DE102020130603A1 - Process for producing a membrane for a humidifier and for producing a humidifier - Google Patents

Abstract

The invention relates to a method for producing a membrane for a humidifier (2), comprising the following steps: a. Providing a spinneret (11) with a polymer solution (12) and a center liquid (13),b. activating the spinneret (11) and thereby forming a first intermediate product, c. transferring the intermediate product to a precipitation bath (14) and thereby precipitating a filament in the precipitation bath (14), d. drying the filament, e. producing a membrane from the filament by means of an additive manufacturing process (16), andf. Rinsing (17) and drying (18) the membrane. The invention also relates to a method for manufacturing a humidifier.

Description

The invention relates to a method for producing a membrane, in particular a porous membrane, for a humidifier. The invention also relates to a method for producing a humidifier for a fuel cell device.

Humidifiers are generally used in order to be able to transfer the moisture to the drier medium in two gaseous media with a different moisture content. Such gas/gas humidifiers are used in particular in fuel cell devices in which air is compressed with the oxygen it contains in the cathode cycle to supply the cathode chambers of the fuel cell stack, so that relatively warm and dry compressed air is present, the humidity of which is suitable for use in the fuel cell stack for the membrane electrode unit not enough. The dry air provided by the compressor for the fuel cell stack is humidified by being guided past a membrane permeable to water vapor, the other side of which is coated with the moist exhaust air from the fuel cell stack. For the conditioning of the air to be supplied to the cathode chambers of the fuel cell stack, it is also necessary to control the temperature thereof, for which purpose charge air coolers positioned downstream of the compressor are generally used. The humidifier and the intercooler are large components that contribute to a large increase in the space required for a fuel cell device and limit the efficiency of the fuel cell device because of the high thermal losses.

It should also be noted that the humidifiers known from the previous state of the art are complex to assemble, since they have a modular structure and the individual manufactured modules have to be sealed and braced against one another, so that the material costs for the seals and the tensioning system are high and there are inaccuracies during assembly can lead to an uneven distribution of the fluids in the humidifier.

Porous membranes for a humidifier, in particular hollow-fiber membranes, are usually produced by means of "potting" in a centrifuge or by means of a phase inversion process. In the case of the latter, a spinneret is provided with a polymer solution and a center liquid, which is activated so that a first intermediate product is produced, which is transferred to a precipitation bath and precipitated therein. The hollow filament produced in this way is rinsed over several rollers in a rinsing bath, then dried and wound. Disadvantages here are the comparatively time-consuming and therefore costly rinsing step, the size and the high cost of materials.

the WO 2016 / 135 385 A1 and the WO 2019 / 243 826 A1 describe a process in which membranes are printed from a filament using a generative process. The filament is produced using the phase inversion process described above.

the U.S. 2019/0 305 322 A1 describes a 3D printing process in which porous nanofilaments form a three-dimensional mesh to form an electrode.

It is therefore the object of the present invention to specify a method with which the production of a porous membrane and a humidifier can be simplified.

This object is achieved by a method having the features of claim 1 and by a method having the features of claim 3. Advantageous configurations with expedient developments of the invention are specified in the dependent claims.

1. a. Bereitstellen einer Spindüse mit einer Polymerlösung und einer Centerflüssigkeit,
2. b. Aktivieren der Spindüse und dadurch Ausbilden eines ersten Zwischenprodukts,
3. c. Überführen des Zwischenprodukts in ein Fällbad und dadurch Ausfällen eines Filaments in dem Fällbad,
4. d. Trocknen des Filaments,
5. e. Herstellen einer Membran aus dem Filament mittels eines generativen Fertigungsverfahrens, und
6. f. Spülen und Trocknen der Membran.

The method according to the invention for producing a porous membrane for a humidifier is characterized by the following steps:

1. a. providing a spinneret with a polymer solution and a center liquid,
2. b. activating the spinneret and thereby forming a first intermediate product,
3. c. transferring the intermediate product to a precipitation bath and thereby precipitating a filament in the precipitation bath,
4. i.e. drying the filament,
5. e. Manufacturing a membrane from the filament using an additive manufacturing process, and
6. f. Rinse and dry the membrane.

