A fuel cell system, a fuel cell air system, and a control method

Abstract

The application discloses a fuel cell air system, a control method and a fuel cell system, which comprise an air compressor, an expander, an air outlet and a tail exhaust pipeline, an air inlet pipeline, an air combination valve connected in series on the air inlet pipeline, an air inlet and a first air outlet of the air combination valve connected in series on the air inlet pipeline, a second air outlet of the air combination valve connected to an air inlet of the expander, an air exhaust pipeline, a water separator and a back pressure valve connected in series on the air exhaust pipeline, a drain pipeline, one end of which is connected to a drain hole of the water separator and the other end of which is connected to the tail exhaust pipeline, and a bypass valve connected in series on the drain pipeline. The application can control different working states of the valves to make the fuel cell air system work in different modes, meet the working requirements of the fuel cell air system in different working scenes and finally achieve the purpose that the expander can be started smoothly and operated reliably at low temperature.

Description

Technical Field

[0001] This invention relates to the field of fuel cell system technology, and in particular to a fuel cell system, a fuel cell air system, and a control method. Background Technology

[0002] Using green, low-carbon, and widely available energy sources is of great significance. Hydrogen energy, as a secondary energy source, is abundant in the universe, with hydrogen accounting for 75% of the total elemental composition. Its calorific value is three times that of gasoline, and it produces no carbon after combustion or electrochemical reaction. Therefore, it is receiving increasing attention and promotion both domestically and internationally.

[0003] Fuel cell systems, as an important tool for using hydrogen energy, are gradually being widely used in long-distance heavy-duty road transportation, rail transportation, ships, airplanes, independent power sources, combined heat and power, and light vehicles (such as two-wheeled vehicles and three-wheeled vehicles) due to their advantages such as high efficiency (theoretical efficiency can reach more than 80%), zero emissions and no pollution (the only product is water), good low temperature adaptability (can be used normally at -10℃), and fast energy replenishment speed.

[0004] Currently, fuel cell systems both domestically and internationally are developing towards higher power and higher efficiency. A common approach is to add an expander to the air compressor. The expander effectively recovers energy from the gas exiting the fuel cell stack on the air side, thereby reducing power consumption of system accessories and improving system efficiency.

[0005] The biggest challenge facing expanders in current practical applications is ensuring their reliability at low temperatures. This is because the gas passing through the expander contains a large amount of water vapor mixture; incomplete purging of this mixture can cause the expander to freeze at low temperatures. Additionally, during low-temperature startup, ice particles may escape from the fuel cell stack's air-side outlet and enter the expander with the airflow, posing a risk of damaging the expander blades.

[0006] Therefore, how to ensure that the expander can start up smoothly and operate reliably at low temperatures is a technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0007] In view of this, the purpose of the present invention is to provide a fuel cell air system to ensure that the expander can start up smoothly and operate reliably at low temperatures;

[0008] Another object of the present invention is to provide a fuel cell system having the above-described fuel cell air system and a fuel cell air system control method.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] A fuel cell air system, comprising:

[0011] Air compressor;

[0012] An expander is connected to the air compressor via a drive, and the air outlet of the expander is connected to the tailpipe.

[0013] An air intake pipe is connected at one end to the outlet of the air compressor and at the other end to the air inlet of the fuel cell stack. An air combination valve is connected in series on the air intake pipe. The air inlet and the first air outlet of the air combination valve are connected in series on the air intake pipe. The second air outlet of the air combination valve is connected to the air inlet of the expander. The opening degree of the first air outlet and the second air outlet of the air combination valve is adjustable.

[0014] An air exhaust pipe is connected at one end to the air outlet of the fuel cell stack and at the other end to the air inlet of the expander. A water distributor and a back pressure valve are connected in series on the air exhaust pipe.

[0015] The drainage pipe has one end connected to the drainage hole of the water distributor and the other end connected to the tailpipe. A bypass valve is connected in series on the drainage pipe.

[0016] Optionally, the above-mentioned fuel cell air system also includes a control system. The fuel cell air system includes a first operating mode. In the first operating mode, the control system controls the first air outlet and the second air outlet of the air combination valve to be in the open state, the back pressure valve to be in the closed state, and the bypass valve to be in the open state.

[0017] Optionally, in the above-mentioned fuel cell air system, the control system is used to activate the first operating mode when the water temperature in the fuel cell cooling circuit is lower than a first preset temperature.

