Fuel cell system based on atomization humidifying mode and humidity adjusting method thereof

Abstract

The invention relates to a fuel cell system based on an atomization humidifying mode and a humidity adjusting method thereof. The fuel cell system comprises an electric pile, a hydrogen supply subsystem and an oxygen supply subsystem, a hydrogen source of the hydrogen supply subsystem is sequentially connected with a proportional valve, an ejector and an anode inlet of a galvanic pile, an anode outlet of the galvanic pile is connected with a water segregator, and a gas outlet of the water segregator is connected with the ejector; a first outlet of an air compressor of the oxygen supply subsystem is sequentially connected with a mixing chamber and a cathode inlet of an electric pile, and a second outlet of the air compressor is connected with a gas inlet of an atomizer; a cathode outlet of the electric pile is connected with a tail gas exhaust pipeline; a liquid inlet of the water collecting tank is connected with a liquid outlet of the water segregator, and a liquid outlet of the water collecting tank is sequentially connected with the atomizing water pump, the atomizer and the mixing chamber. The air inlet flow and the air inlet pressure are controlled in an atomization humidifying mode, active adjustment of humidity under variable working conditions is achieved, on one hand, prolonging of the service life of the galvanic pile is facilitated, better galvanic pile water management is achieved, and on the other hand, a solution is provided for accurate humidity control.

Description

Technical Field

[0001] The present invention relates to the field of fuel cells, and in particular to a fuel cell system based on an atomization humidification mode and a humidity regulation method thereof. Background Art

[0002] In fuel cell systems, air inlet humidification is an important way to solve the water and heat management of the fuel cell stack. The existing technologies mainly include bubbling humidification, membrane humidification and other methods. However, in vehicle-mounted application scenarios, membrane humidification is still the main method, and bubbling humidification is mostly suitable for laboratories.

[0003] The principle of the membrane humidification method is that the humidified gas at the air outlet enters the air inlet through the membrane reverse osmosis to humidify the air at the air inlet. The membrane humidification method is a passive control, and the adjustment of humidity depends on the number of membrane tubes. For vehicle-mounted variable load conditions, the humidity required for different conditions is different, so the membrane humidification method cannot adapt to vehicle-mounted variable load conditions in a friendly manner. Therefore, it is necessary to provide a humidification device with actively adjustable humidity based on the vehicle-mounted scenario, specifically, to provide a fuel cell system based on atomization humidification and a humidity adjustment method thereof to solve the problems existing in the above-mentioned existing prior art. Summary of the invention

[0004] In view of this, the present invention provides a fuel cell system based on atomization humidification and a humidity control method thereof, with the aim of providing a humidifying device with actively adjustable humidity to achieve active adjustment of humidity under variable operating conditions, thereby increasing the life of the fuel cell stack and achieving better fuel cell stack water management.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A fuel cell system based on atomization humidification mode, the fuel cell system comprising a fuel cell stack, a hydrogen supply subsystem, and an oxygen supply subsystem;

[0007] The hydrogen supply subsystem includes a hydrogen source, a proportional valve, an ejector, and a water separator. The hydrogen source is sequentially connected to the proportional valve, the ejector, and the anode inlet of the stack. The anode outlet of the stack is connected to the water separator. The gas outlet of the water separator is connected to the ejector.

[0008] The oxygen supply subsystem includes an air compressor, a mixing chamber, an atomizer, a spray water pump, and a water collecting tank. The first outlet of the air compressor is connected to the mixing chamber and the cathode inlet of the fuel cell stack in sequence, and the second outlet of the air compressor is connected to the gas inlet of the atomizer; the cathode outlet of the fuel cell stack is connected to the tail exhaust pipe; the liquid inlet of the water collecting tank is connected to the liquid outlet of the water distributor, and the liquid outlet of the water collecting tank is connected to the spray water pump, the atomizer, and the mixing chamber in sequence.

[0009] Furthermore, the mixing chamber is used for humidifying the gas entering the pile. In the mixing chamber, the high-temperature air flowing out of the first outlet of the air compressor is used to gasify the droplets sprayed by the atomizer and then evenly mix them with the air.

