DE202014006480U1 - humidifier - Google Patents

Abstract

A humidifier (3), in particular for humidifying process gas for fuel cells, comprising: - a first input (5) for supplying dry gas and a first outlet (6) for discharging humidified gas, - a second inlet (7) for supplying humid gas and a second outlet (8) for delivering dehumidified gas, - at least a first (12) and a second (14) flow plate, - a water transfer medium (15) disposed between the first (12) and second flow plates (14) operating gas impermeable or substantially gas impermeable, wherein the first (12) and the second flow plate (14) each have channels (13, 17) for guiding gas, characterized in that the channels (13, 17) along their main extension direction in each case a plurality of Leitgeometrien formed so as to be perpendicular to the plane of plan plane of the respective flow plate (12, 14) a disorder of the ideal linear laminar effecting the flow of gas carried in the channel.

Description

The present application relates to a humidifier, preferably for the humidification of process gas for fuel cells.

Fuel cells use, among other things, process gases, for example, molecular hydrogen and / or oxygen for power generation. Such fuel cells typically use proton exchange membranes (PEMs). In operation, such a PEM heats up to about 80 ° C to 90 ° C. It is important for the efficiency of the fuel cell as well as for the durability of the PEM, that in terms of temperature and humidity in the area of the PEM stationary conditions prevail as possible. In particular, drying out of the PEM can adversely affect the durability and efficiency of the fuel cell.

For specific adjustment of the degree of moisture of the process gases supplied to the fuel cell, it is therefore customary to moisten certain process gases before these are supplied to the fuel cell. For this purpose, humidifiers are usually used in which a water transfer medium is arranged between two flow plates provided with channel structures, typically in the form of a water-permeable membrane. The water permeable membrane is also referred to as a water transfer membrane or as a transfer membrane. This transfer membrane separates a dry or humidified gas stream guided in the channel structures of the first flow plate from a humidified or dehumidified gas stream in the channel structures of the second flow plate, wherein a moisture level of the wet gas stream is higher than a moisture level of the dry gas stream. Then a transfer of water from the moist gas stream to the dry gas takes place via the transfer membrane, so that the moisture levels of the gases on both sides of the membrane equalize. Due to the fact that the transfer membrane is substantially gas-tight (at least for a minimum moistening), the moisture degree of the two gases or gas streams in the moistener approximates, without the gases themselves being mixed.

The transfer membrane of the humidifier normally causes a significant proportion of the material costs incurred in the manufacture of the humidifier. To reduce the material costs there is therefore a need for humidifiers with a transfer membrane of reduced area with as constant as possible humidifier performance.

The present invention is therefore based on the object to provide a humidifier in which the water transfer is increased over a given area of the transfer membrane over known humidifiers.

This object is achieved by a humidifier according to claim 1. Special Ausführungsausformen are described in the subclaims.

• – einen ersten Eingang zum Zuführen trockenen Gases sowie einen ersten Ausgang zum Abgeben befeuchteten Gases,
• – einen zweiten Eingang zum Zuführen feuchten Gases sowie einen zweiten Ausgang zum Abgeben entfeuchteten Gases,
• – mindestens eine erste und eine zweite Strömungsplatte,
• – ein zwischen der ersten und der zweiten Strömungsplatte angeordnetes Wassertransfermedium, das im Betrieb gasundurchlässig oder im Wesentlichen gasundurchlässig ist,

wobei die erste und die zweite Strömungsplatte jeweils Kanäle zur Gasführung aufweisen.Thus, a humidifier is proposed, in particular for humidifying process gas for fuel cells, comprising:

• A first input for supplying dry gas and a first outlet for delivering humidified gas,
• A second inlet for supplying moist gas and a second outlet for delivering dehumidified gas,
• At least a first and a second flow plate,
• A water transfer medium disposed between the first and second flow plates which is gas impermeable or substantially gas impermeable in use,

wherein the first and second flow plates each have channels for gas guidance.

The proposed humidifier is distinguished from the known generic humidifiers in that the channels of at least one of the flow plates along their main extension direction each have a plurality of Leitgeometrien which are formed such that they perpendicular to the plane plane of the respective flow plate a disturbance of an ideal linear laminar flow of the effect in the channel guided gas.

In the ideal linear laminar flow, the flow lines along the flow direction are ideally stratified and undisturbed. As a result of the disturbance caused by the Leitgeometrien can in the respective channel z. As a parallel laminar flow or a disturbed laminar flow arise, especially in the region of the respective guide geometry. In the case of the parallel laminar flow, the flow lines are aligned parallel to one another along the flow direction and possibly follow the contour of the channel, if it is corrugated, for example. In the disturbed laminar flow, although the flow lines typically remain aligned, the ideal stratification is disturbed. In this case, z. As a helical rotation or compression of the gases in the channel.

The present invention is based on the finding that the water transfer via the water transfer medium in known humidifiers is impaired primarily by the fact that the water transfer on both sides of the water transfer medium in the channels the flow plates guided gas flows substantially linear laminar, that is flow in layers. Typically, these flow layers are aligned parallel to the plane of plan plane of the flow plates or parallel to the plane of plan plane of the water transfer medium disposed between the flow plates.

Hereinafter, a first side of the plane surface plane of the water transfer medium, are arranged at the channels for guiding wet or to be dehumidified gas, also wet side of the water transfer medium. Accordingly, the second side of the plane surface plane of the water transfer medium opposite the wet side of the water transfer medium, on which channels for guiding dry or to be humidified gas are arranged, should be referred to as the dry side of the water transfer medium.

The water transfer rate of the water transfer medium, d. H. the amount of water transferred per unit time per unit area of the water transfer medium from the wet side of the water transfer medium to the dry side of the water transfer medium usually increases with increasing moisture gradient between the wet and dry sides of the water transfer medium, especially with increasing moisture gradient between the tops of both sides of the water transfer medium Channels or the gas guided therein. The tops of the channels should be the water transfer medium respectively facing sides or areas of the channels, no matter whether they are in the specific arrangement above or below.

In known humidifiers, a comparatively good exchange of moisture usually takes place only between the upper sides of the channels on both sides of the water transfer medium or between the flow layers guided on the upper sides of the channels on the moist side of the water transfer medium on the one hand and on the dry side of the water transfer medium on the other hand. However, due to the laminar flow profiles in the individual channels, moisture equalization perpendicular to the planar surface plane of the flow plates hardly takes place in one and the same channel for guiding wet gas or in one and the same channel for guiding dry gas. This typically results in the moisture levels in the flow layers at the top of the channels rapidly aligning on either side of the water transfer medium. This reduces the moisture gradient between the wet and dry sides of the water transfer medium. This is accompanied by a reduction in the water transfer rate.

The inventors of the humidifier proposed herein have recognized that the water transfer rate can be significantly increased if the channels on the wet side of the water transfer medium and / or the channels on the dry side of the water transfer medium are provided with the said guide geometries. From the foregoing, it will be readily apparent to one skilled in the art that disturbance of the ideally linear laminar flow acting perpendicular to the plane surface plane of the respective flow plate will improve the moisture transfer within one and the same channel. Thus, a sufficiently large moisture gradient can be maintained between the areas of the wet and dry sides of the water transfer medium which are close to the water transfer medium. In this way, the water transfer rate is permanently increased in a simple and efficient manner. Essential to the invention and thus the optimal operation of the humidifier is that the ideal linear laminar flow is disturbed, but not to the extent that a turbulent flow would result.

The main extension direction of the channel denotes the direction along which a macroscopic mass transport of the channel-guided gas through the channel takes place in the time average. The main direction of extension of the channel is not necessarily given by a straight line. The channels may extend in a straight, wavy, or otherwise curvilinear manner parallel to the planar surface plane of the respective flow plate, typically each about a length of about 10 to 45 cm.

The guide geometries are normally distributed uniformly along the main extension direction of the channels, for. B. at regular intervals. Typically, one and the same channel along its main extension direction has at least two, at least three, at least five or at least ten guide geometries of the type described in more detail below.

The channels are usually bounded by channel walls. These typically include channel sidewalls aligned perpendicularly or substantially perpendicular to the planar surface plane of the respective flow plate, and a channel bottom. The channel bottom is normally aligned parallel or substantially parallel to the plane plane of the respective flow plate. The wording "essentially" can be z. B. deviations from the parallelism or orthogonality of up to 30 °, of up to 20 °, of up to 10 ° or of up to 5 °. The channel walls bound the channel to the flow plate.

