CN116093385A - Multi-point voltage-based fuel cell anode nitrogen concentration estimation method - Google Patents
Multi-point voltage-based fuel cell anode nitrogen concentration estimation method Download PDFInfo
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 title claims abstract description 222
- 229910052757 nitrogen Inorganic materials 0.000 title claims abstract description 109
- 239000000446 fuel Substances 0.000 title claims abstract description 58
- 238000000034 method Methods 0.000 title claims abstract description 31
- 239000007789 gas Substances 0.000 claims abstract description 85
- 238000012544 monitoring process Methods 0.000 claims abstract description 8
- 239000001257 hydrogen Substances 0.000 claims description 44
- 229910052739 hydrogen Inorganic materials 0.000 claims description 44
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 39
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 36
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 21
- 239000001301 oxygen Substances 0.000 claims description 21
- 229910052760 oxygen Inorganic materials 0.000 claims description 21
- 238000010926 purge Methods 0.000 claims description 19
- 230000032895 transmembrane transport Effects 0.000 claims description 14
- 150000002431 hydrogen Chemical class 0.000 claims description 8
- 238000009825 accumulation Methods 0.000 claims description 6
- 230000035699 permeability Effects 0.000 claims description 6
- 230000004913 activation Effects 0.000 claims description 3
- 238000006243 chemical reaction Methods 0.000 claims description 3
- 238000005370 electroosmosis Methods 0.000 claims description 3
- 229920006254 polymer film Polymers 0.000 claims description 3
- 239000000376 reactant Substances 0.000 claims description 3
- 238000001223 reverse osmosis Methods 0.000 claims description 3
- 230000035515 penetration Effects 0.000 claims 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 abstract 1
- 229910002804 graphite Inorganic materials 0.000 abstract 1
- 239000010439 graphite Substances 0.000 abstract 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 4
- 238000000746 purification Methods 0.000 description 3
- 238000005070 sampling Methods 0.000 description 3
- 230000005540 biological transmission Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 239000012466 permeate Substances 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000012528 membrane Substances 0.000 description 1
- 230000008092 positive effect Effects 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 238000006479 redox reaction Methods 0.000 description 1
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Abstract
The invention discloses a fuel cell anode nitrogen concentration estimation method based on multipoint voltage, which comprises the steps of firstly, respectively acquiring the voltage of a single cell at an anode inlet and an anode outlet based on a multipoint voltage monitoring method aiming at the characteristic of large active area of a commercial-size fuel cell, and taking the voltage as a feedback signal; then dividing the fuel cell into two half cells based on a discretization method, wherein an anode inlet half cell consists of an anode inlet cavity and a cathode outlet cavity; the anode outlet half cell consists of an anode outlet cavity and a cathode inlet cavity; and introducing a gas dynamic equation and a voltage equation to accurately solve the nitrogen concentration at the outlet of the anode. Aiming at the problem of uneven distribution of components in a commercial-size fuel cell, the scheme provides a nitrogen concentration estimation method of the commercial-size fuel cell, which is suitable for the commercial-size graphite plate fuel cell.
Description
Technical Field
The invention belongs to the field of fuel cell anode nitrogen concentration estimation, and particularly relates to a fuel cell anode nitrogen concentration estimation method based on multipoint voltage.
Background
The fuel cell converts chemical energy from hydrogen and oxygen supplied from a hydrogen supply and an air supply, respectively, to electrical energy, and then generates oxidation-reduction reactions. The hydrogen supply subsystem of a fuel cell system directly affects the efficiency of the system and the life of the stack. As nitrogen, water vapor and hydrogen are transported across the membrane during operation of the fuel cell, nitrogen on the cathode side diffuses from the cathode to the anode, resulting in a decrease in the anode hydrogen concentration. In practical systems, however, a hydrogen recycling scheme is employed for cost savings, which can lead to nitrogen accumulation on the anode side, resulting in reduced fuel cell performance.
The existing nitrogen gas estimation method is used for homogenizing the nitrogen gas concentration inside the fuel cell, and the problem of in-plane heterogeneity of the commercial size fuel cell is not considered, so that a novel nitrogen gas concentration estimation method is needed to accurately describe the nitrogen gas concentration of each single cell.