[0018] Optionally, in the above-mentioned fuel cell air system, the fuel cell air system includes a second operating mode. In the second operating mode, the control system controls the first air outlet of the air combination valve to be closed, the second air outlet to be open, the back pressure valve to be closed, and the bypass valve to be closed.

[0019] Optionally, in the above-described fuel cell air system, the control system activates the second operating mode when the fuel cell system is started and / or shut down.

[0020] Optionally, in the above-mentioned fuel cell air system, when the fuel cell system is started and the water temperature of the fuel cell cooling circuit is lower than the first preset temperature, the control system controls the start of the second working mode, and after a first preset time, controls the start of the first working mode.

[0021] Optionally, in the above-mentioned fuel cell air system, the fuel cell air system includes a third operating mode. In the third operating mode, the control system controls the first air outlet of the air combination valve to be open, the second air outlet to be closed, the back pressure valve to be open, and the bypass valve to be open.

[0022] Optionally, in the above-mentioned fuel cell air system, when the fuel cell system is started and the water temperature of the fuel cell cooling circuit is not lower than the first preset temperature, the control system controls the start of the second working mode, and after a second preset time, controls the start of the third working mode.

[0023] When the fuel cell system is started and the water temperature in the fuel cell cooling circuit is lower than the first preset temperature, the control system controls the start of the second working mode, and after a first preset time, controls the start of the first working mode, and after the preset conditions are met, controls the start of the third working mode.

[0024] Optionally, in the above-mentioned fuel cell air system, the preset condition is: the water temperature of the fuel cell cooling circuit is higher than the second preset temperature; wherein, the fuel cell system starts when the second preset temperature is not lower than the first preset temperature.

[0025] Optionally, in the above-mentioned fuel cell air system, during the purging of the fuel cell air system, the control system controls the activation of the first working mode, and after a third preset time, controls the activation of the second working mode.

[0026] Optionally, in the above-mentioned fuel cell air system, the air combination valve, back pressure valve, and bypass valve are all dynamically adjustable valves.

[0027] The fuel cell air system provided by this invention includes an air compressor that provides the required air volume to the fuel cell stack, and an expander that partially recovers the energy of the air outlet gas from the fuel cell stack, thereby reducing the power consumption of system accessories and improving system efficiency. An air combination valve is installed on the air intake pipe, with its air inlet and first air outlet connected in series, and its second air outlet connected to the expander's air inlet. The air combination valve is a one-inlet, two-outlet valve, and its opening degree can be adjusted to distribute the flow rates of the first and second air outlets. A water separator and a back pressure valve are installed on the air exhaust pipe. The water separator can partially separate the liquid water from the air outlet of the fuel cell stack, and the separated liquid water can be discharged to the tailpipe through a drain pipe. When the gas from the fuel cell stack's air outlet mainly passes through the back pressure valve, the air inlet pressure of the fuel cell stack can be adjusted by changing the opening degree of the back pressure valve. When the gas from the fuel cell stack's air outlet mainly passes through the bypass valve, the air inlet pressure of the fuel cell stack can be adjusted by changing the opening degree of the bypass valve, and the bypass valve also has the function of discharging liquid water from inside the water separator.

[0028] During low-temperature startup, both the first and second air outlets of the air combination valve can be opened, the back pressure valve closed, and the bypass valve opened. A portion of the air drawn in by the air compressor flows directly to the expander's air inlet after passing through the second air outlet of the air combination valve. This heats the expander and effectively prevents gas backflow from the expander's air outlet due to the back pressure valve being blocked, thus avoiding the expander absorbing ice particles or hydrogen from the exhaust pipe. A portion of the air drawn in by the air compressor flows through the first air outlet of the air combination valve to the fuel cell stack, then to the bypass valve, and finally, together with the liquid water from the fuel cell stack's air outlet, is discharged into the system's exhaust pipe.

[0029] By adopting the valve opening method described above, it is possible to prevent the liquid water generated on the air side of the fuel cell stack from freezing during the low-temperature start-up process. This is because the fuel cell stack is still at a low temperature. The liquid water at the air outlet of the fuel cell stack may freeze into ice particles as it flows to the air outlet of the fuel cell stack, or the liquid water at the air outlet of the fuel cell stack may freeze into ice particles as it passes through the system's metal valves / connectors. These ice particles may then enter the expander with the airflow, damaging the expander blades and reducing the reliability of the system.

