Fuel cell water circulation system and method of using same

Abstract

The application 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 sequentially connected in circulation. The fuel cell comprises a stack which is provided with a gas-liquid outlet; a gas is introduced into the stack to blow off liquid in the stack; a drainage section is communicated with the stack through the gas-liquid outlet, and is provided with a water permeable membrane, a drainage section outlet which is located below the water permeable membrane, and an exhaust port which is located above the water permeable membrane; liquid is discharged from the drainage section outlet through the water permeable membrane, and gas is discharged from the exhaust port; the ejector comprises a receiving chamber which is provided with a gas nozzle and a liquid inlet; the gas nozzle inlet is communicated with the exhaust port, and the liquid inlet is communicated with the drainage section outlet; the pressure at the gas nozzle outlet is less than that of the drainage section, so that liquid is sucked into the ejector; and the liquid is mixed with gas to form a gas-liquid mixture; the gas-liquid separator is communicated with the ejector and the top of the drainage section, and separates the gas-liquid mixture into gas and liquid; the pressure of the gas-liquid separator is greater than that of the drainage section, so that liquid flows back to the top of the drainage section to wet the top layer of the water 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 method of using the same. Background Art

[0002] Hydrogen fuel cells are a clean, efficient power device that is attracting increasing attention. When a hydrogen fuel cell is operating, oxygen and hydrogen are introduced into the cathode and anode of the cell, respectively, reacting to produce water. This water needs to be promptly removed from the cell to prevent flooding.

[0003] The current structure of a fuel cell mainly includes a stack and a drainage section, where the drainage section is used to discharge the generated water. The drainage section is connected to the gas-liquid outlet of the stack. During fuel cell operation, excess oxygen is introduced into the cathode of the cell. This excess oxygen purges the generated water in the stack to the gas-liquid outlet of the stack, where it enters the drainage section for discharge.

[0004] The drain section of a fuel cell consists of multiple stacked, permeable membranes (such as those used in Infinity Power's NFT fuel cells). When fully moistened, these membranes absorb water, preventing oxygen from passing through, allowing only water to drain from the drain section. When partially moistened, these membranes not only absorb water but also allow oxygen to pass through, impacting cell operation. As the fuel cell operates, oxygen continuously sweeps generated water into the drain section. The permeable membranes on the drain section's surface come into constant contact with oxygen, potentially drying them out. Oxygen can then enter the drain section through the membranes, impacting its operation.

[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. However, this structure will generate additional parasitic power and increase the operating cost of the battery. Summary of the Invention

[0006] The purpose of the present 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 that are circulated and 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 fuel cell 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 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 conical.

[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 from the inlet 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: introduce gas from the fuel cell stack inlet to purge the liquid generated in the fuel cell stack, and discharge it 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] In 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 that utilizes an ejector's gas nozzle to inject gas exhausted from the fuel cell stack into the ejector at high speed. According to Bernoulli's equation, where gas velocity is high, pressure is low. Therefore, the high-speed gas ejection from the gas nozzle results in a low pressure at the gas nozzle outlet, which is lower than the pressure within the drainage section. Consequently, due to the pressure differential, water exhausted from the drainage section is drawn into the ejector, reducing the pressure within the drainage section to below the pressure within the gas-liquid separator, allowing the water within the gas-liquid separator to flow back into the drainage section. Furthermore, the gas-liquid separator is connected to the top of the drainage section, allowing the gas-liquid separator to return water to the top of the drainage section, moistening the permeable membrane at the top of the drainage section.

[0025] The present invention uses pressure difference to return water discharged from the drainage section to the drainage section to moisten the water-permeable membrane on the top layer of the drainage section, thereby eliminating the need for 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 with reference to 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 circulated and connected in sequence. The fuel cell comprises: a stack 100 and a drainage section 200, and 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), which is usually in excess, 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. The liquid is discharged through the gas-liquid outlet 110 and then enters the drainage section 200.

[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 Infinity Power's NFT fuel cell) 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 sequence, 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 also includes an exhaust port 300, which is provided on the drainage section 200 and located above the multi-layer water-permeable membrane 220. After the gas exhausted from the fuel cell stack 100 enters the drainage section 200 through the gas-liquid outlet 110, it can only be exhausted through 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, where 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 acceleration due to gravity, h is the height difference between the inlet and outlet 503 of the gas nozzle 501, and C is a constant.

