Fuel cell water balance test system and method

Abstract

The fuel cell water balance test system comprises an anode gas inlet assembly, a cathode gas inlet assembly, a fuel cell, a current sensor, an anode exhaust assembly and a cathode exhaust assembly, the anode gas inlet assembly and the cathode gas inlet assembly are connected with an anode and a cathode of the fuel cell respectively, and the anode exhaust assembly and the cathode exhaust assembly are connected with the fuel cell; the current sensor is connected with the fuel cell. The invention also discloses a fuel cell water balance test method. The method comprises the following steps: calculating the anode humidifying water amount and the cathode humidifying water amount of the gas inlet end according to the gas flow, the gas pressure and the gas dew point of the gas inlet end; the water quantity generated by the reaction of the fuel cell is calculated according to the current measured by the current sensor; calculating the anode displacement and the cathode displacement of the exhaust end according to the gas flow, the gas pressure and the gas dew point of the exhaust end; and judging the water balance condition in the fuel cell according to the data. The water balance testing device has the beneficial effect of high water balance testing precision.

Description

Technical Field

[0001] The present invention relates to the field of hydrogen fuel cell testing, and particularly to a fuel cell water balance testing system and method. Background Art

[0002] A hydrogen fuel cell is a device that uses hydrogen and oxygen as raw fuels to convert chemical energy into electrical energy. Fuel cells have characteristics such as high energy conversion efficiency and zero pollution, so they have broad application prospects. The fuel cell testing system mainly provides a stable, safe, and convenient testing platform for fuel cells. The management of the water volume inside the fuel cell has an important impact on the battery performance. Insufficient water volume will cause the electrolyte membrane to dry out, increase the battery internal resistance, and reduce the output voltage; while excessive water content will hinder the diffusion of fuel gas, which will also lead to a decrease in the output voltage. Therefore, fuel cell water balance testing is an important means to evaluate battery performance and optimize battery structure.

[0003] CN117855529A discloses a fuel cell water balance testing system, which includes a stack, humidity sensors, temperature sensors, and a control and calculation element. Humidity sensors and temperature sensors are respectively arranged at the inlet and outlet of the stack. The retained water volume inside the stack is judged according to the calculated net inflow water content into the stack, and then the control and calculation element is used to control and adjust the intake humidity of the humidifying tank, so as to finally keep the water content inside the stack balanced. However, this water balance testing system ignores the working pressure during normal stack operation. The saturated moisture content is different under different pressures, and this system ignores that high-humidity gas is easy to condense and does not perform heat preservation and tracing treatment. The high-precision dew point sensor has inaccurate measurements in high humidity or even in the presence of liquid water. In addition, the measurement of the electronic scale is also inaccurate under different pressures.

[0004] CN110429306A discloses a fuel cell water balance testing device and method. The invention provides a fuel cell water balance testing device and method, aiming to maintain the water balance in the proton exchange membrane fuel cell and improve the battery performance and lifespan. The device includes an anode outlet dew point measuring device, a cathode outlet dew point measuring device, an anode heating device, a cathode heating device, and a current measuring device. The anode heating device is used to heat the gas guiding pipeline connected to the anode exhaust port to vaporize the water discharged from the anode exhaust port; the cathode heating device is used to heat the gas guiding pipeline connected to the cathode exhaust port to vaporize the water discharged from the cathode exhaust port. In addition, it also includes an anode humidifier, a cathode humidifier, an anode inlet dew point measuring device, and a cathode inlet dew point measuring device. The invention ignores the measurement of the flow rate and pressure of the anode and cathode at the stack inlet. The saturated moisture content of the gas is completely different under different flow rates and pressures. In addition, the efficiency of directly heating liquid water to complete vaporization is not evaluated, and there is a problem that some liquid water is not completely vaporized, resulting in inaccurate measurement.

