Liquid separator

Abstract

A liquid separator (10) for separating a liquid from a fluid flow comprises: a housing (11); a flow region (18) disposed within the housing (11) and including an inner pipe (12) and an outer pipe (22) adjacent to the inner pipe (12), the inner pipe (12) being disposed downstream of the outer pipe (22) in a flow direction (80); a fluid conduit (36) connected to the flow region (18) and having a first diameter (D1), the fluid conduit (36) including a swirl flow generating section (26) that generates a swirl flow of the fluid flow; a separation region (24) disposed radially outward of the inner pipe (12) and the outer pipe (22); a liquid outlet (30) connected to the separation region (24) and extending at an angle with respect to an axial direction (82); and a flow relaxation region (20) disposed between the separation region (24) and the liquid outlet (30) and including a flow relaxation element (28) that relaxes the fluid flow.

Description

[Technical Field]

[0001] The present invention relates to a liquid separator for separating a liquid, in particular water, from a fluid stream, in particular an air stream in a fuel cell system, and to a fuel cell system equipped with a liquid separator. [Background technology]

[0002] EP 1167743 discloses a water separator configured as a swirl separator, which comprises an inner pipe and an outer pipe arranged successively along the axial direction, the inner pipe having an axial portion projecting into the outer pipe, and the outer pipe having a water outlet arranged tangentially along the direction of the swirl flow. Summary of the Invention

[0003] SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved liquid separator for separating liquids, particularly water, from an air stream, particularly in a fuel cell system.

[0004] Another object of the present invention is to provide a fuel cell system equipped with such a liquid separator.

[0005] The above object is achieved, according to one embodiment of the present invention, by providing a liquid separator for separating liquid, in particular water, from a fluid flow, in particular an air flow of a fuel cell system, the liquid separator comprising at least one separation stage, the separation stage comprising a housing having a flow area connected to a fluid conduit having a first diameter, the flow area including at least one inner tube and at least one outer tube arranged axially relative to one another, the inner tube being arranged downstream of the outer tube in the flow direction and adjacent to the outer tube, a swirl generator for generating a swirl flow of the fluid flow being provided in the fluid conduit, and a swirl generator for generating a swirl flow of the fluid flow being provided radially outward of the inner and outer tubes the outer pipe has an inlet region continuous with the flow direction and a conical and / or tulip-shaped region, the inlet region being connected to a fluid conduit, the conical region having a downstream second diameter, the inner pipe being formed in a conical shape and having an upstream third diameter, and a flow relaxation region having at least one flow relaxation element being provided between the separation region and the liquid outlet, the liquid outlet extending at an angle to the axial direction and having an outlet opening preferably extending in the opposite direction to the flow direction, the outer pipe having an inlet region continuous with the flow direction and a conical and / or tulip-shaped region, the inlet region being connected to a fluid conduit, the conical region having a downstream second diameter, the inner pipe being formed in a conical shape and having an upstream third diameter, and a flow relaxation region having at least one flow relaxation element being provided between the separation region and the liquid outlet.

[0006] According to a further aspect of the invention, at least one conical region is at least partially cylindrically shaped.

[0007] According to a further aspect of the present invention, the above object is solved by a fuel cell system comprising a cathode supply air passage and a cathode exhaust air passage of a fuel cell unit, and at least one liquid separator.

[0008] Advantageous embodiments and advantages of the invention can be obtained from the accompanying claims, the description and the drawings.

[0009] According to one aspect of the present invention, a separator for separating a liquid, particularly water, from a fluid flow, particularly an air flow in a fuel cell system, is provided. The separator includes at least one separation stage, the separation stage comprising a housing having a flow area connected to a fluid conduit having a first diameter. The flow area includes at least one inner tube and at least one outer tube arranged axially relative to each other. The inner tube is arranged adjacent to the outer tube downstream of the outer tube in the flow direction. A swirl generator for generating a swirling flow of the fluid flow is provided within the fluid conduit. The separation area is provided radially outward of the inner and outer tubes and is connected to a liquid outlet. The liquid outlet extends at an angle to the axial direction, and its outlet opening preferably extends in the opposite direction to the flow direction. The outer tube has an inlet area continuous with the flow direction and a conical and / or tulip-shaped area, and the inlet area is connected to the fluid conduit. The conical area has a second downstream diameter. The inner tube is formed in a conical and / or tulip shape and has a third upstream diameter. In this case, a flow relaxation region having at least one flow relaxation element is provided between the separation region and the liquid outlet.

