Recirculating fan

Abstract

A recirculation fan (17) for a device for recovering gases containing hydrogen gas in a fuel cell system, comprising: a fan (23) drivable by a turbine, the fan being designed to deliver a return flow; and a turbine (31), which is designed to drive the fan (23) and which can be driven by the hydrogen flow.

Description

Technical Field

[0001] The present invention relates to a recirculation blower for gas recovery for hydrogen-containing gas in a fuel cell system. Background Art

[0002] A fuel cell system may be provided in a vehicle (eg, a car, a train, an airplane or a ship), in which electrical energy is generated, for example, from hydrogen in order to drive the vehicle.

[0003] In addition to the fuel cell unit supplied with gaseous hydrogen, the fuel cell system can also have a recovery device for recovering unconsumed hydrogen gas to the input end of the fuel cell unit. A recirculation fan is provided in the recovery device to recover unconsumed hydrogen gas to the input end. This allows for lower fuel consumption. Recirculation in particular increases fuel utilization and thus efficiency.

[0004] Conventional recirculation fans are electrically or mechanically driven. Common solutions based on the ejector principle do not require an external energy supply. The recirculation fan can be designed as an electrically driven compressor, such as a radial compressor. Side channel compressors and rotary piston fans (so-called Roots blowers) with relatively small rated pressure ratios can also be used. Summary of the invention

[0005] The proposed object is to provide an alternative recirculation fan.

[0006] This object is achieved by a recirculation fan for a gas recovery device for hydrogen-containing gas in a fuel cell system having the features of claim 1 .

[0007] The recirculation blower includes: a blower that can be driven by a turbine, the blower being designed to convey the return flow; and a turbine that is designed to drive the blower, and the turbine can be driven by the hydrogen flow.

[0008] The recirculation system in the fuel cell system proposes that the recirculation blower is connected to the hydrogen storage.

[0009] The recirculation blower is used to recover gas containing hydrogen gas. The term "gas" includes both hydrogen gas and gas mixture containing hydrogen gas. Advantageously, hydrogen gas is the main component of such gas mixture. The recirculation blower improves the efficiency and service life of a fuel cell system for a fuel cell type electric vehicle (such as a car, train, airplane or ship). The proposed solution aims to reduce the power required for the recirculation blower to a minimum in order to save fuel (i.e. hydrogen) and thus increase the range of the vehicle.

[0010] The basis of the recirculation blower is a blower driven by a turbine, similar to the compressor of a turbocharger, where the turbine itself is flowed through and driven by the hydrogen. The recirculation blower uses the expanding hydrogen from the hydrogen storage and the pressure potential of the hydrogen storage to drive the turbine, which then drives the blower.

[0011] The recirculation blower concept based on a hydrogen turbine requires little electricity, since at most the idling ventilation of the fuel cell unit requires electricity, and significantly saves electrical energy that could be used to increase the vehicle's range. In addition, the turbine drive offers additional cost-saving potential, since no expensive power electronics, coolants, air bearings or measures to prevent hydrogen permeation are required.

[0012] The recirculation fan delivers the hydrogen that is not consumed when reacting in the fuel cell unit back to the fuel cell unit of the fuel cell system, which reduces the hydrogen consumption and aging of the fuel cell unit. The recirculation fan is also advantageously used as a compressor to maintain the flow direction of hydrogen toward the input end of the fuel cell. The blower as a compressor delivers the hydrogen that is not consumed back to the input end of the fuel cell unit as a reflux. The drive of the blower is carried out by the following hydrogen flow, which is guided into the fuel cell unit from the hydrogen storage tank, through the turbine of the recirculation fan as the fuel of the fuel cell unit. Therefore, the recirculation system of the fuel cell system utilizes the higher pressure level in the hydrogen storage tank to improve the efficiency of the system.

[0013] In one embodiment, the recirculation blower includes a blower impeller in the blower for conveying the return flow and a turbine impeller in the turbine. The blower impeller and the turbine impeller are coupled to each other so that the rotation of the turbine impeller drives the blower impeller by transmitting the rotation of the turbine impeller to the blower impeller. The turbine impeller can be driven by the hydrogen flow.