Disclosure of Invention
The invention provides a fuel cell anode nitrogen concentration estimation method based on multipoint voltage, which aims at the characteristics of a commercial-size fuel cell engine and provides an anode outlet position nitrogen concentration estimation method based on a multipoint voltage monitoring method, so that the problem of online observation of anode nitrogen concentration in the running process of the commercial-size fuel cell engine system is solved.
The invention is realized by adopting the following technical scheme: a fuel cell anode nitrogen concentration estimation method based on multipoint voltage comprises the following steps:
step A, a multipoint voltage monitoring method is adopted to obtain multipoint voltage data of the fuel cell;
step B, establishing a gas dynamic model and a gas transmembrane transport model based on the multipoint voltage data;
dividing an anode and a cathode of a fuel cell into two cavities respectively, wherein the two cavities comprise an anode inlet cavity, an anode outlet cavity, a cathode inlet cavity and a cathode outlet cavity, the anode inlet cavity and the cathode outlet cavity form a half cell, the anode outlet cavity and the cathode inlet cavity form a half cell, the two half cells are connected in parallel on a circuit, and are connected in series on a gas circuit; respectively constructing gas dynamic models of four cavities, and constructing a gas transmembrane transport model based on multipoint voltage data;
step C, constructing an exhaust model and a voltage model according to the gas dynamic model and the gas transmembrane transport model;
step D, solving the nitrogen concentration at the outlet of the anode:
(1) Calculating the nitrogen concentration in the anode cavity of the single-chip battery: firstly, respectively calculating the permeation nitrogen amount and permeation steam amount in two cavities of a cathode inlet cavity and a cathode outlet cavity, and the purging amount of nitrogen and steam; then calculating the current nitrogen amount in the anode flow channel based on the permeated nitrogen amount and the purging amount of the nitrogen, and calculating the current amounts of the nitrogen and the steam by integrating the accumulation rate and the purging rate per unit time and adding the integrated accumulation rate and the purging rate to the initial amount;
(2) And obtaining the nitrogen concentration of the anode outlet of each cell to obtain the weighted nitrogen concentration of the commercial-size fuel cell stack, thereby realizing the estimation of the nitrogen concentration.
7. The method for estimating the anode nitrogen concentration of a fuel cell based on a multipoint voltage according to claim 1, wherein: in the step B, the constructed gas dynamic model of the four cavities is as follows:
(1) Gas dynamic model of anode inlet chamber:
wherein ,is the hydrogen pressure in the anode inlet chamber, V an Is the volume of the anode, R is the ideal gas constant, T fc Is the temperature of the galvanic pile>Is the molar flow of hydrogen into the anode inlet chamber,/->Is the molar flow of hydrogen, i, from the anode inlet chamber to the anode outlet chamber 1 Is the current of half cell at anode inlet, F is Faraday constant, A is active area of cell, N is number of cells,/L>Is the molar flow of hydrogen permeated from the anode to the cathode in the anode inlet cavity;is the nitrogen pressure in the anode inlet chamber,/-)>Is the molar flow of nitrogen permeated from the cathode to the anode in the anode inlet chamber, +.>Is the nitrogen molar flow from the anode inlet cavity to the anode outlet cavity;Is the water vapor pressure in the anode inlet chamber,/-, in the anode inlet chamber>Is the molar flow of water vapor from anode to cathode in the anode inlet cavity,/i>Is the molar flow of water vapor from the anode inlet cavity to the anode outlet cavity; p (P) an,ch1 Is the gas pressure of the anode inlet chamber;
(2) Anode outlet chamber gas dynamic model:
wherein ,is the hydrogen pressure in the anode outlet cavity, +.>Is a discharge anodeHydrogen molar flow of i 2 Is the current of half-cell at the anode outlet, +.>Is the molar flow of hydrogen permeated from the anode to the cathode in the anode outlet cavity;Is the nitrogen pressure in the anode outlet cavity, +.>Is the molar flow of nitrogen permeated from the cathode to the anode in the anode outlet cavity, +.>Is the molar flow of the nitrogen discharged;Is the water vapor pressure in the anode outlet cavity,is the molar flow of water vapor from anode to cathode in the anode outlet cavity, +.>Is the molar flow of water vapor from the anode inlet cavity to the anode outlet cavity; p (P) an,ch2 Is the gas pressure of the anode outlet cavity;
