CN112768735B - Estimation method of tail exhaust hydrogen concentration of fuel cell system - Google Patents
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- 239000001257 hydrogen Substances 0.000 title claims abstract description 158
- 229910052739 hydrogen Inorganic materials 0.000 title claims abstract description 158
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 title claims abstract description 157
- 238000000034 method Methods 0.000 title claims abstract description 41
- 239000000446 fuel Substances 0.000 title claims abstract description 30
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 21
- 230000036284 oxygen consumption Effects 0.000 claims abstract description 15
- 239000007789 gas Substances 0.000 claims description 25
- -1 hydrogen Chemical class 0.000 claims description 8
- 238000002347 injection Methods 0.000 claims description 5
- 239000007924 injection Substances 0.000 claims description 5
- 238000013461 design Methods 0.000 claims description 4
- 238000012935 Averaging Methods 0.000 claims description 3
- YZCKVEUIGOORGS-NJFSPNSNSA-N Tritium Chemical compound [3H] YZCKVEUIGOORGS-NJFSPNSNSA-N 0.000 claims 1
- 150000002431 hydrogen Chemical class 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 238000005259 measurement Methods 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 238000007789 sealing Methods 0.000 description 4
- 230000000670 limiting effect Effects 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 239000012528 membrane Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- YZCKVEUIGOORGS-IGMARMGPSA-N Protium Chemical compound [1H] YZCKVEUIGOORGS-IGMARMGPSA-N 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000003487 electrochemical reaction Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 239000002360 explosive Substances 0.000 description 1
- 230000014509 gene expression Effects 0.000 description 1
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 1
- GPRLSGONYQIRFK-UHFFFAOYSA-N hydron Chemical compound [H+] GPRLSGONYQIRFK-UHFFFAOYSA-N 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 230000002829 reductive effect Effects 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
- H01M8/04298—Processes for controlling fuel cells or fuel cell systems
- H01M8/04313—Processes for controlling fuel cells or fuel cell systems characterised by the detection or assessment of variables; characterised by the detection or assessment of failure or abnormal function
- H01M8/0444—Concentration; Density
- H01M8/04462—Concentration; Density of anode exhausts
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
- H01M8/04298—Processes for controlling fuel cells or fuel cell systems
- H01M8/04992—Processes for controlling fuel cells or fuel cell systems characterised by the implementation of mathematical or computational algorithms, e.g. feedback control loops, fuzzy logic, neural networks or artificial intelligence
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- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
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Abstract
The invention provides a method for estimating the concentration of tail exhaust hydrogen of a fuel cell system, which comprises the following steps: s1: obtaining the instantaneous molar flow of hydrogen entering the galvanic pile
S2: collecting the air flow entering the galvanic pile to obtain the instantaneous molar flow of the air
S3: calculating the molar flow consumed by hydrogen consumed in real time according to the current, the air excess coefficient ratio and the voltage
And oxygen consumption molar flow
S4: measuring the ambient temperature and the ambient pressure at the tail row, calculating to obtain the mole fraction of the water vapor at the tail row,
wherein p issatIs the saturation pressure of water vapour, patmIs at ambient pressure; s5: the tail out hydrogen concentration was calculated according to the following formula,
Description
Technical Field
The invention belongs to the field of fuel cells, and particularly relates to a method for estimating the concentration of tail exhaust hydrogen of a fuel cell system.
Background
The proton exchange membrane fuel cell works on the principle that hydrogen and oxygen generate electrochemical reaction to generate water and output electric energy. Wherein, hydrogen is used as combustible gas, and when the volume concentration of the hydrogen in the air is in the range of 4.0-75.6%, explosion can occur when encountering a fire source. Therefore, it is necessary for safety of the system and personnel to always control the hydrogen concentration at the exhaust gas discharge outlet of the fuel cell system (tail gas discharge hydrogen concentration) to be below the explosive concentration.
With the long-term operation of the fuel cell system, the efficiency of the fuel cell stack is reduced, and the tail discharge hydrogen concentration is increased due to potential hydrogen leakage, the reduction of the sealing performance of a tail discharge valve or a polar plate, the reduction of the sealing performance of a hydrogen nozzle and the like. Therefore, it is necessary to develop a method for estimating (measuring) the tail hydrogen concentration on line, so as to take effective measures to ensure safety in time when the excessive tail hydrogen concentration is detected.
