Blower for a fuel cell array

Abstract

A blower (1) for a fuel cell assembly for recirculating a gas mixture used for operating the fuel cell assembly is equipped with a drive motor (7, 8, 9) comprising a rotor (9) coupled to a motor shaft (7) and a stator (8) arranged radially outside the rotor (9). An annular channel (10) is provided radially between the rotor (9) and the stator (8) for conveying the gas mixture from an inlet side to an outlet side of the annular channel (10). A blower impeller (5) coupled to the motor shaft (7) is provided in the region of the outlet side of the annular channel (10) to convey the gas mixture from the inlet side to the outlet side of the annular channel (10) when rotating. Furthermore, a flow guide device (14) is provided to impart a circumferential swirl to the gas mixture entering the annular channel (10).Furthermore, an arrangement for separating water from the gas mixture is provided, which has at least a section-wise radial widening of the radially outer wall of the annular channel (10).

Description

Technical area

[0001] The present invention relates to a blower for a fuel cell assembly for recirculating a gas mixture used to operate the fuel cell assembly. In particular, the present invention relates to a blower that enables the separation of water from the gas mixture. Furthermore, the invention relates to a fuel cell assembly with such a blower. State of the art

[0002] Fuel cells of various designs are used for stationary and mobile applications. In such known fuel cells, which use hydrogen as the energy carrier, there is a need to convey gaseous media. In particular, fuel cells with an anode region and a cathode region are known, with hydrogen being recirculated from the anode region to ensure the function of the fuel cell. For this purpose, fans designed to convey the corresponding gaseous medium are used in the prior art.

[0003] The object of the invention is to provide an improved blower that can ensure the proper functioning of the fuel cell system. This object is achieved by the features of the claims. Description of the invention

[0004] According to one aspect, the present invention relates to a blower for a fuel cell assembly. The blower for a fuel cell assembly is provided for recirculating a gas mixture used to operate the fuel cell assembly. The blower has a drive motor that has a rotor coupled to a motor shaft and a stator arranged radially outside the rotor.

[0005] In this case, an annular channel is provided radially between the rotor and the stator for conveying the gas mixture from an inlet side to an outlet side of the annular channel, wherein in the region of the outlet side of the annular channel a fan impeller coupled to the motor shaft is provided in order to convey the gas mixture from the inlet side to the outlet side of the annular channel during rotation.

[0006] The blower further comprises a flow guiding device which is provided in the region of the inlet side of the annular channel and is designed to impart a swirl in the circumferential direction of the annular channel to the gas mixture entering the annular channel.

[0007] The blower further comprises an arrangement for separating water from the gas mixture, wherein the arrangement for separating water from the gas mixture comprises an at least partially radial widening of the radially outer wall of the annular channel.

[0008] The blower can be used to recirculate a gas mixture associated with an anode region of the fuel cell assembly. The gas mixture can contain hydrogen. The gas mixture can also contain other components that can result, in particular, from the reaction of the hydrogen in the anode region of the fuel cell assembly. The gas mixture can contain water, which results from the reaction of the hydrogen. The gas mixture can be passed through the anode region of the fuel cell assembly.

[0009] The blower can be connected to a fuel cell module via appropriate piping within the fuel cell assembly such that the blower can direct the gas mixture through the anode region of the fuel cell assembly. The blower can also be connected to a hydrogen source, via which the hydrogen content of the recirculated gas mixture can be adjusted. The blower can be operated by a drive motor, which can be configured as an electric motor. The electric motor can be a brushless motor. The drive motor can be a media gap motor. In this case, the medium conveyed by the blower, in particular the gas mixture used in the fuel cell assembly, can be conveyed through the annular channel. The annular channel can have a cylindrical inner wall and a cylindrical outer wall.The gas mixture can flow from the inlet side to the outlet side between the cylindrical inner wall and the cylindrical outer wall of the annular channel. The inner wall of the annular channel can be formed by the rotor of the drive motor. The stator of the drive motor can be provided outside the outer wall of the annular channel. The outer wall can be formed by an outer tube.

