Concave fuel cell separator drain

Abstract

A concave fuel cell separation drain is disclosed. A vehicle includes a high voltage bus and an electric motor electrically connected to the high voltage bus. The vehicle also includes a fuel cell system electrically connected to the high voltage bus. The fuel cell system includes a fuel stack and a reservoir fluidly connected to the fuel stack. The reservoir has a concave, generally conical bottom wall that extends upward into a cavity of the reservoir and forms an apex in the cavity of the reservoir. The reservoir also includes a valve receiving portion extending from a side wall of the reservoir into the cavity of the reservoir. The valve receiving portion defines a drain hole and an outlet hole having a bottom edge disposed proximate to the apex of the bottom wall. The fuel cell system also includes a drain pipe in fluid communication with the drain hole and a control valve disposed in the valve receiving portion and adapted to control fluid communication between the outlet hole and the drain hole.

Description

Technical Field

[0001] The present disclosure generally relates to water removal systems for fuel cells. Background Art

[0002] During the operation of the fuel cell, byproducts (such as product water and nitrogen) and unconsumed hydrogen may be formed on the anode side of the fuel cell stack. In some known systems, attempts are made to control the accumulation of product water and the accumulation of nitrogen to avoid fuel cell performance degradation and / or fuel cell system shutdown. A known solution is to release water and nitrogen via a channel downstream of the fuel cell stack. Using this solution, the channel is connected to a valve to controllably release water and nitrogen from the fuel cell stack. During the operation of the fuel cell in cold weather, when water may freeze in the channel or other areas of the valve or fuel cell with a smaller cross-sectional area, this solution leads to the potential for problems. The resulting ice may cause at least a portion of the channel to block and prevent fluid flow (e.g., removal of water and nitrogen), which may inhibit the function of the fuel cell system.

[0003] To avoid clogging of the fuel cell separator drain ports in cold ambient conditions, various solutions utilizing additional hardware have been employed. For example, a "purge reservoir" may be employed to provide an open path adjacent to the ice. However, in many cases, the increase in water volume due to freezing may cause the reservoir outlet to become completely blocked, thereby inhibiting the discharge of the fluid.

[0004] When the vehicle is parked on a slope, ice blockage may also inhibit the discharge of the fluid. In many cases, the reservoir outlet is arranged at the periphery of the reservoir. When the vehicle is parked on a slope, ice blockage may occur at the reservoir outlet, thereby inhibiting the discharge of the fluid. Summary of the invention

[0005] A vehicle includes a high voltage bus and an electric motor electrically connected to the high voltage bus. The vehicle also includes a fuel cell system electrically connected to the high voltage bus. In some embodiments, the fuel cell system includes an anode side, a cathode side, and a membrane disposed between the anode side and the cathode side.

[0006] The fuel cell system includes a fuel stack and a reservoir fluidly connected to the fuel stack. In some aspects, the reservoir includes an inlet adapted to receive a fluid mixture of hydrogen, nitrogen, and water from an output of an anode side of the fuel stack.

[0007] The reservoir has a concave, generally conical bottom wall that extends upwardly into the cavity of the reservoir and forms an apex within the cavity of the reservoir. In some approaches, at least a portion of the concave bottom wall extends upwardly into the cavity of the reservoir at an angle of between about 15 and 25 degrees relative to a horizontal plane extending between the bottom edges of the side walls of the reservoir.

[0008] The reservoir further comprises a valve receiver extending from a side wall of the reservoir into the cavity of the reservoir.In some aspects, at least a portion of the valve receiver protrudes through the concave generally conical bottom wall.

[0009] The valve receiving portion defines a discharge hole and an outlet hole having a bottom edge disposed near the vertex of the bottom wall. The fuel cell system also includes a discharge pipe in fluid communication with the discharge hole and a control valve disposed in the valve receiving portion and adapted to control fluid communication between the outlet hole and the discharge hole.

[0010] In some embodiments, at a first vehicle inclination in a first inclination direction, the water level is maintained at a predetermined height near the apex of the bottom wall. At a second vehicle inclination in a second inclination direction opposite to the first inclination direction, the water level may be maintained at a predetermined height near the apex of the bottom wall.