Currently, the tail exhaust hydrogen concentration is usually detected by installing a hydrogen concentration sensor in the tail exhaust pipeline or using a handheld hydrogen concentration detector at the tail exhaust port. However, liquid water that may be present in the vented gases can cause the hydrogen concentration sensor to fail, and installing the hydrogen concentration sensor can increase the cost and complexity of the system. The mode of utilizing the handheld detection instrument is only suitable for being carried out in the development process of a laboratory environment, and the detection requirement of real-time running under the vehicle environment cannot be met.
For example, the limited liability company of general automobile global technology operation discloses a liquid water protection measure for a gas hydrogen sensor in a fuel cell exhaust system in chinese patent CN103107346B, which avoids the failure of the hydrogen concentration sensor caused by tail-exhausted liquid water by improving the structural design of the hydrogen concentration sensor. This solution still requires additional installation of a hydrogen concentration sensor and an improved structure, increasing the cost and complexity of the system.
For another example, chinese patent CN101292384B by toyota automotive co discloses a fuel cell system, an anode gas generation amount estimation device, and an anode gas generation amount estimation method, in which the concentration of tail exhaust hydrogen gas is estimated when the fuel cell system is operating at low efficiency, and a method of reducing the concentration of tail exhaust hydrogen is specifically adopted. However, this estimation method is to derive the pumping hydrogen amount and the discharging hydrogen amount only for the MAP based on experimental measurement, and does not consider other cases such as deterioration of sealing performance, and non-inefficient operation cases.
Disclosure of Invention
Therefore, the present invention is directed to provide a method for estimating a tail-gas hydrogen concentration of a fuel cell system, which is suitable for a wide range of applications and does not require additional components.
The purpose of the invention is realized by the following technical scheme.
The invention provides a method for estimating the concentration of tail exhaust hydrogen of a fuel cell system, wherein the method comprises the following steps:
s1: obtaining the instantaneous molar flow of hydrogen entering the galvanic pile
S2: collecting the air flow entering the galvanic pile to obtain the instantaneous molar flow of the air
S3: calculating the molar flow consumed by hydrogen consumed in real time according to the current, the air excess coefficient ratio and the voltage
And oxygen consumption molar flow
S4: measuring the ambient temperature and the ambient pressure at the tail discharge position, and calculating to obtain the water vapor mole fraction x at the tail discharge positionh2o；
Wherein p issatIs saturation of water vaporPressure, patmIs at ambient pressure;
s5: calculating the tail bleed concentration x according toh2；
Preferably, step S1 includes the steps of:
s101: collecting input end pressure and output end pressure of a hydrogen flow control device of a fuel cell system and a control signal of a controller of the hydrogen flow control device;
s102: inquiring a hydrogen flow MAP of a pre-calibrated hydrogen instantaneous mass flow-ratio of the pressure of the input end to the pressure of the output end-control signal according to the acquired pressure of the input end, the pressure of the output end and the control signal to obtain the hydrogen instantaneous mass flow
And
s103: based on the instantaneous mass flow of hydrogen
Calculating to obtain the instantaneous molar flow of hydrogen
More preferably, the control signal may be determined according to the type of the hydrogen flow control device. For example, the hydrogen flow control device is a hydrogen gas injector, and the control signal is an injection pulse width θ of the nozzle. Accordingly, the input end pressure is the inlet pressure of the hydrogen injector; the output pressure is the outlet pressure of the hydrogen injector; the instantaneous mass flow of the hydrogen is the real-time injection mass flow of the hydrogen injector.
More preferably, step S102 further comprises the steps of: collecting temperature signal T of input end of hydrogen flow control device0Combined with the temperature signal T at the input when calibrating the hydrogen flow MAP0,mapObtaining the hydrogen flow MAP by querying the hydrogen flow MAPInstantaneous flow rate of hydrogen
Correcting to obtain the instantaneous mass flow of the hydrogen
Wherein,
further preferably, T0＝T0,mapThen, then
More preferably, the instantaneous molar flow rate of hydrogen is calculated in step S103 by the following formula
Wherein M ish2Is the molar mass of the hydrogen gas,
the pressure drop rate of an anode cavity of the galvanic pile is shown, V is the volume of the anode cavity of the galvanic pile, R is a general gas constant, and T is the temperature of the galvanic pile.