[0030] If the back pressure valve freezes at low temperatures, the valve opening method described above can support normal system operation. During system operation, the high-temperature gas from the fuel cell stack's air outlet heats the valve plate, allowing it to thaw quickly and return to normal operation.

[0031] This invention can control the different working states of each valve so that the fuel cell air system can operate in different modes, meet the working requirements of the fuel cell air system in different working scenarios, and ultimately achieve the goal of enabling the expander to start smoothly and operate reliably at low temperatures.

[0032] A fuel cell system comprising a fuel cell air system as described in any of the preceding claims.

[0033] The fuel cell system disclosed in this invention, having the aforementioned fuel cell air system, possesses all the technical effects of the aforementioned fuel cell air system, which will not be elaborated upon here.

[0034] A fuel cell air system control method, utilizing the fuel cell air system as described in any of the preceding claims, includes a low-temperature start-up step, a normal-temperature start-up step, and a purging step;

[0035] The low-temperature start-up step is as follows: when the water temperature in the fuel cell cooling circuit is lower than the first preset temperature, the second working mode is started, and after a first preset time, the first working mode is started; when the water temperature in the fuel cell cooling circuit is higher than the second preset temperature, the third working mode is started, and the second preset temperature is not lower than the first preset temperature.

[0036] The normal temperature start-up step is as follows: start the second working mode, and after a second preset time, start the third working mode;

[0037] The purging steps are as follows: start the first working mode, and after a third preset time, start the second working mode;

[0038] When in the second working mode, the first air outlet of the air combination valve is closed, the second air outlet is open, the back pressure valve is closed, and the bypass valve is closed.

[0039] When in the first working mode, both the first air outlet and the second air outlet of the air combination valve are in the open state, the back pressure valve is in the closed state, and the bypass valve is in the open state.

[0040] When in the third working mode, the first air outlet of the air combination valve is open, the second air outlet is closed, the back pressure valve is open, and the bypass valve is open.

[0041] The fuel cell air system control method disclosed in this invention, since it utilizes the aforementioned fuel cell air system, possesses all the technical effects of the aforementioned fuel cell air system, which will not be elaborated upon here. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 This is a partial system diagram of the fuel cell system disclosed in an embodiment of the present invention;

[0044] Figure 2 This is a schematic diagram of the structure of the fuel cell air system disclosed in an embodiment of the present invention;

[0045] Figure 3 This is an airflow path diagram of the fuel cell air system in the second operating mode as disclosed in an embodiment of the present invention;

[0046] Figure 4 This is an airflow path diagram of the fuel cell air system in the third operating mode disclosed in an embodiment of the present invention;

[0047] Figure 5 This is an airflow path diagram of the fuel cell air system in the first operating mode as disclosed in an embodiment of the present invention.

[0048] The meanings of the various reference numerals in the figure are as follows:

[0049] 101 is an air compressor, 102 is an expander, 103 is an intercooler, 104 is an air combination valve, 105 is a bypass valve, 106 is a water distributor, 107 is a fuel cell stack, 108 is a control system, 109 is a temperature sensor, 110 is a deionizer, 111 is a radiator, 112 is a cooling pump, 113 is a thermostat, 114 is an air intake pipe, 115 is an air exhaust pipe, 116 is a tailpipe pipe, 117 is a drain pipe, and 118 is a back pressure valve. Detailed Implementation

[0050] The core of this invention is to provide a fuel cell air system to ensure that the expander can start up smoothly and operate reliably at low temperatures;

[0051] Another core aspect of this invention is to provide a fuel cell system having the aforementioned fuel cell air system and a fuel cell air system control method.

[0052] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0053] like Figure 1 and Figure 2 As shown, an embodiment of the present invention discloses a fuel cell air system, which includes an air compressor 101, an expander 102, an air intake pipe 114, an air exhaust pipe 115, and a drain pipe 117.

[0054] The air compressor 101 provides the required amount of air to the fuel cell stack 107. Under the action of the air compressor 101, air enters through the inlet of the air compressor 101 and is discharged through the outlet of the air compressor 101, and finally enters the fuel cell stack 107 through the air intake pipe 114.

[0055] Expander 102 is driven by air compressor 101, allowing expander 102 to drive air compressor 101. The air outlet of expander 102 is connected to exhaust pipe 116. Expander 102 can partially recover the energy of the air outlet gas of fuel cell stack 107, thereby reducing the power consumption of system accessories and improving system efficiency.

