A multi-condition, low-energy-consumption fuel cell temperature control system and method

Abstract

This invention belongs to the field of fuel cell technology and discloses a multi-condition, low-energy-consumption fuel cell temperature control system and method. The system includes a hydrogen source, an air source, a fuel cell stack, and an exhaust gas treatment module. The hydrogen source and air source are connected to the hydrogen inlet and air inlet of the fuel cell stack, respectively. The exhaust gas treatment module is connected to the outlet of the fuel cell stack. The system also includes a waste heat recovery module, which includes a hydrogen humidification unit, an air humidification unit, a water pump, and a heat exchanger. The fuel cell stack, hydrogen humidification unit, water pump, and heat exchanger are connected sequentially to form a first waste heat recovery loop; the fuel cell stack, air humidification unit, water pump, and heat exchanger are connected sequentially to form a second waste heat recovery loop; and the fuel cell stack, water pump, and heat exchanger are connected sequentially to form a third waste heat recovery loop. This invention solves the problems of high energy consumption and insufficient energy utilization in fuel cell systems.

Description

Technical Field

[0001] This invention belongs to the field of fuel cell technology, and more specifically, relates to a multi-condition, low-energy-consumption fuel cell temperature control system and control method. Background Technology

[0002] Fuel cells are electrochemical power generation devices that directly convert chemical energy into electrical energy. Among them, proton exchange membrane fuel cells (PEMFCs) are the most widely used type in industrial applications. These cells possess outstanding advantages such as high energy conversion efficiency, moderate operating temperature, low operating noise, and clean, pollution-free operation, making them widely applicable in various fields including transportation vehicles, aerospace equipment, stationary energy storage power stations, and underwater propulsion equipment. Their working principle is as follows: hydrogen is introduced at the anode of the fuel cell stack, while air or pure oxygen is introduced at the cathode. Hydrogen undergoes an oxidation reaction in the anode catalyst layer, dissociating into protons and free electrons. Hydrated protons migrate through the proton exchange membrane to the cathode, while electrons are directionally transported to the cathode side via an external circuit. Subsequently, oxygen, under the action of the cathode catalyst, undergoes a reduction reaction with the migrating protons and electrons, ultimately producing liquid water and releasing heat energy. The directional movement of electrons in the external circuit forms a stable current, which can then provide power output to external electrical equipment.

[0003] Currently, proton exchange membrane fuel cells (PEMFCs) suffer from significant energy waste during operation. The stack generates a large amount of waste heat during power generation, which, if dissipated directly, not only reduces energy utilization efficiency but also increases system cooling energy consumption. At the same time, the reaction raw materials, hydrogen and air, need to reach specific humidity and temperature levels to ensure efficient battery operation. Existing systems often use external electrical heating and humidification, further increasing overall energy consumption and resulting in low overall system energy efficiency, which increases the cost of practical applications.

[0004] At present, there are still many problems to be solved in related technologies: First, the waste heat recovery and utilization rate of battery stacks is extremely low. Most of the waste heat is directly discharged through the cooling system and cannot be effectively reused, resulting in energy waste. Second, the heating of raw material gas and humidifying water depends on external auxiliary power supply, which accounts for a high proportion of energy consumption and aggravates the energy loss of the system. Third, the temperature management strategy is not perfect. The temperature control adaptability under various operating conditions such as start-up, operation and shutdown is insufficient, and excessive temperature fluctuations are prone to occur, which not only affect the power generation performance of the battery, but also increase energy consumption and shorten the battery life.

[0005] None of the aforementioned patents related to fuel cell temperature control systems and methods retrieved involve using the heat generated by the fuel cell stack to heat the reaction feedstock hydrogen and air humidification water to improve system energy efficiency, nor do they involve temperature management methods for the system's startup, operation, and shutdown processes. Summary of the Invention

[0006] In view of the above-mentioned defects or improvement needs of the existing technology, the present invention provides a multi-condition low-energy-consumption fuel cell temperature control system and control method, which solves the problems of high energy consumption and insufficient energy utilization of fuel cell control systems.

[0007] To achieve the above objectives, according to one aspect of the present invention, a multi-condition, low-energy-consumption fuel cell temperature control system is provided. This system includes a hydrogen source, an air source, a fuel cell stack, and an exhaust gas treatment module. The hydrogen source and air source are respectively connected to the hydrogen inlet and air inlet of the fuel cell stack. The exhaust gas treatment module is connected to the outlet end of the fuel cell stack. The system further includes a waste heat recovery module, which includes a hydrogen humidification unit, an air humidification unit, a water pump, and a heat exchanger, wherein: The hydrogen humidification unit is located between the hydrogen source and the battery stack. The battery stack, the hydrogen humidification unit, the water pump and the heat exchanger are connected in sequence to form the first waste heat recovery loop. The air humidification unit is located between the air source and the battery stack. The battery stack, the air humidification unit, the water pump and the heat exchanger are connected in sequence to form a second waste heat recovery loop. The battery stack, water pump and heat exchanger are connected in sequence to form a third waste heat recovery loop; The first, second, and third waste heat recovery circuits are equipped with switching valves for switching between the three waste heat recovery circuits.

