A fuel cell dual stack system with secondary water splitting and a vehicle

Abstract

The application relates to the technical field of fuel cells, in particular to a fuel cell double-stack system with secondary water separation and a vehicle, which comprises a hydrogen source, an ejector, a primary water separation device, a secondary water separation device and two electric stacks; the electric stack comprises a hydrogen inlet and a hydrogen outlet; the hydrogen outlets of the two electric stacks are sequentially communicated with the primary water separation device, the ejector, the secondary water separation device and the hydrogen inlets of the two electric stacks; the hydrogen source is communicated with the ejector; by additionally arranging the secondary water separation device in front of the hydrogen inlet, the mixed gas separated by the primary water separation device and a small amount of small-particle-size liquid drops which are not separated can be mixed with fresh hydrogen from the hydrogen source; since the fresh hydrogen is low in temperature, the temperature of the refluxed mixed gas is high, the temperature after the mixture is reduced, the water vapor in the refluxed gas is condensed and separated into liquid water in the secondary water separation device, the water vapor content of the gas entering the stack is reduced, and the performance of the electric stack is prevented from being reduced.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and more specifically to a dual-stack fuel cell system with secondary water separation and a vehicle thereof. Background Technology

[0002] Fuel cells, with their advantages of long driving range, fast refueling, and high load capacity, are increasingly being used in high-power applications such as large vehicles and commercial vehicles. High power output of fuel cell systems can be achieved through a dual-stack approach, which utilizes two fuel cell stacks connected in parallel. To ensure consistent performance between the two stacks, operating parameters such as feed pressure and temperature must be controlled uniformly; therefore, the feed manifold is crucial for flow distribution. However, due to the presence of liquid water in the feed mixture, under gravity, a larger amount of liquid water tends to accumulate in the bottom feed manifold. This water, upon entering the stack, leads to different operating states between the two stacks, resulting in a decrease in the performance of the bottom stack.

[0003] Fuel cell systems often employ hydrogen recirculation in their hydrogen supply path. This involves using a circulating pump or ejector to resupply the fuel cell stack with unused hydrogen from the fuel cell outlet mixture (containing hydrogen, water vapor, nitrogen, liquid water, and others), improving hydrogen utilization. However, due to the significant density difference between liquid water and gas, liquid water entering the stack can potentially block the fuel cell reaction channels, causing the stack to malfunction. Therefore, a gas-liquid separator is typically installed at the hydrogen outlet to separate and discharge liquid water from the gas-liquid mixture, preventing it from recirculating back into the stack. However, smaller droplets cannot be completely separated by the gas-liquid separator. Furthermore, after leaving the separator and entering the downstream piping, water vapor in the mixture may condense due to heat dissipation to the environment and pressure changes. Consequently, a small amount of liquid water remains in the incoming gas, leading to a decrease in stack performance.

[0004] In a single-stall system, liquid water entering the reactor can be separated again through a secondary water separation structure; or the temperature of the water entering the reactor can be increased by hydrogen heat exchange to reduce the precipitation of liquid water. However, for a dual-stall structure fuel cell system, the hydrogen heat exchange scheme is complex to arrange, and secondary water separation schemes are less common. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a secondary water separation scheme for the hydrogen side of a dual-stack fuel cell system, in order to solve the problem of liquid water entering the stack on the hydrogen side, and to provide a secondary water separation system for the dual-stack fuel cell system and vehicle.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] A dual-stack fuel cell system with secondary water separation includes a hydrogen source, an ejector, a primary water separation device, a secondary water separation device, and two fuel cell stacks.

[0008] The fuel cell stack includes a hydrogen inlet and a hydrogen outlet;

[0009] The hydrogen outlets of the two fuel cells are sequentially connected to a primary water separator, an ejector, a secondary water separator, and the hydrogen inlets of the two fuel cells; the secondary water separator has an internal water-dividing space.

[0010] The hydrogen source is connected to the ejector.

[0011] Preferably, the secondary water distribution device includes a main body and a Y-shaped air outlet pipe, and the water distribution space is disposed within the main body;

[0012] The top of the main body is provided with an air inlet that communicates with the water distribution space, and the side wall of the main body is provided with an air outlet. The air outlet is connected to the hydrogen inlets of the two fuel cells through Y-shaped air outlet pipes.

[0013] Preferably, the water separation space includes a gas space and a liquid storage space, the gas space is located above the liquid storage space, and the gas outlet is located on the side wall of the main body opposite to the gas space.