[0034] When gas nozzle 501 is positioned horizontally, ρgh in the equation is zero, C is a constant, and the greater the gas flow velocity v at outlet 503, the lower the pressure P at gas nozzle outlet 503. Furthermore, pressure F at gas nozzle outlet 503 is proportional to pressure P. The lower the pressure P at outlet 503, the lower the pressure F at outlet 503. Consequently, the pressure at outlet 503 can be lower than the pressure at drainage section 200, allowing the liquid discharged from drainage section 200 to be drawn into receiving chamber 506 through the pressure differential.

[0035] For the case where the gas nozzle 501 is not horizontal, ρgh in the equation changes. In this case, 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 stack inlet 120. When the flow rate of the gas introduced into the stack inlet 120 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, thereby further reducing the pressure F at the outlet 503 and making it less than the pressure of the drainage section 200. 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 stack inlet 120.

[0036] Please continue reading Figure 1 In this embodiment, the outlet of the ejector 500 of the present invention is located at the 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. As the liquid in the drainage section 200 is drawn into the receiving chamber 506 through the drainage section outlet 210, the pressure in the drainage section 200 decreases and becomes lower than the pressure within the gas-liquid separator 700. The liquid in the gas-liquid separator 700 is then drawn into the top of the drainage section 200, moistening the topmost permeable membrane 220 within the drainage section 200.

[0037] The present invention uses the pressure difference to return the liquid discharged from the drainage section 200 to the drainage section 200, and moistens the top-layer water-permeable membrane 220 inside the drainage section 200, thereby eliminating the need for 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. The nozzle's inner diameter gradually decreases from its inlet to its outlet, increasing the gas flow rate at the outlet 503 and allowing the liquid in the drainage section 200 to be more easily drawn into the receiving chamber 506. According to the continuity equation Q = vA, where Q is the gas flow rate entering the gas nozzle 501, v is the gas flow rate at the outlet 503, and A is the cross-sectional area of ​​the gas nozzle at the outlet 503, for a constant gas flow rate Q, the smaller the cross-sectional area A of the outlet 501, the greater the gas flow rate v at the outlet 501.

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

[0040] In some embodiments, the ejector 500 further includes a diffuser chamber 504, which is connected to the receiving chamber 506 and is located downstream of the receiving chamber 506. The inner diameter of the diffuser chamber 504 gradually increases from the inlet to the outlet of the diffuser chamber 504. In this embodiment, the outlet of the ejector 500 is located at the end of the diffuser chamber 504 away from the receiving chamber 506 and is connected to 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 reservoir, with a water reservoir vent 710 located at its upper portion and a water reservoir drain 720 located at its lower portion. After the gas-liquid mixture discharged from the ejector 500 enters the water reservoir, the gas is discharged through the water reservoir vent 710, while the liquid remains within the reservoir, thereby achieving gas-liquid separation. If the liquid in the water reservoir becomes excessive, the liquid can be discharged through the water reservoir drain 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 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 water tank exhaust port 710, and the liquid is sucked into the top of the drainage section 200 through the pressure difference, moistening the topmost permeable membrane 220 inside the drainage section 200, thereby avoiding the problem that the gas caused by the drying of the permeable membrane 220 enters the drainage section 200 from the 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 the drainage section to the drainage section to moisten the top-layer water-permeable membrane of the drainage section. This eliminates the need for an additional water pump, does not generate additional parasitic power, and reduces the operating cost of the fuel cell.

[0049] Although the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description is not intended to limit the present invention. After reading the above description, various modifications and substitutions of the present invention will become apparent to those skilled in the art. Therefore, the scope of protection of the present invention should be defined 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 circulated and 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, connected to the fuel cell 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; liquid entering the drainage section passes through the multi-layer water-permeable membrane and is discharged from the drainage section outlet, and 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 near 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, thereby sucking the liquid discharged from the drainage section 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 permeable membrane.

2. The fuel cell water circulation system according to claim 1, wherein: A nozzle is provided at the outlet of the gas nozzle.

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

4. The fuel cell water circulation system according to claim 3, wherein: The nozzle is conical.

5. The fuel cell water circulation system according to claim 1, wherein: 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 from the inlet 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 trumpet-shaped.

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

8. The fuel cell water circulation system according to claim 1, wherein: The gas-liquid separator comprises a water tank, wherein 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 liquid discharge port.

9. The fuel cell water circulation system according to claim 1, wherein: 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 stack inlet to purge the liquid generated in the stack, and discharging the liquid 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 injected 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, which is then discharged into the gas-liquid separator; In 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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