[0056] One end of the air intake pipe 114 is connected to the outlet of the air compressor 101, and the other end is connected to the air inlet of the fuel cell stack 107. An air combination valve 104 is connected in series on the air intake pipe 114. It should be noted that an intercooler 103 can also be installed upstream of the air combination valve 104 along the air intake direction. The intercooler 103 can exchange heat with the cooling circuit, which is equipped with a deionizer 110, a cooling pump 112, a thermostat 113, and a radiator 111.

[0057] The air inlet and first air outlet of the air combination valve 104 are connected in series to the air intake pipe 114, and the second air outlet of the air combination valve 104 is connected to the air inlet of the expander 102. The opening degree of the first and second air outlets of the air combination valve 104 is adjustable. The air combination valve 104 is a valve with one inlet and two outlets, and the flow rate of the first and second air outlets can be distributed by adjusting the opening degree. That is, the amount of air supplied by the air compressor 101 entering the fuel cell stack 107 and the expander 102 can be distributed through the air combination valve 104.

[0058] One end of the air exhaust pipe 115 is connected to the air outlet of the fuel cell stack 107, and the other end is connected to the air inlet of the expander 102. A water separator 106 and a back pressure valve 118 are connected in series on the air exhaust pipe 115. The water separator 106 can partially separate the liquid water at the air outlet of the fuel cell stack 107, and the separated liquid water can be discharged to the tail drain pipe 116 through the drain pipe 117. When the gas at the air outlet of the fuel cell stack 107 mainly passes through the back pressure valve 118, the air inlet pressure of the fuel cell stack 107 can be adjusted by changing the opening degree of the back pressure valve 118.

[0059] One end of the drain pipe 117 is connected to the drain hole of the water distributor 106, and the other end is connected to the tailpipe 116. A bypass valve 105 is connected in series on the drain pipe 117. When the gas at the air outlet of the fuel cell stack 107 mainly passes through the bypass valve 105, the air inlet pressure of the fuel cell stack 107 can be adjusted by changing the opening degree of the bypass valve 105. The bypass valve 105 also has the function of discharging liquid water inside the water distributor 106.

[0060] The air combination valve 104, back pressure valve 118, and bypass valve 105 can all be dynamically adjustable valves, automatically adjusting their opening values ​​according to relevant parameters after opening. The dynamic adjustment of the back pressure valve 118's opening allows for different opening degrees to adjust the air inlet pressure of the fuel cell stack 107. The dynamic adjustment of the bypass valve 105's opening allows for different opening degrees to adjust the drainage capacity of the water distributor 106; when the back pressure valve 118 is closed, it can also be used to adjust the air inlet pressure of the fuel cell stack 107.

[0061] like Figure 5 As shown, during low-temperature startup of the fuel cell system, both the first and second air outlets of the air combination valve 104 can be opened, the back pressure valve 118 can be closed, and the bypass valve 105 can be opened. Part of the air drawn in by the air compressor 101 flows directly to the air inlet of the expander 102 after passing through the second air outlet of the air combination valve 104. This is used to heat the expander 102. At the same time, the air in the air intake pipe 114 exchanges heat with the cooling circuit through the intercooler 103 and then enters the expander 102 through the air combination valve 104, so that the air in the air intake pipe 114 is heated and can heat the expander 102. This can effectively prevent gas backflow from the air outlet of the expander 102 due to the blockage of the back pressure valve 118, and prevent the expander 102 from absorbing ice particles or hydrogen from the tailpipe 116. A portion of the air drawn in by the air compressor 101 flows to the fuel cell stack 107 through the first air outlet of the air combination valve 104, then flows to the bypass valve 105, and finally, together with the liquid water from the air outlet of the fuel cell stack 107, is discharged to the system's tailpipe 116.

[0062] The valve opening method described above also prevents the liquid water generated on the air side of the fuel cell stack 107 from freezing during the low-temperature start-up process. This is because the fuel cell stack 107 is still at a low temperature. The liquid water flowing to the air outlet of the fuel cell stack 107 may freeze into ice particles as it passes through the system's metal valves / connectors. These ice particles can then enter the expander 102 with the airflow, damaging the expander blades and reducing system reliability. In this embodiment, the back pressure valve 118 cuts off the liquid water discharged from the air outlet of the fuel cell stack 107, allowing it to be directly discharged into the tailpipe 116 through the drain pipe 117. A bypass valve 105 replaces the back pressure valve 118, and the air inlet pressure of the fuel cell stack 107 is adjusted by regulating the opening of the bypass valve 105.

