EP1417724A1 - Systemes de piles a combustible avec regulation de la pression ou du flux volumique du gaz de reaction et alimentation/elimination du fluide de fonctionnement faisant intervenir un flux volumique de gaz de reaction - Google Patents

Systemes de piles a combustible avec regulation de la pression ou du flux volumique du gaz de reaction et alimentation/elimination du fluide de fonctionnement faisant intervenir un flux volumique de gaz de reaction

Info

Publication number
EP1417724A1
EP1417724A1 EP02794593A EP02794593A EP1417724A1 EP 1417724 A1 EP1417724 A1 EP 1417724A1 EP 02794593 A EP02794593 A EP 02794593A EP 02794593 A EP02794593 A EP 02794593A EP 1417724 A1 EP1417724 A1 EP 1417724A1
Authority
EP
European Patent Office
Prior art keywords
reaction gas
pressure
fuel cell
gas supply
low
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP02794593A
Other languages
German (de)
English (en)
Inventor
Florian Weber
Stefan Litzka
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Proton Motor Fuel Cell GmbH
Original Assignee
Proton Motor Fuel Cell GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Proton Motor Fuel Cell GmbH filed Critical Proton Motor Fuel Cell GmbH
Priority to EP02794593A priority Critical patent/EP1417724A1/fr
Publication of EP1417724A1 publication Critical patent/EP1417724A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • 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