[0011] A fuel cell system may include a fuel stack and a reservoir fluidly connected to the fuel stack. The reservoir may have a concave, generally conical bottom wall forming an apex within a cavity of the reservoir. The concave, generally conical bottom wall may extend upward into the cavity of the reservoir at an angle between about 15 and 25 degrees relative to a horizontal plane extending between bottom edges of the side walls of the reservoir.

[0012] The reservoir may further include a valve receiving portion extending into the cavity of the reservoir. The valve receiving portion may be a tubular valve receiving portion extending into the cavity of the reservoir. The valve receiving portion may define a discharge aperture and an outlet aperture having a bottom edge disposed at the vertex of the bottom wall. The outlet aperture may extend substantially in a plane substantially orthogonal to a plane defined by the discharge aperture.

[0013] In one aspect, the outlet aperture is generally circular. In another aspect, the outlet aperture is generally triangular and may be oriented such that a first corner and a second corner of the generally triangular outlet aperture are disposed above a third corner of the generally triangular outlet aperture.

[0014] In some aspects, the valve receiver includes an abutment surface disposed within the cavity of the reservoir between longitudinal walls of the tubular valve receiver. The abutment surface may define the outlet aperture.

[0015] A control valve may be disposed within the valve receiving portion and may be adapted to control fluid communication between the outlet aperture and the discharge aperture.

[0016] A water removal system for a fuel cell may include a reservoir connected to a fuel cell fluid. The reservoir may have a concave, generally conical bottom wall forming an apex in a cavity of the reservoir. The concave, generally conical bottom wall extends upward into the cavity of the reservoir at an angle of between about 15 and 25 degrees relative to a horizontal plane extending between bottom edges of the side walls of the reservoir.

[0017] The reservoir may further comprise a valve receiver extending into the cavity of the reservoir.The valve receiver may define a discharge aperture and an outlet aperture having a bottom edge disposed at an apex of the bottom wall.

[0018] The water removal system may further include a control valve disposed within the valve receiving portion and adapted to control fluid communication between the outlet aperture and the discharge aperture.

[0019] At a first vehicle inclination in a first inclination direction, the water level can be maintained at a predetermined height near the apex of the bottom wall.At a second vehicle inclination in a second inclination direction opposite to the first inclination direction, the water level can be maintained at a predetermined height near the apex of the bottom wall. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A block diagram of a vehicle powered by a fuel cell system is shown.

[0021] Figure 2 A schematic diagram of a fuel cell system is shown.

[0022] Figure 3 A perspective view showing a schematic diagram of a separator for a fuel cell system is shown.

[0023] Figure 4 A cross-sectional side view of a schematic diagram of a separator for a fuel cell system is shown.

[0024] Figure 5 A cross-sectional elevation view showing a schematic diagram of a separator for a fuel cell system.

[0025] Figure 6 A cross-sectional top view showing a schematic diagram of a separator for a fuel cell system is shown.

[0026] Figure 7 A cross-sectional side view showing a schematic diagram of an alternative separator for a fuel cell system.

[0027] Figure 8 A cross-sectional side view of a schematic diagram of a separator for a fuel cell system in a horizontal orientation is shown.

[0028] Fig. 9 A cross-sectional side view of a schematic diagram of a separator for a fuel cell system in a first tilted orientation is shown.

[0029] Fig.10 A cross-sectional side view of a schematic diagram of a separator for a fuel cell system in a second tilted orientation is shown. DETAILED DESCRIPTION

[0030] This describes embodiments of the present disclosure. However, it should be understood that the disclosed embodiments are merely examples, and other embodiments may take various and alternative forms. The drawings need not be drawn to scale; some features may be exaggerated or minimized to show the details of specific components. Therefore, the specific structural and functional details disclosed herein should not be interpreted as limiting, but only as a representative basis for teaching those skilled in the art to utilize the present invention in various forms. As will be understood by those of ordinary skill in the art, the various features shown and described with reference to any of the figures may be combined with the features shown in one or more other figures to produce embodiments that are not explicitly shown or described. The combination of features shown provides representative embodiments for typical applications. However, various combinations and variations of features consistent with the teachings of the present disclosure may be desired for specific applications or implementations.

[0031] Now refer to Figure 1 , the vehicle 10 may be powered by a fuel cell system 12. The fuel cell system 12 may be electrically connected to a high voltage bus 14. A traction battery 16 may be electrically connected to the high voltage bus 14. An electrical load 18 may be electrically connected to the high voltage bus 14. An electric machine 20 may be electrically connected to the high voltage bus 14 via a power inverter. The electric machine 20 may be mechanically connected to a transmission 22. The transmission 22 may be mechanically connected to drive wheels 24 of the vehicle 10.

