Apparatus for diluting hydrogen concentration in a fuel cell exhaust system

Abstract

An apparatus for diluting hydrogen concentration in a fuel cell exhaust system is provided. The apparatus includes a fuel cell exhaust line configured to receive a gas stream from a connected fuel cell and including a hydrogen stream. The apparatus also includes a mixing chamber disposed to receive the hydrogen stream and configured to mix an air stream with the hydrogen stream. The mixing chamber includes a mixing grid including at least one tab feature configured to alter a flow direction of at least a portion of one of the hydrogen stream and the air stream and to create a turbulent flow region within the mixing chamber.

Description

Technical Field

[0001] This disclosure generally relates to an apparatus for diluting the hydrogen concentration in a fuel cell exhaust system. Background Technology

[0002] Fuel cells can be used to provide electrical energy. A fuel cell may include an anode and a cathode. An electrolyte may be provided between the anode and cathode to facilitate ion transfer between them. The anode may provide a flow of hydrogen. The cathode may provide a flow of oxygen, for example, through an air flow. The anode and cathode may react with hydrogen and oxygen respectively, exchange ions through the electrolyte, and generate an electric current, which can be used to power a system such as an electric vehicle. Summary of the Invention

[0003] An apparatus for diluting the hydrogen concentration in a fuel cell exhaust system is provided. The apparatus includes a fuel cell exhaust line configured to receive an airflow from a connected fuel cell and including a hydrogen airflow. The apparatus also includes a mixing chamber configured to receive the hydrogen airflow and to mix an airflow with the hydrogen airflow. The mixing chamber includes a mixing mesh comprising at least one tab feature configured to alter the flow direction of at least a portion of the hydrogen airflow and the airflow and to generate a turbulent region within the mixing chamber.

[0004] In some embodiments, the hybrid mesh further includes a wireframe formed as a closed polygon shape. The at least one tab feature is connected to the wireframe.

[0005] In some embodiments, the wireframe is oriented vertically relative to the longitudinal axis of the mixing chamber. The mixing mesh includes a plurality of tab features. At least one of the plurality of tab features is angled away from the vertical orientation of the wireframe.

[0006] In some embodiments, the mixing chamber includes cylindrical walls.

[0007] In some embodiments, the mixing chamber includes a conical portion.

[0008] In some embodiments, the mixing chamber includes an expansion portion.

[0009] In some embodiments, the mixing chamber includes: a first end configured to receive a hydrogen flow from a fuel cell exhaust line; and a conical portion connected to the first end and including a mixing mesh. The mixing chamber also includes: a cylindrical central portion connected to the conical portion; and an expansion portion connected to the cylindrical central portion.

[0010] According to an alternative embodiment, a fuel cell system is provided, including a mixing chamber configured to dilute the hydrogen concentration in a fuel cell exhaust stream. The fuel cell system includes: a fuel cell including an anode and a cathode; a fuel cell exhaust line configured to receive an airflow from the fuel cell and including a hydrogen airflow; and a mixing chamber configured to receive the hydrogen airflow. The mixing chamber is configured to mix an airflow with the hydrogen airflow. The mixing chamber includes a mixing mesh including at least one tab feature configured to alter the flow direction of at least a portion of the hydrogen airflow and the airflow and to generate a turbulent region within the mixing chamber.

[0011] In some embodiments, the hybrid mesh further includes a wireframe formed as a closed polygon shape. The at least one tab feature is connected to the wireframe.

[0012] In some embodiments, the wireframe is oriented vertically relative to the longitudinal axis of the mixing chamber, and the mixing mesh includes a plurality of tab features. At least one of the plurality of tab features is angled away from the vertical orientation of the wireframe.

[0013] In some embodiments, the mixing chamber includes cylindrical walls.

[0014] In some embodiments, the mixing chamber includes a conical portion.

[0015] In some embodiments, the mixing chamber includes an expansion portion.

[0016] In some embodiments, the mixing chamber includes a first end configured to receive a hydrogen flow from a fuel cell exhaust line. The mixing chamber also includes: a conical portion connected to the first end and including a mixing mesh; a cylindrical central portion connected to the conical portion; and an expansion portion connected to the cylindrical central portion.