Definitions

  • Fuel cell systems supply electrical consumers with electrical power.
  • the electrical power that can be obtained from the fuel cell system depends on the one hand on the structural design of the fuel cell system, that is, above all on the number and size of the individual fuel cells or the fuel cell stack, and on the other hand on the operating conditions. These primarily include reaction gas pressures or volume flows, operating temperature and water balance in the fuel cells.
  • the design of the fuel cell system determines the maximum performance that can be achieved.
  • the power that can actually be drawn by an electrical consumer at a specific time varies depending on the operating conditions. If the electrical consumer has high performance requirements, the volume flow to be supplied to the fuel cells must be increased up to the theoretically possible maximum value.
  • the fuel cells In order to achieve maximum efficiency, the fuel cells must be kept at an optimal moisture content.
  • the membranes of polymer electrolyte membrane fuel cells must always have a high water content in order to ensure good proton conductivity, since otherwise the fuel cell performance drops. However, if there is too much water in the fuel cells, the electrodes will flood and the achievable performance will also decrease.
  • reaction gas volume flows of the supplying fuel cell system are also subject to the same fluctuations.
  • this gas volume flow must often be able to be regulated or adjusted in the range of a few milliseconds in order to prevent unacceptable pressure overshoots or pressure undershoots in the system to avoid.
  • Piston or diaphragm pressure reducers are currently usually used for pressure control, but are unsatisfactory in terms of volume capacity, pressure accuracy, pressure reproducibility and control speed in applications that require rapid changes in the reaction gas volume flow, and are also large and heavy. The latter has a disadvantageous effect in particular in mobile applications, such as in a motor vehicle.
  • water is formed on the cathode side in fuel cells.
  • This water and any excess membrane dampening water and / or cooling water must be removed from the fuel cells in order to prevent the electrodes from flooding.
  • expelling water from the fuel cells e.g. the mutual charging of the fuel cells with gas in order to achieve an expulsion of water droplets by changing flow conditions.
  • the equipment required consists of one or more valves for gas flow deflection and the necessary control electronics.
  • Another possibility is to cyclically flush the cell with gas (reaction gas) into the environment. Valves and control elements are also required for this.
  • the loss of gas sometimes leads to a drastic deterioration in the overall efficiency of the fuel cell system.
  • the object of the present invention is therefore to provide a method for regulating the pressure of a reaction gas in a fuel cell system, which allows the reaction gas pressure to be regulated with high accuracy and to avoid pressure fluctuations in the system even in the case of rapid changes in volume flow.
  • the object of the present invention is also to provide a fuel cell system which is designed for the method according to the invention for regulating the pressure.
  • Another object of the present invention is to provide a fuel cell system which is designed for the humidification method according to the invention.
  • Another object of the present invention is to provide a fuel cell system which is designed for the method for expelling water.
  • the object is achieved by the fuel cell system according to claim 1 and the method for regulating the pressure according to claim 13.
  • the object is further achieved by the fuel cell system according to claim 19 and the method for dispersing water in a reaction gas according to claim 22.
  • the object is also achieved by the fuel cell power system and the method for adapting the power of a fuel cell power system to changing power requirements of an electrical consumer according to claims 24 and 26.
  • the fuel cell system preferably polymer electrolyte membrane / fuel cell system, has the following features: at least one fuel cell stack, a reaction gas supply with a high pressure area and a low pressure area to the fuel cell stack, - a device for controlling the pressure in the Low pressure area of the reaction gas supply with a clocked reaction gas inlet valve, ie a two-position reaction gas inlet valve of the type; a measuring point for measuring the pressure or a pressure-correlated measured variable in the low pressure range of the reaction gas
  • a control and regulating unit for recording and evaluating the pressure or the pressure-correlated measured variable and for controlling the reaction gas inlet valve depending on the pressure or the pressure-correlated measured variable.
  • a fuel cell stack typically has about 5 to 60 fuel cells, although the number can vary within a wide range, and the fuel cell system can have only one or a very large number of fuel cell stacks. In principle, however, the invention can be used for any number of individual fuel cells, for example also for only one individual fuel cell, or for any number of fuel cell stacks.
  • the reaction gas inlet valve is preferably arranged such that it separates the high pressure area and that of the reaction gas supply. If the valve is closed, the fuel cell system is also sealed off from the environment. A separate shut-off valve is not necessary because the reaction gas inlet valve also acts as a shut-off valve.
  • the pressure in the high pressure area is typically up to 200 bar, but can also be higher. As a rule, however, it is below this, for example up to 50 bar, typically about 5 bar.
  • the pressure in the low pressure area of the fuel cell system is system-dependent and is typically in the range from 180 a few 100 mbar to a few bar. A common pressure is about 2 bar.
  • a reaction gas pressure or a pressure-correlated measured variable is regulated.
  • Pressure-correlated measurement variables are, for example, the reaction gas volume flow or the partial pressure of the reaction gas.
