Fuel cell cathode energy recovery system and self-adaptive control method

Abstract

The invention discloses a fuel cell cathode energy recovery system and a self-adaptive control method, which can realize the energy recovery of a fuel cell cathode, consider the design requirement of high integration level, and improve the energy recovery rate of a fuel cell system. And the integration level of the system is greatly improved and the complexity of the system is reduced by controlling the pressure of the fuel cell system through the air inlet three-way valve, the tail discharge water segregator and the adjustable guide vane mechanism. Meanwhile, a feedforward control algorithm based on boundary prediction is adopted, high energy recovery rate can be achieved under different environmental conditions, the environmental adaptability of the fuel cell system is improved, and the application scene is widened.

Description

Technical Field

[0001] The invention relates to a fuel cell cathode energy recovery system and an adaptive control method, belonging to the technical field of fuel cells. Background Art

[0002] Hydrogen energy and fuel cells are important strategic technologies for upgrading the global energy structure and transforming power. Fuel cells have attracted extensive attention as one of the best ways to apply hydrogen energy. Despite its obvious advantages, it still faces challenges such as durability, environmental adaptability and cost to achieve true commercial application.

[0003] The existing fuel cell system includes a fuel cell stack, an air supply system and a hydrogen supply system. Among them, the air compressor is an important component of the air supply system, and its power consumption accounts for a large part of the energy consumption of the entire system. In order to improve the efficiency of the fuel cell system, it is necessary to optimize the energy consumption of the air compressor through the method of fuel cell energy recovery.

[0004] Existing fuel cell energy recovery methods mostly achieve cathode exhaust energy recovery by changing the system architecture. However, most of the existing methods increase the complexity of the system architecture, add different components, increase the difficulty of system layout, are not conducive to improving the high integration of the system, and do not consider its environmental adaptability.

[0005] Therefore, how to improve the existing fuel cell energy recovery technology is a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0006] Purpose: In order to overcome the deficiencies in the prior art, the present invention provides a fuel cell cathode energy recovery system and an adaptive control method, which can improve the efficiency of the fuel cell system, reduce the power consumption of the auxiliary system, and improve the environmental adaptability of the high-power system.

[0007] Technical solution: To solve the above technical problems, the technical solution adopted by the present invention is:

[0008] In the first aspect, a fuel cell cathode energy recovery system comprises: a stack, wherein the cathode inlet end of the stack is connected to the first end of the inlet three-way valve through a pipeline, the second end of the inlet three-way valve is connected to the output end of the intercooler, the input end of the intercooler is connected to the air compressor outlet of the turbine recovery air compressor, the cathode outlet end of the stack is connected to one end of the outlet throttle through a pipeline, the other end of the outlet throttle is connected to the input end of the cathode gas-water separator through a pipeline, the output end of the cathode gas-water separator is connected to the turbine end air inlet of the turbine recovery air compressor, and the air compressor inlet of the turbine recovery air compressor is connected to the output end of the air filter through a pipeline. The turbine end air outlet of the turbine recovery air compressor is connected to the tail gas pipe. The third end of the inlet three-way valve is also connected to the tail gas pipe.

[0009] As a preferred solution, a muffler is provided in the tail pipe.

[0010] As a preferred solution, an integrated environmental temperature and pressure sensor is provided at the air filter input end to measure the temperature and pressure of the environment.

[0011] As a preferred solution, an air flow meter is provided on the pipeline at the air filter output end.

[0012] As a preferred solution, a stack entry temperature sensor and a stack entry pressure sensor are provided on the pipeline at the cathode entry end of the fuel cell stack.

[0013] As a preferred solution, a stack outlet temperature sensor and a stack outlet pressure sensor are provided on the pipeline at the cathode outlet end of the fuel cell stack.

[0014] As a preferred solution, the turbine recovery air compressor adopts a turbine recovery air compressor with an adjustable guide vane mechanism.

[0015] In a second aspect, an adaptive control method for a fuel cell cathode energy recovery system specifically includes:

[0016] Step 1: Collect the current ambient temperature and pressure to determine the current altitude of the fuel cell system.

