Fuel cell water circulation system and use method thereof

Abstract

The invention discloses a fuel cell water circulation system and a use method thereof. The fuel cell water circulation system comprises a fuel cell, an ejector and a gas-liquid separator which are circularly communicated in sequence, the fuel cell comprises an electric pile provided with a gas-liquid outlet; introducing gas to purge liquid in the electric pile; the drainage section is communicated with the galvanic pile through the gas-liquid outlet, and a water permeable membrane, a drainage section outlet positioned below the water permeable membrane and an exhaust port positioned above the water permeable membrane are arranged in the drainage section; liquid is discharged from an outlet of the drainage section through the multiple layers of permeable films, and gas is discharged from an exhaust port; the ejector comprises a receiving chamber provided with a gas spraying pipe and a liquid inlet; the liquid inlet is communicated with the outlet of the drainage section; the pressure at the outlet of the gas spray pipe is smaller than that at the drainage section; mixing to form a gas-liquid mixture; the gas-liquid separator is communicated with the ejector and the top of the drainage section and is used for separating a gas-liquid mixture into gas and liquid; when the pressure of the gas-liquid separator is greater than that of the drainage section, liquid flows back to the top of the drainage section to wet the top permeable membrane.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a fuel cell water circulation system and a use method thereof. Background Art

[0002] Hydrogen fuel cells are a clean and efficient power device that has attracted more and more attention. When a hydrogen fuel cell is working, oxygen and hydrogen are introduced into the cathode and anode of the battery respectively, and the reaction generates water, which needs to be discharged from the battery in time to avoid flooding.

[0003] At present, the structure of a fuel cell mainly includes: a stack and a drainage section, wherein the drainage section is used to discharge the generated water. The drainage section is connected to the gas-liquid outlet of the stack. When the fuel cell is working, excess oxygen is introduced into the cathode of the battery, and the excess oxygen purges the generated water in the stack to the gas-liquid outlet of the stack, and the generated water enters the drainage section for discharge.

[0004] The drainage section of a fuel cell is composed of multiple stacked permeable membranes (such as the permeable membrane used in Infinity Power's NFT fuel cell). When the permeable membrane is fully wetted, it can absorb water in the membrane and prevent oxygen from passing through, so that only water is discharged from the drainage section. When the permeable membrane is not fully wetted, the permeable membrane can not only absorb water but also allow oxygen to pass through. In this state, the operation of the battery will be affected. As the fuel cell works, oxygen continuously blows the generated water to the drainage section. The permeable membrane on the surface of the drainage section is constantly in contact with oxygen and may be blown dry by oxygen. At this time, oxygen will enter the drainage section through the permeable membrane on the surface of the drainage section, affecting the operation of the drainage section.

[0005] In the prior art, a water pump is usually used to pump water into the drainage section to humidify the water-permeable membrane on the surface of the drainage section, but this structure will generate additional parasitic power and increase the operating cost of the battery. Summary of the invention

[0006] The purpose of the invention is to solve the technical problem that the top water-permeable membrane of the drainage section of the existing fuel cell is dried, which affects the operation of the battery.

[0007] In order to achieve the above object, the present invention provides a fuel cell water circulation system, comprising a fuel cell, an ejector and a gas-liquid separator which are cyclically connected in sequence; the fuel cell comprises:

[0008] The stack is provided with a stack inlet and a gas-liquid outlet; gas is introduced through the stack inlet to purge liquid generated in the stack, and the liquid is discharged through the gas-liquid outlet;

[0009] A drainage section is connected to the battery stack via the gas-liquid outlet; the drainage section is provided with a multi-layer water-permeable membrane, a drainage section outlet located below the multi-layer water-permeable membrane, and an exhaust port located above the multi-layer water-permeable membrane; the liquid entering the drainage section passes through the multi-layer water-permeable membrane and is discharged from the drainage section outlet, and the gas entering the drainage section is discharged from the exhaust port.

