DE102007048321A1 - Apparatus and method for separating a liquid from a gas stream and fuel cell system - Google Patents

Abstract

The invention relates to a device for separating a liquid from a gas stream, having a flow channel (1) which has a first subelement (2) and a second subelement (3) in the flow direction (P) of the gas stream, which at least partially has a larger internal dimension ( d2) as the first subelement (2), wherein a transition (8b) of the inner sides (6, 12, 7) between the second subelement (3) and a third subelement adjoining the second subelement (3) in the flow direction (P) (4) of the flow channel (1) is stepped and formed the second sub-element (3) is widening. The invention also relates to a method for separating e flowing gas stream.

Description

The The invention relates to an apparatus and a method for depositing a liquid from a gas stream, with a flow channel, which in the flow direction of the gas flow a first and a second sub-element, which at least partially a larger internal dimension than the first sub-element has, and a transition between the second and a third sub-element is stepped. Furthermore it concerns the invention a fuel cell system with such a device and a method for separating a liquid a gas stream flowing in a flow channel.

In Fuel cell systems occur in specific operating conditions in that water penetrates into the fuel cell stack, wherein this on both the cathode side and on the anode side of a Fuel cell is given. Cause this can both condensed water, as well as water from the fuel cell, which was recirculated. Especially with load jumps It happens that water accumulations of components or Loosen pipes and get carried away. These then land in the fuel cell stack and can lead to a functional impairment lead in a fuel cell or a negative impact in the Restart or even when starting in cold conditions, especially near or below the 0 degree limit.

in principle However, such a problem can also be independent from a fuel cell system to all other systems, in which as a gas stream, a two-phase mixture with liquid and gas being transported.

at Conventional separator equipment is common provided that a wire mesh or a mesh or a cyclone is used to improve fluid separation to be able to reach by taking larger drops be formed. A disadvantage of these designs is therein to see that an unwanted extra Pressure loss and an additional necessary volume required is, especially if this device in a fuel cell system is provided.

From the DE 101 20 018 A1 a fuel cell system with a water separator is known, which has an inlet tube in a first embodiment, which is arranged perpendicular to a manifold and opens into this. The water-laden stream is introduced via the inlet pipe. By this vertical arrangement of these two pipes to each other, the water-laden stream flowing into the collecting pipe is swirled along the inside of the collecting pipe, wherein the water in the stream is thrown by centrifugal force to the wall of the collecting pipe. At the same end, where the inlet pipe opens into the manifold, a curved exhaust pipe is inserted into the manifold, wherein the axis of the exhaust pipe in the junction region also extends perpendicular to the axis of the manifold. The exhaust pipe is tapered at the end located in the manifold. Furthermore, this water separator has a sump for collecting the separated water, which sump is formed separately and independently of the inlet pipe and the exhaust pipe at the opposite end of the collecting pipe. The sump is thus formed without operative connection with the exhaust pipe and the inlet pipe. In a further embodiment, a water separator is formed, in which, in the flow direction of the gas stream, first the collecting pipe is arranged, at the end of which the partially tapered exhaust pipe is introduced. In this embodiment, the exhaust pipe and the manifold along the longitudinal axis are arranged one behind the other, wherein it is essential that the manifold at the end at which the exhaust pipe extends into the manifold, is open and thus the gas stream and water droplets can escape there and in a perforated cylinder or screen can take the form of a wire mesh to be collected there. From this cylinder or screen then dripping the water into a sump below.

In addition, from the DE 10 2004 022 245 A1 a moisture exchange module for a fuel cell system is known, which is designed for humidification of the cathode space of a fuel cell supplied oxidant. In addition to this functionality, the moisture exchange module is also designed with means for separating liquid from the gas stream leaving the fuel cell. For this purpose, a groove formed on the inside is realized in a housing of the moisture exchange module, so that two partial regions with different inner diameters are formed in the housing. The groove is arranged in a region in which the gas flow flows due to its swirl movement along the housing of the inflow region, so that liquid droplets located in the gas flow collect in the region of the housing due to the centrifugal force in which the groove is arranged. From the region of the groove, the collecting liquid can then be removed from the inflow region via a valve or a gutter. The extension of the cross section may be stepped or continuously formed. However, the groove is formed in each case in cross section as a stepped increase in diameter.

