Energy-saving gas supply system for fuel cell test bench

Abstract

The application belongs to the field of fuel cell testing, and discloses an energy-saving gas supply system of a fuel cell testing platform, which comprises a main path, wherein the main path comprises, in sequence, an air filter, an air compressor, a cooler, a main path valve, a flow meter and a humidifier; the humidifier is connected with a cathode inlet of an electric pile; an electric pile outlet is connected with a back pressure valve; a branch path is further arranged in the testing platform; an inlet connecting end of the branch path is arranged between the cooler and the main path valve; an outlet connecting end of the branch path is arranged between the electric pile and the back pressure valve; and a branch path adjusting valve is arranged on the branch path. The system has a simple structure, can significantly reduce energy consumption, save cost and improve production efficiency.

Description

Technical Field

[0001] This invention belongs to the field of fuel cell testing. Specifically, it relates to an energy-saving gas supply system for a fuel cell test bench, specifically an energy-saving gas supply system built into or adjacent to the test bench. More specifically, it relates to a cathode air supply system for a proton exchange membrane fuel cell testing and activation bench. Background Technology

[0002] Research and production of fuel cells require testing. The equipment used for testing is generally called a test bench. A test bench consists of several subsystems, including the anode fuel hydrogen supply for the fuel cell stack, the stack cooling system, the cathode oxidant air supply, the electronic load for consuming the generated electricity, and a control system such as a PLC system. Among these, the cathode air supply is the main energy-consuming subsystem, and its energy consumption needs to be significantly reduced.

[0003] Fuel cell testing, especially pressurized proton exchange membrane fuel cell testing, requires the use of an air compressor to provide pressurized cathode air to the stack as the oxidant for the reaction. The operating pressure generally increases with power output. This is because as power output increases, current density increases accordingly, leading to a faster rate of oxygen consumption. Therefore, pressurization is necessary to increase the oxygen concentration and reduce the adverse effects of concentration diffusion on oxygen transfer.

[0004] In fuel cell engine systems used in applications, the air compressor's speed changes according to the output of the fuel cell stack. High output corresponds to high speed, high pressure, and high gas volume, while low output corresponds to low speed, low pressure, and low gas volume. On the other hand, the resistance encountered by the gas in the flow field increases rapidly with the increase of gas flow rate, which is another major reason why high flow rate requires high pressure.

[0005] For air supply, especially for high-power testing, a remote air supply system outside the test bench is typically used. This system includes compressors and storage tanks, which, through pipelines and valves, overcome resistance to deliver air to the test bench. Air compressors provide a high-pressure air source, typically at 0.7 MPa. This pressure is then reduced on the test bench, reaching the fuel cell at 0.02–0.20 MPa, with a small percentage possibly at 0.30 MPa. A significant proportion of compression work is wasted, and the air supply system requires considerable space and is costly. Particularly in high-power testing, using a remote, conventional compressor and storage supply method results in significantly higher space requirements, costs, and energy consumption compared to a low-pressure air supply system integrated into or near the test bench.

[0006] The operation of fuel cell stacks is characterized by low-pressure, low-flow air for low power and high-pressure, high-flow air for high power. Therefore, if the overall technology is not studied, the air compressors used directly on test benches with built-in or nearby air compressors are prone to surge in a certain flow range, which is characteristic of air compressors. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings in the above-mentioned background technology and provide a cathode air supply subsystem for a fuel cell test bench, or simply an energy-saving air supply system for a fuel cell test bench. This system has a simple structure and can significantly reduce energy consumption, save costs, and improve production efficiency.

[0008] The technical solution adopted by this invention to solve its technical problem is: an energy-saving gas supply system for a fuel cell test bench, including a main line, which includes an air filter, an air compressor, a cooler, a main line valve, a flow meter, and a humidifier connected in sequence; the end of the humidifier is connected to the cathode inlet of the fuel cell stack, and the outlet of the fuel cell stack is connected to the back pressure valve; the system also has a branch line, the inlet of which is located between the cooler and the main line valve, and the outlet of which is located between the fuel cell stack and the back pressure valve; the branch line is equipped with a branch line regulating valve.

[0009] Furthermore, the air compressor is a low-pressure air compressor; the air compressor is installed inside the test bench or adjacent to the outside of the test bench.