[0005] The existing systems and methods for fuel cell water balance testing cannot fully meet the requirements. The measured data is incomplete and inaccurate, with large errors and low precision. Research has found that the following main problems exist:

[0006] On the one hand, the fuel cell water balance testing system is incomplete, neglecting the measurement of gas flow and the inlet pressure of the stack, resulting in the inability to calculate the actual water content at the stack inlet. Additionally, the basic operating pressure range of the fuel cell stack is ignored, and the data obtained from the test is not the data during the actual operation of the stack;

[0007] On the other hand, the measurement of liquid water in fuel cell water balance testing is inaccurate. Some existing technologies neglect the measurement of liquid water, and another part of the existing technologies do not evaluate the efficiency of directly heating liquid water to complete vaporization, resulting in inaccurate measurement due to incomplete vaporization of some liquid water.

[0008] The information disclosed in this background art section is only intended to enhance the overall understanding of the present invention and should not be regarded as an admission or any form of implication that this information constitutes prior art known to those of ordinary skill in the art. Summary of the Invention

[0009] The technical problem to be solved by the present invention is: how to solve the problems of incomplete and inaccurate measured data in the prior art, with large errors and low precision.

[0010] The present invention solves the above technical problems through the following technical means:

[0011] A fuel cell water balance testing system, including an anode inlet assembly, a cathode inlet assembly, a fuel cell, a current sensor, an anode exhaust assembly, and a cathode exhaust assembly. The anode inlet assembly and the cathode inlet assembly are respectively connected to the anode and the cathode of the fuel cell, and the anode exhaust assembly and the cathode exhaust assembly are connected to the fuel cell; the current sensor is connected to the fuel cell;

[0012] Both the anode inlet assembly and the cathode inlet assembly include a dry gas path and a wet gas path. The dry gas path is sequentially connected to a first mass flow controller, a first dew point sensor, and a first pressure sensor, and the wet gas path is sequentially connected to a second mass flow controller and a humidification module; the end of the humidification module is connected to the wet gas path;

[0013] The tail exhaust discharge pipelines of the anode exhaust assembly and the cathode exhaust assembly are sequentially connected to a gas-liquid separator, a second dew point sensor, and a third pressure sensor.

[0014] In the fuel cell water balance test system of the present invention, sampling of current sensors, gas flow controllers, dew point sensors, and anode and cathode inlet and outlet stack pressure sensors is added. The gas water content at the inlet of the stack is accurately calculated based on flow rate, pressure, and dew point values. The water production is measured through the current, and the gas water content at the outlet is calculated through flow rate, dew point, and pressure. During the operation of the fuel cell, the sources of water mainly include the water generated by the reaction and the water entering through external humidification. By measuring the flow and change of this water, the water balance state of the fuel cell is evaluated. The present invention simultaneously considers three influencing factors: flow rate, pressure, and dew point, has high test water balance accuracy, a simple structure, a small volume, a simple control logic, good stability, and is convenient for installation and later maintenance.

[0015] Preferably, a first pneumatic control valve, a first mass flow controller, a first one-way valve, a heater, a first temperature sensor, a first dew point sensor, a first pressure sensor, and a second temperature sensor are sequentially connected to the dry gas pipeline.

[0016] Preferably, a third pneumatic control valve, a second mass flow control valve, a second one-way valve, a humidification module, and a second pneumatic control valve are sequentially connected to the wet gas pipeline, and the end of the wet gas pipeline is connected between the first one-way valve and the heater; the fuel gas enters the fuel cell after being mixed in the dry gas pipeline and the wet gas pipeline.

[0017] Preferably, the tail exhaust pipes of the anode exhaust assembly and the cathode exhaust assembly are sequentially connected to a gas-water separator, a second dew point sensor, a third pressure sensor, and a third temperature sensor. The bottom of the gas-water separation device is also connected to a first exhaust pipe, and a second pressure sensor and a solenoid valve are connected to the first exhaust pipe.

[0018] A fuel cell water balance test method using the above fuel cell water balance test system includes the following steps:

[0019] S1: Calculate the anode humidification water volume and the cathode humidification water volume at the intake end according to the gas flow rate, gas pressure, and gas dew point at the intake end;

[0020] S2: Calculate the water volume generated by the fuel cell reaction according to the current measured by the current sensor;

[0021] S3: Calculate the anode drainage volume and the cathode drainage volume at the exhaust end according to the gas flow rate, gas pressure, and gas dew point at the exhaust end;

[0022] Judge the internal water balance situation of the fuel cell according to the above data.