[0063] If the back pressure valve 118 freezes at low temperatures, the valve opening method described above can support normal system operation. During system operation, the high-temperature gas from the air outlet of the fuel cell stack 107 heats the valve plate of the back pressure valve 118, allowing it to thaw quickly and return to normal operation.

[0064] Before the fuel cell system is shut down, the valves described above can be opened so that a portion of the air drawn in by the air compressor 101 flows directly to the air inlet of the expander 102 after passing through the second air outlet of the air combination valve 104. Since the air compressor 101 draws in ambient air, which has a lower humidity than the air outlet of the fuel cell stack 107 and contains no liquid water, this air can be used to directly purge the expander 102 when the system is shut down, removing any liquid water or high-humidity gas inside and preventing freezing due to condensation of liquid or gaseous water at low temperatures.

[0065] This invention can control the different working states of each valve so that the fuel cell air system can work in different modes, meet the working requirements of the fuel cell air system in different working scenarios, and ultimately achieve the goal of enabling the expander 102 to start smoothly and operate reliably at low temperatures.

[0066] like Figure 1As shown, to achieve automatic system adjustment, in this embodiment, the fuel cell air system may further include a control system 108. The fuel cell air system includes a first operating mode. In the first operating mode, the control system 108 controls the first and second air outlets of the air combination valve 104 to be open, the back pressure valve 118 to be closed, and the bypass valve 105 to be open. Specifically, the control system 108 is used to activate the first operating mode when the fuel cell cooling circuit water temperature is lower than a first preset temperature. A temperature sensor 109 is provided on the fuel cell cooling circuit to detect the temperature at the cooling water outlet of the fuel cell stack 107. The fuel cell cooling circuit water temperature can be directly selected from the temperature detected by the temperature sensor 109. When the temperature detected by the temperature sensor 109 is lower than the first preset temperature, the control system 108 activates the first operating mode, thereby avoiding problems caused by low-temperature startup. The control system 108 can activate the first operating mode when the fuel cell cooling circuit water temperature is lower than 0 degrees Celsius. Of course, the first preset temperature can also be other temperatures, which should be set according to actual needs.

[0067] It should be noted that the control system 108 can also activate the first operating mode under other conditions, and is not limited to the condition that the fuel cell cooling circuit water temperature is lower than the first preset temperature. For example, the control system 108 can activate the first operating mode when the room temperature is lower than a certain temperature.

[0068] like Figure 3 As shown, the fuel cell air system may further include a second operating mode. In the second operating mode, the control system 108 controls the first air outlet of the air combination valve 104 to be closed, the second air outlet to be open, the back pressure valve 118 to be closed, and the bypass valve 105 to be closed. The control system 108 may activate the second operating mode when the fuel cell system starts up and / or stops.

[0069] The control system 108 controls the first air outlet, back pressure valve 118, and bypass valve 105 of the air combination valve 104 to be completely closed; then the air drawn in by the air compressor 101 flows directly to the inlet of the expander 102 through the second air outlet of the air combination valve 104, and finally the air flows into the tailpipe 116 of the system through the outlet of the expander 102.

[0070] Select the second working mode during system startup: This can be used to dilute the hydrogen discharged during hydrogen purging at system startup, reduce the hydrogen concentration in tailpipe 116, and meet the system's hydrogen safety requirements.

[0071] Select the second working mode during system shutdown: Since the air compressor 101 draws in ambient air, which has a lower humidity than the air outlet of the fuel cell stack 107 and does not contain liquid water, this air can be used to directly purge the expander 102 during system shutdown, purge the liquid water / high humidity gas inside the expander 102, and prevent the expander 102 from freezing due to the condensation of liquid water or gaseous water at low temperatures.

[0072] In a specific embodiment of the present invention, when the fuel cell system is started and the water temperature in the fuel cell cooling circuit is lower than a first preset temperature, the control system 108 controls the activation of the second operating mode, and after a first preset time, controls the activation of the first operating mode. The fuel cell air system first activates the second operating mode, which can be used to dilute the hydrogen concentration in the tailpipe 116. After the first preset time, when the hydrogen path of the system is replaced, it switches back to the first operating mode to replace the hydrogen in the cavity of the fuel cell stack 107 and to prevent ice particles from the air outlet of the fuel cell stack 107 from entering the expander 102.

