Dynamic air flow control in fuel cell systems

Abstract

The present invention discloses various aspects of a method for controlling airflow to a fuel cell stack and a cooling fan within a housing, by dynamically adjusting the airflow to at least one of the fuel cell stack and the fan by connecting a predetermined minimum volume of airflow through the housing to the fan and a series of grilles, adjustable orifices and bypass valves to provide the fan with the required minimum volume of fluid during different controller-based operating modes.

Description

Technical Field

[0001] The present invention generally relates to apparatus and methods for controlling and evenly distributing the volume of air through an air-cooled fuel cell stack. Background Art

[0002] Conventional electrochemical fuel cells convert fuel and oxidant into electrical energy and reaction products. Common types of electrochemical fuel cells include membrane electrode assemblies (MEA), which include polymer ion (proton) transfer membranes between anode and cathode flow paths or gas diffusion structures. Fuels, such as hydrogen and oxidants, such as oxygen from air, pass through the corresponding sides of the MEA to produce electrical energy and water as reaction products. A stack including a plurality of such fuel cells can be formed, which is arranged with separate anode and cathode fluid flow paths. This stack is generally in the form of a block, which includes a plurality of individual fuel cell plates held together by end plates at either end of the stack. This fuel cell can be used to provide power for various technologies, such as material handling equipment (MHE) and fixed power applications and unmanned aerial vehicles (UAV).

[0003] It is important that the polymeric ion transfer membrane remains hydrated for efficient operation. It is also important to control the temperature of the stack. Therefore, a coolant may be supplied to the stack for cooling and / or hydration. It may be necessary to purge the coolant, contaminants, or reaction byproducts in the flow path or gas diffusion structure of the fuel cell using a purge gas at specific times or periodically. A purge gas, which may include a fuel, such as hydrogen, may flow through the anode flow path to purify the fuel cell.

[0004] In an air-cooled fuel cell system, one technique for regulating the fuel cell stack includes "stack pulsing" or "fan pulsing" in which the air flow to the cathode of the fuel cell stack is periodically shut off or significantly restricted so that the cathode is starved of oxygen and the stack is discharged at a high current through a load resistor so that energy dissipation occurs during this airflow restriction period.

[0005] Air-cooled fuel cell stacks can be very sensitive to cathode air flow. A small amount of air movement through the cathode air flow path is still enough for the stack to produce significant power. The more excess air there is, the harder it is to fan pulse. Therefore, it would be desirable to achieve highly restricted air flow during fan pulses. For example, fan pulses can fail when the efficiency of blocking air flow is inefficient.

[0006] Air-cooled fuel cell systems traditionally limit cathode air flow by reducing fan speed or partially closing the flow path for operation in colder conditions. These solutions negatively affect the distribution of cathode flow through the stack, resulting in temperature variations and, therefore, poor stack performance. Partial closure when in a partially open position results in turbulence, resulting in path variations. This in turn makes it impossible to finely control low-volume cathode flow. The minimum required air flow for the fan results in inefficient cooling and poor stack performance. Summary of the invention

[0007] Aspects of the gas flow control disclosed herein relate to systems, structures, and methods that direct gas flow in a desired pattern to control the routing and delivery of gas flow in a fuel cell system.

[0008] The above needs are met by various aspects of the coolant distribution system, fuel cell power system, and methods used throughout the present application. According to some aspects of the present disclosure, a method of providing airflow to a fuel cell stack and a cooling fan in a housing is taught, the method comprising: placing the fuel cell stack in fluid communication with the fan, both of which are located in the housing; connecting a predetermined minimum volume of airflow through the housing fluid to the fan by one or more of the following modes;

[0009] A. restricting airflow to an air inlet face of a fuel cell stack by diverting a portion of airflow from the fuel cell stack through a bypass assembly, the bypass assembly being located downstream of the fuel cell stack;

[0010] B. diverting a portion of the airflow from the air inlet face via a bypass assembly and reducing the airflow from the cathode exhaust of the fuel cell stack by closing one or more grilles placed between the cathode exhaust and the fan;

[0011] C. regulating airflow from an exhaust face of a cathode of the fuel cell stack to a fan via closing the grille and closing an aperture through at least a portion of the grille;

[0012] D. Open the bypass valve and open the grille, thereby providing airflow to both the inlet face and the fan;

[0013] E. opening the bypass valve, closing the grille, and one of: closing the aperture and closing at least a portion of the aperture through the grille; and

[0014] F. Close the bypass valve and do one of the following: open or close the grille.