For the water transfer medium, the channels are usually limited by the water transfer medium itself or by a support medium disposed between the water transfer medium and the respective flow plate. The support medium can be, for example, a (graphite) fiber paper, a (graphite) fiber fabric, a nonwoven or other fabric or scrim of natural and / or synthetic fibers. The support medium is usually gas permeable. The water transfer medium may, for. As a porous medium, a coated or impregnated fabric ^(® Texapore, Venturi ^®), be a membrane laminate (Goretex ^®), an ion-impregnated membrane, an ionomer membrane (Nafion ^®) or a diaphragm. At least on the low pressure side of the water transfer medium, that is on the side of higher moisture content, a support medium is usually always required, but usually it is arranged on both sides of the water transfer medium.

The flow plates are usually at least partially formed of corrosion-resistant metallic materials, in particular stainless steel. Likewise, thermoplastic, elastomeric or thermosetting plastics can be used. Typically, the channel structures of the flow plates are impressed into the corresponding surfaces of the flow plates during manufacture. This makes it easy to produce large quantities. Alternatively, the flow plates can be made by injection molding, wherein the channels are mitgeformt directly. This provides more freedom in channel design. For polymer materials, a special form of injection molding offers an injection-embossing process.

Normally, the humidifier comprises a plurality of flow plates, wherein between each two of these plates a water transfer medium of the type mentioned is arranged. For guiding liquid or gaseous media in the stacking direction, typically for guiding process gas for a fuel cell stack, the flow plates can have openings which, when stacking the flow plates, at least one, preferably exactly one line for guiding moist gas, at least one, preferably exactly one line to Lead dehumidified gas, at least one, preferably exactly one line for guiding dry gas and at least one, preferably form a line for guiding humidified gas. Usually, the first inlet of the humidifier for supplying dry gas is connected via one of the lines for guiding dry gas, via the channels arranged on the dry side of the water transfer medium and via one of the lines for guiding humidified gas to the first outlet of the humidified humidifier , Likewise, the second inlet of the humidifier humidifier is usually via one of the humid gas ducts, the channels disposed on the wet side of the water transfer medium, and one of the ducts for feeding dehumidified gas to the second outlet of the humidifier dehumidified gas connected.

The channels of the first flow plate for guiding the moist gas and the channels of the second flow plate for guiding the dry gas may be at least partially parallel or substantially parallel to each other. They can each be flowed through in the same direction or in the opposite direction. The channels for guiding the moist gas and the channels for guiding the dry gas may also be arranged obliquely to each other. This allows you to enclose an angle with each other that is essentially 0 °, 90 ° or 180 °. Here and in the following, all angles are given in the angular dimension. At 0 ° results in a DC arrangement, at 90 °, a cross-flow arrangement and at 180 °, which corresponds in terms of the channel guide as such, the 0 ° orientation, a countercurrent arrangement.

In a specific embodiment of the proposed humidifier, the guide geometries comprise elongate recesses formed in at least one of the channel walls and / or elongate protrusions arranged on at least one of the channel walls and protruding into the respective channel. The elongate recesses or the elongate projections preferably include an acute angle α with a center line of the respective channel wall extending along the main extension direction of the channel. For this z. For example, 45 degrees ≤ α ≤ 70 degrees. The channel wall with the recesses and / or projections may be one of the channel side walls or the channel bottom.

Characterized in that the elongated recesses or the elongated projections with the center line of the respective channel wall form an acute angle, they give the flow direction of the gas flowing in the channel, a velocity component perpendicular to the main flow direction of the gas in the channel. This causes the desired disruption of the ideally linear laminar flow of the gas, perpendicular to the plane of the plane of the flow plate, thereby improving water exchange across the water transfer medium. The elongated recesses and / or projections may be arranged, for example, such that the flow of the gas follows a spiral course along the main extension direction of the channel. Similar guide geometries are z. B. of rifle barrels, the a cartridge accelerated in the rifle barrel impart an angular momentum or spin aligned parallel to the rifle barrel. The various recesses and / or projections in the channel are preferably to be arranged such that they each impart a twist to the gas flow with the same direction of rotation.

A cross-sectional area of the recesses, which is perpendicular to the length or to the longitudinal direction of the recesses, can each be between 2 and 12 percent, preferably between 2 and 10 percent, of a cross-section of the channel. Preferably, the cross-section of the channel to which the cross-sectional area of the recesses is related is the smallest cross-section along the entire passageway. With regard to this smallest cross section, the cross section of the channel in the region of the recesses is thus typically increased by between 2 and 12 percent, preferably by between 2 and 10 percent. A cross-sectional area of the projections, which is perpendicular to the length or to the longitudinal direction of the projections, can likewise each amount to between 2 and 12 percent, preferably between 2 and 10 percent, of the cross-section of the channel. Preferably, the cross-section of the channel to which the cross-sectional area of the projections is related is the largest cross-section along the entire passageway. With regard to this largest cross section, the cross section of the channel in the region of the projections is thus typically reduced by between 2 and 12 percent, preferably by between 2 and 10 percent.

It has been found that recesses or protrusions of these dimensions are capable of achieving the desired perturbation of the ideal linear laminar flow perpendicular to the plane of plan plane of the respective flow plate without overly affecting the main flow of the gas in the channel along the main direction of extension of the channel ,

Perpendicular to the plane plane of the respective flow plate, a height of the projections and / or a depth of the recesses is preferably less than 40 percent of a depth of the channel defined perpendicular to the plane of the plane of the flow plate. Particularly preferably, the height of the projections and / or the depth of the recesses are between 10 and 25 of the depth of the channel. Preferably, the depth of the channel, to which the depth of the recesses or the height of the projections is set, is a smallest depth of the channel along the entire channel course. With regard to the change in the cross section in the region of the recesses or in the region of the projections caused by the recesses and / or the projections, the above applies.

Immediately succeeding recesses and / or projections along the main extension direction of the channel are preferably arranged such that their facing ends do not overlap parallel to the cross section of the channel and are preferably spaced apart. Preferably, immediately adjacent recesses and / or projections along the main extension direction of the channel are aligned and arranged such that they each impart a twist with the same direction of rotation with respect to a central axis of the channel to the gas flowing in the channel.

In a further embodiment, the guide geometries along the main extension direction of the channel extending and merging channel sections of the channel, wherein a cross section of the channel along the channel sections in each case in the same direction decreases or increases and wherein the transition between two of the merging channel sections each via a Edge takes place. For example, the cross-section along a first channel portion continuously decreases to abruptly increase at a first edge. At the first edge, the first channel section then merges into a second channel section. Normally, the second channel portion is formed as well as the first channel portion. The cross section of the second channel section thus typically decreases continuously again starting from the first edge, in order to abruptly increase again at a second edge, and so on. The abrupt enlargement of the cross section at the edges between successive channel sections thus normally compensates for the previously occurring slower reduction of the cross section along the channel sections. Of course, along the channel sections, a slow enlargement of the cross section can take place, which is then compensated by a corresponding abrupt reduction of the cross section in the region of the edges arranged between the channel cross sections.

In other words, in this embodiment the guiding geometries comprise a plurality of edges formed in at least one of the channel side walls and / or the channel bottom, the cross section of the channel either decreasing or increasing in each case in the same direction between two consecutive edges along the main extension direction of the channel.

The edge can be a blunt edge that makes an angle greater than 90 °. Usually, however, the angle formed by the edge is at most 110 ° or at most 100 °. The edge may also form a right angle at which the cross section of the channel changes discontinuously. It is even conceivable that the Angle is slightly less than 90 °, but typically at least 80 ° or at least 85 °. After reducing the cross-section, it is preferable to increase, but it is also possible that the structure always alternates two reductions and two magnifications. It is also conceivable that a channel section with decreasing or increasing cross section at a corresponding edge merges into a straight channel section with a constant cross section. An edge is not necessarily to be understood in terms of a sharp edge, but preferably has a radius - also depending on the selected material - usually from 0.05 mm to 1 mm.

It is crucial in each case that changes the cross section at the edge between two of the merging sections as abruptly as possible, ie increased or decreased. As a result, the desired, linear laminar flow in the channel, which is perpendicular to the planar surface plane of the respective flow plate, is produced at the edge.

For the change of the cross-section of the channel at said edges, with respect to the smallest cross-section A _min and the largest cross-section A _max in the region of the edge normally (A _{max -A min} ) / A _min ≤ 1, preferably 0.75 ≤ (A _max - A _min ) / A _min ≦ 1, particularly preferably 0.8 ≦ (A _{max -A min} ) / A _min ≦ 1. Alternatively or additionally, normally (A _{max -Amin} ) / A _min ≦ 0.98. The smallest or largest cross section A _min and A _max in the region of the edge are preferably to be understood that one of these two cross sections, ie z. B. the smallest cross section A _min (the largest cross section A _max ) is located directly on the edge, while the corresponding other cross section so here the largest cross section A _max (the smallest cross section A _min ) the nearest largest or smallest cross section in the positive or negative channel is. Along the main span direction of the channel, the distance between two consecutive edges is typically at least 100 percent, or at least 200, of a mean or maximum depth of the channel, or a mean or maximum width of the channel. A maximum distance between two consecutive edges may be up to five times or up to ten times the mean depth or width of the channel. As before, the average depth and the mean width of the channel are determined perpendicular or parallel to the plane plane of the respective flow plate.