[0010] According to a further aspect of the invention, at least one conical region is at least partially cylindrically shaped.

[0011] Advantageously, the proposed component can be used to separate liquid from an air or gas stream, for example, in the cathode air channel or exhaust of a fuel cell system. For example, water produced by the reaction of hydrogen and oxygen in a fuel cell system exists in a two-phase flow and can be appropriately separated by a water separator.

[0012] Advantageously, the liquid separator is configured as a swirl separator, and in the intended state, the liquid outlet is inclined with respect to the axial direction, the outlet opening preferably extending in the opposite direction to the flow direction. Advantageously, the liquid separator comprises an inner pipe and an outer pipe arranged consecutively along the axial direction, the inner pipe having a smaller diameter than the outer pipe at the transition to the outer pipe, so that the flow area between the outer and inner pipes is configured for swirl separation.

[0013] A fluid flow, particularly air, is supplied to the separation stage through a fluid conduit having a first diameter and a swirl generator disposed therein for generating a swirl flow in the fluid flow. The fluid flows through a flow area inside an outer tube, which has a conical and / or tulip-shaped region that opens in a funnel shape in the flow direction and has an outlet diameter of a second diameter. An inner tube is disposed adjacent to the outer tube, which is also conical and / or tulip-shaped and opens in a funnel shape in the flow direction. However, the inlet diameter (third diameter) and outlet diameter of the inner tube are smaller than those of the outer tube. This arrangement of the outer and inner tubes forms a velocity reduction region in the inner tube. A separation region is disposed inside the liquid separator housing, radially outward of the conical region of the outer tube and the inner tube, where the separated liquid collects and is supplied to a liquid outlet via a flow relaxation region.

[0014] The flow reduction region includes at least one flow reduction element that reduces the swirl of the fluid flow so that the separated liquid can easily reach the liquid outlet. The flow reduction element can be, for example, a rib that is positioned across the swirl of the fluid flow to block the swirl. Alternatively, the flow reduction element can be a grid that is positioned between the separation region and the flow reduction region and configured as a permeable separation wall that blocks the swirl of the fluid flow.

[0015] This liquid separator effectively separates and allows the liquid component that appears as a wall film in the fluid stream after the first separation stage to flow out, thereby improving separation performance. Thus, unlike the prior art, this liquid separator provides improved functional separation performance while reducing pressure drop.

[0016] The proposed liquid separator comprises a separation stage having an outer tube and an inner tube. Advantageously, multiple separation stages can be arranged in a modular arrangement to improve the degree of separation. Thus, the liquid separator can comprise, for example, two or four series-connected separation stages.

[0017] Advantageously, the liquid separator can be operated in a horizontal or vertical installation, for example in a vehicle fuel cell system, but the liquid separator can also be operated at an angle relative to the horizontal.

[0018] Advantageously, the liquid separator is made from a plastic material and can be manufactured, for example, by conventional injection molding methods. Preferably, at least the liquid outlet is made from a plastic material.

[0019] In another advantageous embodiment, the liquid separator is manufactured by a 3D printing method or as a sintered metal part.

[0020] Advantageously, the swirl generator is formed integrally with the fluid conduit, which allows the liquid separator to be manufactured at low cost. Alternatively, the swirl generator can be replaceably arranged within the fluid conduit and replaced as required.

[0021] In the case of a multi-stage liquid separator, the separation stages of the liquid separator are advantageously manufactured as modular components that are used in combination with one or more further liquid separators, in which case the housings of the individual separation stages can be connected, for example, by welding or gluing.

[0022] According to an advantageous embodiment of the liquid separator, the third diameter is smaller than the first diameter, which is smaller than the second diameter, such that the fluid flow in the inner pipe is slowed down in an appropriate manner, thereby allowing for an advantageous separation of liquid, in particular water, in the conical and / or tulip-shaped region of the outer pipe and for the separation to continue in a separation region located radially outside the conical and / or tulip-shaped regions of the inner and outer pipes.