[0015] In some cases, each grille is configured to be closed via a magnetic clamp in the housing. In some cases, each grille is composed of two plates, each plate including an orifice, wherein the plates are configured to be nested together, and when the grille is closed, the orifice is adjusted from closed to fully open via a controller by sliding one plate relative to the other plate via the action of a cam. In some cases, at least one of the two plates has a surface coating facing the other plate, and the plate is configured to have greater lubricity than an uncoated plate. In some cases, the orifice is an elongated horizontal oval. In some cases, at least a portion of the orifice is an isosceles trapezoid. In some cases, the method also includes a convex portion formed in the housing closest to the air inlet surface, and the convex portion adds turbulence to the airflow entering the air inlet surface. In some cases, the method also includes forming an airflow interruption finger-shaped member adjacent to the gas inlet surface of the fuel cell stack, wherein the linear flow of the incoming gas entering the fuel cell stack is made more turbulent.

[0016] In some cases, the fan is placed upstream of the fuel cell stack. In some cases, the fan is placed downstream of the fuel cell stack. In some cases, the bypass valve is placed downstream of the fuel cell stack. In some cases, the bypass valve is placed upstream of the fuel cell stack. In some cases, the fan is placed upstream of the fuel cell stack and the fluid control assembly is placed downstream of the fuel cell stack.

[0017] According to some aspects of the present disclosure, a system and method for regulating airflow to a fuel cell stack within a housing includes: a partially open housing configured to accommodate at least one fluid channel, a fuel cell stack, a fan, and a fluid control component, and to provide airflow; the fluid control component includes at least one bypass valve and at least one grille, the grille having an adjustable orifice formed through the grille; a controller; wherein the fluid channel is fluidly connected to the fluid control component; wherein the controller controls at least one of closing or opening of the bypass valve, the grille, and the orifice; and wherein control of the volume of air flowing to the fan and the fuel cell stack is adjusted based on the operating mode.

[0018] In some cases, the bypass motor controls the opening and closing of the bypass vent. In some cases, the controller includes a grille control assembly that controls the movement of the grille and the opening or closing of the aperture. In some cases, the grille control assembly controls the movement of the grille and the opening or closing of the aperture, and the bypass motor controls the opening and closing of the bypass vent. In some cases, the grille control assembly also includes a drive shaft that passes through each grille and is connected to a cam that is fixed to the grille. In some cases, the lower drive section is fixed to the drive shaft; the upper drive section is movably attached to the drive shaft between the lower drive section and the drive shaft guide; the spring is movably fixed to the drive shaft between the upper drive section and the drive shaft guide; thereby, the nested plate moves up or down relative to the second nested plate via the cam and the spring.

[0019] In some cases, the first surface of at least one of the nested plates is polished to reduce roughness. In some cases, the first surface of at least one of the nested plates is coated to reduce roughness and increase lubricity. In some cases, the grid control assembly is further configured to regulate at least one of an oxygen flow to the fuel cell stack and a dilution purge flow from the fuel cell stack.

[0020] According to some aspects of the present disclosure, methods and systems of fluid control assemblies include a flow control housing, the flow control housing also including a fan duct, a magnetic holder, a grille control assembly, a grille configured with a variable orifice, at least one bypass duct, at least one bypass valve, a bypass motor, and the bypass duct is fluidically connected to the flow control housing.

[0021] In some cases, the grille is formed by two sliding nested plates, each of the sliding nested plates having an aperture aligned in a first position and having a variable opening when they are displaced and an opening that is closed when they are fully displaced. In some cases, the grille control assembly controls the movement of the grille and the opening or closing of the aperture. In some cases, the grille control assembly controls the movement of the grille and the opening or closing of the aperture, and the bypass motor controls the opening and closing of the bypass vent, which is configured to open and close the flow of fluid through at least one bypass duct. In some cases, the grille control assembly also includes a drive shaft that passes through each grille and is connected to a cam that is fixed to the grille.

[0022] In some aspects, the system may include one or more sensors therein. The one or more sensors may be configured to detect a parameter of the system. In some aspects, the sensor may be configured to detect the temperature of the fuel cell and / or fuel cell stack, the temperature of the coolant entering the system, the temperature of the coolant after the coolant fluid has been discharged from the system, the pressure of the coolant fluid, the flow rate of the coolant fluid, the composition of the coolant fluid, the speed of the coolant fluid when it is discharged from the exhaust port, or another parameter of the coolant fluid or the fuel cell stack.

