CN115425255A - Ejector and gas supply circulating system for fuel cell - Google Patents

Ejector and gas supply circulating system for fuel cell Download PDF

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CN115425255A
CN115425255A CN202211026078.1A CN202211026078A CN115425255A CN 115425255 A CN115425255 A CN 115425255A CN 202211026078 A CN202211026078 A CN 202211026078A CN 115425255 A CN115425255 A CN 115425255A
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ejector
working
fuel cell
gas
eductor
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陈红
朱文若
齐济
王绍成
安灿灿
胡朝阳
徐凯
吴绍伟
孙凤焕
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Beijing Aerospace Propulsion Institute
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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
    • H01M8/04082—Arrangements for control of reactant parameters, e.g. pressure or concentration
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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
    • H01M8/04082—Arrangements for control of reactant parameters, e.g. pressure or concentration
    • H01M8/04089—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants
    • H01M8/04097—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants with recycling of the reactants
    • 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
    • H01M8/04694—Processes for controlling fuel cells or fuel cell systems characterised by variables to be controlled
    • H01M8/04746—Pressure; Flow
    • H01M8/04753—Pressure; Flow of fuel cell reactants
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • 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 application relates to the ejector field, specifically discloses an ejector, and the gas supply circulation system that the ejector used includes: the device comprises a fuel cell, a target gas source, a pressure regulating valve, an ejector and a switch valve; the pressure regulating valve and the ejector are connected in parallel between the fuel cell and a target gas source; the working inlet of the ejector is connected with a target gas source, target gas exhausted by the fuel cell enters the ejector through the ejector inlet and is mixed with the target gas input by the working inlet, and the mixed target gas is output to the fuel cell through the ejector outlet; the ejector is applied to N working conditions, the N working conditions correspond to N reachable ejection coefficients one by one, and under each working condition in the N working conditions, the design ejection coefficient of the ejector is smaller than the reachable ejection coefficient corresponding to each working condition. The ejector provided by the application can provide constant working flow for the fuel cell in all working conditions, and meet the hydrogen circulation quantity of the fuel cell demand.

Description

Ejector and gas supply circulating system for fuel cell
Technical Field
The application relates to the technical field of ejectors, in particular to an ejector and a gas supply circulation system for a fuel cell.
Background
The fuel cell hydrogen path requires an excess supply of hydrogen gas. In order to improve the utilization rate of hydrogen, a common scheme is that a hydrogen recirculation system is established to send the unreacted hydrogen at the outlet of the galvanic pile to an inlet after gas-water separation and mix with a main gas path for reutilization, and the effects of hydrogen circulation and inlet hydrogen humidification are achieved. The ejector has no moving parts, has better mechanical stability and has incomparable advantages in volume and weight with a mechanical pump, so the ejector is often applied to a hydrogen supply and circulation system.
In the actual use process, the structural design of the ejector is unreasonable, so that the working range of the gas supply circulation system where the ejector is located is too narrow, and the ejector cannot adapt to the full operating condition of the galvanic pile. Specifically, the problem of insufficient ejector capacity may occur in any of the cases where the stack consumption is at the maximum, minimum, large, small, and the like. The ejector with unreasonable structural design has weak adaptability to the variable load of the stack, so that the working stability of the single ejector system is difficult to guarantee when the fuel cell is started or stopped and the load is changed. How to be through optimizing the ejector structure to the injection volume that guarantees the ejector to provide is no less than the excessive hydrogen circulation volume of galvanic pile, is the technical problem that needs to solve.
Disclosure of Invention
The application provides an ejector and a gas supply circulation system who is used for fuel cell, and the purpose provides a reasonable in design structure's ejector, when this ejector is applied to the gas supply circulation system that this application provided, can be when operating pressure is constant, for fuel cell provides invariable work flow in the operating condition to and satisfy the hydrogen circulation volume of fuel cell demand.
In a first aspect, there is provided an injector for use in a gas supply circulation system, the gas supply circulation system comprising:
a fuel cell;
a target gas source for supplying a target gas to the fuel cell;
the pressure regulating valve and the ejector are connected in parallel between the fuel cell and the target gas source;
the ejector comprises a working inlet, an ejector inlet and an ejector outlet, the working inlet is connected with the target gas source, the target gas exhausted by the fuel cell enters the ejector through the ejector inlet and is mixed with the target gas input by the working inlet, and the mixed target gas is output to the fuel cell through the ejector outlet;
the ejector is applied to N operating modes, and the ejector meets the following requirements:
under a target working condition in the N working conditions, the design injection coefficient of the injector is smaller than the reachable injection coefficient corresponding to the target working condition,
and under other working conditions in the N working conditions, the actual injection coefficient of the working condition of the ejector is not less than the designed injection system corresponding to the working condition of the ejector.
