A water separator unit for fuel cell system

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The single baffle water separator unit addresses inefficiencies in fuel cell systems by optimizing water separation with a swirl core outlet, achieving efficient hydrogen recirculation and cost-effective manufacturing.

WO2026158900A1PCT designated stage Publication Date: 2026-07-30ROBERT BOSCH GMBH +1

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Patent Information

Authority / Receiving Office: WO · WO
Patent Type: Applications
Current Assignee / Owner: ROBERT BOSCH GMBH
Filing Date: 2025-12-30
Publication Date: 2026-07-30

AI Technical Summary

Technical Problem

Existing water-gas separators for fuel cell systems face inefficiencies in separating water from hydrogen and nitrogen mixtures, leading to pressure losses and complex manufacturing processes due to multiple baffles.

Method used

A single baffle design in a water separator unit with a swirl core outlet and optimized internal geometry to enhance water separation by centrifugal force, reducing pressure losses and manufacturing complexity.

Benefits of technology

The single baffle design effectively separates water from hydrogen and nitrogen, maintaining optimal pressure and reducing manufacturing costs while ensuring efficient hydrogen recirculation.

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Abstract

The water separator unit (100) comprises a container (116) comprising a base (112) with a drain port (114), the container (116) comprises an open end opposite to the base (112). The water separator unit (100) further comprises a cover (120) positioned over the open end of the container (116). The cover (120) comprises an inlet (106) in the side wall (118) to receive a fluid, and an outlet (102) in the plate (104) to discharge gases separated from the fluid, characterized in that, the water separator unit (100) comprises a baffle (110) formed in the cover (120) and positioned in a direction of incoming fluid flow through the inlet (106). The baffle (110) is positioned in such a manner that flow of the fluid received through the inlet (106) is obstructed and diverted towards side walls (118) of the cover (120).

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Description

Patent application Number: 202541006047 RNR: 418129Title of the invention: A WATER SEPARATOR UNIT FOR FUEL CELL SYSTEMField of the invention:

[0001] The present invention relates to a water separator unit for fuel cell system.Background of the invention:

[0002] According to a prior art CN117174953, water-gas separator for anode end of fuel cell is disclosed. The prior art relates to the technical field of fuel cells, in particular to a water-gas separator for an anode end of a fuel cell. Comprising a separator shell and a separator cover body, an inner cavity of the separator shell is of a cuboid hollow structure, and the separator cover body is arranged at the top of the separator shell; an inlet of the air inlet channel is formed in one side of the separator shell, and an outlet of the air inlet channel is formed in the top of the separator cover body; the baffle plate is arranged on a water vapor circulation path between the inlet of the air inlet channel and the outlet of the air inlet channel; the water leakage plate is arranged below the baffle plate, and the exhaust and drainage valve is arranged at the bottom of the separator shell and is matched with the position of the water leakage plate, so that the effects of efficiently separating the liquid water in the tail exhaust of the fuel cell and realizing hydrogen circulation are achieved.Brief description of the accompanying drawings:

[0003] An embodiment of the disclosure is described with reference to the following accompanying drawings,

[0004] Fig. 1 illustrates a schematic of a water separator unit for a fuel cell system in a first configuration, according to an embodiment of the present invention;

[0005] Fig. 2 illustrates a schematic of a second configuration of the water separator unit for the fuel cell system, according to an embodiment of the present invention, andPatent application Number: 202541006047 RNR: 418129

[0006] Fig. 3 illustrates a schematic of a third configuration of the water separator unit for the fuel cell system, according to an embodiment of the present invention.Detailed description of the embodiments:

[0007] Fig. 1 illustrates a schematic of a water separator unit for a fuel cell system in a first configuration, according to an embodiment of the present invention. The water separator unit 100 comprises a container 116 comprising a base 112 with a drain port 114, the container 116 comprises an open end opposite to the base 112. The water separator unit 100 further comprises a cover 120 positioned over the open end of the container 116. The cover 120 comprises a plate 104 with side walls 118 extending from periphery of the plate 104 and forms a cavity therewith. The cover 120 comprises an inlet 106 in the side wall 118 to receive a fluid, and an outlet 102 in the plate 104 to discharge gases separated from the fluid, characterized in that, the water separator unit 100 comprises a baffle (also known as rib) 110 formed in the cover 120 and positioned in a direction of incoming fluid flow through the inlet 106. The baffle 110 is positioned in such a manner that flow of the fluid received through the inlet 106 is obstructed and diverted towards side walls 118 of the cover 120. Only one / single baffle 110 with a specific design is provided instead of multiple baffles 110 to improve the separation efficiency. The outlet 102 comprises a tube 122 which protrudes inside the cavity.