[0023] In some aspects, the device for directing coolant flow can operate based on various parameters, such as, but not limited to (to the extent they exist in a specific embodiment), the size or shape of the fuel cell stack, the distance between the fuel cell stack and the device for directing coolant flow, the number of fuel cells in the fuel cell stack, the number of fuel cell stacks in the system, the relative arrangement of each fuel cell stack, the material of the device for directing coolant flow, the texture of the device for directing coolant flow, the rate at which the coolant flows through the system, the composition of the coolant, the temperature of the fuel cell stack, the desired temperature of the fuel cell stack, the desired application of the system, any combination of the foregoing parameters and / or any other suitable parameters that could affect the coolant distribution requirements.

[0024] According to another aspect of the present disclosure, a fuel cell system includes a fuel cell stack having one or more fuel cells therein and a system for distributing a coolant fluid.

[0025] The system for distributing coolant fluid can be any one or more of the above-described systems, or can be a combination of the embodiments described herein. The system can include none, one or more of the optional aspects described herein.

[0026] In some aspects, the fuel cell system can be configured to provide power to a machine handling equipment (MHE) component.Alternatively, the MHE component can be a forklift.

[0027] In some aspects, the fuel cell system can be configured to provide power to an unmanned aerial vehicle (UAV). Optionally, the UAV can be a drone. The drone can be a fixed-wing drone. The drone can be a multi-rotor drone.

[0028] According to another aspect of the disclosure, a control system for directing coolant through a system for distributing a coolant fluid is disclosed. The control system includes a processor; a power supply; and a sensor. The control system is configured to send an operating signal to the system for distributing the coolant fluid to cause the system for distributing the coolant fluid to operate. The system for distributing the coolant flow can be any one or more of the above systems, or can be a combination of the embodiments described herein. The system can include, exclude, or include one or more of the optional aspects described herein.

[0029] The control system may include a processor; a power supply; and a sensor. The control system is configured to send an operating signal to the system for distributing the coolant to cause the system for distributing the coolant to operate.

[0030] In some aspects, the control system can be configured to communicate with a plurality of sensors. The sensors can be disposed in or on the system for distributing coolant.

[0031] Optionally, the control system can be configured to operate based on a program. The program can provide instructions for operation to the control system, and the control system can use the instructions for operation to operate the system for distributing coolant and / or the fuel cell system. Optionally, the control system can be operated by a user. The user can send one or more signals to the control system and / or the system for distributing coolant to operate the system. Optionally, the control system can be configured to operate autonomously in response to parameters sensed by one or more sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present application is further understood when read in conjunction with the accompanying drawings. For the purpose of illustrating the subject matter, exemplary aspects of the subject matter are shown in the accompanying drawings; however, the presently disclosed subject matter is not limited to the specific methods, devices, and systems disclosed. In the drawings:

[0033] Figure 1 is an external view of the systems and methods disclosed herein for controlling air flow to a fuel cell stack and a fan.

[0034] Figure 2A is a component view illustrating aspects of an exemplary embodiment of the systems and methods disclosed herein for controlling air flow to a fuel cell stack and a fan.

[0035] Figure 2B and Figure 2C Shows Figure 2A Various aspects of fluid control components.

[0036] Figures 3 to 4B Aspects of exemplary embodiments are shown that demonstrate adjustable airflow of the systems and methods disclosed herein.

[0037] Figure 4C Air disrupting features in the inlet face are shown, and are component views illustrating aspects of exemplary embodiments of the systems and methods disclosed herein for controlling airflow to a fuel cell stack and a fan.

[0038] Figure 5 is a table of operating modes for the systems and methods disclosed herein for controlling air flow to a fuel cell stack and a fan.

[0039] 6A to 9C Aspects of exemplary embodiments are shown that demonstrate adjustable airflow of the systems and methods disclosed herein.

[0040] Fig.10 A range of orifice examples are shown.

[0041] Fig.11 An alternative example of the systems and methods disclosed herein for controlling air flow to a fuel cell stack via an air inlet upstream of a fuel cell stack and a fan configured to draw fluid through the fuel cell stack is shown.

[0042] Various aspects of the disclosure will now be described in detail with reference to the drawings, wherein like reference numerals refer to like elements throughout unless otherwise specified. DETAILED DESCRIPTION

[0043] There has previously been no practical solution for fine control of low volume coolant flow through a fuel cell stack in a small footprint for air cooled fuel cell systems. Aspects of methods, apparatus, and systems are disclosed herein that utilize air routing, coarse and fine control of air flow to provide consistent fuel cell stack operation under a variety of conditions, including but not limited to startup, hot operation, and cold or cool down operation.