(3) Gas dynamic model in cathode inlet chamber:
wherein ,is the oxygen pressure in the cathode inlet chamber, V ca Is the volume of the anode, ">Is the molar flow of oxygen into the cathode inlet chamber,/->Is the molar flow of oxygen from the cathode inlet chamber to the cathode outlet chamber;is the nitrogen pressure in the cathode inlet chamber,/-)>Is the molar flow of air into the cathode inlet chamber,is the nitrogen molar flow from the cathode inlet cavity to the cathode outlet cavity;Is the water vapor pressure in the cathode inlet chamber,/-, in the cathode inlet chamber>Is a cathode inlet cavity to a cathode outlet cavityWater vapor molar flow rate;Is the hydrogen pressure in the cathode inlet chamber,/-)>Is the molar flow of hydrogen from the cathode inlet chamber to the cathode outlet chamber; p (P) ca,ch3 Is the gas pressure of the cathode inlet chamber;
(4) Gas dynamic model in cathode outlet cavity:
wherein ,is the oxygen pressure in the cathode outlet cavity, +.>Is the molar flow of oxygen into and out of the reactor, < + >>Is the cathodeNitrogen pressure in the outlet cavity, +.>Is the molar flow of the nitrogen discharged;Is the water vapor pressure in the cathode outlet cavity,/->Is the molar flow rate of the discharged water vapor;Is the hydrogen pressure in the cathode outlet chamber,/-)>Is the molar flow of the discharged hydrogen; p (P) ca,ch4 Is the gas pressure of the cathode outlet chamber.
Further, in the step B, a gas transmembrane transport model established based on the multipoint voltage data is as follows:
wherein ,is the permeability coefficient of hydrogen, ">Is the permeability coefficient of nitrogen, c ca Is the cathode water concentration, c an,ch1 Is the water concentration of the anode inlet cavity, c an,ch2 Is the water concentration of the anode outlet cavity, n d Is the electroosmosis resistance coefficient, D w Is the reverse osmosis coefficient.
Further, in the step C, the constructed exhaust model is as follows:
purge flow of gasCan be combined with anode in the outlet cavityGas pressure (P) an,ch2 ) And the gas pressure (P) outside thereof an,out ) The difference between them is compared, C is the purge gain value, n an Is the total amount of gas in the anode:
Further, in the step C, the constructed voltage model is as follows:
wherein ,Vfc1 and Vfc2 Is the voltage at the anode inlet and anode outlet of a fuel cell obtained by using multiple points of voltage, a 0 Is the gas pressure parameter, P sat Is the pressure of the air at the point of the air, andThe oxygen concentration in the chamber 3 and in the chamber 4, respectively, < >>Is the open circuit voltage, v, calculated from Nernst's equation act Is the loss of activation voltage, v ohm Ohmic voltage loss due to the resistance of the polymer film to the cells, v conc Is the concentration voltage loss caused by the concentration drop of the reactant during the reaction.
Further, in the step D, it is assumed that the partial pressure of nitrogen in the anode outlet cavity of the first cell isThe partial pressure of nitrogen in the anode outlet chamber 2 of the j-th cell is +.>Then there are:
Compared with the prior art, the invention has the advantages and positive effects that:
according to the scheme, the commercial-size fuel single cell is divided into four cavities, the gas concentration changes in the cavities are calculated respectively, the expression of the dynamic relationship between the nitrogen concentration and the voltage is established, the nitrogen concentration at the corresponding position is represented by the multi-point voltage data, the nitrogen concentration at the anode outlet position of the commercial-size fuel cell is estimated more accurately, the problems of stack performance reduction and the like caused by inaccurate estimation are avoided, the nitrogen concentration at the outlet is used as a control variable, more accurate gas control can be realized, and further the purification of the anode in the fuel cell is helped to be controlled accurately.
Drawings
FIG. 1 is a schematic diagram of a multi-point voltage sampling in accordance with an embodiment of the present invention;
FIG. 2 is a model diagram of an embodiment of the present invention;
FIG. 3 is a flow chart of nitrogen concentration estimation according to an embodiment of the present invention;
fig. 4 is a control flow chart in an embodiment of the present invention.
