WO2015177708A1

WO2015177708A1 - Conditioning device for an oxidant, fuel cell system and vehicle with a fuel cell system

Info

Publication number: WO2015177708A1
Application number: PCT/IB2015/053650
Authority: WO
Inventors: Viktoria FRICK; Simon Hollnaicher; Alfred Kolbe; Peter Ziegler
Original assignee: Nissan Motor Co., Ltd
Priority date: 2014-05-20
Filing date: 2015-05-18
Publication date: 2015-11-26
Also published as: DE102014007469A1

Abstract

The invention relates to a conditioning device (12) for an oxidant, which can be introduced into a fuel cell stack of a fuel cell system (10). The conditioning device (12) includes a cooler (16) for cooling the oxidant and a humidifier (18) for humidifying the oxidant. The cooler (16) and the humidifier (18) are integrated in a common constructional unit, wherein an insulating element (42) for thermally insulating the humidifier (18) from the cooler (16) is disposed in the constructional unit between the cooler (16) and the humidifier (18). Furthermore, the invention relates to a fuel cell system (10) with such a conditioning device (12) and a vehicle with a fuel cell system (10).

Description

Conditioning device for an oxidant, fuel cell system and vehicle with a fuel cell system

The invention relates to a conditioning device for an oxidant, which can be introduced into a fuel cell stack of a fuel cell system. The conditioning device includes a cooler for cooling the oxidant and a humidifier for humidifying the oxidant. Herein, the cooler and the humidifier are integrated in a common constructional unit. Furthermore, the invention relates to a fuel cell system with such a conditioning device as well as to a vehicle with a fuel cell system.

DE 10 2012 003 922 A1 describes a fuel cell system with a fuel cell stack, to which compressed supply air is supplied as an oxidant. Herein, the supply air compressed by means of an electrically driven turbocharger first flows through a charge air cooler and then a humidifier, which are integrated in a common constructional unit. In addition, this constructional unit and the fuel cell stack of the fuel cell system can be disposed in a common housing, wherein a temperature equalization between the components located in the housing is to be ensured by a thermal insulation of the housing.

In such an arrangement, the full functionality of the humidifier cannot be ensured in unrestricted manner.

Furthermore, US 2009/0098425 A1 describes a fuel cell system, in which the hydrogen supplied to a fuel cell is humidified in a humidifier. Herein, the exhaust gas of an anode of the fuel cell stack is supplied to the humidifier as a humectant, thus the consumed hydrogen. This hydrogen is cooled before entry into the humidifier in a condenser to transfer the water vapor contained in the exhaust gas into condensed water. A mixture of the exhaust gas with condensed water is then introduced into the humidifier. The humidifier has a heating device, and it is disposed in a common constructional unit together with the condenser. An insulating plate is provided in the constructional unit between the condenser and the humidifier.

It is the object of the present invention to provide a conditioning device of the initially mentioned kind improved with regard to the functionality of the humidifier, as well as a fuel cell system with such a conditioning device and a vehicle with this fuel cell system.

This object is solved by a conditioning device having the features of claim 1 , a fuel cell system having the features of claim 1 1 and a vehicle having the features of claim 12. Advantageous configurations with convenient developments of the invention are specified in the dependent claims.

In the conditioning device according to the invention, an insulating element is disposed in the constructional unit between the cooler and the humidifier, which serves for thermally insulating the humidifier from the cooler. This is based on the realization that the temperature of the media in the humidifier, of the components of the humidifier itself as well as of components adjoining to the humidifier should not exceed a defined value. Such a value can in particular be determined in a technical specification relating to the humidifier. By providing the insulating element between the humidifier and the cooler, heat transfer from the cooler to the humidifier is particularly largely inhibited. This allows maintaining the temperature in the humidifier for example below the value mentioned in the technical specification and minimizing exceeding this value, respectively. Thus, overheating of the humidifier as well as the media located in the humidifier can be avoided.

Namely, usually, the oxidant to be supplied to the fuel cell stack, which can in particular be air, is compressed by means of a compressor, wherein it heats. The insulating element now prevents heat from being transferred to the humidifier and the media located therein from the heated oxidant entering the cooler. Thus, a temperature intended for the operation of the humidifier, in particular an optimum temperature, can be maintained in the humidifier over the run time thereof. In particular, it can be ensured that the temperature of the humidifier preset by a technical specification is not exceeded.

