WO2008092545A1

WO2008092545A1 - Gas supply arrangement in a fuel cell apparatus

Info

Publication number: WO2008092545A1
Application number: PCT/EP2008/000066
Authority: WO
Inventors: Janusz Blaszczyk; Wolfram Fleck; Michael Procter; Darren Sokoloski
Original assignee: Daimler Ag; Ford Global Technologies, Llc
Priority date: 2007-01-30
Filing date: 2008-01-08
Publication date: 2008-08-07
Also published as: DE102007004590A1

Abstract

The invention, which relates to a gas supply arrangement in a fuel cell apparatus, having a jet pump arrangement for feeding a supply gas in a gas supply line using a propellant gas and having a control unit for controlling a supply gas volume flow, is based on the object of providing a gas supply arrangement for a fuel cell apparatus, which ensures that the supply gas is fed in a functionally reliable manner over the entire operating range of the fuel cell apparatus. The object is achieved in that the jet pump arrangement 9 has at least two jet pumps (10, 11) which are arranged connected in parallel in order to feed the supply gas in parallel, and can be controlled selectively by means of the control unit (17).

Description

Gas supply arrangement in a fuel cell apparatus

The invention relates to a gas supply arrangement in a fuel supply apparatus, having a jet pump arrangement for feeding a supply gas in a gas supply line using a propellant gas, and having a control unit for controlling a supply gas volume flow.

Fuel cell apparatuses are apparatuses which are used to produce electrical energy by means of an electrochemical process. The use of fuel cell apparatuses such as these is particularly attractive in vehicle design as an alterative energy and propulsion source to conventional internal combustion engines.

A fuel cell essentially comprises an anode with an anode area on an anode side, and a cathode with a cathode area on a cathode side, the anode side and cathode side being separated from one another by an electrolyte. During the electrochemical process in the fuel cell, a fuel which is held on the anode side, for example gaseous hydrogen, reacts with gaseous oxygen, which is held on the cathode side and generally originates from the surrounding air. The fuel is split into protons and electrons adjacent to the anode, with the electrons being passed to the cathode, during which process they carry out electrical or mechanical work using their electrical energy, while the protons are passed from the anode area through the electrolyte to the cathode area, where they react with the oxygen anions formed on the cathode side to produce water.

One fuel cell which is particularly suitable for use in vehicle design is the PEMFC (Proton Exchange Membrane Fuel Cell) , in which the electrolyte is formed by a proton- conducting polymer membrane. The combination of the anode area, cathode area and polymer membrane (membrane electrode arrangement MEA) requires particular gas supply and water management, and adequate moisturizing of the membrane, for effective operation of the fuel cell.

This together with the conditions which will be explained in the following text result in stringent requirements for the gas supply to the fuel cell arrangement with fuel and oxygen, in particular for the anode-side gas supply.

In a fuel cell apparatus, a multiplicity of fuel cells are typically combined to form one or more fuel cell stacks, in order to make it possible to produce the required power, for example, in order to drive a vehicle. External air, which contains the necessary proportion of oxygen, is generally fed through the cathode side of the fuel cell stack, as the cathode gas, with the cathode gas being compressed by means of a pump arrangement (compressor) , being accelerated and being supplied via a supply line to the cathode side. After passing through the cathode side, the air, together with the oxygen which has only partially been consumed, is either supplied in a closed circuit of a recirculation arrangement to the cathode side again, with fresh air being admixed with it, or it is emitted to the exterior via an exhaust gas line. The anode gas flows through the anode side of the fuel cell stack, by virtue of the feed pressure of a pump arrangement, and contains the gaseous fuel, preferably hydrogen, in which case the fuel is likewise not completely consumed as it passes through the anode side of the fuel cell stack. In order to increase the efficiency of the gas supply in the fuel cell apparatus, the anode gas is fed in a closed circuit of a recirculation arrangement, in which case the only partially consumed anode gas is supplied to the fuel cell stack again, and unconsumed fuel gas is admixed.

