Pulse hydrogen supply system for proton exchange membrane fuel cell

A pulse hydrogen supply system for a proton exchange membrane fuel cell is provided. The system comprises a fuel cell, a high-pressure hydrogen bottle, a first pressure relief valve, an ejector, a steam-water separator, a first pressure control valve, a first pressure sensor, a high-pressure vessel, a first electromagnetic valve, a low-pressure vessel, a diaphragm pump, and a second electromagnetic valve. The high-pressure hydrogen bottle, the first pressure relief valve, the first pressure control valve, the ejector and the first pressure sensor are sequentially arranged on a gas inlet pipeline; the high-pressure vessel and the first electromagnetic valve are sequentially arranged on a branch pipeline; the second electromagnetic valve, the low-pressure vessel and the diaphragm pump are sequentially arranged on a first output loop; and the first output pipeline and the gas inlet pipeline form a loop.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of China application no. 202011620870.0, filed on Dec. 31, 2020. The entirety of the above-mentioned patent application is hereby incorporated by reference and made a part of this specification.

BACKGROUND

Technical Field

The present invention belongs to the technical field of fuel cells, and in particular relates to a pulse hydrogen supply system for a proton exchange membrane fuel cell.

Description of Related Art

A membrane electrode assembly of a proton exchange membrane fuel cell (PEMFC) must be kept wet for various monomers of the fuel cell to work effectively. A proton exchange membrane not only can play a role of electrolyte, but also can separate reactants (hydrogen and air). If the membrane is excessively dry in a certain area, an electrochemical reaction may stop. However, if the membrane is excessively wet to cause generation of water drops in a gas flow path, transfer of reactants may be hindered. Therefore, good humidification is necessary for the PEMFC, and redundant water must also be removed from the fuel cell. Water drops on the air side of the fuel cell are easier to remove due to higher gas flow on the air side of the fuel cell.

In the hydrogen supply system of the fuel cell, pulse discharge of hydrogen is mostly achieved through instantaneous boosting and dropping by a proportional valve in the prior art, however, the method is limited by the range of the proportional valve, the generated instantaneous pressure difference is small, and the purging effect on a hydrogen circuit of the fuel cell is poor. Meanwhile, the method may also increase the load on the proportional valve, the service life of the proportional valve is affected, and the control is inconvenient.

SUMMARY

The present invention provides a pulse hydrogen supply system for a proton exchange membrane fuel cell to overcome the problems of small instantaneous pressure difference, poor purging effect, influence on the service life of a proportional valve, difficulty in control and the like in hydrogen pulse discharge through instantaneous boosting and dropping by the proportional valve in the prior art.

A pulse hydrogen supply system for a proton exchange membrane fuel cell provided by the present invention comprises a fuel cell, a high-pressure hydrogen bottle, a first pressure relief valve, an ejector, a steam-water separator, a first pressure control valve, and a first pressure sensor, wherein the ejector is arranged on a gas inlet pipeline communicated between the high-pressure hydrogen bottle and an anode inlet of the fuel cell, the first pressure relief valve is arranged on the gas inlet pipeline adjacent to the high-pressure hydrogen bottle, the steam-water separator is arranged on a first output pipeline at an anode outlet of the fuel cell, the first pressure control valve is arranged at the gas inlet pipeline at a front end of the ejector, and the first pressure sensor is arranged on the gas inlet pipeline adjacent to the anode inlet of the fuel cell. On the basis of the prior art, the present invention is further improved as follows: the system further comprises a high-pressure vessel, a first electromagnetic valve, a low-pressure vessel, a diaphragm pump, and a second electromagnetic valve, wherein the high-pressure vessel is arranged on a branch pipeline of the gas inlet pipeline between the first pressure relief valve and the first pressure control valve, and the first electromagnetic valve is also arranged on the branch pipeline; the second electromagnetic valve, the low-pressure vessel and the diaphragm pump are sequentially arranged on the first output pipeline between the anode outlet of the fuel cell and the steam-water separator, and the first output pipeline and the gas inlet pipeline form a loop.

Preferably, a second pressure relief valve and a second pressure sensor are further arranged on the branch pipeline where the high-pressure vessel is located.