  • the invention is described below on the basis of the measurement of the reaction gas pressure in the low pressure range, but this should not be understood as a limitation of the invention.
  • the measurement of pressure-correlated measured variables and activation of the reaction gas inlet valve depending on the measured value of the pressure-correlated measured variable represents an equivalent alternative.
  • the reaction gas is the fuel gas, e.g. Hydrogen
  • the control according to the invention can be carried out, provided the oxidant is supplied under pressure.
  • the pressure and / or volume flow control according to the invention comprises the following steps: continuous or regular measurement of the pressure or a pressure-correlated measurement variable in the low-pressure region of the reaction gas supply,
  • the measurement is carried out using conventional sensors known to those skilled in the art for this purpose.
  • the measured value of the, for example, reaction gas pressure is recorded by a conventional control and regulation unit and compared with the predetermined target value.
  • the actual value drops below the target value of the pressure or the pressure-correlated measured variable
  • a too low value is measured. If the measured value is too low, it is increased by an increased admission of reaction gas, that is to say an increase in the reaction gas volume flow flowing through the reaction gas inlet valve per unit of time. This is done by a suitable control of the clocked reaction gas inlet valve. However, if the measured value is too high, it will
  • reaction gas inlet valve 225 by a reduced admission of reaction gas, that is to say by a reduction in the reaction gas volume flow flowing through the reaction gas inlet valve per unit of time. This is also done by a suitable control of the reaction gas inlet valve.
  • the regulation of the reaction gas volume flow flowing through the clocked reaction gas inlet valve per unit of time into the low pressure range is preferably carried out by pulse-modulated or frequency-modulated control of the reaction gas inlet valve.
  • a two-point controller is used as the control and regulating unit for the pulse-modulated control, and a for the frequency-modulated control
  • pulse times in which the reaction gas inlet valve is open alternate with pause times in which the reaction gas inlet valve is closed.
  • a constant reaction gas volume flows during the pulse times.
  • reaction gas volume flow flowing through the reaction gas inlet valve per unit of time is greater, the longer the pulse times and accordingly the shorter the remaining pause times.
  • the reaction gas volume flow is varied here by suitable variation
  • the pulse times during which the reaction gas inlet valve is open and a constant reaction gas volume flow flows into the 250 fuel cell system are constant.
  • the pause time between two pulse times is varied, in which the valve is closed and no reaction gas can flow in.
  • a reaction gas outlet valve can be provided in the low-pressure area of the reaction gas supply, which can also be controlled by the control and regulating unit as a function of the pressure or the pressure-correlated measured variable.
  • the reaction gas outlet valve enables a considerably faster pressure reduction in the low pressure range than this by simply keeping the reaction gas inlet valve closed while simultaneously consuming reaction gas through the fuel cells, so it essentially has a safety function.
  • the reaction gas outlet valve can be any valve, for example a continuously controllable valve or a clocked valve such as the reaction gas inlet valve.
  • the control can take place, for example, in such a way that a certain limit value of the pressure in the low pressure range is specified, which may not be exceeded. Should it still be exceeded, the reaction gas outlet valve is activated and opened until the limit is undershot.
  • the reaction gas inlet valve is a valve that has very short switching times. Solenoid valves and piezo valves are preferred which, on the one hand, react very quickly and, on the other hand, only have two switch positions, so that when the valve is opened the maximum possible amount of gas can flow through the valve, with this amount of gas flowing until the valve closes.
  • the accuracy and reproducibility of the pressure setting does not depend on the inertia of the valve, but only on the inertia of the control loop elements used in the system. Since the control and regulation takes place electronically, i.e. without inertia, the pressure is also set very quickly.
  • the low-pressure region of the reaction gas supply can be designed as a distributor line for reaction gas, which leads the reaction gas to the fuel cell stacks and finally to the individual fuel cells.
  • the low-pressure area can also be designed as a low-pressure space, from which all individual fuel cells of a stack are supplied with reaction gas.
  • the low-pressure space can be the anode space of a fuel cell stack, from which fuel gas flows into the individual fuel cells of the stack.
  • the reaction gas inlet valve can be integrated 290 into the reaction gas supply such that its drive is also accommodated in the reaction gas supply. This has the advantage that no additional sealing systems are required.
  • the integrated installation is possible both in the high-pressure area and in the low-pressure area of the reaction gas supply, the low-pressure area being able to be designed both as a distributor line and as a low-pressure space. Is the low 295 pressure area formed as a low pressure space, the reaction gas inlet valve separates the high pressure area from the low pressure space of the fuel cell stack.
  • each low-pressure chamber of a fuel cell stack preferably has a reaction gas inlet valve which separates the low-pressure chamber of the fuel cell stack in question
  • a reaction gas inlet valve can also be integrated directly on each fuel cell stack.
  • the distribution line represents the high-pressure area, and, as with the variant with low-pressure space, there is a separate control and regulating unit for the respective reaction gas inlet for each fuel cell stack.