[0017] Step 2: According to the altitude, obtain the air compressor performance reference value corresponding to the current altitude.

[0018] Step 3: Based on the load current set for the fuel cell system, calculate the air flow required at the stack inlet under current conditions.

[0019] Step 4: According to the required air flow at the fuel cell stack inlet and the reference value of the air compressor performance at the corresponding altitude, adjust the working point of the air compressor and determine whether it meets the requirements of the fuel cell stack. If so, the fuel cell stack will output stably. If not, update the reference value of the air compressor performance at the corresponding altitude and repeat step 4.

[0020] As a preferred solution, the step 2 specifically includes:

[0021] According to the altitude, obtain the reference value of the air flow rate at the air compressor outlet corresponding to the current altitude

[0022] According to the altitude, obtain the reference value ε of the pressure ratio between the inlet and outlet of the air compressor corresponding to the current altitude ref .

[0023] According to the altitude, obtain the air compressor speed reference value n corresponding to the current altitude ref .

[0024] According to the altitude, obtain the ambient temperature reference value T corresponding to the current altitude amb,ref .

[0025] According to the altitude, obtain the ambient pressure reference value p corresponding to the current altitude amb,ref .

[0026] As a preferred solution, the step 3 specifically includes:

[0027] According to the load current set by the fuel cell system, the air flow m required at the inlet of the stack under the current conditions is calculated. The air flow m required at the inlet of the stack under the current conditions is calculated by the following formula:

[0028] m=I×λ c ×n st ×3.5773×10 -7

[0029] Where, I is the load current, in A; λ c is the excess air coefficient; n st is the number of fuel cell stack cells.

[0030] As a preferred solution, the step 4 specifically includes:

[0031] Step 4.1: According to the current ambient temperature T amb , the ambient temperature reference value T corresponding to the current altitude amb,ref And the air compressor speed reference value n corresponding to the current altitude ref , calculate the air compressor speed n under the current environment, the calculation formula is as follows:

[0032]

[0033] Step 4.2: According to the current ambient temperature T amb , the ambient temperature reference value T corresponding to the current altitude amb,ref , current environmental pressure p amb, the ambient pressure reference value p corresponding to the current altitude amb,ref And the reference value of the air compressor outlet air flow corresponding to the current altitude Calculate the air flow rate at the compressor outlet under the current environment The calculation formula is as follows:

[0034]

[0035] Step 4.3: According to the air compressor speed n and the air compressor outlet air flow rate in the current environment Adjust the operating point of the air compressor.

[0036] Step 4.4: Determine the air flow rate at the compressor outlet under the current environment Check whether the air flow m required at the stack inlet under the current conditions is met, or whether the stack inlet pressure under the current environment meets the stack inlet pressure reference value p' under the current conditions. If all of the above conditions are met, the stack outputs stably. If any of the above conditions is not met, update the air compressor performance reference value at the corresponding altitude and return to step 4.1.

[0037] As a preferred solution, the calculation formula of the reference value p' of the stack inlet pressure under the current conditions is as follows:

[0038] p'=min(p ca,in,ref ,ε max p amb )

[0039] Among them, min() means taking the minimum value, p ca,in,ref Cathode reference pressure, ε max is the maximum pressure ratio of the air compressor, p am The current environmental pressure.

[0040] As a preferred solution, the maximum pressure ratio of the air compressor ε max , the calculation formula is as follows:

[0041]

[0042] Among them, m1 and m2 are the fitting parameters of the air compressor surge line, x0 is the threshold, n1, n2 and n3 are the fitting parameters corresponding to the maximum combined speed curve of the air compressor,

[0043] As a preferred solution, the step 4 further includes:

[0044] If the current environment is the air compressor outlet air flow If it is not within the boundary threshold range, the reference value of the air compressor performance at the corresponding altitude is updated and the process returns to step 4.1.