[0023] According to an advantageous embodiment of the liquid separator, the flow mitigation elements are configured as ribs extending along the inner wall of the flow mitigation area to the liquid outlet. In particular, the ribs are configured to extend to the bottom of the inner wall in the intended installed state. Advantageously, the ribs are arranged transverse to the swirl of the fluid flow, thereby suppressing the swirl of the fluid flow and allowing the separated liquid to easily reach the drain.

[0024] According to an advantageous embodiment of the liquid separator, the flow relaxation element is configured as a grid arranged in an annular shape around the outer pipe and separating the separation zone from the flow relaxation zone. In particular, the flow relaxation element can have a convexly curved shape when viewed in the flow direction. Alternatively, the flow relaxation element can be designed as a grid arranged between the separation zone and the flow relaxation zone. For example, the grid can be arranged around the outer pipe in the shape of an open torus. This prevents swirling of the fluid flow and allows the separated liquid to easily reach the drain.

[0025] According to an advantageous embodiment of the liquid separator, the ratio of the second diameter to the third diameter is ≧1 and ≦3, preferably ≧1.5 and ≦2. This allows advantageously setting the ratio of the outlet diameter of the conical and / or tulip-shaped region of the outer tube to the inlet diameter of the inner tube, which advantageously influences the fluid and improves the separation rate of the liquid.

[0026] According to an advantageous embodiment of the liquid separator, the axial distance between the inner and outer pipes is in the range of -20 mm to +20 mm, with the negative distance being the case when the inner pipe 12 is inserted into the outer pipe 22. In particular, the distance can be 0 mm, so that the inner pipe is only slightly inserted into the outer pipe or is positioned at a substantially minimum distance relative to the outer pipe, which has a beneficial effect on the fluid and improves the separation rate of the liquid.

[0027] According to an advantageous embodiment of the liquid separator, the ratio of the length of the inner tube to the length of the outer tube is ≧0.1 and ≦1, preferably ≧0.3 and ≦0.4. Advantageously, the inner tube is configured to have a significantly reduced length compared to the outer tube, which can have a beneficial effect on the fluid and improve the separation rate of the liquid.

[0028] According to an advantageous embodiment of the liquid separator, the conical inner tube has a cone half angle ranging from -10° to +20°. The cone shape of the inner tube can be configured in this way from a widening funnel shape to a narrowing funnel shape, which has a beneficial effect on the fluid and improves the liquid separation rate.

[0029] According to an advantageous embodiment of the liquid separator, the conical region of the outer pipe has a cone half angle in the range of -10° to +20°. The cone shape of the outer pipe can also be configured in this way from a widening funnel shape to a narrowing funnel shape, which can have a beneficial effect on the fluid and improve the liquid separation rate.

[0030] According to an advantageous embodiment of the liquid separator, the half angle of the cone of the inlet region of the outer pipe is in the range of 0° to +10°. The cone shape of the inlet region of the outer pipe can be varied in this narrow angle range, which has a beneficial effect on the fluid and improves the separation rate of the liquid.

[0031] According to an advantageous embodiment of the liquid separator, the inclination angle of the liquid discharge surface of the flow relaxation area is in the range of 0° to 60°, preferably 30°, with respect to the direction of gravity in the intended installation state, thereby ensuring a good discharge of the separated liquid during the intended operation of the liquid separator.

[0032] According to an advantageous embodiment of the liquid separator, in the intended horizontal installation state, the side surfaces of the flow relief area can be inclined towards the axial direction in the flow direction, and in the intended vertical installation state, the liquid discharge side surfaces can be inclined away from the axial direction in the flow direction, thereby ensuring a good discharge of the separated liquid during the intended operation of the liquid separator.

[0033] According to an advantageous embodiment, a liquid drain opening can be located at the geodetic lowest point of the hub of the swirl flow generator, especially when the liquid separator is installed vertically. This liquid drain opening prevents liquid from accumulating inside the hub, for example, if the hub has an internal recess or cavity, especially when manufactured as an injection-molded part. Liquid accumulation must be prevented due to the thermal behavior of liquids, particularly the volume expansion of water at low temperatures. The liquid drain opening has a diameter as small as possible to prevent bypass flow through the hub to the swirl flow generator, while being large enough to allow the liquid to flow out of the opening due to surface tension. Preferably, the opening, especially the water drain opening, has a diameter of 2 mm or more, or a surface area equivalent to 2 mm in the case of a non-circular cross section. For small liquid separators, the liquid drain opening may have a diameter up to the inner diameter of the hub.

