Air subsystem of fuel cell and fuel cell system

Abstract

The utility model discloses an air subsystem of a fuel cell and a fuel cell system, which are characterized in that a cathode tail gas mixture is used for purging a box body, a branch pipe is obliquely and upwards led in a section of cathode tail gas pipeline between a back pressure valve and a tail gas collecting pipe along the flowing direction of fluid, tail gas and liquid water are separated through gravity, and then deionization and drying treatment are carried out, so that the tail gas and the liquid water are separated. After being neutralized with hydrogen and moisture in the box body, the gas is conveyed to the tail end of the box body, penetrates through a ventilation valve at the tail end of the box body and is discharged into the atmosphere. A tiled design thought and a highly integrated design method are adopted. Parts of parts such as the humidifier and the intercooler are highly integrated, the BOP is integrated in a U shape and is arranged at the bottom of the box body, and flow channel resistance is reduced. A hydrogen concentration sensor is omitted, the design of a purging outlet is simplified, the system reliability and the power generation efficiency are improved, the cost is reduced, and the space utilization rate is increased.

Description

Technical Field

[0001] This utility model belongs to the field of fuel cell equipment technology, and in particular relates to an air subsystem and a fuel cell system. Background Technology

[0002] To meet the IP67 protection rating, fuel cell engines require a sealed enclosure to encapsulate the fuel cell stack. During operation, a small amount of hydrogen and moisture will continuously seep out of the stack. If the hydrogen concentration reaches a certain level, it becomes dangerous. Moisture easily liquefies into water droplets that adhere to the stack, leading to low insulation levels.

[0003] In existing technologies, hydrogen purging methods within the fuel cell enclosure mainly include two approaches:

[0004] One approach involves branching off some of the air from the compressor-supplied fuel cell stack enclosure after the air is cooled by an intercooler. This branch introduces the cooled air into the stack enclosure, blowing away accumulated hydrogen and moisture to the engine's exhaust pipe, thus removing the hydrogen and moisture from the enclosure in real time. However, in existing fuel cell stack enclosure purging schemes, a branch line is used for purging at the stack inlet, consuming a portion of the compressor's power and reducing the fuel cell engine's power generation efficiency. Furthermore, the high oxygen content in the air before entering the stack makes it more susceptible to chemical reactions with the hydrogen inside the enclosure, posing a significant safety hazard.

[0005] Another approach, as disclosed in prior art (CN114068996A), is a fuel cell encapsulation box purging system, including a fuel cell stack, an air compression mechanism, a gas-liquid separation mechanism, and a purging mechanism. The fuel cell stack is housed inside the encapsulation box, and the air compression mechanism delivers atmospheric air into the fuel cell stack. The purging gas introduced into the encapsulation box of the fuel cell stack is the exhaust gas discharged from the fuel cell stack's air outlet, eliminating the need for an additional power consumption from the air compressor and improving the overall efficiency of the fuel cell engine. This approach draws gas from the front end of the back pressure valve, eliminating the need for additional air compressor power. However, this approach alters the working principle of the fuel cell system. The flow resistance of the purging gas is affected by factors such as the power and temperature of the fuel cell system, making it difficult to accurately control the back pressure of the fuel cell system through the back pressure valve. This changes the control strategy of the fuel cell system and also requires consideration of the sealing performance at the rear end of the stack. Since the gas discharged from the cathode contains unreacted ions, directly using it to purge the enclosure may lead to a potential risk of low system insulation. Utility Model Content

[0006] To address the shortcomings of existing technologies, this invention provides an air subsystem for a fuel cell and a fuel cell system.

[0007] The design concept of this invention is to extract exhaust gas between the cathode tailpipe, back pressure valve, and tailpipe manifold, and separate the exhaust gas and liquid water using gravity. The exhaust gas then undergoes ion removal and moisture removal before entering the housing, where it neutralizes with the hydrogen and moisture already present. It is then transported to the vent valve, passes through the vent valve, and is released into the atmosphere. This process fully utilizes the exhaust gas and its inertia for housing purging. All air from the air compressor outlet is delivered to the fuel cell stack, maximizing air supply, saving energy, and improving the fuel cell engine's efficiency. The vent valve design at the rear of the housing eliminates the need for a hydrogen concentration sensor, simplifying the purging outlet layout. This housing purging system simplifies the overall design of the fuel cell engine, reducing space and cost. The entire air subsystem adopts a flat design with a U-shaped airflow channel, resulting in a compact, smooth, aesthetically pleasing, and easy-to-maintain system.