[0045] The boundary threshold intervals are as follows:

[0046]

[0047] in, The air compressor outlet flow rate corresponding to the minimum combined speed on the general surge line; It is the flow rate in the blocked area of ​​the air compressor.

[0048] Beneficial effects: The fuel cell cathode energy recovery system and adaptive control method provided by the present invention can realize the energy recovery of the fuel cell cathode while considering its high integration design requirements. While improving the energy recovery rate of the fuel cell system, the system integration is greatly improved and the complexity of the system is reduced by controlling the pressure of the fuel cell system through the intake three-way valve, the tail water distributor and the use of an adjustable guide vane mechanism. At the same time, the present invention adopts a feedforward control algorithm based on boundary prediction, which can have a high energy recovery rate under different environmental conditions, improve the environmental adaptability of the fuel cell system, and broaden the application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 Schematic diagram of the fuel cell cathode energy recovery system architecture.

[0050] Figure 2 Schematic diagram of the flow of the adaptive control method for the fuel cell cathode energy recovery system. DETAILED DESCRIPTION

[0051] The following is a clear and complete description of the technical solutions in the examples of the present invention in conjunction with the accompanying drawings in the examples of the present invention. Obviously, the described embodiments are only 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 those skilled in the art without creative work are within the protection scope of the present invention.

[0052] The present invention will be further described below in conjunction with specific embodiments.

[0053] Embodiment 1:

[0054] This embodiment introduces a fuel cell cathode energy recovery system. Figure 1As shown, it includes: a stack 1, wherein the cathode inlet end 101 of the stack 1 is connected to the first end of the inlet three-way valve 2 through a pipeline, the second end of the inlet three-way valve 2 is connected to the output end of the intercooler 3, the input end of the intercooler 3 is connected to the air compressor outlet 401 of the turbine recovery air compressor 4, the cathode outlet end 102 of the stack 1 is connected to one end of the outlet throttle 5 through a pipeline, the other end of the outlet throttle 5 is connected to the input end of the cathode gas-water separator 6 through a pipeline, the output end of the cathode gas-water separator 6 is connected to the turbine end air inlet 403 of the turbine recovery air compressor 4, and the air compressor inlet 402 of the turbine recovery air compressor 4 is connected to the output end of the air filter 7 through a pipeline. The turbine end air outlet 404 of the turbine recovery air compressor 4 is connected to the tail gas pipe. The third end of the inlet three-way valve 2 is also connected to the tail gas pipe.

[0055] Furthermore, a muffler 8 is provided in the tail pipe.

[0056] Furthermore, an environmental temperature and pressure integrated sensor 9 is provided at the input end of the air filter 7 for measuring the temperature and pressure of the environment.

[0057] Furthermore, an air flow meter 10 is provided on the pipeline at the output end of the air filter 7 .

[0058] Furthermore, a stack entry temperature sensor 11 and a stack entry pressure sensor 12 are provided on the pipeline of the cathode stack entry end 101 of the fuel cell stack 1 .

[0059] Furthermore, a stack outlet temperature sensor 13 and a stack outlet pressure sensor 14 are provided on the pipeline of the cathode stack outlet end 102 of the fuel cell stack 1 .

[0060] Furthermore, the turbine recovery air compressor 4 is a turbine recovery air compressor with an adjustable guide vane mechanism.

[0061] Embodiment 2:

[0062] This embodiment introduces the working principle of a fuel cell cathode energy recovery system. When the system is running, the stack temperature sensor 13 and the stack pressure sensor 14 are used to detect whether the temperature and pressure of the stack air meet the system usage requirements; the stack throttle 5 is used to seal the stack outlet to prevent external exhaust gas from entering the stack during shutdown. Compared with the traditional fuel cell cathode system architecture, this system architecture adds a cathode gas-water separator 6 after the stack throttle 5, thereby increasing the service life of the air compressor turbine end impeller and avoiding liquid water entering the turbine end to cause corrosion to the impeller. After passing through the turbine end of the air compressor, the exhaust gas provides energy to the compression end of the air compressor, reducing the power consumption of the air compressor and realizing the cathode energy recovery of the system. After that, it passes through the tail exhaust silencer and is discharged into the atmosphere.

