate of gaseous water entering the fuel cell stack can be determined. Expressed as the mass flow rate of hydrogen returning from the fuel cell stack to the ejector, with the independent variable being... It is a function of the concentration of anode impurity gas α.

[0140] S2-3-3. Calculate the mass flow rate of gaseous water before it exits the ejector and enters the plate heat exchanger.

[0141] The mass flow rate of gaseous water ejected from the ejector before entering the plate heat exchanger Calculated using the following formula:

[0142]

[0143] In the formula, m”′ represents the mass flow rate of hydrogen and impurities in the mixed gas before it exits the ejector and enters the plate heat exchanger. The mass fraction of gaseous water before it exits the ejector and enters the plate heat exchanger.

[0144] The mass flow rate m”′ of hydrogen and impurities in the mixed gas before it is ejected from the ejector into the plate heat exchanger is expressed by formula (9).

[0145] The mass fraction of gaseous water ejected from the ejector before entering the plate heat exchanger The results are calculated using formulas (5) and (6), as follows:

[0146]

[0147] In the formula, RH2 is the gaseous water pressure before it exits the ejector and enters the plate heat exchanger, RH3 is the relative humidity of the gas before it exits the ejector and enters the plate heat exchanger, and T3 is the temperature of the gas before it exits the ejector and enters the plate heat exchanger. RH2 and T3 are measured by a second humidity sensor and a third temperature sensor arranged at the gas inlet of the gas exiting the ejector and entering the plate heat exchanger.

[0148]

[0149] In the formula, The pressure of the gaseous water vapor ejected from the ejector before entering the plate heat exchanger. M' is the molar mass of water, M'' is the molar mass of hydrogen and impurities in the mixed gas before it exits the ejector and enters the plate heat exchanger, and P2 is the gas pressure of the mixed gas before it exits the ejector and enters the plate heat exchanger. P2 is measured by a second pressure sensor located at the gas inlet of the gas exiting the ejector and entering the plate heat exchanger.

[0150] Since the liquid water in the mixed gas vaporizes into gaseous water after entering the plate heat exchanger, while the hydrogen and impurity gases remain unchanged, the following relationship exists:

[0151] M”′=M”” (12);

[0152] In the formula, M”′ is the mixed molar mass of hydrogen and impurities in the gas mixture before it enters the plate heat exchanger from the ejector, and M”” is the mixed molar mass of hydrogen and impurities in the gas mixture after it passes through the plate heat exchanger. That is, the mixed molar mass of hydrogen and impurities M”′ in the gas mixture before it enters the plate heat exchanger from the ejector is expressed by formula (10).

[0153] From formulas (5-2), (6-2), (10), and (12), we can see that the mass fraction of gaseous water before it enters the plate heat exchanger from the ejector is... It can be expressed as a function of the concentration α of the anode impurity gas.

[0154] In summary, the mass flow rate of the gaseous water ejected from the ejector before entering the plate heat exchanger can be determined. Expressed as the mass flow rate of hydrogen returning from the fuel cell stack to the ejector, with the independent variable being... It is a function of the concentration of anode impurity gas α.

[0155] S2-3-4. Calculate the mass flow rate of gaseous water flowing back into the ejector from the fuel cell stack.

[0156] Mass flow rate of gaseous water flowing back into the ejector from the fuel cell stack Calculated using the following formula:

[0157]

[0158] In the formula, m” represents the mass flow rate of hydrogen and impurities in the mixed gas flowing back from the fuel cell stack into the ejector. The mass fraction of gaseous water flowing back into the ejector from the fuel cell stack.