[0032] The fuel cell system 12 can provide power to operate the electric machine 20 to propel the vehicle 10 or perform other vehicle functions. The fuel cell system 12 can generate electricity that can be consumed by components (such as electrical loads 18) connected to the high voltage bus 14. The electricity generated by the fuel cell system 12 can also be stored by the traction battery 16. The electric machine 20 converts electrical energy into rotational mechanical energy to drive the transmission 22. The transmission 22 may include gears and clutches configured to convert the rotational energy of the electric machine 20 into rotational energy at the drive wheels 24.

[0033] Figure 2One possible configuration of the fuel cell system 12 is shown as a process flow diagram. As is known in the art, the fuel cell system 12 may be a proton exchange membrane fuel cell (PEMFC). The fuel cell system 12 may include a fuel cell stack 40. The fuel cell stack 40 may include an anode side 42, a cathode side 44, and a membrane 46 therebetween. The fuel cell system 12 may be in electrical communication with, for example, a high voltage bus 14 or a traction battery 16 and provide energy to the high voltage bus 14 or the traction battery 16. The fuel cell stack 40 may also have a cooling circuit (not shown).

[0034] During operation of the fuel cell system 12, water, residual fuel such as hydrogen, and byproducts such as nitrogen may accumulate on the anode side 42 of the fuel cell stack 40. The fuel cell system 12 can be configured to remove liquid water and byproducts and reuse the remaining hydrogen and water vapor. One approach can be to collect these components in a reservoir or separator 50 downstream of the fuel cell stack 40, which is configured to separate at least a portion of the liquid water and / or nitrogen and return the remaining components to the fuel cell stack 40 via a return channel in a recirculation loop.

[0035] A primary fuel source 52 (e.g., a primary hydrogen source) may be connected to the anode side 42 of the fuel cell stack 40. Non-limiting examples of the primary hydrogen source 52 may include a high pressure hydrogen storage tank or a hydride storage device. The primary hydrogen source 52 may be connected to one or more injectors 54. The injector 54 may have a nozzle 56 that supplies hydrogen to a converging portion of a converging-diverging nozzle 58. The diverging portion of the nozzle 58 may be connected to an input 60 of the anode side 42.

[0036] The output 62 of the anode side 42 may be connected to a passive recirculation loop 64. Typically, an excess of hydrogen is provided to the anode side 42 to ensure that there is enough hydrogen available for all of the fuel cells in the fuel cell stack 40. In other words, hydrogen is provided to the fuel cell stack 40 at a stoichiometric ratio above 1 (i.e., at a fuel ratio that is rich relative to the exact electrochemical demand). The recirculation loop 64 is provided so that excess hydrogen not used by the anode side 42 is returned to the input 60 so that it can be used rather than wasted.

[0037] Additionally, the output of the anode side 42 is accumulated liquid and vapor phase water. The anode side 42 requires humidification for efficient chemical conversion and to extend the life of the membrane. A recirculation loop 64 can be used to provide water to humidify the hydrogen before the input 60 of the anode side 42.

[0038] The recirculation loop 64 may include a separator 50 or a water knock-out device. The separator 50 receives a hydrogen stream, a nitrogen stream and a water stream or a fluid mixture of hydrogen, nitrogen and water from the output 62 of the anode side 42. The water may be a mixed phase and contain both liquid and gas phase water. The separator 50 may include a reservoir for maintaining a predetermined capacity of water. The separator 50 removes at least a portion of the liquid phase water by a control valve 68 (also referred to as a discharge valve). The liquid phase water may then leave the separator through a discharge line 66. For example, during the purge process of the fuel cell stack 40, at least a portion of the nitrogen, hydrogen and vapor phase water may also leave and pass through the discharge line 66. The control valve 68 may be tightly integrated with the separator 50. In fact, as will be appreciated, the control valve 68 may be integrated in the separator 50. The remaining fluid in the separator 50 leaves through a passage 70 connected to the ejector 54 in the recirculation loop 64. The fluid in passage 70 is fed into the converging portion of the converging-diverging nozzle 58 where it mixes with the incoming hydrogen from the nozzle 56 and the primary hydrogen source 52 .