[0014] The fan impeller is driven by a turbine, wherein hydrogen from the hydrogen storage drives the turbine impeller and is then introduced into the fuel cell unit. The hydrogen flowing into the fuel cell unit is used to drive the recirculation fan on its way there.

[0015] The return flow with the hydrogen to be recovered and the hydrogen flow with the hydrogen to be supplied from the hydrogen storage to the fuel cell unit flow through the recirculation blower in a spatially separated manner.

[0016] In one embodiment, the recirculation blower includes a turbine inlet in the turbine through which hydrogen from the hydrogen storage can be directed as a hydrogen stream to the turbine impeller, so that the hydrogen stream drives the turbine impeller and causes it to rotate. The hydrogen stream leaves the turbine through the turbine outlet and flows into the fuel cell unit. The return flow flows from the blower inlet, through the blower to the blower outlet.

[0017] The fan can be driven by the turbine alone. In such an embodiment, no additional electric drive is provided to the fan, thus avoiding the problem of hydrogen permeation into electrical or electromagnetic components. In the case of such a turbine-driven fan, the cost and complexity are lower.

[0018] In one embodiment, the fan can additionally be driven electrically, so that as an alternative to the turbine drive, the fan can be driven electrically, or the turbine drive can be electrically assisted. In the case of a combination of turbine drive and electric drive, the power requirement for the electric drive is significantly lower than in the case of a conventional purely electric drive. During operation of the fuel cell system, the turbine drive saves considerable electrical energy. The electric motor provided for the electric drive must be sealed to prevent the intrusion of hydrogen.

[0019] Advantageously, the power of the turbine drive is adjustable so that the compressor power of the blower is also set accordingly. Such regulation can be achieved by throttling the hydrogen flow from the reservoir that drives the turbine impeller. This can be achieved, for example, by a valve connected upstream of the turbine, which throttles the hydrogen flow as a pressure reducing valve. Alternatively or additionally, this regulation can be carried out in such a way that the hydrogen flow from the reservoir only partially flows through the turbine, while the rest is directed to bypass the turbine. For this purpose, a valve, in particular a bypass valve, can be provided. In one embodiment, the bypass valve can be arranged near the wastegate of the supercharger. The valve can be an integral component of the recirculation blower, or can be set as a separate component in the recirculation system in order to regulate the turbine. In the case where the turbine drive is electrically assisted, the regulation of the turbine drive can also be carried out by regulating the electric drive by means of energization. In order to regulate the turbine drive and in order to utilize the expansion pressure difference of the reservoir Another approach proposes to extract part of the electrical energy by slowing down the turbine.

[0020] In one embodiment, the fan impeller and the turbine impeller are comprised by a rotor. The rotor comprises the rotating part of the recirculation fan. Advantageously, the rotor can be driven electrically, so that the fan impeller does not necessarily have to be driven by the turbine impeller. In one embodiment, the rotation of the rotor driven by the turbine can be electrically assisted. In one embodiment, an electric motor is coupled to the rotor so that the electric motor drives the rotor or assists the rotation of the rotor. The electric motor can be manipulated so that the power of the fan can be influenced thereby.

[0021] In one embodiment, the rotor comprises a shaft, which is connected to a turbine wheel and a fan wheel. The turbine wheel and the fan wheel are arranged at the end region of the shaft. The electric motor is arranged between the fan wheel and the turbine wheel. The shaft can be driven by the electric motor or its rotation can be assisted by the electric motor. This arrangement of the electric motor is accompanied by a compact construction.

[0022] Alternatively, the motor is arranged on the side of the fan impeller facing away from the turbine impeller, or the motor is arranged on the side of the turbine impeller facing away from the fan impeller. In these arrangements, the fan impeller and the turbine impeller can be positioned close to each other. This can be achieved to the extent that, in one embodiment, the turbine impeller and the fan impeller are arranged in a back-to-back arrangement and are designed as one component.

[0023] In one embodiment, the hydrogen flow can be at least partially directed to bypass the turbine impeller, thereby affecting the power of the blower. This type of regulation of the turbine can be performed by a bypass valve (also called a "wastegate") or a similar power regulation mechanism. When the bypass valve is open, the bypass valve causes the hydrogen flow to be at least partially directed to bypass the turbine impeller. In the closed state, the hydrogen flow flows through the turbine impeller.