The channel sections are typically formed at least in regions by at least one channel side wall, which has a sawtooth-like profile parallel to the planar surface plane of the respective flow plate. Preferably, the channel sections are at least partially formed on both sides by channel side walls with a corresponding sawtooth. Alternatively or additionally, the channel sections may at least partially be formed by a channel bottom, which has a sawtooth-like profile perpendicular to the plane plane of the respective flow plate. The steep or steeper flanks of the saw-toothed profile or sawtooth profiles of the channel sidewalls and / or the channel bottom then typically form the edges between the channel sections. The corners of the "saw-toothed profile" or the "saw-toothed profiles" do not necessarily have to be pointed. They can certainly be at least partially rounded. Decisive again is that the cross section of the channel in the area formed by the "saw teeth" as described above abruptly changes, so that at the edges of the desired, acting perpendicular to the plane plane of the respective flow plate disturbances of the ideal linear laminar flow in the channel occur.

The sawtooth-like profile or sawtooth profiles of the channel side walls and / or the channel bottom may be periodic along the main direction of extension of the channel. For a period length λ _{S of} the sawtooth-like profile and a width B of the channel determined parallel to the plane surface plane of the respective flow plate, it is then preferably 5 * B ≦ λ _S ≦ 20 * B, particularly preferably 10 * B ≦ λ _S ≦ 15 * B. The width B can z. B. be a maximum width or an average width of the channel.

In another embodiment, the channel bottom of the channel and one of the channel bottom adjoining the channel side walls include an angle β, which changes along the main extension direction of the channel at least in sections. For the angle β, in each case preferably: 90 ° ≦ β ≦ 120 °. At a given point along the main extension direction of the channel, the angle β is z. B. in each case to determine in the plane in which the cross-sectional area of the channel assumes the smallest value. The angle β can change continuously at least in sections. Alternatively or additionally, the angle β may change discontinuously at at least one point, with an edge again forming in the channel side wall.

The guide geometries in this embodiment thus comprise a change in the inclination of the channel side wall relative to the channel bottom along the main extension direction of the channel described by the change in the angle β. Thereby, the flow of the gas in the channel along the main extension direction of the channel is normally both parallel and perpendicular to Planar plane of the respective flow plate deflected and changed. Thereby, also in this embodiment, perpendicular to the plane plane of the flow plate, the intended disturbance of the ideally linear laminar flow of the gas in the channel is created, which improves the gas exchange in the channel along this direction, so that the moisture transport in the direction of the water transfer medium is improved.

A further development envisages that both of the channel side walls adjoining the channel bottom change their inclination relative to the channel bottom along the main extension direction of the channel at least in sections at the same time, as described by angles β ₁ and β ₂ . As before, the angles β ₁ and β ₂ at a given location along the main direction of extension of the channel are e.g. B. in each case to determine in the plane in which the cross-sectional area of the channel assumes the smallest value. The portion in which the inclinations of the channel side walls with respect to the channel bottom change continuously, extending along the main extension direction of the channel z. At least 25 percent, at least 50 percent, at least 2/3 or at least 75 percent of a total length of the channel. The inclination angles β ₁ and β ₂ can thereby change continuously and / or discontinuously. The angles of inclination β ₁ and β ₂ preferably change in such a way that the cross section of the channel in this section changes by less than 60 percent, particularly preferably by less than 30 percent. On the other hand, the inclination angles β1 and β2 preferably change such that the cross section of the channel in this section changes by more than 5 percent, more preferably by more than 10 percent.

In a further embodiment, the guiding geometries comprise a depth of the channel varying along the main direction of extension of the channel. As before, the depth of the channel is determined perpendicular to the plane plane of the respective flow plate. For example, it is given by the distance from the channel bottom to the water transfer medium. The channel depth may also be given by the distance from the channel bottom to a support medium, which is arranged between the flow plate and the water transfer medium. A difference between a maximum channel depth and a minimum channel depth of the same channel is preferably less than 40 percent of the maximum channel depth, particularly preferably between 10 and 25 percent of the maximum channel depth. The change of the channel depth can be done at least in sections continuously. The person skilled in the art immediately learns that this too causes a disturbance of the ideally linear laminar flow in the channel, which is perpendicular to the planar surface plane of the respective flow plate.

Preferably, the channel depth in this embodiment changes at least in sections wavelike, z. B. at least in sections periodically. For example, for a period length λ _T, the change of the channel depth along the main direction of extension of the channel and for a width B of the channel determined parallel to the plane plane of the respective flow plate may be: 5 * B ≤ λ _T ≤ 20 * B, preferably 10 * B ≤ λ _T ≤ 15 · B. The width B can z. B. be a maximum or an average width of the channel.

The change in the cross-section of the channel normally associated with the change in the channel depth may, in particular, result in gas flowing in a first channel provided with a corresponding bump via a web which separates the first channel from a second channel adjacent to the first channel the same flow plate is separated, is pressed into this second channel. This is typically the case when the gas-permeable support medium described above is arranged between the flow plate and the water transfer medium. The gas exchange between adjacent channels of the same flow plate is then usually via or through the support medium. Of course, gas exchange between adjacent channels of the same flow plate will result in a particularly effective disruption of the ideally linear laminar flow in these channels, perpendicular to the plane of the plane of the flow plate.

In order to increase this effect, it can be provided, in particular, that two adjacent and mutually parallel channels of the same flow plate are each equipped with a periodic bump of the type described above. For example, the bumps of the adjacent channels may have the same period length λ _T. In this case, especially between the adjacent channels gas is exchanged when the periods of the bumps of the adjacent channels are shifted from each other, for. B. by a length Δλ _T , for which applies: λ _T / 3 ≤ Δλ _T ≤ 2 · λ _T / 3, preferably Δλ _T = λ _T / 2.

Typically, the channels of the flow plates are bounded by webs transverse to their respective main direction of extent. It can be provided that at least one of the flow plates has both straight webs and corrugated webs. Usually, a thickness of these webs varies along the direction of extension of the respective web by less than 50 percent, by less than 30 percent or by less than 10 percent. Preferably, the thickness of these webs along its direction of extension at least partially constant or continuously constant. The corrugated webs can be waved periodically be. A wavelength λ _{W of} these periodically corrugated webs may, for example, be given approximately by the maximum channel width B _max determined along the main extension direction of the channels. So z. B. B _max ≤ λ _W ≤ 2 · B _max . It is particularly advantageous if the straight webs and the corrugated webs are arranged alternately. For example, the webs can then be arranged such that the sum of the cross sections of two immediately adjacent channels along the main extension direction of the channels is approximately constant. This then typically involves the cross section of a first of the immediately adjacent channels decreasing as the cross section of the second of the immediately adjacent channels increases, and vice versa. Similar to the example described above, in which adjacent channels have periodic bumps with staggered periods, such an arrangement can promote gas exchange between the immediately adjacent channels, which positively influences the water transfer rate of the water transfer medium as described.

The guiding geometries may also comprise dome-shaped elevations arranged on the channel bottom and / or on the channel side walls. These can be z. B. are combined with the embodiment described above, are arranged in the straight and corrugated webs alternately on the flow plate. The dome-like projections may be arranged at regular intervals along the main extension direction of the channel. Typically, arranged on the channel bottom dome-like elevations with respect to the channel width are arranged approximately centrally. However, they can also be arranged away from the middle of the channel near one of the channel side walls. Preferably, the dome-like elevations in the flow direction are each arranged behind the region of maximum channel width, so that they bring about a particularly effective reduction of the channel cross section. The dome-like elevations may have different geometries. For example, they may have a round, oval or rounded-polygonal basic shape in plan view; the cross section can z. B. square, rounded-triangular, or otherwise be rounded, the rounded side has at least partially in the direction of the water transfer medium. In particular, it has proved to be advantageous if these dome-like elevations or at least one of them in its extension in the main extension direction of the channel in question and / or transversely to this has a changing height, as a result, the gas carried can particularly effectively impart a twist.