[0034] According to an advantageous embodiment, the liquid separator comprises at least two separation stages arranged in succession in the flow direction, with the outer and inner tubes arranged adjacent to each other. Advantageously, a modular arrangement of multiple separation stages can be used to improve the degree of separation. Thus, the liquid separator can comprise, for example, two or four series-connected separation stages.

[0035] According to an advantageous embodiment, if separation stages follow one another in the flow direction, these separation stages are identical or at least substantially identical to one another. Advantageously, a modular arrangement of several identical or at least substantially identical separation stages next to one another can improve the degree of separation. Thus, a liquid separator can comprise, for example, two or four series-connected separation stages. The housings of the individual separation stages are preferably connected to one another by welding or gluing in order to obtain tightly sealed fluid conduits.

[0036] According to a further aspect of the invention, a fuel cell system is proposed comprising a cathode supply air channel and a cathode exhaust air channel of a fuel cell unit and at least one liquid separator.

[0037] Advantageously, a liquid separator can be used to separate liquids, particularly water, from the air or gas stream, for example, in the cathode air channel or exhaust of a fuel cell system. For example, water produced by the reaction of hydrogen and oxygen in a fuel cell system exists in a two-phase flow and is suitably separated by a water separator.

[0038] In another aspect of the invention, a liquid separator may be inserted into the anode air path of the fuel cell system.

[0039] Further advantages can be obtained from the following description of the drawings, in which embodiments of the invention are shown. The drawings, the description, and the claims contain a number of features in combination. Those skilled in the art can consider these features appropriately and individually and combine them to provide further combinations, as shown below by way of example. [Brief explanation of the drawings]

[0040] [Figure 1] 1 is a longitudinal cross-sectional view of a liquid separator having a separation stage according to one embodiment of the present invention, operating horizontally; [Figure 2] FIG. 2 is a schematic diagram illustrating exemplary geometric dimensions of the liquid separator shown in FIG. 1. [Figure 3] 10 is a side view of a liquid separator having two separation stages according to a further embodiment of the invention, operating horizontally. FIG. [Figure 4] FIG. 4 is a vertical cross-sectional view of the liquid separator shown in FIG. [Figure 5] 10 is a longitudinal section of a liquid separator having four separation stages according to a further embodiment of the invention, operating horizontally. FIG. [Figure 6] 2 is an isometric view of the inside of the inner pipe of the liquid separator shown in FIG. 1, viewed from the direction of flow. [Figure 7] 2 is an isometric view of the inside of the outer tube of the liquid separator shown in FIG. 1, viewed from the opposite direction to the flow direction. [Figure 8] 1 is a longitudinal section of a liquid separator having a separation stage according to a further embodiment of the invention, operating vertically; [Figure 9] 4 is a longitudinal section of a liquid separator having two separation stages according to a further embodiment of the invention, operating vertically. FIG. [Figure 10] 1 is a simplified diagram of a fuel cell system having a cathode supply air passage and a cathode exhaust air passage. DETAILED DESCRIPTION OF THE INVENTION

[0041] In the figures, identical or similar components are designated with identical reference symbols.The figures are merely illustrative and should not be understood as limiting.

[0042] FIG. 1 is a longitudinal cross-sectional view of one embodiment of a horizontally operating liquid separator as liquid separator 10 having a separation stage 50 according to one embodiment of the present invention.

[0043] The water separator 10 is used to separate water from a fluid stream, particularly an air stream in a fuel cell system. The water separator 10 includes a separation stage 50 comprising a housing 11 having a flow area 18 connected to a fluid conduit 36 ​​having a first diameter D1. The flow area 18 includes an inner tube 12 and an outer tube 22 arranged axially relative to one another in a flow direction 80. The inner tube 12 is positioned downstream of and adjacent to the outer tube 22 in a flow direction 80. The fluid flow is supplied to the fluid conduit 36 ​​at an inlet 38 and exits the water separator 10 at an outlet 40 of the fluid conduit 36 ​​at the other end of the housing 11.

[0044] A swirl flow generating section 26 that generates a swirl flow of the fluid flow is disposed within the fluid conduit 36. The swirl flow generating section 26 may be formed integrally with the fluid conduit 36 ​​or may be configured to be replaceable. This forms the flow region 18 for swirling and separating water from the fluid flow.