If the cooler is a charge air cooler passed by a cooling medium, thus, in particular at the beginning of the operation of the charge air cooler or at particularly cold ambient temperatures, a comparatively cold cooling medium can flow into the cooler. In such a case, the insulating element prevents undercooling the humidifier and the media located therein as well as in particular falling below a specified minimum temperature of the humidifier.

By providing the insulating element, thus, the functionality of the humidifier can be permanently ensured. If it is a humidifier of a fuel cell system for a vehicle, thus, in this manner, the functionality of the fuel cell system and of the vehicle can also be ensured. By avoiding the occurrence of critical temperatures of the humidifier, in addition, extension of the lifetime of this component of the conditioning device can be achieved. A partial area of a housing for instance of the cooler or the humidifier can be constituted by the insulating element. Herein, the partial area has a higher thermal insulating effect than at least one further partial area of the housing. This can occur by providing a locally increased wall thickness of the housing and/or by providing the housing with a thermally insulating coating in the partial area. In such a manner, the insulating element can be particularly simply integrated in the conditioning device. If the insulating element formed by increasing the wall thickness provides a bottom plate of the housing of the humidifier, thus, the insulating element additionally stiffens the housing of the humidifier.

Preferably, the insulating element is formed as a plate. Such an inherently stiff plate not only serves for heat insulation of the humidifier with respect to the cooler, but it also provides a supporting function in the conditioning device. This results in increased stiffness and stability of the conditioning device and in particular of the humidifier of the conditioning device. If a stiffness and/or stability of the humidifier or of the conditioning device to be satisfied is indicated in a technical specification, thus, by the formation of the insulating element as a plate, this defined specification can be achieved. Namely, the plate-shaped insulating element results in additional stability of the conditioning device.

The plate can abut on a housing of the humidifier on the one hand and on a housing of the cooler on the other hand and thus increase the stiffness of the humidifier and also stabilize the cooler.

It is particularly advantageous if the insulating element formed as a plate abuts on a bottom plate of the housing of the humidifier. Namely, an additional supporting function for the humidifier is then achieved by the plate and in particular deflection of the humidifier is prevented. A leakage or other damage of the humidifier due to deflection of the same can thus be inhibited. By supporting the humidifier from below, in particular technical specifications of the humidifier with regard to the stiffness, leakages and a fracture strain can be satisfied. This too, results in improved durability and endurance of the conditioning device.

Furthermore, the formation of the insulating element as a plate can be technically particularly simply realized, which is associated with a low manufacturing effort of the insulating element. In particular, due to the plate-shaped formation of the insulating element, expensive formation of other components of the conditioning device including additional stiffening structures as for instance of the housing of the humidifier and/or the housing of the cooler and/or a supporting structure of the conditioning device can be omitted, and the desired stiffness of the conditioning device can yet be obtained. Thus, the material cost for the conditioning device can also be reduced. In addition, the insulating element formed as a plate can be produced reliable in terms of process and in simple manner.

In a further advantageous configuration, the insulating element has a first passage for the oxidant to be humidified arriving from the cooler and a second passage for the humidified oxidant arriving from the humidifier. Thus, the insulating element can be particularly well integrated in the conditioning device and the stiffening and insulating function thereof can be well utilized. In particular, thus, a particularly large thermal insulation of the humidifier with respect to the cooler is ensured.

This in particular applies if the insulating element has a first humectant passage for a humectant arriving from the fuel cell stack and a second humectant passage for the humectant exiting the humidifier according to a further advantageous configuration.

It has proven further advantageous if the first passage and the second passage for the oxidant are disposed in edge areas of the insulating element opposing each other and the first and the second humectant passage are disposed in further edge areas of the insulating element opposing each other. Thereby, a cross-flow of the humectant and the oxidant in the humidifier can be particularly simply realized. Such a cross-flow is conducive to a particularly good transfer of humidity to the oxidant.

The second humectant passage can be disposed upstream of a water separator of the conditioning device. This is in particular reasonable if the exhaust gas of a cathode of the fuel cell stack is used as the humectant, which contains the product water formed in the fuel cell reaction. By providing the water separator, namely, cathode exhaust gas particularly largely freed of liquid water then exits the conditioning device. Thus, this exhaust gas can be used in a turbine of an exhaust gas turbocharger of the fuel cell system for compressing the oxidant by means of a compressor wheel of the exhaust gas turbocharger.