The dome-like projections used in combination with webs between the channels, they may all have a lower height than the webs, which extend to the support structure or - if one does not exist - the water transfer medium, they may differ in height with each other and the height of a dome-like elevation does not have to remain the same over its entire area. The height of the dome-like elevations is preferably between 20 and 50 percent of the height of the webs. However, if the dome-like elevations are deployed on a flow plate without additional elongated lands, at least a portion of the dome-like elevations must reach the support structure or, if one is absent, the water transfer medium.

In a further embodiment, the guide geometries can also comprise different heights of channel-limiting webs, in particular on the high-pressure side of the water-transfer medium, ie on its dry side. For this purpose, webs may, for example, have a wave-shaped course of their heights, sections may even be reduced to a height of 0. In principle, it is conceivable to make all channel-limiting webs wavy, in particular with phase-shifted waves at each other nearest webs, but it is preferred for stability reasons and in terms of durability of the membrane, if only a portion of the webs, for example, every other web, one about its course has varying height.

Of course, the various guiding geometries described here can be combined with each other. One and the same channel can therefore have guide geometries of different types. For example, one and the same channel may have an at least partially wave-like channel bottom as well as channel side walls with at least partially changing inclination relative to the channel bottom. Likewise, channel side walls with at least partially changing inclination simultaneously have a sawtooth-like profile parallel to the planar surface plane of the flow plate. Likewise, in these embodiments, recesses and / or projections for at least partially redirecting the gas flowing in the channel can be provided in or on the channel walls, as described above. Also, channels arranged side by side on a surface of a flow plate may have different guide geometries.

Embodiments of the humidifier proposed here are shown in the figures and will be explained in more detail with reference to the following description. The figures are not to scale, in particular with regard to the ratios of widths, wavelengths and depths. The channel geometries are partly in the figures as embossed structures with constant wall thickness, partly as sprayed structures with massive intermediate areas or represented as their negatives. Irrespective of this, all channel geometries can be used for embossed metal plates as well as for injection molded plastic plates, although the wall thicknesses vary. It shows:

1 schematically an electrochemical system with a compressor, a humidifier and a fuel cell unit;

2 in perspective, the humidifier 1 with a variety of humidifier modules;

3a in perspective one of the humidifier modules 2 ;

3b the humidifier module off 3a in an exploded view;

3c another embodiment of the humidifier module 3a in an exploded view;

4 a sectional view of channels of a flow plate of the humidifier according to 3c wherein the sectional plane is oriented perpendicular to the plane plane of the flow plate;

5a in perspective, the channels 4 with guide geometries according to the invention in the form of protrusions on a bottom of the channels 4 ;

5b in perspective, one of the channels 4 with and without projections according to the invention, wherein in each case a resulting flow profile is shown;

6a in perspective, the channels 4 with guide geometries according to the invention in the form of sawtooth-shaped channel side walls;

6b a detail of one of the channels 6a in a plan view;

6c one of the channels 6a in perspective, once with and once without a resulting flow profile in the channel.

7a one of the channels 4 in a plan view with inventive guide geometries in the form of channel side walls with a relation to the channel bottom changing inclination;

7b -C cross sections of the canal 7a at different positions along the channel;

7d -E variations of the canal 7a in perspective view with and without a resulting flow profile;

8a C in perspective the channels 4 with guide geometries according to the invention in the form of a channel bottom shaft; such as

9a -B adjacent channels, which are separated by a corrugated web and in which dome-like elevations are arranged.

1 schematically shows an electrochemical system 1 with a compressor 2 , a humidifier 3 and a fuel cell unit 4 that z. B. has a plurality of hydrogen-oxygen fuel cells. From the compressor 2 gets the humidifier 3 via a first entrance 5 of the humidifier 3 a dry, to be humidified process gas fed, z. For example, molecular hydrogen or molecular oxygen. That in the humidifier 3 humidified process gas is then via a first output 6 of the humidifier 3 to the fuel cell unit 4 issued. There, the chemical energy of different process gases is converted by means of a plurality of membrane electrode units (MEA) into electrical energy. The in the reaction of the process gases in the fuel cell unit 4 resulting water vapor is the humidifier 3 via a second entrance 7 fed there and serves to moisten the dry process gas, the humidifier 3 over the first entrance 5 is supplied. The dehumidified water vapor is supplied via a second outlet 8th of the humidifier 3 z. B. delivered to the environment.

2 shows the humidifier 3 out 1 with a plurality of layered humidifier modules 9 between two end plates 10 and 11 layered and strained. Shown again are the inputs 5 and 7 as well as the outputs 6 and 8th at the end plate 10 of the humidifier 3 , Here and below, recurrent features are designated by the same reference numerals.

3a shows one of the humidifier modules 9 of the humidifier 3 , this in 3b is shown in an exploded view. The humidifier module 9 in 3b has a first flow plate 12 with a variety of channels 13 on. The humidifier module 9 also includes a second flow plate 14 , Between the first flow plate 12 and the second flow plate 14 is a water transfer medium 15 arranged in the form of a membrane. On this membrane are supported media on both sides 16a . 16b placed in the form of graphite fiber paper. Also on the water transfer medium side facing the second flow plate 14 are channels 17 by type of channels 3 the first flow plate 12 arranged in 3b however are covered. Not shown are beads and / or elastomer seals, which are the approximately rectangular areas of the flow plates 12 and 14 in which the channels 13 and 17 are arranged, gas-tight seal against the environment. The channels 13 and 17 are each at the water transfer medium 15 facing side of the flow plates 12 and 14 arranged. At the water transfer medium facing top of the channels 13 and 17 become the channels 13 and 17 in the present case in each case by the along the stacking direction (z-direction) 18 on both sides of the water transfer medium 15 arranged support media 16a . 16b limited.

The passage of gases in the stacking direction 18 via breakthroughs 19 in the flow plates 12 and 14 , The plane planes of the flow plates 12 and 14 are in 3b parallel to the x-axis 20 and the y-axis 21 aligned xy plane aligned. The x-axis 20 , the y-axis 21 and the z-axis 18 form a right-handed Cartesian coordinate system. In a stack with a variety of humidifier modules on the type of humidifier 9 make the breakthroughs 19 Lines for carrying dry gas, humidified gas, humid gas and dehumidified gas. The gases in those of the breakthroughs 19 formed lines become the channels 13 and 17 supplied or from the channels 13 and 17 dissipated, as in 3b indicated. For example, water vapor passes through the second input 7 into the channels 13 the first flow plate 12 , There, the water vapor partially releases its moisture via the water transfer medium 15 to that in the channels 17 the second flow plate 14 guided dry process gas. The partially dehumidified water vapor in the channels 13 will then go through the second exit 8th delivered to the environment. The dry process gas comes out of the compressor in the same way 2 over the entrance 5 into the channels 17 and takes it over the water transfer medium 15 Moisture in the channels 13 run on water vapor. The thus humidified process gas in the channels 17 will then go over the exit 6 the fuel cell unit 4 fed.

The individual flow plates or the humidifier modules of the humidifier 3 can be glued or potted together and / or connected by mechanical connection structures such as hooks or clips (not shown). At the flow plates 12 and 14 These are one-piece flow plates made of a non-corrosive metallic material into which the channels 13 and 17 each imprinted. The surfaces of the flow plates 12 and 14 are in the area of the channels 13 and 17 optionally hydrophilic or hydrophobic coated. The present structure is particularly easy to produce, because the individual flow plates are substantially identical in construction.

At the in 3b The embodiment shown, the channels 13 on the moist side of the water transfer medium 15 in the positive x-direction 20 flows through water vapor. In contrast, the channels 17 on the dry side of the water transfer medium 15 in the negative x-direction 20 flows through dry process gas. At the in 3b shown humidifier 3 it is thus a counterflow humidifier.

3c shows a modified embodiment of the humidifier 3 out 3b , The embodiment according to 3c differs from the embodiment according to 3b regarding the orientation of the channels 13 the first flow plate 12 and the channels 17 the second flow plate 14 relative to each other. Unlike in 3b are the channels 13 and the channels 17 or their main directions of extension or main flow directions in 3c arranged perpendicular or substantially perpendicular to each other. This is how the channels run 13 in 3c essentially parallel to the y-axis 21 while the channels 17 essentially parallel to the x-axis 20 are aligned. The channels 13 and 17 have in the 3b and 3c a length of about 30 cm.