The membrane is made from the filament using a generative manufacturing process, preferably printed. The rinsing and drying step customary in phase inversion is omitted in the manufacture of the filament of the present invention. Instead, the generatively manufactured membrane is rinsed and dried. This speeds up and reduces the manufacturing process, since an additional rinsing step for the filament can be dispensed with. Cellulose acetate, polyacrylonitrile, poly(methyl methacrylate), polyamide or polysulfone resin is preferably used as the polymer solution.

It is advantageous if the dried filament is wound up before the membrane is produced.

• • Bereitstellen mindestens einer Spindüse mit einer Polymerlösung und einer Centerflüssigkeit,
• • Aktivieren der Spindüse und dadurch Ausbilden eines ersten Zwischenprodukts,
• • Überführen des Zwischenprodukts in ein Fällbad und dadurch Ausfällen eines Filaments in dem Fällbad,
• • Trocknen des Filaments,
• • Drucken eines ersten Befeuchtermoduls,
• • Drucken einer Membran aus dem Filament auf einer Oberfläche des ersten Befeuchtermoduls, oder Bereitstellen einer generativ aus dem Filament hergestellten Membran und Auflegen der Membran auf die Oberfläche des ersten Befeuchtermoduls, und
• • Spülen und Trocknen des ersten Befeuchtermoduls zusammen mit der Membran.

The method according to the invention for producing the humidifier is characterized by the following steps:

• • providing at least one spinneret with a polymer solution and a center liquid,
• • activating the spinneret and thereby forming a first intermediate product,
• • Transferring the intermediate product into a precipitation bath and thereby precipitating a filament in the precipitation bath,
• • drying the filament,
• • Printing a first humidifier module,
• • Printing a membrane from the filament on a surface of the first humidifier module, or providing a membrane produced generatively from the filament and placing the membrane on the surface of the first humidifier module, and
• • Rinsing and drying of the first humidification module together with the membrane.

The entire humidifier, ie both the first humidifier module and the membrane, can be produced using an additive manufacturing process, in which case an additional (intermediate) rinsing step of the filament can be dispensed with. This simplifies and reduces the production of the humidifier. At the same time, by using the generative manufacturing process, improved utilization of the installation space can be ensured by increasing the surface area, improved mechanical stability and improved heat and mass transfer. In addition, there is no need for "potting" in centrifuges. Subsequent assembly and thus seals or a clamping system can also be dispensed with.

The membrane and the first humidifier module can be generatively manufactured separately from one another, so that the generatively manufactured membrane is placed on the surface or in a recess formed on the surface of the generatively manufactured first humidifier module.

The first humidifier module and the membrane are preferably printed one after the other, so that the first humidifier module is printed first, with the membrane then being printed from the filament onto the surface of the first humidifier module.

In order to further speed up and simplify the manufacturing process, the first humidifier module and the membrane are particularly preferably printed in the same manufacturing step. The first humidifier module is printed using a first nozzle attached to a print head of the 3D printer, and the membrane is printed on the surface of the first humidifier module in the same manufacturing step using a second nozzle attached to the print head.

The performance of the humidifier can be scaled in a simple manner by using several membranes with associated humidification modules, with the method according to the invention offering the possibility that in a further generative manufacturing step on the first humidifier module and the membrane a second humidifier module and a second membrane are further printed and that the method steps are repeated iteratively up to a predetermined size of the humidifier with the desired number of humidifier modules.

In analogy to the production of the first humidifier module, the second humidifier module is preferably produced generatively in the same production step using the first nozzle attached to the print head and the second membrane using the second nozzle attached to the print head. This simplifies and speeds up the manufacture of the humidifier.

Alternatively, the second humidifier modules and the second membrane can also be generatively manufactured separately from one another. This means that the second humidifier module is printed on the first humidifier module and the membrane by means of the first nozzle and the separately produced membrane is placed on a surface or in a recess of the second humidifier module.