[0039] Liquid water may be removed from the anode side 42 by the separator 50 to prevent water blockage within the channels and cells of the anode side 42. Water blockage within the fuel cell stack 40 may result in reduced cell voltage and / or voltage instability within the fuel cell stack 40. Liquid water may also be removed by the separator 50 to prevent blockage or partial blockage within the ejector 54. Liquid water droplets in the diverging portion of the converging-diverging nozzle 58 will effectively create a second venturi section within the nozzle 58 and cause instability in the pumping of the ejector 54.

[0040] The cathode side 44 of the fuel cell stack 40 receives oxygen, for example, as a component in the air source 72. In one embodiment, the compressor 74 is driven by a motor 76 to pressurize the incoming oxygen. The pressurized air is then humidified by a humidifier 78 before entering the cathode side 44. Another separator 80 (shown in dotted lines) may be located downstream of the humidifier 78. The separator 80 may be used to remove liquid water from the humidified air stream before the humidified air stream enters the cathode side 44 of the fuel cell stack 40 at the input 82. Since the liquid water is entrained by the high flow rate air in the humidifier 78, water droplets may be present downstream of the humidifier 78. Liquid water may be removed by the separator 80 to prevent water blockage in the cells of the cathode side 44, which causes a reduction in cell voltage and / or instability in the fuel cell stack 40. The cell stack cathode outlet 84 of the cathode side 44 is connected to a valve 86. The exhaust line 66 from the separator 50 and the exhaust line 88 from the separator 80 may be connected to a line 90 downstream of the valve 86. In other arrangements, the exhaust line may be connected to other locations in the fuel cell system 12 .

[0041] Other system architectures may also be used for the fuel cell system 12. For example, a turbine may be used in addition to the compressor 74 to direct the flow through the cathode side 44. In one example, the turbine is located downstream of the stack cathode outlet 84, and a separator is inserted between the cathode side 44 and the turbine to remove liquid water before the fluid flow enters the turbine.

[0042] Based on the use of the ejector 54 to generate a flow through the anode side 42 and guide the flow through the passive recirculation loop 64, the ejector 54 must overcome any pressure drop in the system, including the pressure drop that is usually significant at both ends of the fuel cell stack 40. The system 12 shown does not include a pump or other device for guiding the flow in the recirculation loop 64, so all compression work is completed by the ejector (or described as a jet pump). In order to achieve this function, the separator 50 can have a low pressure drop at both ends. The separator 50 can be configured to remove larger water droplets from the fluid to prevent water blockage in the recirculation flow of the fuel cell stack 40 or the ejector 54 caused by water droplets. The separator 50 allows vapor phase water and smaller water droplets to remain in the recirculation flow in the channel 70 and return to the ejector 54 for humidification purposes. In one example, the separator 50 removes water droplets with a diameter of 1 mm or more.

[0043] In addition, when the separator 50 receives a fluid flow from the anode side 42, the separator 50 can be designed to be used with hydrogen. Typically, hydrogen may cause material degradation or embrittlement problems, and the materials used in the separator 50 may be compatible with hydrogen. In addition, hydrogen is a small molecule, and many conventional separator devices are not suitable for use with hydrogen because their design (e.g., through conventional threaded connections) may allow leakage. Other conventional separators may include rotating or moving parts (such as rotating blades, etc.), which may be incompatible with hydrogen because the lubricant may poison the fuel cell stack, or hydrogen may degrade or decompose the lubricant.

[0044] The separator 80 also needs to remove larger water droplets from the fluid to prevent water blockage caused by water droplets in the flow in the cathode side 44 of the fuel cell stack 40. The separator 80 allows vapor phase water and smaller water droplets to remain in the flow for humidification. In one approach, the separator 80 removes water droplets that are the same size as or larger than the width of the cathode side 44 flow field channel. In one example, the cathode side flow field channel can be between 0.2 mm and 1.0 mm.

[0045] Figures 3 to 6 Possible configurations of the separator 50 and the drain valve 68 are depicted. The features to be described relate to the separator 50 performing the functions of accumulating liquid water and removing the liquid water from the fuel cell system 12.

[0046] The separator 50 includes a bottom wall 100, a top wall 102, and one or more side walls 104 extending between the bottom wall 100 and the top wall 102. The bottom wall 100, the top wall 102, and the side walls 104 form an interior cavity 106 therebetween.

