Fuel cell water balance test system and method

Abstract

The application discloses a fuel cell water balance test system, which comprises an anode gas inlet assembly, a cathode gas inlet assembly, a fuel cell, a current sensor, an anode gas outlet assembly and a cathode gas outlet assembly. The anode gas inlet assembly and the cathode gas inlet assembly are connected with the anode and the cathode of the fuel cell respectively, and the anode gas outlet assembly and the cathode gas outlet assembly are connected with the fuel cell. The current sensor is connected with the fuel cell. The application further discloses a fuel cell water balance test method. The anode humidification water amount and the cathode humidification water amount of the gas inlet end are calculated according to the gas flow, the gas pressure and the gas dew point of the gas inlet end. The water amount generated by the fuel cell reaction is calculated according to the current measured by the current sensor. The anode drainage amount and the cathode drainage amount of the gas outlet end are calculated according to the gas flow, the gas pressure and the gas dew point of the gas outlet end. The water balance inside the fuel cell is determined according to the above data. The application has the beneficial effect of high water balance test precision.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of hydrogen fuel cell testing, and in particular to a fuel cell water balance testing system and method. BACKGROUND

[0002] A hydrogen fuel cell is a device that converts chemical energy into electrical energy using hydrogen and oxygen as raw fuel. Fuel cells have high energy conversion efficiency, zero pollution, and other characteristics, and therefore have broad application prospects. A fuel cell testing system mainly provides a stable, safe, and convenient testing platform for fuel cells. The management of water content inside the fuel cell has an important influence on the performance of the cell. Insufficient water content can cause the electrolyte membrane to dry out, increase the internal resistance of the cell, and reduce the output voltage; while excessive water content can hinder the diffusion of fuel gas, also causing the output voltage to drop. Therefore, fuel cell water balance testing is an important means of evaluating cell performance and optimizing cell structure.

[0003] CN117855529A discloses a fuel cell water balance testing system, which includes a stack, humidity sensors, temperature sensors, and a control computing element. Humidity sensors and temperature sensors are arranged at the inlet and outlet of the stack, respectively. The retained water content inside the stack is determined according to the calculated net inflow water content of the stack, so that the control computing element controls and adjusts the humidity of the inlet gas by controlling the humidification tank, and finally maintains the water content balance inside the stack. However, this water balance testing system ignores the working pressure of the normal stack, and the saturation moisture content under different pressures is different. Moreover, the system ignores the condensation of high-humidity gas, does not perform insulation and heating treatment, and the high-precision dew point sensor is not accurate in measurement under high humidity or even liquid water. In addition, the measurement of the electronic scale under different pressures is also not accurate.

[0004] CN110429306A discloses a fuel cell water balance testing device and method, which provides a fuel cell water balance testing device and method to maintain the water balance in a proton exchange membrane fuel cell and improve the performance and life of the cell. The device includes an anode outlet dew point measurement device, a cathode outlet dew point measurement device, an anode heating device, a cathode heating device, and a current measurement device. The anode heating device is used to heat the gas duct 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 duct 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 measurement device, and a cathode inlet dew point measurement device. This invention ignores the measurement of anode and cathode flow and pressure at the stack inlet, and the gas saturation moisture content under different flow and pressure is completely different. In addition, the efficiency of direct heating of liquid water to complete vaporization is not evaluated, and there is a problem of inaccurate measurement caused by incomplete vaporization of part of the liquid water.

[0005] The existing fuel cell water balance test system and method cannot fully meet the requirements, the measurement data is not comprehensive and accurate, there are large errors and low precision problems, research finds that the following problems exist:

[0006] On the one hand, the fuel cell water balance test system is incomplete, and the measurement of gas flow and the measurement of stack inlet pressure are ignored, so that the actual water content at the stack inlet cannot be calculated, and the basic working pressure range of the fuel cell stack is ignored, and the test data is not the data during the actual stack operation.

[0007] On the other hand, the liquid water measurement of the fuel cell water balance test is not accurate, some existing technologies ignore the measurement of liquid water, and another part of the existing technologies do not evaluate the efficiency of directly heating and completely gasifying the liquid water, and there is a problem of inaccurate measurement caused by incomplete gasification of part of the liquid water.