[0159] According to the law of conservation of mass, the mass flow rate m” of hydrogen and impurities in the mixed gas flowing back into the ejector from the fuel cell stack is equal to the mass flow rate m” of hydrogen newly entering the ejector. The sum equals the mass flow rate m”′ of hydrogen and impurities in the mixed gas before it exits the ejector and enters the plate heat exchanger, i.e., the following formula exists:

[0160]

[0161] From formulas (1) and (9), it can be seen that the mass flow rate m” of hydrogen and impurities in the mixed gas flowing back into the ejector from the fuel cell stack can be expressed as the mass flow rate of hydrogen flowing back into the ejector from the fuel cell stack, with the independent variable being the mass flow rate of hydrogen. It is a function of the concentration of anode impurity gas α.

[0162] Mass fraction of gaseous water flowing back into the ejector from the fuel cell stack The results are calculated using formulas (5) and (6), as follows:

[0163]

[0164] In the formula, RH1 is the relative humidity of the gas flowing back into the ejector from the fuel cell stack, and T2 is the temperature of the gas flowing back into the ejector from the fuel cell stack. RH1 and T2 are measured by a first humidity sensor and a second temperature sensor arranged at the gas inlet of the gas flowing back into the ejector from the fuel cell stack.

[0165]

[0166] In the formula, The pressure of the gaseous water flowing back from the fuel cell stack to the ejector. M is the molar mass of water, M" is the molar mass of hydrogen and impurities in the mixed gas flowing back into the ejector from the fuel cell stack, and P1 is the gas pressure of the mixed gas flowing back into the ejector from the fuel cell stack. P1 is measured by a first pressure sensor located at the gas inlet of the gas flowing back into the ejector from the fuel cell stack.

[0167] According to the law of conservation of amount of substance:

[0168]

[0169] In the formula, m” is the mass flow rate of hydrogen and impurities in the mixed gas flowing back from the fuel cell stack into the ejector, M” is the mixed molar mass of hydrogen and impurities in the mixed gas flowing back from the fuel cell stack into the ejector, m”′ is the mass flow rate of hydrogen and impurities in the mixed gas before it exits the ejector and enters the plate heat exchanger, and M”′ is the mixed molar mass of hydrogen and impurities in the mixed gas before it exits the ejector and enters the plate heat exchanger. The mass flow rate of the hydrogen gas newly entering the ejector. denoted as , where is the molar mass of hydrogen gas.

[0170] Substituting formulas (1), (9), (10), (12), and (14) into (15), the mixed molar mass M of hydrogen and impurities in the gas returning from the fuel cell stack to the ejector is expressed as the mass flow rate of hydrogen returning from the fuel cell stack to the ejector, with the independent variable being M. It is a function of the concentration of anode impurity gas α.

[0171] From formulas (5-3), (6-3), and (15), it can be seen that the mass fraction of gaseous water flowing back into the ejector from the fuel cell stack is... Expressed as the mass flow rate of hydrogen returning from the fuel cell stack to the ejector, with the independent variable being... It is a function of the concentration of anode impurity gas α.

[0172] In summary, the mass flow rate of gaseous water flowing back from the fuel cell stack into the ejector is... Expressed as the mass flow rate of hydrogen returning from the fuel cell stack to the ejector, with the independent variable being... It is a function of the concentration of anode impurity gas α.

[0173] S2-3-5. Calculate the mass flow rate of liquid water flowing back from the fuel cell stack into the ejector. and the mass flow rate of liquid water before it exits the ejector and enters the plate heat exchanger

[0174] Due to the conservation of water mass at all points in the gas flow path, the following relationship exists:

[0175]

[0176] In the formula, This refers to the mass flow rate of gaseous water entering the fuel cell stack. This refers to the mass flow rate of liquid water ejected from the ejector before entering the plate heat exchanger. The mass flow rate of gaseous water ejected from the ejector before entering the plate heat exchanger. The mass flow rate of liquid water flowing back from the fuel cell stack into the ejector. The mass flow rate of gaseous water flowing back from the fuel cell stack into the ejector.