[0047] In one approach, the top wall 102 is a generally flat top wall. The side wall 104 may form a generally cylindrical or tubular body. The cylindrical body may have an outer diameter between about 75 mm and 100 mm, and may be, for example, about 81 mm. Other suitable configurations and sizes may be contemplated.

[0048] The bottom wall 100 and the side walls 104 may form a reservoir such that liquid water accumulates above the sloping walls of the bottom wall 100 when the separator 50 is oriented vertically.

[0049] In one embodiment, the bottom wall 100 is a generally concave, generally tapered bottom wall. In this way, the bottom wall 100 can extend into the cavity 106. In other embodiments, the bottom wall 100 is a generally concave, non-tapered bottom wall extending into the cavity 106.

[0050] The concave bottom wall 100 can form a vertex 110 at, for example, a central region of the separator 50. The bottom wall 100 extends toward the vertex 110 at an angle relative to a horizontal plane. For example, the bottom wall 100 can form an angle between about 10 degrees and 45 degrees, and more specifically, an angle between about 15 degrees and 25 degrees, relative to a horizontal plane extending between the bottom edges of the side walls 104. In the scheme, the bottom wall 100 forms an angle of about 19.5 degrees. Other suitable angles of inclination are contemplated herein.

[0051] The separator 50 includes a valve receiver 120 formed in the separator 50. The valve receiver 120 defines a receiving aperture 122 disposed through the side wall 104 of the separator 50. The receiving aperture 122 is preferably sized to receive the discharge valve 68.

[0052] The sidewall 124 of the valve receiver 120 extends from the receiving hole 122 into the interior cavity 106 of the separator 50. The sidewall 124 can form a generally cylindrical or tubular body that extends longitudinally into the interior cavity 106 of the separator 50. The cylindrical body can have an outer diameter of approximately 20 mm to 45 mm, and can be, for example, approximately 35 mm. Other suitable configurations and sizes are contemplated.

[0053] A projection 126 of the side wall 124 extends through the tapered bottom wall 100 to an area below the bottom wall 100. At the projection 126, the side wall 124 defines a fluid outlet, also referred to as a drain hole or orifice 130. When the drain valve 68 is energized, the drain hole 130 interfaces with the drain line 66 to allow fluid to flow out of the separator 50 from the interior cavity 106.

[0054] In another approach, temporarily refer to Figure 7 , the valve receiving portion 120 is set through the bottom wall 100. This solution can allow the use of a "rocker" type plunger. In this solution, the discharge valve 68 can be inserted into the valve receiving portion 120 from the bottom of the separator 50.

[0055] The side wall 124 of the valve receiving portion 120 extends from the receiving hole 122 to the abutment surface 132. The abutment surface 132 may be a vertically oriented abutment surface. The portion of the abutment surface 132 adjacent to the protrusion 126 of the side wall 124 extends through the tapered bottom wall 100 to an area below the bottom wall 100.

[0056] The abutment surface 132 defines an outlet hole (also referred to as an outlet orifice 134). The outlet hole 134 may be a vertically oriented outlet hole disposed through the abutment surface 132. The outlet hole 134 may extend substantially in a plane that is generally orthogonal to the plane defined by the discharge hole 130.

[0057] In one approach, the outlet hole 134 is circular. The circular outlet hole may have a diameter between about 3 mm and 6 mm, and may be, for example, about 5 mm.

[0058] In another approach, the outlet hole 134 is triangular. The triangular outlet hole can be oriented in an "upside-down" orientation, with one corner oriented below the other two corners. It has been observed that such a triangular outlet hole can be provided with the same area as a circular hole while providing a larger area in the upper region of the valve receiving portion 120. For example, the height of the triangular outlet hole can be about 17% higher than the height of the circular outlet hole. In yet another approach, the outlet hole 134 is elliptical. Other outlet hole geometries and sizes are contemplated.

[0059] In one approach, the lowest portion of the outlet hole 134 is disposed near the vertex 110 of the bottom wall 100. For example, the lowest portion of the outlet hole 134 may be disposed at the vertex 110 of the bottom wall 100. In other approaches, the lowest portion of the outlet hole 134 is disposed above or below the vertex 110 of the bottom wall 100.