[0023] Preferably, in S1, the anode humidification water volume and the cathode humidification water volume are respectively obtained through Formula 1;

[0024]

[0025] Among them, V is obtained from the sum of the first mass flow controller 102 and the second mass flow control valve;

[0026] T d is measured by the first dew point sensor;

[0027] A, B, and C are constants of the Antoine equation, which depend on the type of gas and are obtained by looking up the table;

[0028] R is the universal gas constant, R = 8.314 J / (mol·K);

[0029] M water is the molar mass of water, which is 18 g / mol;

[0030] P total is measured by the first pressure sensor.

[0031] Preferably, in S2, the calculation formula for the amount of water generated by the fuel cell reaction calculated according to the current measured by the current sensor is:

[0032]

[0033] Among them, the current I is measured by the current sensor or a known current value;

[0034] Faraday constant F: F = 96485 C / mol

[0035] The number of electrons transferred per mole of reactant n: For PEMFC, n = 2.

[0036] Preferably, in S3, the anode drainage volume is the sum of the water in the water-gas separation device in the anode exhaust assembly and the drainage volume in the tail exhaust pipe; the cathode drainage volume is the sum of the water in the water-gas separation device in the cathode exhaust assembly and the drainage volume in the tail exhaust pipe.

[0037] Preferably, in S3, the total gas flow rates measured first by the first mass flow controller and the second mass flow control valve in the anode intake assembly and the cathode intake assembly are respectively The fuel cell theoretical consumption flow rate is calculated by Faraday's law and the theory of electrochemical reaction, and the consumption flow rates are respectively denoted as The difference between the two (V 差值 ) is the gas volume discharged from the tail exhaust pipe;

[0038] Among them,

[0039]

[0040] On the hydrogen side Substituting into the above formula (2) gives the drainage volume in the tail exhaust pipe on the hydrogen side, denoted as m 阳极尾管水 ;

[0041] Substitute the on the oxygen side into the above formula (2) to obtain the drainage volume in the tail exhaust pipe on the oxygen side, denoted as m 阳极尾管水 .

[0042] m 阳极排水 = m 气水分离器1 + m 阳极尾管水 ;

[0043] m 阴极排水 = m 气水分离器2 + m 阴极尾管水 ;

[0044] Among them, the data of the gas-liquid separator in the anode exhaust assembly is denoted as m 气水分离器1 , and the data of the gas-liquid separator in the cathode exhaust assembly is denoted as m 气水分离器2 .

[0045] Preferably, if the anode humidifying water + cathode humidifying water + generated water = anode drainage + cathode drainage, it indicates that the water balance state is reached; if the anode humidifying water + cathode humidifying water + generated water > anode drainage + cathode drainage, it indicates waterlogging inside the fuel cell stack; if the anode humidifying water + cathode humidifying water + generated water < anode drainage + cathode drainage, it indicates excessive dryness inside the fuel cell stack.

[0046] The advantages of the present invention are as follows:

[0047] By arranging dew point sensors, temperature sensors and pressure sensors at the inlet and outlet of the fuel cell, the present invention can accurately measure the humidifying water volume and drainage volume of the fuel cell, and current sensors are provided at the positive and negative electrodes of the fuel cell to accurately calculate the water generated by the fuel cell reaction; the water vapor separation device can effectively reduce the temperature and humidity of the gas after the fuel cell reaction. The present invention simultaneously considers three influencing factors of flow rate, pressure and dew point, has high test water balance accuracy, solves the problem that the high-precision dew point sensor cannot measure accurately under high humidity or in the presence of liquid water; solves the problem of poor test accuracy of the water balance test of most existing test benches at present.

[0048] The water vapor separation device of the present invention is added with a differential pressure type liquid level gauge, and the mass of the liquid water is calculated in real time through the liquid level height and the cross-sectional area of the liquid storage pipe for water vapor separation, so as to achieve real-time collection and calculation of the liquid water, and can meet different working conditions of the normal operation of the fuel cell, and is not affected by the working pressure.

[0049] The present invention adds heat preservation cotton and tracing tape to the tail exhaust pipe for heat preservation and tracing treatment to reduce the test error caused by the condensation of the tail exhaust gas.