In particular, the pressure of the anode gas in the fuel cell stack is regulated as a function of the temperature of the fuel cell stack in order to maintain the required relative moisture in the membrane. Furthermore, a different electrical power output requires that the anode gas pressure in the fuel cell stack be matched to the corresponding load level. The required pressure change in the fuel cell stack is produced by increasing or reducing the volume flow of the anode gas flowing through it . The operating states of the fuel cell stack caused by the various load requirements and the parameters to be complied with in this case result in the need for a wide anode gas flow rate range. Various apparatuses are known from the prior art for controlling the flow rate of the anode gas, for example electromagnetically controlled proportional or injector valves, rotary pumps whose rotation speed is controlled or jet pumps controlled by a propellant. The last-mentioned pumps, which are also referred to as ejectors or injector pumps, are based on a principle in which the pump effect is produced by a liquid, gas or vapor jet moving at very high speed as the propellant. Compared to an anode gas recirculation arrangement, the jet pump accelerates the anode gas in a narrowing nozzle arrangement by means of the propellant jet of fuel gas, which is fed at high speed at an initial pressure. If the flow rate in the nozzle arrangement is increased adequately, this results in a pressure reduction and a suction effect which sucks the anode gas out of the recirculation line and drives it along with the fuel gas. In this case, the flow rate of the anode gas is controlled by controlling the amount of fuel gas that is supplied.

A gas supply arrangement having a jet pump arrangement such as this is disclosed, for example, in laid-open specification DE 10 2004 007 104 Al. A so-called Coanda flow amplifier is arranged in an anode gas return line and has an elongated fluid channel with a suction inlet and an outlet, through which the anode gas is fed. A fuel gas from a pressure reservoir is supplied as drive fluid into the fluid channel via a drive flow inlet at the side and a variably adjustable drive flow gap, at high speed. The fuel gas jet which is created against the channel walls of the fluid channel as a result of the Coanda effect results in a reduced pressure in the fluid channel for suction of the anode gas, and thus in a flow drive for the anode gas to be fed back to the fuel cell . Depending on the load state of the fuel cell, the anode gas volume flow is controlled by adjusting the flow cross section of the drive flow gap, and thus by means of the quantity of fuel gas supplied from the pressure reservoir. The arrangement of a Coanda flow amplifier in the cited laid-open specification is also described for a recirculation arrangement of the cathode gas and for a cathode gas supply from the surrounding air, in which compressed air is in each case made available as a drive gas from a compressed-air reservoir.

Laid-open specification DE 10 2006 019 077 Al, which actually forms the closest prior art, discloses a fuel cell system in which an anode gas is likewise fed in a circulating form in a recirculation arrangement and is in this case driven by means of a so-called ejector or ejector pump using the jet pump principle. The ejector pump is installed at a node between the circulation line and the fuel supply line and forces the fuel gas, which is supplied from a high-pressure tank by a fuel supply apparatus, at high speed from a propellant nozzle into a gas channel which is in the form of a Venturi pressure nozzle. This propellant jet of fuel gas produces a reduced pressure in the gas channel, whose effect results in the anode gas being sucked out of the circulation line which opens at the side into the gas channel. The ejector pump mixes the fuel gas with the anode gas that has been sucked up and feeds the mixture back to the fuel cell stack as the circulation line continues. The anode gas flow rate is controlled in accordance with the control signals from the control apparatus by varying the flow rate of the fuel gas flowing into the gas channel. This flow-rate change is achieved by adjusting the nozzle opening of the propellant nozzle or else by varying the fuel gas supply pressure applied to the ejector pump (primary pressure of the ejector pump) by means of a pressure regulation mechanism. The nozzle opening can be adjusted by means of an electrical actuating drive (actuator) . The pressure regulating mechanism comprises a variable valve by means of which the flow opening of the fuel supply line can be varied.

In the case of the solutions according to the prior art that are based on the jet pump principle, the feed power of the jet pump must in each case be designed for the maximum required anode gas flow rate in order to allow the appropriate volume flow of the anode gas to be produced when the power demand on the fuel cell apparatus is at its maximum. As already described above, the flow rate of the anode gas must be controlled over a wide range in order to cover all possible load levels and operating parameters. However, the jet pumps designed for the maximum power can operate only to a restricted extent in the required low-load operating states. If the fuel gas demand and thus the flow of the fuel gas demanded by the control device through the propellant nozzle is particularly low, the reduced pressure and therefore the suction effect may not be adequate for feeding the anode gas in the gas supply arrangement. This results in inadequate circulation of the anode gas in the low-load operating states, and at the same time in an inadequate control capability for the anode gas volume flow in these load ranges .

