CN113258116A - Fuel cell stack and fuel cell system - Google Patents
Fuel cell stack and fuel cell system Download PDFInfo
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- CN113258116A CN113258116A CN202110491114.0A CN202110491114A CN113258116A CN 113258116 A CN113258116 A CN 113258116A CN 202110491114 A CN202110491114 A CN 202110491114A CN 113258116 A CN113258116 A CN 113258116A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/24—Grouping of fuel cells, e.g. stacking of fuel cells
- H01M8/241—Grouping of fuel cells, e.g. stacking of fuel cells with solid or matrix-supported electrolytes
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
- H01M8/04291—Arrangements for managing water in solid electrolyte fuel cell systems
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/24—Grouping of fuel cells, e.g. stacking of fuel cells
- H01M8/2457—Grouping of fuel cells, e.g. stacking of fuel cells with both reactants being gaseous or vaporised
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/24—Grouping of fuel cells, e.g. stacking of fuel cells
- H01M8/2465—Details of groupings of fuel cells
- H01M8/2483—Details of groupings of fuel cells characterised by internal manifolds
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
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Abstract
The invention discloses a fuel cell stack and a fuel cell system, wherein the fuel cell stack comprises a plurality of bridge holes and a common flow passage, the fuel cell stack also comprises a pulse exhaust mechanism, the pulse exhaust mechanism is arranged in the common flow passage where a hydrogen outlet is positioned, the pulse exhaust mechanism comprises a flow baffle, at least one exhaust groove is arranged on the side wall of the flow baffle, the exhaust groove penetrates through the side wall of the flow baffle, and the exhaust groove can move along the extension direction of the common flow passage, so that the bridge holes at the hydrogen outlet of a single cell can be switched between gas closing and gas exhausting, a single cell can realize pulse type flow change, and the generated short-time large flow is favorable for discharging liquid water in the single cell. The plurality of exhaust grooves periodically and repeatedly sweep the whole battery pack in the fuel cell stack, so that each single battery sequentially executes hydrogen pulse exhaust action along the stacking direction, the requirement of stack hydrogen drainage on hydrogen metering ratio is reduced, and the technical difficulty and energy consumption of a hydrogen circulation system are further reduced.
Description
Technical Field
The invention relates to the field of fuel cells, in particular to a fuel cell stack and a fuel cell system.
Background
With the technological innovation of proton exchange membrane fuel cells, researchers are continuously developing fuel cell stacks with higher volumetric power densities, and the operating current densities thereof are also higher and higher. In the process, the proton exchange membrane technology plays a key role, the proton exchange membrane with thinner thickness and higher conductivity is developed and widely applied on the basis of keeping the mechanical strength and durability of the membrane, the lower ohmic loss caused by the proton exchange membrane technology enables the electric pile to operate at higher current density to obtain higher peak power, and meanwhile, the higher water diffusion speed enables the water generated by the reaction to be rapidly diffused in the membrane electrode, so that the necessity of an external humidifier is omitted, and the cost of a power generation system is saved.
However, the higher the current density of the fuel cell stack operation, the more water is generated during the operation, and thus, the problem of smoothly discharging a large amount of generated water generated by the fuel cell stack is becoming one of the main problems in the current stack development. If water accumulation or water flooding exists in a certain single cell of the electric pile, the performance of the whole electric pile is influenced, more harsh operating conditions are needed to maintain stable operation, parasitic energy consumption of the system is increased, and serious current distribution difference is generated, so that local overheating or electrode reversal is caused, electrode materials are damaged, the service life is shortened, and even the electric pile is damaged. Although water is generated at the cathode in the fuel cell, the highly diffusive membrane can permeate a large amount of generated water to the anode. The relatively lower flow rate and inertia of hydrogen in a fuel cell makes it less capable of bringing out water, thereby causing an increasingly frequent flooding problem in thin film high power fuel cells, which is also more hazardous than cathode flooding on the air side.
Currently, fuel cell anode drainage mainly depends on the combined application of hydrogen circulation and pulse exhaust. The hydrogen circulation process is to use the unreacted hydrogen flowing out from the outlet of the fuel cell stack to remove the liquid water, then the unreacted hydrogen returns to the hydrogen inlet through parts such as an air pump or an ejector and the like, and the unreacted hydrogen is mixed with the fresh hydrogen and then enters the stack to achieve the recycling of the hydrogen, so that the fuel utilization rate (generally > 95%) is improved, the hydrogen supply metering ratio of the stack is improved, the hydrogen with relatively higher flow rate flows through the stack, and the discharge of the liquid water migrating from the cathode is accelerated. The pulse exhaust is pulse switching of valve exhaust/gas closing arranged at the hydrogen outlet of the galvanic pile, generates large-flow exhaust in a very short time on the basis of wasting hydrogen fuel as little as possible, and quickly exhausts the waste gas and liquid water accumulated in the galvanic pile or a water separator. Through the combined application of hydrogen circulation and pulse exhaust, the metering ratio of the hydrogen circulation and the pulse frequency and time of the exhaust are jointly adjusted, so that the drainage of the hydrogen cavity and the utilization rate of the hydrogen can be optimally considered. The combination of hydrogen circulation and pulsed exhaust has become the mainstream application of today's high power fuel cell systems. The larger the hydrogen circulation flow is, the higher the hydrogen metering ratio is, and the larger the hydrogen flow rate in the cell flow field is, so that the uniformity of the reaction gas concentration is favorably improved, and the discharge of liquid water in the hydrogen cavity is also favorably realized. However, the higher flow of water vapor saturated hydrogen gas circulating through the fuel cell will generate significantly increased pressure loss, and this high flow and high head pumping requirement will significantly increase the technical difficulty and cost of the hydrogen reflux pump or ejector, as well as increase parasitic energy consumption, resulting in a reduction in the net output of the system. Therefore, in the aspect of matching and controlling of the current fuel cell system, developers adopt lower hydrogen circulation flow as much as possible on the premise of avoiding hydrogen shortage or flooding; in the design and development of fuel cell stacks, one of the main directions of developers is to design bipolar plate flow fields and stack structures with stable operation capability at lower hydrogen metering ratio.
Disclosure of Invention
The invention aims to solve the technical problem that the fuel cell stack in the prior art is difficult to reduce the backflow flow of hydrogen due to water drainage limitation, and provides a fuel cell stack design and a fuel cell system.
The invention solves the technical problems through the following technical scheme:
a fuel cell stack comprises a plurality of bridge holes and a common flow channel, and is characterized by further comprising a pulse exhaust mechanism, wherein the pulse exhaust mechanism is arranged in the common flow channel where a hydrogen outlet is located, the pulse exhaust mechanism comprises a flow baffle plate, the side wall of the flow baffle plate is provided with at least one exhaust groove, the exhaust groove penetrates through the side wall of the flow baffle plate, and the exhaust groove can move along the extending direction of the common flow channel so as to enable a single cell in the stack to be switched between an air-closed state and an exhaust state;
when the flow baffle plate shields the bridge hole, the single battery corresponding to the bridge hole is in a gas-closed state;
when the exhaust groove is communicated with the bridge hole, the single battery corresponding to the bridge hole is in an exhaust state.
