WO2014173529A2

WO2014173529A2 - Device for providing air

Info

Publication number: WO2014173529A2
Application number: PCT/EP2014/001066
Authority: WO
Inventors: Viktoria FRICK; Simon Hollnaicher; Alfred Kolbe
Original assignee: Daimler Ag
Priority date: 2013-04-25
Filing date: 2014-04-22
Publication date: 2014-10-30
Also published as: WO2014173529A3; DE102013007207A1

Abstract

The invention relates to a device for providing feed air flowing to a fuel cell (6), comprising an integrated component (13) which has at least one humidifier (14), a heat exchanger (20), and at least one water separator (19, 25). The invention is characterized in that the heat exchanger (20) is cooled by a liquid coolant.

Description

Apparatus for the treatment of air

The invention relates to a device for the treatment of incoming air flowing to a fuel cell according to the closer defined in the preamble of claim 1.

A generic device for the treatment of air is known from the German patent application DE 10 2009 051 476 A1. The device for processing the supply air, which flows to the fuel cell, is designed so that it has in each case a heat exchanger as intercooler and a humidifier and a water separator. The humidifier is used as a gas / gas humidifier

trained, in which the dry supply air through the moist exhaust air from the

Fuel cell is moistened. At the same time, the exhaust air after the fuel cell and possibly after a turbine is used to cool down according to the air conveyor hot air supply, so that here an air / air heat exchanger is formed.

The device for processing the supply air to the fuel cell according to this prior art has in spite of the high integration of components in an integrated

Assembly unit has the disadvantage that in certain operating situations, for example in a sudden increase in the electrical power required by the fuel cell, no sufficient cooling of the supply air can take place, since the exhaust air flow used for cooling in relation to the supply air flow to be cooled is still very small. In reverse operation case, however, can be done too much cooling with the disadvantage of condensation of supplied moisture when the exhaust air flow used for cooling is still very large, while the supply air is already very small due to a sudden power reduction to the fuel cell.

CONFIRMATION COPY The object of the present invention is now, these mentioned

To avoid disadvantages and a device for the treatment of supply air for a

Specify fuel cell, which can be constructed very easily and efficiently.

According to the invention this object is achieved by a device having the features in the characterizing part of claim 1. Advantageous embodiments and

Further developments will become apparent from the dependent claims. in the

Claim 10 also describes a preferred use of such a device.

In the device according to the invention, it is such that the heat exchanger is cooled by a liquid cooling medium. This liquid cooling medium may in particular be the cooling medium in a cooling circuit of a fuel cell system, of which the fuel cell is a crucial part. Alternatively, the cooling medium may also belong to another cooling circuit, e.g. a high temperature or

Low-temperature cooling circuit. The heat exchanger in the apparatus for processing the supply air flowing to the fuel cell can then be flowed through accordingly via this cooling circuit which is present anyway. As a result, a targeted cooling of the supply air in all operating situations on the liquid cooling medium is possible. Even when load jumps both down and up, a sufficiently large or small heat dissipation over the liquid cooling medium can be achieved easily and efficiently.

In a very favorable embodiment of the device according to the invention, it can now also be provided that the heat exchanger is designed in the form of a plate which terminates the integrated structural unit on one side. Alternatively, the heat exchanger may also be formed as a separate module, which is integrated in the aforementioned, the integrated unit final plate. Such a plate-like heat exchanger, which consists of a plate with integrated channels for the cooling liquid, may preferably be formed as one of the end faces of the integrated assembly. As a result, a very simple and efficient construction is achieved, which allows a good and accurately controlled cooling of the supply air flow to the fuel cell via the integrated unit final plate.

In an advantageous development of this idea, it can be provided that the plate of a metallic material, in particular aluminum or a Aluminum alloy, is formed. The plate may be at this preferred

Embodiment variant may be formed in particular of a metallic material. On the one hand, this has the advantage of good heat conduction and, on the other hand, because of the high strength as the final side of the integrated structural unit, it can carry this as a self-supporting structure. Particularly preferably, aluminum or an aluminum alloy can be used. The material has the advantage of a correspondingly good heat conduction with comparatively high mechanical stability and a low weight. This will be a very efficient and yet effective

comparatively easy construction of the integrated assembly of the device for

Treatment of supply air possible.