Preferably, the anode outlet of the fuel cell is connected to the ejector through a second output pipeline, and a third electromagnetic valve is arranged on the second output pipeline.

Preferably, the second output pipeline is further provided with a branch pipeline on which a fourth electromagnetic valve is arranged.

Preferably, the ejector is composed of three parts: a receiving chamber, a mixing chamber, and a diffuser; a nozzle is arranged in the receiving chamber, the receiving chamber is provided with a working fluid inlet and an ejector fluid inlet, and the working fluid inlet is connected to the nozzle.

in accordance with the present invention, two pressure wave generators are designed, the pressure of a high-pressure vessel is from a high-pressure hydrogen bottle, and the pressure of a low-pressure vessel is achieved through a diaphragm pump, thus the instantaneous pressure difference of a hydrogen loop can be effectively increased; by quickly opening a first electromagnetic valve and a second electromagnetic valve repeatedly, a diffusion layer between a flow channel and a membrane electrode assembly is dynamically affected by pressure waves, and repeated occurrence of expansion and contraction pressure waves contributes to removing unnecessary liquid from the membrane electrode assembly, thus the purging effect is better, good humidification of a membrane electrode assembly is guaranteed, and it is ensured that no abnormality occurs in the electrochemical reaction of the fuel cell. The pressure of the two pressure wave vessels designed in the present invention is well controlled, and instantaneous propagation of the pressure waves through the opening and closing of the electromagnetic valve is better controlled than instantaneous propagation of the pressure waves through a proportional valve. A branch pipeline of a gas inlet pipeline and a first output pipeline are used as a purging passage, a gas-liquid separator is arranged on the purging passage, and the purging passage is communicated with the gas inlet pipeline, so that hydrogen without water can be still circulated into the fuel cell to avoid the waste of hydrogen; in the purging process, a fourth electromagnetic valve is opened, inert gas (such as accumulated nitrogen) formed in the gas flow channel or a diffusion layer can be removed, which contributes to improving the performance of the fuel cell.

DESCRIPTION OF THE EMBODIMENTS

To make the objectives, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the accompanying drawings and examples. It should be understood that specific embodiments described here are merely used for explaining the present invention and cannot be construed as a limitation to the specific scope of protection of the present invention.

Embodiment

Referring toFIG.1, a pulse hydrogen supply system for a proton exchange membrane fuel cell provided by the embodiment comprises a fuel cell1, a high-pressure hydrogen bottle2, a first pressure relief valve3, an ejector4, a steam-water separator5, a first pressure control valve6, a first pressure sensor7, a high-pressure vessel8, a first electromagnetic valve9, a low-pressure vessel10, a diaphragm pump11, and a second electromagnetic valve12, wherein the ejector4is arranged on a gas inlet pipeline20communicated between the high-pressure hydrogen bottle2and an anode inlet of the fuel cell1, the first pressure relief valve3is arranged on the gas inlet pipeline20adjacent to the high-pressure hydrogen bottle2, the steam-water separator5is arranged on a first output pipeline30at an anode outlet of the fuel cell1, the first pressure control valve6is arranged on the gas inlet pipeline20at a front end of the ejector4, and the first pressure sensor7is arranged on the gas inlet pipeline20adjacent to the anode inlet of the fuel cell1; the high-pressure vessel8is arranged on a branch pipeline21of the gas inlet pipeline20between the first pressure relief valve3and the first pressure control valve6, and the first electromagnetic valve3is also arranged on the branch pipeline21; the second electromagnetic valve12, the low-pressure vessel10and the diaphragm pump11are sequentially arranged on the first output pipeline30between the anode outlet of the fuel cell1and the steam-water separator5, and the first output pipeline30and the gas inlet pipeline20form a loop.