The in the 3b and 3c shown embodiments also differ in the arrangement of the openings 19 in the flow plates 12 and 14 , The ones with the channels 13 in fluid communication breakthroughs 19 the first flow plate 12 are in 3c each at the top and bottom of the flow plate 12 arranged. They run parallel to the x-axis 20 , ie perpendicular to the main extension direction of the channels 13 , In contrast, those with the channels 17 in fluid communication breakthroughs 19 the second flow plate 14 in 3c each on the left and on the right edge of the flow plate 14 arranged. They run parallel to the y-axis 21 , so again perpendicular to the main direction of extension of the channels 17 ,

4 shows a section of two adjacent channels 13a and 13b the first flow plate 12 comparable 3c , 4 differs from 3c in that the flow plate 12 Here is made of a thermoplastic polymer material by injection compression molding. The cross sections of the channels 13a . 13b are in 4 hatched from top left to bottom right. The channels 13a . 13b become parallel to the plane plane of the flow plate 12 through a footbridge 27 separated from each other. The jetty 27 is between the channels 13a . 13b arranged and extends perpendicular to the plane plane of the flow plate 12 until the support medium 16a , The cutting plane 22 of the 4 is aligned parallel to the xz plane and in 3c shown schematically. The cutting plane 22 is thus perpendicular to the substantially parallel to the y-axis 21 extending main directions of extension of the channels 13a and 13b arranged. Likewise, the cutting plane 22 perpendicular to the plane plane of the flow plate 12 arranged, which is aligned parallel to the xy plane.

To the water transfer medium 15 towards and parallel to the plane plane of the flow plate 12 become the channels 13a . 13b on their tops 23a . 23b through between the first flow plate 12 and the water transfer medium 15 arranged support medium 16a limited. In the of the water transfer medium 15 remote negative z-direction 18 and parallel to the plane plane of the flow plate 12 become the channels 13a . 13b through channel bottoms 24a . 24b limited. Perpendicular or substantially perpendicular to the plane of the plane of the flow plate 12 become the channels 13a . 13b through channel side walls 25a . 26a respectively. 25b . 26b limited. The channel side walls 25a . 26a respectively. 25b . 26b close on both sides of the channel bottoms 24a . 24b to the channel bottoms 24a . 24b at. Here are the channel side walls 25a . 26a respectively. 25b . 26b opposite the canal floors 24a . 24b each slightly inclined to the outside. For example, close the channel bottom 24a and the channel side walls 25a . 26a in the cutting plane 22 Inclination angle β ₁ and β ₂ each of about 92 °.

The channels 13a . 13b have in the cutting plane 22 thus a substantially rectangular cross-section. One perpendicular to the plane plane of the flow plate 12 certain channel depth T of the channel 13a extends from the channel bottom 24a to the support medium 16a at the top 23a of the canal 13a , A channel width B determined parallel to the planar surface plane extends from the first channel side wall 25a of the canal 13a up to the second channel side wall 26a of the canal 13a , Here is the width B of the channel 13a about twice the depth T of the channel 13a , The channel depth T is z. B. between 0.2 mm and 4 mm, typically between 0.4 mm and 2 mm. The channel width B is z. B. between 0.5 mm and 5 mm, typically between 0.5 mm and 2 mm.

What up to here and below only as an example of the design of the channels 13a . 13b has been said or said can also for some or all other channels 13 the first flow plate 12 and / or for at least one of the channels 17 or for all of the channels 17 the second flow plate 14 be valid. In principle, channels of different embodiments can also be arranged on a surface of the same flow plate.

5a shows a specific embodiment of the channels 13a . 13b of the humidifier proposed here 3 , The channels 13a . 13b in this embodiment extend substantially straight in the positive y-direction 21 , Just for clarity, the channels 13a . 13b shown here as blocks, whereas the flow plate 12 into which the channels 13a . 13b are not explicitly shown. For example, the bridge is also 27 between the channels 13a . 13b not shown. In this sense, it is in the representation of the 5a a "negative".

In 5a corresponds to the orientation of the channels 13a . 13b relative to the other components of the humidifier module 9 essentially the in 3c shown. Of course, all embodiments shown here and below are the channels 13 and 17 according to 3c also according to an arrangement according to 3b , ie DC or countercurrent, transferable. For example, the channels become 13a . 13b at her (in 5a not shown) water transfer medium 15 facing tops 23a . 23b as in 4 through the support medium 16a limited. The example according to 5a differs from the according to 3c only by the fact that the channels 13 in 3c waving in the y direction 21 extend while the channels 13a . 13b in 5a a straight course in the y-direction 21 to have. However, the specific embodiments of the channels described here and hereinafter can be readily realized in both straight and wavy or otherwise curvilinear channels.

To the in 5a narrow hatched channel bottoms 24a . 24b show the channels 13a . 13b elongated projections 28a . 29a . 28b . 29b . 30b on, partly in the channels 13a . 13b protrude. In modified embodiments may alternatively or additionally also elongate recesses in the channel bottoms 24a . 24b be provided. Likewise, corresponding elongated projections and / or recesses may also be provided on the channel side walls 25a . 25b . 26a . 26b be provided. The proportion of protrusions 28a . 29a . 28b . 29b . 30b at one in the deepest level of the channels 13a . 13b Projected area of the channel floor here is about 12 percent.

The elongated projections 28a . 29a . 28b . 29b . 30b are relative to the main direction of extension of the channels 13a . 13b arranged at an angle. In particular, the elongated projections 28a . 29a . 28b . 29b . 30b in 5a so relative to the y-direction 21 arranged at an angle. This comes z. B. thereby expressed that the elongated projections 28a . 29a . 28b . 29b . 30b with in 5a dashed lines shown centerlines 31a . 31b the channel floors 24a . 24b each include an angle α of about 50 °. The midline 31a connects z. B. along the Main extension direction of the channel 31a all those points of the channel floor 24a leading to the canal floor 24a adjacent side walls 25a . 26a each have the same distance. The midline 31b can be defined in an analogous way. The elongated projections 28a . 29a in the canal 13a and the elongated projections 28b . 29b . 30b in the canal 13b are each aligned parallel or substantially parallel to each other. Along the main extension direction of the respective channel 13a . 13b successive projections are arranged such that their mutually facing ends parallel to the channel cross-section, in 5a ie in particular along the x-direction 20 are spaced apart or at least do not overlap.

The channels 13a . 13b each have a plurality of such projections along their main extension direction. The length of a single one of the protrusions 28a . 29a . 28b . 29b . 30b is roughly equivalent to in 4 shown channel width B. Along the main extension direction of the channels 13a . 13b are the tabs 28a . 29a . 28b . 29b . 30b arranged at regular intervals from each other. A not separately highlighted here perpendicular to the plane plane of the flow plate 12 certain height h of the projections 28a . 29a . 28b . 29b . 30b here is about 15 percent of in 4 shown channel depth T. The projections 28a . 29a . 28b . 29b . 30b so they protrude perpendicular to the plane plane of the flow plate 12 by about 15 percent of the channel depth T from the channel bottom 24a . 24b in the channel 13a . 13b into it. Along their longitudinal direction, the projections 28a . 29a . 28b . 29b . 30b in each case a constant maximum height h in a constant triangular profile. A perpendicular to the longitudinal direction of the projections 28a . 29a . 28b . 29b . 30b certain cross-sectional area of the projections 28a . 29a . 28b . 29b . 30b is in 5a each about 4 percent of the cross section A of the respective channel. The cross section A of the channels 13a . 13b is given approximately by A = T · B ( 4 ). Through the projections 28a . 29a . 28b . 29b . 30b Both the cross-section A of the channels 13a . 13b and the corresponding channel depths along the main direction of extension of the channels 13a . 13b changed.

The projections 28a . 29a . 28b . 29b . 30b in the channels 13a . 13b represent Leitgeometrien, each one perpendicular to the plane plane of the flow plate 12 acting disturbance one along the main extension direction of the channels 13a . 13b through the channels 13a . 13b flowing ideally linear laminar gas flow cause. For example, the projections 28a . 29a . 28b . 29b . 30b due to their arrangement, one in the positive y-direction 21 through the channels 13a . 13b flowing gas flow along the main direction of extension of the channels 13a . 13b each impose a roughly spiral flow profile. This is in 5a through arrows 42a . 42b indicated with respect to channel centerlines 40a . 40b each have the same direction of rotation. Only for better representation of the course of the channel centerlines 40a . 40b are additional points 41a . 41b shown in which the channel centerlines 40a . 40b intersect each of the channel cross-sectional areas hatched from bottom left to top right. As a result, the gas exchange and thus the moisture flow within the channels 13a . 13b perpendicular to the plane plane of the flow plate 12 decisively improved. As explained above, this leads to an increase in the water transfer between the water vapor-carrying channels 13 the first flow plate 12 and the dry process gas leading channels 17 the second flow plate 14 over the water transfer medium 15 ( 3a . 3b ).