If in a further, preferably alternative configuration, the second humectant passage is disposed downstream of a water separator integrated in the humidifier of the conditioning device, thus, a particularly compact construction of the conditioning device can be achieved. The conditioning device can include a supporting structure, by which at least a partial area of a bottom plate of the water separator is formed. In this manner, for instance a bottom bowl of the water separator can in particular be provided in low-effort manner. Herein, the supporting structure preferably has a receiving space for a line bundle of the cooler being able to be passed by cooling liquid. Thereby, a particularly compact conditioning device is provided.

Particularly simply and beneficial for the purposes of thermal insulation as well as the supporting function, the insulating element can be formed of a plastic. Herein, in particular a temperature-resistant thermoplastic plastic such as polyphenylene sulfide (PPS) can be employed as the material.

The fuel cell system according to the invention, which can in particular be employed in a vehicle, includes a conditioning device according to the invention and a fuel cell stack. An oxidant cooled and humidified in the conditioning device can be introduced into the fuel cell stack. Such a fuel cell system can include a plurality of further components in particular usual for fuel cell systems of vehicles, which therefore presently do not have to be explained in detail.

The vehicle according to the invention includes a fuel cell system according to the invention.

The advantages and preferred embodiments described for the conditioning device according to the invention also apply to the fuel cell system according to the invention and the vehicle according to the invention.

The features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the description of figures and/or shown in the figures alone are usable not only in the respectively specified combination, but also in other combinations or alone, without departing from the scope of the invention. Thus, implementations are also to be considered as encompassed and disclosed by the invention, which are not explicitly shown in the figures or explained, but arise from and can be generated by separated feature combinations from the explained implementations.

Further advantages, features and details of the invention are apparent from the claims, the following description of preferred embodiments as well as based on the drawings. Therein show: Fig. 1 severely schematized a section of a fuel cell system of a vehicle, in which an air conditioning unit, a humidifier and a cooler are integrated, wherein an insulating plate is disposed between the humidifier and the cooler;

Fig. 2 a variant of the fuel cell system according to Fig. 1 , in which a water

separator is integrated in the humidifier;

Fig. 3 the insulating plate in a perspective view;

Fig. 4 the insulating plate in a plan view;

Fig. 5 the insulating plate in a rear view; and

Fig. 6 the insulating plate in a side view;

Of a fuel cell system 10 of a vehicle, in Fig. 1 , a conditioning device for an oxidant, namely an air conditioning unit 12, is severely schematized shown. In the air conditioning unit 12, the air to be supplied to a fuel cell stack 14 (compare Fig. 2) of the fuel cell system 10 is cooled and humidified. Hereto, the air conditioning unit 12 includes a cooler, which presently is formed as a charge air cooler 16, and a humidifier 18. The charge air cooler 16 is accommodated in the area of a supporting structure 50 of the air conditioning unit 12. Hereto, a receiving space for a line bundle 46 of the charge air cooler 16 being able to be passed by cooling liquid is provided in the supporting structure 50 (cf. Fig. 2).

Arriving from a (not shown) compressor wheel of an exhaust gas turbocharger, compressed and herein heated supply air flows through an inlet 20 into the charge air cooler 16 of the air conditioning unit 12. The exhaust gas turbocharger can in particular be a turbocharger with additionally an electrically drivable compressor wheel. In order to cool the compressed supply air, the charge air cooler 16 is supplied with a cooling liquid, which enters the charge air cooler 16 via an input 22 and again exits the charge air cooler 16 via an output 24.

The supply air 20 cooled by means of the cooling liquid then flows to a dry side 26 of the humidifier 18, which is separated from a wet side 30 of the humidifier 18 by means of a membrane 28. From the wet side 30, water passes the membrane 28 and thus humidifies the supply air still dry upon entry into the humidifier 18. This humidity transfer is illustrated by an arrow 32 in Fig. 1.

The humidified supply air exits the air conditioning unit 12 via an outlet 34 and then is supplied to the fuel cell stack 14 (cf. Fig. 2). The transport of the supply air to be humidified to the dry side 26 of the humidifier 18 and from the dry side 26 towards the outlet 34 is schematically illustrated by further arrows 36 in Fig. 1.

As the humectant for the supply air, presently, the exhaust air of the fuel cell stack 14 is employed, thus the exhaust gas of a cathode of the fuel cell stack 14, which contains the product water formed in the fuel cell reaction. This cathode exhaust gas is introduced into the air conditioning unit 12 via a further inlet 38, which is disposed in the area of the supporting structure 50 for the charge air cooler 16 of the air conditioning unit 12 just as the inlet 20 for the compressed supply air to be humidified and the outlet 34 for the humidified supply air.