Compared with the prior art, the scheme provided by the application at least comprises the following beneficial technical effects:
the ejector that this application designed is adaptable in parallelly connected novel hydrogen supply and circulation system of a pressure regulating valve and ejector, can guarantee to provide invariable work flow in full operating mode to and be no less than the hydrogen circulation volume of fuel cell demand. The control difficulty of the regulating valve is reduced while sufficient hydrogen is supplied to the galvanic pile in the full working condition range, the outlet pressure vibration caused by the synchronous flow fluctuation coupling of the pressure regulating valve and the ejector is avoided,
with reference to the first aspect, in certain implementation manners of the first aspect, the N working conditions correspond to the N reachable injection coefficients one by one, and the reachable injection coefficient corresponding to the target working condition is a minimum value of the N reachable injection coefficients.
The minimum value of the N reachable injection coefficients is larger than the designed injection coefficient under the full working condition, the injection flow of the injector is larger than the hydrogen circulation required by the current working condition, and the workload of injection capability verification under the N working conditions is favorably reduced.
With reference to the first aspect, in certain implementations of the first aspect, the design ejection coefficient U = G h /G P The injection flow G of the ejector h = Q × (i-1), the ejector working flow rate G P ＝G Minimum consumption -G Pressure regulating valve Q is the maximum electric pile consumption or the electric pile consumption under the working condition corresponding to the designed injection coefficient, i is the excess coefficient, G Minimum consumption Minimum stack consumption when opening the eductor for gas supply cycle system, G Pressure regulating valve And the minimum flow regulating value of the pressure regulating valve is used.
When the injection coefficient is calculated and designed by utilizing the maximum electric pile consumption, the injector meeting the use requirement of all working conditions can be obtained through single design.
With reference to the first aspect, in certain implementations of the first aspect, the achievable injection coefficient u satisfies:
Figure BDA0003815667310000031
Figure BDA0003815667310000032
Figure BDA0003815667310000033
coefficient of velocity of nozzle
Figure BDA0003815667310000034
Velocity coefficient of mixing chamber
Figure BDA0003815667310000035
Velocity coefficient of diffuser
Figure BDA0003815667310000036
Coefficient of velocity of the inlet section of the mixing chamber
Figure BDA0003815667310000037
Δp c ＝p c -p H ；P c -P h ＝ξ Electric pile *(Q Consumption of +G h ) 2 /ρ Saturated wet hydrogen +ξ Gas-water separation *G h 2 /ρ Saturated wet hydrogen ；
υ p Specific volume of working gas; upsilon is H Injecting specific gas volume; upsilon is c Is the specific volume of the mixed gas;
p p is the working gas pressure; p is a radical of H For injecting gas pressure; p is a radical of c Is the mixed gas pressure;
k p is the working gas adiabatic index; k is a radical of H Is the injection gas adiabatic index; k is a radical of c Is the adiabatic index of the mixed gas;
λ pH is a reduced isentropic velocity; n =1.01 to 1.08.
With reference to the first aspect, in certain implementations of the first aspect, the operating gas pressure P of the ejector is at a maximum stack consumption p And injection gas pressure P h Satisfies the following conditions:
expansion ratio P of working gas in the ejector P /P h Greater than the critical pressure ratio.
Therefore, the ejector is beneficial to working stability.
With reference to the first aspect, in certain implementations of the first aspect, a nozzle throat diameter of the eductor
Figure BDA0003815667310000041
Figure BDA0003815667310000042
Is the critical area of the nozzle throat;
Figure BDA0003815667310000043
with reference to the first aspect, in certain implementations of the first aspect, the injector has a nozzle opening diameter
Figure BDA0003815667310000044
Figure BDA0003815667310000049
q p1 And the expansion ratio P in the N working conditions P /P h The minimum value in (1) corresponds to.
With reference to the first aspect, in certain implementations of the first aspect, the diameter of the ejector mixing chamber
Figure BDA0003815667310000045
|f p3 -f 3 The | < a preset threshold value;
Figure BDA0003815667310000046
Figure BDA0003815667310000047
Figure BDA0003815667310000048
with reference to the first aspect, in certain implementations of the first aspect, d 4 ＝1.55d p1 (1+u) distance l of the ejector nozzle from the mixing chamber c Satisfies the following conditions:
when d is 3 ＞d 4 When l is turned on c ＝l c1 ，
Figure BDA0003815667310000051
l c1 Is the length of the free stream at the nozzle outlet, j is the experimental constant;
when d is 3 ＜d 4 When l is turned on c ＝l c1 +l c2 ，
Figure BDA0003815667310000052
l c2 For the length of the mixing chamber inlet section, β is the cone angle of the mixing chamber inlet section.