[0008] The information disclosed in this part of the background is only intended to increase the understanding of the overall background of the present application, and should not be regarded as acknowledging or implying in any form that the information has been constructed as prior art known to those skilled in the art. SUMMARY

[0009] The technical problem to be solved by the present application is how to solve the problem of inaccurate measurement data, large errors and low precision in the prior art.

[0010] The present application solves the above technical problems by the following technical means:

[0011] 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 gas outlet assembly and a cathode gas outlet assembly, the anode gas inlet assembly and the cathode gas inlet assembly are connected with the anode and the cathode of the fuel cell respectively, and the anode gas outlet assembly and the cathode gas outlet assembly are connected with the fuel cell; the current sensor is connected with the fuel cell;

[0012] The anode gas inlet assembly and the cathode gas inlet assembly each comprise a dry gas path and a wet gas path, the dry gas path is connected with a first mass flow controller, a first dew point sensor and a first pressure sensor in sequence, and the wet gas path is connected with a second mass flow controller and a humidification module in sequence; the humidification module is connected with the wet gas path at the end;

[0013] The tail exhaust pipeline of the anode gas outlet assembly and the cathode gas outlet assembly is connected with a gas-water separator, a second dew point sensor and a third pressure sensor in sequence.

[0014] The application adds the sampling of the current sensor, the gas flow controller, the dew point sensor and the anode and cathode inlet and outlet stack pressure sensors in the fuel cell water balance test system, calculates the accurate gas water content of the stack inlet according to the flow, pressure and dew point value, measures the generated water amount through the current, and calculates the gas water content of the outlet through the flow, dew point and pressure. In the fuel cell operation process, the water sources mainly include the reaction generated water and the external humidification entered water; the water flow and change amount are measured to evaluate the water balance state of the fuel cell. The application simultaneously considers the three influencing factors of the flow, pressure and dew point, has high water balance test precision, simple structure, small volume, simple control logic, good stability, and is convenient for installation and later maintenance.

[0015] Preferably, the first gas control valve, the first mass flow controller, the first check valve, the heater, the first temperature sensor, the first dew point sensor, the second temperature sensor and the first pressure sensor are sequentially connected on the dry gas path pipeline.

[0016] Preferably, the third gas control valve, the second mass flow controller, the second check valve, the humidification module and the second gas control valve are sequentially connected on the wet gas path pipeline, and the tail end of the wet gas path pipeline is connected between the first check valve and the heater; the fuel gas is mixed in the dry gas path pipeline and the wet gas path pipeline and then enters the fuel cell.

[0017] Preferably, the tail exhaust pipeline of the anode exhaust assembly and the cathode exhaust assembly is sequentially connected with the gas-water separation device, the second dew point sensor, the third pressure sensor and the third temperature sensor, and the bottom of the gas-water separation device is further connected with the first exhaust pipeline, and the second pressure sensor and the electromagnetic valve are connected on the first exhaust pipeline.

[0018] The fuel cell water balance test method adopts the above fuel cell water balance test system and comprises the following steps.

[0019] S1: calculating the anode humidification water amount and the cathode humidification water amount of the gas inlet end according to the gas flow, gas pressure and gas dew point of the gas inlet end;

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

[0021] S3: calculating the anode drainage amount and the cathode drainage amount of the gas exhaust end according to the gas flow, gas pressure and gas dew point of the gas exhaust end;

[0022] According to the above data, the internal water balance state of the fuel cell is judged.

[0023] Preferably, in S1, the anode humidification water amount and the cathode humidification water amount are respectively obtained through Formula One.

[0024]

[0025] where V is obtained from the sum of the first mass flow controller 102 and the second mass flow controller valve;

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

[0027] A, B, C are constants of Antoine equation, depending on the type of gas, 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, 18 g / mol;

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

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

[0032]

[0033] where the current I is measured by the current sensor or the known current value;

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

[0035] Number of electrons transferred per mole of reactant n: for PEMFC, n = 2.

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

[0037] Preferably, in S3, first measured by the first mass flow controller and the second mass flow controller valve in the anode gas inlet assembly and the cathode gas inlet assembly are the total gas flow rates respectively The theoretical consumption flow rate of the fuel cell is calculated by Faraday's law and the theoretical calculation of the electrochemical reaction. The flow rate consumed is respectively recorded as The difference (V 差值 ) between the two is the amount of gas discharged by the tail exhaust pipeline;

[0038] where,

[0039]

[0040] The hydrogen side will be The hydrogen side tail exhaust pipe water discharge amount is obtained by bringing the above formula two into the formula two, and is recorded as m 阳极尾管水 ;

[0041] The oxygen side tail exhaust pipe water discharge amount is obtained by bringing the above formula two into the formula two, and is recorded as m The hydrogen side tail exhaust pipe water discharge amount is obtained by bringing the above formula two into the formula two, and is recorded 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] The data of the gas-water separator in the anode exhaust assembly is recorded as m 气水分离器1 , and the data of the gas-water separator in the cathode exhaust assembly is recorded as m 气水分离器2 .