[0050] The structure of the present invention is simple, with a small volume, simple control logic, good stability, and is convenient for installation and later maintenance. Description of the Drawings

[0051] Figure 1 It is a schematic structural diagram of the fuel cell water balance test system according to an embodiment of the present invention;

[0052] Figure 2 It is a schematic structural diagram of the fuel cell water balance test system (only the anode) according to an embodiment of the present invention;

[0053] Reference numerals in the figures:

[0054] 100, Anode intake assembly; 101, First air control valve; 102, First mass flow controller; 103, First one-way valve; 104, Heater; 105, First temperature sensor; 106, First dew point sensor; 107, First pressure sensor; 108, Second temperature sensor; 109, Third air control valve; 110, Second mass flow control valve; 111, Second one-way valve; 112, Humidification module; 113, Second air control valve;

[0055] 500, Cathode intake assembly;

[0056] 200, Fuel cell;

[0057] 300, Current sensor;

[0058] 400, Anode exhaust assembly; 401, Water-gas separation device; 402, Second dew point sensor; 403, Third pressure sensor; 404, Third temperature sensor; 405, Second pressure sensor; 406, Solenoid valve;

[0059] 600, Cathode exhaust assembly. Detailed Embodiments

[0060] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Apparently, 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 shall fall within the protection scope of the present invention.

[0061] Embodiment 1:

[0062] As Figure 1 、 Figure 2As shown in the figure, the fuel cell water balance test system includes an anode intake assembly 100, a cathode intake assembly 500, a fuel cell 200, a current sensor 300, an anode exhaust assembly 400, and a cathode exhaust assembly 600. The anode intake assembly 100 and the cathode intake assembly 500 are respectively connected to the anode and cathode of the fuel cell 200, and the anode exhaust assembly 400 and the cathode exhaust assembly 600 are connected to the fuel cell 200. The composition and connection methods of the anode intake assembly 100 and the cathode intake assembly 200 are the same, and the composition and connection methods of the anode exhaust assembly 400 and the cathode exhaust assembly 600 are the same. The current sensor 300 is connected to the fuel cell 200 and is used to measure the amount of water generated by the fuel cell reaction according to the magnitude of the current.

[0063] In this embodiment, the anode intake assembly 100 and the anode exhaust assembly 400 are used for illustration.

[0064] As Figure 1 shown in the figure, the anode intake assembly 100 includes a dry gas pipeline and a wet gas pipeline. The dry gas pipeline is sequentially connected with a first gas control valve 101, a first mass flow controller 102, a first one-way valve 103, a heater 104, a first temperature sensor 105, a first dew point sensor 106, a first pressure sensor 107, and a second temperature sensor 108. The wet gas pipeline is sequentially connected with a third gas control valve 109, a second mass flow control valve 110, a second one-way valve 111, a humidification module 112, and a second gas control valve 113. The end of the wet gas pipeline is connected between the first one-way valve 103 and the heater 104. The dry gas and the wet gas are mixed and then enter the fuel cell 200.

[0065] The anode exhaust assembly 400 includes an exhaust gas evacuation pipeline, which is sequentially connected with a water-gas separation device 401, a second dew point sensor 402, a third pressure sensor 403, and a third temperature sensor 404. The water-gas separation device 401 is also connected to a first evacuation pipeline, and the first evacuation pipeline is connected with a second pressure sensor 405 and a solenoid valve 406.

[0066] The working principle of this embodiment is as follows:

[0067] During the operation of the fuel cell 200, the sources of water mainly include the water generated by the reaction and the water entering from external humidification. By measuring the flow and change of this water, the water balance state of the fuel cell 200 is evaluated. By detecting the water content in the fuel cell (anode humidification water, cathode humidification water), the water volume in the water-gas separation device and the water volume carried away by the tail gas (anode drainage + cathode drainage), the water volume remaining in the fuel cell 200 (generated water) is calculated to judge the water balance state in the fuel cell 200.

[0068] The judgment formula for water balance is: whether (anode humidifying water + cathode humidifying water + generated water) is equal to (anode drainage + cathode drainage); if anode humidifying water + cathode humidifying water + generated water = anode drainage + cathode drainage, it indicates that the fuel cell reaches the water balance state; if anode humidifying water + cathode humidifying water + generated water > anode drainage + cathode drainage, it indicates that there is waterlogging inside the fuel cell; if anode humidifying water + cathode humidifying water + generated water < anode drainage + cathode drainage, it indicates that the inside of the fuel cell is too dry.

