Humidifier, in particular for a fuel cell

Abstract

A humidifier has a stack unit having a plurality of water-vapor-permeable membranes which are arranged parallel one above the other and spaced apart from one another. The membranes are enclosed at the edges at least in sections by an enclosing part, wherein the enclosing parts of membranes lying one above the other are directly connected to one another in a flow-tight manner.

Claims

1. A humidified capable of humidifying air for a fuel cell, comprising: at least one stack unit including a plurality of membranes permeable to water vapor in which each membrane is arranged one above the other and spaced apart from one another; a plurality of enclosing parts, each enclosing part secured onto a membrane edge of a respective one of the plurality of membranes, each enclosing part having: a flat contacting region arranged laterally outwardly from the membrane edge; a profile section connected to the contacting region and arranged perpendicularly between the membrane edge and the contacting region; a first foil connected to the profile section, the first foil resting directly on and extending on and fixedly connected to a first side of the respective one of the plurality of membranes; and a second foil connected to the profile section and resting directly on and extending on and fixedly connected to an opposite second side of the respective one of the plurality of membranes, such that the membrane edge is sandwiched between the first and second foil; wherein the membrane edge is enclosed at least in sections, by the foils of the enclosing part; and wherein the membrane edge of a first membrane of the plurality of membranes is fixedly connected to a first enclosing part of the plurality of enclosing parts; wherein the membrane edge of an immediately adjacent second membrane of the plurality of membranes is fixedly connected to a second enclosing part of the plurality of enclosing parts; wherein a connecting region of the first connecting part is fixedly directly connected onto the connecting region of the second connecting part, forming a flow-tight connection; wherein the connecting regions of the first connecting part and the second connecting part are arranged between membrane planes of the first membrane and the second membrane.

2. The humidifier according to claim 1, further comprising a support grid fixedly connected to and arranged between the membrane and the foil, at least on one side of the membrane.

3. The humidifier according to claim 2, wherein the support grid covers at least 30 percent of a membrane surface area of the membrane.

4. The humidifier according to claim 1, wherein the profile section is formed to be angular.

5. The humidifier according to claim 1, wherein a first angular section of the profile section extends in a direction traverse to the membrane plane; wherein a second angular section of the profile section extends in a direction parallel to the membrane plane and offset from the membrane plane.

6. The humidifier according to claim 1, wherein the enclosing part encloses the membrane circumferentially.

7. The humidifier according to claim 1, wherein the enclosing parts of adjacent membranes are connected to one another at two opposing side edges.

8. The humidifier according to claim 7, wherein at flow channels offset in a parallel manner, the enclosing parts are connected to sealing strips at the front ends which are offset by 90 degrees.

9. The humidifier according to claim 1, wherein the enclosing parts of adjacent membranes are securely connected to one; wherein the secure connection is a welded connection.

10. The humidifier according to claim 1, further comprising spacers arranged between two adjacent membranes of the plurality of membranes.

11. The humidifier according to claim 10, wherein adjacent membranes of the plurality of membranes are separated by a space therebetween; wherein the spacers are only provided and arranged between every second space between adjacent membranes.

12. The humidifier according to claim 10, wherein the spacers form a spacer grid.

13. The humidifier according to claim 11, wherein space between adjacent membranes form flow channels; wherein the spacers are formed in a flow-guiding manner and guide the flow in the flow channels in which the spacers are arranged, from an inflow side to an outflow side in the flow channel.

14. A fuel cell comprising a humidifier according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further advantages and expedient embodiments can be found in the further claims, the description of the figures and the drawings. In the figures:

(2) FIG. 1 shows a humidifier for a fuel cell having a cartridge inserted into a housing, the cartridge containing a plurality of water-vapor-permeable membranes which are arranged parallel one above the other and form a stack unit,

(3) FIG. 2 shows a cross-section of a stack unit having membranes that are enclosed in the lateral region or edge region by enclosing parts which are connected to one another,

(4) FIG. 2A shows an enlarged view of the dashed cloud region 2A in FIG. 2,

(5) In the figures, the same components are designated by the same reference signs.