The invention is therefore based on the object of providing a gas supply arrangement for a fuel cell apparatus which ensures that the supply gas is fed in a functionally reliable manner over the entire operating range of the fuel cell apparatus. The object is achieved by a gas supply apparatus having the features of claim 1. Advantageous refinements and developments of the invention are disclosed by the dependent claims, in the following description and in the attached drawings .

According to the invention a gas supply arrangement is proposed for a fuel cell apparatus, whose jet pump arrangement has at least two jet pumps in order to feed a supply gas in a gas supply line, which jet pumps are arranged connected in parallel in order to feed the supply gas in parallel, and that can be controlled selectively by means of the control unit. In this case, two or more jet pumps are available, which are included in the gas supply line and can be connected in parallel, in which case the jet pumps can be operated in any desired combination individually, jointly or alternately. This therefore implies two or more stages of the jet pump arrangement, allowing differential provision of the supply gas volume flow matched to the respective power demanded by the fuel cell apparatus. The invention is also based on the consideration that two or more pumps connected in parallel are added to produce the volume flow. As a consequence of this, when the jet pumps are operated in parallel, each individual jet pump is of a size such that it can supply a reduced portion of the feed power, compared to the required maximum feed power. While, when the jet pump arrangement is adapted to provide a low supply gas volume flow to cover the low-load range when one jet pump is switched on individually to cover part of the feed power, a plurality of jet pumps operating in parallel and switched on jointly cover the high-load range of the operating states with a high supply volume flow. However, in particular, this means that the jet pump which is designed for partial power nevertheless produces a sufficiently high-energy propellant jet when the supply gas demanded by the control unit is particularly low, to avoid the deterioration of the suction effect when the gas volume flow is low. The supply gas volume flow can thus be maintained in a functionally reliable form and with high control accuracy even in the low-load operating states .

Even greater switching variability for the volume flow range of supply gas to be provided can be achieved by each of the jet pumps being of a size appropriate for the feed power, and the sizes differing from one another. The gas supply arrangement is preferably designed with a recirculation line between an anode-side outlet and an anode-side inlet of the fuel cell apparatus in order to feed the anode gases which emerge from the outlet from the anode side of a fuel cell, preferably of a fuel cell stack, to the inlet into the anode side. This arrangement is a result, inter alia, of the fact that the fuel contained in the anode gas only partially reacts electrochemically in the fuel cell stack, and the emerging anode gas has a residual concentration of fuel gas, so that, in order to increase the efficiency of the fuel cell arrangement, the anode gas with the residual content of fuel gas is fed back again to the fuel cell stack by means of this recirculation arrangement. In the process, the jet pump arrangement uses a propellant jet of fuel gas to produce the drive power required to circulate the anode gas with the respective volume flow rate required by a control unit. The fuel gas, preferably hydrogen, is for this purpose fed into the jet pump arrangement at a specific initial pressure from a high-pressure fuel tank. At the same time, the propellant jet is used to refresh the anode gas with unconsumed fuel. Feeding the fuel gas into the anode gas increases the fuel concentration in the anode gas compared to the anode gas on the outlet side, thus supplying it to the anode-side inlet as conditioned anode gas. The capability to connect at least two jet pumps in parallel, according to the invention, in the gas supply arrangement overcomes the restricted feedback ratio of the recirculation flow of the conventional jet pump arrangement in the low-load operating range of the fuel cell apparatus, and therefore in the lower operating range of the jet pump arrangement. When operated individually, the jet pump operated on a very low partial feed demand, with the control unit demanding a low fuel gas flow rate produces an adequate propellant jet which ensures the suction effect for a low circulation flow of the anode gas in a functionally reliable manner.

In one particularly preferred embodiment, a first jet pump is of a suitable size to feed a maximum supply gas volume flow, and a second jet pump is of a suitable size for feeding the minimum supply gas volume flow. In this case, with the two jet pumps being switched on and off alternately, the first jet pump is used as the main pump for providing an upper volume flow range of the supply gas in the high-load range of the operating states, while in contrast the second jet pump supplies the lower volume flow range for the low-load range, as a secondary pump. This embodiment of the jet pump arrangement also leads to the supply gas being fed in an operationally reliable manner over a wide volume flow range, corresponding to the operating requirements of the fuel cell apparatus .