[0024] The electric motor and the bypass valve make it possible to control the power of the fan and adapt it to the operating requirements.

[0025] A recirculation fan is used in the recirculation system of the fuel cell system. The recirculation fan is connected to the hydrogen storage tank, from which a hydrogen flow is fed to drive the turbine impeller. The turbine inlet of the recirculation fan is connected to the hydrogen storage tank in such a way that the hydrogen flow drives the turbine impeller.

[0026] Advantageously, the recirculation fan is connected between the hydrogen storage and the fuel cell unit so that the hydrogen flow can drive the recirculation fan and then flow into the fuel cell unit. This connection can be carried out by means of further components, for example by means of a valve. In addition, the return flow with unconsumed hydrogen flows back (is conveyed back by the fan) to the fuel cell unit. For this purpose, the fan of the recirculation fan is connected between the output and the input of the fuel cell unit.

[0027] The recirculation blower described above may be based on a conventional blower design which has been adapted for its use with a gas flow of hydrogen, so that the cost and complexity are also evident in terms of power electronics and electric motors. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Several embodiments are described in detail below in conjunction with the accompanying drawings. In the accompanying drawings:

[0029] Figure 1 Schematically illustrating an embodiment of a conventional fuel cell system,

[0030] Figure 2 An embodiment of a fuel cell system with a recirculation fan driven by a turbine is schematically shown,

[0031] Figure 3 A further embodiment of a fuel cell system having a turbine-driven recirculation fan with electric assistance is schematically shown.

[0032] Figure 4 An embodiment of a rotor and a motor is schematically shown.

[0033] Figure 5 Another embodiment of a rotor and a motor is schematically shown.

[0034] Figure 6 Another embodiment of a rotor and a motor is schematically shown.

[0035] Figure 7 Schematically shows Figure 5 An embodiment, wherein there is a journal, and

[0036] Figure 8 One embodiment of a fan impeller and a turbine impeller in a back-to-back arrangement is schematically shown. DETAILED DESCRIPTION

[0037] In the figures, identical or functionally identical components are provided with the same reference symbols.

[0038] Figure 1An embodiment of a conventional fuel cell system with a fuel cell unit 1 is schematically shown, and the fuel cell unit includes a stack with multiple fuel cells. The fuel cells each have an anode and a cathode and a diaphragm arranged therebetween. Fuel is supplied on the anode side, which is gaseous hydrogen in this embodiment. It is supplied from a hydrogen storage 3 designed as a tank, via a pressure reducer 5 and a pressure regulating valve 7 connected downstream of the pressure reducer 5. Hydrogen from the pressure regulating valve 7 and hydrogen recovered from the fuel cell unit 1 are supplied on the anode side via an injector 9 of the fuel cell unit 1. Oxidant, such as air, is supplied on the cathode side. It is supplied via a filter 11 and an air compressor 13. The compressed air passes through an air humidifier 15 to improve efficiency and is supplied to the fuel cell unit 1 on the cathode side.

[0039] The fuel and oxidant react inside the fuel cell and release energy while producing water. However, the hydrogen flowing from the hydrogen storage 3 to the anode side is usually not completely converted into water. Nitrogen and water (formed when reacting in the anode and may make the efficiency worse and worse) are discharged from the fuel cell unit 1 to provide space for hydrogen. Thus, efficient reaction can be achieved and the sensitive membrane in the fuel cell is not damaged, so that the fuel cell system 1 works well even in cold conditions and has a long service life. For the above viewpoints, a recovery loop is provided at the anode, and the recovery loop has a discharge valve 19 and a recirculation fan 17 in a recovery device for the gas containing hydrogen gas. The recirculation fan 17 improves the efficiency and robustness of the system (especially in terms of protection and service life in cold conditions). Nevertheless, it is optional to set the recovery loop. A separate recovery loop with a recirculation fan 17 is provided at the anode, which returns the hydrogen that has not been consumed and blows nitrogen and excess water out of the battery cell. The recovery loop feeds the unconsumed hydrogen back to the anode input on the one hand and discharges nitrogen and excess water on the other hand via a discharge valve 19. The water is conducted to an air humidifier 15 in order to humidify the input air.