[0045] The separation region 24 is provided radially outward of the inner pipe 12 and the outer pipe 22 and is connected to the water outlet 30. The water outlet 30 extends at an angle to the axial direction 82, and its outlet opening extends in the opposite direction to the flow direction 80.

[0046] The outer pipe 22 includes an inlet region 21 and a conical region 23 that are continuous in the flow direction 80. The inlet region 21 is connected to the fluid conduit 36. The conical region 23 widens in a funnel-like, particularly tulip-like, shape along the flow direction 80 and has a downstream second diameter D2 as an outlet diameter that is larger than the first diameter D1 of the fluid conduit 36.

[0047] The inner pipe 12 is configured in a conical shape and has an upstream third diameter D3 as an inlet diameter, which is smaller than the outlet diameter D1, so that the inner pipe 12 also widens in the flow direction like a funnel.

[0048] Between the separation region 24 and the water outlet 30, a flow relief region 20 is arranged, which has at least one flow relief element 28. The flow relief element 28 is designed as a rib 32 and extends along the inner wall of the flow relief region 20 to the water outlet 30. In particular, the rib 32 extends to the bottom of the inner wall in the intended installed state.

[0049] The sides 42 of the flow relief area 20 are angled in the flow direction 80 toward the axial direction 82 in the intended horizontal installation.

[0050] The water separator 10 may be secured in, for example, the fuel cell system 100 by a number of mounting flanges 44 (only one of which is shown in FIG. 1).

[0051] A fluid flow, particularly air, is supplied to the separation stage 50 through a fluid conduit 36 ​​having a first diameter D1 and a swirl generator 26 for generating a swirl flow in the fluid flow. The fluid flows through a flow region 18 inside the outer tube 22, which has a conical region 23 that opens in a funnel shape in the flow direction 18 and has a second diameter D2 as an outlet diameter. The inner tube 12 is arranged adjacent to the outer tube 22 and is similarly conically shaped, opening in a funnel shape in the flow direction 80. However, the inlet diameter (third diameter D3) and outlet diameter D1 of the inner tube 12 are smaller than the outlet diameter D2 of the outer tube 22. This arrangement of the outer tube 22 and the inner tube 12 forms a velocity reduction region 14 in the inner tube 12. A separation region 24 is located inside the housing 11 of the liquid separator 10, radially outward of the conical region 23 of the outer tube 22 and the inner tube 12. Separated water collects and is supplied to the water outlet 30 via the flow relaxation region 20.

[0052] FIG. 2 is a schematic diagram showing the geometric dimensions of the water separator 10 of FIG.

[0053] The dimension and ratio ranges identified in Figure 2 provide particularly advantageous embodiments for achieving good separation in the water separator 10 with the separation stage 50 of the present invention. However, good water separation can also be achieved with different dimension and ratio ranges.

[0054] Advantageously, the ratio of the second diameter D2 to the third diameter D3 is ≧1 and ≦3, preferably ≧1.5 and ≦2.

[0055] Housing 11 has an inner diameter D4. Swirl flow generator 26 includes a swirl flow generator hub 27 having a diameter D5.

[0056] Furthermore, the axial distance X1 between the inner pipe 12 and the outer pipe 22 is advantageously in the range of −20 mm to +20 mm, with the case where the inner pipe 12 is inserted into the outer pipe 22 being taken as a negative distance X1. The distance X1 is preferably 0 mm.

[0057] Furthermore, it is advantageous that the ratio of the length X2 of the inner tube 12 to the length X3 of the outer tube 22 is greater than or equal to 0.1 and less than or equal to 1, preferably greater than or equal to 0.3 and less than or equal to 0.4.

[0058] The half angle of the cone A1 of the conical inner tube 12 is advantageously in the range of -10° to +20°.

[0059] The half angle of the cone A2 of the conical region 23 of the outer bulb 22 is advantageously in the range of -10° to +20°.

[0060] The half angle of the cone A3 of the inlet area 21 of the outer tube 22 is advantageously in the range 0° to +10°.

[0061] The embodiment of the water separator 10 shown in FIG. 1 may have, for example, the following dimensions as defined in FIG.