[0010] The ejector includes: a receiving chamber, provided with a gas nozzle and a liquid inlet; the inlet of the gas nozzle is connected to the exhaust port, the outlet of the gas nozzle is arranged close to the liquid inlet, and the liquid inlet is connected to the outlet of the drainage section; the outlet of the gas nozzle sprays gas, so that the pressure at the outlet of the gas nozzle is lower than the pressure in the drainage section, and the liquid discharged from the drainage section is sucked into the ejector; the gas and the liquid are mixed in the ejector to form a gas-liquid mixture.

[0011] The gas-liquid separator is connected to the ejector and the top of the drainage section to separate the gas-liquid mixture discharged from the ejector into gas and liquid; the pressure of the gas-liquid separator is greater than that of the drainage section, so that the liquid flows back to the top of the drainage section to moisten the top water-permeable membrane.

[0012] Optionally, a nozzle is provided at the outlet of the gas nozzle.

[0013] Optionally, the inner diameter of the nozzle gradually decreases from the inlet of the nozzle to the outlet of the nozzle. The nozzle may be in a conical shape.

[0014] Optionally, the ejector further includes a diffusion chamber, which is connected to the receiving chamber and is located downstream of the receiving chamber. The inner diameter of the diffusion chamber gradually increases along the direction from the inlet of the diffusion chamber to the outlet of the diffusion chamber.

[0015] Optionally, the diffusion chamber is trumpet-shaped.

[0016] Optionally, the receiving chamber and the diffusion chamber are integrally formed.

[0017] Optionally, the gas-liquid separator includes a water tank, the upper portion of the water tank is provided with a water tank exhaust port, and the lower portion of the water tank is provided with a water tank drain port.

[0018] Optionally, the gas is oxygen and / or air, and the liquid is water.

[0019] The present invention also provides a method for using the above fuel cell water circulation system, comprising the following steps:

[0020] Step 1, introducing gas from the stack inlet to purge the liquid generated in the stack, and discharging the liquid together through the gas-liquid outlet; the liquid enters the drainage section, passes through the multi-layer water-permeable membrane in the drainage section and is discharged from the drainage section outlet; the gas enters the drainage section and is discharged from the exhaust port above the multi-layer water-permeable membrane.

[0021] Step 2, the gas from the exhaust port is sprayed into the ejector through the outlet of the gas nozzle, so that the pressure at the outlet of the gas nozzle is lower than the pressure in the drainage section, and the liquid discharged from the drainage section is sucked into the ejector; the gas and the liquid are mixed in the ejector to form a gas-liquid mixture and discharged into the gas-liquid separator.

[0022] Step 3, the gas-liquid separator separates the gas-liquid mixture into gas and liquid; after the liquid in the drainage section is sucked into the ejector, the pressure in the drainage section is lower than the pressure in the gas-liquid separator, so that the liquid in the gas-liquid separator flows back to the top of the drainage section to moisten the top water-permeable membrane.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention provides a fuel cell water circulation system, which uses a gas nozzle of an ejector to inject the gas discharged from the battery stack into the ejector at high speed. According to the Bernoulli equation, the pressure is low where the gas flow rate is high, so the gas nozzle ejects gas at high speed so that the pressure at the outlet of the gas nozzle is small, which is lower than the pressure in the drainage section, so that the water discharged from the drainage section is sucked into the ejector according to the pressure difference, so that the pressure in the drainage section is reduced to be lower than the pressure in the gas-liquid separator, so that the water in the gas-liquid separator can flow back to the drainage section. Furthermore, the gas-liquid separator is connected to the top of the drainage section, so that the gas-liquid separator can flow water back to the top of the drainage section to wet the water-permeable membrane on the top layer of the drainage section.

[0025] The present invention returns the water discharged from the drainage section to the drainage section through the pressure difference to wet the water-permeable membrane on the top layer of the drainage section, thereby eliminating the need to set up an additional water pump, generating no additional parasitic power, and reducing the operating cost of the fuel cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the structure of a fuel cell water circulation system according to an embodiment of the present invention.