[0010] Furthermore, when the air compressor is installed inside the test bench, the air compressor is 1 to 5 meters away from the test bench;

[0011] Furthermore, when the air compressor is installed inside the test bench, the main circuit and branch circuit are installed inside the test bench; when the air compressor is installed outside the test bench, the main circuit in which the air filter, air compressor, and cooler are sequentially connected is installed outside the test bench.

[0012] When the air compressor is located outside the test bench, the back pressure valve is connected to an exhaust pipe via a pipeline, and the exhaust pipe and its pipeline are located outside the test bench; the air filter is also connected to a fresh air pipe, and the cooler is connected to the main valve via an air supply pipe.

[0013] Furthermore, the fuel cell stack is disposed outside the test bench;

[0014] Furthermore, a gas detector is also provided between the humidifier and the fuel cell stack to detect air temperature, pressure, and humidity.

[0015] Furthermore, the opening degree of the branch regulating valve is adjustable.

[0016] The section of the line connecting the fuel cell stack outlet to the back pressure valve is the exhaust gas emission section.

[0017] The energy-saving air supply system of the test bench includes a PLC system, which is connected to an air compressor, an air source valve, an air supply valve, a gas detector, a main valve, a flow meter, a humidifier, a branch regulating valve, and a back pressure valve.

[0018] The maximum pressure of the low-pressure air compressor at its rated flow rate is 0.1 to 0.3 MPa higher than the fuel cell stack operating pressure (0.02 to 0.20 MPa), which is taken as 0.4 to 0.50 MPa. For comparison, the maximum pressure of the air compressor at its rated flow rate used in conventional technology is generally 0.60 to 0.70 MPa. Therefore, this system is more energy-efficient than conventional technology. At the same time, the pressure variation range is reduced, and therefore the gas pressure point at which the surge flow occurs in this system is also relatively lower.

[0019] Based on the surge characteristics and speed regulation lag characteristics of the air compressor, this system maintains the air compressor speed and opens the branch regulating valve when surge occurs near low flow. Part of the gas flow is diverted from the branch to the fuel cell stack exhaust gas discharge line section. The fuel cell stack flow is detected by the main flow meter and used as the basis for controlling the opening of the branch regulating valve. This not only speeds up the flow regulation speed of the test system and prevents surge, but also reduces the fuel cell stack flow to the required value.

[0020] The gas detector includes the ability to detect temperature, pressure, and humidity, as well as the parameters of the air at the fuel cell inlet. The gas detector is connected to a PLC system and transmits the detected air temperature, humidity, pressure, and flow rate signals to the PLC system. The PLC system uses the signals as the basis for regulation and adjusts the temperature, humidity, pressure, and flow rate.

[0021] For a specific fuel cell stack, flow meters, branch regulating valves, and back pressure valves are used for control.

[0022] For specific flow rates, when the flow rate exceeds 150% of the surge zone flow rate, and the fuel cell stack flow rate needs to be adjusted, the air compressor speed should be operated according to the characteristic curve based on the air compressor's operating curve.

[0023] When the flow rate is below 150% of the surge zone flow rate, and the air compressor speed remains unchanged, first adjust the opening of the branch regulating valve to make the flow meter data the system operating set data, then adjust the back pressure valve to adjust the operating pressure to the set pressure, and then adjust the branch regulating valve. The two should not be adjusted at the same time.

[0024] The beneficial effects of this invention compared to the prior art are:

[0025] 1) The system test conditions are closer to the real operating conditions, which can better reflect the performance of the fuel cell stack in actual operation and is conducive to optimizing the fuel cell stack operating conditions through testing;

[0026] 2) It will have energy-saving effects in terms of electricity, especially for high-power testing or activation applications;

[0027] 3) Reducing the bulky external air supply system of the test bench lowers the complexity of the equipment system and facilitates flexible layout;

[0028] 4) It facilitates the development of fast-response air supply systems and enables dynamic testing;