[0040] The cooling connection 21 of the fuel cell unit 1 is connected to a cooling system in order to cool the fuel cell unit 1 .

[0041] Figure 2 An embodiment of a fuel cell system with a recirculation fan with a turbine drive is schematically shown. The following description focuses on the differences from the previous embodiments.

[0042] In this embodiment, the air supply is also carried out via the filter 11 , the air compressor 13 and the air humidifier 15 , which is connected to the output end of the fuel cell unit 1 .

[0043] The recirculation fan 17 is connected to the recovery branch so as to recover the hydrogen generated at the output end side of the fuel cell unit 1 to the input end of the fuel cell. In this embodiment, the recirculation fan 17 is not only connected between the output end and the input end of the fuel cell unit 1, but also additionally connected between the hydrogen storage 3 and the fuel cell unit 1.

[0044] The hydrogen storage 3 provides fuel, i.e. hydrogen, for the fuel cell unit 1. A pressure reducing valve 51 is provided between the hydrogen storage 3 and the recirculation blower 3. A pressure control valve 53 is provided between the recirculation blower 17 and the fuel cell unit 1. The valves 51 and 53 regulate the pressure of the hydrogen flow flowing into the recirculation blower 17 and flowing out of it.

[0045] The recirculation fan 17 comprises a fan 23 having a fan inlet 25, a fan outlet 27 and a fan impeller 29, which conveys the return flow containing unconsumed hydrogen through the fan 23. The output end of the fuel cell unit 1 is connected to the fan inlet 25. The input end of the fuel cell unit 1 is connected to the fan outlet 27. The recirculation fan 17 comprises a turbine 31 having a turbine inlet 33, a turbine outlet 35 and a turbine impeller 37, which is driven by the hydrogen flow fed from the hydrogen storage 3. The turbine inlet 33 is connected to the pressure reducing valve 51. The turbine outlet 35 is connected to the pressure control valve 53. The turbine impeller 37 and the fan impeller 29 are connected to each other by the shaft 41, so that the rotation of the turbine impeller 37 is transmitted to the fan impeller 29 and drives the fan impeller. The rotating part of the recirculation fan 17 is called a rotor. The rotor comprises a turbine wheel 37, a fan wheel 29 and a shaft 41. The fan 23 can be driven by a turbine 31 which itself is driven by the hydrogen flow. The fan 23 and the turbine 31 are arranged in a housing of the recirculation fan 17.

[0046] The turbine 31 is designed such that the hydrogen flow can be temporarily at least partially directed around the turbine impeller 37. For this purpose, a bypass valve 39 is provided, which in the open state directs the hydrogen flow from the turbine inlet 33 to the turbine outlet 35 at least partially around the turbine impeller 37. In this way, the effective power of the recirculation fan 17 can be controlled, because the amount of hydrogen directed to the turbine impeller 37 is regulated by the bypass valve 39. This influences the rotation speed of the turbine impeller 37 and thus the effective power of the fan 23. The pressure reducing valve 51 and the bypass valve 39 make it possible to adjust the hydrogen flow through the turbine 31 and thus also to adjust the turbine power by means of the hydrogen flow, which has an influence on the compressor power of the fan 23.

[0047] During operation, the hydrogen flow from the hydrogen storage 3 through the turbine 3 to the fuel cell unit 1 drives the turbine impeller 37. The rotation is transmitted to the fan impeller 29 through the shaft 41, and the fan impeller compresses the unconsumed hydrogen from the fuel cell unit 1 through the fan 23 and delivers it to the input end of the fuel cell unit 1.

[0048] Figure 3 An embodiment of a fuel cell system having a turbine-driven recirculation fan 17 with electric assistance is schematically shown. To avoid repetitions, the description focuses on the recirculation fan 17 and its differences from the above-described embodiments.