Alternatively, it is also possible for the second humidifier module to be printed onto the first humidifier module and the membrane using the first nozzle, with the membrane then being printed onto the surface using the second nozzle.

The first humidifier module and/or the second humidifier module is expediently designed as a flow field frame with an assigned flow field in which flow channels are separated from one another by webs. The webs are used to support the membrane and to guide the flowing fluids, and due to the type of manufacturing process used, the most varied shapes and configurations of the webs and thus the flow channels or the inlet and outlet lines can also be realized without any problems to. It is therefore possible to have bulges in which a liquid can accumulate, or, for example, constrictions to modify the flow rate.

It is also advantageous that the hose connections are formed on at least one end plate or on the edge on at least one side plate in a generative manufacturing step, i.e. the humidifier is created overall as a unit in the generative manufacturing process by a 3D printer, with a temperature-resistant plastic is used. PU, PA6 or PEEK can only be used as examples of such a temperature-resistant plastic.

The humidifier created in this way, with a plurality of membranes arranged between two humidifier modules, is free of seals and a clamping system, whereby the design can also be freely selected within wide limits, i.e. better adaptation to the installation conditions is provided if this humidifier is used as a Part of a fuel cell device used in a motor vehicle.

It should also be noted that the humidifier modules are designed as flow field frames with assigned flow fields in which flow channels are separated by webs and the contour and/or course of the flow channels, the webs separating them and/or the flow channels feeding the supply lines due to their position and function is determined by using a narrowing of the contour to influence the flow rate and a bend in the flow rate to influence the separation and/or storage of water.

The features and combinations of features mentioned above in the description and the features and combinations of features mentioned below in the description of the figures and/or shown alone in the figures can be used not only in the combination specified in each case, but also in other combinations or on their own, without going beyond the scope of the leave invention. Embodiments are therefore also to be regarded as included and disclosed by the invention which are not explicitly shown or explained in the figures, but which result from the explained embodiments and can be generated by means of separate combinations of features.

• 1 eine schematische Darstellung einer Brennstoffzellenvorrichtung,
• 2 eine schematische Darstellung des Verfahrens zur Herstellung einer porösen Membran, und
• 3 eine schematische Darstellung des Verfahrens zur Herstellung eines Befeuchters.

Further advantages, features and details of the invention result from the claims, the following description of preferred embodiments and with reference to the drawings. show:

• 1 a schematic representation of a fuel cell device,
• 2 a schematic representation of the process for the production of a porous membrane, and
• 3 a schematic representation of the method for producing a humidifier.

In the 1 a fuel cell device 1 is shown schematically, this comprising a humidifier 2 for humidity regulation of a plurality of fuel cells 4 combined in a fuel cell stack 3 .

Each of the fuel cells 4 comprises an anode, a cathode and a proton-conductive membrane separating the anode from the cathode. The membrane is formed from an ionomer, preferably a sulfonated polytetrafluoroethylene polymer (PTFE) or a polymer of perfluorinated sulfonic acid (PFSA). Alternatively, the membrane can also be formed as a sulfonated hydrocarbon membrane.

A catalyst can also be added to the anodes and/or the cathodes, the membranes preferably being coated on their first side and/or on their 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 a reaction accelerator in the reaction of the respective fuel cell.

Fuel (e.g. hydrogen) can be supplied to the anode via an anode chamber. 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 lets the protons through but is impermeable to the electrons. At the anode, for example, the reaction takes place: 2H ₂ → 4H ⁺ + 4e ^- (oxidation/donation of electrons). While the protons pass through the PEM to the cathode, the electrons are conducted to the cathode or an energy storage device via an external circuit.

The cathode gas (for example oxygen or air containing oxygen) can be fed to the cathode via a cathode space, so that the following reaction takes place on the cathode side: O ₂ + 4H ⁺ + 4e ^- → 2H ₂ O (reduction/electron acceptance).