With reference to the first aspect, in certain implementations of the first aspect, the length l of the ejector mixing chamber K Is 6 to 10 times of the diameter d of the mixing chamber 3 。
In a second aspect, there is provided a gas supply circulation system comprising:
a fuel cell;
a target gas source for supplying a target gas to the fuel cell;
a pressure regulating valve and the ejector as described in any one of the implementations of the first aspect above, the pressure regulating valve and the ejector being connected in parallel between the fuel cell and the target gas source;
the ejector comprises a working inlet, an ejector inlet and an ejector outlet, the working inlet is connected with the target gas source, target gas exhausted by the fuel cell enters the ejector through the ejector inlet and is mixed with the target gas input by the working inlet, and the mixed target gas is output to the fuel cell through the ejector outlet.
Drawings
Fig. 1 is a schematic structural diagram of a gas supply circulation system according to an embodiment of the present application.
Fig. 2 is a schematic structural diagram of an ejector according to an embodiment of the present application.
Fig. 3 is a schematic structural diagram of an ejector according to an embodiment of the present application.
Detailed Description
The present application is described in further detail below with reference to the figures and the specific embodiments.
The embodiment of the application discloses gas supply circulation system, refer to fig. 1, including hydrogen source, one-level relief pressure valve, pressure regulating valve, ooff valve, ejector, fuel cell.
The hydrogen source may supply hydrogen to the fuel cell to provide the fuel cell stack with a desired consumption of hydrogen. The pressure regulating valve and the ejector are connected in parallel between the fuel cell and the hydrogen source. After flowing out from the hydrogen source, the hydrogen is decompressed by the primary pressure reducing valve and respectively enters the pressure regulating valve branch, the electromagnetic valve and the ejector branch. As shown in FIG. 1, the outlet side of the primary pressure reducing valve may be provided with a pressure sensor P 0 . The primary pressure reducing valve can be used for reducing the pressure of a hydrogen source, and the pressure values of the pressure regulating valve and the front end of the ejector are guaranteed to be constant.
Fig. 2 is a schematic structural diagram of an ejector provided in an embodiment of the present application. With reference to fig. 1 and 2, the ejector includes a working inlet, an ejector inlet, and an ejector outlet. The nozzle of the ejector is arranged at the working inlet. The mixing chamber of the eductor may be located on a side of the nozzle of the eductor adjacent the eductor outlet. The mixing chamber may be connected between the receiving chamber and the diffusion chamber of the eductor.
The working inlet can be connected with a hydrogen source through an on-off valve. The on-off valve may be used to control whether the eductor is supplying hydrogen to the fuel cell. When the stack consumption of the fuel cell is relatively small, the supply amount of the pressure regulating valve is sufficient to supply hydrogen gas to the fuel cell. The on-off valve may be opened at this time, thereby controlling the ejector not to supply hydrogen gas to the fuel cell. As shown in FIG. 1, the outlet side of the pressure regulating valve may be provided with a pressure sensor P 1 . The inlet pressure corresponding to the operation condition of the fuel cell is set as the target pressure, and the outlet side pressure of the pressure sensor is controlled to be consistent with the target pressure, so that the opening of the pressure regulating valve can be regulated, and the hydrogen supply quantity on the inlet side of the fuel cell is ensured.
When the stack consumption of the fuel cell is relatively large, the amount of hydrogen required by the fuel cell gradually approaches the maximum supply capacity of the pressure regulating valve. The switch valve can be opened at the moment, so that the ejector is controlled to supply hydrogen to the fuel cell. Hydrogen from the hydrogen source may enter the eductor through the operational inlet of the eductor and be output to the fuel cell from the eductor outlet of the eductor. Excess hydrogen offgas from the fuel cell may be recycled through the ejector. The excessive hydrogen at the outlet of the fuel cell is driven by the high-pressure hydrogen flow at the working inlet, and the excessive hydrogen discharged by the fuel cell can enter the ejector through the ejection inlet. The hydrogen gas input from the bleed inlet may be mixed with the hydrogen gas input from the working inlet. The hydrogen mixed by the two can be output to the fuel cell through the outlet of the ejector. Thereby ensuring an excess factor of hydrogen circulation required by the stack. In some embodiments, the on-off valve may be a solenoid valve.