[0010] The fan impeller coupled to the motor shaft can be arranged on the outlet side of the annular channel such that the gas mixture can be conveyed through the annular channel upon rotation of the fan impeller. The fan impeller can have an arrangement of blades distributed around the circumference of the fan impeller. By rotating the fan impeller, the gas mixture can be conveyed based on a corresponding pumping function. Due to its rotation, the fan impeller can convey the gas mixture in a radial direction relative to the annular channel.

[0011] The flow guide device can be provided in the region of the inlet side of the annular channel and configured such that a swirl in the circumferential direction of the annular channel is generated on the gas mixture entering the annular channel, which swirls the gas mixture around the inner wall of the annular channel. In particular, the flow guide device can be configured such that the gas mixture is moved through the annular channel along streamlines that have a circumferential velocity component. Due to the superposition of the circumferential velocity component with an axial velocity component, the gas mixture can be conveyed in a helical shape around the inner wall of the annular channel. In this respect, the flow guide device is designed such that a swirl can be generated to form helical streamlines of the gas mixture around the longitudinal axis of the annular channel.Due to the swirl imposed on the conveyed gas mixture by the flow guide device, a centrifugal force is imposed on the components of the gas mixture, which causes components with a higher density of the gas mixture to move radially outwards within the annular channel.

[0012] The arrangement for separating water from the gas mixture can be provided to separate water generated by the reaction of the hydrogen in the fuel cell assembly. The accumulation of water within a fuel cell system, including the fan and other elements, should be avoided as far as possible. In particular, accumulated water can freeze into ice at low temperatures and disrupt the function of the fuel cell assembly.

[0013] The arrangement for separating water from the gas mixture comprises the at least partially radial widening of the radially outer wall of the annular channel, which is associated with the swirl imposed on the gas mixture. As described above, the swirl imposed on the gas mixture can cause elements of the gas mixture with higher density to move to a radially outer region in the annular channel. The gas mixture can contain liquid water, which is moved radially outward within the annular channel due to the swirl in the flow. The liquid water can reach and rest against an inner side of the outer wall or outer tube of the annular channel. The partially radial widening of the radially outer wall of the annular channel can promote the conduction of water along the inner side of the outer wall of the annular channel, particularly in the axial direction.

[0014] According to one embodiment, the radial widening of the radially outer wall of the annular channel can be provided at least in sections around a circumference of the annular channel. In this embodiment, the radial widening can have recesses that can be designed as incisions. The incisions can be provided in a predetermined number. The incisions can form grooves open toward the radially inner side of the annular channel. The inwardly open grooves can widen radially outward toward the outlet side.

[0015] According to one embodiment, the radial widening of the radially outer wall of the annular channel can comprise recesses in the radially outer wall of the annular channel, which recesses extend at least partially in a longitudinal direction of the annular channel. The recesses can extend parallel to the longitudinal direction of the annular channel. Alternatively, the recesses can extend along a helical or curved shape with respect to the longitudinal direction of the annular channel. Furthermore, the recesses can extend skewed with respect to the longitudinal direction of the annular channel.

[0016] According to one embodiment, the recesses can be distributed around the circumference of the annular channel. The recesses can be distributed evenly around the circumference of the annular channel. Alternatively, the recesses can be distributed unevenly around the circumference of the annular channel, so that at a position where the collection of the separated water is desired, more recesses are provided relative to the circumference of the annular channel than in areas where the separation of water is not desired or expected.

[0017] According to one embodiment, the radial widening of the radially outer wall of the annular channel can comprise a widening around the entire circumference of the annular channel. In this case, the outer wall of the annular channel can be conical. Alternatively, the radially outer wall of the annular channel can be designed with a predetermined function relative to the axial length of the annular channel. In both cases, the radial widening of the radially outer wall causes an enlargement of a cross-sectional area within the annular channel toward the outlet side of the annular channel.