The cathode exhaust gas containing product water then flows to the wet side 30 of the humidifier 18 and is passed through a water separator (not shown in Fig. 1) after exiting the humidifier 18 to separate remaining liquid water from the cathode exhaust gas. The cathode exhaust gas freed of liquid water then flows towards a turbine of the exhaust gas turbocharger via a further outlet 40.

Presently, an insulating element formed as a plate, namely an insulating plate 42, prevents the humidifier 18 as well as the media located therein from being exposed to a too high thermal load. Namely, the insulating plate 42 particularly largely prevents heat transfer from the charge air cooler 16, into which the supply air heated by compression flows via the inlet 20, to the humidifier 18. The insulating plate 42 furthermore prevents heat loss of the humidifier 18 for instance in a case, in which the charge air cooler 16 is supplied with particularly cold cooling liquid.

Besides the function of thermal insulation, the insulating plate 42 has a function stiffening the air conditioning unit 12 and in particular the humidifier 18. Namely, the humidifier 18, which in particular can be formed as a plate humidifier, in which the membranes 28 are flatly formed, is supported by the insulating plate 42 disposed at a bottom of the humidifier 18. Herein, the membrane plates of the humidifier 18 can be stacked in a vertical direction of the humidifier 18 or perpendicularly to the vertical direction, which is illustrated by the arrow 32 in Fig. 1. In both cases, the insulating plate 42 disposed at the bottom of the stack of the membrane plates prevents deflection of the humidifier 18. In this manner, leakages and other damages of the humidifier 18 can be effectively avoided.

However, the insulating plate 42 can also reduce a heat transfer from the charge air cooler 16 to the humidifier 18 in an air conditioning unit 12, in which the humidifier 18 has membranes 28 formed as hollow fibers, wherein the hollow fiber membranes can in particular be present in a bundle. Herein, the air to be humidified preferably flows through the hollow fiber membranes, and the cathode exhaust gas flows around the hollow fiber membranes.

The charge air cooler 16 is integrated in the preferably plate-shaped supporting structure 50, which imparts increased stiffness to the water separator and has a receiving space for coolant lines of the charge air cooler 16. In addition, in the region of the supporting structure 50, preferably, at least one drainage line is provided, via which water separated by means of the water separator as well as liquid water originating from the humidifier 18 can be discharged. Such a supporting structure 50 can in particular be manufactured from an aluminum alloy, and it is also stabilized by the insulating plate 42. The insulating plate 42 is preferably formed of a plastic as for instance polyphenylene sulfide.

The variant of the fuel cell system 10 shown in Fig. 2 differs from the variant shown in Fig. 1 substantially in that a water separator 44 is provided immediately on the output side of the humidifier 18. Furthermore, a line bundle 46 of the charge air cooler 16 is

schematically shown, through which the cooling liquid flows. Moreover, a drainage line 48 is schematically shown in Fig. 2, which is formed in the supporting structure 50 for the charge air cooler 16 of the air conditioning unit 12.

However, in the variant of the fuel cell system 10 shown in Fig. 2 too, the inlet 20 for the compressed, not yet cooled supply air, the outlet 34 for the humidified supply air, the inlet 38 for the cathode exhaust gas arriving from the fuel cell stack 14 and the outlet 40 for the cathode exhaust gas exiting the water separator 44, thus freed of liquid water, are formed in the region of the supporting structure 50. Moreover, a bottom bowl of the water separator 44 is formed by the supporting structure 50.

Fig. 3 shows the insulating plate 42 in a perspective view. The insulating plate 42 has first edge areas 52, 54 opposing each other and substantially parallel to each other. In the lower edge area 52 in Fig. 3 a passage 56 is formed, through which the wet cathode exhaust gas, thus the humectant for the supply air, passes in the operation of the air conditioning unit 12 and arrives at the wet side 30 of the humidifier 18. Via a passage 58 disposed in the edge area 54 opposing the lower edge area 52, the cathode exhaust gas arriving from the wet side 30 of the humidifier 18 again passes the insulating plate 42 after humidifying the supply air. From the passage 58, the cathode exhaust gas flows to the water separator in the fuel cell system according to Fig. 1. The two passages 56, 58 are each formed in the manner of an elongated slit rounded in respective end regions in the insulating plate 42.