[0010] Furthermore, a back pressure valve is provided on the tail exhaust pipe connected to the cathode outlet of the fuel cell stack.

[0011] Furthermore, an air flow meter is provided at the inlet of the air compressor; a first pressure sensor is provided at the cathode inlet of the fuel cell stack; a second pressure sensor is provided on the pipeline between the spray water pump and the atomizer; a temperature and humidity sensor is provided at the outlet of the mixing chamber; a first temperature sensor is provided at the outlet of the cooling path of the fuel cell stack; and a second temperature sensor is provided at the inlet of the cooling path of the fuel cell stack.

[0012] The present invention also provides a humidity adjustment method based on the above fuel cell system, and the humidity adjustment method is specifically as follows:

[0013] When the fuel cell system is running, the liquid water separated by the water separator in the hydrogen supply subsystem enters the water collecting tank, and the liquid water in the water collecting tank enters the atomizer under the action of the spray water pump;

[0014] The air is compressed by the air compressor to produce high-temperature air, a small part of which flows out through the second outlet of the air compressor and enters the atomizer to atomize the liquid water in the atomizer into smaller droplets; most of the high-temperature air flows out through the first outlet of the air compressor and enters the mixing chamber. In the mixing chamber, the high-temperature air flowing out of the first outlet of the air compressor is used to vaporize the droplets sprayed by the atomizer, and then evenly mix with the air to humidify the air entering the pile;

[0015] Control the speed of the spray pump to maintain P 雾化 -P 进 =20kPa, to ensure that the atomizer can continuously atomize, P 雾化 is the gas pressure in the pipeline between the spray water pump and the atomizer, which is measured by the second pressure sensor arranged on the pipeline between the spray water pump and the atomizer, P 进 is the gas pressure at the air inlet of the stack, measured by a first pressure sensor disposed at the cathode inlet of the stack;

[0016] When the air stoichiometric ratio λ remains unchanged, the stack air inlet gas pressure P is calculated. 进 The value range of

[0017] Adjust the air inlet humidity RH. For a fixed system, each operating point has an optimal humidity value. Set the target RH according to the operating conditions. 实际 , get the humidity value RH fed back from the temperature and humidity sensor 实际 , compared with RH 实际 and RH 实际, humidity is adjusted according to the comparison results.

[0018] Furthermore, when the air stoichiometric ratio λ remains unchanged, the stack air inlet gas pressure P is calculated. 进 The value range of is as follows:

[0019] Calculate the maximum value of the stack air inlet gas pressure To maintain P 雾化 -P 进 =20kPa, P 雾化 Increase, P 进 Also increases, when the atomizing water pump reaches the maximum speed, P 雾化 Reaching the maximum value, corresponding to P 进 It also reaches the maximum value, that is, when the atomizing water pump reaches the highest speed, the maximum value of the stack air inlet gas pressure is calculated

[0020] Furthermore, when the air stoichiometric ratio λ remains unchanged, the stack air inlet gas pressure P is calculated. 进 The value range of , the specific method is as follows:

[0021] Calculate the minimum value of the stack air inlet gas pressure The calculation formula is as follows:

[0022]

[0023] Where, λ is the air stoichiometric ratio; k is the stack flow resistance coefficient; I is the working current of the stack; N is the number of cells in the stack; F is the Faraday constant; M 空气 is the molar mass of air; T 出 is the coolant temperature at the outlet of the cooling path of the fuel cell stack;

[0024] P 进 As the air stoichiometric ratio λ increases, for a fixed λ, the minimum value of the stack inlet gas pressure is calculated by formula (1):

[0025] Stack air inlet gas pressure P 进 The value range is

[0026] Further, the comparison RH 实际 and RH 实际 , humidity adjustment is performed according to the comparison results, as follows:

[0027] When RH 实际 =RH 目标 When the current operating conditions are maintained;

[0028] When RH实际 <RH 目标 When the air metering ratio λ remains unchanged, the back pressure valve opening is increased, the air compressor speed is reduced, and thus P 进 , until the target humidity is met; if P is reduced 进 to If the intake air humidity requirement is still not met, the cathode intake air flow rate is reduced, that is, the air stoichiometric ratio λ is reduced, thereby further reducing Until the target humidity can be met;