[0069] Among them, anode drainage = water in the water-gas separation device in the anode exhaust assembly + drainage in the tail exhaust pipe;

[0070] Cathode drainage = water in the water-gas separation device in the cathode exhaust assembly + drainage in the tail exhaust pipe.

[0071] In this embodiment, the anode is taken as an example. During the fuel cell test process, the fuel gas enters the humidification module 112 along the humid air path for humidification, and then the humidified gas enters the heater 104 for heating up. When the gas temperature and dew point temperature reach the target values, the fuel cell 200 conducts a normal polarization test. At this time, a first dew point sensor 106, a first pressure sensor 107, and a second temperature sensor 108 are provided at the inlet of the fuel cell. The water content in the gas can be calculated based on the gas flow rate, dew point, and pressure. The fuel gas reacts through the fuel cell 200 and is discharged from the outlet. The tail exhaust gas undergoes gas-liquid separation through the water-gas separation device 401, and the liquid will flow into the bottom of the water-gas separation device. A differential pressure type liquid level gauge is installed at the bottom of the water-gas separation device 401, and the liquid content in the water-gas separation device can be measured according to the different pressures. The gas separated by the water-gas separation device is emptied through the tail exhaust pipe. A second dew point sensor 402, a third pressure sensor 403, and a third temperature sensor 404 are provided between the water-gas separation device 401 and the tail exhaust pipe, and the water content in the tail exhaust gas can be calculated based on the gas flow rate, dew point, and pressure.

[0072] Specifically, the fuel cell water balance test method includes the following steps:

[0073] S1: Calculate the water content of the gas at the intake end according to the gas flow rate, gas pressure, and gas dew point at the intake end;

[0074] 1. Calculate the saturated water vapor pressure

[0075] The saturated water vapor pressure P w can be calculated through the gas dew point temperature T d and is usually calculated using the Antoine equation:

[0076]

[0077] Among them, A, B, and C are the constants of the Antoine equation, which depend on the type of gas (for water vapor, the constants can be obtained from a table).

[0078] T d is the dew point temperature of the gas, in degrees Celsius.

[0079] 2. Calculate the partial pressure of water vapor

[0080] The partial pressure of water vapor P vap can be calculated through the relative humidity φ and the saturated water vapor pressure P w as follows:

[0081] P vap = φ × P w

[0082] In fuel cell testing, it is usually assumed that the gas is completely saturated, that is, the relative humidity φ = 1. Therefore,

[0083] P vap = P w

[0084] 3. Calculate the mole fraction of water vapor

[0085] The mole fraction of water vapor x vap can be calculated through the partial pressure of water vapor P vap and the total gas pressure P total as follows:

[0086]

[0087] 4. Calculate the water content of the gas

[0088] The water content of the gas m water can be calculated through the mole fraction of water vapor x vap , the gas flow rate and the molar mass of the gas M water as follows:

[0089]

[0090] Among them, is the gas flow rate, in standard cubic meters per second (m 3 / s)

[0091] R is the universal gas constant, R = 8.314 J / (mol·K)

[0092] T is the absolute temperature of the gas, in Kelvin (K)

[0093] M water is the molar mass of water, 18 g / mol.

[0094] It should be noted that: the gas flow rate is the actual flow rate, but the flow rate V measured by the mass flow controller is under standard conditions (the standard pressure is usually 1 atm (101.325 kPa)), so the actual also needs to be converted according to the ideal gas law as follows:

[0095]

[0096] Comprehensive formula:

[0097]

[0098] After simplification:

[0099]

[0100] Then substitute into the above formula, and finally obtain:

[0101]

[0102] Among them, V is obtained from the sum of the first mass flow controller 102 and the second mass flow control valve 110, T d is measured by the first dew point sensor, and A, B, C, R, Mwater are all known values. P total is measured by the first pressure sensor 107. Through the above formula, the water content of the gas can be calculated based on the gas flow rate, gas pressure, and gas dew point.