[0073] like Figure 4 As shown, the fuel cell air system may also include a third operating mode. In the third operating mode, the control system 108 controls the first air outlet of the air combination valve 104 to be open, the second air outlet to be closed, the back pressure valve 118 to be open, and the bypass valve 105 to be open. In this embodiment, the control system 108 controls the first air outlet of the air combination valve 104 to be fully open, and the back pressure valve 118 and bypass valve 105 to be open, with the opening degree dynamically adjusted. The air drawn in by the air compressor 101 flows through the fuel cell stack 107 and the back pressure valve 118, and then flows to the expander 102. The expander 102 recovers the energy of the air outlet gas of the fuel cell stack 107, reducing the power consumption of the air compressor 101. The purpose of dynamically adjusting the opening of the back pressure valve 118 is to meet the real-time air inlet pressure requirements of the fuel cell stack 107. The purpose of dynamically adjusting the opening of the bypass valve 105 is to meet the drainage requirements of the real-time water distributor 106. However, because it also removes some air flow while draining, reducing the recovery power of the expander 102, the bypass valve 105 needs to be adjusted to a reasonable opening range. The system can operate normally in this third working mode, which is the most common operating state of the system with the expander 102. A large amount of gas from the air outlet of the fuel cell stack 107 passes through the expander 102, which recovers some of the energy from the flowing gas, thereby reducing the power consumption of the air compressor 101 and improving system efficiency.

[0074] When the fuel cell system starts up and the fuel cell cooling circuit water temperature is not lower than the first preset temperature (i.e., room temperature start-up), the control system 108 controls the activation of the second operating mode. After a second preset time, it controls the activation of the third operating mode. The fuel cell air system first activates the second operating mode, which can be used to dilute the hydrogen concentration in the exhaust pipe 116. After the second preset time, when the system's hydrogen path replacement is completed, it switches to the third operating mode, allowing the gas from the air outlet of the fuel cell stack 107 to flow into the expander 102, recovering gas energy, reducing air compressor power consumption, and improving system efficiency. It should be noted that the first and second preset times can be designed to be the same or different depending on the requirements. The specific time should be set according to the application scenario. For example, it can be set according to the time required for the fuel cell system's hydrogen path replacement to ensure that the hydrogen path replacement is completed after the first / second preset time.

[0075] When the fuel cell system starts up and the water temperature in the fuel cell cooling circuit is lower than the first preset temperature, the control system 108 controls the activation of the second operating mode. After a first preset time, it controls the activation of the first operating mode. After meeting preset conditions, it controls the activation of the third operating mode. The fuel cell air system first activates the second operating mode, which can be used to dilute the hydrogen concentration in the tailpipe 116. After the first preset time, when the hydrogen path replacement is completed, it switches back to the first operating mode to replace the hydrogen in the cavity of the fuel cell stack 107 and prevent ice particles from the air outlet of the fuel cell stack 107 from entering the expander 102. After meeting preset conditions, when the air path replacement of the fuel cell air system is completed and it is confirmed that no more ice particles will form at the air outlet of the fuel cell stack 107, the fuel cell air system switches to the third operating mode, allowing the gas from the air outlet of the fuel cell stack 107 to flow into the expander 102, recovering gas energy, reducing air compressor power consumption, and improving system efficiency.

[0076] It should be noted that the preset condition can be: the fuel cell cooling circuit water temperature is higher than a second preset temperature; wherein the second preset temperature is not lower than a first preset temperature. When the fuel cell cooling circuit water temperature is lower than the first preset temperature, there is a risk of icing. When it is higher than the second preset temperature, it indicates that the temperature of the fuel cell stack has increased, thus eliminating the risk of icing. Therefore, no more ice particles will form at the air outlet of the fuel cell stack 107, and the fuel cell air system can switch to the third operating mode. Those skilled in the art will understand that the preset condition can also be set to other conditions, such as time, which can cause the system to automatically switch to the third operating mode after operating in the first operating mode for a period of time.