[0018] According to one embodiment, the radial widening can extend from a region between the inlet side and the outlet side to the outlet side of the annular channel. In particular, the radially outer wall of the annular channel can be formed with a constant diameter over a predetermined section, and the widening can adjoin the section with a constant diameter. The region between the inlet side and the outlet side of the annular channel, where the widening towards the outlet side has its starting point, is freely selectable and is selected such that optimal water separation can be achieved.

[0019] According to one embodiment, a radially inner wall of the annular channel can be substantially cylindrical with a diameter that remains substantially constant between the inlet and outlet sides of the annular channel. This embodiment, in conjunction with the radial expansion, results in a cross-sectional area that increases toward the outlet side of the annular channel. The increased cross-sectional area in the direction of flow of the gas mixture can influence the flow and, in particular, the flow velocity of the gas mixture, thus improving water separation.

[0020] According to one embodiment, a cross-sectional area of ​​the annular channel can be larger in the region in which the widening is provided than in the region in which the widening is not provided.

[0021] According to one embodiment, the cross-sectional area of ​​the annular channel in the region in which the widening is provided can also increase in the direction of the outlet end of the annular channel.

[0022] According to one embodiment, the widened portion in the region of the outlet side of the annular channel can open into a water drainage arrangement, which is configured to drain water moving along the wall of the widened portion to a water outlet arrangement. The water drainage arrangement can be designed as an annular channel at the outlet end, which can be connected to a line for draining the water entering the annular channel. The water drainage arrangement can be designed as at least one opening in or on the outlet side of the annular channel, into which the water can enter. The water outlet arrangement can have a container for receiving the water drained from the water drainage arrangement. The water outlet arrangement can further have a line by means of which the water drained by the water drainage arrangement can be drained away, in particular into the environment.

[0023] The water drainage arrangement may include an annular gap provided on a radially oriented wall on the outlet side of the annular channel. The water drainage arrangement may include an opening formed in a radially oriented wall on the outlet side of the annular channel. At least one opening may be provided in a lower region on the outlet side of the annular channel, taking gravity into account.

[0024] According to one embodiment, at least one water guiding arrangement can be provided in the annular channel, which has at least one helically formed recess in the outer wall of the annular channel. Taking into account the swirl applied to the flowing gas mixture, the direction of the helical shape of the recess can be determined according to this direction. The recess in the outer wall of the annular channel can be designed such that the liquid water subjected to the swirl flows along the recesses towards the water discharge arrangement on the outlet side of the annular channel. The helical shape can promote the expedient flow of the water if the helical direction corresponds to the direction of rotation of the gas mixture flowing in the annular channel. At the end of the helical recess, an opening can be provided which is connected to the water outlet arrangement.Alternatively, a plurality of recesses may be provided extending helically along the outer wall of the annular channel. In this case, a plurality of openings may be provided at the corresponding ends of the recesses, which may be connected to the water outlet arrangement.

[0025] According to a further aspect, a fuel cell arrangement is specified with a blower that has one or more of the aforementioned features, wherein the blower is connected to the fuel cell arrangement for recirculating a gas mixture used for operating the fuel cell arrangement. The blower can be connected to a fuel cell module via a line arrangement in the fuel cell arrangement. The blower can be provided for recirculating hydrogen-containing gas for the fuel cell arrangement. In particular, the recirculation of the hydrogen-containing gas can be designed for the anode side of the fuel cell arrangement. The blower can be controlled, if required, via a control device, wherein an operating state of the fuel cell arrangement can be taken into account.The fuel cell arrangement may also comprise a plurality of fans of the type described above, which are integrated into the fuel cell arrangement by means of lines.