[0103] It should be noted that the dew point is different under different pressures, and the corresponding water content is also different. When the pressure of the gas increases, the distance between gas molecules becomes smaller, and water vapor molecules are more likely to interact with other gas molecules to form liquid water. Therefore, the dew point temperature of the gas will increase with the increase of pressure. When the pressure of the gas decreases, the distance between gas molecules becomes larger, and water vapor molecules are more likely to escape from liquid water to form gaseous water. Therefore, the dew point temperature of the gas will decrease with the decrease of pressure. The dew point temperature is an important indicator to measure the water vapor content in the gas. The higher the dew point temperature, the higher the water vapor content in the gas; the lower the dew point temperature, the lower the water vapor content in the gas. Under different pressures, even if the dew point temperatures are the same, the water content of the gas will be different. This is because the pressure change will affect the saturated water vapor pressure of the gas. Also, because the water content of the gas cannot be directly calculated only through the gas pressure and flow rate. This is because the water content of the gas is closely related to the dew point temperature of the gas, and the dew point temperature is an important parameter reflecting the water vapor content in the gas. Without information on the dew point temperature, we cannot determine the partial pressure of water vapor in the gas, and thus cannot calculate the water content of the gas. Therefore, it is accurate to consider the water content under the combined action of the three factors of gas flow rate, gas pressure, and gas dew point as a whole.

[0104] The anode humidifying water and the cathode humidifying water are respectively calculated and obtained by using the above formula (1), and are respectively denoted as m 阳极增湿水 、m 阴极增湿水 . The water in the water-gas separation device is directly read by the water-gas separation device. The data of the gas-water separator in the anode exhaust assembly is denoted as m 气水分离器1 , and the data of the gas-water separator in the cathode exhaust assembly is denoted as m 气水分离器2 .

[0105] S2: Current sensors 300 are provided at the positive and negative electrodes of the fuel cell, and the amount of water generated by the fuel cell reaction can be calculated according to the magnitude of the current. The following is the calculation formula:

[0106] 1. Electrochemical reaction equation

[0107] The electrochemical reaction equation of PEMFC is:

[0108] Anode reaction: H 2 →2H + +2e -

[0109] Cathode reaction:

[0110] 2. Calculation formula

[0111] According to Faraday's law, the relationship between the current I and the number of moles N of the reactants is:

[0112]

[0113] Among them, I is the current (unit: ampere, A).

[0114] n is the number of electrons transferred per mole of reactant (for PEMFC, n = 2).

[0115] F is the Faraday constant (F = 96485 C / mol).

[0116] is the rate of change of the number of moles of reactant (unit: mol / s).

[0117] 3. Calculation of the amount of water generated

[0118] According to the above formula, the calculation formula for the amount of water generated can be derived:

[0119]

[0120] Among them, is the rate of change of the number of moles of water generated (unit: mol / s).

[0121] 4. Specific calculation steps

[0122] (1) Determine the current I: Measure it through the current sensor 300 or use the known current value.

[0123] (2) Determine the Faraday constant F: F = 96485 C / mol

[0124] (3) Determine the number of electrons transferred per mole of reactant n: For PEMFC, n = 2.

[0125] (4) Calculate the rate of change of the number of moles of water generated:

[0126]

[0127] 5. Example

[0128] Assume I = 10 A and calculate the rate of change of the number of moles of water generated:

[0129] 6. Conversion to volume or mass

[0130] If it is necessary to convert the number of moles of water generated to volume or mass, the molar mass and density of water can be used:

[0131] The molar mass of water M water = 18 g / mol;

[0132] The density of water ρ water = 1 g / cm 3

[0133] Mass change rate of generated water:

[0134]

[0135] Volume change rate of generated water:

[0136]

[0137] Through the above formulas and steps, the amount of water generated by the PEMFC reaction can be calculated based on the magnitude of the current.

[0138] S3: Calculate the drainage volume in the tail exhaust pipe

[0139] The drainage volume in the tail exhaust pipe is still calculated using Formula 1. However, since directly measuring the flow rate in the tail exhaust pipe is not accurate, the total gas flow rate measured by the first mass flow controller 102 and the second mass flow control valve 110 is used. The theoretical consumption flow rate of the fuel cell can be calculated by the Faraday's law and the theory of electrochemical reactions. The difference between the two (V 差值H2 , V 差值O2 ) is the gas volume discharged from the tail exhaust pipe.