[0029] This invention provides an energy-saving air supply system for a fuel cell test bench, providing air supply for the test bench and exhibiting good flow range adaptability. When the stack flow rate needs adjustment, the air compressor speed operates according to the optimal characteristic curve based on the air compressor's operating curve. When the flow rate is slightly higher than the surge zone flow rate or lower, the air compressor speed remains unchanged. First, the opening of the branch regulating valve is adjusted to make the flow meter data match the system operating setpoint. Then, the back pressure valve is adjusted to adjust the operating pressure to the set pressure. The regulating valve and back pressure valve are then adjusted sequentially. The advantages of the system provided by this invention are that the test conditions are closer to real operating conditions, better reflecting the actual performance of the fuel cell stack and facilitating the optimization of fuel cell stack operating conditions; it produces energy-saving effects in terms of electricity, especially for high-power testing or activation applications; it reduces the need for a large external air supply system for the test bench, lowers the complexity of the equipment system, and facilitates equipment layout; and it is beneficial for developing a fast-response air supply system and realizing dynamic testing. Attached Figure Description

[0030] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0031] Figure 1 This is a schematic diagram of the existing air supply system structure.

[0032] Figure 2 This is a schematic diagram of the energy-saving gas supply system built into the test bench in Embodiment 1 of the present invention.

[0033] Figure 3 This is a schematic diagram of the split-type energy-saving gas supply system of the test bench in Embodiment 2 of the present invention.

[0034] In the diagram: 1. Existing air supply system; 2. Cathode air control system; 3. Fuel cell stack; 4. Air supply system; 11. Existing air filter; 12. High-pressure air compressor; 13. Existing cooler; 14. Air tank; 21. Air source valve; 22. Pressure reducing valve; 23. Air supply valve; 24. Flow controller; 25. Existing humidifier; 26. Existing gas detector; 27. Existing back pressure valve; 41. Air filter; 42. Air compressor; 43. Cooler; 44. Main valve; 45. Flow meter; 46. Humidifier; 47. Gas detector; 48. Branch regulating valve; 49. Back pressure valve; 431. Air supply pipe; 432. Indoor / outdoor partition; 433. Fresh air pipe; 434. Exhaust pipe. Detailed Implementation

[0035] The present invention will be further described below with reference to the accompanying drawings, but the present invention is not limited to the following embodiments.

[0036] In this embodiment, the air compressor, air source valve, air supply valve, humidifier gas detector, main valve, flow meter, branch regulating valve, and back pressure valve connected to the PLC system are not limited to a specific model. The air source valve, air supply valve, main valve, branch regulating valve, and back pressure valve can all be valves capable of receiving control signals from the PLC system to achieve opening and closing functions. The flow meter model is not limited, as long as it can measure flow and feed the signal back to the PLC system. The gas detector model is not limited, as long as it can measure temperature, humidity, pressure, and flow and feed the signal back to the PLC system. To simplify and highlight the description of this technology, the hydrogen system, cooling system, and control system are not shown, but this does not affect the essence of the technical content.

[0037] Example 1

[0038] An energy-saving gas supply system for a test bench, such as Figure 2 As shown, the system includes a main circuit, which comprises an air filter 41, an air compressor 42, a cooler 43, a main circuit valve 44, a flow meter 45, and a humidifier 46 connected in sequence. The end of the humidifier 46 is connected to the cathode inlet of the fuel cell stack 3, and the outlet of the fuel cell stack 3 is connected to the back pressure valve 49. The system also includes a branch circuit, with the branch circuit inlet connected between the cooler 43 and the main circuit valve 44, and the branch circuit outlet connected between the fuel cell stack 3 and the back pressure valve 49. A branch circuit regulating valve 48 is provided on the branch circuit.

[0039] The air compressor 42 is a low-pressure air compressor;

[0040] The fuel cell stack 3 is located outside the test bench;

[0041] A gas detector 47 is also provided between the humidifier 46 and the fuel cell stack 3; used to detect air temperature, pressure and humidity.

[0042] The opening degree of the branch regulating valve 48 is adjustable.

[0043] The energy-saving air supply system of the test bench includes a PLC system, which is connected to an air compressor 42, an air source valve, an air supply valve, a gas detector 47, a main valve 44, a flow meter 45, a humidifier 46, a branch regulating valve 48, and a back pressure valve 49.