[0026] The blower and the fuel cell assembly can be used in a mobile application. In particular, the blower and the fuel cell assembly can be used in an electrically powered vehicle, wherein the electrical power can be generated by the fuel cell assembly. Alternatively, the fuel cell assembly with the blower can be used in a stationary application. Alternatively, the blower can be used to provide a gas flow in other areas. In particular, the blower can be used to achieve a flow through the cathode side of the fuel cell assembly. Short description of the characters Fig. 1 shows an embodiment of a blower in a cross-sectional view; Fig. 2 shows a blower in a further embodiment in a cross-sectional view; and Fig. 3 shows an installation position of the fan in one embodiment. Detailed description of embodiments

[0027] Embodiments are described below with reference to the accompanying drawings.

[0028] Fig. Figure 1 shows a blower in one embodiment in a cross-sectional view. The basic structure of the blower is described below based on Fig. 1. As shown in the cross-sectional view of Fig. 1, the blower 1 has a main housing 2. The main housing 2 forms the outer circumference of a main section of the blower 1 and is cylindrical in the present embodiment. Arranged radially inside the main housing 2 is a drive motor which has a radially outer stator 8, a radially inner rotor 9 and a motor shaft 7 connected to the rotor 9. The stator 8 is connected to the main housing 2 in a rotationally fixed manner. The rotor 9 is connected to the rotatable motor shaft 7 so that the rotor 9 can rotate together with the motor shaft 7. The motor shaft 7 is rotatably mounted on both sides via bearings 11, 12. In the present embodiment, the rotor 9 is designed as a permanent magnet element. When energized, the stator 8 generates a rotating magnetic field so that the rotor 9 rotates together with the motor shaft 7 when energized.

[0029] On the left side in Fig. 1, the main housing 2 has an outlet housing 4. The outlet housing 4 has a passage in the center through which the motor shaft 7 passes. In the area of ​​the outlet housing 4, a fan impeller 5 is connected to the motor shaft 7. Rotation of the motor shaft 7 causes rotation of the fan impeller 5. The outlet housing 4 has an outlet volute radially outside the outlet housing 4, which has a circumferentially variable diameter and is open towards the fan impeller 5. A housing flange 6 is attached to the outlet housing 4, which has a passage in the center into which the motor shaft 7 projects.

[0030] The fan impeller 5 has blades that are designed with a predetermined shape to achieve the pumping function. The inside of the housing flange 6 and the inside of the outlet housing 4 are adapted to the contour of the fan impeller 5 in the radial region where the fan impeller 5 is provided. Radially outside the fan impeller 5 is an annular gap that is open to the volute within the outlet housing 4. On the side of the fan impeller 5 facing away from the rotor 9, the bearing 11 for supporting the motor shaft 7 is provided. In the present embodiment, the bearing 11 comprises a set of rolling bearings, the outer ring of which is inserted into the housing flange and the inner ring of which is mounted on the motor shaft 7. The housing flange 6 has a cover (not explained in detail) on the side of the bearing 11 facing away from the rotor.

[0031] An annular channel 10 is provided radially between the stator 8 and the rotor 9. A radial inner wall of the annular channel 10 is formed by an outer circumference of the rotor 9. The radial outer wall of the annular channel 10 is formed by an outer tube. The outer tube has a diameter that is larger than the diameter of the outer circumference of the rotor 9. The stator 8 is located radially outside the outer tube. This forms the annular channel 10, through which a fluid can flow. The annular channel 10 opens on the left side into Fig. 1 in the area of ​​the fan impeller 5. On the right side of the annular channel 10 there is a flow guide device described below.

[0032] On the right side in Fig. 1, the blower 1 has an inlet housing 3. The inlet housing 3 is cylindrical and is inserted into the main housing 2 with a section. A sealing element is provided between the inlet housing 3 and the main housing 2. The inlet housing 3 is screwed to the main housing 2 via a mounting flange. On the right side in Fig. 1, the inlet housing 3 has an inlet flange 13. The inlet flange 13 serves to connect to a pipe of the fuel cell assembly.