[0017] According to an alternative embodiment, a vehicle is provided that includes a fuel cell system comprising a mixing chamber configured to dilute the hydrogen concentration in a fuel cell exhaust stream. The vehicle includes: a fuel cell including an anode and a cathode; a fuel cell exhaust line configured to receive an airflow from the fuel cell and including a hydrogen airflow; and a mixing chamber configured to receive the hydrogen airflow. The mixing chamber is configured to mix an airflow with the hydrogen airflow. The mixing chamber includes a mixing mesh including at least one tab feature configured to alter the flow direction of at least a portion of the hydrogen airflow and the airflow and to generate a turbulent region within the mixing chamber.

[0018] In some embodiments, the hybrid mesh further includes a wireframe formed as a closed polygon shape. The at least one tab feature is connected to the wireframe.

[0019] In some embodiments, the wireframe is oriented vertically relative to the longitudinal axis of the mixing chamber, and the mixing mesh includes a plurality of tab features. At least one of the plurality of tab features is angled away from the vertical orientation of the wireframe.

[0020] In some embodiments, the mixing chamber includes a conical portion.

[0021] In some embodiments, the mixing chamber includes an expansion portion.

[0022] In some embodiments, the mixing chamber includes: a first end configured to receive a hydrogen flow from a fuel cell exhaust line; a conical portion connected to the first end and including a mixing mesh; a cylindrical central portion connected to the conical portion; and an expansion portion connected to the cylindrical central portion.

[0023] 1. An apparatus for diluting the hydrogen concentration in a fuel cell exhaust system, the apparatus comprising:

[0024] A fuel cell exhaust line configured to receive gas flow from a connected fuel cell and including a hydrogen gas flow; and

[0025] A mixing chamber configured to receive the hydrogen gas flow and to mix an air flow with the hydrogen gas flow, wherein the mixing chamber includes a mixing mesh having at least one tab feature configured to change the flow direction of the hydrogen gas flow and to generate a turbulent region within the mixing chamber.

[0026] 2. The device according to claim 1, wherein the hybrid mesh further includes a wireframe formed into a closed polygonal shape; and

[0027] The at least one tab feature is connected to the wireframe.

[0028] 3. The device according to claim 2, wherein the wire frame is oriented perpendicularly to the longitudinal axis of the mixing chamber;

[0029] The hybrid mesh includes multiple convex features; and

[0030] Wherein, at least one of the plurality of tab features is angled away from the vertical orientation of the wireframe.

[0031] 4. The device according to claim 1, wherein the mixing chamber comprises a cylindrical wall.

[0032] 5. The device according to claim 1, wherein the mixing chamber includes a conical portion.

[0033] 6. The device according to claim 1, wherein the mixing chamber includes an expansion section.

[0034] 7. The device according to claim 1, wherein the mixing chamber comprises:

[0035] The first end is configured to receive the hydrogen flow from the fuel cell exhaust line;

[0036] A tapered portion, which is connected to the first end and includes the hybrid mesh;

[0037] A cylindrical central portion, which connects to the conical portion; and

[0038] The expanded portion is connected to the central cylindrical portion.

[0039] 8. A fuel cell system comprising a mixing chamber configured to dilute the hydrogen concentration in a fuel cell exhaust stream, the fuel cell system comprising:

[0040] A fuel cell, which includes an anode and a cathode;

[0041] A fuel cell exhaust line configured to receive gas flow from the fuel cell and comprising a hydrogen gas flow; and

[0042] A mixing chamber configured to receive the hydrogen gas flow and to mix an air flow with the hydrogen gas flow, wherein the mixing chamber includes a mixing mesh having at least one tab feature configured to change the flow direction of the hydrogen gas flow and to generate a turbulent region within the mixing chamber.

[0043] 9. The fuel cell system according to claim 8, wherein the hybrid network further includes a wireframe formed in a closed polygonal shape; and

[0044] The at least one tab feature is connected to the wireframe.

[0045] 10. The fuel cell system according to claim 9, wherein the wireframe is oriented perpendicularly to the longitudinal axis of the mixing chamber;

[0046] The hybrid mesh includes multiple convex features; and

[0047] Wherein, at least one of the plurality of tab features is angled away from the vertical orientation of the wireframe.

[0048] 11. The fuel cell system according to claim 8, wherein the mixing chamber comprises a cylindrical wall.