  • the reaction gas inlet valve separates the high pressure area from the low pressure area of a fuel cell stack.
  • the reaction gas inlet valve can also be integrated in such a way that it opens the reaction gas supply for several or all fuel cell stacks together upstream from a low-pressure region (distributor line) common to all fuel cell stacks.
  • reaction gas outlet valve including the drive can also be easily inserted into the reaction gas supply, e.g. in a low pressure room, so that no additional sealing systems are required.
  • a fuel cell system with a piezo valve as a reaction gas inlet valve is particularly suitable, with a low pressure chamber as a low pressure area of the reaction gas
  • the system is particularly simple to set up with a high power density. Even if it is an ideal solution especially for miniaturized gas supply systems, it is by no means restricted to this area of application, but can also be used in any other
  • Fuel cell systems with pressure control according to the invention have a number of advantages over fuel cell systems with conventional pressure control: they allow extremely fast, precise and reproducible pressure control
  • reaction gas in the low pressure area of the fuel cell system can be provided for supply at low pressures, and this reaction gas volume flow can be opened and closed almost without inertia in order to avoid impermissible pressure overshoots or pressure undershoots in the fuel cell system. Even if
  • the fuel cell system according to the invention has a reaction gas supply
  • throttle device which separates the high pressure region and the low pressure region of the reaction gas supply during operation of the fuel cell system, and an upstream from the throttle device or directly into the throttle device opening into the reaction gas supply Water supply on.
  • 355 is, for example, a nozzle or an aperture, preferably a convergent nozzle.
  • the arrangement of the throttle device such that it separates the high-pressure region and the low-pressure region of the reaction gas feed means that the upstream inlet of the throttle device is at a high pressure level. 360 veau pi and the downstream outlet of the throttle device at a lower pressure level p.
  • the flowing reaction gas enters the throttle device at a pressure p1 and is expanded to the pressure of the low-pressure region p2 when it leaves the throttle device.
  • the reaction gas pressure is preferably at least equal to the critical one
  • water is in the high-pressure region of the reaction gas supply between reaction gas inlet valve and inlet of the throttle device or in
  • 390 droplets i.e. to disperse the water in the reaction gas.
  • the dispersion is generally carried out more thoroughly the greater the difference between the narrowest cross section of the throttle device and the pressure after the nozzle.
  • the water entrained in the reaction gas forms a spray cone when it emerges from the throttle device.
  • the humidification 395 tion water is now dispersed in the flowing reaction gas and is distributed by it very evenly to all individual fuel cells of the fuel cell stack or the fuel cell stack. The membranes of all individual fuel cells are moistened very evenly.
  • the dispersed water can also partially evaporate in the reaction gas and thus lead to cooling of the fuel cells.
  • the metering is preferably carried out via a pump from a water reservoir.
  • the process according to the invention for dispersing water in a reaction gas can be used for any reaction gas which is supplied under pressure. It is independent of the type of reaction gas inlet valve used and the type of pressure control in the low pressure range, so it can be used to advantage in any 415 fuel cell system.
  • dispersing water according to the invention in a reaction gas in fuel cell systems which have one or more of the features described above in connection with the pressure control 420 according to the invention, or to combine the method for dispersing water with process features as described above for the method for pressure control according to the invention.
  • the throttle device is particularly advantageous to provide the throttle device after a clocked reaction gas inlet valve, not after a continuously regulating reaction gas inlet valve.
  • the clocked reaction gas inlet valve always has the same fluid mechanics during the opening time of the valve Conditions under which the system can be optimized with regard to the efficiency of the atomization and distribution of the water.
  • polymer electrolyte membrane fuel cells have to be moistened in order to always ensure optimum conductivity of the polymer electrolyte membrane, on the other hand, however, water also arises during the fuel cell reaction, which must be removed from the fuel cells in order to flood the electrodes
  • the removal of excess water from the fuel cell system is achieved by utilizing the kinetic energy contained in the reaction gas volume flow.
  • the fuel cell system in a reaction gas supply to the fuel cell stack or the fuel cell stacks has a gas jet with a driving nozzle, inlet to the gas
  • reaction gas recirculation opens into the inlet for gas intake of the gas emitter.
  • the reaction gas recirculation is advantageously designed as a manifold for unused reaction gas from the fuel cells.
  • reaction gas is passed through any reaction gas inlet valve as a propellant jet through the gas jet, which the high pressure area and the low pressure
  • reaction gas 450 separates the pressure range of the reaction gas supply, fed into the reaction gas supply and passes the fuel cell stack or the fuel cell stack. Unused reaction gas is fed back into the gas jet by a reaction gas return, a pressure which is lower than that being generated in the reaction gas return by the suction effect of the gas jet
  • a water separator is preferably provided in the reaction gas recirculation in order to prevent the sucked-in water from entering the gas jet and thus the reaction gas supply.
  • the gas jet separates the high-pressure area and the low-pressure area of the fuel cell system and can thus use the entire pressure energy contained in the inflowing reaction gas volume flow for gas suction, whereby theoretically an absolute vacuum can be achieved.