[0063] Fresh air from the outside passes through the air filter 7 and the air flow meter 10 and then enters the compression end of the air compressor, where it works together with the turbine end to pass the compressed gas into the intercooler 3; air that meets the temperature requirements of the fuel cell stack is passed into the fuel cell stack 1 through the intercooler 3; the integrated ambient temperature and pressure sensor 9 is used to detect the temperature and pressure of the current atmospheric environment as one of the judgment bases for the adaptive control method.

[0064] The three-way air inlet valve 2 at the rear end of the intercooler 3 replaces the two inlet throttle valves of the traditional architecture, and is used to control the air flow rate of the system inlet and the flow rate ratio of the bypass into the exhaust gas, which greatly improves the system integration and saves the system cost. The inlet temperature sensor 11 and the inlet pressure sensor 12 are used to detect whether the temperature and pressure of the air entering the fuel cell 1 meet the use requirements of the fuel cell, which is an important basis for judging whether the working point of the air compressor is adjusted.

[0065] In addition, compared with the traditional fuel cell system architecture, this architecture uses an adjustable guide vane structure turbine recovery air compressor, eliminating the system's back pressure valve. Only the air compressor needs to be controlled to achieve the flow and pressure control of the air path, which improves the system's integration and reduces the difficulty of system control.

[0066] Embodiment 3:

[0067] This embodiment introduces an adaptive control method for a fuel cell cathode energy recovery system. The method adjusts the air compressor operating parameters based on the real-time collected ambient temperature and pressure signals, improves the environmental adaptability of the fuel cell system at different altitudes, and enables the fuel cell system to have a higher energy recovery efficiency in different environments. Figure 2 As shown, specifically including:

[0068] Step 1: Collect the current ambient temperature and pressure to determine the current altitude of the fuel cell system.

[0069] Step 2: According to the altitude, obtain the air compressor performance reference value corresponding to the current altitude.

[0070] Step 3: Based on the load current set for the fuel cell system, calculate the air flow required at the stack inlet under current conditions.

[0071] Step 4: According to the required air flow at the fuel cell stack inlet and the reference value of the air compressor performance at the corresponding altitude, adjust the working point of the air compressor and determine whether it meets the requirements of the fuel cell stack. If so, the fuel cell stack will output stably. If not, update the reference value of the air compressor performance at the corresponding altitude and repeat step 4.

[0072] Furthermore, the step 2 specifically includes:

[0073] According to the altitude, obtain the reference value of the air flow rate at the air compressor outlet corresponding to the current altitude

[0074] According to the altitude, obtain the reference value ε of the pressure ratio between the inlet and outlet of the air compressor corresponding to the current altitude ref .

[0075] According to the altitude, obtain the air compressor speed reference value n corresponding to the current altitude ref .

[0076] According to the altitude, obtain the ambient temperature reference value T corresponding to the current altitude amb,ref .

[0077] According to the altitude, obtain the ambient pressure reference value p corresponding to the current altitude amb,rrf .

[0078] Furthermore, the step 3 specifically includes:

[0079] According to the load current set by the fuel cell system, the air flow m required at the inlet of the stack under the current conditions is calculated. The air flow m required at the inlet of the stack under the current conditions is calculated by the following formula:

[0080] m=I×λ c ×n st ×3.5773×10 -7

[0081] Where, I is the load current, in A; λ c is the excess air coefficient; n st is the number of fuel cell stack cells.