[0049] 12. The fuel cell system according to claim 8, wherein the mixing chamber includes a conical portion.

[0050] 13. The fuel cell system according to claim 8, wherein the mixing chamber includes an expansion portion.

[0051] 14. The fuel cell system according to claim 8, wherein the mixing chamber comprises:

[0052] The first end is configured to receive the hydrogen flow from the fuel cell exhaust line;

[0053] A tapered portion, which is connected to the first end and includes the hybrid mesh;

[0054] A cylindrical central portion, which connects to the conical portion; and

[0055] The expanded portion is connected to the central cylindrical portion.

[0056] 15. A vehicle comprising a fuel cell system, the fuel cell system including a mixing chamber configured to dilute the hydrogen concentration in a fuel cell exhaust stream, the vehicle comprising:

[0057] A fuel cell, which includes an anode and a cathode;

[0058] A fuel cell exhaust line configured to receive gas flow from the fuel cell and comprising a hydrogen gas flow; and

[0059] A mixing chamber configured to receive the hydrogen gas flow and to mix an air flow with the hydrogen gas flow, wherein the mixing chamber includes a mixing mesh having at least one tab feature configured to change the flow direction of the hydrogen gas flow and to generate a turbulent region within the mixing chamber.

[0060] 16. The vehicle according to claim 15, wherein the hybrid mesh further includes a wireframe formed in a closed polygonal shape; and

[0061] The at least one tab feature is connected to the wireframe.

[0062] 17. The vehicle according to claim 16, wherein the wireframe is oriented perpendicularly to the longitudinal axis of the mixing chamber;

[0063] The hybrid mesh includes multiple convex features; and

[0064] Wherein, at least one of the plurality of tab features is angled away from the vertical orientation of the wireframe.

[0065] 18. The vehicle according to claim 15, wherein the mixing chamber includes a conical portion.

[0066] 19. The vehicle according to claim 15, wherein the mixing chamber includes an expansion portion.

[0067] 20. The vehicle according to claim 15, wherein the mixing chamber comprises:

[0068] The first end is configured to receive the hydrogen flow from the fuel cell exhaust line;

[0069] A tapered portion, which is connected to the first end and includes the hybrid mesh;

[0070] A cylindrical central portion, which connects to the conical portion; and

[0071] The expanded portion is connected to the central cylindrical portion.

[0072] The above features and advantages, as well as other features and advantages, of this disclosure will readily become apparent from the following detailed description of the best mode for carrying out this disclosure when understood in conjunction with the accompanying drawings. Attached Figure Description

[0073] Figure 1 An exhaust gas mixing device according to the present disclosure is schematically illustrated for mixing a hydrogen gas stream in an exhaust gas stream with an air stream in order to dilute the hydrogen gas.

[0074] Figure 2 An exemplary hybrid mesh according to this disclosure is schematically illustrated in a front perspective view;

[0075] Figure 3 The following perspective views schematically illustrate the provisions of this disclosure. Figure 2 Hybrid network;

[0076] Figure 4 The illustrations show exemplary test results according to this disclosure, illustrating the results without a hybrid network setup. Figure 1 In the case of mixing chambers, the gases in the mixing chamber are mixed;

[0077] Figure 5 The illustrations depict exemplary test results according to this disclosure, illustrating the effects of hybrid networks. Figure 1 The mixing of gases within the mixing chamber;

[0078] Figure 6 These are graphs illustrating exemplary test results according to this disclosure, illustrating the results without a hybrid mesh setup. Figure 1 The mole fraction of hydrogen in the mixing chamber under the condition of mixing chamber;

[0079] Figure 7 These are graphs illustrating exemplary test results according to this disclosure, illustrating the effects of having a hybrid mesh setup. Figure 1 The mole fraction of hydrogen in the mixing chamber under the condition of mixing chamber; and

[0080] Figure 8 An exemplary vehicle according to the present disclosure is schematically illustrated, the vehicle including a fuel cell system including a fuel cell exhaust line equipped with a mixing chamber. Detailed Implementation

[0081] Under certain conditions, fuel cells may not allow the hydrogen supplied to the anode to react sufficiently. As a result, components of the exhaust stream emitted from the fuel cell may include hydrogen. Hydrogen is reactive, and excessively high concentrations in the surrounding environment may be undesirable.