[0033] The flow control device is explained below. As described in Fig. 1, the flow guide device is in the form of a guide grid 14 on the in Fig. 1 right-hand section of the annular channel 10. The guide vane 14 has an arrangement of guide vanes distributed around a circumference of the flow guiding device. The guide vanes are provided in particular in the area that is open towards the annular channel 10. The guide vane 14 can be flowed through through a passage in the inlet housing 3 in the direction of the annular channel 10. The guide vane 14 has a passage in the middle through which a section of the motor shaft 7 projects. In the area in which the guide vane 14 is provided, the motor shaft 7 is supported relative to the inlet housing 3 and thus relative to the main housing 2. On the side of the guide vane 14 facing away from the rotor 9, a flow insert 15 in the form of an axially symmetrical flow body is provided. The flow insert 15 has a dome or calotte shape. The outer diameter of the flow insert 15 is smaller than the diameter of the outer tube of the annular channel 10.The flow insert 15 extends axially into a region of the inlet housing 3 where a constriction is provided. The flow insert 15 has a flow-optimized outer contour with respect to the flow from the inlet housing 3.

[0034] With the structure described above, a flow through the fan 1 from the inlet side, which is on the right side in Fig. 1, to the exit side, which is on the left side in the Fig. 1 is possible. In particular, the flow into the inlet housing 3 runs through a widening annular gap between the flow insert 15 and the inner wall of the inlet housing 3, through the guide vane 14, into the annular channel 10 to the fan impeller 5, wherein the gas mixture is driven into the outlet volute in the outlet housing 4 by the rotation of the fan impeller 5.

[0035] The concept of the blower 1 shown is explained in more detail below.

[0036] The arrangement of vanes or blades in the guide vane 14 causes the gas mixture flowing through the guide vane 14 to be deflected in a circumferential direction as it flows through. For this purpose, the guide vane 14 has vanes or blades that are inclined and profiled with respect to the longitudinal axis of the annular channel 10. This causes a gas mixture entering the guide vane 14 essentially in a straight line to exit the guide vane 14 with a velocity component in the circumferential direction. This effect is achieved when the fan impeller 5 is operated, so that the gas mixture is conveyed by the fan 1. In addition, this effect also occurs when the gas mixture is conveyed through the fan 1, and in particular through the guide vane 14 and the annular channel 10, without rotation of the fan impeller 5.

[0037] Particularly in mobile applications, such as vehicle propulsion systems, icing of elements of the fuel cell assembly, and in particular of the blower 1 for recirculating the gas mixture, must be avoided. By efficiently removing the water from the blower 1, such ice formation can be easily prevented, for example, when the vehicle is parked for an extended period at low temperatures.

[0038] Due to the rotation of the gas mixture flow within the annular channel 10, an outward centrifugal force is exerted on the components of the gas mixture. If liquid water droplets are present in the gas mixture, the swirl or rotation of the gas mixture flow causes the liquid water droplets to move radially outward, so that they reach the inside of the radially outer wall of the annular channel 10. Due to the axial component of the gas mixture flow within the annular channel 10, the water droplets adhering to the inside of the outer wall of the annular channel 10 are moved axially toward the outlet side.

[0039] According to the basic concept of the present embodiment, the annular channel 10 has a water guiding arrangement 16. The water guiding arrangement 16 is located in the Fig. 1, in the area of ​​the left side of the annular channel 10, which corresponds to the area of ​​the outlet side. In the present embodiment, the water guiding arrangement 16 is formed by widening an axial region of the radially outer wall of the annular channel. Since the diameter of the radially inner wall of the annular channel 10 is constant over the entire length in the present embodiment, the cross-sectional area of ​​the annular channel 10 increases in the region where the widening is provided. Fig. 1, the predominant axial section of the annular channel 10 is formed with a constant cross-sectional area. Only a part of the axial length of the annular channel 10, for example less than 50% or an area of ​​approximately 25%, is provided with the widening. In this area, in which the widening of the water guiding arrangement 16 is provided, the diameter of the radially outer wall of the annular channel 10 increases in the direction of the outlet side. This design enables water droplets adhering to the radially outer wall of the annular channel 10 and moving towards the outlet side to be moved more reliably and quickly to the outlet side due to the inclination in the area of ​​the widening with respect to the axial direction of the annular channel 10 and the radially acting centrifugal force.