[0082] Furthermore, the step 4 specifically includes:

[0083] Step 4.1: According to the current ambient temperature T amb , the ambient temperature reference value T corresponding to the current altitude amb,ref And the air compressor speed reference value n corresponding to the current altitude ref , calculate the air compressor speed n under the current environment, the calculation formula is as follows:

[0084]

[0085] Step 4.2: According to the current ambient temperature T amb , the ambient temperature reference value T corresponding to the current altitude amb,ref , current environmental pressure p amb , the ambient pressure reference value p corresponding to the current altitude amb,ref And the reference value of the air compressor outlet air flow corresponding to the current altitude Calculate the air flow rate at the compressor outlet under the current environment The calculation formula is as follows:

[0086]

[0087] Step 4.3: According to the air compressor speed n and the air compressor outlet air flow rate in the current environment Adjust the operating point of the air compressor.

[0088] Step 4.4: Determine the air flow rate at the compressor outlet under the current environment Check whether the air flow m required at the stack inlet under the current conditions is met, or whether the stack inlet pressure under the current environment meets the stack inlet pressure reference value p' under the current conditions. If all of the above conditions are met, the stack outputs stably. If any of the above conditions is not met, update the air compressor performance reference value at the corresponding altitude and return to step 4.1.

[0089] Furthermore, the calculation formula of the reference value p' of the stack inlet pressure under the current conditions is as follows:

[0090] p'=min(p ca,in,ref ,ε max p amb )

[0091] Among them, min() means taking the minimum value, p ca,in,ref Cathode reference pressure, ε max is the maximum pressure ratio of the air compressor, p am The current environmental pressure.

[0092] Furthermore, the maximum pressure ratio of the air compressor ε max , the calculation formula is as follows:

[0093]

[0094] Among them, m1 and m2 are the fitting parameters of the air compressor surge line, x0 is the threshold, n1, n2 and n3 are the fitting parameters corresponding to the maximum combined speed curve of the air compressor,

[0095] Furthermore, the step 4 further includes:

[0096] If the current environment is the air compressor outlet air flow If it is not within the boundary threshold range, the reference value of the air compressor performance at the corresponding altitude is updated and the process returns to step 4.1.

[0097] The boundary threshold intervals are as follows:

[0098]

[0099] in, The air compressor outlet flow rate corresponding to the minimum combined speed on the general surge line; It is the flow rate in the blocked area of ​​the air compressor.

[0100] The adaptive control method of the present invention can greatly improve the environmental adaptability of the fuel cell system, and the only actuator that needs to be controlled by the cathode system is the air compressor (the speed of the air compressor and the position of its guide vane mechanism are controlled to adjust the air flow and pressure), thereby improving the system's integration.

[0101] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A fuel cell cathode energy recovery system, comprising: A fuel cell stack, characterized in that: the cathode inlet end of the fuel cell stack is connected to the first end of the inlet three-way valve through a pipeline, the second end of the inlet three-way valve is connected to the output end of the intercooler, the input end of the intercooler is connected to the air compressor outlet of the turbine recovery air compressor, the cathode outlet end of the fuel cell stack is connected to one end of the outlet throttle through a pipeline, the other end of the outlet throttle is connected to the input end of the cathode gas-water separator through a pipeline, the output end of the cathode gas-water separator is connected to the turbine end air inlet of the turbine recovery air compressor, the air compressor inlet of the turbine recovery air compressor is connected to the output end of the air filter through a pipeline; the turbine end air outlet of the turbine recovery air compressor is connected to the tail pipe; the third end of the inlet three-way valve is also connected to the tail pipe.

2. A fuel cell cathode energy recovery system according to claim 1, characterized in that: A muffler is arranged in the tail gas pipe; an integrated ambient temperature and pressure sensor is arranged at the air filter input end for measuring the ambient temperature and pressure; an air flow meter is arranged on the pipeline at the air filter output end; an inlet temperature sensor and an inlet pressure sensor are arranged on the pipeline at the cathode inlet end of the fuel cell stack; and an outlet temperature sensor and an outlet pressure sensor are arranged on the pipeline at the cathode outlet end of the fuel cell stack.

3. A fuel cell cathode energy recovery system according to claim 1, characterized in that: The turbine recovery air compressor adopts a turbine recovery air compressor with an adjustable guide vane mechanism.