[0008] The specific technical solution of this utility model is as follows:

[0009] An air subsystem for a fuel cell includes a stack housed within an enclosure. The enclosure has a purge inlet and a purge outlet. The stack has an air inlet pipe and a cathode tailpipe pipe. A back pressure valve is provided on the cathode tailpipe pipe, and a tailpipe manifold is provided downstream of the back pressure valve.

[0010] The air subsystem also includes a purge inlet and a purge outlet, as well as a purge pipeline. One end of the purge pipeline is connected to the purge inlet, and the other end is connected to a section of the cathode tail drain pipeline between the back pressure valve and the tail drain manifold. The purge pipeline is equipped with a deionizer and a dryer.

[0011] The gas used for chamber purging comes from the cathode exhaust. The cathode exhaust mixture mainly consists of nitrogen, liquid water, a small amount of hydrogen, and unreacted ions (oxygen ions, hydrogen ions, and electrons), at a temperature of 80℃, with an exhaust pressure ≥25 kPa. The chamber purging requirements are: air pressure 10 kPa, medium air, temperature ≤100℃, and airflow rate 0.5 g / s~2 g / s. This perfectly meets the chamber purging conditions.

[0012] Therefore, utilizing the design concept of the cathode tail gas mixture and its inertia, a branch pipe (i.e., a purge pipe) is obliquely upwards from the cathode tail gas pipe between the back pressure valve and the tail gas manifold, along the fluid flow direction. Due to dynamic inertia, a portion of the mixed gas discharged from the cathode tail gas is drawn through the purge pipe. Because the branch pipe is obliquely upwards, it facilitates the flow of the mixed gas into the branch pipe. Due to gravity, the mixed gas entering the branch pipe undergoes gas-liquid separation. Since the separated tail gas still carries ions that have not fully reacted in the fuel cell stack, subsequent processing requires two steps: ion adsorption (or ion removal) and moisture removal. This necessitates the simultaneous use of a dryer and a deionizer, requiring more space and hindering system integration. Therefore, in this specific embodiment, the deionizer and dryer are integrated together. The tail gas entering the housing neutralizes the water vapor and hydrogen inside the housing and is then transported to the purge outlet at the rear of the housing, from where it is discharged into the atmosphere.

[0013] Furthermore, a humidifier is provided on the air inlet pipeline. The humidifier has a dry-side air inlet, a dry-side air outlet, a wet-side inlet, and a wet-side outlet. The humidifier is connected to the air inlet pipeline through the dry-side air inlet and the dry-side air outlet. At the same time, the humidifier is connected to the cathode tailpipe pipeline through the wet-side inlet and the wet-side outlet. The cathode tailpipe mixed gas humidifies the air entering the stack within the humidifier.

[0014] The humidifier includes a dry side and a wet side. Air flows through the dry side inlet of the humidifier through the dry side channel and then flows out through the dry side outlet. The mixed gas from the cathode exhaust of the fuel cell stack enters the wet side channel of the humidifier through the wet side inlet. The wet side channel and the dry side channel are separated by a membrane tube. Due to the concentration difference of the moisture, the moisture passes through the membrane tube and humidifies the air on the dry side.

[0015] Furthermore, an intercooler is provided upstream of the humidifier on the air intake pipe, and an air compressor is provided upstream of the intercooler.

[0016] In a specific embodiment of this utility model, a bypass branch is further included. One end of the bypass branch is connected to the air pipeline located between the intercooler and the humidifier, and the other end is connected to the tail drain manifold. A bypass valve is provided on the bypass branch.

[0017] The purpose of the bypass valve is: 1. When the hydrogen concentration in the cathode tail is high, the bypass valve is opened to increase the air flow to dilute the hydrogen concentration in the cathode tail; 2. During air pressure surge, the air pressure entering the fuel cell stack is stabilized by opening the bypass valve; 3. When the air pressure entering the fuel cell stack exceeds the specified fuel cell stack inlet pressure, the air pressure entering the fuel cell stack is controlled by the bypass valve.

[0018] In a specific embodiment of this utility model, the intercooler and humidifier are integrated together, which simplifies the system structure, reduces costs, and maintains efficient humidification and intercooling effects, thus helping to improve fuel cell performance.