[0049] In this embodiment, the drive of the fan 23 can alternatively be carried out in an electric manner or be electrically assisted. For this purpose, an electric motor 43 is provided, which drives the rotor with the turbine impeller 37 and the fan impeller 29. The power required by the electric motor 43 (which is generally arranged to assist the turbine drive) is significantly less than the electric drive power of a conventional electrically driven recirculation fan. This is accompanied by a compact structure and lower complexity and cost.

[0050] The electric motor 43 can be controlled so that the power of the fan 23 can be influenced. Thus, in addition to the bypass valve 39, there is also the possibility of influencing and controlling the effective power of the fan 23 by adjusting the rotational speed of the shaft 41 and thus the fan impeller 29 by means of the electric motor 43.

[0051] Figure 4 The diagram of the rotor and the motor 43 in one embodiment is schematically shown. The turbine impeller 27 and the fan impeller 29 are connected by the shaft 41 in such a way that the rotation of the turbine impeller 37 is transmitted to the fan impeller 29. The motor 43 is arranged between the fan impeller 29 and the turbine impeller 37, and the motor 43 is connected to the shaft 41 so that the shaft can be driven by the motor 43 or its rotation can be assisted by the motor 43. An embodiment of the motor 43 includes a magnetic active area 45 on the shaft 41, such as a permanent magnet. Around the magnetic active area 45, there are arranged magnetic active areas 47 of the stator, which are designed, for example, as coils with windings through which a time-varying current can flow. According to the time-varying current flowing through the winding, a time-varying magnetic field is induced, which together with the permanent magnets of the magnetic active area 43 of the rotor causes the rotor to rotate. The control circuit controls the motor 43.

[0052] Figure 5Another embodiment of the rotor and the motor is schematically shown. In this embodiment, the motor 43 is mounted on the fan side, so the motor is not arranged between the turbine impeller 37 and the fan impeller 29, but adjacent to the side of the fan impeller 29 facing away from the turbine impeller 37. With this arrangement, the fan impeller 29 and the turbine impeller 37 can be arranged closer than in the previous embodiment.

[0053] Figure 6 Another embodiment of the rotor and the motor is schematically shown. In this embodiment, the motor 43 is mounted on the turbine side, so the motor is arranged adjacent to the side of the turbine impeller 37 facing away from the fan impeller 29. With this arrangement, the fan impeller 29 and the turbine impeller 37 can be arranged closely adjacent to each other.

[0054] Figure 7 Schematically shows Figure 5 The embodiment of the rotor and the motor of the present invention and the arrangement possibilities of the bearings of the shaft 41 are shown. By arranging the motor 43 on the fan side, various possibilities for arranging the journals of the shaft 41 are obtained. The journal 61 can be arranged between the fan impeller 29 and the turbine impeller 37. Alternatively, the journal 62 can be arranged between the fan impeller-turbine impeller assembly and the motor 43, that is, between the fan impeller 29 and the motor 43. It is also conceivable to provide two journals 61, 62.

[0055] Of course, when the electric motor 43 is arranged on the turbine side (such as Figure 6 ), there is also the above-mentioned arrangement possibility of the journals 61, 62 of the shaft 41. The journal 61 can be arranged between the fan impeller 29 and the turbine impeller 37 or between the fan impeller-turbine impeller assembly and the motor 43, that is, between the turbine impeller 37 and the motor 43.

[0056] Figure 8 It is schematically shown that the fan impeller-turbine impeller assembly is designed as a fan impeller 29 and a turbine impeller 37 arranged back to back, and they are arranged directly adjacent to each other on the back side. The connecting function of the shaft 41 is omitted between the impellers 29 and 37, because the fan impeller 29 and the turbine impeller 37 are designed as one component in this embodiment. Alternatively, in the back-to-back arrangement, the backs of the separately formed turbine impeller 37 and the fan impeller 29 can also be in contact.

[0057] The features given above and in the claims and which can be derived from the drawings can be implemented advantageously both individually and in various combinations. The invention is not limited to the described embodiments but can be varied in various ways within the capabilities of a person skilled in the art.