In some embodiments provided herein, the on-off valve can be opened when the stack consumption of the fuel cell is greater than the operational flow of the eductor. The principle of opening the on-off valve is described below. The stack consumption may generally correspond to the stack loading current of the fuel cell. The greater the stack consumption, the higher the stack loading current of the fuel cell. When the consumption of the galvanic pile is small, the hydrogen quantity required by the fuel cell is small, the working flow of the ejector exceeds the consumption of the galvanic pile, and the switch valve is closed at the moment. The flow rate at which the pressure regulating valve is opened can be controlled by controlling the outlet-side pressure of the pressure regulating valve.
And when the required hydrogen flow exceeds the minimum flow which is larger than the working flow of the ejector and larger than the regulating flow range of the pressure regulating valve, the switch valve is opened, and the ejector and the pressure regulating valve can cooperate to supply hydrogen to the fuel cell. Because the pressure at the working inlet side of the ejector can be kept constant through the primary pressure reducing valve, the working pressure of the ejector operates under the designed working pressure Pp in the full-operation working condition, the flow speed of the nozzle throat part of the ejector can reach the critical speed, the working flow of the ejector is constant, and constant partial consumption is provided for the galvanic pile. The ejector can provide ejection flow corresponding to the hydrogen excess coefficient which is not less than the electric pile in the operation range of the ejector. When the stack consumption of the fuel cell is at a relatively medium level, the opening degree of the pressure regulating valve can be relatively small, and hydrogen required by the fuel cell can be mainly provided by the ejector. Along with the gradual increase of the consumption of the fuel cell stack, the opening of the pressure regulating valve can be gradually increased due to the relatively limited working flow of the ejector so as to meet the hydrogen demand of the fuel cell.
In theory, the opening of the pressure regulating valve can be adjusted from zero. In practice, however, the adjustment accuracy of pressure control valves, in particular pressure control valves with relatively high operating pressures, is relatively poor around zero. In some embodiments, the control switch valve is opened when a difference between a stack consumption of the fuel cell and an operating flow of the ejector is greater than or equal to a minimum flow regulating value of the pressure regulating valve. Thus, when the stack consumption of the fuel cell continues to increase, the adjustment range of the pressure regulating valve is greater than the minimum flow adjustment value; when the fuel cell stack consumption continues to decrease, the switching valve is closed, and the adjustment range of the pressure regulating valve may also be greater than the minimum flow adjustment value. High-precision flow regulation can be achieved. In one possible case, the minimum flow rate setting value of the pressure regulating valve can be adapted to the operating flow rate capability of the ejector. When Q is consumed > 1.1Q P ～1.2Q P When the fuel cell is started, the switch valve is opened, wherein the consumption of Q is the consumption of the fuel cell stack, and Q P The working flow of the ejector. In this case, the pressure control valve is required to supply not less than 0.1Q to the fuel cell P ～0.2Q P The consumption exceeds the lowest flow value in the adjustable range of the pressure controller, and the control precision of the pressure controller is ensured.
In some embodiments provided herein, the gas supply circulation system may include a controller, and the gas supply circulation system may control opening and closing of the on-off valve by the controller.
In the embodiment shown in FIG. 1, the gas supply circulation system may also include a gas-water separator. A gas-water separator may be connected between the fuel cell and the bleed inlet. When the switch valve is opened, the gas-water separator can perform gas-water separation on the hydrogen with water humidity discharged by the fuel cell, and the separated hydrogen can be injected and circulated by the injector and then enters the fuel cell again. To ensure hydrogen purity, the gas-water separator periodically tails off a small portion of the tail gas from the fuel cell. When the switch valve is turned off, the hydrogen not consumed by the fuel cell can be discharged to the atmosphere through the tail of the gas-water separator because the pressure regulating valve can provide excessive hydrogen for the fuel cell. In the embodiment that this application provided, the operating condition of gas-water separator can with the operating condition adaptation of ejector to make gas supply circulation system can be for fuel cell continuously stable hydrogen supply. In some embodiments, the operating state of the gas-water separator can be regulated by the controller.
If the structural design of the ejector is unreasonable, the ejection capacity of the ejector is possibly insufficient or even ineffective under some working conditions. Generally speaking, when the fuel cell stack consumption is the largest, the ejector is required to provide larger ejection flow, so that the ejector is designed according to the working condition corresponding to the largest stack consumption, and the ejection capacity of the ejector generally meets the requirement. However, this is not completely consistent with the actual situation.
Let the pressure at the exit side of the eductor be P c ，P c The port mixing pressure may be indicated. The injection coefficient of the injector can be mixed with the outlet mixed pressure P c In relation to P c -P h In which P is c -P h The effect is greater. P c -P h Can be used for representing the flow resistance generated by devices such as a fuel cell, a gas-water separator and the like. Suppose P c Invariable, P c -P h The larger the ejector, the poorer the ejector capacity. Suppose P c -P h Unchanged, P c The larger the ejector, the poorer the ejector capacity. .