Detailed Description
In order that the above objects, features and advantages of the invention will be more readily understood, a further description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced otherwise than as described herein, and thus the present invention is not limited to the specific embodiments disclosed below, in which commercial dimensions refer to active area dimensions of commercial fuel cells, as opposed to small-scale fuel cells for laboratory use.
In order to achieve the above object, the present embodiment proposes a fuel cell anode nitrogen concentration estimation method based on a multipoint voltage, the basic principle of which is as follows:
a multi-point voltage monitoring method is first implemented on a commercial-size fuel cell to obtain the voltages at the cell anode inlet and anode outlet, respectively. And establishing an anode two-cavity gas dynamic model and a gas transmembrane transport model. And establishing a voltage model according to the multi-point voltage data, and respectively calculating the nitrogen partial pressure and the nitrogen concentration of the two cavities. According to the invention, by combining the acquired voltage information of a plurality of positions with the information of the fuel cell anode inlet flow, pressure, relative humidity, fuel cell temperature, current and the like provided by the fuel cell test bench, the model is built, and the dynamic relationship between the nitrogen partial pressure and the voltage can be built by building the model, so that the nitrogen concentration of the anode outlet of each cell is acquired, and the weighted nitrogen concentration of the commercial-size fuel cell stack is obtained.
As shown in fig. 3, the method specifically comprises the following steps:
step A, obtaining multipoint voltage data of a commercial-size fuel cell based on a multipoint voltage monitoring method;
step B, establishing a gas dynamic model and a gas transmembrane transport model based on the multipoint voltage data;
step C, constructing an exhaust model and a voltage model according to the gas dynamic model and the gas transmembrane transport model;
and D, solving the nitrogen concentration at the outlet of the anode.
In step S1, a multi-point voltage monitoring method for a commercial-size fuel cell as shown in fig. 1 is first established, that is, voltage data is monitored at different positions of the cell, and in this embodiment, an anode inlet sampling point and an anode outlet sampling point are taken as examples, and specific multi-point voltage acquisition points are arbitrary.
In step S2, as shown in fig. 2, the anode and the cathode of the fuel cell are respectively divided into two cavities, and the two divided cavities are connected in series on the gas path and connected in parallel on the circuit, so that the fuel cell includes four cavities, namely, an anode inlet cavity 1, an anode outlet cavity 2, a cathode inlet cavity 3 and a cathode outlet cavity 4. Hydrogen firstly passes through the anode inlet cavity 1, reacts in the anode inlet cavity 1 and then enters the anode outlet cavity 2; the air passes through the cathode inlet cavity 3, reacts in the cathode inlet cavity 3 and then enters the cathode outlet cavity 4. The anode inlet cavity 1 and the cathode outlet cavity 4 form a half cell, the anode outlet cavity 2 and the cathode inlet cavity 3 form a half cell, and the voltage of the two half cells is obtained by a multipoint voltage monitoring method.
Considering that the two half batteries are connected in parallel on a circuit and connected in series on a gas circuit, a gas dynamic model of four cavities is constructed:
1) The gas dynamic model in the cavity 1 is as follows:
is the hydrogen pressure in the chamber 1, V an Is the volume of the anode, R is the ideal gas constant, T fc Is the temperature of the galvanic pile>Is the molar flow of hydrogen into the chamber 1, < >>Is the molar flow rate of hydrogen, i, from chamber 1 to chamber 2 1 Is the current of half cell at anode inlet, F is Faraday constant, A is active area of cell, N is number of cells,/L>Is the molar flow of hydrogen in the chamber 1 that permeates from the anode to the cathode.
Is the nitrogen pressure in the chamber 1, +.>Is the molar flow of nitrogen permeated from the cathode to the anode in the chamber 1,/the cathode is>Is the molar flow of nitrogen from chamber 1 to chamber 2.
Is the water vapor pressure in the cavity 1, < >>Is the molar flow of water vapor in the cavity 1 from anode to cathode, +.>Is the molar flow of water vapor from chamber 1 to chamber 2.
P an,ch1 Is the gas pressure of the chamber 1.