It Object of the present invention, an apparatus and a To provide a method, with which or at which the liquid separation can be improved. Especially when used in a Fuel cell system intended this liquid separation from a gas stream without large pressure loss and with minimized Space can be made.

These The object is achieved by a device having the features as claimed 1, and a method comprising the features of claim 13 has dissolved. In addition, the task gets through a fuel cell system having the features of claim 12 has dissolved.

A Device according to the invention for depositing a Liquid from a gas stream comprises a flow channel, which in the flow direction of the gas flow a first and having a second sub-element. The second subelement is like this trained that it at least partially a larger Internal dimension than the first sub-element has. A transition the inner sides between the second sub-element and one to the second sub-element in the flow direction subsequent third sub-element of the flow channel is stepped. The second subelement is on its inside in the longitudinal direction considered formed at least partially expanded. By This embodiment of the flow channel can be improved Ensuring liquid separation, wherein the device can be configured space-minimized. The unwanted liquid, especially water, in the gas stream moves above all along the insides the sub-elements and thus in particular on the walls of the tubes. Liquid drop in the gas flow itself is minimal in comparison on.

Therefore It is also in the device according to the invention no longer necessary to use a separator principle, which the liquid drops first brings to connect to larger drops, to then merge them, as for example in Wire knit separators with the appropriate meshes the case is.

One Such wire mesh is thus particularly in the inventive Device no longer provided.

Much more can by the specific arrangement of the sub-elements of the flow channel and the inside design by the gradual training between the second and the third sub-element quasi a kind Chamber are created, in which the located in the gas stream Can collect liquid. In particular, this makes it special effectively the liquid fraction moving along the insides effectively separated and collected.

The second sub-element is particularly in the direction of the third sub-element formed expanded. Under an expansion is a with Viewing along the longitudinal axis of increasing internal dimensions understood. In particular, the widening can thus also be funnel-shaped or be cone-shaped.

Preferably the second subelement is continuously widening on its inside educated. In particular, it is thus in the direction of the third sub-element initially a continuous and therefore not graded Expansion of the second part element formed, which, however, then is stepped again at the transition to the third sub-element and thus at this transition from the second to the third subelement in particular, a cross-sectional reduction is realized.

Preferably has the second sub-element at its end adjacent to the third sub-element the largest inside dimension. Precisely because of this at the transition between the second and the third subelement form relatively large collection areas, which also relatively A lot of fluid can be accumulated without them is entrained again with the gas stream and through the third sub-element through.

Preferably corresponds to the internal dimension of the third sub-element at the transition to the second subelement the inner dimension of the first subelement at the transition to the second subelement. At both ends of the second sub-element then opens into further sub-elements, which thus essentially have the same internal dimensions.

Preferably has the opening to the third sub-element rear wall of the second sub-element a substantially vertically formed Inside up. Also, this can be achieved by a relatively short design a compact and space-minimized design can be achieved and moreover through the very abrupt transition prevents the entrainment of already collected water become. However, the inside of the back wall can also be opposite the vertical be at least partially inclined.

The end of the third subelement facing the second subelement preferably extends into the interior of the second subelement. By such a configuration, a collecting area for the separated liquid at the transition between the second and the third sub-element created in a particularly preferred manner the. The end of the third sub-element located in the second sub-element thus serves as a kind of bottom or cover for the collecting region and entrainment of the liquid in the direction of the third sub-element and further can thereby be prevented particularly effectively. In addition, a very low pressure loss can be achieved by this configuration.

Preferably The end of the third subelement extends into the interior in this way the expanded portion of the second subelement that intervenes the outside of the third part element and the inside of the second sub-element, an air space is formed, in which collectable from the gas stream liquid can be collected is. The flow channel is thus virtually with an integrated plenum This is due to the very clever positioning the sub-elements can be reached each other almost automatically.

By a minimal number of components can be a multi-functionality be ensured of the flow channel.

Preferably are the three sub-elements of the flow channel in series arranged to each other. It proves particularly preferable if the three sub-elements are arranged so that they have a common have straight longitudinal axis. Just such Sequential arrangement allows a particularly effective Realization of the functional principle.

Preferably branches from the second sub-element a line for deriving the deposited liquid. In particular, the branches Line at the transition between the second and the third sub-element off, in particular, is a turnoff at the bottom of the transition intended. As a result, the gravitational effect can be utilized become.

Especially is due to the shape and arrangement of the second and third Subelement at the transition between these components Air space formed in which the separated water collectible is.