Generally, as the stack operating power increases, P c The step-by-step settings are progressively maximized, being maximized at full power operation. Therefore, when the stack consumption is at a maximum, there is a possibility that the ejector capacity is insufficient.
P c -P h Can be used forSatisfies the following conditions:
P c -P h ＝ξ electric pile *(Q Consumption of +G h ) 2 /ρ Saturated wet hydrogen +ξ Gas-water separation *G h 2 /ρ Saturated wet hydrogen ，
In which ξ Electric pile Coefficient of flow resistance, ξ, produced for the galvanic pile Gas-water separation The flow resistance coefficients generated by gas-water separation can be all constant; g h The ejector flow rate (circulation rate of the fuel cell) of the ejector is at least not less than the circulation rate required by the fuel cell when the fuel cell operates under various working conditions; q Consumption of The consumption of the fuel cell under each working condition is increased along with the increase of the operation power; rho Saturated wet hydrogen The saturated wet hydrogen gas density increases with an increase in Pc. There is therefore a low-power regime, due to P C Small value therefore p Saturated wet hydrogen Is small. Although Q Consumption of Maximum at full stack power, but p Saturated wet hydrogen At low power, so P c -P h The maximum value may occur at stack low power conditions. Therefore, when the consumption of the stack is minimized, there is a possibility that the ejector capacity is insufficient.
Because of the injection capacity and P of the injector c And P c -P h Relatively, under the working condition that the consumption of the galvanic pile is relatively large, the consumption of the galvanic pile is slightly smaller than that of the galvanic pile under the full-power working condition, but the corresponding P is c -P h P greater than full power condition c -P h And the problem of insufficient ejector capacity can occur under the working condition that the consumption of the galvanic pile is relatively large (not maximum).
Because of the injection capacity and P of the injector c And P c -P h Relatively, under the working condition that the consumption of the galvanic pile is relatively small, the consumption of the galvanic pile is slightly larger than that of the galvanic pile under the working condition of the lowest power, but the corresponding P is c -P h P greater than corresponding to lowest power condition c -P h The problem of insufficient ejector capacity may arise under conditions that result in relatively small (non-minimal) stack consumption.
In summary, the problem of insufficient ejector capacity may occur under any one of the conditions of maximum, minimum, large, small, etc. of the consumption of the stack. The problem that how to make the ejector that designs obtained injection ability satisfy required all operating mode requirements makes the ejector have bigger operating range is that needs to solve.
In order to solve the above problems, an embodiment of the present application provides a design process of an ejector. It is assumed that the gas supply circulation system can operate under N operating conditions. The following design flow may be for condition a of the N conditions.
1. Presetting the working fluid pressure P of the ejector p Pressure of the injection fluid P h And ejector working flow G P ＝G Minimum consumption -G Pressure regulating valve (ii) a Calculating the injection flow G of the injector h And (i-1), wherein Q is the consumption of the electric pile under the working condition A, and i is an excess coefficient.
The working fluid pressure P can be empirically determined p Initial setting is performed. Operating pressure P of the ejector p To ensure the expansion ratio (P) of the working fluid in the ejector P /P h ) The speed of the throat part of the nozzle is ensured to be not less than the critical speed; and cannot exceed the allowable inlet pressure range of the pressure regulating valve. The pressure can be selected to be low under the condition of meeting the requirements.
G Minimum consumption The lowest stack consumption at which the eductor is turned on for the gas supply circulation system corresponds to the lowest stack loading current for the fuel cell at which the eductor is turned on. G Minimum consumption Can reflect the operation range of the ejector. G Minimum consumption The larger the reactor consumption is, the larger the reactor consumption is when the ejector is opened, and the gas waste caused by the excessive gas needing to be discharged before the ejector is opened can be caused. G Pressure regulating valve The minimum flow regulating value of the pressure regulating valve is required to ensure that the precision of the flow controlled by the pressure regulating valve meets the required minimum flow.
2. And carrying out iterative calculation on the achievable injection coefficient u under the working condition A.
2.1,i =1, which is reachable under A conditionAssigning u to the injection coefficient u i ；
2.2 according to u i ＝G hi /G pi Calculating the ratio of working gas to injection gas, knowing the specific volume and gas adiabatic index of the working gas according to the corresponding pressure and temperature, and calculating v according to the ratio of the working gas to injection gas ci (specific volume of gas after mixing), k ci (post-mixing gas adiabatic index); v. of pi (specific volume of working gas), k pi (working gas adiabatic index) can be determined by the working fluid pressure P p Is calculated to obtain v Hi (specific injection gas volume), k Hi (injection gas adiabatic index) can be determined by injection fluid pressure P h And (4) calculating.