  • the fuel cell system with gas jet for vacuum generation in the reaction gas return is rather simple and compact in structure and maintenance-free.
  • a particular advantage lies in the synchrony between fuel cell performance and water removal efficiency. With higher performance of the fuel cell system, a higher reaction gas volume flow is required.
  • Another advantage of this system is that it enables the fuel cells to operate in an open, continuous flow without gas loss, because unused reaction gas is mixed with the newly supplied reaction gas in the gas emitter and used again.
  • reaction gas inlet valve is a pulsed valve, such as a solenoid valve or 495 a piezo valve
  • the maximum reaction gas volume flow flows in when the valve is open, so that full pressure is applied to the downstream gas jet when the valve is open.
  • the gas jet can therefore always be operated at optimum operating performance and provide its maximum suction power.
  • the specified water expulsion from the fuel cells can also advantageously be combined with the dispersion of water in a reaction gas according to the invention, regardless of the type of pressure control.
  • the driving nozzle of the gas jet acts as a throttle device, and the dampening water is fed upstream from the driving nozzle or in the driving nozzle into the reaction gas supply.
  • the water supplied increases the motive mass flow and therefore leads to an improvement in the vacuum which can be achieved in the reaction gas recirculation.
  • pressure control for dispersing water in a reaction gas volume flow and for expelling excess water from the fuel cells can also be implemented together in a single system.
  • Such a fuel cell system allows pressure fluctuations in the low-pressure region of the fuel, even with rapidly changing reaction gas volume flows.
  • the fuel cells can be moistened under the conditions of constant oversupply with water and thus guaranteed optimal moistening of the membranes.
  • a change in the electrical power to be supplied by a fuel cell power system as is required when changing the power requirements of an electrical consumer, for example a motor vehicle traveling at changing speeds, requires a change in the
  • reaction gas volume flow 530 supplying reaction gas volume flow.
  • this is achieved by supplying the fuel cells with a certain amount of reaction gas, which is dependent on the desired output of the electrical consumer.
  • reaction gas inlet valve which can be a clocked valve or a continuously regulating valve.
  • the pressure is regulated by power electronics in such a way that the fuel cells always have so much electrical power
  • a fuel cell power system according to the invention which is designed for variable power requirements of an electrical consumer, has:
  • 550 - at least one fuel cell stack, a consumer electrically connected to the fuel cell stack, a reaction gas supply to the fuel cell stack with a reaction gas inlet valve, a high pressure region and a low pressure region, a device for specifying a target value of a reaction gas Volume-
  • a device for detecting the target value of the reaction gas volume flow and for controlling the reaction gas inlet valve in accordance with the target value specification control unit
  • a measuring point for continuous or regular measurement of the pressure 560 or a pressure-correlated measured variable in the low-pressure area of the reaction gas supply a device for recording and evaluating the pressure or the pressure-correlated measured variable and for releasing the fuel cell output corresponding to the pressure or the pressure-correlated measured variable to the electrical Consumers (power controller)
  • power electronics for setting the target power of the electrical consumer
  • the target value specification for the reaction gas volume flow to be supplied takes place in each case
  • the specified target value is recorded by a control unit which controls the reaction gas inlet valve in accordance with the target value specification, i.e. the reaction gas inlet valve is opened as long as
  • the pressure or a pressure-correlated measured variable is measured continuously or regularly and recorded by a power controller.
  • the power controller compares the actual value of the pressure or the pressure
  • 585 fuel cell system takes the fuel cell power released by the power controller.
  • the desired power or another electrical quantity for example the voltage or the current
  • the fuel cell power system according to the invention 590 has a device for pre-setting a setpoint value for a reaction gas volume flow. would give a desired target value of the corresponding electrical quantity, and instead of the device for detecting the reaction gas volume flow and for controlling the reaction gas inlet valve according to the target value specification
  • the control unit 595 be it has a device for determining the actual value of the electrical variable and a device for comparing the determined actual value with the predetermined target value and for controlling the reaction gas inlet valve in accordance with the target value specification.
  • the actual value of the electrical quantity can be determined by the power electronics or another measuring device. In the control
  • the reaction gas inlet valve is controlled accordingly, i.e. the reaction gas inlet valve is opened when the target value is not reached and closed as long as it is reached.
  • FIG. 1 shows a fuel cell system with pressure control according to the invention and a low-pressure region of the reaction gas supply formed as a reaction gas distributor line,
  • FIG. 2 shows a fuel cell system with a fuel cell stack and with the pressure control according to the invention and a low-pressure area of the reaction gas supply designed as a low-pressure chamber
  • FIG. 3 shows a fuel cell system as in FIG. 2, but with two fuel cell stacks and associated low-pressure spaces,
  • FIG. 5 shows a schematic diagram for frequency-modulated reaction gas inlet valve control