[0045] Preferably, if the anode humidification water + the cathode humidification water + the generated water = the anode water discharge + the cathode water discharge, it indicates that the water balance state is reached; if the anode humidification water + the cathode humidification water + the generated water > the anode water discharge + the cathode water discharge, it indicates that the water inside the stack is flooded; and if the anode humidification water + the cathode humidification water + the generated water < the anode water discharge + the cathode water discharge, it indicates that the water inside the stack is too dry.

[0046] The present application has the following advantages:

[0047] The present application can accurately measure the fuel cell humidification water amount and the discharge water amount by arranging the dew point sensor, the temperature sensor and the pressure sensor at the inlet and outlet of the fuel cell, and can accurately calculate the fuel cell reaction generated water by arranging the current sensor at the positive and negative electrodes of the fuel cell; the water vapor separation device can effectively reduce the gas temperature and humidity after the fuel cell reaction, the present application simultaneously considers the three influencing factors of flow, pressure and dew point, has high water balance precision, solves the problem that the high-precision dew point sensor cannot be accurately measured in the high-humidity or liquid water condition, and solves the problem of poor test precision of most existing test benches.

[0048] The water vapor separation device of the present application increases the differential pressure type liquid level meter, and the liquid level height and the water vapor separation liquid storage pipe cross-sectional area are used to calculate the mass of the liquid water in real time, so that the liquid water can be collected and calculated in real time, and different working conditions of the normal operation of the fuel cell can be met, and the working pressure has no influence.

[0049] The present application increases the thermal insulation cotton and the heat tracing band in the tail exhaust pipeline to perform the thermal insulation and heat tracing treatment, and reduces the test error caused by the condensation of the tail exhaust gas.

[0050] The application has simple structure, small volume, simple control logic, good stability, and is convenient for installation and later maintenance. BRIEF DESCRIPTION OF DRAWINGS

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

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

[0053] Reference numerals in the drawings:

[0054] 100, anode gas inlet 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 gas inlet assembly;

[0056] 200, fuel cell;

[0057] 300, current sensor;

[0058] 400, anode gas outlet assembly; 401, water-gas separation device; 402, second dew point sensor; 403, third pressure sensor; 404, third temperature sensor; 405, second pressure sensor; 406, electromagnetic valve;

[0059] 600, cathode gas outlet assembly. DETAILED DESCRIPTION

[0060] To make the purpose, technical scheme and advantages of the embodiments of the application clearer, the technical scheme in the embodiments of the application will be described clearly and completely below in conjunction with the embodiments of the application. Obviously, the described embodiments are some of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.

[0061] Embodiment one:

[0062] As Figure 1 , Figure 2As shown, 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 connected to the anode and cathode of the fuel cell 200, respectively. The anode exhaust assembly 400 and the cathode exhaust assembly 600 are connected to the fuel cell 200. The anode intake assembly 100 and the cathode intake assembly 200 have the same composition and connection method, and the anode exhaust assembly 400 and the cathode exhaust assembly 600 have the same composition and connection method. The current sensor 300 is connected to the fuel cell 200 and is used to measure the amount of water produced by the fuel cell reaction based on the current magnitude.

[0063] This embodiment uses the anode intake assembly 100 and the anode exhaust assembly 400 for illustration.

[0064] like Figure 1 As shown, the anode intake assembly 100 includes a dry gas path pipe and a wet gas path pipe. The dry gas path pipe is sequentially connected to a first pneumatic control valve 101, a first mass flow controller 102, a first check 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 path pipe is sequentially connected to a third pneumatic control valve 109, a second mass flow control valve 110, a second check valve 111, a humidification module 112, and a second pneumatic control valve 113. The end of the wet gas path pipe is connected between the first check valve 103 and the heater 104. The dry and wet gas paths are mixed before entering the fuel cell 200.