[0044] In the most basic configuration, the systems and methods disclosed herein control the flow of fluid through a fuel cell stack, which is controlled via a series of grids, orifices, and bypass valves. The innovative system provides both coarse and fine regulation of fluid flow.

[0045] The fan draws air flow through the fuel cell stack, cools the stack, dilutes the exhausted hydrogen, enables the stack to operate efficiently under a variety of power requirements, and supports intermittent purging of the system to maintain membrane efficiency and, therefore, the health / integrity of the fuel cell stack.

[0046] One or more grille doors are configured to each rotate from a fully closed position through a series of positions to a fully open position, and each grille door is a multi-part having at least two nested sliding plates, whereby each door in the closed position is configured to slide one plate vertically upward or downward relative to the other and perpendicular to the cathode exhaust flow, thereby sliding a series of aligned orifices in the plate to move open, partially closed, or fully closed, thereby effectively throttling the upward or downward air flow through the closed plate. Although the orifices are shown as being elongated in the horizontal direction, this illustration is not limiting, and other orifice shapes are also within the scope of the present disclosure. The elongated shape does support a large flow volume with less movement of the sliding orifice plate, and is therefore preferred in some cases because it at least supports smaller systems and / or higher flows.

[0047] Figures 1 to 2CThe main aspects of the fuel cell air distribution device and system 10 are shown. The main housing 12 is configured with an inlet channel 14 for air to flow into the housing and an outlet 16 for fluid to flow out of the housing. Within the housing, the subassembly shown here has two side portions 20A and a position insert 22. The subassembly can be formed by fewer or more parts, and a person of ordinary skill in the art or a person skilled in the art will recognize that such design choices will remain within the scope of the present disclosure. The subassembly surrounds the fuel cell stack 100 at one end, the fan 200 at the opposite end, and downstream of the fuel cell stack but upstream of the fan is a fluid control assembly 300, which fluidly connects the inlet channel 14 air path to the inlet face 25 for the stack through the fluid channel 24, whereby the air flow travels from the inlet channel to the fuel cell stack. The subassembly includes a fuel cell stack 100 and a fan 200 at one end, and downstream of the fuel cell stack but upstream of the fan is a fluid flow assembly 300. The fluid control assembly is a base that both connects the cathode exhaust to the fan and controls the airflow into and out of the fuel cell stack. The flow control housing 302 provides a fan duct 304 and at least one bypass duct 306, the fan duct 304 supports a magnetic holder 305 to hold the grille door in a closed position. Each bypass duct accommodates a valve 308, which can be opened or closed via a control arm 310 attached to a bypass motor 312 and controlled by a controller. The orifice grille door 320 is movably fixed to the flow control housing. Each door is formed by two plates. The first door is composed of nested plates 321A and 321B. Each plate has a first surface 401A and a second surface 401B. Each plate has an elongated orifice 400A and 400B formed therethrough, and the orifices 400A and 400B can be aligned. The second door is composed of nested plates 323A and 323B, and each plate has an elongated orifice 402A and 402B formed therethrough, and the orifices 402A and 402B can be aligned. The nested panels should fit tightly to minimize fluid leakage, and at least one of the nested doors should have sufficient lubricity to slide vertically up and down against the other door. The grille control assembly 330 is secured to each set of nested doors via a drive shaft 333, which is fitted to a guide formed to pass through the pair of nested doors. The drive motor 334 is part of the grille control assembly. The drive shaft 333 is driven by a gear connection shown in the grille control assembly. The gear assembly is not limiting, and a variety of devices are known in the art to rotate a shaft or a pair of shafts via gears and motors. The through guide 336 is not part of the rotation or movement of the door, and the drive shaft is connected to the grille door via a cam, which is used to rotate the door open or closed. The magnet 305 stops the door in the fully closed position ( Figure 6B). Means whereby a magnet stops the movement of the grille, other means such as a ball plunger, and other latches and catches are within the scope of the present disclosure. Preferably, rotation of the drive shaft after closing will adjust the aperture from open to partially open to closed. Figure 2C , Fig. 7A and Figure 7B The nested plates (321A / 321B and 323A / 323B) forming the grille doors 321 and 323 are shown. Each door is movably connected to the drive shaft 333 via a cam 500. The cam has a lower drive section 502A fixed to the drive shaft and an upper drive section 502B fixed to the nested plates, which will be driven upward and downward relative to the flow control housing 302. The drive shaft extends through a spring device 325, which is placed between the cam 500 and the grille guide 327. When the sliding plate is moved upward by the cam action, it compresses the spring, and when the cam action lowers the sliding plate, the spring decompresses and moves the sliding plate downward to align with the aperture. Fig. 7A The elongated aperture 400A through the first nested plate of the grille door 321 is shown to be misaligned with the elongated aperture 400B in the second nested plate of the grille door 321, because in this configuration, the elongated apertures block fluid flow through the grille door. As the drive shaft 333 rotates, the lower drive segment 502A of the cam moves downward to close the gap 504 between the upper drive segment and the lower drive segment, as shown in FIG. Figure 7B As shown, and the elongated orifices 400A and 400B are aligned to allow fluid flow, and the spring device forces the sliding plate downward during the rotation of the cam. In addition, the grille door is controlled by a moving device (shown here as a stepper motor 334), and the moving device causes the gear 335 to rotate the shaft in a coordinated manner. In some cases, the motor controller communicates signals with the moving device. In other cases, the motor control is combined in the system controller. If there is a motor control, it communicates signals with the system controller, thereby adjusting the position of the grille door and the elongated orifice. The system controller is configured to adjust the bypass valve, the grille door and the orifice in response to the measurement in the system or the condition of the system. The measurement via the sensor 425 includes but is not limited to one or more of power requirements, temperature, pressure, humidity, hydrogen concentration in the exhaust, stop, fan pulse and purge. The sensor communicates signals with the system controller and can be placed anywhere in the system, and the indication of the sensor 425 near the inlet surface 101 of the fuel cell stack, near the fluid control assembly and near the fan is not limited.