5b shows a modified embodiment of the channel 13b the flow plate 12 out 5a , Shown is in each case a part of the flow plate 12 into the canal 13b is impressed. In contrast to the representation according to 5a is it in the representation according to 5b So a "positive" representation of the channel. Top in 5b is a section 40 of the canal 13b shown in which no protrusions according to the invention are arranged, so that an ideal linear laminar flow results, represented here by straight and parallel flow lines 42 , Down in 5b is a section 41 of the canal 13b shown in which a projection according to the invention 28b on the canal floor 24b is arranged so that along the z-direction 18 , ie perpendicular to the plane plane of the flow plate 12 , a disturbance of the ideal linear laminar flow results. The resulting, along the main extension direction of the channel 13b spirally winding flow profile is through corresponding flow lines 43 shown. It becomes clear that the ideally linear laminar flow is disturbed, but not to the extent that a turbulent flow would result. In particular, the disturbance of the stratification can be recognized, while no whirls are recognizable.

6a shows a further embodiment of the channels 13a . 13b the first flow plate 12 in perspective view. As in 5a are the channels 13a . 13b in 6a represented as blocks and thus as "negative". The relative arrangement of the channels 13a . 13b in 6a to the other components of the humidifier module 9 again exemplifies that of the 3c , Also in 6a is the plane plane of the flow plate 12 aligned parallel to the xy plane. The hatched cross-sections shown are parallel to the xz plane and thus perpendicular to the plane of the plane of the flow plate 12 , Again not explicitly shown is the flow plate 12 itself, in which the channels 13a . 13b are formed. For clarity, also not shown are the bridge 27 between the channels 13a . 13b and the support medium 16a that the channels 13a . 13b limited in the positive z-direction. The following is an example of the structure of the channel 13b in 6a described. The channel 13a points in 6a the same structure as the channel 13b ,

The channel side walls 25b . 26b of the canal 13b are also in 6a substantially parallel to the yz-plane and thus substantially perpendicular to the plane plane of the flow plate 12 aligned. Parallel to the xy plane and thus parallel to the planar surface plane of the flow plate 12 have the channel side walls 25b . 26b a sawtooth profile. The channel side walls 25b . 26b thus point along the main extension direction of the channel 13b , here along the y-direction 21 , a plurality of edges K1, K2, K3, K4, etc., and L1, L2, L3, L4, etc., at which the cross-section A of the channel 13b changes abruptly. The edges are K1, K2, K3, K4, etc. of the first channel side wall 25b the edges L1, L2, L3, L4, etc. of the second channel sidewall 26b opposite each other. This will change the cross section A of the channel 13b at the corresponding position along the main direction of extension of the channel 13b even stronger. The edges K1, K2, K3, K4, L1, L2, L3, L4, etc. are along the main extension direction of the channel 13b arranged at regular intervals. Here, the distance between two successive edges of the same channel side wall is in each case approximately 1.5 · B _max , where B _max is parallel to the plane of the plane of the flow plate 12 certain maximum width of the channel 13b is.

Between each two consecutive edges are channel sections M1, M2, M3, etc., which are each formed the same. The sawtooth profiles of the channel side walls 25b . 26b thus point along the main extension direction of the channel 13b each have a periodic structure. The wavelength λ _{S of} this periodic structure is here z. B. λ _S = 10 · B _max , where B _max is parallel to the plane plane of the flow plate 12 certain maximum width of the channel 13b is. The channel sections M1, M2, M3, etc. merge into one another at the edges. For example, the channel sections M1 and M2 merge into one another at the opposite edges K2 and L2. In the channel sections M1, M2, M3, the cross section A of the channel decreases 13b each in the positive y-direction 21 , At the edges takes the cross section A of the channel 13b in the positive y-direction 21 so abruptly too.

The configuration of the edges between the channel sections M1, M2, M3, etc. is in 6b shown schematically. 6b shows a plan view of the channel 13b out 6a , especially on the canal 13b in the region of the edges K2 and L2 between the channel sections M1 and M2. The remaining edges of the channel 13b are formed in the same way.

It can be clearly seen how the plane perpendicular to the plane plane of the flow plate 12 certain cross section A of the channel 13b is reduced in the section M1 in the positive y-direction until it assumes a minimum value arm in the region of the edges K2, L2. The edges K2, L2 are formed blunt. At the edges K2, L2 form the channel side walls 25b . 26b in the xy plane and thus parallel to the plane plane of the flow plate 12 So in each case an angle γ, which is slightly larger than 90 °, here z. B. about 95 °. Starting from the plane of the minimum cross section A _min , the cross section A of the channel increases 13b then in the positive y-direction 21 until it assumes a maximum value A _max . For A _min and A _{max the} following applies: (A _max - A _min ) / A _min = 0.9. The along the main extension direction of the channel 13b certain maximum distance d, within which the cross-section A in the region of the edge K2, L2 increases from its smallest value A _min to its maximum value A _max , is less than 0.1 · λ _S , where λ _S is defined as described above should be. It is therefore: d ≤ 0.1 · λ _S. Starting from A _max , the cross-section A in the channel section M2 then returns in the positive y-direction 21 from etc.

Due to the abrupt change in the cross section A in the region of the edges K1, L1, K2, L2, etc., in the region of the edges in each case again arise perpendicular to the plane plane of the flow plate 12 acting disturbances of the ideally linear laminar flow in the channel 13b flowing gas. The edges between the channel sections M1, M2, M3, etc. thus again form guide geometries in the channel 13b , in particular perpendicular to the plane plane of the flow plate 12 , in 6b ie in particular perpendicular to the plane of the drawing, in each case disturbances of the ideally linear laminar flow in the channel 13b effect guided gas flow. As described above, the water transfer rate of the humidifier 3 significantly improved.

6c shows a perspective view of the channel 13b out 6a , in contrast to the representation of 6a again in a "positive" representation, ie as an impression in the flow plate 12 (see. 5b ). In the upper part of the figure is the channel 13b without a gas flowing therein. In the lower part of the figure are flow lines 44 one in the channel 13b flowing gas illustrates. At the wave-like course of the streamlines 44 is the disorder of the ideally linear laminar flow perpendicular to the plane plane of the flow plate 12 recognizable. This disorder is here by the edges K1, K2, K3, K4, L1, L2, L3, L4, etc., and by the intervening channel sections M1, M2, M3, etc. in the positive y-direction 21 each reducing cross section causes.

7a C show another embodiment of the channel 13b the first flow plate 12 , The relative arrangement of the channel 13b in the 7a -C to the other components of the humidifier module 9 corresponds again exemplified that of 3c , These are just examples of the channel 13b Of course, the embodiment shown is also on the other of the channels 13 the first flow plate 12 and / or on the channels 17 the second flow plate 14 transferable. 7a shows a plan view of the channel 13b , the line of sight is in 7a So the negative z-direction 18 , The 7b and 7c show cross sections of the canal 13b out 7a perpendicular to the plane plane of the flow plate 12 , The is in each case based on the in the 7a -C shown coordinate systems clearly. The cutting planes or image planes of the 7b and 7c are in 7a highlighted by dashed lines AA and BB.

The basis of the 7a C illustrated embodiment is characterized in that inclination angles β ₁ and β ₂ , which are the channel side walls 25b and 26b each with the channel bottom 24b along the main direction of extension of the channel 13b to change. Here they change in particular continuously. In the plan view of 7a are the changes of the channel sidewalls 25b and 26b hatched shown. The fact that the inclination angles β ₁ and β _{2 of} the channel side walls 25b . 26b relative to the channel bottom 24b along the main extension direction of the channel 13b , here in the positive y-direction 21 , continuously change, comes in 7a characterized in that the upper ends 32b . 33b the channel side walls 25b . 26b that is the water exchange medium 15 facing, parallel to the plane plane of the flow plate 12 , so parallel to the xy plane, wavy or sinusoidal.

7b shows a cross section of the channel 13b out 7a along a plane AA, which is perpendicular to the plane plane of the flow plate 12 is aligned. In level AA, the first channel sidewall closes 25b with the channel bottom 24b a first inclination angle β ₁ of about 90 °. In contrast, the second channel side wall closes 26b with the channel bottom 24b in the same plane AA a second inclination angle β ₂ of about 105 °.

7c shows a cross section of the channel 13b out 7a along another plane BB, which is perpendicular to the plane plane of the flow plate 12 is aligned. In level BB, the first channel sidewall closes 25b with the channel bottom 24b a first inclination angle β ₁ of about 105 °. In contrast, the second channel side wall closes 26b with the channel bottom 24b in the same plane BB a second inclination angle β ₂ of about 90 °.

