DE102021204423A1 - Fuel cell unit with a fuel cell stack and a pump housed in a common housing with the fuel cell stack - Google Patents

Abstract

A fuel cell unit 1 is disclosed, comprising: • a fuel cell stack 4, which is formed from a plurality of fuel cells 5 arranged one on top of the other, • an anode inlet 11 for supplying fuel through a feed line 6 to an anode side 12 of the fuel cells 5 from a fuel tank 16, • a cathode inlet 21 for supplying gas containing oxygen to a cathode side 22 of the fuel cell stack 4,• an anode outlet 13 for discharging anode gas from the anode side 12,• a cathode outlet 23 for discharging cathode exhaust gas from the cathode side 22,• a pump 30 for recirculating anode gas in the feed line 6 , • the pump 30 and the fuel cell stack 4 being arranged in a common housing 40 .

Description

technical field

DE102008020362 discloses a fuel cell system including a cell stack; a temperature sensor that detects a temperature of the cell stack; an outside air temperature sensor that detects an outside air temperature; and a CPU that controls a process in the fuel cell system. When the temperature of the cell stack is lower than a predetermined temperature, the fuel cell system performs a temperature raising operation of the cell stack in which the concentration of the liquid methanol solution in an aqueous solution tank is higher than normal operation and in which an output of an aqueous solution pump is larger than in normal operation. The CPU sets a run time for the temperature raising operation based on outside air temperature, a detection result from the temperature sensor, and a run time setting table set in the memory.

description

According to the present disclosure, a fuel cell unit is to be specified which is compact in structure and thermally efficient.

Claim 1 shows a corresponding fuel cell unit. The dependent claims form advantageous developments of the fuel cell unit. The dependent claims can be combined with one another in any technologically sensible manner. The description, in particular in connection with the exemplary embodiment, additionally characterizes and characterizes the disclosure.

• • ein Brennstoffzellenstack, welcher aus mehreren aneinander angeordneten Brennstoffzellen gebildet ist,
• • einen Anodeneinlass zur Zuführung von Brennstoff durch eine Zuführleitung an eine Anodenseite der Brennstoffzellen aus einem Brennstofftank,
• • einen Kathodeneinlass zur Zuführung von Gas enthaltend Sauerstoff an eine Kathodenseite des Brennstoffzellenstacks,

• • einen Anodenauslass zur Abführung von Anodengas aus der Anodenseite,
• • einen Kathodenauslass zur Abführung von Kathodenabgas aus der Kathodenseite,
• • eine Pumpe zur Rückführung von Anodengas in die Zuführleitung,
• • wobei die Pumpe und der Brennstoffzellenstack in einem gemeinsamen Gehäuse angeordnet sind.

Accordingly, a fuel cell unit is provided, having:

• • a fuel cell stack, which is formed from several fuel cells arranged one on top of the other,
• • an anode inlet for supplying fuel through a supply line to an anode side of the fuel cells from a fuel tank,
• • a cathode inlet for supplying gas containing oxygen to a cathode side of the fuel cell stack,

• • an anode outlet for discharging anode gas from the anode side,
• • a cathode outlet for discharging cathode exhaust gas from the cathode side,
• • a pump for returning anode gas to the feed line,
• • wherein the pump and the fuel cell stack are arranged in a common housing.

The fuel cells can be PEM fuel cells. Hydrogen is provided as the fuel. Compressed air is supplied on the cathode side. Anode gas circulates on the anode side. The circulation is at least supported by the pump. It is advantageous to place the pump within the same housing as the fuel cells so that both can be cooled and heated simultaneously. The cooling and heating takes place by a cooling circuit in which a cooling medium, in particular water, is contained. During operation, the fuel cell unit and the electrochemical pump heat up so that they have to be cooled. During start-up, when the fuel cell unit in a motor vehicle sometimes has to be brought from cold temperatures below 20° C. to operating temperature, it is advantageous if heat-emitting elements are arranged spatially close to one another in the housing, so that they can be separated by thermal radiation and convection can bring each other to their respective operating temperatures more quickly.

Furthermore, a unit formed from the fuel cell stack and the pump can be constructed compactly within a common housing.

In one embodiment, it is provided that the pump is an electrochemical pump, having a large number of membranes to which an electrical potential can be applied, the membranes dividing a pump inlet and a high-pressure outlet, fuel ions being attracted to the membranes when the electrical potential is applied to the membranes High-pressure outlet are promoted and wherein the high-pressure outlet is fluidly connected to the feed line via a high-pressure return line in a return port.