Preferably, the tail gate valve of the fuel cell system is in a closed state, and the anode chamber pressure drop rate
Is zero. At this time, the process of the present invention,
preferably, the instantaneous mass flow of hydrogen is measured by a hydrogen flow meter in step S1
Likewise, the instantaneous molar flow of hydrogen can be calculated by the following formula
Wherein M ish2Is the molar mass of the hydrogen gas,
the pressure drop rate of an anode cavity of the galvanic pile is shown, V is the volume of the anode cavity of the galvanic pile, R is a general gas constant, and T is the temperature of the galvanic pile;
more preferably, the rate of pressure drop in the anode volume
May be zero.
Preferably, in step S3, when the air excess coefficient ratio is greater than 1.4, the molar flow rate of consumption of hydrogen gas consumed in real time is calculated according to the following formula
And oxygen consumption molar flow
Wherein i is the current of the electric pile, and N is the number of single pieces of the electric pile;
when the air excess coefficient ratio is less than or equal to 1.4, adoptingCollecting stack current, air excess coefficient ratio and stack voltage, inquiring a hydrogen consumption MAP (MAP of hydrogen consumption-stack current-air excess coefficient ratio-stack current) calibrated in advance to obtain real-time consumed hydrogen consumption molar flow
And oxygen consumption molar flow
Preferably, the estimation method further comprises the steps of:
s6: tail bleed hydrogen concentration x according toh2Modifying to obtain the corrected tail exhaust hydrogen concentration xfinal；
xfinal＝C·xh2
Wherein C is a pipeline design factor.
More preferably, the coefficient C may be obtained by averaging the ratios of the measured values to the estimated values of the tail gas hydrogen concentration.
Preferably, xh2o＝0。
The estimation method of the invention has the following advantages:
1. the following disadvantages existing in the prior art can be avoided: the hydrogen concentration sensor and the improved measurement of the tail exhaust hydrogen concentration need additional parts, avoid the problems of sensor failure caused by liquid water and the like, and increase the cost and the system complexity.
2. The estimation method of the invention can be used for estimating the tail exhaust hydrogen concentration under the conditions of leakage and the like. Without wishing to be bound by theory, it is believed that hydrogen gas is still generally discharged from the tail gas when leakage occurs due to decreased sealing performance, hydrogen empty string leakage, etc., and the estimation method of the present invention can be applied to this case, and is more applicable.
In addition, the estimation method of the invention has the following advantages: the periodic pressure difference change is not required to be formed on two sides of a reaction membrane of the fuel cell during measurement, so that the service life of the fuel cell is not adversely affected; the dependence on the resolution of the pressure sensor and the temperature sensor is low, and the measurement accuracy is high.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
fig. 1 shows a schematic structural diagram of a fuel cell system;
FIG. 2 shows the absolute error between the estimated and measured tail out hydrogen concentration values for a plurality of test sequences;
wherein the figures include the following reference numerals:
the system comprises a high-pressure hydrogen source 1, a hydrogen flow control device 2, a galvanic pile 3, a tail row electromagnetic valve 4, a mixing cavity 5, a throttle valve 6, an air compressor 7, an air flow meter 8, a controller 9 and a tail row pipeline 10.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
The relative arrangement of the components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise. Meanwhile, it should be understood that the sizes of the respective portions shown in the drawings are not drawn in an actual proportional relationship for the convenience of description. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate. In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.