[0062] Half angle of the cone of the inner tube 12: A1 = 8.5°

[0063] Half angle of the cone of the conical region 23 of the outer tube 22: = 19.5°

[0064] Half angle of the cone of the inlet region 21 of the outer tube 22: A3 = 1.4°

[0065] Diameter of fluid conduit 36: D1 = 52 mm

[0066] Outlet diameter of outer tube 22: D2 = 68 mm

[0067] Inlet diameter of inner pipe 12: D3 = 42 mm

[0068] Diameter of housing 11: D4 = 100 mm

[0069] Diameter of swirl flow generating part hub 27: D5 = 15.4 mm

[0070] Diameter of water outlet 30: D6 = 15 mm

[0071] Total length of the water separator 10: L1 = 200 mm

[0072] Distance from outer tube 22 to fluid conduit 36: L2 = 38 mm

[0073] Length of cone region 23: L3 = 21.7 mm

[0074] Distance from the swirl flow generating hub 27 to the conical region 23: L4 = 55.3 mm

[0075] Radius of the transition between the inlet region 21 and the conical region 23: R1 = 75 mm

[0076] Distance between outer tube 22 and inner tube 12: X1 = 0 mm

[0077] Length of inner tube 12: X2 = 21 mm

[0078] Length of outer tube 22: X3 = 29.5 mm

[0079] The angle of inclination of the water discharge side surface 42 of the flow mitigation area 20 in the intended installation state is advantageously in the range of 0° to 60° with respect to the direction of gravity 60, and particularly preferably 30°, and is adapted to the respective installation situation.

[0080] 3 is a side view of a water separator 10 operating horizontally and having two separation stages 50 according to a further embodiment of the invention. FIG. 4 is a longitudinal cross-sectional view of the water separator 10.

[0081] In this embodiment, two separation stages 50 are arranged consecutively in the flow direction 80 within the water separator 10, with the outer pipes 22 and the inner pipes 12 arranged alternately adjacent to each other. The separation stages 50 arranged consecutively in the flow direction 80 each have the same structure. A swirl flow generator 26 is arranged in the fluid conduit upstream of the first separation stage 50. On the other hand, no additional swirl flow generator 26 is arranged upstream of the second separation stage 50. Each separation stage 50 has its own water outlet 30. By arranging the two separation stages 50 consecutively, more efficient water separation can be achieved.

[0082] 5 is a vertical cross-sectional view of a water separator 10 according to a further embodiment of the present invention, which operates horizontally and has four separation stages 50. With four successively arranged separation stages 50, more efficient water separation can be achieved.

[0083] Figure 6 is an inside isometric view of the inner pipe 12 of the water separator 10 shown in Figure 1, viewed in the direction of flow 80. Only a portion of the water separator 10 is shown, including the inner pipe 12 and the fluid conduit 36 ​​having the outlet 40 leading downstream.

[0084] The lower portion of the housing 11 shows a flow relief area 20 having a downwardly sloping sidewall 42. To break up the swirling flow, ribs 32 extend from the bottom of the inner wall of the flow relief area 20 as flow relief elements 28.

[0085] The housing 11 includes three mounting flanges 44 arranged in a triangle.

[0086] Figure 7 is an isometric view of the inside of the outer pipe 22 of the water separator 10 shown in Figure 1, viewed from the opposite direction to the flow direction 80. Other parts of the water separator 10 are shown here, including the outer pipe 22 and the swirl flow generator 26 located aft of it.

[0087] At the bottom of the housing 11, water outlets 30 and ribs 32 located in the flow relief area 20 can be seen.

[0088] Furthermore, it can be seen that the outer tube 22 opens out in a funnel shape from the inlet region 21 via a conical region 23 .

[0089] FIG. 8 is a longitudinal cross-sectional view of a water separator 10 having a separation stage 50 according to a further embodiment of the invention, operating vertically.

[0090] The main configuration of the water separator 10 is the same as the embodiment for horizontal operation shown in Figure 1. Only the arrangement of the flow relief area 20 with the water outlet 30 differs. The water outlet side 42 is inclined away from the axial direction 82 in the flow direction 80 in the intended vertical installation to achieve a particularly compact configuration.

[0091] The flow mitigation elements 28 are configured as a grid 34 arranged annularly around the outer pipe 22 and separating the separation region 24 from the flow mitigation region 20. In particular, the grid 34 is convexly curved when viewed in the flow direction 80. Alternatively, the grid 34 can be arranged in a torus shape around the outer pipe 22.