[0048] Figures 3 to 4B shows the overall upper edge Figure 1A cross-sectional top view looking down the line at AA in FIG. Only a block structure showing the main components is provided, and these figures show the airflow during different states of the system. Not all states are shown. Some states go through the entire range from fully closed with 0% orifice open to 100% open, including all partial openings within the range. For simplicity, only a fully open grille, a fully closed grille with a fully closed orifice, and a fully closed grille with a fully open orifice are shown, and the absence of intermediate states of partially open and partially closed orifices should not be interpreted as merely intermediate or undisclosed inventions. Figure 4C The exterior of the assembled subassembly and the air interrupting fingers formed thereon are shown.

[0049] A method of operating a fuel cell power system is disclosed herein, wherein a minimum volume airflow is maintained for operating a fan 200 by means of control of airflow via a grille, a bypass valve, and an orifice. During operation, the fan moves a minimum volume of air through the system even at low RPMs, and through the airflow dynamic control disclosed herein, when the airflow demand through the fuel cell stack is less than the minimum airflow demand of the fan, the system controller engages at least one of the bypass valve and the grille to direct the airflow while maintaining the necessary minimum airflow. If the fan is able to be less than the minimum airflow, the fan will be subject to an increased load, thereby reducing the efficiency of the system and increasing parasitic losses. The airflow diverted by the fluid flow assembly 300 is controlled by the controller.

[0050] A fluid flow including atmospheric air enters the system via the inlet passage 4 into the fluid passage 24 which is also connected to the fuel cell stack fluid. The fluid flow assembly 300 also provides for the grille to go from a fully open position to a fully closed position in a short period of time. The rapid opening and closing of the door is combined with the bypass valve and ducting to provide at least the necessary minimum volume of air to the fan under various conditions and provide the required volume of airflow to the first face 101 of the fuel cell stack, and this is dynamic and responsive to the system sensor 425. The airflow from the fluid passage 24 is directed while bypassing the fuel cell stack and the door. Figure 5 is a table illustrating operating states, operating modes, coordination of opened and closed grille doors with opened and closed orifices therein, and opening and closing of a bypass valve configured to be operated by at least one controller.

[0051] During high temperature operation (see Figure 4A and Figure 5), the bypass valve 308 is closed, and the airflow through the fluid channel is not interrupted. Instead, the airflow reaches the inlet face through the fluid channel, and the grille doors 321 and 323 are opened to distribute the airflow from the fluid channel to one of the first face 101 and the fan 200. The aperture is in an open state because the opened grille door has a moving device for sliding of the door (321A / 321B and 323A / 323B) and is open in a stationary state.