[0008] In Fig. 1, a first view 124 shows a side cross-sectional view of the water separator unit 100 and a second view 126 shows a top cross-section view of the water separator unit 100. With reference to first view 124, it is clear that the water separator unit 100 is made of two parts, a first part is the cover 120 mounted or fixed on top of the second part, i.e., the container 116. The cover 120 comprises the plate 104, the side walls 118 and the inlet 106. Similarly, the container 116 comprises the base 112, the drain port 114 and the step profile 108.

[0009] With reference to second view 126, the fluid flow is shown from the inlet 106 and within the chamber formed by the cover 120 and the container 116 usingPatent application Number: 202541006047 RNR: 418129directional arrows. Externally, the inlet 106 is in fluid communication with the anode stack outlet of the fuel cell system.

[0010] According to an embodiment of the present invention, the inlet 106 is possible to be positioned at the side wall 118 of the cover 120 at various possible orientations (in terms of height, too). The outlet 102 is designed to be positioned at the plate 104 (or the top of the cover 120), precisely at the swirl core. The fluid is received in the cavity through the inlet 106. The baffle 110, one in number, is arranged to obstruct the flow of the fluid, and additionally to divert the fluid flow to the internal surface of the side walls 118 of the cover 120.

[0011] In the Fig. 1, the first configuration of the water separator unit 100 is illustrated where the base 112 of the container 116 is shaped like a funnel towards the drain port 114. In an embodiment, the drain port 114 is at the center of the base 112. The drain port 114 is optionally provided with a filter and / or a drain plug. The base 112 is funnel shaped towards the drain port 114 to drain the collected water at all vehicle inclinations. The base 112 of the container 116 is sloped towards the drain port 114. This enhances water gathering area and smooth transition of flow patterns.

[0012] According to an embodiment of the present invention, the base 112 of the container 116 starts after a step profile 108. The baffle 110 is positioned / located above the step profile 108. The step profile 108 is an extended region of the base 112 which is underneath and after the opening of the inlet 106. The step profile 108 provided in the container 116 is designed in such a way that not to impact the fluid flow generation pattern. The step profile 108 also enhances the water collection area and smooth transition of flow pattern.

[0013] According to the present invention, a working of the water separator unit 100 is explained. The water separator unit 100 typically removes water from the Hydrogen-Nitrogen mixture to enhance the recirculation of hydrogen back to thePatent application Number: 202541006047 RNR: 418129fuel cell system (not shown). For the removal of water from the mixture, a combined method of swirl generation and diversion of flow with the baffle 110 or (rib) at the inlet 106 is employed. The inlet 106 of the water separator unit 100 is connected with the anode stack outlet of the fuel cell system. The exhaust fluid from stack anode outlet consisting of DI water and gases (mainly Nitrogen and Hydrogen) enters the inlet 106 of the cover 120. The fluid received through the outlet is mixture of hydrogen, water and nitrogen and others (the anode gas is mixture of Hydrogen and Nitrogen gases majorly). The hydrogen is to be extracted from the fluid and is to be recirculated back to the fuel cell system. The water separator unit 100 separates the hydrogen from the fluid. The fluid enters the water separator unit 100 through the inlet 106. On entering and exiting the inlet 106, the fluid flow gets diverted to the side walls 118 of the cover 120 by the baffle 110 placed along the flow of the stream, i.e., the fluid strikes the baffle 110 placed in the flow path, which directs or diverts the fluid to the side wall 118 of the cover 120. The internal surface or the side wall 118 of the cover 120 is curved and designed to create a swirl flow inside the cavity of the cover 120. The fluid flow forms streamlines over the surface of the baffle 110, due to which the water droplets / particles in the fluid gets trapped and is stuck on the inner side walls 118 of the cover 120.

[0014] There is a possibility of pressure drop in gas flow during separation process which affects the overall system efficiency. To minimize the pressure losses, the design of baffle 110 and the position of the outlet 102 in the water separator unit 100 plays a maj or role. The fluid flow then is made to have a swirling motion around the outlet 102 due to the construction of the inner geometry of the cover 120 and is made to direct towards the outlet 102. During the swirl flow, the water particles present in the fluid sticks to the side wall 118 due to centrifugal force and separates from the other gaseous particles. The gases swirls and passes through the outlet 102 provided in the plate 104 of the cover 120. The water film flow is detached from the outlet 102 to prevent the escape of water to re-circulation unit / path. This is achieved by protrusion in the outlet 102 to retain the collected water films / droplets. The protrusion prevents any passage of the water particles to go through the outletPatent application Number: 202541006047 RNR: 418129102. The water is accumulated in the base 112 of the container 116, and is discharged through the drain port 114.