  • FIG. 6 shows a partial area of a fuel cell system with water dispersion according to the invention in the reaction gas supply, 625
  • FIG. 7 shows a partial area of a fuel cell system with an arrangement for expelling water from the fuel cells
  • FIG. 8 shows a fuel cell system as in FIG. 1, but with an arrangement for expelling 630 water
  • FIG. 9 shows a partial area of a fuel cell system with a water dispersion according to the invention and an arrangement for expelling water
  • FIG. 10 shows a fuel cell power system according to the invention, which is designed for variable power requirements of an electrical consumer.
  • a reaction gas such as hydrogen, becomes the fuel cell system
  • the low-pressure region 6 of the reaction gas supply is designed as a distributor line which distributes the reaction gas to the individual fuel cell stacks and the individual fuel cells 3 which form the stacks.
  • a measuring point 9 for measuring the pressure of the reaction gas is located in the low pressure region 6 of the fuel cell system.
  • a pressure-correlated measurement variable can also be measured, for example the partial pressure of the reaction gas or the reaction gas volume.
  • the measured variable is recorded in a control and regulating unit 10 and the measured value is compared with the target value of the measured variable specified for the system. If the measured value is below the target value, the reaction gas inlet valve 8 or the drive 16 of the reaction gas inlet valve 8 is activated and the reaction gas inlet valve is opened, so that reaction gas from the
  • the reaction gas inlet valve 8 is a clocked valve, ie a valve with only two switching positions. Examples include a solenoid valve and a piezo valve.
  • the control of the Onsgas inlet valve can be pulse modulated as shown in FIG. 4 or frequency modulated as shown in FIG. 5. Is the measured at measuring point 9
  • the reaction gas inlet valve remains closed and is only opened again when the measured value drops below the target value of the system due to the consumption of reaction gas.
  • the system shown in FIG. 1 additionally has a
  • reaction gas outlet valve 11 is also controlled by the control and regulating unit 10. It can be a clocked valve such as the reaction gas inlet valve 8, or it can also be a continuously controlled valve.
  • the reaction gas outlet valve 11 is activated on
  • FIGS. 2 and 3 also show fuel cell systems with pressure control according to the invention.
  • the low-pressure region 6 of the reaction gas supply is designed as a gas space into which the reaction gas flows from the high-pressure region 5 when the inlet valve 8 is open.
  • the reaction gas flows from the gas space 6 into the reaction gas flow fields 14 of all individual fuel cells 3 of the
  • the reaction gas inlet valve 8 which separates the high-pressure region 5 from the low-pressure region 6, is accommodated together with its drive 16 in the low-pressure space, so that no separate sealing is required.
  • the low-pressure space 6 is arranged on a side surface of the fuel cell stack 2. On another side surface, in the embodiment shown on the
  • reaction gas flow fields 14 ' a space 18 is provided for the other reaction gas, from which this reaction gas flows into reaction gas flow fields 14 '.
  • the measurement of the reaction gas pressure or the pressure-correlated measured variable at the measuring point 9 and the actuation of the valve 8 via the actuation and control unit 10 is carried out as in FIG. 1.
  • no reaction gas outlet valve 11 is shown, but such a valve can of course also be provided in this embodiment.
  • FIG. 3 shows a fuel cell system 1 of the same type as shown in FIG. 2, but with two fuel cell stacks 2, 2 each of which has its own low-pressure space.
  • reaction gas inlet valves 8, 8' have a common high pressure area 5 of the reaction gas supply. It is also possible to have more than two fuel cell stacks, in which the low-pressure area of the reaction gas supply is designed as a low-pressure area, from a high-pressure area 5 with reaction
  • 700 gas can be supplied.
  • reaction gas inlet valve directly on the fuel cell stack and its integrated installation, i.e. Installation including drive, in the reaction gas supply is possible regardless of the presence of a low pressure chamber and also in the case of distribution lines.
  • the reaction gas inlet valve can both in
  • Fig. 4 shows the gas flow through a clocked valve such as the reaction gas inlet valve 8 with pulse-modulated control of the valve.
  • the basic sequence Ti der
  • pulse-modulated control is composed of a pulse time T 2 during which the valve is open and a pause time T 3 during which the valve is closed.
  • T 2 a pulse time during which the valve is open
  • T 3 a pause time during which the valve is closed.
  • FIG. 5 shows the gas flow through a clocked valve such as the reaction gas inlet valve 8 with frequency-modulated control of the valve.
  • the valve is ner control frequency 1 / T ⁇ controlled, where Ti is the sum of the pulse time T 2 (hatched in Fig. 5) and the pause time T 3 .
  • the valve is opened, and the maximum possible reaction gas volume flow flows through the valve into the low-pressure region of the reaction gas supply.
  • the valve is closed and no reaction gas can flow in.
  • the duration of the pulse times is constant, but the duration of the pause times is variable. 5 shows a control frequency with long pause times on the left,
  • the variant shown on the right therefore has significantly more control pulses per unit time of the valve.
  • the reaction gas volume flow flowing through the reaction gas inlet valve into the low pressure region of the reaction gas supply is therefore significantly higher in the case of frequency-modulated control according to the variant shown on the right than in the case of
  • FIG. 6 shows a partial area of a fuel cell system 1 with water according to the invention being dispersed in a reaction gas.
  • the partial area shown shows the path of a reaction gas up to the entry into the low-pressure area