2.3, define i = i +1;
2.4, calculating the injection coefficient u according to a formula i ：
Figure BDA0003815667310000111
Figure BDA0003815667310000112
Figure BDA0003815667310000113
Figure BDA0003815667310000114
Coefficient of velocity of nozzle
Figure BDA0003815667310000115
Velocity coefficient of mixing chamber
Figure BDA0003815667310000116
Velocity coefficient of diffuser
Figure BDA0003815667310000117
Coefficient of velocity of the inlet section of the mixing chamber
Figure BDA0003815667310000118
P c -P h ＝ξ Electric pile *(Q Consumption of +G h ) 2 /ρ Saturated wet hydrogen +ξ Gas-water separation *G h 2 /ρ Saturated wet hydrogen ；λ pH For injecting the reduced isentropic velocity of the gas at a certain interface, according to II PH ＝p H /p p Looking up a gas dynamic function table in air and gas dynamics foundation to obtain a reduced isentropic speed; n =1.01 to 1.08.
2.5, judge | u i -u i-1 If u ≦ u 'holds, u' may be 0 or a value close to 0, such as 0.1,0.01, and the like. If so, determining ui as the achievable injection coefficient u of the working condition A; if not, step 2.2 is performed.
3. Judging U according to the U obtained in the step 2<U is established or not, wherein U is the design injection coefficient of the injector under the working condition A, and U = G h /G P . If so, determining the design injection coefficient U of the injector under the working condition A, and presetting the injector working flow G in the step 1 P And working fluid pressure P p And the design requirements are met. If not, adjusting the working flow G of the ejector P And/or working fluid pressure P p Up to U<And u is established, and finally the design injection coefficient of the injector under the working condition A is determined. Without changing the working-fluid pressure P p By increasing the ejector working flow G P And the design injection coefficient U of the injector under the working condition A can be reduced. Without changing the working flow G of the ejector P By increasing the working fluid pressure P p The injection coefficient u can be increased under the working condition A. If the working fluid pressure P P When the pressure reaches the allowable inlet pressure range of the pressure regulating valve, U is less than U, and the working flow G of the ejector can be increased P And the loading current corresponding to the galvanic pile when the ejector is opened is increased.
4. And designing each structure of the ejector according to the determined design ejector coefficient U, and referring to fig. 3 specifically.
4.1 nozzle throat diameter of ejector
Figure BDA0003815667310000121
Figure BDA0003815667310000122
Figure BDA0003815667310000123
Critical area of the nozzle throat;
Figure BDA0003815667310000124
4.2 nozzle opening diameter d of ejector p1
Figure BDA0003815667310000131
Figure BDA0003815667310000139
q p1 Only with expansion ratio (P) P /P h ) In correlation, the table look-up of the gas dynamic function table in the air and gas dynamic foundation can be obtained by looking up the table on the gas dynamic table, and the higher the expansion ratio is, the smaller qp1 is. In some embodiments, the minimum P may be based on the full operating range P /P h A value is selected. Therefore, a large amount of loss caused by excessive expansion of gas can not occur in the full working condition range.
4.3 diameter d of the mixing chamber of the ejector 3
Figure BDA0003815667310000132
|f p3 -f 3 The | is less than or equal to a preset threshold value;
Figure BDA0003815667310000133
Figure BDA0003815667310000134
Figure BDA0003815667310000135
Figure BDA0003815667310000136
according to II PH ＝p H /p p Looking up the chart of the aerodynamic function of gas in the foundation of air and gas dynamics pH 、q pH 。
4.4 distance l of ejector nozzle from mixing chamber c
Calculating d 4 ＝1.55d p1 (1+u)；
When d is 3 ＞d 4 When l is turned on c ＝l c1 ，
Figure BDA0003815667310000137
l c1 Is the length of the free stream at the nozzle outlet, j is the experimental constant;
when d is 3 ＜d 4 When l is turned on c ＝l c1 +l c2 ，
Figure BDA0003815667310000138
l c2 For the length of the mixing chamber inlet section, β is the cone angle of the mixing chamber inlet section, with reference to fig. 3, β = γ/2.tg is the tangent function.
4.5 ejector mixing Chamber Length l K Is 6 to 10 times of the diameter d of the mixing chamber 3 。
4.6 diameter d of injection inlet h Diameter d of the outlet of the ejector c The range is selected according to the diameter of the connected pipeline. The remaining parameters can be adjusted according to the dimensional requirements of the installed system.