4. An adaptive control method for a fuel cell cathode energy recovery system, characterized in that: Specifically include: Step 1: Collect the current ambient temperature and pressure to determine the current altitude of the fuel cell system; Step 2: According to the altitude, obtain the air compressor performance reference value corresponding to the current altitude; Step 3: Calculate the air flow required at the stack inlet under current conditions based on the load current set by the fuel cell system; Step 4: According to the required air flow at the fuel cell stack inlet and the reference value of the air compressor performance at the corresponding altitude, adjust the working point of the air compressor and determine whether it meets the requirements of the fuel cell stack. If so, the fuel cell stack will output stably. If not, update the reference value of the air compressor performance at the corresponding altitude and repeat step 4.

5. The adaptive control method according to claim 4, characterized in that: The step 2 specifically includes: According to the altitude, obtain the reference value of the air flow rate at the air compressor outlet corresponding to the current altitude According to the altitude, obtain the reference value ε of the pressure ratio between the inlet and outlet of the air compressor corresponding to the current altitude ref ; According to the altitude, obtain the air compressor speed reference value n corresponding to the current altitude ref ; According to the altitude, obtain the ambient temperature reference value T corresponding to the current altitude amb,ref ; According to the altitude, obtain the ambient pressure reference value P corresponding to the current altitude amb,ref .

6. The adaptive control method according to claim 4, characterized in that: The step 3 specifically includes: According to the load current set by the fuel cell system, calculate the air flow m required at the inlet of the fuel cell stack under the current conditions; The air flow m required for the stack inlet under the current conditions is calculated as follows: m=I×λ c ×n st ×3.5773×10 -7 Where, I is the load current, in A; λ c is the excess air coefficient; n st is the number of fuel cell stack cells.

7. The adaptive control method according to claim 4, characterized in that: The step 4 specifically includes: Step 4.1: According to the current ambient temperature T amb , the ambient temperature reference value T corresponding to the current altitude amb，ref And the air compressor speed reference value n corresponding to the current altitude ref , calculate the air compressor speed n under the current environment, the calculation formula is as follows: Step 4.2: According to the current ambient temperature T amb , the ambient temperature reference value T corresponding to the current altitude amb,ref , current environmental pressure P amb , the ambient pressure reference value P corresponding to the current altitude amb,ref And the reference value of the air compressor outlet air flow corresponding to the current altitude Calculate the air flow rate at the compressor outlet under the current environment The calculation formula is as follows: Step 4.3: According to the air compressor speed n and the air compressor outlet air flow rate in the current environment Adjust the working point of the air compressor; Step 4.4: Determine the air flow rate at the compressor outlet under the current environment Check whether the air flow m required at the stack inlet under the current conditions is met, or whether the stack inlet pressure under the current environment meets the stack inlet pressure reference value p′ under the current conditions. If all of the above conditions are met, the stack outputs stably. If any of the above conditions is not met, update the air compressor performance reference value at the corresponding altitude and return to step 4.

1.

8. The adaptive control method according to claim 7, characterized in that: The calculation formula of the reference value p' of the stack inlet pressure under the current conditions is as follows: p'=min(p ca,in，ref ,he max p amb ); Among them, min() means taking the minimum value, p ca,in,ref Cathode reference pressure, ε max is the maximum pressure ratio of the air compressor, p amb The current environmental pressure.

9. The adaptive control method according to claim 8, characterized in that: Maximum pressure ratio of air compressor ε max , the calculation formula is as follows: Among them, m1 and m2 are the fitting parameters of the air compressor surge line, x0 is the threshold, n1, n2 and n3 are the fitting parameters corresponding to the maximum combined speed curve of the air compressor, 10. The adaptive control method according to claim 7, characterized in that: The step 4 further includes: If the current environment is the air compressor outlet air flow If it is not within the boundary threshold range, update the reference value of the air compressor performance at the corresponding altitude and return to step 4.1; The boundary threshold intervals are as follows: in, The air compressor outlet flow rate corresponding to the minimum combined speed on the general surge line; It is the flow rate in the blocked area of ​​the air compressor.

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