In the scheme, a pulse exhaust mechanism is arranged in a common flow channel where a hydrogen outlet is located, wherein a flow baffle is used for shielding a bridge hole in the fuel cell, which is communicated with the common flow channel where the hydrogen outlet is located, so that the bridge hole serving as the hydrogen outlet of a single cell is closed, and the corresponding single cell is in a hydrogen gas closed state; the flow baffle is provided with an exhaust groove, so that the bridge hole on the bipolar plate can be exposed from the exhaust groove and communicated with the common flow channel, and the discharge of the excessive hydrogen in the corresponding single battery is realized, so that the corresponding single battery is in an exhaust state. When the exhaust groove moves in the extending direction of the common flow channel and repeatedly passes through a bridge hole at the hydrogen outlet side of a certain single battery, the pulse type flow change of the hydrogen of the single battery can be realized, the generated short-time large flow is favorable for the discharge of liquid water in the single battery, and the requirement of the hydrogen flow channel for water discharge on the hydrogen metering ratio is favorable.
By adopting the structural form, the whole battery pack formed after a plurality of single batteries are stacked is matched, and the exhaust groove of the exhaust mechanism is operated to sweep the hydrogen outlet bridge hole of the whole battery pack, so that each single battery can sequentially execute the switching actions of hydrogen gas closing, exhaust and closing along the stacking direction; the exhaust slot is further operated to periodically and repeatedly sweep the entire stack so that each individual cell sequentially performs a hydrogen pulse exhaust action in the stacking direction. From the macroscopic view of the fuel cell stack, the exhaust mechanism can reduce the requirement of hydrogen discharge of the stack on the hydrogen metering ratio on the basis of keeping the hydrogen flow and the pressure of the fuel cell stack relatively stable, thereby reducing the technical difficulty, the cost and the energy consumption of a hydrogen circulating system.
Preferably, along the extending direction of the common flow channel, a plurality of exhaust grooves are arranged on the flow baffle at intervals. The flow baffle is provided with a plurality of air discharge grooves at intervals, so that the pulse air discharge mechanism can simultaneously execute pulse air discharge actions of a plurality of single batteries. Through setting up suitable exhaust groove interval, can set for the carminative frequency of pulse, and then be favorable to reaching best exhaust and drainage effect.
Preferably, the flow baffle is a cylindrical structure with openings at two ends, the exhaust groove is spirally arranged along the side wall of the flow baffle, and the flow baffle rotates around the axis of the flow baffle. The flow baffle is arranged into a cylindrical structure with two open ends, and hydrogen discharged from the exhaust groove can be gathered from the inside of the cylinder of the flow baffle and discharged from the two ends. Offer spiral helicine air discharge duct on cylindric fender flow plate's lateral wall, when fender flow plate rotates round its axis, make spiral helicine air discharge duct produce the effect of translation in the axis direction along fender flow plate, make it carry out pulse exhaust action to each single battery in proper order along the extending direction of hydrogen export common flow channel, can not only carry out large-traffic exhaust to corresponding a plurality of single batteries in the short time, and then be favorable to the discharge of the interior liquid water of the single battery that corresponds, thereby be favorable to reducing the demand that the total hydrogen of pile compares. Moreover, by adopting the structure, the number of the single batteries for exhausting and closing the hydrogen in the fuel cell stack is kept constant in the operation process, so that the total flow and the total pressure of the hydrogen in the stack are always in a stable state, the total hydrogen flow demand of the stack is reduced, and the technical difficulty, the cost and the energy consumption of a hydrogen supply and hydrogen circulation system are reduced.
Preferably, the width of the exhaust groove is the same as the thickness of a single cell in the fuel cell stack. The width of the exhaust groove is set to be the same as the thickness of a single battery, when the exhaust groove translates to pass through the distance of the thickness of the single battery, the hydrogen discharge bridge hole of the single battery with large exhaust flow is shielded by the baffle plate, and the hydrogen discharge bridge hole of the adjacent single battery in the translation direction of the exhaust groove is exposed from the exhaust groove, so that the hydrogen discharge bridge hole is communicated with the common flow passage of the hydrogen outlet. The width of the exhaust groove is set to be the same as the thickness of the single battery, so that the adjacent single batteries can exhaust gas with large flow rate at different time, and the exhaust efficiency of the single battery in short-time hydrogen exhaust flow rate can be improved, thereby being more beneficial to the discharge of liquid water. The continuous rotation of the flow baffle can make each single cell change between exhaust and gas closing in turn, so as to realize the effect of pulse exhaust in the cell stack.
Preferably, the pitch of the air vent groove is not less than an integral multiple of 2 of the thickness of the single battery. The screw pitches of the exhaust grooves are 2 times, 3 times and 4 times of the thickness of the single batteries …, so that all the single batteries in the exhaust state are in the same pulse phase, uniform exhaust flow is obtained, and the same exhaust and drainage efficiency is achieved.
Preferably, the pulse exhaust mechanism further includes a rotating shaft, the rotating shaft penetrates through the inner cavity of the flow baffle, is spaced apart from the flow baffle and is fixed to the flow baffle, the rotating shaft is coaxial with the flow baffle, and the rotating shaft rotates around the axis of the rotating shaft. The rotating shaft and the flow baffle plate are fixed, so that the flow baffle plate rotates along with the rotating shaft when the rotating shaft rotates. The rotating shaft and the flow baffle are arranged at intervals, so that hydrogen discharged from the exhaust groove on the flow baffle can flow out from a gap between the rotating shaft and the flow baffle. By adopting the arrangement mode, on one hand, the two ends of the flow baffle plate are favorably arranged into an open mode, so that the hydrogen is conveniently discharged, on the other hand, the rotating shaft provides rotating power for the flow baffle plate, the rotating shaft and the position of the flow baffle plate are favorably arranged, so that the whole pulse exhaust mechanism is smaller and more exquisite, and the weight and the volume of the fuel cell stack are favorably reduced.
Preferably, the pulse exhaust mechanism further comprises a plurality of connecting rods arranged at intervals, the connecting rods are uniformly distributed on the outer surface of the rotating shaft, and two ends of each connecting rod are respectively connected to the outer surface of the rotating shaft and the inner side surface of the flow baffle. The two ends of the connecting rod are respectively connected with the rotating shaft and the flow baffle plate so as to realize the relative fixed connection of the rotating shaft and the flow baffle plate. Set up through a plurality of connecting rods intervals for have the clearance between the connecting rod, be favorable to the circulation of hydrogen. And evenly distribute a plurality of connecting rods in the surface of pivot, be favorable to keeping the balance when the pivot rotates, and then be favorable to improving the stability of pulse exhaust mechanism operation.