[0065] The anode exhaust assembly 400 includes an exhaust gas venting pipe, on which a water-gas separator 401, a second dew point sensor 402, a third pressure sensor 403, and a third temperature sensor 404 are connected in sequence. The water-gas separator 401 is also connected to a first venting pipe, on which a second pressure sensor 405 and a solenoid valve 406 are connected.

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

[0067] During the operation of fuel cell 200, the water sources mainly include water generated in the reaction and water introduced by external humidification. The water balance of fuel cell 200 is assessed by measuring the flow and changes of this water. By detecting the water content entering the fuel cell (anode humidification water, cathode humidification water), the amount of water in the water-gas separator, and the amount of water carried away by the exhaust gas (anode drainage + cathode drainage), the amount of water remaining in fuel cell 200 (generated water) is calculated; thus, the water balance state within fuel cell 200 is determined.

[0068] The judging formula of water balance is whether (anode humidification water + cathode humidification water + generated water) is equal to (anode drainage + cathode drainage); if anode humidification water + cathode humidification water + generated water = anode drainage + cathode drainage, it indicates that the fuel cell reaches the water balance state; if anode humidification water + cathode humidification water + generated water > anode drainage + cathode drainage, it indicates that the fuel cell is flooded; if anode humidification water + cathode humidification water + generated water < anode drainage + cathode drainage, it indicates that the fuel cell is over-dry.

[0069] Anode drainage = water in the water-gas separation device in the anode exhaust assembly + drainage in the tail exhaust pipeline;

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

[0071] The embodiment is described by the anode. In the fuel cell test process, the fuel gas enters the humidification module 112 along the humidity path for humidification, and then the humidified gas enters the heater 104 for heating. When the gas temperature and dew point temperature reach the target value, the fuel cell 200 performs normal polarization test. At this time, the first dew point sensor 106, the first pressure sensor 107 and the second temperature sensor 108 are arranged at the inlet of the fuel cell, and the water content in the gas can be calculated according to the gas flow, dew point and pressure. The fuel gas reacts through the fuel cell 200 and is discharged from the outlet. The tail exhaust gas is separated by the water-gas separation device 401, and the liquid flows into the bottom of the water-gas separation device. The differential pressure liquid level meter 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 pressure difference. The gas separated by the water-gas separation device is discharged through the tail exhaust pipeline. The second dew point sensor 402, the third pressure sensor 403 and the third temperature sensor 404 are arranged between the water-gas separation device 401 and the tail exhaust pipeline, and the water content in the tail exhaust gas can be calculated according to the gas flow, dew point and pressure.

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

[0073] S1: calculating the water content of the inlet gas according to the gas flow, gas pressure and gas dew point of the inlet gas;

[0074] 1. Calculate the saturated water vapor pressure

[0075] Saturated water vapor pressure P w The gas dew point temperature T d The Antoine equation is usually used:

[0076]

[0077] where A, B, C are constants of the Antoine equation, depending on the type of gas (for water vapor, the constants can be found in tables)

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

[0079] 2. Calculate the water vapor partial pressure

[0080] The water vapor partial pressure P vap can be calculated from the relative humidity φ and the saturated water vapor pressure P w sat:

[0081] P vap = φ × P w

[0082] In fuel cell tests, it is usually assumed that the gas is completely saturated, i.e. the relative humidity φ = 1, so that

[0083] P vap = P w

[0084] 3. Calculate the water vapor mole fraction

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

[0086]

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

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

[0089]

[0090] where 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, with 18 g / mol.

[0094] Note: Gas flow is the actual flow, but the flow V measured by the mass flow controller is at standard conditions (standard pressure is usually 1 atm (101.325 kPa)), so the actual Also converted according to the gas state equation, as follows:

[0095]

[0096] The formula is:

[0097]

[0098] After simplification:

[0099]

[0100] Again, the into the above formula, finally:

[0101]

[0102] Where V is the sum of the first mass flow controller 102 and the second mass flow control valve 110, T d Measured by the first dew point sensor, A, B, C, R, Mwater, are known values. P total Measured by the first pressure sensor 107. Through the above formula, the water content of the gas can be calculated according to the gas flow, gas pressure, and gas dew point.