[0029] When RH 实际 >RH 目标 When the air metering ratio λ remains unchanged, the back pressure valve opening is reduced, the air compressor speed is increased, and P is gradually increased. 进 , until the target humidity is met; if P is increased 进 to If the intake humidity requirement is still not met, set At this time, the highest humidity that can be controlled is reached.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) By setting a mixing chamber at the rear end of the air compressor and using an atomizer in the mixing chamber to humidify the air entering the reactor, the traditional membrane humidifier is replaced to reduce the cost of the fuel cell; by setting an air compressor with two outlets, a small part of the high-temperature air compressed by the air compressor is used to flow out through the second outlet of the air compressor into the atomizer to atomize the liquid water in the atomizer into smaller droplets; while most of the high-temperature air flows out through the first outlet of the air compressor into the mixing chamber. In the mixing chamber, the high-temperature air flowing out of the first outlet of the air compressor is used to vaporize the droplets sprayed by the atomizer, and then evenly mix with the air to humidify the air entering the reactor.

[0032] (2) By setting up a water collecting tank to collect the liquid water separated by the water separator in the hydrogen supply subsystem, liquid water is provided to the atomizer, and the water produced by the fuel cell stack is fully utilized to achieve self-humidification of the fuel cell; at the same time, the gas pressure P at the inlet of the fuel cell stack is determined by accurate formula calculation. 进 The value range is set according to the working conditions. 实际 , get the humidity value RH fed back from the temperature and humidity sensor 实际 , compared with RH 实际 and RH 实际 , and adjust the humidity according to the comparison results. By controlling the intake flow and intake pressure through atomization humidification, the active adjustment of humidity under variable working conditions is achieved. On the one hand, it is beneficial to increase the life of the fuel cell stack and achieve better fuel cell stack water management. On the other hand, it provides a solution for precise humidity control.

[0033] Other features and advantages of the present invention will be described in the following description, and partly become obvious from the description, or be understood by implementing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0035] Figure 1 A schematic structural diagram of a fuel cell system based on an atomization humidification method according to an embodiment of the present invention is shown.

[0036] In the figure: 1. Hydrogen source; 2. Proportional valve; 3. Ejector; 4. Fuel cell; 5. Water distributor; 6. Water collecting tank; 7. Spray water pump; 8. Atomizer; 9. Air compressor; 10. Mixing chamber; 11. Back pressure valve; 12. Second temperature sensor; 13. First temperature sensor; 14. Temperature and humidity sensor; 15. First pressure sensor; 16. Second pressure sensor; 17. Air flow meter. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] The embodiment of the present invention proposes a fuel cell system based on atomization humidification method, as shown in the attached Figure 1 As shown, the fuel cell system includes a fuel cell stack 4, a hydrogen supply subsystem, and an oxygen supply subsystem;

[0039] The hydrogen supply subsystem comprises a hydrogen source 1, a proportional valve 2, an ejector 3, and a water separator 5. The hydrogen source 1 is connected to the proportional valve 2, the ejector 3, and the anode inlet of the stack 4 in sequence. The anode outlet of the stack 4 is connected to the water separator 5. The gas outlet of the water separator 5 is connected to the ejector 3.

[0040] The oxygen supply subsystem includes an air compressor 9, a mixing chamber 10, an atomizer 8, a spray water pump 7, and a water collecting tank 6. The first outlet of the air compressor 9 is connected to the mixing chamber 10 and the cathode inlet of the fuel cell stack 4 in sequence, and the second outlet of the air compressor 9 is connected to the gas inlet of the atomizer 8; the cathode outlet of the fuel cell stack 4 is connected to the tail exhaust pipe; the liquid inlet of the water collecting tank 6 is connected to the liquid outlet of the water distributor 5, and the liquid outlet of the water collecting tank 6 is connected to the spray water pump 7, the atomizer 8 and the mixing chamber 10 in sequence.