Preferably, the pulse exhaust mechanism further comprises a motor, the rotating shaft is connected to the motor, and the motor drives the rotating shaft to rotate. The motor drives the rotating shaft to rotate, so that the reliable operation of the pulse exhaust mechanism can be ensured, and the smooth pulse exhaust of the fuel cell stack is further ensured.
Preferably, the pulse exhaust mechanism further includes a fan blade, and the fan blade is disposed at an end of the common flow channel and located at a downwind end in a flow direction of the hydrogen. The tip that corresponds at the hydrogen export sets up the flabellum to with the downwind end of the hydrogen flow direction of flabellum setting, when hydrogen from the bridge opening discharge and flow out from public runner, drive the flabellum rotatory under the effort of hydrogen air current, because the rotatory pressure differential that increases flabellum front end and rear end hydrogen of flabellum, and then can accelerate the discharge of hydrogen in the fuel cell pile, thereby be favorable to the discharge of hydrogen and liquid water in the fuel cell pile more.
Preferably, the pulse exhaust mechanism further includes a rotating shaft, the rotating shaft penetrates through an inner cavity of the flow baffle and is fixed with the flow baffle, the fan blade is connected to one end of the rotating shaft, and the fan blade is located at a downwind end in the flow direction of the hydrogen. The rotating shaft and the flow baffle plate are fixed, the fan blade is arranged at the downwind end, in the flowing direction of hydrogen, of the rotating shaft, the fan blade is driven to rotate under the action of hydrogen airflow, the rotating shaft is driven to rotate by the fan blade, the flow baffle plate is driven to rotate, and then the spiral exhaust groove in the flow baffle plate is enabled to translate along the axis direction of the rotating shaft, so that pulse exhaust action of a single battery is achieved. The whole process is that the fan blades are driven to rotate through the discharge of hydrogen, so that power is provided for the operation of the pulse exhaust mechanism, a driving motor is not needed to be additionally installed, the cost can be saved, and the structure can be simplified. The rotation speed of the fan blade is correlated with the hydrogen flow rate, and the hydrogen flow rate is approximately positively correlated with the output current of the fuel cell stack operation, and is further positively correlated with the water amount of the generated water. When the output current of the fuel cell stack is larger, the hydrogen flow is larger, the rotating speed of the fan blades is higher, so that the rotating speed of the rotating shaft is higher, the exhaust frequency and the air closing frequency of a single cell are higher, namely the pulse exhaust frequency is higher, the accumulation time of liquid water is favorably shortened, and the drainage effect is favorably improved.
Preferably, the pulse exhaust mechanism further includes a rotating shaft, a first gear, a second gear and a connecting shaft, the rotating shaft penetrates through an inner cavity of the flow baffle and is fixed with the flow baffle, the rotating shaft is connected with the first gear, the connecting shaft is connected with the second gear, the first gear is meshed with the second gear, the fan blades are connected to an end of the connecting shaft, and the fan blades are located at a downwind end in the hydrogen flow direction. Through being connected pivot and first gear, the connecting axle of being connected with the flabellum is connected with the second gear, and it is rotatory to drive the flabellum through the hydrogen air current, thereby the flabellum drives the connecting axle rotation and drives the second gear rotation, and first gear and second gear meshing for thereby the second gear drives first gear rotation and drives the pivot rotation, finally makes the fender among the pulse exhaust mechanism flow board and rotates. The rotating shaft in the pulse exhaust mechanism is driven to rotate through gear transmission, and the rotating speed range of the pulse adjusting mechanism can be adjusted by setting gears with different gear ratios through actual conditions.
Preferably, the common flow channel where the hydrogen outlet of the fuel cell stack is located is communicated with the hydrogen inlet of the water separator, and the fan blade is arranged at the hydrogen inlet of the water separator. The rotation of flabellum can produce centrifugal effect to liquid water, consequently, sets up the flabellum at the hydrogen entrance of water knockout drum, can carry out the primary separation with the liquid water in the hydrogen air current, has vapor-water separation's function, not only is favorable to improving the efficiency of fuel cell pile exhaust and drainage, still is favorable to improving water knockout drum gas-liquid separation's effect.
Preferably, one end of the flow baffle is provided with a rotation speed sensor, and the rotation speed sensor is used for detecting the rotation speed of the flow baffle. One end of the flow baffle is provided with a rotating speed sensor for detecting whether the flow baffle operates normally, and if the flow baffle stops, the single battery which is shielded and closed is easy to flood, so that the fuel battery needs to be stopped suddenly. Of course, the rotation speed sensor is not limited to be connected to the baffle plate, and in the present invention, the rotation speed sensor is connected to the rotating shaft.
Preferably, the flow baffle is attached to the side surface of the common flow channel corresponding to the flow baffle. The flow baffle is attached to the side surface of the common flow channel, but the flow baffle and the common flow channel are allowed to move or rotate relatively and clamping stagnation is avoided, so that the exhaust groove moves relative to the common flow channel. Through the structure, air leakage between the flow baffle and the common flow channel is minimized, the pressure in the single battery in the air-closed state can be improved, and the short-time exhaust flow is larger when the air is switched to the exhaust state, so that drainage is facilitated.
Preferably, the fuel cell stack comprises a plurality of single cells, each of which comprises a bipolar plate, a hydrogen flow channel and a common flow channel hole are arranged on the bipolar plate, and the bridge hole is arranged on the bipolar plate and communicates the hydrogen flow channel with the common flow channel hole. A plurality of single batteries are stacked to form a fuel battery pack, meanwhile, common runner holes on the single batteries are overlapped to form a common runner and are communicated with a hydrogen inlet and outlet interface of the fuel battery stack, and the bridge hole is used for communicating the hydrogen runner on the bipolar plate with the common runner hole, so that hydrogen supplied to the batteries or hydrogen which is excessive in reaction flows into the hydrogen runner from the common runner through the bridge hole or flows out of the hydrogen runner to the common runner. When the excessive hydrogen flows out, the vapor water and the liquid water generated during the reaction of the fuel cell stack are carried away.
Preferably, the fuel cell stack further includes an end plate, a collector plate, and an insulating plate, and shapes and sizes of through holes on the end plate, the collector plate, and the insulating plate, which correspond to the common flow channel where the hydrogen outlet is located, are consistent with those of the common flow channel. By adopting the arrangement mode, when the pulse exhaust mechanism is assembled and disassembled, the galvanic pile does not need to be disassembled, so that the pulse exhaust mechanism is convenient to install or maintain.
Preferably, the fuel cell stack further comprises an end cover, the end cover is connected and sealed with the through hole on the end plate through a flange, and two ends of the pulse exhaust mechanism are respectively connected to the end cover or the end plate. The end cover and the end plate are connected and sealed through the flange, the whole pulse exhaust mechanism is conveniently arranged in a module butted by the end plates, the integration degree is further improved, and meanwhile, the maintenance and the repair are convenient.