[0103] It should be noted that the dew point under different pressure is not the same, and the corresponding water content is different. When the pressure of the gas increases, the distance between the gas molecules becomes smaller, and the 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 the pressure. When the pressure of the gas decreases, the distance between the gas molecules becomes larger, and the water vapor molecules are more likely to escape from the liquid water to form gaseous water. Therefore, the dew point temperature of the gas will decrease with the decrease of the 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 temperature is the same, the water content of the gas will be different. This is because the change of pressure will affect the saturation water vapor pressure of the gas. Because the water content of the gas cannot be directly calculated by the pressure and flow rate of the gas. 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 the information of the dew point temperature, we cannot determine the partial pressure of water vapor in the gas, so we cannot calculate the water content of the gas. Therefore, the water content under the joint action of gas flow, gas pressure and gas dew point should be considered as a whole, which is accurate.

[0104] The anode humidification water and the cathode humidification water are calculated by the above formula one respectively, and are denoted as m 阳极增湿水 and m 阴极增湿水 respectively. The water in the water-gas separation device is directly read by the water-gas separation device, and 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 reaction of the fuel cell can be calculated according to the current size. The calculation formula is as follows:

[0106] 1. Electrochemical reaction equation

[0107] The electrochemical reaction equation of PEMFC is:

[0108] Anode reaction: H2→ 2H + + 2e -

[0109] Cathode reaction:

[0110] 2. Calculation formula

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

[0112]

[0113] where 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 water generation

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

[0119]

[0120] where, 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 or know the current value through the current sensor 300.

[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] Assuming I = 10 A, 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 into volume or mass, the molar mass and density of water can be used:

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

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

[0133] Rate of change in the mass of generated water:

[0134]

[0135] Rate of change in volume of water produced:

[0136]

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

[0138] S3: Based on the calculated drainage volume in the tailpipe

[0139] The drainage volume in the tailpipe is still calculated using Formula 1. However, since directly measuring the flow rate in the tailpipe is inaccurate, the first mass flow controller 102 and the second mass flow control valve 110 measure the total air flow rate. The theoretical flow rate consumption of a fuel cell can be calculated using Faraday's law and the theory of electrochemical reactions. The difference between the two (V) 差值H2 V 差值O2 () refers to the amount of gas discharged from the tailpipe.

[0140]

[0141] Hydrogen side Substituting into Formula 2 above, we obtain the water discharge volume in the tailpipe on the hydrogen side, denoted as m. 阳极尾管水 ;

[0142] oxygen side Substituting into Formula 2 above, the drainage volume in the oxygen-side tailpipe is obtained, 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 water balance is determined by the formula: whether (anode humidification water + cathode humidification water + generated water) equals (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 This indicates that the fuel cell has reached a 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 the fuel cell is flooded internally;

[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 fuel cell is over-dried internally.

[0149] In the present embodiment, the sampling of the current sensor, the gas flow controller, the dew point sensor and the anode and cathode inlet and outlet stack pressure sensors is increased in the fuel cell water balance test system, and the inlet and outlet stack pipelines are subjected to heat preservation and heating treatment. 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 accurate calculation of the gas water content at the inlet of the stack under different operating conditions of the normal operation of the stack according to the flow, pressure and dew point value. A water-gas separation device is added before the outlet of the stack and the dew point sensor to ensure the collection of liquid water at the outlet of the stack, reduce the outlet humidity, and measure the dew point value of the low humidity gas through the dew point sensor. After the water-gas separation device, a pressure sensor is added at the dew point measurement point, which can calculate the gas water content at the outlet through the flow, dew point and pressure. The problem of poor test accuracy of the water balance test of most existing test benches is solved, and the normal operation of the fuel cell under different operating conditions is met, which is not affected by the working pressure, and the universality of the test bench is improved.

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

[0151] In the present embodiment, the fuel cell outlet pipeline is provided with heat preservation cotton and a heating band, and the fuel cell outlet gas is subjected to heat preservation and heating treatment to 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 application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced by equivalents; 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 embodiments of the present application.