[0077] In a specific embodiment of the present invention, during the purging of the fuel cell air system, the control system 108 controls the activation of the first working mode, and after a third preset time, controls the activation of the second working mode. The third preset time can be designed to be the same as the first and second preset times, or it can be designed to be different according to requirements. In the first working mode, while purging the fuel cell air system with a large volume of air, a large amount of liquid water between the air outlet of the fuel cell stack 107 and the expander 102 can be blown out. After the third preset time, the purging of the fuel cell air system ends, and then the system switches to the second working mode. The expander 102 is purged with air compressor 101 gas with low relative humidity and no liquid water, ensuring that no liquid water accumulates inside the expander 102 or that high-temperature and high-humidity gas residue condenses into liquid water. This avoids the blades of the expander 102 being corroded by liquid water for a long time (the liquid water at the air outlet of the fuel cell stack 107 is acidic), and prevents the expander 102 from failing to start smoothly due to the freezing of liquid water at low temperatures.

[0078] Before shutting down the system, the fuel cell air system can be purged, especially when the temperature is low and there is a risk of icing.

[0079] In summary, the fuel cell air system disclosed in the embodiments of the present invention has the following technical effects:

[0080] 1) Improve system reliability: By adding a second working mode during the low-temperature purging process, the problem of the expander 102 failing to start at low temperatures due to incomplete purging with liquid or gaseous water can be effectively avoided; by adding a first working mode during the low-temperature start-up process, the ice particles at the air outlet of the fuel cell stack 107 can be effectively prevented from being carried into the expander 102 by the airflow during the low-temperature start-up process, which would damage the blades of the expander 102 and reduce system reliability.

[0081] 2) Improve system functionality and structural integration: In this embodiment of the invention, the bypass valve 105 serves as both a regulator of air flow and pressure and a drain valve on the water distributor 106, simplifying the system's air path structure; when one of the back pressure valve 118 and the bypass valve 105 fails, the two valves have a certain degree of redundancy in function, allowing the system to continue operating using the valve that is still functioning properly.

[0082] 3) Improve system operation safety: By operating in the first working mode, the risk of backflow of hydrogen and ice particles from the tail section when backflow occurs at the outlet of expander 102 can be effectively prevented; by adding the first working mode during system startup, the safety hazards caused by high concentration of hydrogen in the cavity of fuel cell stack 107 flowing into expander 102 during startup can be effectively prevented.

[0083] This invention discloses a fuel cell system, including the fuel cell air system disclosed in the above embodiments, and therefore possesses all the technical effects of the above fuel cell air system, which will not be repeated here.

[0084] This invention also discloses a fuel cell air system control method, which utilizes the fuel cell air system disclosed in the above embodiments, including a low-temperature start-up step, a normal-temperature start-up step, and a purging step.

[0085] The low-temperature start-up step is as follows: when the water temperature in the fuel cell cooling circuit is lower than the first preset temperature, the second working mode is started, and after a first preset time, the first working mode is started; when the water temperature in the fuel cell cooling circuit is higher than the second preset temperature, the third working mode is started, and the second preset temperature is not lower than the first preset temperature.

[0086] The normal temperature start-up procedure is as follows: start the second working mode, and after a second preset time, start the third working mode. The purging procedure is as follows: start the first working mode, and after a third preset time, start the second working mode.

[0087] In the second operating mode, the first air outlet of the air combination valve 104 is closed, the second air outlet is open, the back pressure valve 118 is closed, and the bypass valve 105 is closed. In the first operating mode, both the first and second air outlets of the air combination valve 104 are open, the back pressure valve 118 is closed, and the bypass valve 105 is open. In the third operating mode, the first air outlet of the air combination valve 104 is open, the second air outlet is closed, the back pressure valve 118 is open, and the bypass valve 105 is open. It should be noted that the technical effects of the first, second, and third operating modes can be referred to the fuel cell air system disclosed in the above embodiments, and will not be repeated here.

[0088] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0089] As indicated in this application and claims, unless the context clearly indicates otherwise, the words "a," "an," "a," and / or "the" are not specifically singular and may include the plural. Generally, the terms "comprising" and "including" only indicate the inclusion of expressly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements. An element defined by the phrase "comprising an..." does not exclude the presence of other identical elements in the process, method, product, or apparatus that includes the element.