[0027] Figure 2 Schematic diagram of the structure of an ejector according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0029] like Figure 1 As shown, the present invention provides a fuel cell water circulation system, comprising: a fuel cell, an ejector 500 and a gas-liquid separator 700 that are cyclically connected in sequence. The fuel cell comprises: a stack 100 and a drainage section 200, the stack 100 comprises: a stack inlet 120 and a gas-liquid outlet 110, the stack inlet 120 is used to introduce a reaction gas (oxygen or air), the reaction gas is usually excessive, to purge the liquid (water) generated in the stack 100, and purge the liquid to the gas-liquid outlet 110 for discharge. The gas-liquid outlet 110 is provided at one end of the stack 100 close to the drainage section 200, and is connected to the drainage section 200, and the liquid enters the drainage section 200 after being discharged through the gas-liquid outlet 110.

[0030] The drainage section 200 of the present invention includes: a multi-layer water-permeable membrane 220 (such as the water-permeable membrane used in the NFT fuel cell of Infinity Power) and a drainage section outlet 210. The drainage section outlet 210 is arranged at the bottom of the drainage section 200, and the multi-layer water-permeable membrane 220 is arranged above the drainage section outlet 210. After the liquid is discharged into the drainage section 200 through the gas-liquid outlet 110, it flows through each water-permeable membrane 220 in turn, and then is discharged from the drainage section outlet 210 at the bottom of the drainage section 200.

[0031] The fuel cell of the present invention further includes an exhaust port 300, which is opened on the drainage section 200 and is located above the multi-layer water-permeable membrane 220. After the gas exhausted from the stack 100 enters the drainage section 200 through the gas-liquid outlet 110, the gas can only be exhausted from the exhaust port 300 located above the water-permeable membrane 200 because the water-permeable membrane 220 does not allow the gas to pass through.

[0032] Please combine Figure 1 and Figure 2 The ejector 500 of the present invention includes: a receiving chamber 506, the receiving chamber 506 is provided with a gas nozzle 501 and a liquid inlet 502, the outlet 503 of the gas nozzle 501 is arranged close to the liquid inlet 502, the inlet of the gas nozzle 501 is connected to the exhaust port 300, and the gas discharged from the exhaust port 300 is sprayed into the receiving chamber 506; the liquid inlet 502 is connected to the drainage section outlet 210, and the liquid discharged from the drainage section outlet 210 is introduced into the receiving chamber 506, and the gas and the liquid are mixed in the receiving chamber 506 to form a gas-liquid mixture.

[0033] The present invention utilizes the Bernoulli equation: P+1 / 2ρv 2 +ρgh=C, P is the pressure at the outlet 503 of the gas nozzle, ρ is the gas density, v is the flow rate of the gas at the outlet 503, g is the gravitational acceleration, h is the height difference between the inlet and outlet 503 of the gas nozzle 501, and C is a constant.

[0034] When the gas nozzle 501 is arranged horizontally, ρgh in the equation is zero, C is a constant, and the greater the flow velocity v of the gas at the outlet 503, the smaller the pressure P at the outlet 503 of the gas nozzle. Furthermore, the pressure F at the outlet 503 of the gas nozzle is proportional to the pressure P, and the smaller the pressure P at the outlet 503, the smaller the pressure F at the outlet 503, so that the pressure at the outlet 503 can be lower than the pressure of the drainage section 200, and the liquid discharged from the drainage section 200 is sucked into the receiving chamber 506 by the pressure difference.

[0035] For the case where the gas nozzle 501 is not horizontal, ρgh in the equation changes. At this time, the flow rate v of the gas at the outlet 503 can be further increased to reduce the pressure F at the outlet 503. The specific method is to increase the flow rate of the gas introduced into the inlet 120 of the stack. When the flow rate of the gas introduced into the inlet 120 of the stack increases, the flow rate of the gas discharged from the exhaust port 300 increases, and the flow rate v of the gas at the outlet 503 increases, so that the pressure F at the outlet 503 is further reduced to be less than the pressure of the drainage section 200, and the liquid discharged from the drainage section 200 is sucked into the receiving chamber 506. Therefore, even if the gas nozzle 501 is not horizontally arranged, the liquid discharged from the drainage section 200 can be sucked into the receiving chamber 506 by increasing the flow rate of the gas introduced into the inlet 120 of the stack.