[0140]

[0141] Bring the on the hydrogen side into the above Formula 2 to obtain the drainage volume in the tail exhaust pipe on the hydrogen side, denoted as m 阳极尾管水 ;

[0142] Bring the on the oxygen side into the above Formula 2 to obtain the drainage volume in the tail exhaust pipe on the oxygen side, denoted as m 阳极尾管水 .

[0143] m 阳极排水 = m 气水分离器1 + m 阳极尾管水 ;

[0144] m 阴极排水 = m 气水分离器2 + m 阴极尾管水 .

[0145] Finally, the judgment formula for water balance is: whether (anode humidifying water + cathode humidifying water + generated water) is equal to (anode drainage + cathode drainage);

[0146] If m 阳极增湿水 + m 阴极增湿水 + m 产生水 = m 阳极排水 + m 阴极排水 , it indicates that the fuel cell reaches the water balance state;

[0147] If m 阳极增湿水 + m 阴极增湿水 + m 产生水 > m 阳极排水 + m 阴极排水 , it indicates that there is waterlogging inside the fuel cell;

[0148] If m 阳极增湿水 + m 阴极增湿水 + m 产生水 < m 阳极排水 + m 阴极排水 , it indicates that the inside of the fuel cell is over-dry.

[0149] In this embodiment, the fuel cell water balance test system adds sampling of current sensors, gas flow controllers, dew point sensors, and anode and cathode inlet and outlet stack pressure sensors, and performs heat tracing treatment on the inlet and outlet stack pipelines. This method can solve the problems of liquid water generation and inaccurate dew point measurement caused by high humidity condensation, and can also meet the requirements of accurately calculating the gas water content at the inlet of the stack under different operating conditions of the stack according to flow, pressure, and dew point values. A water-gas separation device is added before the stack outlet and the dew point sensor to ensure the collection of liquid water at the stack outlet, reduce the outlet humidity, measure the dew point value of the low-humidity gas through the dew point sensor, and add a pressure sensor at the dew point measurement point after the water-gas separation device, so that the gas water content at the outlet can be calculated through flow, dew point, and pressure. It solves the problem of poor test accuracy of the water balance test of most existing test benches, and can meet the normal operation of fuel cells under different operating conditions, is not affected by the working pressure, and improves the versatility of the test bench.

[0150] In this embodiment, the water-gas separation device is added with a differential pressure type liquid level gauge, and the mass of liquid water is calculated in real time through the liquid level height and the cross-sectional area of the liquid storage pipe for water-gas separation, so as to achieve real-time collection and calculation of liquid water, and can meet different operating conditions of the normal operation of the fuel cell, and is not affected by the working pressure.

[0151] In this embodiment, heat preservation cotton and heat tracing belts are provided in the fuel cell outlet pipeline to perform heat tracing treatment on the fuel cell outlet gas, prevent gas condensation, and reduce the water balance test error.

[0152] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; 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 they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A fuel cell water balance test system, characterized in that: It includes an anode air intake assembly, a cathode air intake assembly, a fuel cell, a current sensor, an anode exhaust assembly, and a cathode exhaust assembly. The anode air intake assembly and the cathode air intake assembly are respectively connected to the anode and cathode of the fuel cell, and the anode exhaust assembly and the cathode exhaust assembly are connected to the fuel cell; the current sensor is connected to the fuel cell; The anode air intake assembly and the cathode air intake assembly both include a dry gas path and a wet gas path, the dry gas path is sequentially connected to a first mass flow controller, a first dew point sensor, and a first pressure sensor, and the wet gas path is sequentially connected to a second mass flow controller and a humidification module; the end of the humidification module is connected to the wet gas path; The tail exhaust pipes of the anode exhaust assembly and the cathode exhaust assembly are connected to the gas-water separator, the second dew point sensor, and the third pressure sensor in sequence.

2. The fuel cell water balance test system according to claim 1, characterized in that: The dry gas pipeline is sequentially connected to a first gas control valve, a first mass flow controller, a first one-way valve, a heater, a first temperature sensor, a first dew point sensor, a first pressure sensor, and a second temperature sensor.