[0092] When the water separator 10 is installed or operated vertically, a liquid drain opening 29 is provided at the geodetic lowest point of the hub 27 of the swirl flow generator 26. The liquid drain opening 29 prevents liquid from accumulating inside the hub. The liquid drain opening 29 has a cross section large enough to prevent bypass flow to the swirl flow generator 26 through the swirl flow generator hub 27, on the one hand, and to allow liquid to be discharged from the opening 29 due to surface tension, on the other hand. In particular, the diameter of the water drain opening 29 is preferably 2 mm or more.

[0093] FIG. 9 is a longitudinal cross-sectional view of a water separator 10 having two separation stages 50 according to a further embodiment of the invention, operating vertically.

[0094] In this embodiment, two separation stages 50 are arranged consecutively in the flow direction 80 within the water separator 10, with the outer pipes 22 and inner pipes 12 arranged alternately adjacent to each other. The separation stages 50 arranged consecutively in the flow direction 80 each have the same structure. A swirl flow generator 26 is arranged in the fluid conduit in front of the first separation stage 50. Each separation stage 50 has its own water outlet 30. By arranging the two separation stages 50 consecutively, more efficient water separation can be achieved.

[0095] 10 is a simplified diagram of a commonly known fuel cell system 100 including a fuel cell unit 120 having a cathode supply air passage 122 and a cathode exhaust air passage 124. Ambient air is supplied to the fuel cell unit 120 from the cathode supply air passage 122, filtered in the purification stage 102, and drawn in and compressed by a compressor or pump 110. The compressed air is cooled in a heat exchanger 104 and given a desired humidity level by a humidifier 106.

[0096] In the fuel cell unit 120, oxygen in the air reacts with hydrogen to produce water, which is discharged from the fuel cell unit 120 as an air / water mixture through the cathode discharge air passage 124. The cathode discharge air can transfer some of its moisture to the cathode supply air via the humidifier 106. Connected downstream of the humidifier 106 is the water separator 10, which can be configured according to the above-described embodiments. The separated water is discharged to a drain passage 130, and the dried cathode discharge air is supplied to the compressor turbine or pump 110. It is particularly advantageous to locate the water separator 10 upstream of the compressor turbine or pump 110.

[0097] A further water separator 10 is arranged in the fuel cell system 100 . [Explanation of symbols]

[0098] 10 Water separator 11. Housing 12 Inner tube 14 Deceleration area 16 Sections 18 Distribution area 20 Flow relaxation region 21 Inflow area 22 Outer tube 23 Cone Region 24 Separation area 26 Swirl flow generation part 27 Swirl flow generating hub 28 Flow mitigation elements 29 Drain opening 30 Water outlet 31 Axial 32 Ribs 34 Lattice 36 Fluid conduit 38 Inlet 40 Outlet 42 Side 44 Mounting flange 50 separation stage 60 Gravity direction 80 Flow direction 82 Axial 100 Fuel Cell System 102 Purification Stage 104 Heat exchanger 106 Humidifier 110 Pump 120 fuel cell unit 122 cathode supply air passage 124 Cathode exhaust air passage 130 Drainage Channel A1 Half angle of the inner tube cone A2 Half angle of the cone of the outer tube conical area A3 Half angle of the cone in the inlet region of the outer pipe D1 Diameter of the fluid conduit at the inlet D2 Outer pipe outlet diameter D3 Inlet diameter of inner pipe D4 Housing diameter D5 Diameter of the hub of the swirl flow generating part D6 Drain diameter L1 Total length of water separator L2 Distance from the outer pipe outlet to the fluid conduit L3 Length of the cone region L4 Distance from the fluid conduit to the cone region R1 Radius of the transition between the inlet and cone regions X1 Distance between outer and inner pipes X2 Inner pipe length X3 Outer tube length