Since several fuel cells 2 are combined in the fuel cell stack 3, a sufficiently large quantity of cathode gas is made available, so that a large cathode gas mass flow or fresh gas flow is made available by a compressor 5, with the temperature of the cathode gas increasing sharply as a result of the compression of the cathode gas. The conditioning of the cathode gas or the fresh air gas flow, i.e. its setting with regard to the temperature and humidity desired in the fuel cell stack 3, takes place in a charge air cooler (not shown in detail) downstream of the compressor and in the humidifier 2, which saturates the membranes of the fuel cells 4 with moisture to increase their efficiency causes, since this favors the proton transport.

On the anode side, the fuel cell stack 3 is fluid-mechanically connected to an anode feed line, so that fuel contained in the fuel storage device 6 shown schematically can be fed to the fuel cell stack 3 . A valve or an ejector pump can be suitable in order to realize the desired partial pressure of fresh fuel within the anode circuit, which comes about through the anode recirculation line. With such an anode recirculation line, the fuel not consumed in the fuel cell stack 3 can be fed back to the anode chambers upstream of the fuel cell stack 3, so that the anode recirculation line opens back into the anode feed line. In order to discharge the liquid from the anode circuit, a separator 7 is integrated into the anode recirculation line. This is fluid-mechanically connected to the cathode side of the fuel cell device 1 so that the liquid occurring on the anode side is introduced, for example, into the cathode exhaust gas line 8 downstream of the fuel cell stack 3 in order to discharge the liquid, for example, from the fuel cell device 1 . Alternatively or additionally, the liquid occurring on the anode side can also flow from the separator 7 into a cathode feed line 9 upstream of the humidifier 2 so that the liquid is introduced into the fresh cathode gas there before it reaches the humidifier 2 . This has the advantage that the humidifier 2 can be made smaller overall, since the fresh fresh gas, which has been dried by the compression by means of the compressor 5, then no longer has to be humidified so much in order to ensure the required humidity of the membranes in the fuel cell stack 3.

In order to be able to regulate the mass flow of the cathode gas through the fuel cell stack 3, there is a bypass 10 which has an actuator, in particular a pressure control valve. This bypass 10 connects the cathode supply line 9 to the cathode exhaust line 8.

2 shows a schematic representation of a method for producing a porous membrane for the humidifier 2. First, a spinneret 11 fed by a polymer solution 12 and a center liquid 13 is provided. The spinneret 11 is activated, as a result of which a first intermediate product, in this case a hollow fiber, is formed. The intermediate product is transferred to a precipitation bath 14, whereby a filament is precipitated. The filament is then dried and wound onto a spool 15 in an optional step. The porous membrane is then produced or printed by means of an additive manufacturing process 16; eg using a 3D printer. Finally, the membrane is rinsed 17 in a rinsing device and dried 18 in a drying device. The production of the membrane by means of a generative manufacturing process 16 allows a reduction in the structural size of the membrane and thus also a reduction in the cost of materials. In addition, an additional rinsing step of the filament before the generative manufacturing step 16 can be dispensed with, so that one step can be saved in the manufacture of the membrane.

The method according to the invention is therefore simpler, faster and cheaper.

3 shows a schematic representation of a method for producing the humidifier 2. For this purpose, the filament is first produced, as in 2 already described. A first humidifier module is now preferably printed by means of the additive manufacturing method 16 by means of a first nozzle of a print head. In the same manufacturing step, a membrane is printed from the filament onto the surface of the first humidifier module using a second nozzle attached to the print head. In a further generative manufacturing step 16, a second humidifier module is printed on the first humidifier module and the membrane by means of the first nozzle and a second membrane by means of the second nozzle. The method steps can be repeated iteratively up to a predetermined size of the humidifier 2 with the desired number of humidifier modules. Once the specified size of the humidifier 2 has been reached, the humidifier 2 composed of the humidifier modules and the membranes is rinsed 16 and dried 17 in two final steps.