It is preferable to use one embodiment of the jet pumps in which the jet pumps each have a propellant nozzle with an outlet opening and a respectively associated elongated pressure nozzle with an inlet opening and an outlet opening. The propellant jet flows at high speed through the outlet opening of the propellant nozzle into the inlet opening of the pressure nozzle where it produces the required reduced pressures in the elongated pressure nozzle to suck the supply gas out of the supply gas line which opens into the jet pump. Within the pressure nozzle, the propellant gas is mixed with the supply gas that is sucked in. The supply gas conditioned in this way is then fed through the outlet opening of the pressure nozzle into the supply gas line, which continues further. Jet pumps such as these operate very reliably, with a simple physical design. The operation of jet pumps such as these is further improved by the pressure nozzle having a flow cross section which tapers like a Venturi tube between an inlet flow cross section and an outlet flow cross section. The advantageous use of jet pumps of different sizes is formed, in one specific jet pump configuration, in such a manner that the outlet opening of the propellant nozzle of the first jet pump is larger than the outlet opening of the propellant nozzle of the second jet pump. In a consistent development of the various sizes with different feed powers, the inlet flow cross section of the pressure nozzle of the first jet pump is larger than the inlet flow cross section of the pressure nozzle of the second jet pump, with a fixed size ratio between the inlet flow cross sections and each of the pressure nozzles.

In one advantageous development of the jet pump arrangement, the size of the output opening of the propellant nozzle is variable. The feed range of propellant gas, in particular fuel gas, through the propellant nozzle can therefore be controlled with greater variability thus widening the variable volume flow range for the supply gas feed. By way of example, the outlet opening of the propellant nozzle may be adjusted by mechanically varying the geometry of the propellant nozzle by means of an electrical actuating drive which is driven by the control unit.

In one preferred embodiment, the jet pumps are arranged in a common housing, resulting in the jet pump arrangement forming a space-saving and compact unit. A suction chamber and pressure chamber on the housing side lead to further design simplification of the jet pump arrangement according to the invention, without any restrictions to the operational reliability. In order to allow the control unit to drive the jet pumps individually, the jet pumps each have an associated propellant gas supply line with a solenoid valve which can be driven by the control unit, in one advantageous development of the gas supply arrangement. The propellant gas is at an initial pressure, which is predetermined by the propellant gas tank, in the respective propellant gas supply line to the jet pumps. The solenoid valve which is arranged in the propellant gas supply line can control the flow rate of propellant gas by means of the control signals received from the control unit and can therefore directly influence the operation of the respective jet pump by means of the propellant jet. The respective jet pump is switched on or off by the solenoid valve as the propellant gas supply line is opened or closed while, in contrast, during steady-state operation of the solenoid valve, the propellant gas flow rate and thus the feed power of the jet pump are controlled. This control of the jet pumps ensures high functional reliability of the volume flow control of the supply gas .

In one alternative embodiment, the first and the second jet pump each have an associated propellant gas supply line, with the propellant gas supply line for the first jet pump having a solenoid valve which can be driven by the control unit . In this embodiment, only the jet pump with the maximum feed power is controlled by a solenoid valve that is driven by the control unit while, in contrast, the jet pump with the minimum feed power is operated continuously, in an uncontrolled manner. This ensures a minimum volume flow of supply gas in the gas supply line even when the main jet pump is switched off or faulty, or if the control unit is faulty.

Further features and advantages of the invention will become evident from the following description of one preferred exemplary embodiment and from the attached drawings, in which, in the individual figures:

Figure 1 shows a schematic block diagram of a gas supply arrangement for an anode-side gas supply in a fuel cell apparatus with a recirculation line and a jet pump arrangement according to the invention with two jet pumps, Figure 2 shows a side view of the jet pump arrangement with a housing, according to the exemplary embodiment,

Figure 3 shows a section illustration of the jet pump arrangement along the section A-A in figure 2.

Figure 1 shows a schematic illustration of a detail of a fuel cell apparatus 1 which has a fuel cell stack 2 with an anode side 3 and a cathode side 4, which are each separated from one another in places by a membrane which is not illustrated.