[0044] The test bench uses a low-pressure air compressor 42, whose rated flow rate and maximum pressure are 0.10~0.30 MPa higher than the maximum operating pressure of the fuel cell stack, preferably 0.40~0.50 MPa. The heat generated by its compression is also less than that generated by the comparative high-pressure air compressor 12. Therefore, the cooling load required by the cooler 43 is smaller than that of the existing cooler 13.

[0045] In certain operating conditions, such as when the main and branch air supply is simultaneously and quickly cut off, the air compressor 42 may not have stopped running due to inertia, resulting in relatively large vibrations and noise. Therefore, the branch line is connected between the cooler 43 and the main valve 44, instead of between the main valve 44 and the flow meter 45.

[0046] The maximum pressure of the low-pressure air compressor 42 at rated flow is lower than that of air compressors using conventional technology. Therefore, the pressure value at the point where surge flow occurs is relatively lower, and the range of directly controllable stable flow increases.

[0047] Based on the surge characteristic flow value of the specific low-pressure air compressor 42, when the surge is close to occurring, take 150% of the surge point flow rate, maintain the speed of the low-pressure air compressor 42, open the branch regulating valve 48, and part of the gas flow is diverted from the branch to the back pressure valve 49 on the fuel cell stack exhaust gas discharge line section. The flow rate of fuel cell stack 3 is detected by the main flow meter 45, which is the basis for controlling the opening of the branch regulating valve 48, so that the flow rate of fuel cell stack 3 is reduced to the required value.

[0048] For a specific fuel cell stack 3, the optimal operating characteristic curves of different air compressors 42 are different. The test bench system selectively simulates the flow and pressure relationship of the fuel cell stack 3 according to the characteristic curves of different air compressors 42, and specifically uses flow meter 45, branch regulating valve 48, and back pressure valve 49 for regulation.

[0049] For specific flow rates, when the flow rate exceeds 150% of the surge zone flow rate, the flow rate of fuel cell stack 3 needs to be adjusted. According to the working curve of air compressor 42, the speed of air compressor 42 operates according to the optimal characteristic curve.

[0050] When the flow rate is below 150% of the surge zone flow rate, the speed of the low-pressure air compressor 42 remains unchanged. First, adjust the opening of the branch regulating valve 48 so that the flow meter 45 data is the system operating set data. Then, adjust the back pressure valve 49 to adjust the operating pressure to the set pressure. Then, adjust the branch regulating valve 48. The two should not be adjusted at the same time.

[0051] Example 2

[0052] An energy-saving gas supply system for a test bench, such as Figure 3 As shown. The system includes a main circuit, which comprises, in sequence, an air filter 41, an air compressor 42, a cooler 43, a main circuit valve 44, a flow meter 45, and a humidifier 46. The humidifier 46 is connected at its end to the cathode inlet of the fuel cell stack 3, and the fuel cell stack 3 is connected to the back pressure valve 49. The system also includes a branch circuit, with its inlet connected between the cooler 43 and the main circuit valve 44, and its outlet connected between the fuel cell stack 3 and the back pressure valve 49. A branch circuit regulating valve 48 is provided on the branch circuit.

[0053] The air compressor 42 is a low-pressure air compressor;

[0054] The fuel cell stack 3 is located outside the test bench;

[0055] A gas detector 47 is also provided between the humidifier 46 and the fuel cell stack 3; used to detect air temperature, pressure and humidity.

[0056] The opening degree of the branch regulating valve 48 is adjustable.

[0057] The energy-saving air supply system of the test bench includes a PLC system, which is connected to an air compressor 42, an air source valve, an air supply valve, a gas detector 47, a main valve 44, a flow meter 45, a humidifier 46, a branch regulating valve 48, and a back pressure valve 49.

[0058] The air compressor is externally mounted near the test bench frame, meaning it is a separate external connection from the main body of the test bench.