[0177] Since steps S2-3-2, S2-3-3, and S2-3-4 have already been expressed respectively... and Substituting into formula (16) yields the mass flow rate of the liquid water flowing back from the fuel cell stack into the ejector. and the mass flow rate of liquid water before it exits the ejector and enters the plate heat exchanger Expressed as the mass flow rate of hydrogen gas flowing back into the ejector from the fuel cell stack, respectively. It is a function of the concentration of anode impurity gas α.

[0178] S2-4. Calculate the concentration of anode impurity gas α;

[0179] According to the law of conservation of energy, the sum of the energy of the new hydrogen entering the ejector and the energy of the gas flowing back into the ejector from the fuel cell stack is equal to the energy of the gas ejected from the ejector before entering the plate heat exchanger.

[0180]

[0181] The sum of the energy of the gas ejected from the ejector before entering the plate heat exchanger and the energy provided by the plate heat exchanger in converting liquid water into gaseous water is equal to the energy of the gas after passing through the plate heat exchanger.

[0182]

[0183] In the formula, The specific heat capacity of hydrogen. The specific heat capacity of gaseous water, The specific heat capacity of liquid water, T1 is the temperature of the hydrogen gas newly entering the ejector, measured by the first temperature sensor located at the hydrogen inlet of the ejector; T2 is the temperature of the gas flowing back into the ejector from the fuel cell stack, measured by the second temperature sensor located at the gas inlet of the ejector; T3 is the temperature of the gas ejected from the ejector before entering the plate heat exchanger, measured by the third temperature sensor located at the inlet of the plate heat exchanger; T4 is the temperature of the gas after passing through the plate heat exchanger, measured by the fourth temperature sensor located at the outlet of the plate heat exchanger; T5 is the temperature of the liquid water at the outlet of the plate heat exchanger, measured by the fifth temperature sensor located at the outlet of the plate heat exchanger; and T6 is the temperature of the liquid water at the inlet of the plate heat exchanger, measured by the sixth temperature sensor located at the inlet of the plate heat exchanger.

[0184] In the formula, The mass flow rate of the hydrogen gas newly entering the ejector. This refers to the mass flow rate of hydrogen gas flowing back from the fuel cell stack into the ejector. The mass flow rate of hydrogen gas ejected from the ejector before entering the plate heat exchanger. This is the mass flow rate of hydrogen after exiting the plate heat exchanger.

[0185] In the formula, The mass flow rate of gaseous water flowing back from the fuel cell stack into the ejector. The mass flow rate of liquid water flowing back from the fuel cell stack into the ejector. The mass flow rate of gaseous water ejected from the ejector before entering the plate heat exchanger. This refers to the mass flow rate of liquid water ejected from the ejector before entering the plate heat exchanger. The mass flow rate of gaseous water entering the fuel cell stack;

[0186] In the formula, Let m be the mass flow rate of nitrogen in the gas mixture. 板 The mass flow rate of liquid water in the plate heat exchanger is measured by a flow meter located at the outlet of the plate heat exchanger.

[0187] Substituting the mass flow rates of hydrogen, gaseous water, and liquid water at various points in the gas flow path calculated in steps S2-1, S2-2, and S2-3, as well as the mass flow rate of the impurity gas nitrogen, into formulas (17) and (18), we obtain two linear equations in two variables. The two unknowns are the mass flow rates of hydrogen flowing back from the fuel cell stack to the ejector. By solving the two equations for the anode impurity gas concentration α and the two unknowns, the value of the anode impurity gas concentration α can be calculated.

[0188] By using relatively mature and low-cost temperature, humidity, and pressure sensors to collect temperature, humidity, and pressure data at various points in the gas flow path of the fuel cell hydrogen circuit subsystem, a mathematical model is established to analyze and calculate the anode impurity gas concentration of the fuel cell hydrogen circuit subsystem accurately. This concentration is then compared with the warning and safety values ​​for the anode impurity gas concentration to precisely control the opening and closing of the nitrogen purging valve, making the stack nitrogen purging strategy more precise.