[0052] During high temperature mode operation ( Figure 4A ), the maximum volume of fluid reaches the first face 101 through the fluid passageway via closing the bypass valve 308, which forces at least 90% of the intake air to be drawn through the stack via the inlet face. In this mode, preferably, 95% of the fluid is drawn through the stack, and most preferably, 99% or more of the air is drawn through the stack in this mode. In this first mode, the grille is fully open, thereby creating minimal obstruction to the cathode exhaust fluid being exhausted from the system via the axial flow of the fan 200. Ideally, the same volume of air that flows into the inlet passage 14 passes through the fuel cell stack. An additional benefit of this operation is to ensure that there is a very low concentration of hydrogen in the cathode stream.

[0053] During system operation, it is also beneficial to create turbidity in the fluid flow entering the fuel cell stack. The fuel cell stack 100 has a first face 101 and a second face 102. The first face 101 is configured to be fluidically connected to the fluid channel 24 and receive air via the inlet face 25. In order to increase the dispersion of the fluid flowing in the housing 12 at an end of the housing opposite to the first face 101, a bump 400 ( Figure 3 ) to provide a Coanda effect, a phenomenon in which a jet attaches itself to a nearby surface and remains attached even when the surface bends away from the initial jet direction, thereby directing air toward the center of the first face. In some cases, air interruption fingers 405 may also be placed around the entry face to interrupt fluid flow and result in a more uniform distribution on the first face 101. When on the entry face, these flow interruption features convert the linear flow of the incoming fluid into turbulent flow before being ingested by the fuel cell stack. This helps to evenly distribute the fluid rather than just being sucked into the periphery of the stack. The interruption fingers and the Coanda effect may be used in conjunction or separately.

[0054] During low temperature mode configuration (see Figure 4B), the grille door 321 / 323 is closed, and the bypass valve 308 is opened to allow a higher volume of air to flow to the fan, through the bypass valve and then to the fuel cell stack. This configuration and method of operation enables most of the fluid in the fluid channel to be quickly discharged from the system without interacting with the fuel cell stack. In this second mode, the elongated orifices 400A and 400B in the closed grille are used to throttle the fluid, which leaves the stack as cathode exhaust, and only allows the necessary volume of incoming fluid (such as air) to flow through the fuel cell stack. The controller communicates signals with the device that moves the grille door, which can be the grille control assembly 330 and the bypass motor 312 and the bypass vent 308, and the controller is configured to coordinate the opening and closing of each to support the fuel cell stack and fan operation. The controller is also configured to change the upward or downward movement of the sliding nested doors that form the grille to change the volume of fluid passing through the orifice.

[0055] During the first medium temperature mode configuration (see Figure 5 ), the grille doors 321 / 323 are closed, and the bypass valve 308 is closed to direct the same volume of airflow to the fan and through the fuel cell stack. In this third operating mode, the elongated apertures 400A and 400B in the closed grille are used to throttle fluid that leaves the stack as cathode exhaust and only allow the necessary volume of incoming fluid (such as air) to flow through the fuel cell stack. The controller is in signal communication with the means for moving the grille doors, which is configured to change the upward or downward movement of the sliding nested doors forming the grille to change the volume of fluid passing through the apertures.

[0056] During the second medium temperature mode configuration (see Figure 5 ), the grille doors 321 / 323 are opened, and the bypass valve 308 is opened, thereby providing a larger volume of airflow to the fan than to the fuel cell stack.