Furthermore, the fuel cell apparatus 1 has a gas supply arrangement 5 with a recirculation line 6, which connects an output 7 and an inlet 8 of the anode side 3 of the fuel cell stack 2 to one another and which includes a jet pump arrangement 9, which has two jet pumps 10, 11, in order to feed the anode gas. The jet pumps 10, 11 are arranged connected in parallel with the recirculation line 6, allowing the anode gas to be fed in parallel by means of the jet pumps

10, 11. The jet pumps 10, 11 are of different sizes, corresponding to their feed power. A first jet pump 10, referred to as the main pump, is designed for a feed power to feed the maximum anode gas volume flow. The second jet pump

11, referred to as a secondary pump, is designed for a feed power to feed the minimum anode gas volume flow. A respective propellant gas supply line 12, 13 opens into the main pump 10 and the secondary pump 11, through which fuel gas, for example hydrogen gas, is fed into the jet pumps 10, 11 at a specific initial pressure from a high-pressure fuel tank 14, and is thus admixed with the anode gas. The propellant gas supply lines 12, 13 have a respective solenoid valve 15, 16, and these solenoid valves 15, 16 are driven by a control unit 17. The gas supply arrangement 5 provides permanent circulation of the anode gas through the anode side 3 of the fuel cell stack 2, with the partially consumed anode gas emerging from the fuel cell stack 2 being passed from the outlet 7 of the anode side 3 via the jet pump arrangement 9 and being fed back, refreshed by the admixture of the hydrogen gas, to the inlet 8 of the anode side 3. The jet pumps 10, 11 produce the required feed power of the anode gas by means of the hydrogen gas which is injected into the jet pumps 10, 11 as the propellant jet and is provided in a metered form from the high-pressure fuel tank 14, via the solenoid valves 15, 16.

On the basis of the power demand on the fuel cell stack 2, which can be determined by way of example on the basis of the absolute fuel cell pressure on the anode side 3, which can be recorded by means of a pressure sensor 18, the control unit 17 determines an actuating signal for driving the solenoid valves 15, 16 and, in the wider sense, for controlling the anode gas volume flow.

Figures 2 and 3 illustrate the jet pump arrangement 9 according to the invention in a detailed form, separately from the recirculation line 6. The two jet pumps 10, 11 are jointly arranged in a compact cylindrical housing 19. The anode gas emerges from the recirculation line 6 via an inlet connecting stub 20 of the housing 19 into the jet pump arrangement 9, and is passed back into the circulation line 6 via an outlet connecting stub 21 of the housing 19. The inlet connecting stub 20 and outlet connecting stub 21 are connected to the recirculation line 6 when the gas supply arrangement 5 is in the complete state. Furthermore, figure 2 shows one of the two propellant gas supply lines 12, 13 which open at the end into the cylindrical housing 19 and are connected to the housing 19 by means of a threaded joint. At the opposite end to the propellant gas supply lines 12, 13, the cylindrical housing 19 is closed by a blind flange 22.

As can be seen from figure 3, the jet pumps 10, 11 which are integrated in the housing 19 have a respective propellant nozzle 23, 24 with an outlet opening 25, 26 and an associated elongated pressure nozzle 27, 28, with a respective inlet opening 29, 30 and a respective outlet opening 31, 32. The outlet openings 25, 26 of the propellant nozzles 23, 24 and the inlet openings 29, 30 of the pressure nozzles 27, 28 are connected to a suction chamber 33 on the housing side into which the inlet connecting stub 20 of the housing 19 also opens (although this cannot be seen in figure 3) . The outlet openings 31, 32 of the pressure nozzles 27, 28 are analogously connected to a pressure chamber 34 on the housing side, into which the outlet connecting stub 21 of the housing 19 opens (although this likewise cannot be seen in figure 3) . The two jet pumps 10, 11 are therefore connected to the recirculation line 6 in a simple, functional manner.

Each of the pressure nozzles 27, 28 is in the form of a Venturi tube composed of an inlet flow cone 35, 36, a mixing path 37, 38 and an outlet flow cone 39, 40, with the flow cross section of the pressure nozzles 27, 28 tapering between a respective inlet flow cross section 41, 42 and an outlet flow cross section 43, 44. As the hydrogen propellant jet flows into the pressure nozzles 27, 28 from the propellant nozzles 23, 24 this results in the reduced-pressure principle of the jet pumps 10, 11, in which the anode gas is sucked out of the recirculation line 6 via the suction chamber 33, and is mixed with the hydrogen gas in the mixing path 37, 38.