[0041] The mixing chamber 10 is used for humidifying the gas entering the stack. In the mixing chamber 10, the high-temperature air flowing out of the first outlet of the air compressor 9 is used to vaporize the droplets sprayed by the atomizer 8 and then evenly mix with the air to meet the demand for humidifying the air entering the stack.

[0042] A back pressure valve 11 is provided on the tail pipe connected to the cathode outlet of the stack 4. By adjusting the rotation speed of the air compressor 9 and the opening of the back pressure valve 11, the air flow rate and the intake pressure entering the stack can be controlled simultaneously.

[0043] An air flow meter 17 is provided at the inlet of the air compressor 9 for detecting the air flow entering the stack; a first pressure sensor 15 is provided at the cathode inlet of the fuel cell stack 4; a second pressure sensor 16 is provided on the pipeline between the spray water pump 7 and the atomizer 8; a temperature and humidity sensor 14 is provided at the outlet of the mixing chamber 10 for detecting the humidity of the air entering the stack; a first temperature sensor 13 is provided at the outlet of the cooling path of the fuel cell stack 4; and a second temperature sensor 12 is provided at the inlet of the cooling path of the fuel cell stack 4.

[0044] The embodiment of the present invention further provides a humidity adjustment method for a fuel cell system based on an atomization humidification method, and the humidity adjustment method is specifically as follows:

[0045] When the fuel cell system is running, the liquid water separated by the water separator 5 in the hydrogen supply subsystem enters the water collecting tank 6, and the liquid water in the water collecting tank 6 enters the atomizer 8 under the action of the spray water pump 7;

[0046] The air is compressed by the air compressor 9 to produce high-temperature air, a small portion of which flows out through the second outlet of the air compressor 9 and enters the atomizer 8 to atomize the liquid water in the atomizer 8 into smaller droplets; most of the high-temperature air flows out through the first outlet of the air compressor 9 and enters the mixing chamber 10. In the mixing chamber 10, the high-temperature air flowing out of the first outlet of the air compressor 9 is used to gasify the droplets sprayed by the atomizer 8, and then evenly mixes with the air to humidify the air entering the pile;

[0047] Control the speed of the spray pump 7 to maintain P 雾化 -P 进 =20kPa, to ensure that the atomizer can continuously atomize without interruption, P 雾化is the gas pressure in the pipeline between the spray water pump 7 and the atomizer 8, measured by the second pressure sensor 16 disposed on the pipeline between the spray water pump 7 and the atomizer 8, P 进 is the gas pressure at the air inlet of the stack, measured by the first pressure sensor 15 disposed at the cathode inlet of the stack 4;

[0048] When the air stoichiometric ratio λ remains unchanged, the stack air inlet gas pressure P is calculated. 进 The value range of

[0049] Adjust the air inlet humidity RH. For a fixed system, each operating point has an optimal humidity value. Set the target RH according to the operating conditions. 实际 , obtain the humidity value RH fed back by the temperature and humidity sensor 14 实际 , compared with RH 实际 and RH 实际 , humidity is adjusted according to the comparison results.

[0050] When the air stoichiometric ratio λ remains unchanged, calculate the stack air inlet gas pressure P 进 The value range of is as follows:

[0051] Calculate the maximum value of the stack air inlet gas pressure To maintain P 雾化 -P 进 =20kPa, P 雾化 Increase, P 进 As the speed increases, when the atomizing water pump 7 reaches the maximum speed, P 雾化 Reaching the maximum value, corresponding to P 进 When the atomizing pump 7 reaches the maximum speed, the maximum value of the stack air inlet gas pressure is calculated.