[0189] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for online calculation of impurity gas concentration at the anode of a fuel cell, characterized in that, Includes the following steps: S1. A test system for the anode impurity gas concentration of a fuel cell hydrogen circuit subsystem is provided. The test system includes a hydrogen source, an ejector, a plate heat exchanger, a fuel cell stack, a water distributor, and a gas flow path. The hydrogen source provides fresh hydrogen to the ejector. After being ejected from the ejector, the hydrogen first passes through the plate heat exchanger and then enters the fuel cell stack. The gas returning from the fuel cell stack first passes through the water distributor and then enters the ejector to mix with the fresh hydrogen. The test system also includes temperature sensors installed at the hydrogen inlet of the newly entering ejector, the water inlet and outlet of the plate heat exchanger, and temperature, pressure, and humidity sensors installed at the gas inlet of the gas returning from the fuel cell stack to the ejector, and the inlet and outlet of the plate heat exchanger. A flow meter is also installed at the water outlet of the plate heat exchanger. The water distributor is also equipped with a nitrogen purging valve. S2. During the operation of the test system, the proportion of impurity gas in the anode mixed gas is calculated in real time, i.e., the anode impurity gas concentration α. S2-1. Calculate the mass flow rate of hydrogen at each point in the gas flow path; S2-2. Calculate the mass flow rate of the impurity gas in the gas flow path, i.e., the mass flow rate of nitrogen. ; （1）； Here is the molar mass of nitrogen. Here is the molar mass of hydrogen. This is the mass flow rate of hydrogen after exiting the plate heat exchanger. S2-3. Calculate the mass flow rate of gaseous and liquid water at various points in the gas flow path; S2-4. Calculate the concentration of anode impurity gas α; The sum of the energy of the new hydrogen entering the ejector and the energy of the gas flowing back into the ejector from the fuel cell stack is equal to the energy of the gas ejected from the ejector before entering the plate heat exchanger. The sum of the energy of the gas ejected from the ejector before entering the plate heat exchanger and the energy provided by the plate heat exchanger in turning liquid water into gaseous water is equal to the energy of the gas after passing through the plate heat exchanger. We obtain two equations containing two unknowns, the two unknowns being... And α, solve for the value of α; The mass flow rate of hydrogen gas flowing back into the ejector from the fuel cell stack; S3. Set the warning value α for anode impurity gas concentration. max The anode impurity gas concentration α calculated in step S2 is compared with the warning value α. max Dynamic comparison: When the concentration of anode impurity gas α is greater than or equal to the warning value α max When necessary, open the nitrogen venting valve to release impurity gases and reduce their concentration. S4. Set the safe value α for the concentration of anode impurity gas. sf Safety value α sf Less than the warning value α max The anode impurity gas concentration α calculated in step S2 is compared with the safety value α. sf Dynamic comparison: When the concentration of impurity gas at the anode, α, is less than the safe value, α... sf When necessary, close the nitrogen venting valve.

2. The method for online calculation of anode impurity gas concentration in a fuel cell as described in claim 1, characterized in that, Step S2-1, calculating the mass flow rate of hydrogen at various points in the gas flow path, is as follows: The mass flow rate of hydrogen gas newly entering the ejector Calculate using the following formula: （2）； In the formula, Where is the molar mass of hydrogen, N is the number of individual cells in the fuel cell stack, I is the current generated by the fuel cell, and F is the Faraday constant. This is a correction parameter for hydrogen utilization, typically set to 1.04; The mass flow rate of hydrogen gas ejected from the ejector before entering the plate heat exchanger is equal to the sum of the mass flow rate of hydrogen gas newly entering the ejector and the mass flow rate of hydrogen gas returning from the fuel cell stack to the ejector: （3）； Mass flow rate of hydrogen after exiting the plate heat exchanger The mass flow rate of hydrogen gas before it exits the ejector and enters the plate heat exchanger They are equal, therefore the following relationship exists: （4）。 3. The method for online calculation of anode impurity gas concentration in a fuel cell as described in claim 2, characterized in that, Step S2-3, calculating the mass flow rate of gaseous and liquid water at various points in the gas flow path, specifically involves the following steps: S2-3-1. Calculate the mass fraction of gaseous water at various points in the gas flow path. ; S2-3-2. Calculate the mass flow rate of gaseous water entering the fuel cell stack. ; S2-3-3. Calculate the mass flow rate of gaseous water before it exits the ejector and enters the plate heat exchanger. ; S2-3-4. Calculate the mass flow rate of gaseous water flowing back into the ejector from the fuel cell stack. ; S2-3-5. Calculate the mass flow rate of liquid water flowing back from the fuel cell stack into the ejector. and the mass flow rate of liquid water before it exits the ejector and enters the plate heat exchanger .

