HUMIDIFIER, FUEL CELL DEVICE WITH A HUMIDIFIER AND MOTOR VEHICLE WITH A FUEL CELL DEVICE COMPRISING A HUMIDIFIER

Abstract

A humidifier comprises at least one humidifier module, which has a membrane permeable to water vapor and respectively on both sides of the membrane, a flow field frame with at least two walls defining a flow channel. A thermal bridge with an increased thermal conductivity compared to the membrane protrudes through the membrane. A fuel cell device comprises such a humidifier and a motor vehicle includes a fuel cell device comprising such a humidifier.

Claims

1. A humidifier, comprising: at least one humidifier module that comprises: a membrane permeable to water vapor; a first flow field frame with at least two walls defining a first flow channel on a first side of the membrane; a second flow field frame with at least two walls defining a second flow channel on a second side of the membrane opposite the first side; and a thermal bridge with a higher thermal conductivity than the membrane which protrudes through the membrane, wherein the thermal bridge is sealed off from the membrane; wherein the thermal bridge includes a pin that protrudes through the membrane from the first side of the membrane to a pin seat in the second flow field frame, and wherein the pin is formed as one piece with the walls and/or the pin seat is arranged in the walls.

2. The humidifier according to claim 1, wherein the humidifier includes a plurality of humidifier modules collectively having a plurality of membranes separated by flow field frames, and wherein each flow field frame has a plurality of flow channels with associated walls.

3. (canceled)

4. The humidifier according to claim 1, wherein a plurality of the pins and a corresponding number of pin seats are provided, which are associated with the walls.

5. The humidifier according to claim 2, wherein each of a partial quantity of the flow field frames have pins on both sides of the flow field frame assignable to the adjacent membranes, and each of a set of the flow field frames complementary to the partial quantity have pin seats on both sides of the flow field frame.

6. (canceled)

7. The humidifier according to claim 1, wherein the flow field frames are formed from a material with higher conductivity than the membrane.

8. (canceled)

9. A fuel cell device with a humidifier comprising: at least one humidifier module that comprises: a membrane permeable to water vapor; a first flow field frame with at least two walls defining a first flow channel on a first side of the membrane; a second flow field frame with at least two walls defining a second flow channel on a second side of the membrane opposite the first side; and a thermal bridge with a higher thermal conductivity than the membrane that protrudes through the membrane, wherein the thermal bridge is sealed off from the membrane; wherein the thermal bridge includes a pin that protrudes through the membrane from the first side of the membrane to a pin seat in the second flow field frame, and wherein the pin is formed as one piece with the walls and/or the pin seat is arranged in the walls.

10. A motor vehicle with a fuel cell device which has a humidifier comprising: at least one humidifier module that comprises: a membrane permeable to water vapor; a first flow field frame with at least two walls defining a first flow channel on a first side of the membrane; a second flow field frame with at least two walls defining a second flow channel on a second side of the membrane opposite the first side; and a thermal bridge with a higher thermal conductivity than the membrane that protrudes through the membrane, wherein the thermal bridge is sealed off from the membrane; wherein the thermal bridge includes a pin that protrudes through the membrane from the first side of the membrane to a pin seat in the second flow field frame, and wherein the pin is formed as one piece with the walls and/or the pin seat is arranged in the walls.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0012] FIG. 1 shows a highly schematic representation of a fuel cell device comprising a humidifier.

[0013] FIG. 2 shows a longitudinal section through a section of a humidifier.

[0014] FIG. 3 shows a cross-section through a section of a humidifier.

[0015] FIG. 4 shows a representation corresponding to FIG. 2 of an embodiment of a humidifier.

[0016] FIG. 5 shows a representation corresponding to FIG. 3 of an embodiment of a humidifier.

[0017] FIG. 6 shows a representation corresponding to FIG. 4 of a further embodiment of a humidifier.

[0018] FIG. 7 shows a representation corresponding to FIG. 6 as shown in FIG. 5.

[0019] FIG. 8 shows a top view of a flow field frame with flow fields rotated 90 degrees and the thermal bridges arranged at the intercepts.

DETAILED DESCRIPTION

[0020] FIG. 1 shows a part of a fuel cell device 1, wherein the fuel cell device 1 comprises a device for regulation of humidity of a plurality of fuel cells combined in a fuel cell stack 2.