Of the Flow channel with its sub-elements is preferably integrally formed.

One Fuel cell system according to the invention a device according to the invention or an advantageous Embodiment thereof. The fuel cell system is in particular designed as a mobile fuel cell system and may preferably be used in a motor vehicle. The fuel cell system includes at least one fuel cell, in particular a fuel cell stack with a plurality of fuel cells, the fuel cells preferably are formed as PEM fuel cells.

at a method according to the invention for depositing a liquid from one in a flow channel flowing gas stream, the liquid is at the Inside a first in the flow direction of the gas stream Sub-element and a subsequent, in the flow direction on its inside at least partially expanding second Part of the flow channel moved along. This movement is effected in particular by the gas flow itself. The liquid is at a stepped transition of the insides between the second sub-element and a subsequent third sub-element collected. All three sub-elements are to guide the Gas stream formed. By such a procedure can improves the separation of liquid from a gas stream take place and in particular without a cyclone separator or a Drahtgestrickabscheider be enabled.

Preferably be the three sub-elements of the flow channel in the axial Direction arranged one behind the other, in particular arranged so that they have a common rectilinear longitudinal axis. Preferably, the collected liquid at the transition drained between the second and the third sub-element.

advantageous Embodiments of the device according to the invention are as advantageous embodiments of the invention View procedure.

embodiments The invention will be described in more detail below with reference to schematic drawings explained. Showing:

1 a schematic sectional view through a first embodiment of a device according to the invention; and

2 a schematic sectional view through a second embodiment of a device according to the invention.

In The figures are the same or functionally identical elements with the provided the same reference numerals.

In 1 is shown in a schematic representation of a cross section through a device I for separating a liquid from a gas stream. The device I is in 1 shown with sub-components, wherein the device I is assigned to a mobile fuel cell system in a motor vehicle. The gas stream flowing through the device I is an exhaust gas flow from the cathode Denraum and / or the anode compartment of a fuel cell or a fuel cell stack.

The device I comprises a flow channel 1 which is a first subelement 2 and a downstream in the flow direction and downstream second sub-element 3 and in turn to the second sub-element 3 immediately following third subelement 4 includes. The three subelements 2 . 3 and 4 are thus arranged in series in the flow direction, which is characterized by the arrow P, and are formed and arranged such that they have a common linear longitudinal axis A.

The first subelement 2 is formed like a tube and has in the embodiment a round cross section, so that an inner dimension d1 is characterized by an inner diameter. In an analogous manner, the second subelement 3 also a pipe section, which has an inner diameter d2 an inner diameter. The second subelement 3 is formed continuously widening in the direction of the longitudinal axis A and thus has a conical inner structure. The widening is in the direction of the third subelement 4 educated. The inner dimension d2 thus assumes in the embodiment, starting from the transition 8a between the first subelement 2 and the second subelement 3 until the transition 8b between the second subelement 3 and the third subelement 4 steadily too.

The third subelement 4 is also formed like a tube and has as inner dimension d3 also an inner diameter.

In addition to a circular cross-section of the first sub-element 2 and / or the second subelement 3 and / or the third subelement 4 can at least one of these sub-elements 2 to 4 also have a different cross-sectional geometry and, for example, be angular or oval or the like.

The first subelement 2 has an inside 5 , the second subelement 3 an inside 6 and the third subelement 4 an inside 7 on. The transition 8a between the inside 5 of the first subelement 2 and the inside 6 of the second subelement 3 is formed in the embodiment shown quasi continuously without a sharp jump.

A transition 8b between the second subelement 3 and the third subelement 4 is formed in the embodiment shown as a sharp discrete step, here the inside 6 essentially vertically to the horizontally oriented inside 7 empties.

The second subelement 3 can also act as a groove in the flow channel 1 be educated. In particular, it is provided that the flow channel 1 is preferably formed in one piece and thus this second sub-element 3 designed as a groove. In particular, this second subelement 3 formed completely circumferentially about the axis A and thus may also be referred to in particular as an annular groove. From the second subelement 3 branches at the bottom of a line 9 for discharging the collected separated water from the gas stream.

In the fuel cell system, it has been observed that the unwanted water in the gas stream in the subelements 2 to 4 All of which are intended to guide the gas flow, especially on the insides 5 . 6 and 7 moved along and it hardly comes to drip inside the gas flow. Therefore, it is no longer necessary here that a wire mesh or a cyclone is used, which initially causes the drops to connect to larger drops and then merges.