[0060] The valve receiving portion 120 can be formed integrally with the separator 50 so that the valve receiving portion and the separator form an integral unit. For example, the integrally formed separator-receiving portion unit can be formed by an additive manufacturing process such as a three-dimensional printing process. The integrally formed separator-receiving portion unit can be formed of a metal material such as stainless steel or aluminum. Other suitable materials can be considered. In other embodiments, the separator 50 and the valve receiving portion 120 are formed separately and can be assembled to form a separator-receiving portion unit.

[0061] like Figure 3 As shown, the drain valve 68 can be received in the valve receiving portion 120 of the separator 50. The drain valve 68 can be, for example, a solenoid valve including a movable piston or plunger configured to move when the solenoid valve is energized or activated. Other suitable drain valves are contemplated herein.

[0062] The discharge valve 68 may be a normally closed valve. In the closed state, the plunger may seal any passage between the outlet hole 134 of the valve receiver 120 and the discharge hole 130. In the open state, the plunger is positioned so that fluid flow is allowed between the outlet hole 134 and the discharge hole 130. Additional conduits may be used to transport water leaving the separator 50 for recirculation or removal.

[0063] During fuel cell operation, water can be collected in the separator 50. The fuel cell system 12 can control the water level in the separator 50 to a predetermined water level. During fuel cell operation, there may be a preferred water level for operating the fuel cell system 12. In addition, during shutdown, the fuel cell system 12 can be configured to remove water from the separator 50 to prepare for the next operation cycle. The removal of water can also reduce the risk of freezing in cold weather. During fuel cell operation, the discharge valve 68 can be periodically actuated to allow water to flow out of the separator 50 and maintain a preferred water level. For example, when the discharge valve 68 is energized, the plunger can be moved to the open position. When the plunger is in the open position, the outlet hole 134 is fluidly connected to the discharge hole 130. Therefore, the water accumulated in the separator 50 can flow to the discharge hole 130 through the outlet hole 134. In this way, the water level in the separator 50 can be reduced.

[0064] Water collected in the separator 50 can cause problems during freezing weather conditions. After a period of time below freezing temperatures, water within the fuel cell system 12 may freeze and form ice. In the previous scheme, frozen water in the separator can block the outlet holes and prevent water from leaving the separator. Ice in the separator can cause the water level to become too high and ultimately prevent optimal operation of the fuel cell system 12.

[0065] Figure 8 The separator 50 is depicted when the vehicle 10 is in a horizontal plane. In the horizontal orientation, the water level 150 can be maintained at a predetermined height, such as approximately at or below the height of the vertex 110 during freezing conditions. During freezing conditions, the water will freeze, thereby expanding the volume of the water so that the upper ice level 152 is above the height of the vertex 110. It is observed that even during freezing conditions, the upper ice level 152 is still below the top of the outlet hole 134. In this way, water can still be removed from the separator 50 by actuating the plunger of the drain valve 68 when the vehicle 10 is in a horizontal position during freezing conditions.

[0066] Fig. 9 The separator 50 is depicted when the vehicle 10 is on an inclined surface that is inclined in a first direction (e.g., the front of the vehicle 10 faces a downward slope). In this first inclined position, the water level 150 can be maintained at a predetermined height, such as approximately at or below the height of the vertex 110 during above freezing conditions. During freezing conditions, the water will freeze, thereby expanding the volume of the water so that the upper ice level 152 is above the height of the vertex 110. It is observed that even during freezing conditions, the upper ice level 152 is still below the top of the outlet hole 134 in the first inclined position. In this way, water can still be removed from the separator 50 by actuating the plunger of the discharge valve 68 even during freezing conditions when the vehicle 10 is in the first inclined position.

[0067] Fig.10 The separator 50 is depicted when the vehicle 10 is on an inclined surface that is inclined in a second direction opposite to the first direction (e.g., the front of the vehicle 10 faces an upward slope). In this second inclined position, the water level 150 can be maintained at a predetermined height, such as approximately at or below the height of the vertex 110 during above freezing conditions. Under freezing conditions, water will freeze, thereby expanding the volume of the water so that the upper ice level 152 is above the height of the vertex 110. It is observed that even under freezing conditions, the upper freezing point 152 is still below the top of the outlet hole 134 in the second inclined position. In this way, water can be removed from the separator 50 by actuating the plunger of the discharge valve 68 even during freezing conditions when the vehicle 10 is in the second inclined position.