[0082] An apparatus is provided for diluting the hydrogen concentration in a fuel cell exhaust system. Ambient air can be drawn into the exhaust stream, for example, through the Venturi effect. This ambient air can be drawn into the exhaust stream to effectively dilute the hydrogen in the exhaust stream and thus avoid the reactivity of the hydrogen. However, the hydrogen flow and air flow in the exhaust line may remain effectively separated and poorly mixed within the exhaust line, making it impossible to dilute the hydrogen to a non-reactive state. The provided apparatus includes a mixing mesh for generating turbulence in the exhaust stream and promoting the mixing of the constituent gases within the exhaust stream.

[0083] In some embodiments, typical operation of a fuel cell system with an unmodified exhaust line may not result in hydrogen concentrations exceeding a threshold. However, harsh transient conditions or a constantly open fuel injector may cause the system to operate outside its typical range. The included improvements (including a mixing mesh disposed within the exhaust stream) mix the exhaust and prevent spikes or unexpected periods of high hydrogen concentration from affecting the hydrogen concentration in the exhaust stream output, resulting in a lower molar fraction of hydrogen in the exhaust stream output.

[0084] Referring now to the accompanying drawings, in which similar reference numerals are used throughout several views to indicate similar features. Figure 1An exhaust mixing device 100 is schematically illustrated for mixing a hydrogen stream 130 within an exhaust flow with an air stream 140 configured to dilute the hydrogen. The exhaust mixing device 100 includes a fuel cell exhaust line 110 and a mixing chamber 120. The mixing chamber 120 is illustrated as including: a first end 128 defining an upstream end of the mixing chamber 120; and a second end 129 defining a downstream end of the mixing chamber 120. The mixing chamber 120 may be described as a hollow tube, and each of the first end 128 and the second end 129 may be described as an open end of the hollow tube. The mixing chamber 120 is attached to the fuel cell exhaust line 110 using an optional attachment bracket 115. The fuel cell exhaust line 110 is configured to receive a gas stream from a connected fuel cell, the gas stream comprising reactants and waste products from the fuel cell reaction. The fuel cell exhaust line 110 may include a hydrogen stream 130, which may be the entirety of the exhaust flow within the fuel cell exhaust line 110 or a component of the exhaust flow within the fuel cell exhaust line 110. The fuel cell exhaust line 110 may include a cylindrical portion 112 and a conical nozzle portion 114. The conical nozzle portion 114 reduces the cross-section of the hydrogen flow 130 and increases the velocity of the hydrogen flow 130 compared to the hydrogen flow 130 within the cylindrical portion 112. The hydrogen flow 130 exits the conical nozzle portion 114 and enters a first end 128 of the mixing chamber 120. The conical nozzle portion 114 does not completely cover the first end 128, resulting in a gap between the conical nozzle portion 114 and the first end 128. Due to this gap, an airflow 140 can be drawn from the surrounding air into the first end 128 of the mixing chamber 120 through the Venturi effect of the hydrogen flow 130 entering the first end 128.

[0085] Hydrogen stream 130 and air stream 140 flow simultaneously through mixing chamber 120. If mixing chamber 120 is a straight-walled cylinder and has an open, unobstructed cross-section, hydrogen stream 130 and air stream 140 can be slightly mixed, wherein the component of exit stream 160 exiting the second end 129 of mixing chamber 120 includes a substantially unmixed portion of hydrogen stream 130. This unmixed portion of hydrogen stream 130 may include hydrogen in a reactive state or concentration.

[0086] A mixing mesh 170 is disposed within a mixing chamber 120. The mixing mesh 170 is oriented perpendicularly to the longitudinal axis of the mixing chamber 120. The mixing mesh 170 may include one or more tab features configured to alter the flow direction of at least a portion of one of the hydrogen flow 130 and the air flow 140, thereby creating a turbulent region 150 downstream of the mixing mesh 170 within the mixing chamber 120. Due to the presence of the turbulent region 150, the exiting flow 160 may include a well-mixed flow, comprising hydrogen diluted with air.

[0087] The mixing chamber 120 is illustrated as including a conical portion 122, a relatively narrow central portion 124, and an expansion portion 126. As gas flows through the conical portion 122 and the central portion 124 and enters the expansion portion 126, additional turbulence is generated, thereby enhancing the mixing of the gas within the mixing chamber 120.