In a further very advantageous embodiment of the device according to the invention, it can now be further provided that the plate in the integrated assembly in

complies with the intended use down. In particular, this structure, in which the plate closes the integrated assembly down, allows a structure in which the entire integrated assembly is supported on the plate. In addition, in the case arranged below in this case further components can be integrated, which must be designed to extend in the direction of gravity down or down. This may be, according to an advantageous development, for example, at least part of a water separator or one or more drainage lines for the removal of liquid from the integrated unit. Their arrangement below and in the heat exchanger designed as a plate allows a very good operation, since in particular by the liquid cooling medium, the plate at the start of the

Fuel cell system can be heated very quickly, so maybe

Frozen drainage lines and / or a frozen water is thawed very quickly. On the other hand, the plate designed as a heat exchanger keeps the temperature comparatively long even after the system has been switched off, so that water separators and drainage lines can ideally run completely empty before the structure has cooled down so far that there is a risk of water in the region of water separators and / or drainage lines frozen in the plate.

The device according to the invention as a whole allows a very compact integrated structure, which is associated with very few parts and a concomitant simplification of construction and assembly. In addition, can be realized by the integrated design of the unit weight reduction. By the Combination of heat and moisture exchange also achieves improved humidifier performance, which is sufficient in all operating situations

Humidification of the supply air flow to the fuel cell ensures and thus the

Membranes of the fuel cell typically designed as a PEM fuel cell does not dry out. The fuel cell can thus be operated very gently and efficiently over a long service life.

Another advantage which arises from the heat exchanger through which the liquid cooling medium flows is a kind of "integrated defrosting function", in that the cooling water of the gas / liquid heat exchanger used as intercooler is led past components in the integrated structural unit, which optionally thawed if water is frozen in their area

Cooling water is typically already heated immediately upon system startup, so it can be ideally used to quickly warm up the integrated package.

In an advantageous development of the device according to the invention, it can now also be provided that the plate has channels and / or functional elements for a volume flow to and / or from an anode space of the fuel cell. Also channels or functional elements such as a water separator or a gas jet pump, which correspond to the anode side of the fuel cell, in which so hydrogen and anode exhaust gas flows, can be designed integrated into the plate. This makes it possible, for example, to preheat a hydrogen stream before flowing into the anode chamber via the cooling water in the plate and thus dissipate both heat from the cooling water and heat from the supply air to the hydrogen stream. The thus preheated hydrogen flow allows better performance of the fuel cell and at the same time can be reduced by the absorption of heat by the hydrogen flow, the required cooling capacity for cooling the liquid cooling water in the fuel cell system accordingly. As a result, for example, the required outer surface of a radiator, in particular when used in a vehicle, correspondingly reduced or a possible thermal limitation of the fuel cell system due to the available

Cooling surface is prevented or at least delayed.

According to a further very favorable embodiment, it can now also be provided that the plate is simultaneously formed as part of the fuel cell. The plate can be part of the integrated assembly as well as part of the fuel cell itself in the described construction in this embodiment. This results in a very compact construction with comparatively small conduction paths, for example for air and / or gases from and / or to the fuel cell.

As mentioned, in one or more of the described embodiments, the device according to the invention can ideally be designed such that it very well supports a cold start of the fuel cell system in which it is used and, on the other hand, can be made very small, compact and efficient. It is therefore particularly suitable for fuel cell systems, which have to make do with little space, and which must be turned off and restarted comparatively often, especially at temperatures below freezing. Such fuel cell systems are mainly used in vehicles in which they are used to provide electrical drive power. The preferred use of the device according to the invention is therefore in use in such a fuel cell system, which is used in a vehicle for providing electrical drive power.

Further advantageous embodiments of the device according to the invention and its use will become apparent from the remaining dependent subclaims and will be apparent from the embodiment, which is described below with reference to the figures.