[0040] A water discharge arrangement 17 is provided on the outlet side of the water guide arrangement 16. In the present embodiment, the water discharge arrangement 17 is provided as an annular gap, which is provided in the area where the diameter of the annular channel 10 is largest due to the widening. The water moving along the widening can thus directly enter the water discharge arrangement 17 in the form of the annular gap. The annular gap of the water discharge arrangement 17 is provided in the present embodiment with a Fig. 1, through which the separated water can be discharged accordingly. In the present embodiment, the separated water is collected in a container (not shown). In an alternative embodiment, the water can be discharged into the environment, provided this complies with environmental regulations.

[0041] In the following, a further embodiment is described with reference to Fig. 2. It should be noted that the following embodiment is an alternative or a supplement to the embodiment of Fig. 1. As in Fig. 2, the radially outer wall of the annular channel 10 has a helical recess which forms a water guiding arrangement 18. The helical recess is designed with a direction of rotation which corresponds to the direction of rotation of the swirl imposed on the gas mixture. As described above, the swirl applied to the gas mixture flowing through the annular channel 10 causes water droplets contained in the gas mixture to move radially outward to the radially outer wall of the channel 10 and rest there. Due to the rotating flow within the annular channel 10 around the central axis of the fan 1, the water droplets on the inner wall of the annular channel 10 also move along a helical trajectory.The recesses of the water guiding arrangement 18 provided in this embodiment cause isolated drops to collect on the wall and combine to form larger drops, the movement of which along the surface is simplified.

[0042] The embodiment of Fig. 2 has, in a similar manner to the embodiment of Fig. 1 has a water drainage arrangement 17, which is designed as an opening or annular gap into which the water to be drained can enter. Likewise, the embodiment of Fig. 2 in a similar manner to the embodiment of Fig. 1 one in Fig. 2 has a water outlet arrangement not shown, through which the drained water can be discharged.

[0043] In an alternative embodiment, the helically formed recess of the water guiding arrangement 18 of the embodiment of Fig. 2 with the widening of the water guiding arrangement 16 of the embodiment of Fig. 1. In this case, the advantages of both concepts are combined, resulting in improved water separation within blower 1.

[0044] In the following, a further embodiment is described with reference to Fig. 3. As described in Fig. As shown in Figure 3, the fan 1 is arranged tilted relative to the horizontal orientation. Fig. The arrangement shown in Figure 3 represents the installation position of the fan 1 within the application when the system on which the fuel cell assembly is mounted, such as an automobile, is oriented horizontally. As shown in Fig. 3, the water outlet arrangement 19 is arranged at the lower part of the annular channel 10. Due to the inclined installation position according to Fig.3, the outlet area of ​​the annular channel 10 is located lower than the inlet area. This embodiment prevents water from accumulating at the bottom of the annular channel when the fan 1 is horizontally aligned, particularly when the fan is at a standstill. Furthermore, the separation of water into the water outlet arrangement 19 is further promoted during operation of the fan 1.

[0045] It should be noted that the above-mentioned concepts, which were described separately on the basis of the figures, can be combined with each other.

[0046] The blower 1 of the present embodiments is used in a fuel cell assembly in which hydrogen-containing gas is circulated and reacts electrochemically to generate electrical energy. In particular, the blower 1 described here is used to purge an anode region of a fuel cell assembly to ensure a predetermined composition of the gas mixture present in the anode region.

[0047] Several of the above-described blowers 1 can be used in the fuel cell assembly. Furthermore, the fuel cell assembly generally comprises a control device that, among other things, controls the operation of the blower 1. This includes controlling a speed of the blower 1, with which the blower power can be adjusted. Furthermore, the operating state of the fuel cell assembly is used to determine whether or not operation of the blower 1 is required. In the event that the blower 1 is not operating, the gas mixture can easily be passed through the blower 1 due to the structure of the blower as a media gap motor.Due to the above-described structure of the blower 1 and in particular of the flow guide device with the guide grille 14, the separation function for separating water is brought about even when the blower 1 is not in operation by the flow through the blower 1, since the guide grille 14 imposes the swirl on the gas flow.