In the embodiment provided above, the ejector designed according to the working condition a should meet the requirements of ejection capability under other working conditions among N working conditions. Through the design of the design flow, after the design injection coefficient of the injector under the working condition A is obtained, the design injection coefficient can be usedBased on the method, design injection coefficients U corresponding to other working conditions in the N working conditions in sequence are calculated 2 ……U N . In addition, an ejector designed on the basis of the working condition A can be determined through an experimental or simulation method, and the actual ejection coefficients U 'sequentially corresponding to the ejector in other working conditions in the N working conditions' 2 ……U’ N . If U is present 2 <U’ 2 ，……，U N <U’ N And the ejector can meet the use requirement under all working conditions.
When the number of the N working conditions is relatively large, the N working conditions are sequentially verified, which may result in an excessively large calculation amount. The embodiment of the application provides another kind of design flow of ejector, can obtain the ejector that satisfies full operating mode operation requirement through single design.
It is assumed that the gas supply circulation system can operate under N operating conditions.
1. Presetting the working fluid pressure P of the ejector p And the pressure P of the ejection fluid h And ejector working flow G P ＝G Minimum consumption -G Pressure regulating valve . Reference may be made specifically to step 1 above.
2. Referring to the step 2, the reachable injection coefficients u corresponding to the N working conditions are calculated 1 ……u N And from u 1 ……u N In finding the minimum u min Will minimize u min The corresponding working condition is the target working condition, and the minimum value u min The ejection coefficient can be achieved for the target corresponding to the target working condition.
3. U obtained according to step 2 min Judging U is less than or equal to U min Whether the conditions are satisfied or not, wherein U is the design injection coefficient of the injector, and U = G h /G P Injection flow rate G h And (i-1), wherein Q is the maximum electric pile consumption of the full working condition (namely the electric pile consumption required when the electric pile runs at full power), and i is an excess coefficient.
If so, determining the design injection coefficient U of the injector, and the preset injector working flow G in the step 1 P And working fluid pressure P p And the design requirements are met. If not, the ejector working flow is adjustedQuantity G P And/or working fluid pressure P p Until U is less than or equal to U min And finally determining the design injection coefficient of the injector. Reference may be made to step 3 above.
4. And designing each structure of the ejector according to the determined design ejector coefficient U. Specific embodiments may refer to step 4 above.
Through the second design mode that this application provided, can draw the ability comparison to full operating mode, guarantee that can reach in the full operating condition scope and draw the injection coefficient and all be greater than the design value, guarantee when full operating mode operation, compression ratio (P) can not appear c /P h ) Too high results in the problem of a reduction in the achievable ejection coefficient and even a negative number. Ejector working pressure P p May be constant.
For the ejector with the fixed size, when the ejector runs at a designed working condition point, the ejector flow can be ensured to meet the requirement of the hydrogen circulation amount of the galvanic pile. When the working flow is deviated from the design working condition, the injection coefficient is larger than the design working condition point due to the constant working flow, the injection coefficient can be calculated according to the ejector, and the injection coefficient can be higher than the design working condition point. Because not the optimum design size leads to the ejector at the scope increase of deviating from the design operating mode, the loss can increase, leads to actually reaching to draw the coefficient and deviate to calculate that draw the coefficient is big, still can be higher than the actual of design operating mode point and can reach and draw the coefficient, guarantees to draw the discharge and be no less than the design operating mode point when other operating modes are operated. The ejector designed and obtained through the second design mode can have better ejection capacity.
Although the present application has been described with reference to the preferred embodiments, it is not intended to limit the present application, and those skilled in the art can make variations and modifications without departing from the spirit and scope of the present application, therefore, the scope of the present application should be determined by the claims that follow.

Claims (11)

1. An eductor for use in a gas supply circulation system comprising:
a fuel cell;
a target gas source for supplying a target gas to the fuel cell;
the pressure regulating valve and the ejector are connected in parallel between the fuel cell and the target gas source;
the ejector comprises a working inlet, an ejector inlet and an ejector outlet, the working inlet is connected with the target gas source, the target gas exhausted by the fuel cell enters the ejector through the ejector inlet and is mixed with the target gas input by the working inlet, and the mixed target gas is output to the fuel cell through the ejector outlet;
the ejector is applied to N operating modes, and the ejector meets the following requirements:
under a target working condition in the N working conditions, the design injection coefficient of the injector is smaller than the reachable injection coefficient corresponding to the target working condition,
and under other working conditions in the N working conditions, the actual injection coefficient of the working condition of the ejector is not less than the designed injection system corresponding to the working condition of the ejector.
2. The ejector according to claim 1, wherein the N operating conditions correspond one-to-one to N achievable ejection coefficients, and the achievable ejection coefficient corresponding to the target operating condition is the minimum value of the N achievable ejection coefficients.