A fuel cell system characterized in that it comprises a fuel cell stack as described above.
In the scheme, the fuel cell stack is adopted in the fuel cell system, and the pulse high-flow exhaust of the single cell inside the stack is realized by using the pulse exhaust mechanism inside the stack, so that the problem of discharging liquid water accumulated in a cell flow passage is solved. And the single cell in the fuel cell stack is sequentially exhausted by utilizing the structural characteristics of the pulse exhaust mechanism, so that the pulse exhaust mechanism has the advantages of keeping the total flow and the total pressure stable, and also has the advantage of reducing the requirement of the total hydrogen metering ratio of the fuel cell stack, thereby reducing the technical difficulty, the cost and the energy consumption of a hydrogen circulating system.
On the basis of the common knowledge in the field, the above preferred conditions can be combined randomly to obtain the preferred embodiments of the invention.
The positive progress effects of the invention are as follows: the fuel cell stack and the fuel cell system have the advantages that the pulse exhaust mechanism is arranged in the common flow channel where the hydrogen outlet is located, the flow baffle is used for shielding a bridge hole at one end of the common flow channel of the hydrogen outlet of the fuel cell, and the effect of closing the hydrogen outlet of the single cell communicated with the bridge hole is generated. And the flow baffle is provided with an exhaust groove, so that the bridge hole of the bipolar plate can be exposed from the exhaust groove and communicated with the common flow channel, and the discharge of the excessive hydrogen in the corresponding single battery is realized. By designing and operating the exhaust mechanism, a plurality of equally spaced exhaust slots are periodically and repeatedly swept across the entire stack within the fuel cell stack, such that each individual cell sequentially performs a hydrogen pulse exhaust action in the stacking direction. From the macroscopic view of the fuel cell stack, the exhaust mechanism can achieve the effects of reducing the requirement of stack hydrogen drainage on the hydrogen metering ratio and further reducing the technical difficulty, cost and energy consumption of a hydrogen circulating system on the basis of keeping the hydrogen flow and pressure of the fuel cell stack relatively stable.
Drawings
Fig. 1 is a schematic view of the internal structure of a fuel cell stack according to embodiment 2 of the present invention.
Fig. 2 is a partial structural view of a fuel cell stack according to embodiment 2 of the present invention.
Fig. 3 is a front view of the internal structure of a fuel cell stack according to embodiment 2 of the present invention.
Fig. 4 is a schematic perspective view of a pulse exhaust mechanism in a fuel cell stack according to embodiment 2 of the present invention.
Fig. 5 is a front view of a pulse exhaust mechanism in a fuel cell stack according to embodiment 2 of the present invention.
Fig. 6 is a schematic perspective view of a pulse exhaust mechanism in a fuel cell stack according to embodiment 2 of the present invention from another perspective.
Fig. 7 is an enlarged schematic view of a common flow channel at a hydrogen gas outlet in a fuel cell stack of embodiment 2 of the present invention.
Fig. 8 is a schematic plan view of a fuel cell stack in a fuel cell stack according to embodiment 2 of the present invention.
Fig. 9 is a sectional view taken along line a-a of fig. 8.
Description of reference numerals:
Hydrogen inlet common flow passage 101
Hydrogen outlet common flow channel 102
Air outlet common flow passage 103
Air inlet common flow passage 104
Exhaust slot translation direction 40
Detailed Description
The present invention will be more clearly and completely described below by way of examples and with reference to the accompanying drawings, but the present invention is not limited thereto.
Example 1
The present embodiment provides a fuel cell stack, which includes a stack, an end plate, a collector plate, and an insulating plate, wherein the collector plate, the insulating plate, and the end plate are respectively disposed on two opposite sides of the fuel cell stack 10 in sequence from the fuel cell stack 10. As can be understood with reference to fig. 1-3, the fuel cell stack 10 includes a plurality of single cells 105, each single cell 105 including a membrane electrode, two bipolar plates between which the membrane electrode is positioned, and a plurality of single cells 105 stacked to form the fuel cell stack 10. The current collecting plates, the insulating plates and the end plates of the positive and negative poles are sequentially superposed on the outer side of the fuel cell stack 10 from inside to outside, and the fuel cell stack 10 is fastened and sealed by insulating fixing rods, nuts and the like to form a fuel cell stack. A hydrogen inlet common flow path 101, a hydrogen outlet common flow path 102, an air inlet common flow path 104, and an air outlet common flow path 103 are provided in the fuel cell stack 10, respectively. Correspondingly, a hydrogen supply interface and an exhaust interface which are communicated with the common flow channel, an air supply interface and an exhaust interface, a cooling liquid inlet interface and a cooling liquid outlet interface and the like are arranged on the collector plate, the insulating plate and the end plate on one side.
Specifically, a hydrogen flow channel is arranged on the side wall of the anode side of the bipolar plate, a common flow channel hole is arranged at the common flow channel corresponding to the hydrogen inlet and the hydrogen outlet, the hydrogen inlet and the hydrogen outlet are respectively communicated with the common flow channel hole through a bridge hole 1051, and the bridge hole 1051 is arranged on the bipolar plate. Each double-click plate is provided with a plurality of bridge holes, and the hydrogen flow channels on the bipolar plates are communicated with the common flow channel holes through the bridge holes so as to circulate hydrogen. A plurality of single cells 105 are stacked to form a fuel cell stack 10, and meanwhile, common flow channel holes on the single cells are stacked to form a common flow channel and are communicated with a hydrogen inlet and outlet port of the fuel cell stack, and the bridge hole 1051 is used for communicating a hydrogen flow channel on the bipolar plate with the common flow channel hole, so that a hydrogen circulation passage is formed on the anode bipolar plate. Hydrogen enters the galvanic pile from the hydrogen inlet, and after reacting with oxygen in the air, the hydrogen with excessive reaction flows to the public flow channel hole from the hydrogen flow channel through the bridge hole 1051 and flows out from the public flow channel. When the excessive hydrogen flows out, the vapor water and the liquid water generated during the reaction of the fuel cell stack are carried away.
In this embodiment, the fuel cell stack further includes a pulse exhaust mechanism 20, the pulse exhaust mechanism 20 is disposed in the common flow channel where the hydrogen outlet is located, the pulse exhaust mechanism 20 includes a flow baffle 201, a side wall of the flow baffle 201 is provided with at least one exhaust groove 202, the exhaust groove 202 penetrates through the side wall of the flow baffle 201, and the exhaust groove 202 can move along the extending direction of the common flow channel to switch the bridge opening 1051 between the gas-closed state and the gas-exhausted state; when the flow baffle 201 shields the bridge opening 1051, the corresponding single cell 105 is in a hydrogen gas closed state; when the gas discharge groove 202 communicates with the bridge opening 1051, the corresponding single cell 105 is in a hydrogen gas discharge state.