In an alternative embodiment that is not shown in detail, the membrane or membranes, as in 2 described, manufactured separately from the humidifier modules and provided for the manufacture of the humidifier 2. Thus, the first humidifier module is generatively manufactured or printed 16. A simultaneously or previously produced The membrane provided is provided and placed on the surface of the first humidifier module or in a recess formed on the surface of the first humidifier module. The second humidifier module is then printed onto the first humidifier module and the membrane. Then in turn a provided second membrane is placed on the surface or in the recess of the second humidifier module. These steps are repeated iteratively up to a predetermined size of the humidifier 2 with the desired number of humidifier modules. Once the specified size of the humidifier 2 has been reached, the humidifier 2 composed of the humidifier modules and the membranes is rinsed 16 and dried 17 in two final steps.

The humidifier modules are preferably produced additively from a temperature-resistant polymer 19 . In addition, the humidifier modules or individual humidifier modules can be designed as a flow field frame with an assigned flow money, in which flow channels are separated from one another by webs. In addition, the hose connections can be formed on at least one end plate or on the edge on at least one side plate in a generative manufacturing step during the manufacture of the humidifier modules.

Reference List

1

fuel cell device

2

humidifier

3

fuel cell stack

4

fuel cell

5

compressor

6

fuel

7

separator

8th

cathode exhaust line

9

cathode supply line

10

bypass

11

spinneret

12

polymer solution

13

center fluid

14

precipitation bath

15

Kitchen sink

16

Additive manufacturing process (e.g. 3D printing)

17

Wash

18

dry

19

polymer

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

• WO 2016/135385 A1 [0005]
• WO 2019/243826 A1 [0005]
• US 2019/0305322 A1 [0006]

Claims (10)

Method for manufacturing a membrane for a humidifier (2), comprising the following steps: a. Providing a spinneret (11) with a polymer solution (12) and a center liquid (13), b. activating the spinneret (11) and thereby forming a first intermediate product, c. Transferring the intermediate product to a precipitation bath (14) and thereby precipitating a filament in the precipitation bath (14), i.e. drying the filament, e. producing a membrane from the filament by means of an additive manufacturing process (16), and f. rinsing (17) and drying (18) the membrane. procedure after claim 1 , characterized in that the dried filament is wound up (15) before the membrane is manufactured. Method for producing a humidifier (2) for a fuel cell device (1), comprising the following steps: • providing at least one spinneret (11) with a polymer solution (12) and a center liquid (13), • activating the spinneret (11) and thereby forming a first intermediate product, • Transferring the intermediate product into a precipitation bath (14) and thereby precipitating a filament in the precipitation bath (14), • drying the filament, • Printing a first humidifier module, • Printing a membrane from the filament on a surface of the first humidifier module, or providing a membrane produced generatively from the filament and placing the membrane on the surface of the first humidifier module, and • Rinsing (17) and drying (18) the first humidifier module together with the membrane. procedure after claim 3 , characterized in that the first humidifier module is printed by means of a first nozzle attached to a print head, and that the membrane is printed in the same manufacturing step by means of a second nozzle attached to the print head on the surface of the first humidifier module. procedure after claim 3 or 4 , characterized in that in a further generative manufacturing step on the first humidifier module and the membrane, a second humidifier module and a second membrane are further printed, and that the process steps are repeated iteratively up to a predetermined size of the humidifier (2) with the desired number of humidifier modules will. procedure after claim 5 , characterized in that the second humidifier module is produced generatively by means of a first nozzle attached to the print head and the membrane by means of a second nozzle attached to the print head in the same production step. Procedure according to one of Claims 5 or 6 , characterized in that the first humidifier module and/or the second humidifier module is designed as a flow field frame with an assigned flow field in which flow channels are separated from one another by webs. Procedure according to one of Claims 5 until 7 , characterized in that the hose connections are formed on at least one end plate or at the edge on at least one side plate in an additive manufacturing step. Procedure according to one of Claims 5 until 8th , characterized in that the humidifier modules are produced additively from a temperature-resistant polymer. Procedure according to one of claims 3 until 9 , characterized in that the dried filament is wound up (15) before the membrane and/or the humidifier module is printed.

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