[0019] In a specific embodiment of this utility model, the air inlet pipeline is equipped with a shut-off valve downstream of the humidifier, and a temperature sensor and a pressure sensor are installed downstream of the shut-off valve. This improves the safety and reliability of the system, helps to detect and solve problems in a timely manner, and ensures the stable operation of the fuel cell.

[0020] In a specific embodiment of this utility model, the cathode tailpipe is further provided with a silencer downstream of the tailpipe manifold, which can reduce noise pollution.

[0021] In a specific embodiment of this utility model, the purge outlet is equipped with a vent valve, which is a waterproof vent valve (protection level IP67), eliminating the need for a hydrogen concentration sensor and simplifying the arrangement of the purge outlet.

[0022] This invention also provides a fuel cell system, including an air subsystem of the fuel cell.

[0023] The beneficial effects of this utility model are:

[0024] (1) The fuel cell air subsystem adopts a surface-mount flow channel design for the stack inlet and outlet. The components of the air subsystem adopt a flat integration scheme. The humidifier, intercooler and all throttle valves are highly integrated, making the entire fuel cell air subsystem compact, smooth and simple. The air flow channel is designed in a U-shape to reduce flow resistance.

[0025] (2) The components of the fuel cell air subsystem are directly fixed to the housing without the need for additional brackets, which greatly simplifies the entire fixing scheme.

[0026] (3) Without changing the working principle of the fuel cell, the mixed gas at the cathode tail and its inertia are used to separate the gas and liquid, adsorb unreacted ions, and remove moisture. The treated tail gas is then purged in the housing without the need for additional air compressor power consumption, thus improving the power generation efficiency of the fuel cell.

[0027] (4) The hydrogen concentration sensor was eliminated, and the mixed gas was discharged into the atmosphere through a waterproof and breathable valve (protection level IP67), which simplified the structural design of the purging outlet and avoided the risk of backflow of the cathode tail discharge. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the air subsystem of the fuel cell of this utility model;

[0029] Figure 2 This is a structural diagram of the air subsystem of the fuel cell of this utility model;

[0030] Figure 3 This is a cross-sectional view of the air subsystem of the fuel cell of this utility model;

[0031] Figure 4 BOP arrangement in the air subsystem of the fuel cell of this utility model. Figure 1 ;

[0032] Figure 5 BOP arrangement in the air subsystem of the fuel cell of this utility model. Figure 2 ;

[0033] Figure 6 BOP arrangement in the air subsystem of the fuel cell of this utility model. Figure 3 ;

[0034] Figure 7 Partial view of the BOP arrangement in the air subsystem of the fuel cell of this utility model. Figure 1 ;

[0035] Figure 8 Partial view of the BOP arrangement in the air subsystem of the fuel cell of this utility model. Figure 2 ;

[0036] Figure 9 Partial view of the BOP arrangement in the air subsystem of the fuel cell of this utility model. Figure 3 ;

[0037] Figure 10 This indicates the flow direction of fluid at the intersection of the cathode tailpipe and the purging pipe in the air subsystem of the fuel cell of this invention.

[0038] The diagram is labeled as follows: 1-fuel cell stack, 11-air inlet line, 111-humidifier, 1111-dry side air inlet, 1112-dry side air outlet, 1113-wet side inlet, 1114-wet side outlet, 112-intercooler, 113-air compressor, 114-stop valve, 115-temperature sensor, 116-pressure sensor, 12-cathode tailpipe line, 121-back pressure valve, 122-tailpipe manifold, 123-silencer, 2-encapsulation box, 21-purge inlet, 22-purge outlet, 3-purge line line, 31-deionizer, 32-dryer, 4-bypass branch, 41-bypass valve. Detailed Implementation

[0039] Depend on Figures 1-9As shown, this utility model provides an air subsystem for a fuel cell, including a stack 1, which is disposed in a package 2. The package 2 has a purge inlet 21 and a purge outlet 22. The stack 1 has an air inlet pipe 11 and a cathode tail drain pipe 12. A back pressure valve 121 is provided on the cathode tail drain pipe 12, and a tail drain manifold 122 is provided downstream of the back pressure valve 121.

[0040] The air subsystem of the fuel cell also includes a purge line 3, one end of which is connected to the purge inlet 21, and the other end is connected to a section of the cathode tail drain line between the back pressure valve 121 and the tail drain manifold 122. The purge line 3 is equipped with a deionizer 31 and a dryer 32.