By arranging the pulse exhaust mechanism 20 in the common flow channel where the hydrogen outlet is located, wherein the flow baffle 201 is used for shielding the bridge hole 1051 at one end of the common flow channel 102 at the hydrogen outlet of the fuel cell, an effect of closing the bridge hole 1051 as the hydrogen outlet of the single cell 105 is generated, so that the corresponding single cell 105 is in a hydrogen gas closed state; the flow baffle 201 is provided with the exhaust groove 202, so that the bridge hole 1051 can be exposed from the exhaust groove 202 and communicated with the common flow channel, and the discharge of the excess hydrogen of the corresponding single battery 105 is realized, so that the corresponding single battery is in an exhaust state. When the exhaust groove 202 moves in the extending direction of the common flow channel 102 and repeatedly passes through the hydrogen outlet side bridge opening 1051 of a certain single cell 105, the pulse-type flow change of the hydrogen of the single cell 105 can be realized, and the generated short-time large flow is beneficial to the discharge of liquid water in the single cell 105 and the requirement of the hydrogen flow channel for water discharge on the hydrogen metering ratio.
Moreover, with the above-mentioned structure, the whole cell stack 10 formed by stacking a plurality of single cells 105 is matched, and the exhaust groove 202 of the exhaust mechanism 20 is operated to sweep the hydrogen outlet bridge opening 1051 of the whole cell stack, so that each single cell 105 can sequentially perform the switching actions of hydrogen gas closing, exhaust and closing along the stacking direction; the exhaust groove 202 is further operated to periodically and repeatedly sweep the entire stack 10 so that each individual cell sequentially performs a hydrogen pulse exhaust action in the stacking direction. From the macroscopic view of the fuel cell stack, the exhaust mechanism can reduce the requirement of hydrogen discharge of the stack on the hydrogen metering ratio on the basis of keeping the hydrogen flow and the pressure of the fuel cell stack relatively stable, thereby reducing the technical difficulty, the cost and the energy consumption of a hydrogen circulating system.
The structure of the flow baffle 201 and the structure and number of the exhaust grooves 202 are not limited, the flow baffle 201 may be a flat plate structure, the elongated exhaust grooves 202 are formed in the flow baffle 201 of the plate structure, and the flow baffle 201 periodically translates along the stacking direction of the fuel cell stack 10, so that the exhaust grooves 202 can sequentially communicate with the bridge holes 1051 of different single cells 105, thereby exhausting the single cells 105. The baffle plate can be driven by a screw motor in a reciprocating manner, or can be in other structural forms, such as a gear rack and the like. Of course, other configurations may be used, as described in the following examples.
The direction in which the single batteries are stacked is the extending direction of the common flow channel, and a plurality of exhaust grooves 202 are arranged on the flow baffle 201 at equal intervals along the extending direction of the common flow channel. The plurality of air discharge grooves 202 are provided at regular intervals on the baffle plate 201 so that the pulse air discharge mechanism 20 performs a pulse air discharge operation of the bridge holes 1051 of the plurality of single cells. By setting the interval of the exhaust grooves 202 appropriately, the frequency of pulse exhaust can be set, thereby being beneficial to achieving the best exhaust and drainage effects.
Of course, the pitch of the exhaust grooves may be set specifically according to the characteristics of the actual cell stack in practical use. For example, if several cells in a certain part of a pile are easy to be flooded, the distance between the exhaust grooves in the part is reduced, so that the part is exhausted in a shorter period, and the accumulated metering ratio of the part is higher than that of other positions, so as to solve the problem that the cells in the part are easy to be flooded.
Example 2
As shown in fig. 1 to 9, the fuel cell stack of the present embodiment has substantially the same structure as that of embodiment 1, except that:
in this embodiment, the baffle plate 201 is a cylindrical structure with two open ends, the exhaust grooves 202 are spirally disposed along the sidewall of the baffle plate 201 at equal intervals, and the baffle plate 201 rotates around its axis. Correspondingly, the shape of the common flow channel where the hydrogen outlet bridge opening 1051 is located in the fuel cell stack corresponds to the outer contour of the flow baffle 201, and enables the flow baffle 201 to rotate relative to the fuel cell stack 10. Similarly, the pitch may also be specifically set according to the actual use situation, and the principle is the same, and is not described herein again. As shown in fig. 8, one end of the projection of the common flow path 102 in the extending direction thereof has a semicircular shape, and the remaining shape is a rectangular shape. The side corresponding to the semicircle is used for accommodating the baffle 201. The baffle plate 201 is formed in a cylindrical structure with both ends open, and hydrogen discharged from the discharge groove 202 can be collected from the inside of the cylinder of the baffle plate 201 and discharged from both ends. The spiral exhaust groove 202 is formed in the side wall of the cylindrical flow baffle 201, when the flow baffle 201 rotates around the axis of the flow baffle 201, the spiral exhaust groove 202 generates a translation effect in the direction along the axis of the flow baffle 201, and each single battery 105 in the extending direction of the hydrogen outlet common flow channel 102 sequentially performs a pulse exhaust action, so that the large-flow exhaust of the corresponding single batteries 105 can be performed in a short time, the discharge of liquid water is promoted, and the requirement for reducing the total hydrogen metering ratio of the stack is further facilitated. Moreover, the number of the single batteries 105 for exhausting and closing the hydrogen in the fuel cell stack is kept constant in the operation process by adopting the structure form of the equidistant spiral, so that the total flow and the total pressure of the hydrogen in the stack are always in a stable state, the total hydrogen flow demand of the stack is reduced, and the technical difficulty, the cost and the energy consumption of a hydrogen supply and hydrogen circulation system are favorably reduced.
Moreover, the number and shape of the corresponding bridge holes 1051 on the bipolar plate of the single cell 105 are not limited as long as the single cell 105 is in a hydrogen gas closed state, the baffle plate can block all the bridge holes of the single cell, and when the spiral exhaust groove 202 corresponds to the single cell 105, all the bridge holes 1051 on the single cell 105 can be communicated with the exhaust groove 202. In this embodiment, four bridge holes 1051 spaced apart from each other are provided in the common flow channel hole corresponding to the hydrogen gas outlet, and the end portions of the bridge holes 1051 have a shape corresponding to the shape of the common flow channel hole. The exhaust slot translation direction 40 and the hydrogen gas flow direction 30 are not limited, and may be the same direction or different directions, and in this embodiment, the latter direction is shown in fig. 2.
The outer wall of the flow baffle 201 is attached to the side surface of the common flow channel corresponding to the flow baffle 201, but no significant friction is generated between the two. That is, the outer diameter of the cylindrical baffle plate 201 is as close as possible to the diameter of the arc corresponding to the common flow channel hole while ensuring the rotation of the cylindrical baffle plate 201. Moreover, the flow baffle 201 is coaxial with the circular arc profile of the common flow channel, the flow baffle 201 is attached to the side surface of the common flow channel to ensure the flow baffle effect, but the flow baffle 201 and the common flow channel are allowed to move or rotate relatively and avoid clamping stagnation, so that the exhaust groove 202 moves relative to the common flow channel. Through the structure, air leakage between the flow baffle plate 201 and the common flow channel is minimized, the pressure in the single battery in the air-closed state can be increased, and the short-time exhaust flow is larger when the air-closed state is switched to the exhaust state, so that drainage is facilitated. Furthermore, the wall thickness of the baffle 201 is as thin as possible while ensuring rigidity to reduce encroachment on the common flow path and avoid significant gas flow resistance.