[0036] Please continue reading Figure 1 In this embodiment, the outlet of the ejector 500 of the present invention is arranged at one end of the receiving chamber 506 away from the gas nozzle 501, and is connected to the gas-liquid separator 700, receiving the gas-liquid mixture discharged from the receiving chamber 506, and separating the gas-liquid mixture into gas and liquid. Furthermore, the gas-liquid separator is also connected to the top of the drainage section 200. Since the liquid in the drainage section 200 is sucked into the receiving chamber 506 from the drainage section outlet 210, the pressure in the drainage section 200 is reduced and is lower than the pressure in the gas-liquid separator 700. The liquid in the gas-liquid separator 700 is sucked into the top of the drainage section 200, and the water-permeable membrane 220 at the top layer inside the drainage section 200 is moistened.

[0037] The present invention uses the pressure difference to return the liquid discharged from the drainage section 200 to the drainage section 200, and wets the topmost water-permeable membrane 220 inside the drainage section 200, thereby eliminating the need to set up an additional water pump, generating no additional parasitic power, and reducing the operating cost of the fuel cell.

[0038] In some embodiments, such as Figure 2As shown, a nozzle is provided at the outlet 503 of the gas nozzle, and the inner diameter of the nozzle gradually decreases along the direction from the inlet to the outlet, so as to increase the flow rate of the gas at the outlet 503 of the gas nozzle, so that the liquid in the drainage section 200 is more easily sucked into the receiving chamber 506. According to the continuity equation Q=vA, Q is the gas flow rate entering the gas nozzle 501, v is the flow rate of the gas at the outlet 503 of the gas nozzle, and A is the cross-sectional area of ​​the gas nozzle at the outlet 503. When the gas flow rate Q is constant, the smaller the cross-sectional area A of the outlet 501, the greater the flow rate v of the gas at the outlet 501 of the gas nozzle.

[0039] In some embodiments, the nozzle is conical.

[0040] In some embodiments, the ejector 500 further includes a diffusion chamber 504, which is communicated with the receiving chamber 506 and is located downstream of the receiving chamber 506. The inner diameter of the diffusion chamber 504 gradually increases from the inlet of the diffusion chamber 504 to the outlet of the diffusion chamber 504. In this embodiment, the outlet of the ejector 500 is disposed at one end of the diffusion chamber 504 away from the receiving chamber 506 and is communicated with the gas-liquid separator 700.

[0041] In some embodiments, the diffusion chamber may be trumpet-shaped.

[0042] In some embodiments, the receiving chamber 506 and the diffusion chamber 504 are integrally formed.

[0043] The gas-liquid separator 700 provided by the present invention includes a water tank, the upper part of which is provided with a water tank exhaust port 710, and the lower part of which is provided with a water tank drain port 720. After the gas-liquid mixture discharged from the ejector 500 enters the water tank, the gas is discharged from the water tank exhaust port 710, and the liquid is left in the water tank, thereby achieving the purpose of gas-liquid separation. When the liquid in the water tank is excessive, the liquid can be discharged from the water tank drain port 720.

[0044] The present invention also provides a method for using the above fuel cell water circulation system, comprising the following steps:

[0045] (1) Excess gas is introduced from the stack inlet 120 to purge the liquid generated in the stack, and then purge the liquid to the gas-liquid outlet 110 and into the drainage section 200. The liquid flows through each layer of the water-permeable membrane 220 in turn and is discharged from the drainage section outlet 210; the gas is discharged through the exhaust port 300.

[0046] (2) The gas discharged from the exhaust port 300 enters the ejector 500, and the liquid discharged from the drainage section outlet 210 is sucked into the ejector 500 by the pressure difference. The gas and liquid are mixed in the ejector 500 to form a gas-liquid mixture and discharged into the gas-liquid separator 700.

[0047] (3) The gas-liquid separator 700 separates the gas-liquid mixture into gas and liquid. The gas is discharged from the exhaust port 710 of the water storage tank, and the liquid is sucked into the top of the drainage section 200 through the pressure difference, moistening the topmost water-permeable membrane 220 inside the drainage section 200, thereby avoiding the problem that the gas caused by the drying of the water-permeable membrane 220 enters the drainage section 200 from the water-permeable membrane 220 instead of being discharged from the exhaust port 300, affecting the operation of the drainage section 200.

[0048] The present invention provides a fuel cell water circulation system, which uses pressure difference to return water discharged from a drainage section to the drainage section to moisten the topmost water permeable membrane of the drainage section, thereby eliminating the need to set up an additional water pump, generating no additional parasitic power, and reducing the operating cost of the fuel cell.

[0049] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. A fuel cell water circulation system, characterized in that: It includes a fuel cell, an ejector and a gas-liquid separator which are cyclically connected in sequence; The fuel cell comprises: The stack is provided with a stack inlet and a gas-liquid outlet; gas is introduced through the stack inlet to purge liquid generated in the stack, and the liquid is discharged through the gas-liquid outlet; A drainage section is connected to the battery stack via the gas-liquid outlet; the drainage section is provided with a multi-layer water-permeable membrane, a drainage section outlet located below the multi-layer water-permeable membrane, and an exhaust port located above the multi-layer water-permeable membrane; the liquid entering the drainage section is discharged from the drainage section outlet after passing through the multi-layer water-permeable membrane, and the gas entering the drainage section is discharged from the exhaust port; The ejector comprises: a receiving chamber provided with a gas nozzle and a liquid inlet; the inlet of the gas nozzle is connected to the exhaust port, the outlet of the gas nozzle is arranged close to the liquid inlet, and the liquid inlet is connected to the outlet of the drainage section; the outlet of the gas nozzle ejects gas, so that the pressure at the outlet of the gas nozzle is lower than the pressure in the drainage section, and the liquid discharged from the drainage section is sucked into the ejector; the gas and the liquid are mixed in the ejector to form a gas-liquid mixture; The gas-liquid separator is connected to the ejector and the top of the drainage section to separate the gas-liquid mixture discharged from the ejector into gas and liquid; the pressure of the gas-liquid separator is greater than that of the drainage section, so that the liquid flows back to the top of the drainage section to moisten the top water-permeable membrane.

2. The fuel cell water circulation system according to claim 1, characterized in that: A nozzle is arranged at the outlet of the gas nozzle.

3. The fuel cell water circulation system according to claim 2, characterized in that: The inner diameter of the nozzle gradually decreases along the direction from the inlet of the nozzle to the outlet of the nozzle.

4. The fuel cell water circulation system according to claim 3, characterized in that: The nozzle is in a cone shape.

5. The fuel cell water circulation system according to claim 1, characterized in that: The ejector also includes a diffusion chamber, which is connected to the receiving chamber and is located downstream of the receiving chamber. The inner diameter of the diffusion chamber gradually increases along the direction from the inlet of the diffusion chamber to the outlet of the diffusion chamber.

6. The fuel cell water circulation system according to claim 5, characterized in that: The diffusion chamber is in a trumpet shape.

7. The fuel cell water circulation system according to claim 6, characterized in that: The receiving chamber and the diffusion chamber are integrally formed.

8. The fuel cell water circulation system according to claim 1, characterized in that: The gas-liquid separator comprises a water tank, the upper part of the water tank is provided with a water tank exhaust port, and the lower part of the water tank is provided with a water tank liquid discharge port.

9. The fuel cell water circulation system according to claim 1, characterized in that: The gas is oxygen and / or air, and the liquid is water.

10. A method for using the fuel cell water circulation system according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step 1, introducing gas from the inlet of the battery stack to purge the liquid generated in the battery stack, and discharging the liquid together through the gas-liquid outlet; the liquid enters the drainage section, passes through the multi-layer water-permeable membrane in the drainage section, and is discharged from the drainage section outlet; the gas enters the drainage section, and is discharged from the exhaust port above the multi-layer water-permeable membrane; Step 2, the gas from the exhaust port is sprayed into the ejector through the outlet of the gas nozzle, so that the pressure at the outlet of the gas nozzle is lower than the pressure in the drainage section, and the liquid discharged from the drainage section is sucked into the ejector; the gas and the liquid are mixed in the ejector to form a gas-liquid mixture and discharged into the gas-liquid separator; Step 3, the gas-liquid separator separates the gas-liquid mixture into gas and liquid; after the liquid in the drainage section is sucked into the ejector, the pressure in the drainage section is lower than the pressure in the gas-liquid separator, so that the liquid in the gas-liquid separator flows back to the top of the drainage section to moisten the top water-permeable membrane.

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