[0088] The mixing chamber 120 may include alternative configurations. For example, the walls of the mixing chamber 120 may be straight or cylindrical. In another example, the walls of the mixing chamber 120 may include a conical nozzle portion or an expansion portion, but not both. In yet another example, the opening of the mixing chamber 120 may be formed concurrently with or integrally with the outlet of the fuel cell exhaust line 110, wherein air is introduced by one or more pipes that protrude perpendicularly to the hydrogen flow 130 through the walls of the mixing chamber 120.

[0089] Figure 2 An exemplary hybrid mesh 170 is schematically illustrated in a front perspective view. The hybrid mesh 170 includes a wireframe 172. The exemplary wireframe 172 includes a closed polygonal shape and includes components configured for use with… Figure 1 The inner surface of the mixing chamber 120 contacts the outer feature 175. In one embodiment, feature 175 may be welded or otherwise joined to... Figure 1 The inner surface of the mixing chamber 120. The mixing mesh 170 also includes a plurality of tabs 174 connected to the wire frame 172. The tabs 174 may be formed in a plane with the wire frame 172. Figure 2 In one embodiment, the tab 174 is bent or formed at an angle relative to the plane defined by the wire frame 172. As the gas moves upstream of the mixing mesh 170, the gas can travel along... Figure 1 The mixing chamber 120 moves longitudinally. When the gas moves past the convex plate 174, the convex plate 174 acts on the gas and causes the gas to move along the longitudinal direction. Figure 1 The gas moves in different directions along the longitudinal direction of the mixing chamber 120. This movement of the gas in the non-longitudinal direction causes turbulence or mixing of the gas moving through the mixing mesh 170.

[0090] Figure 3 The perspective view is shown schematically below. Figure 2 The hybrid mesh 170 includes a wireframe 172 and a tab 174.

[0091] Figure 4 Exemplary test results are illustrated, showing the results without a mixing mesh setting. Figure 1 The gases in the mixing chamber 120 are mixed. Hydrogen flow 130 is illustrated within the fuel cell exhaust line 110. Hydrogen flow 130' is illustrated, representing hydrogen flow 130 entering... Figure 1 The hydrogen flow shortly after mixing chamber 120. The illustration shows hydrogen flow 130'', which represents hydrogen flow 130 as it passes through... Figure 1 The hydrogen flow after conversion in mixing chamber 120. Similarly, airflow 140' is illustrated, representing the flow drawn in through the venturi effect. Figure 1 The air at the first end 128 is affected by the Venturi effect generated by the hydrogen flow 130 entering the mixing chamber 120. The illustrated test results show that the hydrogen flow 130' remains largely unmixed throughout the mixing chamber. As the air flow 140' passes through the expansion portion of the mixing chamber 120, they become a moderately mixed flow 140''.

[0092] Figure 5 Exemplary test results are illustrated, showing the results in a configuration including a hybrid network 170. Figure 1 The gas is mixed within the mixing chamber 120. Hydrogen flow 130 is illustrated within the fuel cell exhaust line 110. Hydrogen flow 130' is illustrated, representing hydrogen flow 130 entering... Figure 1 The hydrogen flow shortly after mixing chamber 120. Similarly, airflow 140' is illustrated, representing the flow drawn in through the venturi effect. Figure 1 The air at the first end 128, the Venturi effect is generated by the hydrogen flow 130 entering the mixing chamber 120. Figure 1 The mixing network 170 is illustrated within the mixing chamber 120. A turbulent region 150 is also illustrated, in which the hydrogen flow 130' and the air flow 140' (which are visually distinct upstream or to the left of the mixing network 170) rapidly dissipate into an indistinguishable mixed flow downstream or to the right of the mixing network 170. Thus, the exit flow 160 is well mixed, and the previously concentrated hydrogen is fully or substantially mixed and therefore diluted by the air.