To ensure the pulse exhaust effect, the width of the exhaust groove 202 is the same as the thickness of the single cell in the fuel cell stack. The pitch of the exhaust grooves 202 is an integral multiple of the groove width of the exhaust grooves 202. The width of the exhaust groove 202 is set to be the same as the thickness of the single battery 105, when the exhaust groove 202 translates across the distance of the thickness of one single battery 105, the bridge opening 1051 of the single battery exhausting at the original large flow rate is blocked by the baffle plate, and the bridge opening 1051 of the adjacent single battery in the translation direction of the exhaust groove 202 is exposed from the exhaust groove 202, so that the exhaust groove 202 is communicated with the hydrogen outlet common flow passage 102. The width of the exhaust groove 202 is set to be the same as the thickness of the single battery 105, so that the adjacent single batteries do not exhaust gas with large flow rate at the same time, and the short-time hydrogen exhaust flow rate of the single battery is improved, thereby being more beneficial to discharging liquid water. The continuous rotation of the baffle plate can make each single cell 105 cycle alternately between the exhaust and the gas closing so as to realize the effect of pulse exhaust inside the cell stack. The screw pitch of the exhaust groove 202 is integral multiple of the groove width of the exhaust groove 202, that is, the screw pitch of the exhaust groove 202 is 2 times, 3 times and 4 times … of the thickness of the single battery 105, so that all the single batteries 105 in the exhaust state are in the same pulse phase, uniform exhaust flow is obtained, and the same exhaust and drainage efficiency is achieved.
Further, the pulse exhaust mechanism 20 further includes a rotating shaft 203, the rotating shaft 203 penetrates through the inner cavity of the flow baffle, is spaced apart from the flow baffle and is fixed to the flow baffle, the rotating shaft 203 is coaxial with the flow baffle, and the rotating shaft 203 rotates around the axis thereof. By fixing the rotating shaft 203 with the baffle plate, when the rotating shaft 203 rotates, the baffle plate rotates along with the rotating shaft 203. The rotating shaft 203 and the baffle plate are arranged at intervals, so that the hydrogen discharged from the gas discharge groove 202 on the baffle plate can flow out from the gap between the rotating shaft 203 and the baffle plate. By adopting the arrangement mode, on one hand, the two ends of the flow baffle are favorably arranged in an open mode, so that the hydrogen is conveniently discharged, on the other hand, the rotating shaft 203 provides rotating power for the flow baffle, the positions of the rotating shaft 203 and the flow baffle are favorably arranged, so that the whole pulse exhaust mechanism 20 is smaller, and the weight and the volume of the fuel cell stack are favorably reduced. In this embodiment, the baffle plate and the rotating shaft 203 are made of a material with acid resistance, oxidation resistance, low wettability and a certain surface smoothness, such as polytetrafluoroethylene.
Specifically, the pulse exhaust mechanism 20 further includes a plurality of connecting rods 205 disposed at intervals, the connecting rods 205 are uniformly distributed on the outer surface of the rotating shaft 203, and two ends of the connecting rods 205 are respectively connected to the outer surface of the rotating shaft 203 and the inner side surface of the baffle plate. The two ends of the connecting rod 205 are respectively connected with the rotating shaft 203 and the baffle plate to realize the relatively fixed connection of the rotating shaft 203 and the baffle plate so as to ensure the coaxial rotation. The plurality of connecting rods 205 are arranged at intervals, so that gaps are formed among the connecting rods 205, and the circulation of hydrogen is facilitated. The plurality of connecting rods 205 are uniformly distributed on the outer surface of the rotating shaft 203, which is beneficial to maintaining the balance of the rotating shaft 203 during rotation, and is further beneficial to improving the stability of the operation of the pulse exhaust mechanism 20.
In this embodiment, the pulse exhaust mechanism 20 further includes a fan 204, and the fan 204 is disposed at an end of the common flow channel and located at a downwind end of the hydrogen flow direction. The end part of the common flow channel corresponding to the hydrogen outlet is provided with the fan blade 204, and the downwind end of the hydrogen flow direction arranged on the fan blade 204 is arranged, when the hydrogen is discharged from the bridge hole 1051 and flows out from the common flow channel, the fan blade 204 is driven to rotate under the action force of the hydrogen airflow, and the pressure difference of the hydrogen at the front end and the rear end of the fan blade 204 is increased due to the rotation of the fan blade 204, so that the discharge of the hydrogen in the fuel cell stack can be accelerated, and the discharge of the hydrogen and the liquid water in the fuel cell stack is more facilitated.
Wherein, the fan blade 204 is connected to one end of the rotating shaft 203. The rotating shaft 203 and the flow baffle are fixed, the fan blade 204 is arranged at the downwind end of the hydrogen flowing direction on the rotating shaft 203, the fan blade 204 is driven to rotate under the action of hydrogen airflow, the fan blade 204 drives the rotating shaft 203 to rotate, so that the flow baffle is driven to rotate, the spiral exhaust groove 202 on the flow baffle is further driven to translate along the axis direction of the rotating shaft 203, and the sequential pulse exhaust action of each single battery in the electric pile is realized. The whole process is that the fan blades 204 are driven to rotate through the discharge of hydrogen, so that power is provided for the operation of the pulse exhaust mechanism 20, a driving motor is not needed to be additionally installed, the cost can be saved, and the structure can be simplified. The rotation speed of the fan 204 is related to the hydrogen flow rate, which is substantially positively correlated to the output current of the fuel cell stack operation, and further, to the water amount of the generated water. When the output current of the fuel cell stack is larger, the hydrogen flow is larger, the rotating speed of the fan blade 204 is faster, so that the rotating speed of the rotating shaft 203 is faster, the exhaust and gas closing frequency of a single cell is higher, namely the pulse frequency is higher, the accumulation time of liquid water is favorably shortened, and the drainage effect is favorably improved.
One end of the flow baffle is provided with a rotating speed sensor, and the rotating speed sensor is used for detecting the rotating speed of the flow baffle. One end of the baffle plate is provided with a rotation speed sensor for detecting whether the baffle plate operates normally, and if the baffle plate stops rotating, the single battery 105 which is shielded and closed is easy to be flooded, so that the fuel cell needs to be stopped suddenly. Of course, the rotation speed sensor is not limited to being connected to the choke plate.