[0048] The blower described above is particularly applicable to the fuel cell arrangement described above. However, the blower is also applicable to other fuel cell arrangements, provided water separation is appropriate. Reference symbol 1 fan 2 main housings 3 inlet housing 4 Outlet housing 5 Fan impeller 6 Housing flange 7 Motor shaft 8 Stator 9 Rotor 10 ring canal 11 camps 12 camps 13 Inlet flange 14 guide vanes (flow control device) 15 Flow installation 16 Water guidance arrangement 17 Water drainage arrangement 18 Water guidance arrangement 19 Water outlet arrangement 20 entrance channel

Claims

[1] Blower (1) for a fuel cell arrangement for recirculating a gas mixture used for operating the fuel cell arrangement, comprising a drive motor (7, 8, 9) which has a rotor (9) coupled to a motor shaft (7) and a stator (8) arranged radially outside the rotor (9), wherein an annular channel (10) is provided radially between the rotor (9) and the stator (8) for conveying the gas mixture from an inlet side to an outlet side of the annular channel (10), wherein in the region of the outlet side of the annular channel (10) a blower impeller (5) coupled to the motor shaft (7) is provided in order to convey the gas mixture from the inlet side to the outlet side of the annular channel (10) during rotation, further comprising a flow guide device (14) which is provided in the region of the inlet side of the annular channel (10) and is designed to to impart a swirl in the circumferential direction of the annular channel (10) to the gas mixture,further comprising an arrangement for separating water from the gas mixture, wherein the arrangement for separating water from the gas mixture has an at least partially radial widening of the radially outer wall of the annular channel (10). [2] Blower (1) according to claim 1, characterized by that the radial widening of the radially outer wall of the annular channel (10) around a circumference of the annular channel (10) is provided at least in sections. [3] Blower (1) according to claim 1 or 2, characterized by that the radial widening of the radially outer wall of the annular channel (10) has depressions in the radially outer wall of the annular channel (10) which extend at least in sections in a longitudinal direction of the annular channel (10). [4] Blower (1) according to one of the preceding claims, characterized by that the recesses are distributed around the circumference of the annular channel (10). [5] Blower (1) according to one of the preceding claims, characterized by, the radial widening of the radially outer wall of the annular channel (10) has a widening around the entire circumference of the annular channel (10). [6] Blower (1) according to one of the preceding claims, characterized by that the radial widening extends from a region between the inlet side and the outlet side to the outlet side of the annular channel (10). [7] Blower (1) according to one of the preceding claims, characterized by that a radially inner wall of the annular channel (10) is substantially cylindrical with a diameter that is substantially constant between the inlet side and the outlet side of the annular channel (10). [8] Blower (1) according to one of the preceding claims, characterized by that a cross-sectional area of the annular channel (10) in the region in which the widening is provided is larger than in the region in which the widening is not provided. [9] Blower (1) according to one of the preceding claims, characterized by that a cross-sectional area of the annular channel (10) in the region in which the widening is provided increases in the direction of the outlet end of the annular channel (10). [10] Blower (1) according to one of the preceding claims, characterized by that the widening in the region of the outlet side of the annular channel (10) opens into a water discharge arrangement (17) which is designed to discharge water flowing along the wall of the widening to a water outlet arrangement (19). [11] Blower (1) according to one of the preceding claims, characterized by that at least one water guiding arrangement (18) is provided in the annular channel (10), which has at least one recess formed in a screw shape in the outer wall of the annular channel (10). [12] Fuel cell arrangement with a blower (1) according to one of the preceding claims, which is connected to the fuel cell arrangement for recirculating a gas mixture used for the operation of the fuel cell arrangement.

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