In 1 becomes the water 10 through the gas flow on the inside 5 of the first subelement 2 along and ends up in the annular groove or the second partial element formed with a larger inner dimension d2 3 , This is due to the fact that the liquid or the water 10 endeavors, on the inside 5 respectively. 6 to stick. The effect is referred to as the Coanda effect.

The water 10 is determined by gravity and / or the pressure difference between the internal pressure in the flow channel 1 and the pressure at the end of the pipe 9 expelled.

Depending on how much water 10 is believed constructively the depth (vertical direction) and / or length (horizontal direction) of the second sub-element 3 be designed. Likewise, it can also be provided that the second sub-element 3 does not have a cross-sectional tip configuration but the cross-sectional shape, for example, also corner-free, for example, arcuately designed. It can also be provided that the second sub-element 3 is formed only partially circumferentially about the axis A and thus only partially over the radius (d1 / 2) of the first sub-element 2 and one over the radius (d3 / 2) of the third subelement 4 extending radius (d2 / 2) has.

As already mentioned, the inner dimension of the second part element decreases 3 starting from this the first subelement 2 towards the end facing steadily and has at its the third sub-element 4 facing the end of its maximum internal dimension. The transition 8b between the second subelement 2 and the third subelement 4 is in turn stepped, in which context the inside 6 in a vertically oriented inside 12 the rear wall of the second partial element 3 passes over, with this vertical inside 12 on an outside 13 of the third subelement 4 ends. The inner dimension d3 of the third subelement 4 at this transition 8b is smaller than the maximum inner dimension of the second partial element 3 at this transition 8b ,

In addition, the third subelement is 4 arranged so that it is with its the first and the second subelement 2 respectively. 3 facing the end 11 in the interior of the second sub-element 3 hineinerstreckt. By this configuration is between the outside 13 and the inside 6 a collection room in the form of an airspace 14 formed, which back through the inside 12 is completed. A flow through the inside 12 is therefore not possible. The third subelement 4 is thus formed in this embodiment, so to speak, as a "dip tube".

Through the not sharply graded transition 8a between the first subelement 2 and the second subelement 3 This can be prevented on the inside 5 pouring water 10 entrained by the gas flow and from the inside 5 respectively. 6 is replaced and thereby not in the airspace 14 could arrive. Due to the constant expansion and thus the inclined inside 6 This release effect can be prevented in comparison to a sharp discrete staging and the water 10 also flows after the transition 8a along the inside 6 in the direction of the airspace 14 , By getting into the interior of the second sub-element 3 extending third subelement 4 It can be particularly effectively prevented from getting in these air spaces 14 collected water is discharged through the flow again and also through the third sub-element 4 is carried along.

The geometry of the second subelement 3 with regard to the expansion with regard to the sizing of airspace 14 is just an example. In addition, the length with which the third subelement 4 in the interior of the second sub-element 3 extends purely by way of example and may deviate from the representation in 1 be designed otherwise.

Especially on the lower side of the room 14 Can the effective collection of water 10 be made possible because of the gravity quasi container-like. By the third subelement 4 almost like a cover over this room 14 can extend through this area of the third sub-element 4 virtually a Überschwappschutz be guaranteed. In addition, in this embodiment according to 1 a very low pressure loss can be guaranteed.

In 2 is another embodiment of a flow channel 1 for a device I shown in the cross section in contrast to the illustration according to FIG 2 a third subelement 4 which is at the transition 8b to the second subelement 3 ends. In this embodiment, the third sub-element extends 4 thus not in the interior of the second sub-element 3 ,

The statements according to 1 to 3 are preferably all rotationally symmetrical to the axis A. Of course, however, can also be provided, as already for the embodiment in 1 mentions that such a rotationally symmetrical design is not provided. Thus, for example, in the embodiments according to 2 and 3 also be provided that the insides 12 have different vertical lengths above and below the axis A in the cross-sectional views shown. In this regard, an asymmetrical configuration to the axis A would then be designed. Likewise, it can be provided that the second sub-element 3 only widened over a partial length is formed.