The different sizes of the main and secondary pumps 10, 11, which are designed for the specific feed power, result from the different sizes of the integral components of the jet pumps 10, 11. For example, the outlet opening 25 of the propellant nozzle 23 of the main pump 10 is larger than the outlet opening 26 of the propellant nozzle 24 of the secondary pump 11. The inlet flow cross section 41 of the pressure nozzle 27 of the main pump 10 is likewise larger than the inlet flow cross section 42 of the pressure nozzle 28 of the secondary pump 11. In this case, the ratio of the sizes of the pressure nozzles 27, 28 corresponding to the associated inlet flow cross section 41, 42 is also continued in its components, comprising the inlet flow cone 35, 36, mixing path 37, 38 and outlet flow cone 39, 40.

Starting from a measured value from the pressure sensor 18, which represents the corresponding demand for anode gas volume flow in the fuel cell stack 2, the control unit 17 can be used, by selection of the solenoid valves 15, 16

(OPEN/CLOSED function) to selectively drive the main pump 10 with the high feed power or the secondary pump 11 with the low feed power, and to vary the feed power of the corresponding jet pump 10, 11 within the operating characteristic of the respective jet pump 10, 11 by adjustment of the associated solenoid valve 15, 16

(continuous control function) .

In a switching mode, the main pump 10 is therefore used to provide an upper volume flow range in the high-load range of the fuel cell stack 2 while, alternatively, the secondary pump 11 covers the lower volume flow range for the low-load range of the fuel cell stack 2. The specific operating characteristics of the jet pumps 10, 11 can then be optimally controlled over the power range. A very wide volume flow range of the anode gas can also be made available, with good controllability, by the alternate use of the two jet pumps 10, 11. Because of its minimized size, the secondary pump 11 with the low feed power produces an adequate propellant jet even when the hydrogen flow rate demanded by the control unit 17 is low, thus avoiding the loss of the suction effect in the suction chamber 33. This ensures a stable circulation flow of the anode gas in the gas supply arrangement 5 even in low-load operating states of the fuel cell stack 2.

In further exemplary embodiments, which are not described or illustrated in any more detail, th

The jet pump arrangement according to the invention can likewise be provided with the advantages described above in an analogous manner in a cathode-side gas supply for the fuel cell apparatus 1, in which just one cathode gas inlet and outlet, without any circulation, is provided on the cathode side 4. In this case, the jet pump arrangement according to the invention is used to feed the cathode gas, for example external air, from the area surrounding the fuel cell arrangement 1, via a gas supply line to the cathode side 4 of the fuel cell stack 2 with compressed air being admixed from a compressed air container, and with the control unit controlling the cathode gas volume flow in the advantageous manner as described above, by driving the jet pumps, which are connected in parallel, e gas supply arrangement 5 according to the invention as described above can also be used analogously for a cathode-side gas supply for the fuel cell apparatus 1, in which a cathode gas is fed back in a recirculation line between an outlet and an inlet of the cathode side 4 of the fuel cell apparatus 1. In this case, the jet pump arrangement according to the invention is used to feed the cathode gas in the recirculation line with compressed air being admixed from a compressed-air reservoir in order to refresh and to drive the cathode gas, with the control unit controlling the circulating cathode gas volume flow in the analogously advantageous manner as described above, by driving the jet pumps, which are connected in parallel .