In analogous manner, in two further edge areas 60, 62 parallel to each other and opposing each other, passages 64, 66 for the supply air are formed in the insulating plate 42. The supply air to be humidified passes the left passage 66 in Fig. 3 and thus arrives at the dry side 26 of the humidifier 18. Subsequently, the humidified supply air then again passes the insulating plate 42, namely through the passage 64 also formed in the manner of an elongated slot rounded in the end regions. This passage 64 is present in the edge area 60 disposed opposing the passage 66. The passages 64, 66 for the supply air are formed substantially perpendicularly to the passages 56, 58 for the cathode exhaust gas.

By the arrangement of the passages 56, 58, 64, 66 in the insulating plate 42 described with reference to Fig. 3, a cross-flow of the supply air to be humidified and the cathode exhaust gas serving as the humectant can be realized in the humidifier 18.

Fig. 4 shows the insulating plate 42 in a plan view on a top side of the insulating plate 42 also shown in Fig. 3. In comparison, Fig. 5 shows a view on a bottom side of the insulating plate 42. In Fig. 6, finally, a side view of the insulating plate 42 is shown.

List of reference characters

10 Fuel cell system

12 Air conditioning unit

14 Fuel cell stack

16 Charge air cooler

18 Humidifier

20 Inlet

22 Input

24 Output

26 Dry side

28 Membrane

30 Wet side

32 Arrow

34 Outlet

36 Arrow

38 Inlet

40 Outlet

42 Insulating plate

44 Water separator

46 Line bundle

48 Drainage line

50 Supporting structure

52 Edge area

54 Edge area

56 Passage

58 Passage

60 Edge area

62 Edge area

64 Passage

66 Passage

Claims

1. Conditioning device for an oxidant, which can be introduced into a fuel cell stack (14) of a fuel cell system (10), including a cooler (16) for cooling the oxidant and including a humidifier (18) for humidifying the oxidant, wherein the cooler (16) and the humidifier (18) are integrated in a common constructional unit,

characterized in that

an insulating element (42) for thermally insulating the humidifier (18) from the cooler (16) is disposed in the constructional unit between the cooler (16) and the humidifier (18).

2. Conditioning device according to claim 1 ,

characterized in that

at least a partial area of a housing, in particular of a housing of the humidifier (18), is constituted by the insulating element (42), wherein the partial area has a higher thermal insulating effect than at least one further partial area of the housing.

3. Conditioning device according to claim 1 or 2,

characterized in that

the insulating element (42) is formed as a plate, which abuts on a housing of the humidifier (18), in particular on a bottom plate of the housing of the humidifier (18), on the one hand and on a housing of the cooler (16) on the other hand.

4. Conditioning device according to any one of claims 1 to 3,

characterized in that

the insulating element (42) has a first passage (66) for the oxidant to be humidified and arriving from the cooler and a second passage (64) for the humidified oxidant arriving from the humidifier.

5. Conditioning device according to any one of claims 1 to 4,

characterized in that

the insulating element (42) has a first humectant passage (56) for a humectant arriving from the fuel cell stack (14) and a second humectant passage (58) for the humectant exiting the humidifier (18).

6. Conditioning device according to claim 4 and 5,

characterized in that

the first passage (66) and the second passage (64) for the oxidant are disposed in edge areas (60, 62) opposing each other, and the first and the second humectant passage (56, 58) are disposed in further edge areas (52, 54) of the insulating element (42) opposing each other.

7. Conditioning device according to claim 5 or 6,

characterized in that

the second humectant passage (58) is disposed upstream of a water separator of the conditioning device (12).

8. Conditioning device according to any one of claims 5 to 7,

characterized in that

the second humectant passage (58) is disposed downstream of a water separator (44) integrated in the humidifier (18) of the conditioning device (12).

9. Conditioning device according to claim 7 or 8,

characterized in that

the conditioning device (12) includes a supporting structure (50) in particular having a receiving space for a line bundle (46) of the cooler (16) capable of being passed by cooling liquid, by which at least a partial area of a bottom plate of the water separator (44) is formed.

10. Conditioning device according to any one of claims 1 to 9,

characterized in that

the insulating element (42) is formed of a plastic.

1 1. Fuel cell system, in particular for a vehicle, including a conditioning device (12) according to any one of claims 1 to 10 and including a fuel cell stack (14), into which an oxidant cooled and humidified in the conditioning device (12) can be introduced. Vehicle with a fuel cell system (10) according to claim 11