[0014] Preferably, the fuel cell stack includes a coolant outlet;

[0015] The coolant outlet of one or both of the fuel cells exchanges heat with the body sidewall corresponding to the liquid storage space through a heat exchange device.

[0016] Preferably, a drain outlet is provided at the bottom of the main body, the drain outlet is connected to the liquid storage space, and a drain valve is provided on the drain outlet;

[0017] A liquid level sensor is installed in the liquid storage space;

[0018] The drain valve is a solenoid valve, and the drain valve controls the drainage based on feedback from the liquid level sensor.

[0019] Preferably, the liquid level sensor is one of a capacitive liquid level sensor or an ultrasonic liquid level sensor.

[0020] Preferably, the primary water separation device includes a liquid storage chamber;

[0021] The dual-stack fuel cell system also includes a tailpipe valve, which is connected to the liquid storage chamber.

[0022] The drain valve is connected to the liquid storage chamber or to the tail drain valve.

[0023] Preferably, the ejector is connected to the air inlet of the secondary water separator via the hydrogen inlet manifold.

[0024] Preferably, the ejector is replaced by a circulation pump.

[0025] To solve the above-mentioned technical problems, another technical solution adopted by the present invention is as follows:

[0026] A vehicle comprising the aforementioned dual-stack fuel cell system with secondary water separation.

[0027] The beneficial effects of this invention are as follows: By adding a secondary water separator before the hydrogen inlet, the mixed gas separated by the primary water separator and the small amount of small-diameter liquid droplets that were not separated can be mixed with fresh hydrogen from the hydrogen source after entering the circulation pump or ejector. During the mixing process, since the temperature of the fresh hydrogen is low and the temperature of the return mixed gas is high, the temperature decreases after the mixture merges, causing the water vapor in the return gas to condense and precipitate liquid water in the secondary water separator. At the same time, the secondary water separator has a water separation space inside, which allows the mixed gas to expand and condense, further improving the precipitation effect, ensuring that the water vapor content of the gas entering the stack is reduced, and avoiding the degradation of the stack performance. Attached Figure Description

[0028] Figure 1 This is a block diagram of a dual-stack fuel cell system with secondary water separation, according to a specific embodiment of the present invention.

[0029] Figure 2 This is a schematic diagram of the secondary water separation device in Example 1;

[0030] Figure 3 This is a schematic diagram of the secondary water separation device in Example 2;

[0031] Labeling Explanation: 1. Hydrogen source; 2. Pressure reducing valve; 3. Safety valve; 4. Ejector; 5. Hydrogen inlet manifold; 6. Top fuel cell stack; 6a. Top fuel cell stack hydrogen inlet; 6b. Top fuel cell stack hydrogen outlet; 6c. Top fuel cell stack coolant outlet; 6d. Top fuel cell stack coolant inlet; 7. Bottom fuel cell stack; 7a. Bottom fuel cell stack hydrogen inlet; 7b. Bottom fuel cell stack hydrogen outlet; 7c. Bottom fuel cell stack coolant outlet; 7d. Bottom fuel cell stack coolant inlet; 8. Primary water distribution device; 9. Tail drain valve; 10. Secondary water distribution device; 10a. Capacitive level sensor; 10b. High level; 10c. Storage space; 10d. Low level; 10e. Drain outlet; 11. Drain valve; 20a. Ultrasonic level sensor; 20b. High level; 20c. Storage space; 20d. Low level; 20e. Drain outlet; 20f. Ultrasonic level sensor. Detailed Implementation

[0032] To explain in detail the technical content, objectives, and effects of the present invention, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0033] Please refer to Figures 1 to 3A dual-stack fuel cell system with secondary water separation includes a hydrogen source, an ejector, a primary water separation device, a secondary water separation device, and two fuel cell stacks.

[0034] The fuel cell stack includes a hydrogen inlet and a hydrogen outlet;

[0035] The hydrogen outlets of the two fuel cells are sequentially connected to a primary water separator, an ejector, a secondary water separator, and the hydrogen inlets of the two fuel cells; the secondary water separator has an internal water-dividing space.

[0036] The hydrogen source is connected to the ejector.

[0037] As described above, by adding a secondary water separator before the hydrogen inlet, the mixed gas separated by the primary water separator, along with a small amount of small-diameter liquid droplets that were not separated, can be mixed with fresh hydrogen from the hydrogen source after entering the circulating pump or ejector. During the mixing process, because the temperature of the fresh hydrogen is lower and the temperature of the returning mixed gas is higher, the temperature decreases after the mixture merges, causing the water vapor in the returning gas to condense and precipitate liquid water in the secondary water separator. At the same time, the secondary water separator has a water separation space inside, which allows the mixed gas to expand and condense, further improving the precipitation effect, ensuring that the water vapor content of the gas entering the stack is reduced, and avoiding a decline in stack performance.