In this embodiment, the shape and size of the through holes of the end plate, the current collecting plate, and the insulating plate, which correspond to the common flow path in which the hydrogen gas outlet is located, are the same as those of the common flow path. By adopting the arrangement mode, when the pulse exhaust mechanism 20 is assembled and disassembled, the galvanic pile does not need to be disassembled, so that the pulse exhaust mechanism 20 is convenient to install or maintain.
Moreover, the fuel cell stack further includes an end cap, the end cap is connected and sealed with the through hole on the end plate through a flange, and two ends of the pulse exhaust mechanism 20 are respectively connected to the end cap or the end plate. The end cover and the end plate are connected and sealed through the flange, so that the whole pulse exhaust mechanism 20 is conveniently arranged in a module in which the end plates are butted, the integration degree is further improved, and meanwhile, the maintenance and the repair are convenient.
In this embodiment, the thickness of the single cell is d, the width of the spiral exhaust groove 202 on the baffle plate in the pulse exhaust mechanism 20 is d, and the pitch is 2 d. The fan blade 204 is installed at the outer end of the rotating shaft 203, the fan blade 204 is driven to rotate by the hydrogen gas flow, and the fan blade 204 is used for driving the rotating shaft 203 to rotate. The maximum radius of the fan blades 204 is smaller than the arc radius of the hydrogen outlet common flow passage. The angle, area and number of the fan blades 204 can be calculated as a fluid, matching a 20rpm rotation speed at maximum hydrogen flow. And a rotating speed sensor is arranged outside the fan blade 204 and used for feeding back the rotating speed so as to prevent the pulse exhaust mechanism 20 from being stuck to cause flooding of a single battery. The outermost end of the rotating shaft 203 is fixed on an end cover provided with a hydrogen outlet port, and the two ends of the shaft are in nested fit with the end plate or the end cover and are allowed to slide. The end cap is flanged and sealed with the end plate. In the rotation period of the pulse exhaust mechanism 20, the ratio of the gas closing time to the gas exhaust time is 2:1, the metering ratio of the hydrogen of the single cell at the exhaust position is 1.9, the metering ratio of the hydrogen of the single cell at the shielding position is about 1.05, and the metering ratio of the hydrogen supply of the comprehensive stack is 1.33.
Example 3
The fuel cell and the pulse exhaust mechanism 20 of the present embodiment are basically the same in structural form as those of embodiment 2, except that:
in this embodiment, the pulse exhaust mechanism 20 further includes a first gear, a second gear and a connecting shaft, the rotating shaft 203 penetrates through an inner cavity of the flow baffle and is fixed to the flow baffle, the rotating shaft 203 is connected to the first gear, the connecting shaft is connected to the second gear, the first gear is engaged with the second gear, the fan blades 204 are connected to an end of the connecting shaft, and the fan blades 204 are located at a downwind end in a hydrogen flow direction. Through being connected pivot 203 and first gear, the connecting axle that is connected with flabellum 204 is connected with the second gear, and it is rotatory to drive flabellum 204 through hydrogen gas flow, thereby flabellum 204 drives the connecting axle rotation and drives the second gear rotation, and first gear and second gear meshing for thereby the second gear drives first gear rotation and drives pivot 203 rotation, finally makes the fender flow board in the pulse exhaust mechanism 20 rotate. The rotating shaft 203 in the pulse exhaust mechanism 20 is driven to rotate through gear transmission, and the rotating speed range of the pulse adjusting mechanism can be adjusted by setting gears with different gear ratios through actual conditions.
The common flow channel where the hydrogen outlet of the fuel cell stack is located is communicated with the hydrogen inlet of the water separator, and the fan blades 204 are arranged at the hydrogen inlet of the water separator. The rotation of flabellum 204 can produce centrifugal effect to liquid water, consequently, sets up flabellum 204 at the hydrogen entrance of water knockout drum, can carry out the primary separation with the liquid water in the hydrogen air current, has vapor-water separation's function, not only is favorable to improving the efficiency of fuel cell stack exhaust and drainage, still is favorable to improving water knockout drum gas-liquid separation's effect.
For example, the exhaust grooves 202 of the cylindrical baffle plate have a width d and a pitch of 3 d. In this embodiment, the power source of the pulse exhaust mechanism 20 is also hydrogen flowing through the common flow passage. The baffle plate and the rotating shaft 203 are arranged on the inner side of the end plate, and the fan blades 204 which are connected with the connecting shaft and are swept by hydrogen are arranged on the outer side of the end plate. After the hydrogen gas passes through the fan blades 204, the fan blades 204 rotate and drive the connecting shaft to rotate, the first gear and the second gear with specific gear ratios are used for driving the flushing and exhausting mechanism 20 to operate, and the rotating speed matched with the maximum hydrogen flow is 30 rpm. The outer side of the end plate is simultaneously provided with a water diversion chamber, the fan blades 204 are positioned in the wind-water chamber, water drops are thrown to the inner wall of the water diversion chamber by utilizing the rotation and centrifugation of the fan blades 204, more water diversion and flow disturbance components can be properly added at the rear end of the water diversion chamber to realize thorough water-vapor separation, the lower end of the water diversion chamber is provided with a water outlet and a discharge valve, and intermittent drainage and waste gas discharge are controlled according to a system. And a hydrogen outlet interface after water-vapor separation is also arranged on the water distribution chamber and is connected with a hydrogen circulation pipeline. The water dividing chamber and the end plate are sealed through a flange. In the rotation period of the pulse exhaust mechanism 20, the ratio of the gas closing time to the gas exhaust time is 3:1, the metering ratio of the hydrogen of the single cell at the exhaust position is 2.05, the metering ratio of the hydrogen of the single cell at the shielding position is about 1.05, and the metering ratio of the hydrogen supply of the comprehensive stack is 1.3.
Example 4
The basic structure of the fuel cell stack in this embodiment is substantially the same as that in embodiment 2, except that:
the power for the rotation of the pulse exhaust mechanism 20 can be derived from the hydrogen gas flowing through the common flow passage itself or by an external power device such as a motor. In this embodiment, the pulse exhaust mechanism 20 further includes a motor, and the rotating shaft 203 is connected to the motor, and the motor drives the rotating shaft 203 to rotate. The motor drives the rotating shaft 203 to rotate, so that the reliable operation of the pulse exhaust mechanism 20 can be ensured, and the smooth pulse exhaust of the fuel cell stack can be further ensured.
The spiral exhaust groove 202 on the cylindrical baffle plate has a groove width of d and a thread pitch of 4 d. The outside of end plate is provided with the template, sets up hydrogen circulation special motor and sealed, explosion-proof construction in the module, and the rotational speed of motor is controllable. The rotating shaft 203 of the pulse exhaust mechanism 20 can be directly connected with a motor, or the pulse exhaust mechanism 20 can be driven by connecting different shafts to regulate the rotating speed of the pulse exhaust mechanism 20, and the rotating speed matched with the maximum hydrogen flow is 60 rpm. In the rotation period of the pulse exhaust mechanism 20, the ratio of the gas closing time to the gas exhaust time is 4:1, the metering ratio of the hydrogen of the single cell at the exhaust position is 2.1, the metering ratio of the hydrogen of the single cell at the shielding position is about 1.05, and the metering ratio of the hydrogen supply of the comprehensive stack is 1.26.