[0052] Calculate the minimum value of the stack air inlet gas pressure The calculation formula is as follows:

[0053]

[0054] Where, λ is the air stoichiometric ratio; k is the stack flow resistance coefficient; I is the working current of the stack; N is the number of cells in the stack; F is the Faraday constant; M 空气 is the molar mass of air; T 出 is the coolant temperature at the outlet of the cooling path of the fuel cell stack;

[0055] From formula (1), we can see that for a fixed fuel cell system, the number of cells N in the stack is fixed; the stack flow resistance coefficient k depends on the size of the stack flow field and is a fixed value; under a certain fixed working condition, the working current I of the stack is fixed; generally speaking, the coolant temperature T at the outlet of the cooling path of the stack is 出 is fixed and depends on the heat dissipation requirements of the cooling system. 进 As the air stoichiometric ratio λ increases, for a fixed λ, the minimum value of the stack inlet gas pressure is calculated by formula (1): To ensure that the collected liquid water meets the requirements of humidification;

[0056] Stack air inlet gas pressure P 进 The value range is

[0057] The derivation process of formula (1) is as follows:

[0058] In the fuel cell system, the hydrogen loop is circulated and the air loop is exhausted to the outside. From the perspective of satisfying water balance, the following expression exists:

[0059] Q 空进 +Q 生成 =Q 空出 +Q 氢出 (2);

[0060] In the formula, Q 空进 is the water mass flow rate at the air inlet; Q 空出 is the water mass flow rate at the air outlet; Q 生成 Q is the mass flow rate of water generated by the stack reaction; 氢出 is the water mass flow rate at the hydrogen outlet.

[0061] In order to meet the normal requirements of system operation, that is, the liquid water collected by the hydrogen water separator is greater than the water required for air humidification, the following expression exists:

[0062] Q 氢出 ≥Q 空进 (3);

[0063] Substituting formula (2) into formula (3), we can obtain:

[0064] Q 生成 ≥Q 空出 (4);

[0065] For the air outlet, there is an expression for the ratio of the mass of water to the mass of air as follows:

[0066]

[0067] In the formula, m 空出is the air mass flow rate at the air outlet; P 水出 is the partial pressure of water at the air outlet; P 空出 M is the pressure of the air at the air outlet; 水 is the molar mass of water; M 空气 is the molar mass of air.

[0068] For the air tail exhaust, the mass flow rate of the air outlet is the mass flow rate of the air inlet minus the mass flow rate of oxygen consumed by the reaction, that is:

[0069]

[0070] Where, λ is the air stoichiometric ratio; I is the working current of the battery stack; N is the number of cells in the battery stack; F is the Faraday constant; M 空气 is the molar mass of air.

[0071] The mass flow rate Q of water generated by the stack reaction 生成 , which is related to the current working current, has the following expression:

[0072]

[0073] And there is the following relationship, air outlet gas pressure P 出 is the partial pressure of water at the air outlet P 水出 The air pressure at the air outlet is P 空出 sum:

[0074] P 出 =P 空出 +P 水出 (8);

[0075] Substituting formulas (5), (6), (7), and (8) into formula (4), we can obtain:

[0076]

[0077] For the air inlet air mass flow rate m 空进 There are the following expressions:

[0078]

[0079] For a fixed model of battery stack, the size of the flow field is fixed, and the air inlet gas pressure P 进 and air outlet gas pressure P 出 There is a certain relationship, which is expressed as follows:

[0080] P 进 =k*m 空进 +P 出 (11);

[0081] Where k is the stack resistance coefficient.

[0082] Partial pressure of water at air outlet P 水出 The coolant temperature T at the outlet of the stack cooling path 出 The details are as follows:

[0083] P 水出 =0.5124*T 出 -152.55 (12);

[0084] Substituting formulas (10), (11), and (12) into formula (9), we can obtain formula (1):

[0085]

[0086] The comparative RH 实际 and RH 实际 , humidity adjustment is performed according to the comparison results, as follows:

[0087] When RH 实际 =RH 目标 When the current operating conditions are maintained;

[0088] When RH 实际 <RH 目标 When the air metering ratio λ remains unchanged, the back pressure valve opening is increased, the air compressor speed is reduced, and thus P 进 , until the target humidity is met; if P is reduced 进 to If the intake air humidity requirement is still not met, the cathode intake air flow rate is reduced, that is, the air stoichiometric ratio λ is reduced, thereby further reducing Until the target humidity can be met;

[0089] When RH 实际 >RH 目标 When the air metering ratio λ remains unchanged, the back pressure valve opening is reduced, the air compressor speed is increased, and P is gradually increased. 进 , until the target humidity is met; if P is increased 进 to If the intake humidity requirement is still not met, set At this time, the highest humidity that can be controlled is reached.