[0093] Figure 6 This is a graph 200 illustrating exemplary test results, which show that when the hybrid network 170 is not set... Figure 1 The diagram shows the mole fraction of hydrogen gas in the mixing chamber 120 under the condition of mixing chamber 120. The horizontal axis 202 is illustrated, which describes... Figure 1 The length of the mixing chamber 120 is shown, wherein the left side of the horizontal axis corresponds to the inlet of the mixing chamber 120, and wherein the right side of the horizontal axis corresponds to the outlet of the mixing chamber 120, at which exhaust gas is discharged into the surrounding air. The vertical axis 204 is illustrated, which describes the length of the mixing chamber 120. Figure 1 The mole fraction of hydrogen gas measured in mixing chamber 120. Curve 210 illustrates the effect of... Figure 1 The results of hydrogen sampling at various points within mixing chamber 120, where no mixing mesh exists. The initial spike in curve 210 on the left side of graph 200 corresponds to... Figure 1The amount of hydrogen present at the inlet of mixing chamber 120. The stable value on the right side of graph 200 in curve 210 corresponds to the amount of hydrogen present at the inlet of mixing chamber 120. Figure 1 The amount of hydrogen present at the outlet of mixing chamber 120. The transient measurement between the peak to the left of curve 210 and the stable value to the right of curve 210 represents the amount of hydrogen present at the inlet and outlet. Figure 1 The mixing and uncertain readings of turbulent flow within mixing chamber 120. One can see that the mole fraction values ​​on the left side of curve 210 in graph 200 show that the hydrogen mole fraction stabilizes at slightly below 0.07, or 7% hydrogen presence upon exiting. Figure 1 In the exhaust flow of the mixing chamber 120.

[0094] Figure 7 This is a graph 300 illustrating exemplary test results, which illustrate the results of testing in a system with settings... Figure 1 The diagram illustrates the mole fraction of hydrogen in the mixing chamber 120 within the mixing mesh 170. The horizontal axis 302 is shown, which depicts... Figure 1 The length of the mixing chamber 120 is shown, with the left side of the horizontal axis corresponding to the inlet of the mixing chamber 120, and the right side of the horizontal axis corresponding to the outlet of the mixing chamber 120, where the exhaust stream is discharged into the surrounding air. The vertical axis 304 is illustrated, which describes the mole fraction of hydrogen measured in the mixing chamber. Curve 310 illustrates the... Figure 1 The results of hydrogen sampling at various points within mixing chamber 120, where mixing mesh 170 exists, are shown. The initial spike in curve 310 on the left side of graph 300 corresponds to the... Figure 1 The amount of hydrogen present at the inlet of mixing chamber 120. It can be seen that the initial mole fraction value on graph 300 (corresponding to the peak in curve 310) is similar to the initial mole fraction value on graph 200 (corresponding to the peak in curve 210). Entering Figure 1 The exhaust flow from mixing chamber 120 includes a similar hydrogen mole fraction in both the tests illustrated in Figure 200 and Figure 300. The stable value on the right side of curve 310 in Figure 300 corresponds to... Figure 1 The amount of hydrogen present at the outlet of mixing chamber 120. The stable value to the right of curve 310 is approximately 0.06 or 6% hydrogen present at the outlet. Figure 1 In the exhaust flow of the mixing chamber 120. (Comparison) Figure 6 curve 210 and Figure 7 From the stable value of curve 310, it can be seen that this is achieved due to the presence of the hybrid network 170. Figure 1 The improved mixing within the mixing chamber 120 allows more air to mix with the exhaust stream, thereby resulting in a lower hydrogen content in the exhaust stream leaving the mixing chamber 120.

[0095] Figure 8 An exemplary vehicle 400 is schematically illustrated, including a fuel cell system 420, an exhaust line 110, and a mixing chamber 120. A hydrogen storage tank 410 supplies a hydrogen stream to the fuel cell system 420, which uses the hydrogen stream to generate electricity for use by the vehicle 400. The fuel cell system 420 generates an exhaust stream that includes a portion of this stream, including hydrogen. The mixing chamber 120 operates as disclosed herein to reduce the hydrogen concentration in the exhaust stream as it leaves the vehicle 400.

[0096] Although the best mode for carrying out this disclosure has been described in detail, those skilled in the art to which this disclosure pertains will recognize various alternative designs and embodiments for practicing this disclosure within the scope of the appended claims.