[0021] Each of the fuel cells comprises an anode, a cathode, and a proton-conductive membrane separating the anode from the cathode. The membrane is formed from an ionomer, such as a sulfonated tetrafluoroethylene polymer (PTFE) or a perfluorinated sulfonic acid (PFSA) polymer. Alternatively, the membrane may be formed as a hydrocarbon membrane.

[0022] A catalyst may additionally be admixed to the anodes and/or the cathodes, wherein the membrane may be coated on its first side and/or on its second side with a catalyst layer made of a noble metal or a mixture comprising noble metals such as platinum, palladium, ruthenium or the like, which serve as reaction accelerators in the reaction of the respective fuel cell.

[0023] Fuel (e.g., hydrogen) can be supplied to the anode via an anode compartment. In a polymer electrolyte membrane fuel cell (PEM fuel cell), fuel or fuel molecules are split into protons and electrons at the anode. The PEM allows the protons to pass through, but is impermeable to the electrons. For example, the reaction: 2H.sub.2.fwdarw.4H.sup.++4e.sup.− (oxidation/electron release) occurs at the anode. Whereas the protons pass through the PEM to the cathode, the electrons are conducted to the cathode or to an energy storage device via an external circuit.

[0024] The cathode gas (e.g., oxygen or oxygen-containing air) can be supplied to the cathode via a cathode compartment, so that the following reaction takes place on the cathode side: O.sub.2+4H.sup.++4e.sup.−.fwdarw.2H.sub.2O (reduction/electron capture).

[0025] To ensure ionic conductivity for hydrogen protons through the PEM, the presence of water molecules in the PEM is required. For this reason, the cathode gas is, in particular, humidified before it is supplied to the fuel cell to bring about moisture saturation of the PEM.

[0026] Since several fuel cells are combined in the fuel cell stack 2, a sufficiently large amount of cathode gas must be provided, such that a large cathode gas mass flow is provided by a compressor 3, wherein as a result of the compression of the cathode gas, its temperature increases greatly. The conditioning of the cathode gas, i.e., its adjustment with respect to the parameters desired in the fuel cell stack 2, takes place in a humidifier 4.

[0027] FIG. 2 and FIG. 3 show a humidifier known from the state of the art. Three membranes 5 are shown in FIG. 2, the alternating flow field frames 6 of which are assigned to a flow channel 7 for moist exhaust air and for the dry supply air, the flow and flow direction of which are symbolized by the arrows. FIG. 3 shows a view from the side of the construction of FIG. 2, where, in particular, the plurality of flow channels 7 formed in the flow field frames 6 can be seen. The membrane 5 located between the flow channels 7 in the flow field frames 6 makes it possible to humidify the dry supply air due to its water vapor-permeable property, wherein due to the low thermal conductivity of the membrane 5, the desired temperature control cannot be achieved.

[0028] FIG. 4 shows a representation of an embodiment, comparable to FIG. 2, of a humidifier 4, formed as described herein, in which a heat transfer indicated by the filled-out arrows is made possible by a thermal bridge 8. For this purpose, the thermal bridge 8 protrudes through the membrane 5. The thermal conductivity of the thermal bridge 8 is increased compared to that of the membrane 5. Since, in this embodiment example, there is a plurality of humidifier modules with a plurality of membranes 5 separated by the flow field frames 6, there is also a plurality of flow channels 7 with associated walls 9 and a plurality of pins 10 and pin seats 11 forming the thermal bridge 8. The pins 10 and the pin seats 11 are associated with the walls 9, which themselves consist of a material with good thermal conductivity, for example a metal. The dimensions of the pins 10 are adapted to the dimensions of the pin seats 11 for good heat transfer; in particular, the pins 10 are arranged to fit precisely in the pin seats 11 and/or are pressed into them. FIG. 4 shows an embodiment in which the flow field frames 6 for the supply air and for the exhaust air are of identical design, i.e., have the pins 10 on one side and the pin seats 11 on the other side, whereas FIG. 6 shows an alternative embodiment in which a partial quantity of the flow field frames 6 has the pins 10 on both sides assignable to the adjacent membrane 5 and the complementary set of the flow field frames 6 has the pin seats 11 on both sides.

[0029] It should moreover be noted that the thermal bridges 8 are sealed off from the membrane 5, this being achieved by sealing off the pins. This can be achieved, for example, by O-rings 12 or glued joints or an interference fit that becomes effective when the humidifier modules are tensioned.

[0030] Aspects and features of the various embodiments described above can be combined to provide further embodiments. These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled.