Hydrogen water vapor separation device for fuel cell engine and water drainage method thereof

Abstract

The invention discloses a hydrogen water vapor separation device for a fuel cell engine and a drainage method thereof, comprising a water vapor separator and a stack, the water vapor separator comprising an outer cavity, a middle cavity and an inner cavity, the wall of the middle cavity adopts a heat exchange membrane, the wall of the inner cavity adopts a waterproof breathable membrane, the outer cavity is connected with a cold hydrogen inlet pipe and a hot hydrogen outlet pipe, the cold hydrogen inlet pipe is provided with a hydrogen inlet switch valve and an air intake regulating valve, the inner cavity is connected with a circulation pipe, a hydrogen circulation device is provided on the circulation pipe, the outlets of the hot hydrogen outlet pipe and the circulation pipe are both connected with the hydrogen inlet of the stack, the hydrogen outlet of the stack is connected with the middle cavity through a hydrogen return pipe, a pressure sensor is provided on the hydrogen return pipe, the middle cavity is connected with an exhaust pipe and a drain pipe; a plurality of ceramic balls are provided in the middle cavity. The invention integrates heat exchange and water vapor separation, not only completes the hydrogen intake heating, but also realizes efficient water vapor separation, greatly improves the working performance of the fuel cell, reduces energy consumption and cost, has a simple structure and a small volume.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen fuel cells, and in particular relates to a hydrogen-water vapor separation device for a fuel cell engine and a water drainage method thereof. Background Art

[0002] A fuel cell is a device that converts chemical energy directly into electrical energy. Due to its advantages such as high efficiency, low noise, low starting temperature and zero pollution, it is widely used in fixed power generation, transportation and portable power sources.

[0003] The membrane electrode is the core component of the fuel cell. The membrane electrode is generally composed of a polymer membrane, a catalyst layer and a gas diffusion layer. The main function of the polymer membrane is to conduct protons and isolate the reaction gas. Since the conduction of protons is generally in the form of hydrated protons, the polymer membrane needs to maintain a certain humidity during the operation of the fuel cell, but the humidity cannot be too high. If the humidity is too high, the liquid water formed will cause the membrane electrode to be flooded, hindering the transmission of the reaction gas and causing the performance of the fuel cell to decrease. Therefore, the water management problem of the membrane electrode has an important impact on the performance of the fuel cell.

[0004] The management of water in the cathode of the stack is relatively easy. The humidity can be basically controlled by adjusting the humidification flow and the gas supply metering ratio. However, the management of hydrogen water in the anode of the stack is more difficult. Hydrogen as a fuel works in a closed-loop system. The circulating hydrogen not only needs to separate and discharge the liquid water in the hydrogen-water vapor mixture, but also ensure that the hydrogen is not wasted, and at the same time, the temperature and pressure drop cannot be too obvious. Most of the existing technologies focus on using gas-liquid separators to separate water and gas. There are many ways to achieve this: 1. Using the different specific gravity of gas and liquid during the fluid diversion process, the liquid sinks and separates from the gas. For example, using a baffle structure, the baffle diverts this fluid. For example, in the cyclone water-gas separator structure, the liquid is thrown onto the container wall by the high-speed airflow, and these liquids are separated from the gas after losing kinetic energy; 2. Using waterproof and breathable materials to filter to achieve water-gas separation; 3. Using the different boiling point temperatures to reduce the temperature through the condenser to achieve water-gas separation. However, due to different industries, the requirements for water-gas separation efficiency, media, size, etc. are different. The existing water-gas separation method is not completely applicable to fuel cells. Hydrogen fuel cells have relatively strict requirements for water-gas separation: 1. The water-gas separation efficiency is required to be at least 90%; 2. The volume must be small, especially the vehicle-mounted fuel cell system has high requirements for volume density, and the volume of the water-gas separator cannot be too large; 3. The pressure drop cannot be too large. The hydrogen that passes through the water-gas separator must also participate in the circulation, and the pressure drop will limit the circulation flow; 4. The material must be compatible with hydrogen and heat-resistant and pressure-resistant. At present, there is no ideal hydrogen water-gas separation device that can be used for fuel cell engines. Summary of the invention

[0005] In view of the deficiencies pointed out in the above background technology, the present invention provides a hydrogen water vapor separation device for a fuel cell engine and a water drainage method thereof, aiming to solve the existing problems in the above background technology.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A hydrogen water vapor separation device for a fuel cell engine comprises a water vapor separator and a stack, wherein the water vapor separator comprises an outer cavity, a middle cavity arranged in the outer cavity, and an inner cavity arranged in the middle cavity, forming a three-layer nested structure, wherein the wall of the middle cavity adopts a heat exchange membrane, so that heat exchange can occur between the outer cavity and the middle cavity, and the wall of the inner cavity adopts a waterproof and breathable membrane, so that the gas in the middle cavity can enter the inner cavity, and liquid water is isolated in the middle cavity, so that dry hydrogen is formed in the inner cavity. The outer cavity is connected with a cold hydrogen inlet pipe and a hot hydrogen outlet pipe, and the cold hydrogen inlet pipe is provided with a hydrogen inlet switch valve and an air inlet regulating valve, the inner cavity is connected with a circulation pipe, and a hydrogen circulation device is provided on the circulation pipe, and the outlets of the hot hydrogen outlet pipe and the circulation pipe are both connected with the hydrogen inlet of the stack, and the hydrogen outlet of the stack is connected with the middle cavity through a hydrogen return pipe, and a pressure sensor is provided on the hydrogen return pipe, and the middle cavity is connected with an exhaust pipe and a drain pipe.

[0008] Preferably, a plurality of ceramic balls are arranged in the middle cavity, which disturb the hot and humid gas in the middle cavity, reduce the temperature and make more liquid water precipitate. At the same time, the ceramic balls disturb the airflow, reduce the fluctuation of liquid water, and are more conducive to drainage.

[0009] Preferably, an exhaust valve, a one-way valve and a muffler are sequentially arranged on the exhaust pipe along the gas discharge direction, and the exhaust gas is mixed with the drainage and discharged through the muffler to reduce noise; a drainage valve is arranged on the drainage pipe and the drainage valve is opened when drainage is required.

[0010] Preferably, the water-gas separator is cylindrical to facilitate gas flow; the cold hydrogen inlet pipe and the hot hydrogen outlet pipe are respectively connected to the tops of both sides of the outer cavity, the hydrogen return pipe is connected to the top of the middle cavity, and the circulation pipe is connected to the top of the inner cavity to facilitate gas flow and avoid being affected by liquid water. Furthermore, the exhaust pipe is connected to the top of the middle cavity, the drain pipe is connected to the bottom of the middle cavity, and the water outlet end of the drain pipe is connected to the muffler.

[0011] The present invention further provides a drainage method for a hydrogen water vapor separation device, the steps of which are as follows:

[0012] S1. After the stack is started, the fuel cell generates current and the battery operates normally;

[0013] S2. The fuel cell controller (FCU) calculates the amount of water generated by the stack based on the actual current value of the fuel cell fed back by the current sensor, and determines whether the actual current value meets the current value limit for opening the drain valve. If not, the drain valve is closed; if so, the drain valve is opened;

[0014] S3. After the drain valve is opened, the FCU detects whether the pressure fluctuation in the fuel cell stack is within the normal range. If it is within the normal range, the drain valve is opened periodically according to the parameter group set in the FCU; if it is beyond the normal range, the process proceeds to step S4;

[0015] S4. The FCU determines whether the pressure fluctuation is within the first-level alarm range set in the FCU. If the pressure fluctuation is within the first-level alarm range, the drainage time is reduced and the drainage interval is increased; if the pressure fluctuation exceeds the first-level alarm range, the process proceeds to step S5;

[0016] S5. The FCU determines whether the pressure fluctuation is within the secondary alarm range set in the FCU. If the pressure fluctuation is within the secondary alarm range, the drain valve is closed; if the pressure fluctuation exceeds the secondary alarm range, step S2 is entered to re-determine whether the conditions for opening the drain valve are met, and steps S2 to S5 are repeated.

[0017] Compared with the shortcomings and deficiencies of the prior art, the present invention has the following beneficial effects:

[0018] (1) The present invention effectively separates hydrogen and water vapor at the anode of the stack through heat exchange and the turbulence of ceramic balls. The separated hydrogen passes through a waterproof and breathable membrane to further improve the water vapor separation efficiency. The integrated heat exchange and water vapor separation not only completes the hydrogen intake heating, but also realizes the efficient separation of water vapor, greatly improving the working performance of the fuel cell.

[0019] (2) The hydrogen heat exchanger used in the existing system is eliminated, and the entire device has a compact and simple structure, which reduces manufacturing costs and energy loss.

[0020] (3) The anode exhaust pressure sensor replaces the liquid level meter in the prior art, thereby improving reliability, reducing the number of sensors used in the water-gas separation structure, simplifying the control relationship, and saving costs.

[0021] (4) Integrated exhaust valve can be used for exhaust and drainage.

[0022] (5) Since the hydrogen inlet of the fuel cell stack has already undergone heat exchange, the separation of hydrogen inlet water and gas can be eliminated. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic structural diagram of a hydrogen-water vapor separation device for a fuel cell engine provided by an embodiment of the present invention.

[0024] Figure 2 It is a side structural schematic diagram of a hydrogen-water vapor separation device for a fuel cell engine provided by an embodiment of the present invention.

[0025] Figure 3 It is a schematic diagram of the top view of the structure of a hydrogen-water vapor separation device for a fuel cell engine provided by an embodiment of the present invention.

[0026] Figure 4 It is a schematic diagram of a hydrogen-water vapor separation process for a fuel cell engine provided by an embodiment of the present invention.

[0027] Figure 5 It is a drainage logic diagram of the water-gas separator provided in an embodiment of the present invention.

[0028] In the figure: 1-water-gas separator; 1.1-external cavity; 1.2-middle cavity; 1.3-inner cavity; 1.4-ceramic ball; 2-fuel cell; 3-cold hydrogen inlet pipe; 4-hot hydrogen outlet pipe; 5-circulation pipe; 6-hydrogen circulation device; 7-hydrogen return pipe; 8-pressure sensor; 9-exhaust pipe; 10-exhaust valve; 11-one-way valve; 12-muffler; 13-drain pipe; 14-drain valve; 15-hydrogen inlet switch valve; 16-intake regulating valve. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0030] like Figure 1-3 As shown, a hydrogen water vapor separation device for a fuel cell engine is connected to a water vapor separator 1 on the stack 2 of the fuel cell. The water vapor separator 1 includes an outer cavity 1.1, a middle cavity 1.2 arranged in the outer cavity 1.1, and an inner cavity 1.3 arranged in the middle cavity 1.2. Considering the volume requirements of the fuel cell, the water vapor separator 1 adopts a cylindrical structure, wherein the wall of the middle cavity 1.2 adopts a heat exchange membrane, a plurality of ceramic balls 1.4 are arranged in the middle cavity 1.2, and the wall of the inner cavity 1.3 adopts a waterproof breathable membrane. A cold hydrogen inlet pipe 3 and a hot hydrogen outlet pipe 4 are connected to both sides of the top of the outer cavity 1.1. A hydrogen inlet switch valve 15 and an air inlet regulating valve 16 are arranged on the cold hydrogen inlet pipe 3. The hot hydrogen outlet pipe 4 is connected to the hydrogen inlet of the stack 2. A circulation pipe 5 is connected to the top of the inner cavity 1.3. A hydrogen circulation device 6 is arranged on the circulation pipe 5. The outlet of the circulation pipe 5 is also connected to the hydrogen inlet of the stack 2. The hydrogen outlet of the fuel cell stack 2 is connected to a hydrogen return pipe 7, the outlet of the hydrogen return pipe 7 is connected to the top of the middle cavity 1.2, and a pressure sensor 8 is provided on the hydrogen return pipe 7.

[0031] An exhaust pipe 9 is connected to the top of the middle cavity 1.2, and an exhaust valve 10 and a one-way valve 11 are arranged on the exhaust pipe 9 in sequence along the gas discharge direction; a drain pipe 13 is connected to the bottom of the middle cavity 1.2, and a drain valve 14 is arranged on the drain pipe 13. The gas outlet end of the exhaust pipe 9 and the water outlet end of the drain pipe 13 are both connected to the muffler 12.

[0032] Working principle:

[0033] like Figure 4 As shown, first, the gas source is decompressed at the first level and then supplied with cold hydrogen to the cold hydrogen inlet pipe 3, the hydrogen inlet switch valve 15 is opened, and the gas flow enters the gas inlet regulating valve 16, and the hydrogen inlet regulating valve 16 controls the gas inlet pressure and flow, and then the gas flow enters the outer cavity 1.1 of the water-gas separator 1, and the cold hydrogen in the outer cavity 1.1 and the hot and humid hydrogen in the fuel cell 2 are discharged into the middle cavity 1.2 for heat exchange, so that the temperature of the cold hydrogen in the outer cavity 1.1 is increased, and the hydrogen after heat exchange enters the fuel cell 2 through the hot hydrogen outlet pipe 4 to participate in the reaction and power generation. , the excess hydrogen in the stack 2 is discharged from the stack 2 with the water and part of the heat permeated by the anode and enters the middle cavity 1.2 of the water-gas separator 1. After the humid hot gas enters the middle cavity 1.2, on the one hand, it exchanges heat with the cold hydrogen inlet, the temperature of the humid hot gas is reduced, and the water vapor is condensed and precipitated; on the other hand, the humid hot gas is disturbed by the ceramic balls 1.4 in the middle cavity 1.2, and more liquid water is precipitated by cooling. At the same time, the ceramic balls 1.4 disturb the airflow, reduce the fluctuation of liquid water, and are more conducive to drainage. After that, the gas in the middle cavity 1.2 is further filtered through the waterproof breathable membrane and enters the inner cavity 1.3 to become dry hydrogen. The dry hydrogen in the inner cavity 1.3 passes through the hydrogen reflux device 6 and merges with the hydrogen inlet of the stack 2 and enters the stack 2 again. When the stack 2 needs to be flushed, the exhaust gas passes through the exhaust pipe 9, the exhaust valve 10 and the drain valve 14 are opened, and the exhaust gas and the drainage are mixed and discharged through the muffler 12.

[0034] The present invention integrates heat exchange and water vapor separation, which not only completes the intake heating of hydrogen, but also realizes efficient water vapor separation. Through heat exchange and the turbulence of ceramic balls, the hydrogen and water vapor in the anode of the stack are effectively separated, and the separated hydrogen passes through a waterproof and breathable membrane to further improve the water vapor separation efficiency. In addition, the present invention replaces the liquid level gauge in the water vapor separation structure in the prior art with the anode exhaust pressure sensor 8, which improves reliability, reduces the number of sensors used in the structure, simplifies the control relationship, and saves costs.

[0035] The water-gas separation device provided by the present invention further simplifies the drainage control logic, such as Figure 5 The drainage control method is as follows:

[0036] S1. After the stack is started, the fuel cell generates current;

[0037] S2. The fuel cell controller (FCU) calculates the amount of water generated by the stack based on the actual current value of the fuel cell fed back by the current sensor, and determines whether the actual current value meets the current value limit for opening the drain valve. If not, the drain valve is closed; if so, the drain valve is opened;

[0038] S3. After the drain valve is opened, the FCU detects whether the pressure fluctuation fed back by the pressure sensor is within the normal range. If it is within the normal range, the drain valve is opened periodically according to the parameter group set in the FCU; if it is beyond the normal range, the process proceeds to step S4;

[0039] S4. The FCU determines whether the pressure fluctuation is within the first-level alarm range set in the FCU. If the pressure fluctuation is within the first-level alarm range, the drainage time is reduced and the drainage interval is increased; if the pressure fluctuation exceeds the first-level alarm range, the process proceeds to step S5;

[0040] S5. The FCU determines whether the pressure fluctuation is within the secondary alarm range set in the FCU. If the pressure fluctuation is within the secondary alarm range, the drain valve is closed; if the pressure fluctuation exceeds the secondary alarm range, step S2 is entered to re-determine whether the conditions for opening the drain valve are met, and steps S2 to S5 are repeated.

[0041] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A hydrogen-water vapor separation device for a fuel cell engine, characterized in that: It comprises a water-gas separator and a fuel cell stack, wherein the water-gas separator comprises an outer cavity, a middle cavity arranged in the outer cavity and an inner cavity arranged in the middle cavity, the wall of the middle cavity adopts a heat exchange membrane, the wall of the inner cavity adopts a waterproof and breathable membrane, the outer cavity is connected with a cold hydrogen inlet pipe and a hot hydrogen outlet pipe, the cold hydrogen inlet pipe is provided with a hydrogen inlet switch valve and an air inlet regulating valve, the inner cavity is connected with a circulation pipe, the circulation pipe is provided with a hydrogen circulation device, the outlets of the hot hydrogen outlet pipe and the circulation pipe are both connected with the hydrogen inlet of the fuel cell stack, the hydrogen outlet of the fuel cell stack is connected with the middle cavity through a hydrogen return pipe, the hydrogen return pipe is provided with a pressure sensor, the middle cavity is connected with an exhaust pipe and a drain pipe; a plurality of ceramic balls are arranged in the middle cavity; an exhaust valve, a one-way valve and a muffler are arranged in sequence on the exhaust pipe along the gas discharge direction, and a drain valve is arranged on the drain pipe.

2. The hydrogen-water vapor separation device for a fuel cell engine according to claim 1, characterized in that: The water-gas separator is cylindrical, the cold hydrogen inlet pipe and the hot hydrogen outlet pipe are respectively connected to the tops of both sides of the outer cavity, the hydrogen return pipe is connected to the top of the middle cavity, and the circulation pipe is connected to the top of the inner cavity.

3. The hydrogen-water vapor separation device for a fuel cell engine according to claim 1, characterized in that: The exhaust pipe is connected to the top of the middle cavity, the drain pipe is connected to the bottom of the middle cavity, and the water outlet end of the drain pipe is connected to the muffler.

4. A method for draining water from a hydrogen-water vapor separation device as claimed in any one of claims 1, comprising the following steps: S1. After the stack is started, the fuel cell generates current; S2. The fuel cell controller FCU calculates the amount of water generated by the stack based on the actual current value of the fuel cell fed back by the current sensor, and determines whether the actual current value meets the current value limit for opening the drain valve. If not, the drain valve is closed; if so, the drain valve is opened; S3. After the drain valve is opened, the FCU determines whether the pressure fluctuation in the fuel cell stack fed back by the pressure sensor is within the normal range. If it is within the normal range, the drain valve is opened periodically according to the parameter group set in the FCU; If it is beyond the normal range, go to step S4; S4. The FCU determines whether the pressure fluctuation is within the first-level alarm range set in the FCU. If the pressure fluctuation is within the first-level alarm range, the drainage time is reduced and the drainage interval is increased; if the pressure fluctuation exceeds the first-level alarm range, the process proceeds to step S5; S5. The FCU determines whether the pressure fluctuation is within the secondary alarm range set in the FCU. If the pressure fluctuation is within the secondary alarm range, the drain valve is closed; if the pressure fluctuation exceeds the secondary alarm range, step S2 is entered to re-determine whether the conditions for opening the drain valve are met, and steps S2 to S5 are repeated.

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