Claims

1. An apparatus for diluting the hydrogen concentration in a fuel cell exhaust system, the apparatus comprising: A fuel cell exhaust line, configured to receive gas flow from a connected fuel cell and including a hydrogen gas flow; as well as A mixing chamber configured to receive the hydrogen gas flow and to mix an air flow with the hydrogen gas flow, wherein the mixing chamber includes a mixing mesh, the mixing mesh including at least one tab feature configured to change the flow direction of the hydrogen gas flow and to generate a turbulent region within the mixing chamber; The hybrid mesh further includes a wireframe formed into a closed polygonal shape; and The at least one tab feature is connected to the wireframe.

2. The device according to claim 1, wherein, The wireframe is oriented perpendicularly to the longitudinal axis of the mixing chamber; The hybrid mesh includes multiple convex features; and Wherein, at least one of the plurality of tab features is angled away from the vertical orientation of the wireframe.

3. The device according to claim 1, wherein, The mixing chamber includes cylindrical walls.

4. The device according to claim 1, wherein, The mixing chamber includes a conical section.

5. The device according to claim 1, wherein, The mixing chamber includes an expansion section.

6. The device according to claim 1, wherein, The mixing chamber includes: The first end is configured to receive the hydrogen flow from the fuel cell exhaust line; A tapered portion, which is connected to the first end and includes the hybrid mesh; A cylindrical central portion, which connects to the conical portion; and The expanded portion is connected to the central cylindrical portion.

7. A fuel cell system comprising a mixing chamber configured to dilute the hydrogen concentration in a fuel cell exhaust stream, the fuel cell system comprising: A fuel cell, which includes an anode and a cathode; A fuel cell exhaust line, configured to receive gas flow from the fuel cell and including a hydrogen gas flow; as well as A mixing chamber configured to receive the hydrogen gas flow and to mix an air flow with the hydrogen gas flow, wherein the mixing chamber includes a mixing mesh, the mixing mesh including at least one tab feature configured to change the flow direction of the hydrogen gas flow and to generate a turbulent region within the mixing chamber; The hybrid mesh further includes a wireframe formed into a closed polygonal shape; and The at least one tab feature is connected to the wireframe.

8. The fuel cell system according to claim 7, wherein, The wireframe is oriented perpendicularly to the longitudinal axis of the mixing chamber; The hybrid mesh includes multiple convex features; and Wherein, at least one of the plurality of tab features is angled away from the vertical orientation of the wireframe.

9. The fuel cell system according to claim 7, wherein, The mixing chamber includes cylindrical walls.

10. The fuel cell system according to claim 7, wherein, The mixing chamber includes a conical section.

11. The fuel cell system according to claim 7, wherein, The mixing chamber includes an expansion section.

12. The fuel cell system according to claim 7, wherein, The mixing chamber includes: The first end is configured to receive the hydrogen flow from the fuel cell exhaust line; A tapered portion, which is connected to the first end and includes the hybrid mesh; A cylindrical central portion, which connects to the conical portion; and The expanded portion is connected to the central cylindrical portion.

13. A vehicle comprising a fuel cell system, the fuel cell system including a mixing chamber configured to dilute the hydrogen concentration in a fuel cell exhaust stream, the vehicle comprising: A fuel cell, which includes an anode and a cathode; A fuel cell exhaust line, configured to receive gas flow from the fuel cell and including a hydrogen gas flow; as well as A mixing chamber configured to receive the hydrogen gas flow and to mix an air flow with the hydrogen gas flow, wherein the mixing chamber includes a mixing mesh, the mixing mesh including at least one tab feature configured to change the flow direction of the hydrogen gas flow and to generate a turbulent region within the mixing chamber; The hybrid mesh further includes a wireframe formed into a closed polygonal shape; and The at least one tab feature is connected to the wireframe.

14. The vehicle according to claim 13, wherein, The wireframe is oriented perpendicularly to the longitudinal axis of the mixing chamber; The hybrid mesh includes multiple convex features; and Wherein, at least one of the plurality of tab features is angled away from the vertical orientation of the wireframe.

15. The vehicle according to claim 13, wherein, The mixing chamber includes a conical section.

16. The vehicle according to claim 13, wherein, The mixing chamber includes an expansion section.

17. The vehicle according to claim 13, wherein, The mixing chamber includes: The first end is configured to receive the hydrogen flow from the fuel cell exhaust line; A tapered portion, which is connected to the first end and includes the hybrid mesh; A cylindrical central portion, which connects to the conical portion; and The expanded portion is connected to the central cylindrical portion.

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