The electrochemical pump is an inverted fuel cell that does not emit energy but absorbs energy in the form of electrical current, thereby ensuring ion transport through the membrane. During operation, hydrogen accumulates in the high-pressure outlet at a pressure level that is sufficiently high to be fed to the supply line. A fluid-conducting connection can be formed by a pipe connection with appropriate seals in relation to elements connected to one another. The pipe connection can have valves and branches. A fluid-conducting connection is given when fluids from from one element to the next element.

In one embodiment it is provided that the high-pressure return line is arranged inside the housing.

This in turn can create a compact fuel cell unit that is easy to install. The fuel cell unit is less sensitive to mechanical influences when sensitive components such as lines are arranged inside the housing.

In one embodiment, it is provided that the anode outlet is fluidly connected to a return line, which opens upstream from the anode inlet in a constriction of a venturi element, the venturi element being arranged in the supply line such that fuel flowing into the anode inlet returns anode gas at the constriction the return line and is mixed with the inflowing fuel.

Anode gas circulates through the return line and not the enriched gas. Anode gas discharged from the anode side is reintroduced upstream of the anode inlet. Used anode gas is discharged from the fuel cell at regular intervals when the partial pressure of the hydrogen is no longer sufficient to generate sufficient voltage in the fuel cell stack. Hydrogen flows through the venturi element from a tank into the anode inlet. A pressure relief valve is typically provided between the tank and the anode inlet since hydrogen is stored at relatively high pressure that must be reduced for fuel cell operation.

In one embodiment it is provided that at least the Venturi element is arranged inside the housing.

In one embodiment, it is provided that the Venturi element is arranged downstream of a return connection, viewed in the conveying direction of fuel into the anode side, at which the high-pressure return line is fluidly connected to the feed line.

Hydrogen, which is pumped by the electrochemical pump, is supplied to the supply line through the return connection. The electrochemical pump thus increases a volume flow of the hydrogen flowing through the venturi element, so that the suction effect in the venturi element can be ensured accordingly in order to suck in recirculated anode gas.

In one embodiment it is provided that the fluid-conducting connection of the low-pressure outlet to the cathode outlet can be opened and separated via a valve.

The valve can be opened and closed by a control unit according to an operating point of the fuel cell unit. If water has collected at the low-pressure outlet, it is expelled by opening the valve. The low pressure outlet and the pump inlet are on one side of the electrochemical membranes. The high-pressure outlet, ie the outlet at which hydrogen accumulates during operation of the electrochemical pump, is on the other side of the membrane. The electrochemical pump thus fulfills several tasks: Firstly, the suction effect on the venturi element is increased so that anode gas can be recirculated without an additional mechanical pump. Secondly, nitrogen is enriched, which can be removed through the cathode outlet. Thirdly, water is also enriched, which can be discharged intermittently.

In one embodiment it is provided that the fluid-conducting connection of the anode outlet to the cathode outlet can be opened and separated via a valve.

The anode gas can be purged at intervals when the hydrogen partial pressure has become too low or when nitrogen and water have accumulated.

In one embodiment, it is therefore provided that the valve, which can open and separate the fluid-conducting connection of the low-pressure outlet with the cathode outlet, is arranged in an operational installation position of the fuel cell unit in a motor vehicle at a lower position in the housing viewed in the direction of gravitational acceleration, so that water collects in front of the valve.

Analogous to this, it can be provided that the valve, which can open and separate the fluid-conducting connection of the anode outlet with the cathode outlet, is arranged in an operational installation position of the fuel cell unit in a motor vehicle at a lower position in the housing, viewed in the direction of gravitational acceleration, such that water collects in front of the valve.

Water, preferably in the form of water vapor and/or droplets dissolved in the gas, is required for the operation of the fuel cells since the PEM membranes have to be kept moist. Part of the water condenses and another Part forms as a result of ion transport. The valve is controlled by the controller to drain excess water when a concentration of water vapor is high enough to wet the fuel cells. Water vapor is drawn in and recirculated with anode gas in the venturi element.

In one embodiment, it is provided that apart from the fuel tank, all elements are arranged inside the housing.

This creates a fuel cell unit with a minimum number of interfaces to the vehicle environment.

character list

• 1A: schematisch eine Brennstoffzelleneinheit mit mehreren Brennstoffzellen, die in einem Gehäuse angeordnet sind, in denen auch eine elektrochemische Pumpe angeordnet ist,
• 1B: schematisch einen in 1A mit „1B“ gekennzeichneten Schnitt durch die Brennstoffzelleneinheit,
• 1C: schematisch einen in 1A mit „1C“ gekennzeichneten Schnitt durch die Brennstoffzelleneinheit,
• 1D: schematisch einen in 1A mit „1D“ gekennzeichneten Schnitt durch die Brennstoffzelleneinheit, und
• 1E: schematisch einen in 1A mit „1E“ gekennzeichneten Schnitt durch die Brennstoffzelleneinheit.