The invention provides a method for estimating the concentration of tail exhaust hydrogen of a fuel cell system, wherein the method comprises the following steps:
s1: obtaining the instantaneous molar flow of hydrogen entering the galvanic pile
S2: collecting the air flow entering the galvanic pile to obtain the instantaneous molar flow of the air
S3: calculating the molar flow consumed by hydrogen consumed in real time according to the current, the air excess coefficient ratio and the voltage
And oxygen consumption molar flow
S4: measuring the ambient temperature and the ambient pressure at the tail discharge position, and calculating to obtain the water vapor mole fraction x at the tail discharge positionh2o；
Wherein p issatIs the saturation pressure of water vapour, patmIs at ambient pressure;
s5: calculating the tail bleed concentration x according toh2；
Fig. 1 shows an embodiment of a fuel cell system. Referring to fig. 1, the fuel cell system includes a hydrogen flow rate control device 2, a cell stack 3, a tail exhaust solenoid valve 4, a mixing chamber 5, a throttle valve 6, an air compressor 7, an air flow meter 8, a controller 9, and a tail exhaust line 10.
Under the regulation control of the controller 9, the high-pressure hydrogen source 1 is fed into the electric pile 3 through the hydrogen flow control device 2. And air is pressurized by an air compressor 7 and fed into the cell stack 3, and the flow rate of air entering the cell stack 3 is measured by an air flow meter 8 provided upstream of the air compressor 7. The reacted hydrogen and air enter the mixing cavity 5 to be mixed under the control of the tail exhaust electromagnetic valve 4 and the throttle valve 6 respectively, and then are exhausted into the atmosphere through the tail exhaust pipeline 10.
The method for estimating the concentration of the tail exhaust hydrogen of the fuel cell system comprises the following steps:
s1: obtaining the instantaneous molar flow of hydrogen entering the galvanic pile 3
S2: collecting the air flow entering the galvanic pile 3 to obtain the instantaneous molar flow of the air
S3: calculating the molar flow consumed by hydrogen consumed in real time according to the current, the air excess coefficient ratio and the voltage
And oxygen consumption molar flow
S4: measuring the ambient temperature and the ambient pressure at the tail discharge position, and calculating to obtain the water vapor mole fraction x at the tail discharge positionh2o；
Wherein p issatIs the saturation pressure of water vapour, patmIs at ambient pressure;
s5: calculating the tail bleed concentration x according toh2；
In the present invention, the tail pipe is generally referred to as the tail pipe 10.
According to an embodiment of the present invention, step S1 includes the following steps:
s101: collecting the input end pressure and the output end pressure of a hydrogen flow control device 2 of the fuel cell system and a control signal of a controller 9 of the hydrogen flow control device 2;
s102: inquiring a hydrogen flow MAP of a pre-calibrated hydrogen instantaneous mass flow-ratio of the pressure of the input end to the pressure of the output end-control signal according to the acquired pressure of the input end, the pressure of the output end and the control signal to obtain the hydrogen instantaneous mass flow
And
s103: based on the instantaneous mass flow of hydrogen
Calculating to obtain the instantaneous molar flow of hydrogen
According to an embodiment of the present invention, the control signal may be determined according to the type of the hydrogen flow control device 2. For example, if the hydrogen flow control device 2 is a hydrogen injector, the control signal is typically the injection pulse width θ of the nozzle. Accordingly, the input end pressure is the inlet pressure of the hydrogen injector; the output pressure is the outlet pressure of the hydrogen injector; the instantaneous mass flow of the hydrogen is the real-time injection mass flow of the hydrogen injector.
According to one embodiment of the present invention, the ratio of the input pressure to the output pressure is expressed as
Wherein p is1For input end pressure, p0Is the input end pressure.
According to an embodiment of the present invention, step S102 further includes the following steps: collecting the temperature signal T of the input end of the hydrogen flow control device 20Temperature signal T at input in conjunction with calibrated hydrogen flow MAP0,mapFor the instantaneous flow of hydrogen obtained by looking up the MAP
Correcting to obtain the instantaneous mass flow of the hydrogen
Wherein,
according to an embodiment of the present invention, T0＝T0,map，
According to an embodiment of the present invention, when the tail valve of the fuel cell system is opened, the pressure in the anode chamber will decrease rapidly, and the hydrogen flow rate needs to consider the loss flow rate in the chamber, and for the sake of simplicity, it is assumed that the chamber is hydrogen at this time,then the flow is lost
Comprises the following steps:
wherein,
the pressure drop rate of the anode cavity of the galvanic pile is shown; v is the volume of the anode containing cavity of the galvanic pile; r is a universal gas constant; t is the temperature of the stack.