Claims

1. A method of testing a fuel cell water balance, characterized by, The fuel cell includes an anode gas inlet assembly, a cathode gas inlet assembly, a fuel cell, a current sensor, an anode gas outlet assembly, a cathode gas outlet assembly, the anode gas inlet assembly and the cathode gas inlet assembly are connected with the anode and the cathode of the fuel cell respectively, and the anode gas outlet assembly and the cathode gas outlet assembly are connected with the fuel cell; the current sensor is connected with the fuel cell; The anode gas inlet assembly and the cathode gas inlet assembly each include a dry gas path and a wet gas path, the dry gas path is sequentially connected with a first mass flow controller, a first dew point sensor and a first pressure sensor, and the wet gas path is sequentially connected with a second mass flow controller and a humidification module; the humidification module is connected with the wet gas path at the end; The tail exhaust pipeline of the anode gas outlet assembly and the cathode gas outlet assembly is sequentially connected with a gas-water separation device, a second dew point sensor and a third pressure sensor; The fuel cell water balance test method includes the following steps: S1: calculating the anode humidification water amount and the cathode humidification water amount at the gas inlet end according to the gas flow, the gas pressure and the gas dew point at the gas inlet end; S2: calculating the water amount generated by the fuel cell reaction according to the current measured by the current sensor; S3: calculating the anode drainage amount and the cathode drainage amount at the gas outlet end according to the gas flow, the gas pressure and the gas dew point at the gas outlet end; judging the internal water balance of the fuel cell according to the above data; In S1, the anode humidification water amount and the cathode humidification water amount are obtained respectively through Formula One; (Formula One) V is obtained from the sum of the first mass flow controller 102 and the second mass flow controller valve; measured by the first dew point sensor; absolute temperature of the gas, A, B and C are constants of the Antoine equation, which depend on the type of gas and are obtained by looking up a table; R is the universal gas constant, = 8.314 ; is the molar mass of water, taken as 18 g / mol; measured by the first pressure sensor; In S3, the total gas flow is measured by the first mass flow controller and the second mass flow controller in the anode gas inlet assembly and the cathode gas inlet assembly, respectively , , the theoretical consumption flow of the fuel cell is calculated by Faraday's law and the theoretical calculation of the electrochemical reaction, and the consumption flow is recorded as , , and the difference between the two (Q ) is the exhaust pipe exhaust gas wherein ; ; (Equation Two) The hydrogen side , into equation two above to obtain the discharge capacity of the exhaust pipe on the hydrogen side, denoted as ; I is the current value measured by the current sensor or known, and F is the Faraday constant. The oxygen side , into the above formula two to get oxygen side of the tail exhaust pipe in the displacement, recorded as ; ； ； Wherein, the data of the gas-water separator in the anode exhaust assembly is recorded as , and the data of the gas-water separator in the cathode exhaust assembly is recorded as .

2. The fuel cell water balance test method of claim 1, wherein, The dry gas path pipeline is sequentially connected with a first gas control valve, a first mass flow controller, a first check 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 method of claim 2, wherein, The wet gas path pipeline is sequentially connected with a third gas control valve, a second mass flow controller valve, a second check valve, a humidification module and a second gas control valve, wherein the end of the wet gas path pipeline is connected between the first check valve and the heater; the fuel gas is mixed in the dry gas path pipeline and the wet gas path pipeline and then enters the fuel cell.

4. The fuel cell water balance test method of claim 2, wherein, The tail exhaust pipeline of the anode gas outlet assembly and the cathode gas outlet assembly is sequentially connected with a gas-water separation device, a second dew point sensor, a third pressure sensor and a third temperature sensor, wherein the bottom of the gas-water separation device is further connected with a first exhaust pipeline, and the first exhaust pipeline is connected with a second pressure sensor and an electromagnetic valve.

5. The fuel cell water balance test method according to claim 1, wherein, In S2, the calculation formula for calculating the water amount generated by the fuel cell reaction according to the current measured by the current sensor is: wherein the current I is measured by the current sensor or a known current value; Faraday constant F: F = 96485 C / mol Number of electrons transferred per mole of reactant n: for PEMFC, n = 2.

6. The fuel cell water balance test method of claim 1, wherein, In S3, the anode drainage amount is the sum of the water in the water-gas separation device in the anode gas outlet assembly and the drainage amount in the tail exhaust pipeline; and the cathode drainage amount is the sum of the water in the water-gas separation device in the cathode gas outlet assembly and the drainage amount in the tail exhaust pipeline.

7. The fuel cell water balance test method of claim 1, wherein, If anode humidification water + cathode humidification water + generated water = anode drainage + cathode drainage, it indicates that the water balance is reached; if anode humidification water + cathode humidification water + generated water > anode drainage + cathode drainage, it indicates that the water inside the stack is flooded; if anode humidification water + cathode humidification water + generated water < anode drainage + cathode drainage, it indicates that the water inside the stack is too dry.

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