Showing:

Figure 1 is a principle indicated vehicle with a fuel cell system.

Fig. 2 is a schematic representation of a fuel cell system with a

Device according to the invention for the treatment of supply air to the

fuel cell;

3 is a schematic sectional view through a possible embodiment of the device according to the invention; and

Fig. 4 is a schematic sectional view through an alternative embodiment of the device according to the invention. In the illustration of Figure 1 is a very highly schematic a vehicle 1 indicated. The vehicle 1 comprises a fuel cell system 2, which provides electric power. This electrical power is supplied via a power electronics 3 an indicated traction motor 4 of the vehicle 1. In addition, in electrical correspondence with the power electronics 3, an electrical energy storage device 5, for example a battery, a number of high-performance capacitors or a combination thereof in the vehicle 1 may be indicated. The illustrated

Arrangement of the fuel cell system 2 in the area of the underbody of the vehicle 1 is merely exemplary. It is also possible that the fuel cell system 2 is arranged in other areas of the vehicle 1, e.g. in the area of the stem (so-called engine compartment in conventional vehicles with internal combustion engine). Likewise, the power electronics 3, the traction motor 4 and the energy storage device 5 may be arranged in other areas of the vehicle.

The fuel cell system 2 in the vehicle 1 can now be constructed, for example, as indicated in the illustration of FIG. The core of

Fuel cell system 2 forms a fuel cell 6, which is typically constructed as a stack of individual PEM cells. Each of the individual cells has an anode region, a cathode region, a proton exchange membrane and a region through which cooling fluid flows. By way of example only, in the illustration of FIG. 2, a cathode compartment 7, an anode compartment 8, a

Proton exchange membrane 9 and a heat exchanger 10 in the fuel cell 6 indicated. The cathode side or the cathode compartment 7 of the fuel cell 6 is supplied with air as an oxygen supplier via an air conveyor 11. The supply air flow flowing after the air conveying device 1 1 via an air supply line 12 first enters an integrated structural unit 13, which has a humidifier 14. After this

Humidifier 14 enters the humidified supply air via a second section 12.2 of the supply air line 12 in the cathode compartment 7 of the fuel cell 6. From the cathode compartment 7 of the fuel cell 6 exhaust air flows through a first part 15.1 an exhaust duct 15 in turn into the humidifier 14 and here passes through moisture for Water vapor permeable membranes 16 of the humidifier 14 through into the supply air. After the humidifier 14, the exhaust air flows in the embodiment shown here via a second part 15.2 of the exhaust duct 15 into a turbine 17, in which the exhaust air is expanded. In the turbine 17 can thus be at least partially recovered thermal energy and pressure energy in the exhaust air. The turbine 17, which as optional Design is to be understood sitting together with an electric machine 18 and the air conveyor 11 on a shaft, so that through the turbine 17

Air conveyor 11 is at least partially driven with. Additional required drive power is provided via the electric machine 18. This structure is also referred to as an electric turbocharger or ETC (Electric Turbo Charger). If there is greater energy recovery in the area of the turbine 17 than power required to operate the air conveyor 11, electrical power can also be generated directly via the electric machine 18 in regenerative operation and stored, for example, in the energy storage device 5 mentioned.

In order to prevent liquid droplets from reaching the region of the turbine 17, a water separator 19 is additionally provided on the cathode side of the fuel cell system 2. Also, this water separator 19 is part of the integrated assembly 13, which in addition to the water separator 19 and the humidifier 14 also includes a heat exchanger 20 described in more detail below.

The anode side of the fuel cell system 2 is designed so that the anode chamber 8 of the fuel cell 6 is supplied with hydrogen from a compressed gas reservoir 21. The hydrogen passes through a pressure regulating and metering device 22 in the region of a gas jet pump 23 as Rezirkulationsfördereinrichtung and from there into the anode compartment 8. Exhaust from the anode compartment 8 passes through a recirculation line 24 back into the range of the already-mentioned gas jet pump 23 and is in this Vacuum effects and / or momentum exchange of the fresh to the anode chamber 8 flowing hydrogen sucked in accordance with and fed to the anode chamber 8 again. This structure is also known from the general state of the art

so-called anode circuit known.