[0008] More preferably, the system also includes a heater connected to the battery stack for preheating the battery stack.

[0009] More preferably, both the hydrogen humidification unit and the air humidification unit are equipped with a water temperature detector and a liquid level detector.

[0010] More preferably, one end of the hydrogen humidification unit is connected to the hydrogen source, and the other end is connected to the circulating water outlet of the battery stack; one end of the air humidification unit is connected to the air source, and the other end is connected to the circulating water outlet of the battery stack; one end of the water pump is connected to the circulating water outlet of the battery stack, and the other end is connected to the heat exchanger; the heat exchanger is connected to the circulating water inlet of the battery stack.

[0011] More preferably, the switching valve of the first waste heat recovery circuit is located between the circulating water outlet and the hydrogen humidification unit, and between the hydrogen humidification unit and the water pump; the switching valve of the second waste heat recovery circuit is located between the circulating water outlet and the air humidification unit, and between the air humidification unit and the water pump; the switching valve of the third waste heat recovery circuit is located between the circulating water outlet and the water pump.

[0012] More preferably, a flow sensor is provided between the heat exchanger and the battery stack.

[0013] According to another aspect of the present invention, a control method for a multi-condition low-energy-consumption fuel cell temperature control system as described above is provided, the method comprising the following steps: S1 shuts down the first waste heat recovery circuit and the second waste heat recovery circuit, and connects the third waste heat recovery circuit. S2 determines the temperature of the hydrogen humidification unit, the lowest of the temperatures in the air humidification unit and the circulating water inlet. When the temperature of the hydrogen humidification unit is the lowest, the first waste heat recovery circuit is connected, and the second and third waste heat recovery circuits are disconnected; when the temperature of the air humidification unit is the lowest, the second waste heat recovery circuit is connected, and the first and third waste heat recovery circuits are disconnected; when the temperature of the circulating water inlet is the lowest, return to step S1. S3 determines whether the flow rate at the circulating water inlet is within the preset range. If not, return to step S2. If yes, determine whether the temperature at the circulating water inlet is less than the preset threshold. If not, return to step S2. If yes, maintain the current state.

[0014] More preferably, in step S2, in the connection of the first waste heat recovery circuit, the second waste heat recovery circuit or the third waste heat recovery circuit, the flow rate in the circuit is adjusted by adjusting the opening of the regulating valve in each waste heat recovery circuit, so as to maintain the flow rate in the circuit stable.

[0015] More preferably, the control method further includes preheating the battery stack, during which the first waste heat recovery circuit, the second waste heat recovery circuit, and the third waste heat recovery circuit are all disconnected.

[0016] According to another aspect of the invention, a control system is provided, which includes an actuator for performing the control method described above.

[0017] In summary, the technical solutions conceived by this invention have the following beneficial effects compared with the prior art: 1. This invention, through three waste heat recovery loops in the control system and the flexible switching between these loops, precisely controls the operation of the battery to ensure stable and efficient operation while further reducing energy consumption. This provides a practical and feasible technical path for the low-energy-consumption large-scale application of proton exchange membrane fuel cells. The waste heat generated by the battery stack is used to heat the humidifying water for hydrogen and air, replacing or supplementing the auxiliary heating power supply for humidifying water. This avoids the double loss of waste heat and additional heating energy consumption, significantly reducing the overall energy consumption of the system, while improving the energy recycling efficiency and solving the problems of high energy consumption and insufficient energy utilization in existing technologies.

[0018] 2. This invention completes the integrated system design, integrating the three core functions of waste heat recovery, gas humidification and preheating, and temperature control into one, realizing the coordinated linkage of each functional module. This not only simplifies the system structure and reduces equipment complexity, but also reduces energy loss during the connection process between modules, and improves the overall operational stability and reliability of the fuel cell temperature control system.

[0019] 3. This invention has developed a temperature management method adapted to all operating conditions, which can precisely regulate the temperature of fuel cells. This ensures that the fuel cell stack maintains stable and efficient operation under different operating conditions, extends the battery life, and further reduces energy consumption under all operating conditions. This provides practical and feasible technical support for the low-energy large-scale application of proton exchange membrane fuel cells. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a multi-condition, low-energy-consumption fuel cell temperature control system constructed according to a preferred embodiment of the present invention.