Especially when used in a fuel cell system can be used with the device I is an effective separation of the liquid from a gas stream be achieved and in particular at load jumps of the fuel cell system Prevents water retention from components or solve the flow channel and entrained become. This can also be prevented that entrained Water enters the fuel cell stack and there to a functional impairment or to a negative influence during the restart or at the start at low ambient temperatures of the fuel cell system leads.

The However, use of the device I is not on a fuel cell system limited and it can in principle with all systems be used, in which a liquid separation to be made from a gas stream.

1

flow channel

2

first subelement

3

second subelement

4

third subelement

5, 6, 7, 12

inside

8a, 8b

crossing

9

management

10

water

11

The End of the third subelement

13

outside of the third subelement

14

airspace

A

longitudinal axis

d1 d2, d3

Internal dimensions

P

arrow

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 10120018 A1 [0005]
• - DE 102004022245 A1 [0006]

Claims (15)

Device for separating a liquid from a gas stream, having a flow channel ( 1 ), which in the flow direction (P) of the gas flow, a first sub-element ( 2 ) and a second subelement ( 3 ), which at least partially has a larger inner dimension (d2) than the first partial element ( 2 ), and a transition ( 8b ) of the insides ( 6 . 12 . 7 ) between the second subelement ( 3 ) and one to the second subelement ( 3 ) in the flow direction (P) subsequent third sub-element ( 4 ) of the flow channel ( 1 ) is stepped, characterized in that the second sub-element ( 3 ) on its inside ( 6 . 12 ) is formed in the longitudinal direction (A) at least partially widening. Device according to claim 1, characterized in that the second subelement ( 3 ) at its third subelement ( 4 ) adjacent end has its largest internal dimension. Device according to one of the preceding claims, characterized in that the internal dimension (d3) of the third subelement ( 4 ) at the transition ( 8b ) to the second subelement ( 3 ) the inner dimension (d1) of the first partial element ( 2 ) at the transition ( 8a ) to the second subelement ( 3 ) corresponds. Device according to one of the preceding claims, characterized in that the to the third sub-element ( 4 ) opening back wall of the second sub-element ( 3 ) a substantially vertically formed inside ( 12 ) having. Device according to one of the preceding claims, characterized in that at the transition ( 8b ) between the second ( 3 ) and the third subelement ( 4 ) an airspace ( 14 ) is formed as a collecting space for the separated liquid. Device according to one of the preceding claims, characterized in that the second partial element ( 3 ) facing end ( 11 ) of the third subelement ( 4 ) into the interior of the second subelement ( 3 ). Device according to claim 5, characterized in that the end ( 11 ) of the third subelement ( 4 ) so in the interior of the expanded portion of the second partial element ( 3 ) that extends between the outside ( 13 ) of the third subelement ( 4 ) and the inside ( 6 . 12 ) of the second subelement ( 3 ) an airspace ( 14 ) is formed, in which the liquid can be collected from the gas stream is collectable. Device according to one of the preceding claims, characterized in that the three sub-elements ( 2 . 3 . 4 ) are arranged in series with each other. Device according to one of the preceding claims, characterized in that the three sub-elements ( 2 . 3 . 4 ) are arranged so that they have a common longitudinal axis (A). Device according to one of the preceding claims, characterized in that of the second sub-element ( 3 ) a line ( 9 ) branches off to divert the separated liquid. Apparatus according to claim 10, characterized in that the line ( 9 ) at the transition ( 8b ) between the second ( 3 ) and the third subelement ( 4 ) branches off, in particular at the bottom of the transition, branches off. Fuel cell system with a device (I) according to one of the preceding claims. Method for separating a fluid from a fluid in a flow channel ( 1 ) flowing gas stream, wherein the liquid on the inside ( 5 ) of a first partial element in the flow direction (P) of the gas flow ( 2 ) and a following, in the flow direction (P) on its inside ( 6 . 12 ) at least partially in the longitudinal direction (A) expanding second sub-element ( 3 ) of the flow channel ( 1 ) and the liquid is moved along a stepped transition ( 8b ) of the insides ( 6 . 12 . 7 ) between the second subelement ( 3 ) and a subsequent third subelement ( 4 ) is collected. Method according to claim 13, characterized in that the three sub-elements ( 2 . 3 . 4 ) are arranged one behind the other in the axial direction, in particular with a common longitudinal axis (A) are arranged. A method according to claim 13 or 14, characterized in that the collected liquid at the transition ( 8b ) between the second ( 3 ) and the third subelement ( 4 ) is drained.