The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the present disclosure in any way. Show it:

• 1A : schematically a fuel cell unit with several fuel cells, which are arranged in a housing, in which an electrochemical pump is also arranged,
• 1B : schematic one in 1A Section marked "1B" through the fuel cell unit,
• 1C : schematic one in 1A Section marked "1C" through the fuel cell unit,
• 1D : schematic one in 1A section through the fuel cell unit marked “1D”, and
• 1E : schematic one in 1A Section marked "1E" through the fuel cell unit.

The following description is merely illustrative in nature. For purposes of clarity, the same reference numbers will be used throughout the drawings to designate similar elements. In the context of the present disclosure, terms such as "top", "bottom", "right" and "left" relate a position of elements from the exemplary embodiments to one another. The drawings are schematic. Other elements, not shown, such as valves, control elements, compressors, pumps and lines can be provided to supplement the existing elements. The use of the singular in reference to the elements is not intended to imply that only a single element need actually be provided in the corresponding position.

1A shows a fuel cell unit 1 with a fuel cell stack 4, which is formed from a plurality of fuel cells 5 arranged one on top of the other. The fuel cells 5 can be PEM fuel cells.

The fuel cell unit 1 has an anode inlet 11 for supplying fuel through a supply line 6 to an anode side 12 of the fuel cells 5 from a fuel tank 16 . The fuel can be hydrogen. Furthermore, a cathode inlet 21 for supplying compressed air to a cathode side 22 of the fuel cell stack 4 is provided. The anode inlet 11 and the cathode inlet 21 are also in FIG 1B shown on a cover plate 41. The air can be brought to a pressure level that is higher than that of the environment by a compressor (not shown).

Also shown is an anode outlet 13 for discharging anode gas from anode side 12 and a cathode outlet 23 for discharging cathode waste gas from cathode side 22. Anode gas can be recirculated via an electrochemical pump 30. The pump 30 and the fuel cell stack 4 are arranged in a common housing 40 . Anode gas and cathode gas flow crosswise through the fuel cell stack 4 to the respective outlets (see 1C ).

The electrochemical pump 30 has a large number of membranes 33 to which an electrical potential can be applied. Diaphragms 33 divide pump inlet 31 and high pressure outlet 34 . Anode gas flows through electrochemical pump 30 and is delivered across diaphragms 33 upon application of electrical potential to high pressure outlet 34 . The high-pressure outlet 34 is fluidly connected to the supply line 6 via a high-pressure return line 35 in a return connection 37, in FIG 1A if the high-pressure outlet is offset to the rear in the image plane and is thus covered by the pump inlet 31, the high-pressure outlet 34 can be seen at the top right in FIG 1E . The electrical potential at each membrane is in the range between 1V and 1.5V. Electrolysis does not take place, only hydrogen ions that are not bound to oxygen are promoted.

It can be seen that the high-pressure return line 35 is also arranged inside the housing 40 .

The anode outlet 13 is fluidly connected to a return line 36 and the pump inlet 31 , which opens into a constriction of a venturi element 17 upstream of the anode inlet 11 . The Venturi element 17 (jet pump) is arranged in the supply line 6 in such a way that fuel flowing into the anode inlet 11 is at the Constriction sucks recirculated anode gas from the recirculation line 36 and is mixed with inflowing hydrogen.

The venturi element 17 is arranged downstream of the return connection 37 in the conveying direction 7 of hydrogen into the anode side 11 . As a result, the pumped and recirculated hydrogen increases the volume flow that flows through the venturi element 17, which increases its suction effect.

The fluid-conducting connection of the low-pressure outlet 32 to the cathode outlet 23 can be opened and separated via a valve 39 . If water has accumulated here, the valve 39 is opened at regular time intervals in order to drain off water.

Furthermore, the fluid-conducting connection of the anode outlet 13 or the pump inlet 31 to the cathode outlet 23 can be opened and separated via a further valve 38 .

The valve 39, which can open and disconnect the fluid-conducting connection between the low-pressure outlet 32 and the cathode outlet 23, is arranged in a respective ready-to-operate installation position of the fuel cell unit 1 in a motor vehicle at a lower position in the housing 40 viewed in the direction of gravitational acceleration G, see above that before the valve 39 water collects.