[0068] Although the exemplary embodiments are described above, it is not meant that these embodiments describe all possible forms included in the claims. The words used in the specification are descriptive words rather than limiting, and it should be understood that various changes can be made without departing from the spirit and scope of the present disclosure. As mentioned above, the features of each embodiment can be combined to form further embodiments that the present invention may not clearly describe or illustrate. Although each embodiment may have been described as providing advantages or being superior to other embodiments or prior art implementations in terms of one or more desired characteristics, it should be recognized by those of ordinary skill in the art that, according to specific applications and implementations, one or more features or characteristics may be compromised in order to achieve the desired overall system properties. These properties may include, but are not limited to, cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, maintainability, weight, manufacturability, ease of assembly, etc. Therefore, embodiments described as being less desirable than other embodiments or prior art implementations in one or more characteristics are not outside the scope of the present disclosure and can be expected to be used in specific applications.

Claims

1. A vehicle comprising: High voltage bus; an electric motor electrically connected to the high voltage bus; and A fuel cell system is electrically connected to a high voltage bus, wherein the fuel cell system comprises: fuel piles; a reservoir in fluid connection with the fuel stack, wherein the reservoir has a concave bottom wall extending upwardly into a cavity of the reservoir and forming an apex within the cavity of the reservoir, wherein the reservoir further comprises a valve receiver extending from a side wall of the reservoir into the cavity of the reservoir, wherein the valve receiver defines a drain aperture and an outlet aperture, wherein the outlet aperture has a bottom edge disposed proximate the apex of the bottom wall; a discharge pipe in fluid communication with the discharge hole; A solenoid valve is disposed in the valve receiving portion and is adapted to control fluid communication between the outlet hole and the discharge hole.

2. The vehicle according to claim 1, wherein: The fuel cell system includes an anode side, a cathode side, and a membrane disposed between the anode side and the cathode side.

3. The vehicle according to claim 2, wherein: The reservoir includes an inlet adapted to receive a fluid mixture of hydrogen, nitrogen, and water from an output of the anode side of the fuel stack.

4. The vehicle according to claim 1, wherein: At least a portion of the concave bottom wall extends upwardly into the cavity of the reservoir at an angle of between 15 and 25 degrees relative to a horizontal plane extending between the bottom edges of the side walls of the reservoir.

5. The vehicle according to claim 1, wherein: At least a portion of the valve receiving portion protrudes through the concave, tapered bottom wall.

6. The vehicle according to claim 1, wherein: At a first vehicle inclination in a first inclination direction, the water level is maintained at a predetermined height close to an apex of the bottom wall.

7. The vehicle according to claim 6, wherein: At a second vehicle inclination in a second inclination direction opposite to the first inclination direction, the water level is maintained at a predetermined height close to the apex of the bottom wall.

8. A fuel cell system comprising: fuel piles; and A reservoir is fluidically connected to the fuel stack, the reservoir having a concave conical bottom wall forming an apex within a cavity of the reservoir, the reservoir also comprising a valve receiving portion extending into the cavity of the reservoir, the valve receiving portion defining a discharge hole and an outlet hole, the outlet hole having a bottom edge arranged at the apex of the bottom wall.

9. The fuel cell system according to claim 8, wherein: The valve receiving portion is a tubular valve receiving portion extending into the cavity of the reservoir.

10. The fuel cell system according to claim 9, wherein: The valve receiver includes an abutment surface disposed within the cavity of the reservoir between longitudinal walls of the tubular valve receiver, and wherein the abutment surface defines the outlet aperture.

11. The fuel cell system according to claim 8, wherein: The concave, tapered bottom wall extends upwardly into the cavity of the reservoir at an angle of between 15 and 25 degrees relative to a horizontal plane extending between the bottom edges of the side walls of the reservoir. 12 . The fuel cell system according to claim 8 , further comprising a control valve disposed in the valve receiving portion and adapted to control fluid communication between the outlet hole and the exhaust hole.

13. The fuel cell system according to claim 8, wherein: The outlet aperture extends in a plane that is orthogonal to the plane defined by the discharge aperture.

14. The fuel cell system according to claim 8, wherein: The exit hole is circular.

15. The fuel cell system according to claim 8, wherein: The exit aperture is triangular shaped and is oriented such that a first corner and a second corner of the triangular shaped exit aperture are disposed above a third corner of the triangular shaped exit aperture.

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