  • reaction gas flows from the high pressure region 5 of the reaction gas supply through the reaction gas inlet valve 8 with the drive unit 16 into the region 5 ′ of the reaction gas supply and from there through a throttle device 20 into the low pressure region 6 of the reaction gas supply.
  • the area 5 ' is a loading
  • a water supply 21 opens into the reaction gas supply between the reaction gas inlet valve 8 and the throttle device 20.
  • the water supply 21 feeds water from a water reservoir 27 into the reaction gas supply by means of a pump 28.
  • the water fed in is shown schematically in FIG. 6 by drops.
  • the water feed can also be
  • the reaction gas Before passing through the throttling device 20, the reaction gas is at a pressure pi and after passing through the throttling device at a pressure p 2 that is less than pi. The reaction gas is thus released, a supercritical expansion being preferred, since it ensures a thorough distribution of the water carried by the reaction gas volume flow in the reaction gas volume flow in the form of very fine droplets (mist, aerosol).
  • the throttle device 20 is preferably designed in the form of a convergent nozzle such that the pressure of the reaction gas flowing through the throttle device is equal to the critical pressure at its narrowest cross section.
  • the reaction gas inlet valve is shown as a clocked valve.
  • a continuously regulating inlet valve can also be used, but the clocked valve has the advantage that, when open, the pressure pi in the region 5 'of the reaction gas supply is equal to the pressure in the high pressure region 5 of the reaction gas supply.
  • the reaction gas jet impinging on the throttle device 20 therefore has a very high pressure energy, which ensures very fine atomization and distribution of the water fed in after passing through the throttle device 20.
  • FIG. 7 shows a partial area of a fuel cell system 1 with an arrangement for expelling water, and the partial area shown shows the section of the reaction gas supply from the reaction gas inlet valve to the beginning of the low-pressure area of the reaction gas supply.
  • the reaction gas (represented by arrows) flows from the high pressure region 5 through the reaction gas inlet valve 8 with the drive unit 16 into the region 5 'of the reaction gas supply.
  • a gas jet 22 is provided between the area 5 'of the reaction gas supply and its low pressure area 6.
  • the gas jet is of conventional construction per se and has a driving nozzle 23, a catching nozzle 25, a gas outlet 29 and an inlet for gas suction 24.
  • the gas jet 22 is arranged in the reaction gas supply in such a way that its area 5 ′ into the driving nozzle 23 of the gas jet opens and the gas outlet 29 opens into the low-pressure area 6 of the reaction gas supply.
  • the reaction gas flowing through the gas jet 22 causes suction at the inlet to the gas intake 24, which is used to draw in excess gas. shot water from the fuel cells 3 can be used.
  • the fuel cells 3 or fuel cell stack 2 must be equipped with a reaction gas return 26, which opens into the inlet for the gas intake 24 of the gas emitter 22.
  • FIG. 8 shows a 795 fuel cell system 1, as shown in FIG. 1, but with gas jet 22 and reaction gas recirculation 26.
  • the returned reaction gas preferably passes through a water separator (not shown).
  • FIG. 9 shows the same arrangement as FIG. 7, but with a water supply 21 as shown in FIG. 6.
  • the driving nozzle 23 of the gas jet 22 takes over the function of the throttle device 20 in FIG. 6.
  • FIG. 10 shows a fuel cell power system according to the invention, which is designed for variable power requirements of an electrical consumer. The arrangement is identical to the fuel cell system shown in FIG. 1 with regard to the reaction gas supply with reaction gas inlet valve 8, high pressure region 5 and low pressure region 6, as well as with regard to measuring point 9 and fuel cell stack 2, 2 '.
  • a reaction gas outlet valve 11 as a safety valve is not shown in FIG. 10.
  • a setpoint value for a desired reaction gas volume flow or a setpoint value for the power to be supplied or another electrical variable, for example voltage or current, is specified by means of a device 31.
  • the setpoint value is recorded by a control unit 32 which controls the reaction gas inlet valve 8 in such a way that the specified reaction gas volume flow from the high pressure area 5 of the reaction gas supply into the low pressure area 6 of the reaction gas supply is fed.
  • the reaction gas pressure (or a pressure-correlated measured variable) is measured and recorded by a power controller 33, which compares the measured value with the predetermined target value of the system. With an increasing inflow of reaction gas into the low pressure area 6, the reaction gas pressure increases in this area.
  • the power controller 33 transmits a signal to the power electronics 34 connected to the electrical consumer 30 that fuel cell power can increasingly be drawn.
  • the power electronics 34 then adjust the power of the electrical consumer 30 so that enough electrical power is drawn from the fuel cells that the pressure in the low-pressure region 6 is kept constant.
  • this predetermined setpoint value is determined in the control unit 32 using the actual value of the electrical variable determined by the power electronics 34 or another suitable measuring device, e.g. by means of a standard controller. The result of the comparison is used to actuate the reaction gas inlet valve 8, which is actuated whenever the desired value is not reached.
  • the device and the method for dispersing water 860 in the reaction gas volume flow as well as the device and the method for expelling excess water each additionally have one or more of the features described for the pressure control, any combination of features being possible.
  • a method and a system with pressure control according to the invention in combination with the dispersion of water according to the invention and the removal of excess water are particularly preferred. Also a combination of dispersing water according to the invention in the reaction gas volume flow for moistening the fuel cells and expelling excess water
  • the fuel cells for regulating the water balance in conventional pressure control is advantageous.