The valve 38, which can open and separate the fluid-conducting connection of the anode outlet 13 or the pump inlet 31 with the cathode outlet 23, is in a respective ready-to-operate installation position of the fuel cell unit 1 in a motor vehicle at a lower position viewed in the direction of gravitational acceleration G Housing 40 arranged so that water accumulates in front of the valve 39 . The unit made up of fuel cell stack 4 and pump 30 is surrounded by cover plates 41 , 42 . A separating plate 43 is arranged between the fuel cell stack 4 and the electrochemical pump 30 . The spatial orientation in relation to the gravitational acceleration G can also be different than in 1A until 1E shown.

Although at least one exemplary embodiment has been presented in the foregoing description as well as the description of the figures, it should be recognized that a large number of variations exist. Furthermore, it should be appreciated that the embodiment(s) are only examples and are not intended to limit the scope, applicability, or precise configuration in any way. Rather, the description and description of the figures provide useful guidance for those skilled in the art for implementing at least one embodiment, it being understood that various changes in form and function of the described features may be made without departing from the scope of the claims and their equivalents .

reference list

1

fuel cell unit

4

fuel cell stack

5

fuel cells

6

supply line

7

conveying direction

11

anode inlet

12

anode side

16

fuel tank

17

venturi element

21

cathode inlet

22

cathode side

23

cathode outlet

30

pump

31

pump inlet

32

low pressure outlet

33

membranes

34

high pressure outlet

35

high pressure return line

36

return line

37

feedback port

38

Valve

39

Valve

40

Housing

41

cover plate

42

cover plate

43

partition plate

G

acceleration due to gravity

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102008020362 [0001]

Claims (11)

Fuel cell unit (1), comprising: • a fuel cell stack (4), which is formed from several fuel cells (5) arranged one on top of the other, • an anode inlet (11) for feeding fuel through a feed line (6) to an anode side (12) of the fuel cells (5) from a fuel tank (16), • a cathode inlet (21) for supplying gas containing oxygen to a cathode side (22) of the fuel cell stack (4), • an anode outlet (13) for discharging anode gas from the anode side (12), • a cathode outlet (23) for discharging cathode waste gas from the cathode side (22), • a pump (30) for returning anode gas to the feed line (6), • wherein the pump (30) and the fuel cell stack (4) are arranged in a common housing (40). Fuel cell unit (1) after claim 1 , wherein the pump is an electrochemical pump (30) having a plurality of membranes (33) to which an electrical potential can be applied, the membranes (33) dividing a pump inlet (31) and a high-pressure outlet (34), wherein at When the electrical potential is applied to the membranes (33), fuel ions are conveyed to the high-pressure outlet (34) and the high-pressure outlet (34) is fluidly connected to the feed line (6) via a high-pressure return line (35). Fuel cell unit (1) after claim 2 wherein the high pressure return line (35) is located within the housing (40). Fuel cell unit (1) according to one of Claims 1 until 3 wherein the anode outlet (13) is fluidly connected to a return line (36) which, upstream of the anode inlet (11), opens into a constriction of a venturi element (17), the venturi element (17) thus being arranged in the feed line (6). that in the anode inlet (11) inflowing fuel at the constriction sucks recirculated anode gas from the return line (36) and is mixed with inflowing fuel. Fuel cell unit (1) after claim 4 wherein at least the venturi element (17) is arranged within the housing (40). Fuel cell unit (1) after claim 4 and/or 5, wherein the venturi element (17) is arranged downstream of a return connection (37), viewed in the conveying direction (7) of fuel into the anode side (12), at which the high-pressure return line (35) is connected to the supply line (6 ) connected is. Fuel cell unit (1) according to one or more of Claims 4 until 6 , wherein the fluid-conducting connection of the low-pressure outlet (32) to the cathode outlet (23) can be opened and separated via a valve (38). Fuel cell unit (1) according to one or more of Claims 4 until 7 , wherein the fluid-conducting connection of the anode outlet (13) to the cathode outlet (23) can be opened and separated via a valve (39). Fuel cell unit (1) according to one or more of Claims 4 until 7 , wherein the valve (39), which can open and separate the fluid-conducting connection of the low-pressure outlet (32) with the cathode outlet (23), viewed in an operational installation position of the fuel cell unit (1) in a motor vehicle at a direction of gravitational acceleration (G). bottom position in the housing (40) is arranged so that water collects in front of the valve (39). Fuel cell unit (1) according to one of Claims 8 and/or 9, wherein the valve (38), which can open and separate the fluid-conducting connection of the anode outlet (13) with the cathode outlet (23), in an operational installation position of the fuel cell unit (1) in a motor vehicle at a point in the direction of gravitational acceleration (G) is located in the lower position in the housing (40) as viewed so that water collects in front of the valve (39). Fuel cell unit (1) according to one or more of claims 2 until 9 , wherein apart from the fuel tank (16) all elements are arranged within the housing (40).

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