[0021] Figure 2 This is a control flowchart of the startup process constructed according to a preferred embodiment of the present invention.

[0022] Figure 3 This is a control flow chart of the operation process constructed according to a preferred embodiment of the present invention.

[0023] Figure 4 This is a shutdown process control flowchart constructed according to a preferred embodiment of the present invention.

[0024] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1-Hydrogen source, 2-Flow controller, 3-Hydrogen humidification unit, 4-Water temperature detector, 5-Liquid level detector, 6-Air source, 7-Air humidification unit, 8-Battery stack, 9-Anode tail gas treatment unit, 10-Cathode tail gas treatment unit, 11-Tail gas emission port, 12-Hydrogen inlet, 13-Air inlet, 14-Circulating water outlet, 15-Circulating water inlet, 16-Flow sensor, 17-First switching valve, 18-First regulating valve, 19-Second switching valve, 20-Second regulating valve, 21-Third switching valve, 22-Three-way valve, 23-Cooling water regulating valve, 25-Heater, 26-Anode outlet, 27-Cathode outlet, 28-Water pump, 29-Heat exchanger. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0026] like Figure 1 The following description uses a fuel cell system as an example. The system includes: a fuel cell stack 8, a hydrogen source 1, an air source 6, and an exhaust gas treatment module.

[0027] The battery stack 8 is equipped with a hydrogen inlet 12, an air inlet 13, a circulating water outlet 14, a circulating water inlet 15, an anode outlet 26, and a cathode outlet 27.

[0028] Hydrogen source 1 is connected to hydrogen inlet 12 of battery stack 8, and a flow controller 2 is installed between them to regulate the flow rate of hydrogen entering the stack; air source 6 is connected to air inlet 13 of battery stack 8, and a flow controller 2 is also installed between them; the other end of battery stack 8 is connected to exhaust gas treatment module, which includes anode exhaust gas treatment unit 9, cathode exhaust gas treatment unit 10 and exhaust gas outlet 11. Anode exhaust gas treatment unit 9 is connected to anode outlet 26, cathode exhaust gas treatment unit 10 is connected to cathode outlet 27, and exhaust gas outlet 11 is connected to the end of both anode exhaust gas treatment unit 9 and cathode exhaust gas treatment unit 10.

[0029] The system also includes a waste heat recovery module, which consists of three waste heat recovery loops: a first waste heat recovery loop, a second waste heat recovery loop, and a third waste heat recovery loop.

[0030] The first waste heat recovery loop includes a battery stack 8, a hydrogen humidification unit 3, a water pump 28, and a heat exchanger 29 connected in sequence. The hydrogen humidification unit 3 is connected to the circulating water outlet 14 of the battery stack 8, and the heat exchanger 29 is connected to the circulating water inlet 15. A first switching valve 17 is provided between the hydrogen humidification unit 3 and the circulating water outlet 14. A first regulating valve 18 is provided between the hydrogen humidification unit 3 and the water pump 28. A three-way valve 22 is provided between the water pump 28 and the heat exchanger 29. A heater 25 is connected in parallel with the heat exchanger 29. One end of the three-way valve 22 is connected to the water pump 28, and the other two ends are connected to the heat exchanger 29 and the heater 25, respectively. One end of the heater 25 is connected to the circulating water inlet 15.

[0031] The second waste heat recovery loop includes a battery stack 8, an air humidification unit 7, a water pump 28 and a heat exchanger 29 connected in sequence. One end of the air humidification unit 7 is connected to the circulating water outlet 14 and the other end is connected to the water pump 28. A second switch valve 19 is provided between the air humidification unit 7 and the circulating water outlet 14, and a fourth opening regulator 20 is provided between the air humidification unit 7 and the water pump 28.

[0032] The third waste heat recovery loop includes a battery stack 8, a water cup, and a heat exchanger 29 connected in sequence. A third switching valve is provided between the circulating water inlet 15 and the water pump 28.

[0033] Both the hydrogen humidification unit 3 and the air humidification unit 7 are equipped with a water temperature detector 4 and a liquid level detector 5.