4. The method for online calculation of anode impurity gas concentration in a fuel cell as described in claim 3, characterized in that, Step S2-3-1 calculates the mass fraction of gaseous water at various points in the gas flow path. Specifically as follows: The gaseous water pressure at various points in the gas flow path is calculated using the following formula: （5）； In the formula, RH is the gaseous water pressure at that point in the gas flow path, RH is the relative humidity of the gas at that point in the gas flow path, and T is the gas temperature at that point in the gas flow path. RH and T are measured by the humidity sensor and temperature sensor arranged at that point in the gas flow path. The mass fraction of gaseous water at various points in the gas flow path is calculated using the following formula: （6）； In the formula, This represents the mass fraction of gaseous water at that point in the gas flow path. This represents the gaseous water pressure at that point in the gas flow path. The molar mass of water, P represents the molar mass of hydrogen and impurities in the mixed gas at that location, and P is the gas pressure at that location in the gas flow path, which is measured by a pressure sensor located at that location in the gas flow path.

5. The method for online calculation of anode impurity gas concentration in a fuel cell as described in claim 4, characterized in that, Step S2-3-2 calculates the mass flow rate of the gaseous water entering the fuel cell stack. Specifically as follows: The mixed gas ejected from the ejector is heated by a plate heat exchanger, and the liquid water in the mixed gas vaporizes and is completely converted into gaseous water. The mass flow rate of the gaseous water entering the fuel cell stack is... Calculated using the following formula; （7）； In the formula, This represents the mass flow rate of hydrogen and impurities in the mixed gas after exiting the plate heat exchanger. The mass fraction of gaseous water after passing through the plate heat exchanger. It is calculated using formulas (5) and (6); Mass flow rates of hydrogen and impurities in the mixed gas after the plate heat exchanger The mass flow rate of hydrogen and impurities in the mixed gas before it exits the ejector and enters the plate heat exchanger They are equal, therefore the following relationship exists: （8）； The mass flow rate of hydrogen and impurities in the mixed gas ejected from the ejector before entering the plate heat exchanger. The mass flow rate of hydrogen gas newly entering the ejector and the mass flow rate of hydrogen returning from the fuel cell stack to the ejector and the mass flow rate of impurity gases in the gas flow path Since their sums are equal, the following relationship exists: （9）； The mixed molar mass of hydrogen and impurities in the gas mixture after passing through the plate heat exchanger Calculated by the following formula: （10）； In the formula, α is the concentration of anode impurity gas. Here is the molar mass of nitrogen. denoted as , where is the molar mass of hydrogen gas.