Example 5
This embodiment provides a fuel cell system including the fuel cell stack as provided in any one of embodiments 1 to 4. The fuel cell stack is adopted in the fuel cell system, and the pulse exhaust mechanism 20 in the stack realizes pulse high-flow exhaust of the single cell in the stack, so that the problem of discharging liquid water accumulated in a cell flow passage is solved. Moreover, the sequential exhaust of the single cells in the fuel cell stack is realized by utilizing the structural characteristics of the pulse exhaust mechanism 20, so that the pulse exhaust mechanism has the advantages of keeping the total flow and the total pressure stable, and reducing the requirement of the total hydrogen metering ratio of the fuel cell stack, thereby reducing the technical difficulty, the cost and the energy consumption of a hydrogen circulating system.
With the above embodiments, it can be seen that the present invention achieves the effect of reducing the overall hydrogen metering ratio requirement by introducing the pulse exhaust mechanism 20 inside the fuel cell stack and by sequentially pulsing the exhaust between the individual cells. The invention can be driven by the gas flow per se without additional energy consumption. The invention can also match the low-flow stable drainage requirement of the fuel cell stack by adjusting the spiral parameters and the rotating speed according to the characteristics of different electrode materials, and has high flexibility. The pulse exhaust mechanism 20 has fewer parts, low processing difficulty, less influence on the cost of the fuel cell stack, high integration level, quick assembly and disassembly without disassembling the fuel cell stack, and convenient maintenance. Moreover, the system can be modularly integrated with a water diversion device, an external pulse exhaust mechanism 20 and the like, and the system integration level is improved. The pulse exhaust mechanism 20 of the present invention is more effective for the fuel cell stack 10 having a larger number of cells per unit, and can obtain a more stable hydrogen flow rate and pressure.
While specific embodiments of the invention have been described above, it will be appreciated by those skilled in the art that this is by way of example only, and that the scope of the invention is defined by the appended claims. Various changes and modifications to these embodiments may be made by those skilled in the art without departing from the spirit and scope of the invention, and these changes and modifications are within the scope of the invention.
Claims (12)
1. A fuel cell stack comprises a plurality of bridge holes and a common flow channel, and is characterized by further comprising a pulse exhaust mechanism, wherein the pulse exhaust mechanism is arranged in the common flow channel where a hydrogen outlet is located, the pulse exhaust mechanism comprises a flow baffle plate, the side wall of the flow baffle plate is provided with at least one exhaust groove, the exhaust groove penetrates through the side wall of the flow baffle plate, and the exhaust groove can move along the extending direction of the common flow channel so as to enable a single cell in the stack to be switched between an air-closed state and an exhaust state;
when the flow baffle plate shields the bridge hole, the single battery corresponding to the bridge hole is in a gas-closed state;
when the exhaust groove is communicated with the bridge hole, the single battery corresponding to the bridge hole is in an exhaust state.
2. The fuel cell stack according to claim 1, wherein a plurality of air discharge grooves are provided at intervals on the baffle plate along an extending direction of the common flow channel.
3. The fuel cell stack according to claim 1, wherein the baffle plate is a cylindrical structure with both ends open, the exhaust grooves are spirally formed along a side wall of the baffle plate, and the baffle plate is rotated about an axis thereof.
4. The fuel cell stack of claim 3 wherein the width of the vent slot is the same as the thickness of a single cell in the fuel cell stack;
preferably, the pitch of the air vent groove is not less than an integral multiple of 2 of the thickness of the single battery.
5. The fuel cell stack according to claim 3, wherein the pulse exhaust mechanism further comprises a shaft extending through the inner cavity of the flow baffle, spaced apart from and fixed to the flow baffle, the shaft being coaxial with the flow baffle and the shaft rotating about its axis;
preferably, the pulse exhaust mechanism further comprises a plurality of connecting rods arranged at intervals, the connecting rods are uniformly distributed on the outer surface of the rotating shaft, and two ends of each connecting rod are respectively connected to the outer surface of the rotating shaft and the inner side surface of the flow baffle;
preferably, the pulse exhaust mechanism further comprises a motor, the rotating shaft is connected to the motor, and the motor drives the rotating shaft to rotate.
6. The fuel cell stack of claim 3 wherein the pulse exhaust mechanism further comprises a fan disposed at an end of the common flow path and at a downwind end of the hydrogen flow direction.
7. The fuel cell stack according to claim 6, wherein the pulse exhaust mechanism further comprises a rotating shaft, the rotating shaft passes through an inner cavity of the flow baffle and is fixed with the flow baffle, the fan is connected to one end of the rotating shaft, and the fan is located at a downwind end of the hydrogen flow direction.
8. The fuel cell stack according to claim 6, wherein the pulse exhaust mechanism further comprises a rotating shaft, a first gear, a second gear and a connecting shaft, the rotating shaft passes through the inner cavity of the flow baffle and is fixed with the flow baffle, the rotating shaft is connected with the first gear, the connecting shaft is connected with the second gear, the first gear and the second gear are engaged, the fan blade is connected to an end of the connecting shaft, and the fan blade is located at a downwind end in a hydrogen flow direction.
9. The fuel cell stack according to claim 6, wherein the common flow channel where the hydrogen outlet of the fuel cell stack is located is communicated with the hydrogen inlet of the water separator, and the fan blade is disposed at the hydrogen inlet of the water separator.
10. The fuel cell stack according to claim 3, wherein a rotation speed sensor is provided at one end of the flow baffle plate, the rotation speed sensor detecting a rotation speed of the flow baffle plate.
11. The fuel cell stack according to any one of claims 1-10, wherein the flow baffle abuts a side of the common flow channel edge on which the bridge opening is disposed;
preferably, the fuel cell stack comprises a plurality of single cells, each single cell comprises a bipolar plate, a hydrogen flow channel and a common flow channel hole are arranged on the bipolar plate, and the bridge hole is arranged on the bipolar plate and communicates the hydrogen flow channel with the common flow channel hole;
preferably, the fuel cell stack further comprises an end plate, a collector plate, and an insulating plate, and the shape and size of the through hole on the end plate, the collector plate, and the insulating plate, which correspond to the common flow channel where the hydrogen outlet is located, are consistent with the shape and size of the common flow channel;
preferably, the fuel cell stack further comprises an end cover, the end cover is connected and sealed with the through hole on the end plate through a flange, and two ends of the pulse exhaust mechanism are respectively connected to the end cover or the end plate.
12. A fuel cell system comprising a fuel cell stack according to any one of claims 1 to 11.
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| CN117613308A (en) * | 2024-01-22 | 2024-02-27 | 中国科学院宁波材料技术与工程研究所 | Public channel drainage structure of fuel cell and fuel cell |
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