[0041] Exhaust gas is drawn between the back pressure valve and the tailpipe manifold, and gravity separates the exhaust gas from liquid water. The exhaust gas then passes through a deionizer and dryer to remove ions and moisture, before entering the housing through the purge inlet. There, it neutralizes with the hydrogen and moisture already present in the housing and is then transported to the purge outlet, where it is released into the atmosphere. This process fully utilizes the exhaust gas and its inertia for housing purging. All air from the air compressor outlet is supplied to the fuel cell stack, maximizing air supply, saving energy, and improving the efficiency of the fuel cell engine.

[0042] The purging gas for the packaging box 2 comes from the cathode tailpipe. The cathode tailpipe mixture contains generated water and incompletely reacted ions (oxygen ions, hydrogen ions, and electrons). Therefore, subsequent processing requires two steps: ion adsorption (or ion removal) and moisture removal. This necessitates the simultaneous use of a dryer and a deionizer, requiring more space and hindering system integration. Therefore, in this specific embodiment of the invention, the deionizer 31 and the dryer 32 are integrated together.

[0043] Specifically, a humidifier 111 is provided on the air intake duct 11. The humidifier 111 has a dry-side air inlet 1111, a dry-side air outlet 1112, a wet-side inlet 1113, and a wet-side outlet 1114. The humidifier 111 is connected to the air intake duct 11 through the dry-side air inlet 1111 and the dry-side air outlet 1112. At the same time, the humidifier 111 is connected to the cathode tail exhaust duct 12 through the wet-side inlet 1113 and the wet-side outlet 1114. The cathode tail exhaust mixture humidifies the incoming air in the humidifier 111.

[0044] An intercooler 112 is provided on the air intake pipe 11 upstream of the humidifier 111, and an air compressor 113 is provided upstream of the intercooler 112.

[0045] The fuel cell housing purging system of this utility model also includes a bypass branch 4 as a backup path. One end of the bypass branch 4 is connected to the air pipeline 11 between the intercooler 112 and the humidifier 111, and the other end is connected to the tail drain manifold 122. A bypass valve 41 is also provided on the bypass branch 4.

[0046] To reduce the number of parts, the intercooler 112 and the humidifier 111 are integrated together. Figure 1 The dotted line in the image represents that the intercooler and humidifier are integrated into one unit, which improves integration and saves space.

[0047] The air inlet pipe 11 is equipped with a shut-off valve 114 downstream of the humidifier 111. Downstream of the shut-off valve 114 are a temperature sensor 115 and a pressure sensor 116 for precise control of airflow and status monitoring.

[0048] To reduce noise pollution, a silencer 123 is also installed downstream of the tail drain manifold 122 in the cathode tail drain pipe 12.

[0049] The air subsystem of the fuel cell of this invention eliminates the hydrogen concentration sensor and provides a breather valve at the purge outlet 22, simplifying the arrangement of the purge outlet.

[0050] This invention also provides a fuel cell system, including the air subsystem of the aforementioned fuel cell.

[0051] In use, air exits from the air compressor 113 and enters the intercooler 112. The intercooler 112, humidifier 111, bypass valve 41, back pressure valve 121, and shut-off valve 114 are integrated into one unit. The air from the intercooler 112 outlet splits into two paths: one path enters the humidifier 111's dry-side inlet 1111 (dry-side inlet), passes through the humidifier's dry-side channel, and exits from the humidifier 111's dry-side outlet 1112 (dry-side outlet). This air then passes through the shut-off valve 114 and the humidifier-fuel cell stack inlet pipe into the left distribution plate. The left distribution plate integrates a temperature sensor 115 and a pressure sensor 116. After exiting the left distribution plate, the air enters the fuel cell stack 1. The mixed air exiting the fuel cell stack 1 then enters the right distribution plate and the outlet-humidifier pipe in the fuel cell stack 1 cathode tailpipe. The air enters the wet-side channel of the humidifier 111 through the wet-side inlet 1113. The wet-side channel and the dry-side channel are separated by a membrane tube. Based on the principle of moisture concentration difference, the mixed gas on the wet side humidifies the air on the dry side. Then the mixed gas comes out from the wet-side outlet 1114 of the humidifier 111, passes through the pipe and the back pressure valve 121, and enters the tail drain manifold 122.