3. The fuel cell water balance test system according to claim 2, characterized in that: The wet gas pipeline is connected to a third gas control valve, a second mass flow control valve, a second one-way valve, a humidification module, and a second gas control valve in sequence, wherein the end of the wet gas pipeline is connected between the first one-way valve and the heater; the fuel gas is mixed in the dry gas pipeline and the wet gas pipeline and then enters the fuel cell.

4. The fuel cell water balance test system according to claim 2, characterized in that: The tail exhaust pipes of the anode exhaust assembly and the cathode exhaust assembly are connected to the gas-water separator, the second dew point sensor, the third pressure sensor, and the third temperature sensor in sequence, wherein the bottom of the water-gas separation device is also connected to the first exhaust pipe, and the first exhaust pipe is connected to the second pressure sensor and the solenoid valve.

5. A fuel cell water balance test method, characterized in that: A fuel cell water balance test system according to any one of claims 1 to 4, comprising the following steps: S1: Calculate the anode humidification water volume and cathode humidification water volume at the inlet end according to the gas flow, gas pressure and gas dew point at the inlet end; S2: Calculate the amount of water generated by the fuel cell reaction based on the current measured by the current sensor; S3: Calculate the anode water discharge and cathode water discharge at the exhaust end according to the gas flow, gas pressure and gas dew point at the exhaust end; The water balance inside the fuel cell is determined based on the above data.

6. The fuel cell water balance test method according to claim 5, characterized in that: In S1, the anode humidification water volume and the cathode humidification water volume are obtained respectively by formula 1; Wherein, V is obtained by the sum of the first mass flow controller 102 and the second mass flow control valve; T d Measured by the first dew point sensor; A, B, and C are constants of the Antoine equation, which depend on the type of gas and are obtained by looking up the table; R is the universal gas constant, R = 8.314 J / (mol·K); M water is the molar mass of water, 18 g / mol; P total Measured by the first pressure sensor.

7. The fuel cell water balance test method according to claim 5, characterized in that: In S2, the amount of water generated by the fuel cell reaction is calculated based on the current measured by the current sensor: Wherein, the current I is measured by a current sensor or is a known current value; Faraday constant F: F = 96485C / mol The number of electrons transferred per mole of reactant, n: for PEMFC, n=2.

8. The fuel cell water balance test method according to claim 5, characterized in that: In S3, the anode drainage is the sum of the water in the water-gas separation device in the anode exhaust assembly and the drainage in the tail discharge pipe; the cathode drainage is the sum of the water in the water-gas separation device in the cathode exhaust assembly and the drainage in the tail discharge pipe.

9. The fuel cell water balance test method according to claim 8, characterized in that: In S3, the total gas flow rates measured by the first mass flow controller and the second mass flow control valve in the anode gas inlet assembly and the cathode gas inlet assembly are respectively The theoretical consumption flow of the fuel cell is calculated by Faraday's law and the theory of electrochemical reaction, and the consumption flow is recorded as The difference between the two (V 差值 ) is the volume of gas discharged from the tail pipe; in, The hydrogen side Substituting the above formula into the second equation, we can get the amount of water discharged in the tail pipe on the hydrogen side, which is expressed as m 阳极尾管水 ; The oxygen side Substituting the above formula into the second equation, we can get the amount of water discharged in the tail pipe on the oxygen side, which is expressed as m 阳极尾管水 . m 阳极排水 =m 气水分离器1 +m 阳极尾管水 ; m 阴极排水 =m 气水分离器2 +m 阴极尾管水 ; Among them, the data of the gas-water separator in the anode exhaust assembly is recorded as m 气水分离器1 , the data of the gas-water separator in the cathode exhaust assembly is recorded as m 气水分离器2 .

10. The fuel cell water balance test method according to claim 5, characterized in that: If anode humidifying water + cathode humidifying water + produced water = anode drainage + cathode drainage, it indicates that the water balance is reached; if anode humidifying water + cathode humidifying water + produced water > anode drainage + cathode drainage, it indicates that the fuel cell stack is flooded; if anode humidifying water + cathode humidifying water + produced water < anode drainage + cathode drainage, it indicates that the inside of the fuel cell stack is too dry.

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