The high-pressure hydrogen bottle2is used for storing and supplying hydrogen, the first pressure relief valve3is used for depressurizing the hydrogen released from the high-pressure hydrogen bottle2, and the pressure can be reduced from 200 bar to 8 bar at the maximum. To guarantee subsequent normal work of the ejector4, an outlet of the first pressure relief valve3must be kept at a relatively high pressure. At a front end of the ejector4, the first pressure control valve6controls the pressure at the anode inlet of the fuel cell1through a pressure signal collected by the first pressure sensor7. Between the first pressure relief valve3and the first pressure control valve6, a portion of the hydrogen is diverted and conveyed into the high-pressure vessel8. On the first output pipeline30, the hydrogen is periodically released into the low-pressure vessel10from the anode outlet of the fuel cell1, the diaphragm pump11is used for creating a low-pressure environment for the low-pressure vessel10, the pressure in the low-pressure container10is generally 20 kPa less than an operating pressure of the fuel cell1, but the operating pressure of the fuel cell1is changed as a working condition changes, and is not fixed. When the hydrogen in the fuel cell1needs to be purged, the first electromagnetic valve9and the second electromagnetic valve12are quickly opened, and generated shock waves pass through the branch pipeline21, the fuel cell1and the first conveying loop30at a high speed, so that any water drops possibly formed in the fuel cell1can be effectively purged into the steam-water separator5to be removed; and the hydrogen without water is still sent back to the gas inlet pipeline20to effectively prevent the problem of local hydrogen shortage in the fuel cell1and avoid the waste of hydrogen.

As a preferred embodiment of the embodiment, a second pressure control valve13and a second pressure sensor14are further arranged on the branch pipeline21where the high-pressure vessel8is located. The second pressure control valve13control the pressure in the high-pressure vessel8by using a pressure signal collected by the second pressure sensor14. The pressure in the high-pressure vessel8is generally 20 kPa higher than the operating pressure of the fuel cell1.

As a preferred embodiment of the embodiment, the anode outlet of the fuel cell1is connected to the ejector4through a second output pipeline40, and a third electromagnetic valve15is arranged on the second output pipeline40. The second output pipeline40serves to recirculate most of gas flow from the anode outlet of the fuel cell1to the ejector4and then to increase the hydrogen pressure to a level at the anode inlet of the fuel cell1to recirculate into the fuel cell1. The third electromagnetic valve15is arranged on the second output pipeline40to prevent pressure waves from being propagated to the second output pipeline40during hydrogen purging. The third electromagnetic valve15remains an open state when hydrogen purging work is not conducted, and the third electromagnetic valve15needs to be closed when the hydrogen purging work is conducted.

As a preferred embodiment of the embodiment, the second output pipeline40is provided with a first branch pipeline41, and a fourth electromagnetic valve16is arranged on the first branch pipeline41. Inert gases necessarily accumulated in the system, such as accumulated nitrogen, can be eliminated through the first branch pipeline41, which is conducive to improving the performance of the fuel cell1.

As a preferred embodiment of the embodiment, referring toFIG.2, the ejector4is composed of three parts: a receiving chamber401, a mixing chamber402, and a diffuser403; a nozzle404is arranged in the receiving chamber401, the receiving chamber401is provided with a working fluid inlet405and an ejector fluid inlet406, and the working fluid inlet405is connected to the nozzle404. The working principle of the ejector4is as follows: when passing through the nozzle404, high-pressure gas in the high-pressure hydrogen bottle2generates a low-pressure area in the receiving chamber401to entrain hydrogen which is not consumed completely from the anode outlet of the fuel cell1, and then the hydrogen is conveyed to the anode inlet of the fuel cell1through the mixing chamber402and the diffuser403. The function thereof is to mix two fluids with different pressures to form a mixed fluid with an intermediate pressure.

In accordance with the embodiment, two pressure wave generators (the high-pressure vessel, the first electromagnetic valve; the low-pressure container, the second electromagnetic valve) are designed, the pressure of the high-pressure vessel is from the high-pressure hydrogen bottle, and the pressure of the low-pressure vessel is achieved through the diaphragm pump, thus the instantaneous pressure difference of a hydrogen loop can be effectively increased; by quickly opening the first electromagnetic valve and the second electromagnetic valve repeatedly, generated shock waves pass through the hydrogen supply pipe and a fuel cell channel at a high speed, thus any water drops possibly formed in the fuel cell can be effectively removed, and extra hydrogen can be provided for the fuel cell to prevent the problem of local hydrogen shortage of the fuel cell.