6. The method for online calculation of anode impurity gas concentration in a fuel cell as described in claim 5, characterized in that, Step S2-3-3 calculates the mass flow rate of the gaseous water before it exits the ejector and enters the plate heat exchanger. Specifically as follows: The mass flow rate of gaseous water ejected from the ejector before entering the plate heat exchanger Calculated using the following formula: （11）； In the formula, The mass flow rate of hydrogen and impurities in the mixed gas before it exits the ejector and enters the plate heat exchanger. The mass fraction of gaseous water ejected from the ejector before entering the plate heat exchanger. It is calculated using formulas (5) and (6); The molar mass of hydrogen and impurities in the mixed gas before it exits the ejector and enters the plate heat exchanger The molar mass of hydrogen and impurities in the mixed gas after passing through the plate heat exchanger. They are equal, therefore the following relationship exists: （12）。 7. The method for online calculation of anode impurity gas concentration in a fuel cell as described in claim 6, characterized in that, Step S2-3-4 calculates the mass flow rate of gaseous water flowing back into the ejector from the fuel cell stack. Specifically as follows: Mass flow rate of gaseous water flowing back into the ejector from the fuel cell stack Calculated using the following formula: （13）； In the formula, This refers to the mass flow rate of hydrogen and impurities in the mixed gas flowing back from the fuel cell stack into the ejector. The mass fraction of gaseous water flowing back from the fuel cell stack into the ejector. It is calculated using formulas (5) and (6); Mass flow rate of hydrogen and impurities in the mixed gas flowing back into the ejector from the fuel cell stack Mass flow rate of hydrogen entering the ejector The sum equals the mass flow rates of hydrogen and impurities in the mixed gas before it exits the ejector and enters the plate heat exchanger. That is, the following formula exists: （14）； According to the law of conservation of substance, the following relationship exists: （15）； In the formula, The molar mass of hydrogen and impurities in the mixed gas flowing back from the fuel cell stack into the ejector.

8. The method for online calculation of anode impurity gas concentration in a fuel cell as described in claim 7, characterized in that, Step S2-3-5 calculates the mass flow rate of liquid water flowing back from the fuel cell stack into the ejector. and the mass flow rate of liquid water before it exits the ejector and enters the plate heat exchanger Specifically as follows: Due to the conservation of water mass at all points in the gas flow path, the following relationship exists: （16）。 9. The method for online calculation of anode impurity gas concentration in a fuel cell as described in claim 8, characterized in that, Step S2-4, calculating the anode impurity gas concentration α, is as follows; According to the law of conservation of energy, the sum of the energy of the new hydrogen entering the ejector and the energy of the gas flowing back into the ejector from the fuel cell stack is equal to the energy of the gas ejected from the ejector before entering the plate heat exchanger. （17）； The sum of the energy of the gas ejected from the ejector before entering the plate heat exchanger and the energy provided by the plate heat exchanger in converting liquid water into gaseous water is equal to the energy of the gas after passing through the plate heat exchanger. （18）； In the formula, The specific heat capacity of hydrogen. The specific heat capacity of gaseous water, The specific heat capacity of liquid water, The specific heat capacity of nitrogen is... The temperature of the hydrogen gas newly entering the ejector. The temperature was measured by the first temperature sensor located at the hydrogen inlet of the newly introduced ejector. The temperature of the gas flowing back into the ejector from the fuel cell stack. The temperature was measured by a second temperature sensor located at the gas inlet flowing back into the ejector from the fuel cell stack. The temperature of the gas ejected from the ejector before entering the plate heat exchanger. The temperature was measured by a third temperature sensor located at the inlet of the plate heat exchanger. The temperature of the gas after passing through the plate heat exchanger. The temperature was measured by a fourth temperature sensor located at the outlet of the plate heat exchanger. The temperature of the liquid water at the outlet of the plate heat exchanger. The temperature was measured by the fifth temperature sensor located at the outlet of the plate heat exchanger. The temperature of the liquid water at the inlet of the plate heat exchanger. The temperature was measured by the sixth temperature sensor located at the inlet of the plate heat exchanger; In the formula, The mass flow rate of liquid water in the plate heat exchanger is measured by a flow meter located at the outlet of the plate heat exchanger. Substituting the mass flow rates of hydrogen, gaseous water, and liquid water at various points in the gas flow path, as well as the mass flow rate of the impurity gas nitrogen, obtained from steps S2-1, S2-2, and S2-3, into formulas (17) and (18), we obtain two equations containing two unknowns, namely, And α, solve for the value of the anode impurity gas concentration α.

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