[0059] Air compressor 42 is installed outside the test bench frame, 1-5m away from the test bench. A pipe connects air compressor 42 to the main body of the test bench. After connecting to the cooler, air compressor 42 is connected via a pressure-resistant hose supply pipe 431 to reduce vibration caused by airflow and vibration transmission. Air compressor 42 is positioned close to the test bench, near the indoor / outdoor partition 432 of the building. Fresh air is drawn in from outside through the intake pipe 433, passes through the indoor / outdoor partition 432, is compressed by air compressor 42 after passing through air filter 41, and then cooled by cooler 43. The pressure-resistant hose supply pipe 431 delivers the air to the test bench frame. Air used by the fuel cell stack passes through the back pressure valve 49 and exhaust pipe 434 of the test bench, passes through the indoor / outdoor partition 432, and is discharged to the outside of the building.

[0060] Comparative Example 1:

[0061] Test benches, especially for high-power tests, typically use a remote gas supply system outside the test bench, including compression and storage tanks, to deliver high-pressure gas to the test bench via pipelines and valves. The gas pressure is mostly 0.7 MPa, and then depressurized on the test bench to reach the fuel cell at 0.02~0.20 MPa, with a small number possibly using 0.30 MPa. A large proportion of the compression power is wasted.

[0062] like Figure 1As shown, the existing test bench's cathode air supply system 1 mainly consists of an existing air filter 11, a high-pressure air compressor 12, an existing cooler 13, and an air storage tank 14. Through valve control and a pipeline system, air is delivered from a remote location to the test bench's cathode air control system 2. From there, it passes through a gas source valve 21, a pressure reducing valve 22, a gas supply valve 23, a flow controller 24, an existing humidifier 25, and an existing gas detector 26 before reaching the fuel cell stack 3. From the fuel cell stack 3, the air returns to the test bench, where the pressure is controlled by the existing back pressure valve 27 before being released, thus completing the management of the cathode air. The high-pressure air compressor 12 is typically 0.7 MPa, due to pressure losses from the storage tank 15, the long pipeline connecting to the test bench, and the pressure reduction loss from the pressure reducing valve 22.

[0063] Thus, not only is the aforementioned compression work wasted due to the high pressure followed by depressurization, but the gas supply system also occupies a larger area and incurs higher equipment costs, and its layout is limited by the arrangement of pipelines within the building. In high-power testing, the conventional method of remotely connected compression and storage supply exceeds the space, cost, and energy consumption of the system provided by this invention, which uses a low-pressure gas supply method within the test bench itself.

[0064] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. An energy-saving gas supply system for a fuel cell test bench, characterized in that, The test bench includes a main circuit, which comprises an air filter (41), an air compressor (42), a cooler (43), a main circuit valve (44), a flow meter (45), and a humidifier (46) connected in sequence. The end of the humidifier (46) is connected to the cathode inlet of the fuel cell stack (3), and the outlet of the fuel cell stack (3) is connected to the back pressure valve (49). A branch circuit is also provided within the test bench. The inlet connection of the branch circuit is located between the cooler (43) and the main circuit valve (44), and the outlet connection of the branch circuit is located between the cooler (43) and the main circuit valve (44). Between the fuel cell stack (3) and the back pressure valve (49); a branch regulating valve (48) is provided on the branch; the fuel cell stack (3) is located outside the test bench; a gas detector (47) is also provided between the humidifier (46) and the fuel cell stack (3); the air compressor (42) is a low-pressure air compressor; the air compressor (42) is located inside the test bench or outside the test bench at a distance of 1-5m; the maximum pressure of the rated flow of the low-pressure air compressor (42) is 0.4~0.50MPag; When low-flow surge occurs, maintain the speed of the air compressor (42), open the branch regulating valve (48), and part of the gas flow is diverted from the branch to the back pressure valve (49) on the fuel cell tail gas discharge line section. The fuel cell (3) flow is detected by the main flow meter (45) and used as the basis for controlling the opening of the branch regulating valve (48) to reduce the fuel cell (3) flow to the required value. For a specific flow rate, when the flow rate exceeds 150% of the surge zone flow rate, the flow rate of the fuel cell stack (3) needs to be adjusted. According to the working curve of the air compressor (42), the speed of the air compressor (42) operates according to the characteristic curve. When the flow rate is below 150% of the surge zone flow rate, the air compressor (42) speed remains unchanged. First, adjust the opening of the branch regulating valve (48) so that the flow meter (45) data is the system operation setting data. Then, adjust the back pressure valve (49) to adjust the operating pressure to the set pressure. Then, adjust the branch regulating valve (48) again.

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