[0034] The circulating water outlet 14 and circulating water inlet 15 are respectively equipped with a first temperature detector and a second temperature detector. The result detected by the first temperature detector is Ts2, and the result detected by the second temperature detector is Ts1. Both the hydrogen humidification unit 3 and the air humidification unit 7 are equipped with water temperature detection and liquid level detection. The water temperature detected in the hydrogen humidification unit 3 is Ts3, and the liquid level detection result is Ls1. The water temperature detected in the air humidification unit 7 is Ts4, and the liquid level detection result is Ls2. A flow sensor 16 is installed between the heat exchanger 29 and the circulating water inlet 15. The hydrogen humidification module has humidification and heating functions, which can humidify hydrogen to the required humidity and temperature. The air humidification module has humidification and heating functions, which can humidify the air to the required humidity and temperature. The control process of a fuel cell includes the start-up process, the operation process, and the shutdown process, which will be described separately below.

[0035] like Figure 2 As shown, the control process of the startup process is as follows: (1) Adjust the first switch valve 17, the first regulating valve 18, the second switch valve 19 and the second regulating valve 20 on the first waste heat recovery circuit and the second waste heat recovery circuit to the closed state, and adjust the third switch valve 21 on the third waste heat recovery circuit to the open state; (2) Start water pump 28, detect the circulating water inlet flow rate Fs, inlet temperature Ts1, and outlet temperature Ts2 at the reactor inlet 15, and set their corresponding control thresholds Fs11 and Fs2 respectively. Ts11 Ts12 ; (3) Adjust the three-way valve 22 so that the branch where the heat exchanger 29 is located is closed and the branch where the heater 25 is located is open, and perform PID regulation by interlocking the power regulation of the heater 25 with the feedback value of the inlet temperature Ts1. (4) Determine if the feed temperature Ts1 is greater than or equal to the adjustment threshold Ts11 If the temperature management process ends during startup, otherwise return to step (3).

[0036] like Figure 3 As shown, the control process steps of the fuel cell system operation are as follows: (1) Adjust the first switch valve 17, the first regulating valve 18, the second switch valve 19 and the second regulating valve 20 on the first waste heat recovery circuit and the second waste heat recovery circuit to the closed state, and adjust the third switch valve 21 on the third waste heat recovery circuit to the open state; (2) Start water pump 28, and detect the circulating water inlet flow rate Fs, inlet temperature Ts1, outlet temperature Ts2, hydrogen humidification water temperature Ts3, and air humidification water temperature Ts4, and set their corresponding control thresholds Fs21 respectively. Ts21 Ts22 Ts23 Ts24 ; (3) Adjust the three-way valve 22 so that the branch where the heat exchanger 29 is located is open and the branch where the heater 25 is located is closed; (4) Determine whether the temperature of hydrogen humidifying water Ts3 is less than the temperature of air humidifying water Ts4. If Ts3 is less than Ts4, in step S261, determine whether the temperature of hydrogen humidifying water Ts3 is less than the temperature of circulating water exiting the reactor Ts2. If it is less, in step S262, open the first switch valve 17 of the first waste heat recovery circuit and close the third switch valve 21 of the third waste heat recovery circuit. At the same time, the opening of the regulating valve of the first waste heat recovery circuit is linked with the feedback value of the circulating water inlet flow rate for PID regulation to ensure the constant flow rate in the branch. (5) If the judgment is no, then judge whether the air humidification water temperature Ts4 is less than the circulating water outlet temperature Ts2. If the judgment is yes, open the first switch valve 17 of the second waste heat recovery circuit and close the third switch valve 21 of the third waste heat recovery circuit. At the same time, the opening degree of the regulating valve of the first waste heat recovery circuit is linked with the feedback value of the circulating water inlet flow rate for PID regulation. (6) If the judgment is negative, return to (1); determine whether the circulating water flow rate Fs is within the threshold range. If yes, adjust the cooling water regulating valve 23 of heat exchanger 29 to the feed temperature Ts1 feedback value for PID regulation. If no, return to (4). (7) Determine whether Ts1 is less than or equal to the threshold Ts21 If it is the end, return if it is not (4).

[0037] like Figure 4 As shown, the control process for the shutdown of the fuel cell system is as follows: (1) Open the third switch valve 21 of the third waste heat recovery circuit, and close the first switch valve 17, the first regulating valve 18, the second switch valve 19 and the second regulating valve 20 of the first waste heat recovery circuit and the second waste heat recovery circuit, so that the branch of the three-way valve 22 flowing to the heat exchanger 29 is open and the branch of the three-way valve 22 flowing to the heater 25 is closed. (2) The opening degree of the cooling water regulating valve 23 of the heat exchanger 29 is interlocked with the feedback value of the circulating water inlet temperature for PID regulation; (3) Determine whether the circulating water inlet temperature feedback value Ts1 is less than or equal to the set threshold Ts31. If it is the end, return (2) if it is not.