3. The eductor as defined in claim 1 wherein said design eductor coefficient is U = G h /G P The injection flow G of the ejector h = Qx (i-1), the ejector working flow G P ＝G Minimum consumption -G Pressure regulating valve Q is the maximum electric pile consumption or the electric pile consumption under the working condition corresponding to the designed injection coefficient, i is the excess coefficient, G Minimum consumption Minimum stack consumption when opening the eductor for gas supply cycle system, G Pressure regulating valve Is that it isMinimum flow adjustment value of the pressure regulating valve.
4. The eductor as defined in claim 1, wherein said achievable eductor coefficient u satisfies:
Figure FDA0003815667300000021
Figure FDA0003815667300000022
Figure FDA0003815667300000023
coefficient of velocity of nozzle
Figure FDA0003815667300000024
Velocity coefficient of mixing chamber
Figure FDA0003815667300000025
Velocity coefficient of diffuser
Figure FDA0003815667300000026
Coefficient of velocity of the inlet section of the mixing chamber
Figure FDA0003815667300000027
Δp c ＝p c -p H ；P c -P h ＝ξ Electric pile *(Q Consumption of +G h ) 2 /ρ Saturated wet hydrogen +ξ Gas-water separation *G h 2 /ρ Saturated wet hydrogen ；
υ p Is the specific volume of the working gas; upsilon is H Injecting specific gas volume; upsilon is c The specific volume of the mixed gas;
p p is the working gas pressure; p is a radical of H Injecting gas pressure; p is a radical of c Is the mixed gas pressure;
k p is the working gas adiabatic index; k is a radical of H Is the injection gas adiabatic index; k is a radical of c Is the adiabatic index of the mixed gas;
λ pH is a reduced isentropic velocity; n =1.01 to 1.08.
5. The injector according to any one of claims 1 to 4, wherein the injector has a working gas pressure P at which the stack consumption is at a maximum p And injection gas pressure P h Satisfies the following conditions:
expansion ratio P of working gas in the ejector P /P h Greater than the critical pressure ratio.
6. The eductor as claimed in any one of claims 1 to 4 wherein the eductor nozzle throat diameter
Figure FDA0003815667300000028
Is the critical area of the nozzle throat;
Figure FDA0003815667300000031
7. the eductor as claimed in claim 6 wherein the eductor nozzle opening diameter
Figure FDA0003815667300000032
f p1 ＝f p* /q p1 ，q p1 And the expansion ratio P in the N working conditions P /P h The minimum value in (1) corresponds to.
8. The eductor as defined in claim 7 wherein the diameter of the eductor mixing chamber
Figure FDA0003815667300000033
|f p3 -f 3 The | < a preset threshold value;
Figure FDA0003815667300000034
Figure FDA0003815667300000035
Figure FDA0003815667300000036
9. the eductor as claimed in claim 8 wherein d is 4 ＝1.55d p1 (1+u) distance l of the ejector nozzle from the mixing chamber c Satisfies the following conditions:
when d is 3 ＞d 4 When l is turned on c ＝l c1 ，
Figure FDA0003815667300000037
l c1 Is the length of the free stream at the nozzle outlet, j is the experimental constant;
when d is 3 ＜d 4 When l is turned on c ＝l c1 +l c2 ，
Figure FDA0003815667300000038
l c2 For the length of the mixing chamber inlet section, β is the cone angle of the mixing chamber inlet section.
10. The eductor as claimed in claim 8 or claim 9 wherein the length/' of the eductor mixing chamber K Is 6 to 10 times of the diameter d of the mixing chamber 3 。
11. A gas supply circulation system, comprising:
a fuel cell;
a target gas source for supplying a target gas to the fuel cell;
a pressure regulating valve and the eductor of any one of claims 1 to 10 connected in parallel between the fuel cell and the target gas source;
the ejector comprises a working inlet, an ejector inlet and an ejector outlet, the working inlet is connected with the target gas source, target gas exhausted by the fuel cell enters the ejector through the ejector inlet and is mixed with the target gas input by the working inlet, and the mixed target gas is output to the fuel cell through the ejector outlet.
CN202211026078.1A 2022-08-25 2022-08-25 Ejector and gas supply circulating system for fuel cell Pending CN115425255A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116525879A (en) * 2023-04-19 2023-08-01 江苏申氢宸科技有限公司 High-power fuel cell hydrogen supply circulation system and method

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116525879A (en) * 2023-04-19 2023-08-01 江苏申氢宸科技有限公司 High-power fuel cell hydrogen supply circulation system and method
CN116525879B (en) * 2023-04-19 2024-02-02 江苏申氢宸科技有限公司 High-power fuel cell hydrogen supply circulation system and method

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