Of course, it is also conceivable that the inclination angle β ₁ and / or β ₂ does not change or not only continuously, as in the 7a -C, but also discontinuously. In this way, edge-like structures are created on the channel side walls. It is also conceivable that in a given section of the channel 13b only one of the inclination angles β ₁ , β ₂ changes or both inclination angles β ₁ , β ₂ change to different degrees, which then changes with a change in the cross section A of the channel 13b accompanied.

The inclination angles β ₁ and / or β ₂ change along the main extension direction of the channel 13b typically such that the cross section A of the channel 13b remains constant or remains almost constant. This means that the inclination angle β ₁ along the main extension direction of the channel 13b increases when the inclination angle β ₂ in the same section of the channel 13b and in the same direction along the main direction of extension of the channel 13b decreases and vice versa. Preferably, the angles of inclination β ₁ and / or β ₂ in modified embodiments each change such that the cross-section A of the channel 13b along the main extension direction of the channel 13b varies by a maximum of 60 percent, preferably at most 30 percent, preferably at least 5 percent, more preferably at least 10 percent.

The in the 7a -C described change in the slope of the channel side walls 25b . 26b relative to the channel bottom 24b steers that in the channel 13b flowing gas typically both parallel and perpendicular to the plane surface plane of the flow plate 12 from. This causes in particular perpendicular to the plane plane of the flow plate 12 the desired disturbance of the ideally linear laminar flow of the gas in the channel 13b with the described advantageous effects on the water transfer rate between the channels 13 and 17 on both sides of the water transfer medium 15 ,

The 7d and 7e show perspective views of modified embodiments of the channel 13b from the 7a -C, again in a "positive" representation, ie as an impression in the flow plate 12 , Shown are each cross sections 50 . 51 . 52 ( 7d ) respectively. 53 . 54 ( 7e ) of the channel 13b at different positions along the main direction of extension of the channel 13b , It can be seen that the inclination angle β ₁ , β _{2 of} the channel side walls 25b . 26b relative to the channel bottom 24b along the main extension direction of the channel 13b to change. The result effected, along the z-direction 18 aligned disturbance of the ideally linear laminar flow in the channel 13b is at the wavy course of the corresponding flow lines 45 ( 7d ) respectively. 46 ( 7e ) to recognize.

Further embodiments of the channels 13a . 13b are in the 8a -C described. Of course, these embodiments are also readily applicable to the rest of the channels 13 the first flow plate 12 and / or on the channels 17 the second flow plate 14 transferable. The relative arrangement of the channels 13a . 13b in the 8a -C to the other components of the humidifier module 9 corresponds again exemplarily that of the 3c , As before, the channels 13a . 13b for the sake of clarity, are shown as blocks. Not shown, however, is the flow plate 12 into which the channels 13a . 13b are impressed. In particular, the bridge is 27 between the channels 13a . 13b Not shown.

The in the 8a C shown embodiments of the channels 13a . 13b are characterized by a along the main extension direction of the channels 13a . 13b changing channel depth T off. The main extension direction of the channels 13a . 13b runs in the 8a -C again parallel to the y-axis 21 , The channel depth T becomes perpendicular to the plane plane of the flow plate 12 certainly, in the 8a In each case along the z-direction 18 , The channel depth T extends z. B. from the channel bottom 24a . 24b to the support medium 16a that the channels 13a . 13b to the water transfer medium 15 limited. In the embodiments according to the 8a -C is a difference between one along the main direction of extension of the channels 13a . 13b certain minimum channel depth T _min and one along the main direction of extension of the channels 13a . 13b certain maximum channel depth T _{max in} each case between 10 and 25 percent of the maximum channel depth. The following applies: 0.1 · T _max ≤ T _max - T _min ≤ 0.25 · T _max .

In the examples of 8a -C is the modulation of the channel depth T of the channels 13a . 13b along the main extension direction of the channels 13a . 13b each periodically with a period length λ _T. For the period length λ _{T, the} following applies: 10 × B ≦ λ _T ≦ 15 × B, where B is one parallel to the plane plane of the flow plate 12 certain width of the respective channel 13a . 13b is. In 8a the modulation of the channel depth T z occurs. B. approximately sinusoidal. The channel bottoms 24a . 24b So there each have a wave-like course.

Of course, the modulation of the channel depth does not have to be periodic or continuous, as in the 8a -C shown. It is also conceivable that the change of the channel depth along the main extension direction of the channels 13a . 13b at least partially discontinuous, z. B. in stages. Also, the channel bottom 24a and or 24b perpendicular to the plane plane of the flow plate 12 have a sawtooth profile, for example in the manner of the side walls 25b or 26b according to the 6a . 6b ,

A modulation of the channel depth T according to 8a -C causes a direct directed to plane of the plane disturbance in the channels 13a . 13b guided ideally linear laminar flow.

In the in 8c shown embodiment, the two adjacent channels 13a . 13b in each case a modulation of the channel depth T with the same period length λ _T. Here are the immediately adjacent and parallel to each other channels 13a . 13b However, arranged along their main extension direction such that the periods of their respective channel depth modulation are shifted by a half period length λ _T / 2 against each other. In perpendicular to the plane plane of the flow plate 12 aligned levels is thus a wave crest of the channel bottom wave of the channel 13a each a trough of the channel bottom shaft of the channel 13b immediately adjacent and vice versa. This causes an exchange and / or a partial mixing of the adjacent channels 13a . 13b guided gas flows, whereby the exchange over the web 27 and the gas-permeable support medium 16a he follows. The perpendicular to the plane plane of the flow plate 12 Directed interference from in the channels 13a . 13b guided ideal linear laminar gas flows is carried out in a particularly effective manner.

9a and 9b show further embodiments of the channels 13a . 13b the flow plate 12 , The channels 13a . 13b are doing transversely to their main extension direction, in the 9a and 9b ie along the x-direction 20 , by footbridges 55 . 27 . 56 limited. The jetty 27 is between the immediately adjacent channels 13a . 13b arranged and separates them from each other. The bridges 55 . 27 form sidewalls 25a . 25b of the canal 13a , The bridges 27 . 56 form sidewalls 25b . 26b of the canal 13b , The bridges 55 . 56 extend straight along the main extension directions of the parallel channels 13a . 13b , The one between the straight bars 55 . 56 arranged bridge 27 In contrast, it extends in a wave-like manner along the main directions of extension of the channels 13a . 13b , In particular, the jetty has 27 a periodic waveform. A wavelength λ _{W of} the wave-like structure of the ridge 27 is slightly less than twice the maximum width B _{max of} the channels 13a . 13b perpendicular to the main direction of extension of the channels 13a . 13b is determined.

On the canal floors 24a . 24b are dome-like structures 60 arranged partially in the channels 13a . 13b protrude, in particular, a height of 20-50% of the height of the webs 55 . 56 , respectively. 27 exhibit. Likewise protrudes another dome-like structure 61 from the channel side wall 25a of the canal 13a in 9a in the channel 13a It also has a lower height than the bridge 55 on, like the edge 70 is clarified. Comparable dome-like structures projecting from the channel wall are shown in FIG 9b given. Like the wavy bridge 27 so do the dome-like elevations 60 . 61 perpendicular to the plane plane of the flow plate 12 on whose surface are the channels 13a . 13b disturbances of an ideally linear laminar flow flowing in these channels. The dome-like elevations 60 . 61 may have in plan view round or polygonal-rounded shapes, as in the channel 13a of the 9a is shown.

Along the main extension direction of the canal 13b of the 9a are the dome-like elevations 60 , for example arranged approximately equally spaced. In flow direction - in 9 should this be the positive y-direction 21 be - are these dome-like elevations 60 , in channel 13b of the 9a all shortly after the areas of the channel where it has a local maximum cross-section. The dome-like elevations 60 in channel 13b of the 9a are with respect to perpendicular to the main direction of extension of the channel 13b certain cross section all arranged approximately centrally.

9b illustrates that even several dome-like surveys can work together, which at the same height in the main extension direction of the channels 13a . 13b may be arranged or offset from each other. It can be a whole group of smaller domed surveys or a pair of domed surveys. The dome-like elevations can protrude from the channel bottom or projecting from the channel wall sections, ie in particular with respect to the web reduced height.

Depending on the configuration of the wave-like course of the web 27 and the arrangement of the dome-like elevations 60 . 61 can be a different disorder of the ideal linear laminar flow in the channels 13a . 13b perpendicular to the plane plane of the flow plate 12 be achieved. On the one hand, this can be done in the channel 13a flowing gas partly over the bridge 27 in the channel 13b be pushed and vice versa, so it's between the channels 13a . 13b comes to a gas exchange. This takes place via the gas-permeable support medium 16a (please refer 3c ), which is between the flow plate 12 and the water transfer medium 15 is arranged, if necessary, this can be facilitated by a non-constant course of the height of one or more webs. On the other hand, in the channels 13a . 13b flowing gas are imparted so that it comes within a channel to a gas exchange. In both cases, as well as in mixed mechanisms, there is a change in the moisture gradient across the height profile of a channel.