[0038] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A multi-condition, low-energy-consumption fuel cell temperature control system, characterized in that, The system includes a hydrogen source (1), an air source (6), a battery stack (8), and a tail gas treatment module. The hydrogen source (1) and the air source (6) are connected to the hydrogen inlet and air inlet (13) of the battery stack (8), respectively. The tail gas treatment module is connected to the outlet of the battery stack (8). The system also includes a waste heat recovery module, which includes a hydrogen humidification unit (3), an air humidification unit (7), a water pump (28), and a heat exchanger (29), wherein: The hydrogen humidification unit (3) is located between the hydrogen source (1) and the battery stack (8). The battery stack (8), the hydrogen humidification unit (3), the water pump (28) and the heat exchanger (29) are connected in sequence to form the first waste heat recovery loop. The air humidification unit (7) is located between the air source (6) and the battery stack (8). The battery stack (8), the air humidification unit (7), the water pump (28) and the heat exchanger (29) are connected in sequence to form a second waste heat recovery loop. The battery stack (8), water pump (28) and heat exchanger (29) are connected in sequence to form a third waste heat recovery loop; The first, second, and third waste heat recovery circuits are equipped with switching valves for switching between the three waste heat recovery circuits.

2. The multi-condition low-energy-consumption fuel cell temperature control system as described in claim 1, characterized in that, The system is also equipped with a heater (25), which is connected to the battery stack (8) and is used to preheat the battery stack (8).

3. A multi-condition, low-energy-consumption fuel cell temperature control system as described in claim 1 or 2, characterized in that, Both the hydrogen humidification unit (3) and the air humidification unit (7) are equipped with a water temperature detector (4) and a liquid level detector (5).

4. The multi-condition low-energy-consumption fuel cell temperature control system as described in claim 3, characterized in that, One end of the hydrogen humidification unit (3) is connected to the hydrogen source (1), and the other end is connected to the circulating water outlet (14) of the battery stack (8). One end of the air humidification unit (7) is connected to the air source (6), and the other end is connected to the circulating water outlet (14) of the battery stack (8). One end of the water pump (28) is connected to the circulating water outlet (14) of the battery stack (8), and the other end is connected to the heat exchanger (29). The heat exchanger (29) is connected to the circulating water outlet of the battery stack (8).

5. A multi-condition, low-energy-consumption fuel cell temperature control system as described in claim 1 or 4, characterized in that, The switching valve of the first waste heat recovery circuit is located between the circulating water outlet (14) and the hydrogen humidification unit (3), and between the hydrogen humidification unit (3) and the water pump (28); the switching valve of the second waste heat recovery circuit is located between the circulating water outlet (14) and the air humidification unit (7), and between the air humidification unit (7) and the water pump (28); the switching valve of the third waste heat recovery circuit is located between the circulating water outlet (14) and the water pump (28).

6. The multi-condition low-energy-consumption fuel cell temperature control system as described in claim 5, characterized in that, A flow sensor (16) is provided between the heat exchanger (29) and the battery stack (8).

7. A control method for a multi-condition, low-energy-consumption fuel cell temperature control system as described in any one of claims 1-6, characterized in that, The method includes the following steps: S1 shuts down the first waste heat recovery circuit and the second waste heat recovery circuit, and connects the third waste heat recovery circuit. S2 determines the lowest temperature among the hydrogen humidification unit (3), the air humidification unit (7), and the circulating water outlet (14). When the temperature of the hydrogen humidification unit (3) is the lowest, the first waste heat recovery circuit is connected, and the second and third waste heat recovery circuits are disconnected. When the temperature of the air humidification unit (7) is the lowest, the second waste heat recovery circuit is connected, and the first and third waste heat recovery circuits are disconnected. When the temperature of the circulating water outlet (14) is the lowest, return to step S1. S3 determines whether the flow rate at the circulating water inlet (15) is within the preset range. If not, return to step S2. If yes, determine whether the temperature at the circulating water inlet (15) is less than the preset threshold. If not, return to step S2. If yes, maintain the current state.

8. The control method as described in claim 7, characterized in that, In step S2, in the connection of the first waste heat recovery circuit, the second waste heat recovery circuit or the third waste heat recovery circuit, the flow rate in the circuit is adjusted by adjusting the opening of the regulating valve in each waste heat recovery circuit, so as to maintain the flow rate in the circuit stable.

9. The control method as described in claim 7 or 8, characterized in that, The control method also includes preheating the battery stack (8), during which the first waste heat recovery circuit, the second waste heat recovery circuit and the third waste heat recovery circuit are all disconnected.

10. A control system, characterized in that, The system includes an actuator for performing the control method according to any one of claims 7-9.

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