[0038] Furthermore, the secondary water separation device includes a main body and a Y-shaped air outlet pipe, with the water separation space located within the main body;

[0039] The top of the main body is provided with an air inlet that communicates with the water distribution space, and the side wall of the main body is provided with an air outlet. The air outlet is connected to the hydrogen inlets of the two fuel cells through Y-shaped air outlet pipes.

[0040] Furthermore, the water separation space includes a gas space and a liquid storage space, with the gas space located above the liquid storage space, and the gas outlet located on the side wall of the main body opposite to the gas space.

[0041] Furthermore, the fuel cell stack includes a coolant outlet;

[0042] The coolant outlet of one or both of the fuel cells exchanges heat with the body sidewall corresponding to the liquid storage space through a heat exchange device.

[0043] As can be seen from the above description, the coolant outlet exchanges heat with the side wall of the body corresponding to the liquid storage space through the heat exchange device. Therefore, by using the high temperature coolant at the outlet and designing the manifold, heat conduction and convection heat exchange can be achieved to increase the internal temperature of the secondary water separator, thereby preventing the liquid water in the secondary water separator from freezing.

[0044] Furthermore, a drain outlet is provided at the bottom of the main body, the drain outlet is connected to the liquid storage space, and a drain valve is provided on the drain outlet;

[0045] A liquid level sensor is installed in the liquid storage space;

[0046] The drain valve is a solenoid valve, and the drain valve controls the drainage based on feedback from the liquid level sensor.

[0047] Furthermore, the liquid level sensor is one of a capacitive liquid level sensor or an ultrasonic liquid level sensor.

[0048] Furthermore, the primary water separation device includes a liquid storage chamber;

[0049] The dual-stack fuel cell system also includes a tailpipe valve, which is connected to the liquid storage chamber.

[0050] The drain valve is connected to the liquid storage chamber or to the tail drain valve.

[0051] As can be seen from the above description, by connecting the drain valve to the liquid storage chamber or to the tail drain valve, the length and number of pipelines can be shortened, saving space.

[0052] Furthermore, the ejector is connected to the air inlet of the secondary water separator via the hydrogen inlet manifold.

[0053] Furthermore, the ejector is replaced with a circulation pump.

[0054] Example 1

[0055] Reference Figure 1 and Figure 2 A dual-stack fuel cell system with secondary water separation includes a hydrogen source 1, an ejector 4 (or a circulation pump), a primary water separation device 8, a secondary water separation device 10, and two fuel cell stacks; the two fuel cell stacks are arranged vertically, with the upper fuel cell stack being the top fuel cell stack 6 and the lower fuel cell stack being the bottom fuel cell stack 7.

[0056] The top fuel cell stack 6 includes a top fuel cell stack hydrogen inlet 6a, a top fuel cell stack hydrogen outlet 6b, a top fuel cell stack coolant outlet 6c, and a top fuel cell stack coolant inlet 6d.

[0057] The bottom fuel cell stack 7 includes a bottom fuel cell stack hydrogen inlet 7a, a bottom fuel cell stack hydrogen outlet 7b, a bottom fuel cell stack coolant outlet 7c, and a bottom fuel cell stack coolant inlet 7d;

[0058] The hydrogen outlet 6b of the top fuel cell stack 6 and the hydrogen outlet 7b of the bottom fuel cell stack are respectively connected to the primary water separation device 8, the ejector 4, the secondary water separation device 10, the hydrogen inlet 6a of the top fuel cell stack, and the hydrogen inlet 7a of the bottom fuel cell stack; the secondary water separation device 10 has an internal water separation space.

[0059] The hydrogen source 1 is connected to the ejector 4 in sequence through the pressure reducing valve 2 and the safety valve 3.

[0060] The secondary water separation device 10 includes a main body and a Y-shaped air outlet pipe, and the water separation space is disposed within the main body;

[0061] The top of the main body is provided with an air inlet that communicates with the water distribution space, and the side wall of the main body is provided with an air outlet. The air outlet is connected to the top fuel cell hydrogen inlet 6a and the bottom fuel cell hydrogen inlet 7a through Y-shaped air outlet pipes.