DESCRIPTION OF PREFERRED EMBODIMENTS

(6) In FIG. 1, a humidifier 1 for a fuel cell is illustrated, via which fresh air enriched with moisture and having a minimum moisture level is fed to the fuel cell. In a housing 2, the humidifier 1 has a cartridge 3 which is inserted into the housing in a replaceable or fixed manner, and which serves for transmitting the moisture contained in an exhaust gas flow to a dry fresh air flow, which is fed to the fuel cell. The cartridge 3 has a stack unit comprising a plurality of water-vapor-permeable membranes stacked one above the other.

(7) The housing 2 of the humidifier 1 is provided with a fresh air channel 4 via which ambient air is supplied as fresh air. The fresh air channel 4 comprises a feeding section 4a upstream of the cartridge 3 and a discharging section 4b downstream of the cartridge.

(8) The housing 2 is provided with an exhaust gas channel 5 which is offset at an angle of 90? relative to the fresh air channel 4 and via which exhaust gases of the fuel cell, which are enriched with moisture, are guided through the cartridge. The exhaust gas channel 5 has a feeding section 5a upstream of the cartridge 3 and a discharging section 5b downstream of the cartridge.

(9) The fresh air flow 6 and the exhaust gas flow 7 intersect according to the orientation of the channels 4 and 5 at an angle of 90?; however, the air flows 6 and 7 within the cartridge 3 are separated by the water-vapor-permeable membranes, which only permit water exchange from the exhaust gas flow 7 laden with a high level of moisture to the dry fresh air flow 6.

(10) FIG. 2 shows a cartridge 3 in a cross-sectional view. The cartridge 3 comprises a stack unit having a plurality of parallel membranes 8 which are arranged one above the other and spaced apart from one another, each of which are water-vapor-permeable, but do not permit air to pass through. The flow chambers or channels for guiding the fresh air flow and the exhaust gas flow therethrough extend in each case between two membranes 8. The fresh air channels 4 and the exhaust gas channels 5 alternate between the membranes 8 in the direction as they are arranged one above the other.

(11) Each membrane 8 is enclosed in its edge region by an enclosing part 9 comprising two foils 10 and 11, which are connected to one another by laminating or welding. One foil 10 lies on one side of the edge region of the membrane 8 and the second foil 11 lies on the opposite side of the membrane 8. The edge regions of the membranes 8 are fixedly connected to the enclosing part 9 formed by the foils 10 and 11 by means of the laminating or welding process. Optionally, only one foil laid around the edge region of the membrane 8, instead of two foils 10 and 11, is used for the enclosing part 9.

(12) Laterally outside of the membrane 8, the enclosing parts 9 form a profile section 12 which is formed to be angular or beveled or optionally cranked or curved and has a contact region 13 that extends parallel and offset to the plane of the membrane 8. The contact regions 13 of adjacent enclosing parts 9 contact one another other and are connected to one another in a flow-tight manner. The contact regions 13 rest directly against one another; a sealing element or any other component therebetween is not required. Each of the contact regions 13 is formed to be flat and extends with parallel spacing to the membrane plane so that, on the one hand, the spacing between adjacent membranes 8 is bridged via the profile section 12 and, on the other, the contact regions 13 arranged on top of one another rest against one another with a comparatively large surface area, which supports a flow-tight connection. The connection is implemented by welding, for example. In FIG. 2A, and enlarged view of the region 2A of FIG. 2 is shown. FIG. 2A shows a support grid or screen grid 18 fixedly welded between a foil 10 or 11 and the membrane 8, at least on one side of the membrane 8.

(13) Since the fresh air channels 4 and the exhaust gas channels 5 extend offset to one another at an angle of 90?, the edge regions of the membranes 8 are accordingly also provided with enclosing parts 9 which are offset at an angle of 90? and which seal the corresponding front ends at the channels. Enclosing parts are also located at the front ends of a channel, each of which front ends is offset by 90?; the foils 10 and 11 are also connected to one another at the front ends, e.g. by welding or adhesive bonding. Here, the bonded foils 10 and 11 together with a sealing strip, e.g. a plastic component or an adhesive tape, form the second axially offset channel.

(14) In the spaces between the membranes 8, which form the fresh air channels 4 and the exhaust gas channels 5, spacers 14 are inserted which extend directly between the membranes 8 and keep the membranes at a defined distance from one another.