According to an embodiment of the present invention, the loss flow rate can also be calculated by the above equation during the opening of the tail gate valve of the fuel cell system.
Therefore, the instantaneous molar flow rate of hydrogen can be calculated by the following formula in step S103
Wherein M ish2Is the molar mass of hydrogen, typically 2.016 g/mol;
the pressure drop rate of the anode cavity of the galvanic pile is shown; v is the volume of the anode containing cavity of the galvanic pile; r is a universal gas constant; t is the temperature of the stack.
According to one embodiment of the invention, the tail gate valve 4 of the fuel cell system is in a closed state and the anode volume pressure drops at a rate
Is zero, and at this time,
according to an embodiment of the present invention, in step S1, the instantaneous mass flow rate of hydrogen is measured by a hydrogen flowmeter
In this case, the instantaneous molar flow rate of hydrogen can be calculated by the following formula
Wherein M ish2Is the molar mass of the hydrogen gas,
the pressure drop rate of an anode cavity of the galvanic pile is shown, V is the volume of the anode cavity of the galvanic pile, R is a general gas constant, and T is the temperature of the galvanic pile.
Similarly, the rate of pressure drop in the anode volume
Or may be zero. At this time, the process of the present invention,
according to an embodiment of the present invention, in step S2, the air flow meter 8 is used to collect the instantaneous mass flow of air entering the system
And converted into instantaneous molar flow of air by the following formula
Wherein M isairThe molar mass of air is usually 28.966 g/mol.
According to an embodiment of the invention, the instantaneous molar flow rate of air in step S2 takes into account that part of the air flow may not enter the mixing chamber 5 but be discharged directly to the atmosphere
Means an effective molar flow rate, which should be removed for discharge into the atmosphere.
According to an embodiment of the present invention, in step S3, when the air excess coefficient ratio is greater than 1.4, the real-time consumed hydrogen consumption molar flow rate is calculated according to the following formula
And oxygen consumption molar flow
Wherein i is the current of the electric pile, and N is the number of the single electric pile.
When the air excess coefficient ratio is less than or equal to 1.4, the galvanic pile operates in low efficiency, and part of hydrogen is transported to the cathode in a hydrogen ion mode and synthesized into hydrogen again with electrons, and the hydrogen consumption is lower than that calculated based on current. In this case, the current of the pile, the air excess coefficient ratio and the voltage of the pile are collected, a hydrogen consumption MAP graph of pre-calibrated hydrogen consumption-pile current-air excess coefficient ratio-pile current is inquired, and the real-time consumption molar flow of hydrogen consumption is obtained
And oxygen consumption molar flow
Wherein hydrogen gas is consumed in molar flow
Can be obtained by inquiring a MAP of hydrogen consumption MAP and oxygen consumption molar flow
Calculated by the reaction 2H2+ O2 → 2H 2O.
According to an embodiment of the present invention, considering that the exhaust gas with high temperature and high humidity undergoes the process of temperature reduction and condensation of water vapor when passing through the tail discharge port, the relative humidity of the mixed gas at the tail discharge port is generally 100%. Thus, in the estimation method of the present invention, the mole fraction x of water vapor at the tail gas is calculated from the ambient temperature and pressureh2o。
According to an embodiment of the present invention, the tail stack hydrogen concentration may also be affected by the tail stack mixing chamber and the tail stack piping. The estimation method of the present invention further comprises the steps of:
s6: tail bleed hydrogen concentration x according toh2Modifying to obtain the corrected tail exhaust hydrogen concentration xfinal；
xfinal＝C·xh2
Wherein C is a pipeline design factor.
According to an embodiment of the present invention, the coefficient C may be obtained by averaging the ratio of the measured value to the estimated value of the tail gas hydrogen concentration. In one embodiment, the coefficient C is 1.
According to an embodiment of the present invention, since the ratio of water vapor in the tail exhaust mixture is small, the influence of water vapor, x, can be ignoredh2o＝0。
Example 1
The estimation method is implemented by adopting the experimental equipment and instruments described in GB/T37154-.
The estimation method comprises the following steps:
s1: the instantaneous molar flow of hydrogen entering the galvanic pile 3 is obtained by the following steps
S101: the input and output end pressures of the hydrogen flow rate control device 2 of the fuel cell system and the control signal of the controller 9 of the hydrogen flow rate control device 2 are collected.
S102: inquiring a hydrogen flow MAP of a pre-calibrated hydrogen instantaneous mass flow-ratio of the pressure of the input end to the pressure of the output end-control signal according to the acquired pressure of the input end, the pressure of the output end and the control signal to obtain the hydrogen instantaneous mass flow
Wherein the ratio of the input pressure to the output pressure is recorded as
Wherein p is1For input end pressure, p0Is the input end pressure.
For simplicity of operation, the temperature signal T at the input of the hydrogen flow control device 2 is controlled0Constant and equal to the temperature T at the input of the MAP of the nominal hydrogen flow0,mapAt this time
S103: based on the instantaneous mass flow of hydrogen
Calculating to obtain the instantaneous molar flow of hydrogen
Wherein M ish2Is the molar mass of hydrogen, typically 2.016 g/mol;
the pressure drop rate of the anode cavity of the galvanic pile is shown; v is the volume of the anode containing cavity of the galvanic pile; r is a universal gas constant; t is the temperature of the stack.
S2: the air flow meter 8 is used for collecting the instantaneous mass flow of the air entering the electric pile 3
Obtaining the instantaneous molar flow of air
Wherein,
wherein M isairThe molar mass of air is usually 28.966 g/mol.
S3: calculating the molar flow consumed by hydrogen consumed in real time according to the current, the air excess coefficient ratio and the voltage
And oxygen consumption molar flow
When the air excess factor ratio is greater than 1.4, the molar flow rate of consumption of hydrogen consumed in real time is calculated according to the following formula
And oxygen consumption molar flow
Wherein i is the current of the electric pile, and N is the number of the single electric pile.
When the air excess coefficient ratio is less than or equal to 1.4, collecting the current of the galvanic pile, the air excess coefficient ratio and the voltage of the galvanic pile, inquiring a hydrogen consumption MAP (MAP) chart of pre-calibrated hydrogen consumption-galvanic pile current-air excess coefficient ratio-galvanic pile current to obtain the real-time consumed hydrogen consumption molar flow
And oxygen consumption molar flow
Wherein the molar flow of oxygen is consumed
Molar flow rate consumption for hydrogen
1/2 of (1).
S4: measuring the ambient temperature and the ambient pressure at the tail discharge position, and calculating to obtain the water vapor mole fraction x at the tail discharge positionh2o；
Wherein p issatIs the saturation pressure of water vapour, patmIs at ambient pressure.
S5: the parameter C is recorded as 1, and the tail hydrogen discharge concentration x is calculated according to the following formulah2；
Fig. 2 shows the absolute error of the tail bleed hydrogen concentration for different power point test sequences. As shown in FIG. 2, under different power point test sequences, the estimation absolute error is less than 0.5%, and the estimation method of the invention is accurate and reliable.
In the description of the present invention, it is to be understood that the orientation or positional relationship indicated by the orientation words such as "front, rear, upper, lower, left, right", "lateral, vertical, horizontal" and "top, bottom", etc. are usually based on the orientation or positional relationship shown in the drawings, and are only for convenience of description and simplicity of description, and in the case of not making a reverse description, these orientation words do not indicate and imply that the device or element being referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore, should not be considered as limiting the scope of the present invention; the terms "inner and outer" refer to the inner and outer relative to the profile of the respective component itself.
Spatially relative terms, such as "above … …," "above … …," "above … …," "above," and the like, may be used herein for ease of description to describe one device or feature's spatial relationship to another device or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is turned over, devices described as "above" or "on" other devices or configurations would then be oriented "below" or "under" the other devices or configurations. Thus, the exemplary term "above … …" can include both an orientation of "above … …" and "below … …". The device may be otherwise variously oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
It should be noted that the terms "first", "second", and the like are used to define the components, and are only used for convenience of distinguishing the corresponding components, and the terms have no special meanings unless otherwise stated, and therefore, the scope of the present invention should not be construed as being limited.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (9)
1. A method of estimating a tail gas hydrogen concentration of a fuel cell system, wherein the estimating method comprises the steps of:
s1: obtaining the instantaneous molar flow of hydrogen entering the galvanic pile
S2: collecting the air flow entering the galvanic pile to obtain the instantaneous molar flow of the air
S3: calculating the molar flow consumed by hydrogen consumed in real time according to the current, the air excess coefficient ratio and the voltage
And oxygen consumption molar flow
S4: measuring the ambient temperature and the ambient pressure at the tail discharge position, and calculating to obtain the water vapor mole fraction x at the tail discharge positionh2o；
Wherein p issatIs the saturation pressure of water vapour, patmIs at ambient pressure;
s5: calculating the tail bleed concentration x according toh2；
2. The estimation method according to claim 1, wherein step S1 includes the steps of:
s101: collecting input end pressure and output end pressure of a hydrogen flow control device of a fuel cell system and a control signal of a controller of the hydrogen flow control device;
s102: inquiring a hydrogen flow MAP of a pre-calibrated hydrogen instantaneous mass flow-ratio of the pressure of the input end to the pressure of the output end-control signal according to the acquired pressure of the input end, the pressure of the output end and the control signal to obtain the hydrogen instantaneous mass flow
And
s103: based on the instantaneous mass flow of hydrogen
Calculating to obtain the instantaneous molar flow of hydrogen
3. The estimation method according to claim 2, wherein the hydrogen flow rate control device is a hydrogen gas injector, and the control signal is an injection pulse width θ of a nozzle.
4. The estimation method according to claim 2 or 3, wherein step S102 further comprises the steps of: collecting temperature signal T of input end of hydrogen flow control device0An input end for calibrating the hydrogen flow MAPTemperature signal T of0,mapFor the instantaneous hydrogen flow obtained by inquiring the MAP
Correcting to obtain the instantaneous mass flow of the hydrogen
Wherein,
5. the estimation method according to claim 4, wherein the instantaneous molar flow rate of hydrogen is calculated by the following formula in step S103
Wherein M ish2Is the molar mass of the hydrogen gas,
the pressure drop rate of an anode cavity of the galvanic pile is shown, V is the volume of the anode cavity of the galvanic pile, R is a general gas constant, and T is the temperature of the galvanic pile.
6. The estimation method according to claim 1, wherein the instantaneous mass flow of hydrogen is measured by a hydrogen flow meter in step S1
Wherein hydrogen is calculated by the following formulaInstantaneous molar flow of gas
Wherein M ish2Is the molar mass of the hydrogen gas,
the pressure drop rate of an anode cavity of the galvanic pile is shown, V is the volume of the anode cavity of the galvanic pile, R is a general gas constant, and T is the temperature of the galvanic pile.
7. The estimation method according to claim 6, wherein, in step S3, when the air excess coefficient ratio is larger than 1.4, the molar flow rate of consumption of hydrogen gas to be consumed in real time is calculated according to the following formula
And oxygen consumption molar flow
Wherein i is the current of the electric pile, and N is the number of single pieces of the electric pile;
when the air excess coefficient ratio is less than or equal to 1.4, collecting the pile current, the air excess coefficient ratio and the pile voltage, inquiring a hydrogen consumption MAP (MAP of hydrogen consumption-pile current-air excess coefficient ratio-pile current) calibrated in advance, and obtaining real-time dataMolar flow of hydrogen consumed
And oxygen consumption molar flow
8. The estimation method according to claim 7, wherein the estimation method further comprises the steps of:
s6: tail bleed hydrogen concentration x according toh2Modifying to obtain the corrected tail exhaust hydrogen concentration xfinal；
xfinal＝C·xh2
Wherein C is a pipeline design coefficient obtained by averaging the ratio of the measured value to the estimated value of the tail gas hydrogen concentration.
9. The estimation method according to claim 8, wherein xh2o＝0。
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| CN114497649B (en) * | 2022-01-11 | 2024-04-09 | 一汽解放汽车有限公司 | Fault recognition device and fault recognition method for hydrogen pressure sensor of in-stack |
| CN119050416B (en) * | 2024-10-30 | 2025-02-18 | 国网浙江省电力有限公司电力科学研究院 | System and method for measuring and calculating hydrogen concentration on line of fuel cell system circulation path |
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