Claims (21)

Humidifier ( 3 ), in particular for humidifying process gas for fuel cells, comprising: - a first input ( 5 ) for supplying dry gas and a first output ( 6 ) for dispensing humidified gas, - a second input ( 7 ) for supplying moist gas and a second outlet ( 8th ) for discharging dehumidified gas, - at least a first ( 12 ) and a second ( 14 ) Flow plate, - one between the first ( 12 ) and the second flow plate ( 14 ) arranged water transfer medium ( 15 ) which is gas impermeable or substantially gas impermeable during operation, the first ( 12 ) and the second flow plate ( 14 ) each channels ( 13 . 17 ) for guiding the gas, characterized in that the channels ( 13 . 17 ) along their main extension direction each having a plurality of Leitgeometrien which are formed such that they are perpendicular to the plane plane of the respective flow plate ( 12 . 14 ) cause a disturbance of the ideally linear laminar flow of the gas carried in the channel. Humidifier ( 3 ) according to claim 1, characterized in that the guide geometries formed in the channel walls elongated recesses and / or arranged on the channel walls and projecting into the channel elongated projections ( 28a . 29a . 28b . 29b . 30b ) extending along the main direction of extension of the channel ( 13a . 13b ) extending center line ( 31a . 31b ) of the respective channel wall include an acute angle α, wherein preferably: 45 degrees ≤ α ≤ 70 degrees (angular dimension). Humidifier ( 3 ) according to claim 2, characterized in that a cross-sectional area of the recesses , which is perpendicular to the length of the recesses, is in each case between 2 and 12 percent, preferably between 2 and 10 percent, of the minimum cross-section (A _min ) of the channel (A). 13a . 13b ) and / or that one perpendicular to the length of the projections ( 28a . 29a . 28b . 29b . 30b ) certain cross-sectional area of the projections ( 28a . 29a . 28b . 29b . 30b ) each between 2 and 12 percent, preferably between 2 and 10 percent of maximum cross section (A _max ) of the channel ( 13a . 13b ) is. Humidifier ( 3 ) according to one of claims 2 or 3, characterized in that along the main extension direction of the channel ( 13a . 13b ) immediately successive recesses and / or protrusions ( 28a . 29a . 28b . 29b . 30b ) are arranged such that their mutually facing ends parallel to the cross section of the channel ( 13a . 13b ) are spaced. Humidifier ( 3 ) according to one of the preceding claims, characterized in that the guide geometries along the main extension direction of the channel ( 13b ) extending and merging channel sections (M1, M2, M3) of the channel ( 13b ), wherein a cross section (A) of the channel decreases along the channel sections (M1, M2, M3) in each case in the same direction and wherein the transition between two of the merging channel sections (M1, M2, M3) in each case via a blunt edge ( K1, K2, K3, K4, L1, L2, L3, L4), at which the cross-section of the channel ( 13b ) changes. Humidifier ( 3 ) according to claim 5, characterized in that for the change of the cross-section (A) of the channel ( 13b ) at the blunt edge (K2, L2) between two of the merging channel sections (M1, M2) with respect to the smallest section A _min and the largest section A _max in the region of the edge (K2, L2): (A _max - A _min ) / A _min ≦ 1, preferably 0.75 ≦ (A _max -A _min ) / A _min ≦ 1, particularly preferably 0.8 ≦ (A _max -A _min ) / A _min ≦ 1. Humidifier ( 3 ) according to one of claims 5 or 6, characterized in that the channel sections (M1, M2, M3) of the channel ( 13b ) at least partially through at least one channel side wall ( 25b . 26b ) of the channel, which are parallel to the plane plane of the respective flow plate ( 12 ) has a sawtooth-like profile, preferably by two mutually opposite channel side walls ( 25b . 26b ) of the type mentioned, and / or that the channel sections (M1, M2, M3) of the channel ( 13b ) at least partially through at least one channel bottom ( 24b ) of the channel ( 13b ) formed perpendicular to the plane plane of the respective flow plate ( 12 ) has a sawtooth-like profile, wherein the edges (K1, K2, K3, K4, L1, L2, L3, L4) between the merging channel sections (M1, M2, M3) by the edges of the sawtooth-like profile of the channel side walls ( 25b . 26b ) and / or the channel bottom are given. Humidifier ( 3 ) according to claim 7, characterized in that the sawtooth-like profile along the main extension direction of the channel ( 13b ) is periodic, wherein for a period length λ _{S of} the sawtooth-like profile and a width B of a maximum cross-sectional area of the channel ( 13b ) preferably: 5 * B ≦ λ _S ≦ 20 * B, more preferably 10 * B ≦ λ _S ≦ 15 * B. Humidifier ( 3 ) according to one of the preceding claims, characterized in that an angle β, which a channel bottom ( 24b ) of the channel ( 13b ) with a to the channel bottom ( 24b ) adjoining channel side wall ( 25b . 26b ) of the channel ( 13b ), at least in sections changes along the main extension direction of the channel bottom, wherein preferably: 90 ° ≤ β ≤ 120 ° (angular dimension). Humidifier ( 3 ) according to claim 9, characterized in that the angle β changes at least in sections continuously. Humidifier ( 3 ) according to one of claims 9 or 10, characterized in that the angle β changes discontinuously at least once. Humidifier ( 3 ) according to one of claims 9 to 11, characterized in that the channel bottom ( 24b ) with a to the channel bottom ( 24b ) adjoining first channel side wall ( 25b ) encloses an angle β ₁ and with a to the channel bottom ( 24b ) and the first channel side wall ( 25b ) opposite second channel side wall ( 26b ) includes an angle β ₂ , wherein the angles β ₁ and β _{2 are} respectively determined in the same plane and wherein the angles β ₁ and β ₂ along the main extension direction of the channel ( 13b ) at least in sections such that the cross-section (A) of the channel in this section changes by less than 60 percent, preferably by less than 30 percent. Humidifier ( 3 ) according to one of the preceding claims, characterized in that the channel ( 13b ) along the main extension direction of the channel ( 13b ) has at least sections a constant channel depth (T), wherein the channel depth (T) perpendicular to the plane plane of the respective flow plate ( 12 ) is determined. Humidifier ( 3 ) according to one of the preceding claims, characterized in that the channel ( 13a . 13b ) has along the main extension direction of the channel at least partially changing channel depth (T). Humidifier ( 3 ) according to claim 14, characterized in that the difference between a maximum channel depth and a minimum channel depth of the same channel ( 13a . 13b ) is less than 40 percent of the maximum channel depth, preferably between 10 and 25 percent of the maximum channel depth. Humidifier ( 3 ) according to one of claims 14 or 15, characterized in that the channel depth (T) along the main extension direction of the channel ( 13a . 13b ) Periodically changes at least in sections, preferably continuously. Humidifier ( 3 ) according to claim 16, characterized in that for the period length λ _{T of} the change of the channel depth and a width B of a perpendicular to the main extension direction of the channel ( 13a . 13b ) certain cross-sectional area of the channel ( 13a . 13b ): 5 * B ≦ λ _T ≦ 20 * B, preferably 10 * B ≦ λ _T ≦ 15 * B. Humidifier ( 3 ) with two in the same flow plate ( 12 ) adjacent, mutually parallel channels ( 13a . 13b ), each according to claim 17, wherein the adjacent channels ( 13a . 13b ) have different period lengths or where the adjacent channels ( 13a . 13b ) have the same period length λ _T and the periods of the adjacent channels ( 13a . 13b ) along the main extension direction of the channels ( 13a . 13b ) are shifted relative to one another, preferably by a length Δλ _T , for which the following applies: λ _T / 3 ≦ Δλ _T ≦ 2 · λ _T / 3, particularly preferably around Δλ _T = λ _T / 2. Humidifier ( 3 ) according to one of the preceding claims, characterized in that at least one of the flow plates straight running webs ( 55 . 56 ) and corrugated webs ( 27 ), which channels ( 13a . 13b ) limit transversely to the main direction of extension. Humidifier ( 3 ) according to claim 19, characterized in that the straight webs ( 55 . 56 ) and the corrugated webs ( 27 ) are arranged alternately. Humidifier ( 3 ) according to one of the preceding claims, characterized in that on the channel bottom ( 24a . 24b ) of the channels ( 13a . 13b ) dome-like surveys ( 60 . 61 ) are arranged.

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