In the recirculation line 24 is another water separator 25, which is also referred to as Anodenwasserabscheider 25 to distinguish it from the cathode-side cathode water separator 19, which has been previously described. The anode water separator 25 serves to deposit droplets entrained in liquid form with the recirculated gas stream, so that they are not conveyed back into the anode chamber 8 and could clog or channel any gas-carrying channels there. The Anodenwasserabscheider 25 must be emptied, for example, depending on the level or from time to time. This is done via a valve device 26, over which, if necessary, gases can be discharged with, since in the anode circuit with time inert gases and nitrogen, which are diffused through the membranes 9 from the cathode compartment 7 in the anode compartment 8, accumulate.

The already mentioned heat exchanger 10 in the region of the fuel cell 6 and the heat exchanger 20 in the region of the integrated unit 13 are now, in addition

optionally further components to be cooled of the fuel cell system 2, part of a cooling circuit 27, which connects the heat exchangers 10, 20 with a vehicle radiator 28, via which heat in the environment of the vehicle 1 can be discharged. For this purpose, the cooling circuit 27 comprises at least one coolant delivery device 29 and in the representation of FIG. 2 a bypass line 30 with a bypass valve 31, so that the vehicle cooler 28 can be bypassed in certain situations, for example if a very rapid heating of the system takes place after starting the fuel cell system 2 should. In this case, the cooling water in the

Cooling circuit only between the heat exchangers 10, 20 and the

Coolant conveyor 29 circulates so as to quickly warm up the system and prevent cooling of the cooling water in this operating situation.

The integrated assembly 13 includes in a first embodiment, which can be seen in a schematic sectional view in Figure 3, as already from the

Representation of Figure 2 known, the humidifier 14, the cathode water separator 19 and the heat exchanger 20, which consists in particular in the form of a arranged in the lower region of the integrated assembly 13 plate 32. In this plate 32 channels 33 for the cooling water of the cooling circuit 27 are indicated. In addition, located in the region of the plate 32 at least the lower part of the Kathodenwasserabscheiders 19 and a drainage line 34 for the removal of water from the

Kathodenwasserabscheider 19 and optionally from other areas of the integrated assembly, such as from the humidifier 14. Various

Drainage lines 34 are merged within the plate 32, if several are present. You can go out from anywhere in the integrated assembly 13, but always end with their water in the environment donating part always in the area of the plate 32. The structure of the integrated unit 13 is completed by the mentioned humidifier 14. About the supply air line 12.1 flows a hot and dry air flow from the

Air conveyor 11 in the integrated unit 13 a. It leaves as with the aid of the heat exchanger 20 and the exhaust air stream cooled and moistened by the humidifier 14 supply air flow the integrated unit 13 through the supply air line 12.2 through the cathode compartment 7 of the fuel cell 6. In addition, a volume flow from the cathode compartment 7 via the exhaust duct 15.1 flows into the other Side of the humidifier 14 and moistened through the water vapor permeable membranes 16 of the humidifier 14 through the supply air. Via the cathode water separator 19, the exhaust air then flows into the exhaust air line 15.2 in the direction of the turbine 17. In the integrated unit 13, on the one hand, the passage of moisture from the exhaust air into the supply air in the area of the humidifier 14 and, at the same time, a certain heat exchange between the gases takes place. By integrated in the plate 32 cooling water channels 33 of the heat exchanger 20 is then the main cooling of the hot air supply to the air conveyor 11, so that the temperature of the supply air flow can be very selectively adjusted. Due to the high heat capacity of the cooling water, a very efficient and easily controllable or controllable cooling is possible.