[0052] Another path leads to the tail exhaust manifold 122 via bypass valve 41. The mixed gas collected in the tail exhaust manifold 122 is then discharged into the atmosphere via silencer 123.

[0053] When the mixed gas passes through a section of pipe between the back pressure valve 121 and the tail drain manifold 122, due to dynamic inertia along the fluid flow direction, a portion of the mixed gas is drawn through the purge pipe 3. Since the purge pipe 3 is angled upwards, it facilitates the flow of the mixed gas into the purge pipe 3. Due to gravity, the mixed gas entering the purge pipe 3 undergoes gas-liquid separation (e.g., ...). Figure 10 As shown in the diagram, the arrows indicate the flow direction of the fluid. Since the separated exhaust gas still carries ions that were not fully reacted in the fuel cell stack 1, these ions and moisture are removed by the integrated deionizer 31 and dryer 32. The exhaust gas passing through the deionizer 31 and dryer 32 enters the packaging box 2 through the purge inlet 21. Because water vapor and hydrogen may leak from the fuel cell stack 1 inside the packaging box 2, the exhaust gas entering the packaging box 2 neutralizes the water vapor and hydrogen inside the packaging box 2 and is then transported to the purge outlet 22 at the tail of the packaging box 2. The purge outlet 22 is configured as a waterproof vent valve (IP67 protection rating), and the gas is discharged into the atmosphere through the vent valve. Figure 3 The arrows in the diagram indicate the direction of airflow during purging. The flow resistance of the deionizer 31 and dryer 32 is controlled at ≤5kPa@2g / s, and the flow resistance of the entire chamber during purging is controlled at ≤10kPa@2g / s.

[0054] In this invention, all components of the fuel cell air subsystem are laid flat at the bottom and front of the encapsulation box 2, with the airflow channel forming a U-shape. The components of the fuel cell air subsystem are directly fixed to the box body without the need for additional supports, greatly simplifying the entire fixing scheme. The entire integrated scheme is very compact, with smooth fluid flow, and is simple and aesthetically pleasing.

Claims

1. An air subsystem for a fuel cell, comprising a fuel cell stack disposed within an enclosure, the enclosure having a purge inlet and a purge outlet, the fuel cell stack having an air inlet pipe and a cathode tailpipe pipe, characterized in that, A back pressure valve is provided on the cathode tail drain pipeline, and a tail drain manifold is provided downstream of the back pressure valve; The air subsystem also includes a purge line, one end of which is connected to the purge inlet and the other end of which is connected to a section of the cathode tail drain line between the back pressure valve and the tail drain manifold. The purge line is equipped with a deionizer and a dryer.

2. The air subsystem of the fuel cell according to claim 1, characterized in that, The deionizer and dryer are integrated together.

3. The air subsystem of the fuel cell according to claim 1, characterized in that, A humidifier is provided on the air inlet pipeline. The humidifier has a dry-side air inlet, a dry-side air outlet, a wet-side inlet, and a wet-side outlet. The humidifier is connected to the air inlet pipeline through the dry-side air inlet and the dry-side air outlet. At the same time, the humidifier is connected to the cathode tail exhaust pipeline through the wet-side inlet and the wet-side outlet. The cathode tail exhaust humidifies the incoming air in the humidifier.

4. The air subsystem of the fuel cell according to claim 3, characterized in that, An intercooler is located upstream of the humidifier on the air intake pipeline, and an air compressor is located upstream of the intercooler.

5. The air subsystem of the fuel cell according to claim 4, characterized in that, It also includes a bypass branch, one end of which is connected to the air duct located between the intercooler and the humidifier, and the other end is connected to the tail drain manifold; A bypass valve is provided on the bypass branch.

6. The air subsystem of the fuel cell according to claim 4, characterized in that, The intercooler and humidifier are integrated together.

7. The air subsystem of the fuel cell according to claim 3, characterized in that, The air intake pipe is equipped with a shut-off valve downstream of the humidifier, and a temperature sensor and a pressure sensor are located downstream of the shut-off valve.

8. The air subsystem of the fuel cell according to claim 1, characterized in that, The cathode tailpipe is also equipped with a silencer downstream of the tailpipe manifold.

9. The air subsystem of the fuel cell according to claim 1, characterized in that, The purge outlet is equipped with a vent valve.

10. A fuel cell system, characterized in that, The air subsystem of the fuel cell according to any one of claims 1 to 9.

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