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Fuel Cell (AREA)

Abstract

L'invention concerne un dispositif et un procédé permettant de maintenir constante la pression du gaz de réaction dans les piles à combustible d'un système de piles à combustible, même dans le cas de variations importantes du flux volumique de gaz de réaction ou de variations importantes de la puissance consommée par un récepteur électrique. La stabilité de pression est assurée par une soupape d'admission de gaz de réaction cadencée. L'invention concerne également des procédés et dispositifs de régulation de l'équilibre hydrique de systèmes de piles à combustible dans des conditions rendues difficiles par des variations imprévisibles de flux volumiques de gaz de réaction et de la puissance consommée par un récepteur électrique.
EP02794593A 2001-08-10 2002-08-09 Systemes de piles a combustible avec regulation de la pression ou du flux volumique du gaz de reaction et alimentation/elimination du fluide de fonctionnement faisant intervenir un flux volumique de gaz de reaction Withdrawn EP1417724A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP02794593A EP1417724A1 (fr) 2001-08-10 2002-08-09 Systemes de piles a combustible avec regulation de la pression ou du flux volumique du gaz de reaction et alimentation/elimination du fluide de fonctionnement faisant intervenir un flux volumique de gaz de reaction

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
EP01119341 2001-08-10
EP01119341 2001-08-10
EP02794593A EP1417724A1 (fr) 2001-08-10 2002-08-09 Systemes de piles a combustible avec regulation de la pression ou du flux volumique du gaz de reaction et alimentation/elimination du fluide de fonctionnement faisant intervenir un flux volumique de gaz de reaction
PCT/EP2002/008944 WO2003015202A1 (fr) 2001-08-10 2002-08-09 Systemes de piles a combustible avec regulation de la pression ou du flux volumique du gaz de reaction et alimentation/elimination du fluide de fonctionnement faisant intervenir un flux volumique de gaz de reaction

Publications (1)

Publication Number Publication Date
EP1417724A1 true EP1417724A1 (fr) 2004-05-12

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EP02794593A Withdrawn EP1417724A1 (fr) 2001-08-10 2002-08-09 Systemes de piles a combustible avec regulation de la pression ou du flux volumique du gaz de reaction et alimentation/elimination du fluide de fonctionnement faisant intervenir un flux volumique de gaz de reaction

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EP (1) EP1417724A1 (fr)
WO (1) WO2003015202A1 (fr)

Families Citing this family (7)

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Publication number Priority date Publication date Assignee Title
US7402353B2 (en) * 2004-04-13 2008-07-22 General Motors Corporation Transient controls to improve fuel cell performance and stack durability
US7662495B2 (en) 2004-11-05 2010-02-16 Gm Global Technologies Operations, Inc. Passive restriction pathways in fuel cell water drainage
DE102006060454A1 (de) 2006-12-19 2008-06-26 Masterflex Ag Brennstoffzellenanordnung und Verfahren zum Betreiben einer Brennstoffzelle
DE102009036435A1 (de) * 2009-08-06 2011-02-10 Daimler Ag Versorgungsanordnung für ein Brennstoffzellenpack, Brennstoffzellenmodul sowie Verfahren zum Betreiben des Brennstoffzellenmoduls
US9954235B2 (en) * 2014-12-22 2018-04-24 Intelligent Energy Limited Anode chambers with variable volumes
DE102019212307A1 (de) * 2019-08-16 2021-02-18 Robert Bosch Gmbh Brennstoffzellensystem und Verfahren zum Betrieb eines Brennstoffzellensystems
CN110531273A (zh) * 2019-09-30 2019-12-03 中国华能集团清洁能源技术研究院有限公司 一种高温燃料电池测试系统

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Publication number Priority date Publication date Assignee Title
US4729930A (en) * 1987-05-29 1988-03-08 International Fuel Cells Corporation Augmented air supply for fuel cell power plant during transient load increases
FR2712099B1 (fr) * 1993-11-02 1995-12-08 Imra Europe Sa Procédé de régulation de la pression d'un gaz dans une enceinte.
DE19643054C2 (de) * 1996-10-18 2003-02-27 Ballard Power Systems Ventil mit Laval-Düse und Verwendung desselben
US6042960A (en) * 1997-10-15 2000-03-28 Ergenics, Inc. Automatic water vapor density control of hydrogen gas
AT407314B (de) * 1998-11-23 2001-02-26 Vaillant Gmbh Brennstoffzellenanordnung

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