[0057] FIG. 6A to FIG. 6C The basic operation of the grille doors is shown. In the high temperature mode, when maximum airflow through the fuel cell stack is required, the grille doors 321 / 323 are opened ( Fig. 6A ) and the bypass valve is closed. In one of the low and medium temperature restricted fluid flow configurations, the grille doors 321 / 323 are closed ( Figure 6B ), magnets 305 hold them in the closed position, and cam 500 is in a lowered position whereby elongated orifices 402A / 402B are aligned in the open position and configured to enable maximum fluid volume to flow through the aligned orifices. Figure 6CShown is a top view of the flow control housing 302 and the cooperating gears that form the means to both open and close the grille and slide one of the nested plates 321A / 321B and 323A and 323B up and down. Fig. 7A and Figure 7B Shown is a partial view of an orifice being closed and a partial view of an orifice being aligned and opened via cam movement. FIG. 8A to FIG. 8C Aperture operation and nested door configuration are shown. The grille door is shown open, section "B" is a close-up of the grille door and elongated aperture. Figure 8B An edge view in section "B" of a nested door along line "BB" is shown with coating 510 formed on first surface 401A of nested plate 321A. The coating is configured to have high lubricity (such as PTFE, ceramic, or other material that is more lubricious than the material forming the plate) to facilitate movement of the nested door against nested plate 321B. The height of the elongated orifices is "h", and when the nested plates are aligned, the orifices cooperate to form a fluid passageway of height "h". Figure 8C An edge view of an alternative set of nested panels in section "B" along line arrow "BB" is shown, wherein coating 510 is formed on a first surface of a first nested panel 321A, and coating 520 is formed on a first surface of a second nested panel 321B. The coating is configured to have high lubricity to facilitate movement of the nested door against the second nested door 321B. 9A to 9C Aperture operation and nested door configuration are shown. The grille door is shown partially closed, section "B" is a close-up of the grille door and elongated aperture. Fig. 9B A partial closure is shown. Fig. 9C An edge view of a section "B" of the nested doors along the line of arrow "CC" is shown, with the height of the elongated orifices being "h", however, when the nested doors are throttled or partially closed, the orifices cooperate to form a fluid passageway of height "h2", thereby reducing fluid flow. In this embodiment. The nested plates are not described as being coated. However, the first surface 410A of each nested plate can be coated, or it can be polished, or other surface finishing applied to reduce roughness to support smooth sliding. In addition, at least one plate can be formed of a single material with sufficient lubricity to promote smooth sliding. Fig.10 Various additional orifice shapes are shown, all of which are within the scope of the present disclosure. The displacement of a sliding plate to completely close an orifice is defined by the height "h3", which is equal to the height of a single orifice of the two orifices. The vertical orifice 602 requires a greater displacement to close than the square orifice 604 or the circular orifice 604. The elongated orifices 606 and 608 require less displacement. Our testing found that the elongated oval orifices 400A / 400B provide controllable airflow with minimal displacement.

[0058] Fig.11 A cross-sectional top view is shown showing the main components of the system and method disclosed herein for controlling airflow to a fuel cell stack and a fan via an air intake port upstream of a fuel cell stack. Figures 3 to 4B and FIG. 6A to FIG. 10 The operating modes are the same as those described in .

[0059] A fluid path is provided for air 1000 entering the system through the air inlet face 25 of the housing. Air enters the fan 200 and is blown toward the first face 101 of the fuel cell stack 100 to provide cooling therein. The fluid control assembly 300 is preferably disposed upstream of the fuel cell stack. However, in some cases, the fluid control assembly 300' may be positioned downstream of the fuel cell stack, wherein the bypass valve 308 is positioned in the bypass conduit 308 upstream of the fuel cell stack.

[0060] When the fuel cell stack is upstream of the fan, the fan will operate to draw airflow through the stack, which results in a more uniform air distribution through the stack's air inlet face 101, which then pushes the air through the stack, as shown. Fig.11 As shown. Drawing air improves the performance of the fuel cell stack by providing uniform cooling. In addition, in an air drawing configuration where the fan is located downstream of the fuel cell stack, the fan can be mounted in close proximity to the fuel cell stack outlet face 102, which results in a greater volumetric power density for the system, as opposed to an air push embodiment, where the fuel cell stack is placed downstream of the fan so that the airflow from the fan is pushed into the first face 101 (inlet face) of the fuel cell stack.

[0061] exist Fig.11 In, a configuration for pushing air is shown, and as opposed to drawing (or sucking) air through the system, this embodiment has the advantage of maximizing fan efficiency. The air pushes the fan device to move cold ambient air without moving air that has been heated when the air passes through the fuel cell stack. Colder air is moved under a given volume due to its higher density, resulting in a greater mass of air provided to the fuel cell stack, and therefore greater cooling potential can be obtained. However, when the air 1000 is pushed to the first face 101, there is a less uniform air distribution without adding a complex structure to smooth the airflow or forming a large distance between the fuel cell stack and the fan. If there is a relatively large distance between the stack and the fan, this increases the minimum volume of the entire system and means that a poor volume power density is achieved relative to the system.

[0062] The system described throughout the present disclosure can be utilized in various applications for providing electricity generated by fuel cells. In some aspects, the system disclosed throughout the present application can be used for machine handling equipment (MHE), such as forklifts. In some aspects, the system can be used in unmanned aerial vehicles (UAVs), such as fixed-wing or multi-rotor drones. In some aspects, the system disclosed herein can be used in automotive applications, such as in automobiles. It should be understood that the system can be used in various other applications, and certain functional and physical parameters, such as component size and quantity, can vary for specific applications and can be specified according to the needs of specific uses. Additional advantages of the above include the ability to fit the system and related components (such as fuel tank cylinders) into a smaller space, and the ability to arrange the system and related components.