2) The gas dynamic model in the cavity 2 is as follows:
is the hydrogen pressure in the chamber 2, +.>Is the molar flow rate of hydrogen out of the anode, i 2 Is the current of half-cell at the anode outlet, +.>Is the molar flow of hydrogen in the chamber 2 that permeates from the anode to the cathode.
Is the nitrogen pressure in the chamber 2, +.>Is the molar flow of nitrogen permeated from the cathode to the anode in the chamber 2,/the cathode is>Is the molar flow of nitrogen that is discharged.
Is the water vapor pressure in the cavity 2, < >>Is the molar flow of water vapor in the cavity 2 from anode to cathode,/i>Is the molar flow of water vapor from chamber 1 to chamber 2.
P an,ch2 Is the gas pressure of the chamber 2.
3) The gas dynamic model in the cavity 3 is as follows:
is the oxygen pressure in the chamber 3, V ca Is the volume of the anode, ">Is the molar flow of oxygen into the chamber 3, < >>Is the molar flow of oxygen from chamber 3 to chamber 4.
Is the nitrogen pressure in the chamber 3, +.>Is the molar flow of air into the cavity 3, < >>Is the molar flow of nitrogen from chamber 3 to chamber 4.
Is the water vapor pressure in the cavity 3, < >>Is the molar flow of water vapor from chamber 3 to chamber 4. />
P ca,ch3 Is the gas pressure of the chamber 3.
4) The gas dynamic model in the cavity 4 is as follows:
Is the water vapor pressure in the cavity 4, < >>Is the molar flow rate of the discharged water vapor.
P ca,ch4 Is the gas pressure of the chamber 4.
Step S3: and establishing a gas transmembrane transmission model based on the multipoint voltage data.
Is the permeability coefficient of hydrogen, ">Is the permeability coefficient of nitrogen, c ca Is the cathode water concentration, c an,ch1 Is the water concentration of the anode cavity 1, c an,ch2 Is the water concentration, n, of the anode cavity 2 d Is the electroosmosis resistance coefficient, D w Is the reverse osmosis coefficient.
Step S4: according to the built gas dynamic model and the built gas transmembrane transport model, building an exhaust model;
purge flow of gasCan be matched with the gas pressure (P) in the anode outlet cavity 2 an,ch2 ) And the gas pressure (P) outside thereof an,out ) The difference between them is compared, C is the purge gain value, n an Is the total amount of gas in the anode.
Step S5: and building a voltage model according to the built gas dynamic model and the built gas transmembrane transmission model.
For this purpose, it is necessary to establish the relationship between the internal pressure, flow rate, temperature, current and voltage of the fuel cell, and the like, and the relationship between the oxygen partial pressure, the hydrogen partial pressure, the cell temperature, the oxygen concentration, the current and voltage is revealed:
wherein Vfc1 and Vfc2 Is the voltage at the anode inlet and anode outlet of a fuel cell obtained by using multiple points of voltage, a 0 Is the gas pressure parameter, P sat Is the pressure of the air at the point of the air, andThe oxygen concentration in the cavity 3 and the cavity 4 respectively;Is the open circuit voltage, v, calculated from Nernst's equation act Is the loss of activation voltage, v ohm Ohmic voltage loss due to the resistance of the polymer film to the cells, v conc Is the concentration voltage loss caused by the concentration drop of the reactant during the reaction.
Step S6: calculate the nitrogen concentration in the anode outlet chamber 2:
according to the gas dynamic model, the gas transmembrane transport model and the voltage model, the gas parameters in the model are provided by parameter fitting or a bench. According to the collected multipoint voltage data, the nitrogen concentration at the downstream of the anode is calculated according to the following specific principle:
firstly, the amount of permeated nitrogen and the amount of permeated steam in two cavities of the cathode are calculated respectively, and the purging amounts of the nitrogen and the steam are calculated. The current amount of nitrogen in the anode flow channel is then calculated based on the amount of permeated nitrogen and the purge amount of nitrogen. The current amounts of nitrogen and steam were calculated by integrating the accumulation rate and purge rate per unit time and adding the initial amounts using the gas dynamic model, the gas transmembrane transport model, and the voltage model described above. By the method, the nitrogen concentration at the outlet position of the anode can be estimated more accurately, the problem of inaccurate estimation of the nitrogen concentration in the fuel cell with commercial size is avoided, possible serious faults of the fuel cell are avoided, and the estimation accuracy of the nitrogen concentration is effectively improved.