[0090] The present application provides a mixing chamber at the rear end of the air compressor, and uses an atomizer in the mixing chamber to humidify the air entering the stack, thereby replacing the traditional membrane humidifier and reducing the cost of the fuel cell. An air compressor with two outlets is provided, and a small part of the high-temperature air compressed by the air compressor is used to flow out through the second outlet of the air compressor into the atomizer, and the liquid water in the atomizer is atomized into smaller droplets; while most of the high-temperature air flows out through the first outlet of the air compressor into the mixing chamber. In the mixing chamber, the high-temperature air flowing out of the first outlet of the air compressor is used to vaporize the droplets sprayed by the atomizer, and then evenly mix with the air to humidify the air entering the stack.

[0091] By setting up a water collecting tank to collect the liquid water separated by the water separator in the hydrogen supply subsystem, liquid water is provided to the atomizer, and the water produced by the fuel cell stack is fully utilized to achieve self-humidification of the fuel cell; at the same time, the gas pressure P at the inlet of the fuel cell stack is determined by accurate formula calculation. 进 The value range is set according to the working conditions. 实际 , get the humidity value RH fed back from the temperature and humidity sensor 实际 , compared with RH 实际 and RH 实际 , and adjust the humidity according to the comparison results. By controlling the intake flow and intake pressure through atomization humidification, the active adjustment of humidity under variable working conditions is achieved. On the one hand, it is beneficial to increase the life of the fuel cell stack and achieve better fuel cell stack water management. On the other hand, it provides a solution for precise humidity control.

[0092] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A fuel cell system based on atomization humidification method, characterized in that: The fuel cell system comprises a fuel cell stack (4), a hydrogen supply subsystem, and an oxygen supply subsystem; The hydrogen supply subsystem comprises a hydrogen source (1), a proportional valve (2), an ejector (3), and a water separator (5); the hydrogen source (1) is connected in sequence to the proportional valve (2), the ejector (3), and an anode inlet of the fuel cell stack (4); the anode outlet of the fuel cell stack (4) is connected to the water separator (5); and the gas outlet of the water separator (5) is connected to the ejector (3); The oxygen supply subsystem comprises an air compressor (9), a mixing chamber (10), an atomizer (8), a spray water pump (7), and a water collecting tank (6); a first outlet of the air compressor (9) is connected to the mixing chamber (10) and the cathode inlet of the fuel cell stack (4) in sequence; a second outlet of the air compressor (9) is connected to the gas inlet of the atomizer (8); the cathode outlet of the fuel cell stack (4) is connected to the tail exhaust pipe; a liquid inlet of the water collecting tank (6) is connected to the liquid outlet of the water distributor (5); and a liquid outlet of the water collecting tank (6) is connected to the spray water pump (7), the atomizer (8), and the mixing chamber (10) in sequence.

2. The fuel cell system based on atomization humidification method as claimed in claim 1, characterized in that: The mixing chamber (10) is used to humidify the gas entering the pile. In the mixing chamber (10), the high-temperature air flowing out of the first outlet of the air compressor (9) is used to gasify the droplets sprayed by the atomizer (8) and then uniformly mix them with the air.

3. The fuel cell system based on atomization humidification method as claimed in claim 2, characterized in that: A back pressure valve (11) is provided on the tail exhaust pipe connected to the cathode outlet of the fuel cell stack (4).

4. The fuel cell system based on atomization humidification method as claimed in claim 3, characterized in that: An air flow meter (17) is provided at the inlet of the air compressor (9); a first pressure sensor (15) is provided at the cathode inlet of the fuel cell stack (4); a second pressure sensor (16) is provided on the pipeline between the spray water pump (7) and the atomizer (8); a temperature and humidity sensor (14) is provided at the outlet of the mixing chamber (10); a first temperature sensor (13) is provided at the outlet of the cooling path of the fuel cell stack (4); and a second temperature sensor (12) is provided at the inlet of the cooling path of the fuel cell stack (4).