[0058] List of Reference Numerals

[0059] 1 Fuel cell

[0060] 3 Hydrogen storage

[0061] 5 Pressure reducer

[0062] 7 Pressure regulating valve

[0063] 9 Injector

[0064] 11 Filters

[0065] 13. Air compressor

[0066] 15. Air humidifier

[0067] 17 Recirculation fan

[0068] 19 Drain valve

[0069] 21 Cooling connector

[0070] 23 Fan

[0071] 25 Fan inlet

[0072] 27 Fan outlet

[0073] 29 Fan impeller

[0074] 31 Turbine

[0075] 33 Turbine inlet

[0076] 35 Turbine outlet

[0077] 37 Turbine impeller

[0078] 39 Bypass valve

[0079] 41 Axis

[0080] 43 Electric Motor

[0081] 45 Magnetic action area

[0082] 47 Magnetic action area

[0083] 51 Pressure reducing valve

[0084] 53 Pressure control valve

[0085] 61, 62 journal

Claims

1. A recirculation fan (17), the recirculation fan being used for recovering gas containing hydrogen in a fuel cell system, the recirculation fan comprising: a fan (23) which can be driven by the turbine and is designed to convey the return flow; as well as A turbine (31) is designed to drive the fan (23) and can be driven by a hydrogen flow.

2. The recirculation fan (17) according to claim 1, The recirculation fan comprises a fan impeller (29) for conveying the return flow, and a turbine impeller (37), wherein the fan impeller and the turbine impeller are coupled to each other in such a way that the rotation of the turbine impeller (37) drives the fan impeller (29), wherein: The turbine wheel (37) can be driven by the hydrogen flow.

3. The recirculation fan (17) according to claim 2, The recirculation blower comprises a turbine inlet (33) in the turbine (31), through which hydrogen, in particular hydrogen from a hydrogen storage (3), can be guided as a hydrogen flow to the turbine impeller (37), so that the hydrogen flow drives the turbine impeller (37) and causes it to rotate.

4. Recirculation fan (17) according to one of the preceding claims, in, The fan (23) can be driven electrically and / or the turbine drive of the fan can be electrically assisted.

5. Recirculation fan (17) according to one of the preceding claims, in, The power of the turbine drive can be adjusted.

6. A recirculation fan (17) according to claim 4 or 5, in, The fan impeller (29) and the turbine impeller (37) are comprised by a rotor, and an electric motor (43) is coupled to the rotor such that the electric motor drives the rotor and / or assists in the rotation of the rotor.

7. The recirculation fan (17) according to claim 6, Among them, The rotor comprises a shaft (41) which is connected to the turbine impeller (37) and the fan impeller (29), and the shaft (41) can be driven by an electric motor (43), or the rotation of the shaft can be assisted by the electric motor (43).

8. The recirculation fan (17) according to claim 7, in, The electric motor (43) is arranged between the fan impeller (29) and the turbine impeller (37), or the electric motor (43) is arranged on a side of the fan impeller (29) facing away from the turbine impeller (37), or the electric motor (43) is arranged on a side of the turbine impeller (37) facing away from the fan impeller (29).

9. The recirculation fan (17) according to claim 8, in, The turbine impeller (37) and the fan impeller (29) are arranged in a back-to-back arrangement and are designed as one component.

10. Recirculation fan (17) according to any one of claims 2 to 9, in, In particular, the hydrogen gas flow can be at least partially directed past the turbine wheel (37) via a bypass valve (39).

11. Recirculation fan (17) according to one of the preceding claims, in, In particular, the hydrogen flow can be throttled on the input side of the turbine (31) by means of a pressure reducing valve (51).

12. A recirculation system in a fuel cell system, comprising a recirculation blower (17) according to one of the preceding claims, which is connected to a hydrogen storage device (3).

13. The recirculation system according to claim 12, in, The turbine inlet (33) of the recirculation blower (17) is connected to the hydrogen storage tank (3), so that the hydrogen gas stream can be fed from the hydrogen storage tank (3).

14. The recirculation system according to claim 12 or 13, in, The recirculation fan (17), in particular the turbine (31) of the recirculation fan, is connected between the hydrogen storage tank (3) and the fuel cell unit (1).

15. The recirculation system according to claim 14, in, The recirculation fan (17), in particular a fan (29) of the recirculation fan, is connected between an output and an input of the fuel cell unit (1).

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