Step S7: the nitrogen concentration at the anode outlet of each cell was obtained to obtain a weighted nitrogen concentration for a commercial size fuel cell stack.
Assuming that the partial pressure of nitrogen in the anode outlet cavity 2 of the first cell isThe partial pressure of nitrogen in the anode outlet chamber 2 of the j-th cell is +.>
Determining a weighted value of anode outlet nitrogen concentration for a commercial fuel cell stackWhether or not threshold X is reached, when->And when the hydrogen discharge valve is started, the opening frequency of the hydrogen discharge valve is increased by 25%, and the threshold X is obtained through calibration.
The multipoint voltage obtained by the invention is used as the feedback quantity of the fuel cell gas purification, thereby helping to accurately control the purification of the anode in the fuel cell and improving the hydrogen utilization rate, and the specific control process is shown in figure 4.
The present invention is not limited to the above-mentioned embodiments, and any equivalent embodiments which can be changed or modified by the technical content disclosed above can be applied to other fields, but any simple modification, equivalent changes and modification made to the above-mentioned embodiments according to the technical substance of the present invention without departing from the technical content of the present invention still belong to the protection scope of the technical solution of the present invention.
Claims (6)
1. A fuel cell anode nitrogen concentration estimation method based on a multi-point voltage, comprising the steps of:
step A, a multipoint voltage monitoring method is adopted to obtain multipoint voltage data of the fuel cell;
step B, establishing a gas dynamic model and a gas transmembrane transport model based on the multipoint voltage data;
dividing an anode and a cathode of a fuel cell into two cavities respectively, wherein the two cavities comprise an anode inlet cavity, an anode outlet cavity, a cathode inlet cavity and a cathode outlet cavity, the anode inlet cavity and the cathode outlet cavity form a half cell, the anode outlet cavity and the cathode inlet cavity form a half cell, the two half cells are connected in parallel on a circuit, and are connected in series on a gas circuit; respectively constructing gas dynamic models of four cavities, and constructing a gas transmembrane transport model based on multipoint voltage data;
step C, constructing an exhaust model and a voltage model according to the gas dynamic model and the gas transmembrane transport model;
step D, solving the nitrogen concentration at the outlet of the anode:
(1) Calculating the nitrogen concentration in the anode cavity of the single-chip battery: firstly, respectively calculating the permeation nitrogen amount and permeation steam amount in two cavities of a cathode inlet cavity and a cathode outlet cavity, and the purging amount of nitrogen and steam; then calculating the current nitrogen amount in the anode flow channel based on the permeated nitrogen amount and the purging amount of the nitrogen, and calculating the current amounts of the nitrogen and the steam by integrating the accumulation rate and the purging rate per unit time and adding the integrated accumulation rate and the purging rate to the initial amount;
(2) And obtaining the nitrogen concentration of the anode outlet of each cell to obtain the weighted nitrogen concentration of the commercial-size fuel cell stack, thereby realizing the estimation of the nitrogen concentration.