The structure of the integrated assembly 13 can be realized very compact and efficient. The plate 32, which may be formed in particular from an aluminum material, has, in addition to the cooling water channels 33, as already mentioned, one or more drainage channels 34 and at least the lower part of the Kathodenwasserabscheiders 19 in the intended use. These drainage channels 34 and the lower part of the water separator 19 are particularly at risk from freezing when the fuel cell system 2 stops after switching off at temperatures below freezing until its restart. Characterized in that, as already mentioned above, in the cooling circuit 27, bypassing the

Vehicle cooler 28 a very rapid warming of the cooling water can be achieved, then the cooling water, which flows through the heat exchanger 20, then warmed up quickly, so that the plate 32 and then the entire integrated assembly 13 is heated relatively quickly. Especially the fast

Heating the plate 32 causes any frozen water in the region of the drainage line 34 and / or the lower part of the Kathodenwasserabscheiders 19 is thawed very quickly, so that the integrated assembly 13 and thus the

Fuel cell system 2 can be put into operation very quickly. In the representation of FIG. 4, an alternative embodiment of the integrated structural unit 13 is shown analogously to the illustration in FIG. The integrated assembly 13 in this case also has additional components in the area of the plate 32. These are in the illustrated embodiment, the Anodenwasserabscheider 25 and at least a portion of the recirculation line 24. In addition, there is a part of the hydrogen supply line between the pressure control and metering valve 22 and the

Gas jet pump 23 and optionally the gas jet pump 23 itself in the plate 32. This has the advantage that the hydrogen, before it flows into the gas jet pump 23, is heated by the cooling water flowing through the cooling water channels 32 cooling water. In this way, on the one hand, the cooling capacity to be applied by the vehicle radiator 28 can be reduced and, on the other hand, the hydrogen can be heated to such an extent that a condensation of moisture in the hydrogen, in particular after the

Meeting with the recirculated moist exhaust gas flow in the area of

Gas jet pump 23, safe and reliable can be avoided. As in these anode-side line elements when switching off the fuel cell system pure water in the form of water vapor and after condensing out in the form of

Liquid droplets present, these components are critical to freezing. A rapid heating of the plate 32 thus leads in the embodiment shown in Figure 4 also to a very fast start possibility for the

Anode side, so that in this structure shown in Figure 4, a very fast start of the entire fuel cell system 2 is possible. The structure is also very simple, efficient and can be realized very space-saving. It can be arranged as an integrated unit 13 alone in the fuel cell system 2 or it can be combined with other components, in particular the fuel cell 6 accordingly.

Claims

claims

1. An apparatus for treating supply air flowing to a fuel cell (6) with an integrated structural unit (13) which has at least one humidifier (14), a heat exchanger (20) and at least one water separator (19, 25), characterized that

the heat exchanger (20) is cooled by a liquid cooling medium.

2. Apparatus according to claim 1,

characterized in that

the heat exchanger (20) is in the form of a plate (32) or in the form of a separate module integrated in a plate (32), the plate (32) having cooling medium channels (33) and the integrated assembly (13) concludes a page.

3. Apparatus according to claim 2,

characterized in that

the plate (32) is made of a metallic material, in particular aluminum or an aluminum alloy.

4. Apparatus according to claim 2 or 3,

characterized in that

the plate (32) the integrated assembly (13) terminates in the intended use down.

5. Apparatus according to claim 2, 3 or 4,

characterized in that at least a part of the at least one water separator (19, 25) is integrated in the plate (32).

6. Apparatus according to claim 4 and 5,

characterized in that

the lower part of the at least one used in the intended use

Water separator (19, 25) is integrally formed in the plate (32).

7. Device according to one of claims 2 to 6,

characterized in that

at least one drainage line (34) for removing liquid in the integrated assembly (13) is formed, wherein the drainage line (34) in the plate (32) is guided to the outside.

8. Device according to one of claims 2 to 7,

characterized in that

the plate (32) channels (24) and / or functional elements (23, 25) for a

Volume flow to and / or from an anode chamber (8) of the fuel cell (6).

9. Device according to one of claims 2 to 8,

characterized in that

the plate (32) is simultaneously formed as part of the fuel cell (6).

10. Use of the device according to one of claims 1 to 9 in one

Fuel cell system (2), which is used in a vehicle (1) for providing electrical drive power.