List of Reference Symbols

1 Fuel cell apparatus

2 Fuel cell stack

3 Anode side

4 Cathode side

5 Gas supply arrangement

6 Recirculation line

7 Outlet of the anode side

8 Inlet of the anode side

9 Jet pump arrangement

10 First jet pump, main pump

11 Second jet pump, secondary pump

12 Propellant gas supply line

13 Propellant gas supply line

14 High pressure fuel tank

15 Solenoid valve for the main pump

16 Solenoid valve for the secondary pump

17 Control unit

18 Pressure sensor

19 Cylindrical housing

20 Inlet connecting stub of the housing

21 Outlet connecting stub of the housing

22 Blind flange

23 Propellant nozzle of the main pump

24 Propellant nozzle of the secondary pump

25 Outlet opening of the propellant nozzle

26 Outlet opening of the propellant nozzle 27 Pressure nozzle of the main pump

28 Pressure nozzle of the secondary pump

29 Inlet opening of the pressure nozzle

30 Inlet opening of the pressure nozzle Outlet opening of the pressure nozzle Outlet opening of the pressure nozzle Suction chamber Pressure chamber Inlet-flow cone Inlet-flow cone Mixing path Mixing path Outlet flow cone Outlet flow cone Inlet flow cross section of the pressure nozzle Inlet flow cross section of the pressure nozzle Outlet flow cross section of the pressure nozzle Outlet flow cross section of the pressure nozzle

Claims

Patent Claims

1. A gas supply arrangement in a fuel cell apparatus, having a jet pump arrangement for feeding a supply gas in a gas supply line, using a propellant gas, and having a control unit for controlling a supply gas volume flow,

characterized in that

the jet pump arrangement (9) has at least two jet pumps (10, 11) which are arranged connected in parallel in order to feed the supply gas in parallel, and can be controlled selectively by means of the control unit (17) .

2. The gas supply arrangement as claimed in claim 1, characterized in that the gas supply line has a recirculation line (6) between an anode-side outlet (7) and an anode-side inlet (8) of the fuel cell apparatus (1) , with the supply gas that is fed being an anode gas, and the propellant gas being a fuel gas.

3. The gas supply arrangement as claimed in claim 1 or 2 , characterized in that each of the jet pumps (10, 11) is of a size appropriate for the feed power, and the sizes differ from one another.

4. The gas supply arrangement as claimed in claim 3, characterized in that a first jet pump (10) is designed for a feed power for feeding a maximum supply gas volume flow, and a second jet pump (11) is designed for a feed power for feeding a minimum supply gas volume flow.

5. The gas supply arrangement as claimed in one of the preceding claims, characterized in that the jet pumps (10, 11) have a respective propellant nozzle (23, 24) with an outlet opening (25, 26) and a respectively associated elongated pressure nozzle (27, 28) with an inlet and an outlet opening (29, 30, 31, 32) .

6. The gas supply arrangement as claimed in claim 5, characterized in that the pressure nozzle (27, 28) has a flow cross section which tapers like a Venturi tube between an inlet flow cross section (41, 42) and an outlet flow cross section (43 , 44) .

7. The gas supply arrangement as claimed in claim 5 or 6, characterized in that the outlet opening (25) of the propellant nozzle (23) of the first jet pump (10) is larger than the outlet opening (26) of the propellant nozzle (24) of the second jet pump (11) .

8. The gas supply arrangement as claimed in one of claims 5 to 7, characterized in that the inlet flow cross section (41) of the pressure nozzle (27) of the first jet pump (10) is larger than the inlet flow cross section (42) of the pressure nozzle (28) of the second jet pump (11) , and there is a fixed ratio between the sizes of the inlet flow cross section (41, 42) of each of the pressure nozzles (27, 28) .

9. The gas supply arrangement as claimed in one of claims 5 to 8, characterized in that the size of the outlet opening (25, 26) of the propellant nozzle (23, 24) is variable.

10. The gas supply arrangement as claimed in one of the preceding claims, characterized in that the jet pumps (10, 11) are arranged in a common housing (19) .

11. The gas supply arrangement as claimed in one of the preceding claims, characterized in that the outlet openings

(25, 26) of the propellant nozzles (23, 24) and the inlet openings (29, 30) of the pressure nozzles (27, 28) are connected to a suction chamber (33) on the housing size.

12. The gas supply arrangement as claimed in claim 10 or 11, characterized in that the outlet openings (31, 32) of the pressure nozzles (27, 28) are connected to a pressure chamber

(34) on the housing side.

13. The gas supply arrangement as claimed in one of the preceding claims, characterized in that the jet pumps (10, 11) each have an associated propellant gas supply line (12, 13) with a solenoid valve (15, 16) which can be driven by the control unit (17) .

14. The gas supply arrangement as claimed in one of claims 4 to 12, characterized in that the first and the second jet pump (10, 11) each have an associated propellant gas supply line (12, 13) , with the propellant gas supply line (12) for the first jet pump (10) having a solenoid valve (15) which can be driven by the control unit (17) .