2. The method for estimating the anode nitrogen concentration of a fuel cell based on a multipoint voltage according to claim 1, wherein: in the step B, the constructed gas dynamic model of the four cavities is as follows:
(1) Gas dynamic model of anode inlet chamber:
wherein ,is the hydrogen pressure in the anode inlet chamber, V an Is the volume of the anode, R is the ideal gas constant, T fc Is the temperature of the galvanic pile>Is the molar flow of hydrogen into the anode inlet chamber,/->Is the molar flow of hydrogen, i, from the anode inlet chamber to the anode outlet chamber 1 Is the current of half cell at anode inlet, F is Faraday constant, A is active area of cell, N is number of cells,/L>Is anode penetration into the anode inlet cavityHydrogen molar flow of the cathode;is the nitrogen pressure in the anode inlet chamber,/-)>Is the molar flow of nitrogen permeated from the cathode to the anode in the anode inlet chamber, +.>Is the nitrogen molar flow from the anode inlet cavity to the anode outlet cavity;Is the water vapor pressure in the anode inlet chamber,/-, in the anode inlet chamber>Is the molar flow of water vapor from anode to cathode in the anode inlet cavity,/i>Is the molar flow of water vapor from the anode inlet cavity to the anode outlet cavity; p (P) an,ch1 Is the gas pressure of the anode inlet chamber;
(2) Anode outlet chamber gas dynamic model:
wherein ,is the hydrogen pressure in the anode outlet cavity, +.>Is the molar flow rate of hydrogen out of the anode, i 2 Is the current of half-cell at the anode outlet, +.>Is the molar flow of hydrogen permeated from the anode to the cathode in the anode outlet cavity;is the nitrogen pressure in the anode outlet cavity, +.>Is the molar flow of nitrogen permeated from the cathode to the anode in the anode outlet cavity, +.>Is the molar flow of the nitrogen discharged;Is the water vapor pressure in the anode outlet cavity,/->Is the molar flow of water vapor from anode to cathode in the anode outlet cavity, +.>Is the molar flow of water vapor from the anode inlet cavity to the anode outlet cavity; p (P) an,ch2 Is the gas pressure of the anode outlet cavity;
(3) Gas dynamic model in cathode inlet chamber:
wherein ,is the oxygen pressure in the cathode inlet chamber, V ca Is the volume of the anode, ">Is the molar flow of oxygen into the cathode inlet chamber,/->Is the molar flow of oxygen from the cathode inlet chamber to the cathode outlet chamber;Is the nitrogen pressure in the cathode inlet chamber,/-)>Is the molar flow of air into the cathode inlet chamber,/->Is the nitrogen molar flow from the cathode inlet cavity to the cathode outlet cavity;Is the water vapor pressure in the cathode inlet chamber,is the molar flow of water vapor from the cathode inlet cavity to the cathode outlet cavity;Is the hydrogen pressure in the cathode inlet chamber,/-)>Is the molar flow of hydrogen from the cathode inlet chamber to the cathode outlet chamber; p (P) ca,ch3 Is the gas pressure of the cathode inlet chamber;
(4) Gas dynamic model in cathode outlet cavity:
wherein ,is the oxygen pressure in the cathode outlet cavity, +.>Is the molar flow of oxygen into the exhaust,is the nitrogen pressure in the cathode outlet chamber, +.>Is the molar flow of the nitrogen discharged;Is the water vapor pressure in the cathode outlet cavity,/->Is the molar flow rate of the discharged water vapor;Is the hydrogen pressure in the cathode outlet chamber,/-)>Is the molar flow of the discharged hydrogen; p (P) ca,ch4 Is the cathode outletGas pressure of the chamber.
3. The method for estimating the anode nitrogen concentration of a fuel cell based on a multipoint voltage according to claim 2, wherein: in the step B, a gas transmembrane transport model established based on the multipoint voltage data is as follows:
wherein ,is the permeability coefficient of hydrogen, ">Is the permeability coefficient of nitrogen, c ca Is the cathode water concentration, c an,ch1 Is the water concentration of the anode inlet cavity, c an,ch2 Is the water concentration of the anode outlet cavity, n d Is the electroosmosis resistance coefficient, D w Is the reverse osmosis coefficient.
4. A fuel cell anode nitrogen concentration estimation method based on a multipoint voltage according to claim 3, wherein: in the step C, the constructed exhaust model is as follows:
5. The method for estimating anode nitrogen concentration of fuel cell based on multipoint voltage according to claim 4, wherein: in the step C, the constructed voltage model is as follows:
wherein ,Vfc1 and Vfc2 Is the voltage at the anode inlet and anode outlet of a fuel cell obtained by using multiple points of voltage, a 0 Is the gas pressure parameter, P sat Is the pressure of the air at the point of the air, andThe oxygen concentration in the chamber 3 and in the chamber 4, respectively, < >>Is the open circuit voltage, v, calculated from Nernst's equation act Is the loss of activation voltage, v ohm Ohmic voltage loss due to the resistance of the polymer film to the cells, v conc Is the concentration voltage loss caused by the concentration drop of the reactant during the reaction.
6. The method for estimating anode nitrogen concentration of fuel cell based on multipoint voltage according to claim 5, wherein: in the step D, it is assumed that the partial pressure of nitrogen in the anode outlet cavity of the first cell isThe partial pressure of nitrogen in the anode outlet chamber 2 of the j-th cell is +.>Then there are:
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