Claims

1. A liquid separator (10) for separating a liquid from a fluid stream, comprising: The liquid separator (10) comprises: a housing (11); a flow region (18) disposed within the housing (11) and including an inner pipe (12) and an outer pipe (22) adjacent to the inner pipe (12), the inner pipe (12) being disposed downstream of the outer pipe (22) in a flow direction (80); a fluid conduit (36) connected to the flow region (18) and having a first diameter (D1), the fluid conduit (36) including a swirl flow generating portion (26) that generates a swirl flow of the fluid flow; a separation region (24) disposed radially outside the inner tube (12) and the outer tube (22); a liquid outlet (30) connected to the separation region (24) and extending at an angle to the axial direction (82); the outer pipe (22) has an inlet region (21) and a conical and / or tulip-shaped region (23) arranged downstream of the inlet region (21) in the flow direction (80), the inlet region (21) being connected to the fluid conduit (36), the conical and / or tulip-shaped region (23) having a downstream second diameter (D2); the inner tube (12) is conical and / or tulip-shaped and has an upstream third diameter (D3); The liquid separator (10) comprises: A liquid separator comprising a flow relaxation region (20) disposed between the separation region (24) and the liquid outlet (30), the flow relaxation region (20) including flow relaxation elements (28) that moderate the fluid flow.

2. the upstream third diameter (D3) is smaller than the first diameter (D1); 2. A liquid separator according to claim 1, wherein the first diameter (D1) is smaller than the downstream second diameter (D2).

3. 3. A liquid separator according to claim 1 or 2, wherein the flow mitigation element (28) includes ribs (32) extending along the inner wall of the flow mitigation area (20) to the liquid outlet (30).

4. 3. The liquid separator of claim 1, wherein the flow mitigation element includes a grid arranged annularly around the outer tube and separating the separation region from the flow mitigation region.

5. A liquid separator according to any one of claims 1 to 4, wherein the ratio of the downstream second diameter (D2) to the upstream third diameter (D3) is ≧1 and ≦3.

6. 6. The liquid separator according to claim 1, wherein an axial distance (X1) between the inner pipe (12) and the outer pipe (22) is in the range of −20 mm to +20 mm, where X1 is a negative distance when the inner pipe (12) is inserted into the outer pipe (22).

7. A liquid separator according to any one of claims 1 to 6, wherein the ratio of the length (X2) of the inner pipe (12) to the length (X3) of the outer pipe (22) is greater than or equal to 0.1 and less than or equal to 1.

8. The liquid separator according to any one of claims 1 to 7, wherein the half angle of the cone (A1) of the conical inner pipe (12) is in the range of -10° to +20°.

9. A liquid separator according to any one of claims 1 to 8, wherein the half angle of the cone (A2) of the conical region (23) of the outer tube (22) is in the range of -10° to +20°.

10. Liquid separator according to any one of the preceding claims, wherein the half angle of the cone (A3) of the inlet region (21) of the outer pipe (22) is in the range of 0° to +10°.

11. The liquid separator according to any one of claims 1 to 10, wherein the inclination angle of the liquid discharge side surface (42) of the flow relaxation area (20) is in the range of 0° to 60° with respect to the direction of gravity (60).

12. When placed horizontally, the liquid discharge side surface (42) of the flow relaxation area (20) is inclined in the flow direction (80) so as to approach the axial direction (82), 12. The liquid separator of claim 11, wherein, when installed vertically, the liquid discharge side (42) slopes away from the axial direction (82) in the flow direction (80).

13. The liquid separator comprises: a second flow region (18) disposed within the housing (11) and including a second inner pipe (12) and a second outer pipe (22) adjacent to the second inner pipe (12), the second inner pipe (12) being connected downstream of the flow region (18) in the flow direction (80), the second inner pipe (12) being disposed downstream of the second outer pipe (22) in the flow direction (80); the fluid conduit (36) is connected to the second flow area (18); The liquid separator comprises: a second separation region (24) disposed radially outward of the second inner tube (12) and the second outer tube (22); a second liquid outlet (30) connected to the second separation region (24) and extending obliquely relative to the axial direction (82); 13. A liquid separator according to any one of claims 1 to 12, further comprising a second flow reduction region (20) disposed between the second separation region (24) and the second liquid outlet (30), the second flow reduction region (20) having second flow reduction elements (28) that reduce the fluid flow.

14. A fuel cell system (100), comprising: a cathode supply air passage (122) and a cathode exhaust air passage (124) of the fuel cell unit (120); A liquid separator (10) according to any one of claims 1 to 13 for separating water from the air flow in the cathode supply air passage (122) or the cathode exhaust air passage (124).

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