[0015] According to an embodiment of the present invention, the outlet 102 is provisioned at swirl core of the cover 120. The side wall 118 of the cover 120 and internal surface of the container 116 are curved to aid in flow of the fluid. Further, the baffle 110 originates from the side wall 118 of the cover 120 and curves / bends towards flow direction of fluid received from the inlet 106. The baffle 110 is at a distance from an opening of the inlet 106 and covers the opening of the inlet 106 either completely or at least partially to direct flow of the incoming fluid towards the internal side wall 118. In brief, the baffle 110 either partially or completely covers the opening of the inlet 106.

[0016] Further, a central axis of the outlet 102 and the drain port 114 may or may not be coinciding. In the first view 124, the central axis of the outlet 102 is offset from the central axis of the drain port 114. However, in the second view 126, the central axis of both the outlet 102 and the drain port 114 are coinciding. The first view 124 and the second view 126 shows the first configuration of the water separator unit 100 but with different positioning of the outlet 102 and the drain port 114.

[0017] Fig. 2 illustrates a schematic of a second configuration of the water separator unit for the fuel cell system, according to an embodiment of the present invention. The drain port 114 is offset from the center of the base 112. The base 112 is then sloped to the offset position of the drain port 114. The angle of slope is decided as per requirement and not limited to what is shown in Fig. 2. The base 112 is tilted / sloped towards the drain port 114 at a specific angle to drain the collected water at all inclinations of a vehicle in which it is implemented. The base 112 of the container 116 is slanted more from one side than the other.Patent application Number: 202541006047 RNR: 418129

[0018] In Fig. 2, a third view 202 shows a side cross-section view of the water separator unit 100 in the second configuration. Similarly, a fourth view 204 shows a top cross-section view of the water separator unit 100 in the second configuration. The offset position of the drain port 114 and the outlet 102 are clearly visible.

[0019] According to an embodiment of the present invention, an internal geometry of cover 120 is any one selected from a group comprising oblong design, a square design, a rectangular design, a cylindrical design, with smooth formation of curves. According to the present invention, the water separator unit 100 is appliable to be used on stationary fuel cell systems of movable fuel cell systems.

[0020] According to an embodiment of the present invention, only one baffle 110 along the flow direction of fluid from the inlet 106 is provided. The baffle 110 near the inlet 106 is positioned in line with fluid flow to direct the fluid towards the inner side wall 118. The outlet 102 is placed at the swirl core aiding better film collection and sending hydrogen for re-circulation. The position of the outlet 102 enables the continuous flow swirl action, and the surface area of the droplet interaction is improved causing higher wall film formations. The gases in the fluid are allowed to cover larger surface area to enhance droplet collection and to reduce the gas energy which prevents the film breakage. The container 116 is sloped to enhance the collected water to the drain port 114.

[0021] Similar to Fig. 1, in Fig. 2, the central axis of the outlet 102 and the drain port 114 are offset and is shown in both the third view 202 and the fourth view 204.

[0022] Fig. 3 illustrates a schematic of a third configuration of the water separator unit for the fuel cell system, according to an embodiment of the present invention. In the third configuration, the container 116 is made well-type (flat collection zone) to drain large volume of water through the drain port 114. A fifth view 302 illustrates side-cross section of the water separator unit 100 with third configuration and a sixth view 304 illustrates top cross-section of the water separator unit 100.Patent application Number: 202541006047 RNR: 418129The well-type design reduces the interactions of collected water and gases. The drain port 114 in the container 116 is designed far away from the inlet 106.

[0023] In Fig. 3, the fifth view 302 shows the offset between the central axis of the drain 102 and the drain port 114. However, in the sixth view 304 the central axis of the outlet 102 and the drain port 114 is same, i.e., there is no offset. Thus, within different configurations of the water separator unit 100, the possibility of different positioning of the outlet 102 and the drain port 114 is illustrated and explained.

[0024] According to an embodiment of the present invention, the container 116 of the water separator unit 100 is any one selectable from three difference configurations comprising a first configuration, a second configuration and a third configuration.

[0025] According to an embodiment of the present invention, the water separator unit 100 comprises the container 116 comprising the base 112 with the drain port 114, the container 116 comprises an open end opposite to the base 112. The water separator unit 100 further comprises the cover 120 positioned over the open end of the container 116. The cover 120 comprises the plate 104 with side walls 118 extending from periphery of the plate 104 and forms the cavity therewith. The cover 120 comprises the inlet 106 in the side wall 118 to receive the fluid, and the outlet 102 in the plate 104 to discharge gases separated from the fluid, characterized in that, the drain port 114 is provided either at center of the base 112 or offset from the center of the base 112. In addition, the surface of the base 112 is slanted / slopped / inclined towards the drain port 114 irrespective of the position of the drain port 114.