[0063] The components disclosed herein may utilize known materials used in the industry.

[0064] Throughout this specification, words should be given their normal meanings as understood by those skilled in the relevant art. However, in order to avoid misunderstanding, the meanings of certain terms will be specifically defined or clarified.

[0065] Although the present disclosure has been described in conjunction with the various embodiments of the various drawings, it will be appreciated by those skilled in the art that changes may be made to the above embodiments without departing from the broad inventive concept thereof. Therefore, it should be understood that the present disclosure is not limited to the specific embodiments disclosed, and it is intended to cover modifications within the spirit and scope of the present disclosure as defined by the claims.

[0066] In a single embodiment, the features of the present disclosure described above in the context of separate embodiments may be provided in combination. Conversely, various features of the present disclosure described in the context of a single embodiment may also be provided individually or in any sub-combination. Finally, while an embodiment may be described as part of a series of steps or part of a more overall structure, each described step may also be considered an independent embodiment in itself, capable of being combined with other steps.

[0067] Unless otherwise indicated herein, recitation of ranges of values ​​herein are merely intended as a shorthand method of referring individually to each separate value falling within the range, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context.

Claims

1. A method for providing airflow to a fuel cell stack and a cooling fan in a housing, the method comprising: placing a fuel cell stack in fluid communication with a fan, the fuel cell stack and the fan both being located within the housing; fluidly connecting a predetermined minimum volume of airflow to the fan through the housing in one or more of the following modes; A. regulating airflow from the fuel cell stack cathode exhaust face to the fan by closing the grille and closing at least a portion of the apertures through the face of the grille; B. opening the bypass valve, closing the grille, and one of: closing the apertures through the face of the grille and closing at least a portion of the apertures through the face of the grille; and Wherein each grille is comprised of two plates, each plate including an aperture, wherein the plates are configured to nest together and when the grille is closed, the aperture is adjusted from closed to fully open via a controller by sliding one plate relative to the other via the action of a cam.

2. The method according to claim 1, wherein: Each grille is configured to be closed via a magnetic catch in the housing.

3. The method according to claim 1, wherein: At least one of the two plates has a surface coating thereon facing the other plate, the at least one plate being configured to have greater lubricity than an uncoated plate.

4. The method according to claim 1, wherein: The orifice is an elongated horizontal oval.

5. The method according to claim 4, wherein: At least a portion of the apertures is an isosceles trapezoid.

6. The method of claim 1, further comprising forming a convex portion on an inner side of the housing closest to an air inlet face, the convex portion adding turbulence to an air flow entering the air inlet face.

7. The method of claim 1 further comprising forming an air flow interruption finger adjacent to an air inlet face of the fuel cell stack, wherein: The linear flow of intake air into the fuel cell stack becomes more turbulent.

8. The method of claim 1, wherein: The fan is positioned downstream of an exhaust of the fuel cell stack; and, A flow control assembly is configured to vary the volume of airflow drawn through the fuel cell stack by the fan.

9. A fluid control assembly comprising: The flow control housing (302) further comprises: Fan duct (304); Magnetic clamp (305); A grille control assembly (330); a grille formed of two sliding nested plates (321A / 321B) configured to have variable apertures therein, each of said sliding nested plates having apertures (402A and 402B) aligned in a first position and having variable openings when they are displaced and openings that are closed when fully displaced; at least one bypass conduit (306); at least one bypass valve (308); Bypass motor; wherein the bypass conduit is fluidically connected to the flow control housing; and wherein the grille control assembly (330) controls the opening or closing of the aperture through the face of the closed grille.

10. The fluid control assembly of claim 9, wherein: The grille control assembly (330) controls the movement of the grille and the opening or closing of the aperture.

11. The fluid control assembly of claim 9, wherein: A grille control assembly (330) controls movement of the grille and opening or closing of the aperture, and a bypass motor (312) controls opening and closing of a bypass vent configured to open and close fluid flow through the at least one bypass duct.

12. The fluid control assembly of claim 10, wherein: The grille control assembly (330) also includes a drive shaft (333) that passes through each grille and is connected to a cam that is fixed to the grille.

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