5. A humidity adjustment method for a fuel cell system according to any one of claims 1 to 4, characterized in that: The humidity adjustment method is as follows: When the fuel cell system is running, the liquid water separated by the water separator (5) in the hydrogen supply subsystem enters the water collecting tank (6), and the liquid water in the water collecting tank (6) enters the atomizer (8) under the action of the spray water pump (7); The air is compressed by the air compressor (9) to produce high-temperature air, a small portion of which flows out through the second outlet of the air compressor (9) and enters the atomizer (8) to atomize the liquid water in the atomizer (8) into smaller droplets; the majority of the high-temperature air flows out through the first outlet of the air compressor (9) and enters the mixing chamber (10), in which the droplets sprayed by the atomizer (8) are vaporized by the high-temperature air flowing out of the first outlet of the air compressor (9), and then uniformly mixed with the air to humidify the air entering the pile; Control the speed of the spray pump (7) to maintain P 雾化 -P 进 =20kPa, to ensure that the atomizer can continuously atomize, P 雾化 is the gas pressure in the pipeline between the spray water pump (7) and the atomizer (8), measured by a second pressure sensor (16) arranged on the pipeline between the spray water pump (7) and the atomizer (8), P 进 is the gas pressure at the air inlet of the fuel cell stack, measured by a first pressure sensor (15) arranged at the cathode inlet of the fuel cell stack (4); When the air stoichiometric ratio λ remains unchanged, the stack air inlet gas pressure P is calculated. 进 The value range of Adjust the air inlet humidity RH. For a fixed system, each operating point has an optimal humidity value. Set the target RH according to the operating conditions. 实际 , obtain the humidity value RH fed back from the temperature and humidity sensor (14) 实际 , compared with RH 实际 and RH 实际 , and adjust the humidity based on the comparison results.

6. The humidity adjustment method according to claim 5, characterized in that: When the air stoichiometric ratio λ remains unchanged, the stack air inlet gas pressure P is calculated. 进 The value range of is as follows: Calculate the maximum value of the stack air inlet gas pressure To maintain P 雾化 -P 进 =20kPa, P 雾化 Increase, P 进 When the atomizing water pump (7) reaches the maximum speed, P 雾化 Reaching the maximum value, corresponding to P 进 It also reaches the maximum value, that is, when the atomizing water pump (7) reaches the maximum speed, the maximum value of the gas pressure at the air inlet of the stack is calculated.

7. The humidity adjustment method according to claim 6, characterized in that: When the air stoichiometric ratio λ remains unchanged, the stack air inlet gas pressure P is calculated. 进 The value range of , the specific method is as follows: Calculate the minimum value of the stack air inlet gas pressure The calculation formula is as follows: Where, λ is the air stoichiometric ratio; k is the stack flow resistance coefficient; I is the working current of the stack; N is the number of cells in the stack; F is the Faraday constant; M 空气 is the molar mass of air; T 出 is the coolant temperature at the outlet of the cooling path of the fuel cell stack; P 进 As the air stoichiometric ratio λ increases, for a fixed λ, the minimum value of the stack inlet gas pressure is calculated by formula (1): Stack air inlet gas pressure P 进 The value range is 8. The humidity adjustment method according to claim 7, characterized in that: The comparative RH 实际 and RH 实际 , humidity adjustment is performed according to the comparison results, as follows: When RH 实际 =RH 目标 When the current operating conditions are maintained; When RH 实际 <RH 目标 When the air metering ratio λ remains unchanged, the back pressure valve opening is increased, the air compressor speed is reduced, and thus P 进 , until the target humidity is met; if the If the intake air humidity requirement is still not met, the cathode intake air flow rate is reduced, that is, the air stoichiometric ratio λ is reduced, thereby further reducing Until the target humidity is met; When RH 实际 >RH 目标 When the air metering ratio λ remains unchanged, the back pressure valve opening is reduced, the air compressor speed is increased, and P is gradually increased. 进 , until the target humidity is met; if P is increased 进 to If the intake humidity requirement is still not met, set At this time, the highest humidity that can be controlled is reached.

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