[0090] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0091] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A fuel cell air system, characterized in that, include: Air compressor (101); An expander (102) is drivenly connected to the air compressor (101), and the air outlet of the expander (102) is connected to the tailpipe (116); An air intake pipe (114) is connected at one end to the outlet of the air compressor (101) and at the other end to the air inlet of the fuel cell stack (107). An air combination valve (104) is connected in series on the air intake pipe (114). The air inlet and the first air outlet of the air combination valve (104) are connected in series on the air intake pipe (114). The second air outlet of the air combination valve (104) is connected to the air inlet of the expander (102). The opening degree of the first air outlet and the second air outlet of the air combination valve (104) is adjustable. An air exhaust pipe (115) is connected at one end to the air outlet of the fuel cell stack (107) and at the other end to the air inlet of the expander (102). A water distributor (106) and a back pressure valve (118) are connected in series on the air exhaust pipe (115). The drain pipe (117) is connected at one end to the drain hole of the water distributor (106) and at the other end to the tail drain pipe (116). A bypass valve (105) is connected in series on the drain pipe (117). The control system (108) includes a first working mode. In the first working mode, the control system (108) controls the first air outlet and the second air outlet of the air combination valve (104) to be in the open state, the back pressure valve (118) to be in the closed state, and the bypass valve (105) to be in the open state.

2. The fuel cell air system according to claim 1, characterized in that, The control system (108) is used to activate the first working mode when the water temperature in the fuel cell cooling circuit is lower than the first preset temperature.

3. The fuel cell air system according to claim 1, characterized in that, The fuel cell air system includes a second operating mode. In the second operating mode, the control system (108) controls the first air outlet of the air combination valve (104) to be closed and the second air outlet to be open, the back pressure valve (118) to be closed and the bypass valve (105) to be closed.

4. The fuel cell air system according to claim 3, characterized in that, When the fuel cell system is started and / or shut down, the control system (108) activates the second operating mode.

5. The fuel cell air system according to claim 3, characterized in that, When the fuel cell system is started and the water temperature in the fuel cell cooling circuit is lower than the first preset temperature, the control system (108) controls the start of the second working mode, and after a first preset time, controls the start of the first working mode.

6. The fuel cell air system according to claim 3, characterized in that, The fuel cell air system includes a third operating mode. In the third operating mode, the control system (108) controls the first air outlet of the air combination valve (104) to be open, the second air outlet to be closed, the back pressure valve (118) to be open, and the bypass valve (105) to be open.

7. The fuel cell air system according to claim 6, characterized in that, When the fuel cell system is started and the water temperature of the fuel cell cooling circuit is not lower than the first preset temperature, the control system (108) controls the start of the second working mode, and after the second preset time, controls the start of the third working mode. When the fuel cell system is started and the water temperature in the fuel cell cooling circuit is lower than the first preset temperature, the control system (108) controls the start of the second working mode, and after a first preset time, controls the start of the first working mode, and after the preset conditions are met, controls the start of the third working mode.

8. The fuel cell air system according to claim 7, characterized in that, The preset conditions for starting the fuel cell system are: the water temperature in the fuel cell cooling circuit is higher than the second preset temperature; wherein the second preset temperature is not lower than the first preset temperature.

9. The fuel cell air system according to claim 6, characterized in that, During the purging of the fuel cell air system, the control system (108) controls the activation of the first working mode, and after a third preset time, controls the activation of the second working mode.

10. The fuel cell air system according to any one of claims 1-9, characterized in that, The air combination valve (104), back pressure valve (118) and bypass valve (105) are all dynamically adjustable valves.

11. A fuel cell system, characterized in that, Includes the fuel cell air system as described in any one of claims 1-10.

12. A control method for a fuel cell air system, characterized in that, The fuel cell air system according to any one of claims 1-10 includes a low-temperature start-up step, a normal-temperature start-up step, and a purging step. The low-temperature start-up step is as follows: when the water temperature in the fuel cell cooling circuit is lower than the first preset temperature, the second working mode is started, and after a first preset time, the first working mode is started; when the water temperature in the fuel cell cooling circuit is higher than the second preset temperature, the third working mode is started, and the second preset temperature is not lower than the first preset temperature. The normal temperature start-up step is as follows: start the second working mode, and after a second preset time, start the third working mode; The purging steps are as follows: start the first working mode, and after a third preset time, start the second working mode; When in the second working mode, the first air outlet of the air combination valve (104) is closed, the second air outlet is open, the back pressure valve (118) is closed, and the bypass valve (105) is closed. When in the first working mode, the first air outlet and the second air outlet of the air combination valve (104) are both open, the back pressure valve (118) is closed, and the bypass valve (105) is open. When in the third working mode, the first air outlet of the air combination valve (104) is in the open state, the second air outlet is in the closed state, the back pressure valve (118) is in the open state, and the bypass valve (105) is in the open state.

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