[0026] According to an embodiment of the present invention, a diameter or opening dimension of the inlet 106 and the outlet 102 of the cover 120 is varied as per requirement since it has a direct impact on inlet velocity and suction effect (from Jet pump and recirculation blower of the fuel cell system) respectively. A height ofPatent application Number: 202541006047 RNR: 418129the cover 120 is also varied as per the required application and requirements. The position of drain port 114 is at the bottom of the container 116, and is either at the exact center or any position at the bottom but not below the cover / container inlet but not just below the inlet 106 and preferably away from the inlet 106. A volume of the cover 120 is increased for reducing the internal velocity of recirculation fluid / droplet and the surface area of side wall 118 of the cover 120 is increased for better water droplet collection. The swirl intensity is reduced due to the longer swirl path. A section of the outlet 102 is reduced due to the detached cylindrical protrusion from the plate 104 of the cover 120. A wider flow path is achieved to reduce the flow acceleration to avoid the breakage of water film. The baffle 110 is placed closer to the inner side wall 118 of the cover 120.

[0027] According to an embodiment of the present invention, a single baffle 110 based water separator unit 100 for optimal water separation and collection in fuel cell system is disclosed. The separation of water from the gases (predominantly Hydrogen) coming from stack anode outlet is fulfilled. Overall pressure losses are maintained at an optimum range whilst achieving this separation. The present invention facilitates smooth draining of collected water into the ambient with different configurations of the container 116.

[0028] The water separator unit 100 enhances the separation of water from gases by the provision of only one baffle 110 (rib) at the inlet 106 and the position of outlet 102 at the swirl core of the cover 120. The position of the one baffle 110 is designed such a way to cover the complete inlet flow path or at least partially covering to direct the flow towards the side wall 118 of the cover 120. The water separator unit 100 eliminates multiple baffles 110 and brings about cost savings and reduce manufacturing complexity. The design of the container 116 is in such a way that it enhances smooth collection of water. The step profile 108 is the extended region provided in the container 116 below the opening of the inlet 106 to avoid movement of gas into the base 112.Patent application Number: 202541006047 RNR: 418129

[0029] It should be understood that the embodiments explained in the description above are only illustrative and do not limit the scope of this invention. Many such embodiments and other modifications and changes in the embodiment explained in the description are envisaged. The scope of the invention is only limited by the scope of the claims.

Claims

Patent application Number: 202541006047 RNR: 418129We claim:

1. A water separator unit (100) for a fuel cell system, said water separator unit (100) comprises:a container (116) comprising a base (112) with a drain port (114), said container (116) comprises an open end which is opposite to said base (112), anda cover (120) positioned over said open end of said container (116), said cover (120) comprises a plate (104) with side walls (118) extending from periphery of said plate (104) to form a cavity therewith, said cover (120) comprises an inlet (106) in said side wall (118) to receive a fluid, and an outlet (102) in said plate (104), characterized in that,a baffle (110) formed in said cover (120) and positioned in a direction of flow of fluid through said inlet (106), said baffle (110) is positioned in such a manner that flow of said fluid through said inlet (106) is obstructed and diverted towards side walls (118) of said cover (120).

2. The water separator unit (100) as claimed in claim 1, wherein said base (112) of said container (116) starts after a step profile (108), and said baffle (110) is positioned above said step profile (108).

3. The water separator unit (100) as claimed in claim 1, wherein said outlet (102) is provisioned at swirl core of said cover (120).

4. The water separator unit (100) as claimed in claim 1, wherein an internal surface of said cover (120) and said container (116) is curved to aid in flow of said fluid.

5. The water separator unit (100) as claimed in claim 1, wherein said baffle (110) originates from said side wall (118) of said cover (120) and curves towards flow direction of fluid received from said inlet (106), and said bafflePatent application Number: 202541006047 RNR: 418129(110) is at a distance from an opening of said inlet (106) and covers said opening of said inlet (106) either completely or at least partially to direct flow of said fluid towards said internal side wall (118).

6. The water separator unit (100) as claimed in claim 1, wherein said base (112) of said container (116) is sloped towards said drain port (114).

7. The water separator unit (100) as claimed in claim 1, wherein said drain port (114) is at a center of said base (112).

8. The water separator unit (100) as claimed in claim 1, wherein said drain port (114) is offset from a center of said base (112).

9. The water separator unit (100) as claimed in claim 1, wherein an internal geometry of said cover 120 is any one selected from a group comprising oblong design, a square design, a rectangular design, a cylindrical design, with smooth formation of curves.

10. The water separator unit (100) as claimed in claim 1, wherein said outlet (102) comprises a tube (122) which protrudes inside said cavity of said cover (120).Dated 30 December 2025 (Digitally signed)Siddharth Karkhanis (IN / PA- 1195) On-behalf of the Applicants