[0062] The water separation space includes a gas space and a liquid storage space 10c. The gas space is located above the liquid storage space 10c, and the gas outlet is located on the side wall of the main body opposite to the gas space.

[0063] The top fuel cell coolant outlet 6c and / or the bottom fuel cell coolant outlet 7c exchange heat with the corresponding body sidewall of the liquid storage space 10c through a heat exchange device.

[0064] The bottom of the main body is provided with a drain outlet 10e, which is connected to the liquid storage space 10c, and a drain valve 11 is provided on the drain outlet 10e.

[0065] A liquid level sensor is installed in the liquid storage space 10c; a high liquid level 10b and a low liquid level 10d are installed in the liquid storage space 10c; wherein, the height of the low liquid level 10d is higher than the height of the drain outlet 10e, which can achieve drainage without venting and avoid gas waste.

[0066] The drain valve 11 is a solenoid valve, and the drain valve 11 controls the drainage according to the feedback of the liquid level sensor (drainage at high liquid level 10b, water shut off at low liquid level 10d).

[0067] The liquid level sensor is a capacitive liquid level sensor 10a.

[0068] The primary water separation device 8 includes a liquid storage chamber;

[0069] The dual-stack fuel cell system also includes a tail valve 9, which is connected to the liquid storage chamber.

[0070] The drain valve 11 is connected to the liquid storage chamber.

[0071] The ejector 4 is connected to the air inlet of the secondary water separator 10 through the hydrogen inlet manifold 5.

[0072] Example 2

[0073] Reference Figure 1 and Figure 3 A dual-stack fuel cell system with secondary water separation, which is similar to Example 1 and will not be described again, wherein...

[0074] The bottom of the main body is provided with a drain outlet 20e, which is connected to the liquid storage space 20c, and a drain valve 11 is provided on the drain outlet 20e.

[0075] The liquid level sensor is an ultrasonic liquid level sensor. The liquid storage space 20c is provided with a high liquid level 20b and a low liquid level 20d. Ultrasonic liquid level sensors 20a and 20f are respectively installed in the high liquid level 20b and the low liquid level 20d. The height of the low liquid level 20d is higher than the height of the drain outlet 20e, which can realize drainage without venting and avoid gas waste.

[0076] Example 3

[0077] A vehicle comprising a dual-stack fuel cell system with secondary water separation as described in Embodiment 1 or Embodiment 2.

[0078] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent modifications made based on the content of the present invention specification and drawings, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A fuel cell dual stack system with secondary water splitting, characterized by, The hydrogen source, the ejector, the primary water distribution device, the secondary water distribution device and the two stacks are included. The stack includes a hydrogen inlet and a hydrogen outlet. The hydrogen outlets of the two stacks are sequentially communicated with the primary water distribution device, the ejector, the secondary water distribution device and the hydrogen inlets of the two stacks respectively. The secondary water distribution device has an internal water distribution space. The hydrogen source is communicated with the ejector. The secondary water distribution device includes a body and a Y-shaped gas outlet pipeline. The top of the body is provided with an air inlet communicated with the water distribution space. The sidewall of the body is provided with a gas outlet communicated with the hydrogen inlets of the two stacks through the Y-shaped gas outlet pipeline. The water distribution space includes a gas space and a liquid storage space. The gas space is above the liquid storage space. The gas outlet is arranged on the sidewall opposite to the gas space. The stack includes a cooling liquid outlet. The cooling liquid outlet of one of the stacks or the two stacks is communicated with the sidewall of the body corresponding to the liquid storage space through a heat exchange device.

2. The fuel cell dual stack system of claim 1, wherein The bottom of the body is provided with a drain outlet communicated with the liquid storage space. The drain outlet is provided with a drain valve. The liquid level sensor is arranged in the liquid storage space.

3. The fuel cell dual stack system of claim 1, wherein The drain valve is an electromagnetic valve.

4. The fuel cell dual stack system of claim 1, wherein The drain valve controls the drainage according to the feedback of the liquid level sensor.

5. A vehicle characterized by comprising: The liquid level sensor is one of a capacitive liquid level sensor and an ultrasonic liquid level sensor. The primary water distribution device includes a liquid storage cavity. The fuel cell double stack system further includes a tail exhaust valve communicated with the liquid storage cavity. The drain valve is communicated with the liquid storage cavity or the tail exhaust valve. The ejector is communicated with the air inlet of the secondary water distribution device through a hydrogen inlet manifold. The ejector is replaced by a circulating pump. The fuel cell double stack system with the secondary water distribution according to any one of claims 1-4.

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