A high-temperature proton exchange membrane fuel cell (PEMFC) temperature control device and a temperature control method

Abstract

The application discloses a high-temperature proton exchange membrane fuel cell (PEMFC) temperature control device and a temperature control method, and belongs to the technical field of fuel cell testing. The device comprises a first-stage heat-conducting oil preheating circulation system, a second-stage heat-conducting oil operation circulation system and a secondary water cooling system which are sequentially connected through pipelines; the first-stage heat-conducting oil preheating circulation system exchanges heat with the second-stage heat-conducting oil operation circulation system, and provides a preheating heat source for the second-stage heat-conducting oil operation circulation system; the second-stage heat-conducting oil operation circulation system is directly connected with a high-temperature PEMFC stack, and is used for controlling the temperature of the stack; and the secondary water cooling system exchanges heat with the second-stage heat-conducting oil operation circulation system, and is used for regulating and controlling the heat dissipation of the stack in an operation stage. The application aims to solve the core problems in the prior art, such as the fact that a water cooling medium cannot be adapted to a 120-200 DEG C high-temperature working condition, the fact that the single-stage heat exchange has insufficient heat dissipation capacity, the fact that the temperature fluctuates greatly, the fact that the heat-conducting oil is easy to coking and blockage when directly heated, and the fact that preheating and operation are not controlled in stages.

Description

Technical Field

[0001] This invention belongs to the field of fuel cell testing technology, and particularly relates to a temperature control device and method for a high-temperature proton exchange membrane fuel cell (PEMFC). Background Technology

[0002] High-temperature proton exchange membrane fuel cells (PEMFCs) can operate at temperatures ranging from 120 to 200°C. They possess advantages such as high catalyst activity, strong fuel flexibility, and good impurity tolerance, making them an important direction for the development of fuel cell technology. During high-temperature PEMFC testing, precise and stable control of the stack temperature directly affects the reliability and consistency of the test data.

[0003] Existing conventional fuel cell temperature control devices mostly use deionized water as the heat exchange medium, which can only meet the temperature control requirements of low-temperature PEMFCs (60-90℃) and cannot adapt to high-temperature conditions (120-200℃). Furthermore, existing high-temperature test benches mostly adopt a single-stage heat exchange structure with heat transfer oil, which has three major drawbacks: First, direct heating by a single-stage electric heater easily leads to localized overheating and coking of the heat transfer oil, clogging the coolant channels of the fuel cell stack; second, single-stage heat exchange lacks temperature buffering, resulting in large temperature fluctuations and insufficient temperature control accuracy under varying operating conditions of high-power fuel cell stacks; third, preheating and operation are not controlled in stages, resulting in slow cold start-up, continuous operation of the heating device during normal operation leading to energy waste, and low system integration, which is not conducive to the standardization and modular deployment of the test bench.

[0004] In view of the above-mentioned defects in existing high-temperature fuel cell temperature control technology, the purpose of this invention is to provide a high-temperature proton exchange membrane fuel cell (PEMFC) temperature control device and method, aiming to solve the core problems in the existing technology, such as the inability of water-cooled media to adapt to high-temperature conditions of 120-200℃, insufficient heat dissipation capacity of single-stage heat exchange, large temperature fluctuations, easy coking and blockage of heat transfer oil when directly heated, and lack of graded control for preheating and operation. Summary of the Invention

[0005] This invention provides a temperature control device and method for high-temperature proton exchange membrane fuel cells (PEMFCs) to overcome the above-mentioned problems.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: This invention provides a temperature control device for a high-temperature proton exchange membrane fuel cell (PEMFC), comprising a primary heat transfer oil preheating circulation system, a secondary heat transfer oil operating circulation system, and a secondary water cooling system connected in sequence via pipelines; The primary heat transfer oil preheating circulation system exchanges heat with the secondary heat transfer oil operating circulation system, providing a preheating heat source for the secondary heat transfer oil operating circulation system; The secondary heat transfer oil circulation system is directly connected to the high-temperature PEMFC fuel cell stack to control the stack temperature. The primary heat transfer oil preheating circulation system and the secondary heat transfer oil operating circulation system are two independent closed-loop circulation loops with the heat transfer oil medium not connected to each other. The secondary water cooling system exchanges heat with the secondary heat transfer oil circulation system to achieve temperature control of the high-temperature PEMFC stack within a wide temperature range of 120-200℃.

[0007] Furthermore, the primary heat transfer oil preheating circulation system includes a first expansion tank, a first circulation pump, a coolant heat exchanger, and an electric heater; The oil outlet of the first expansion tank is connected to the inlet of the first circulation pump, the outlet of the first circulation pump is connected to the primary side of the coolant heat exchanger and the electric heater, and the outlet pipeline of the electric heater is connected to the first expansion tank, forming a primary closed circulation loop.

[0008] Furthermore, the secondary heat transfer oil operating circulation system includes a second expansion tank, a second circulation pump, a fuel cell stack temperature control plate heat exchanger, and a high-temperature PEMFC fuel cell stack; The oil outlet of the second expansion tank is connected to the inlet of the second circulation pump, the outlet of the second circulation pump is connected in sequence to the primary side of the fuel cell stack temperature control plate heat exchanger, the outlet pipe of the fuel cell stack temperature control plate heat exchanger is connected to the inlet of the high-temperature PEMFC fuel cell stack coolant, and the outlet of the high-temperature PEMFC fuel cell stack coolant is connected to the secondary side of the coolant heat exchanger and then flows back to the second expansion tank, forming a two-stage closed circulation loop.

[0009] Furthermore, the secondary water cooling system includes a secondary water inlet, a secondary water regulating valve, and a secondary water outlet; The secondary water inlet is connected to the secondary side inlet of the fuel cell stack temperature control plate heat exchanger, and the secondary side outlet of the fuel cell stack temperature control plate heat exchanger is connected in sequence to the secondary water regulating valve and the secondary water outlet, forming an open cooling water circuit.

[0010] Furthermore, the high-temperature proton exchange membrane fuel cell (PEMFC) temperature control device also includes a test bench frame, on which the primary heat transfer oil preheating circulation system, the secondary heat transfer oil operation circulation system, and the secondary water cooling system are all fixedly installed.

[0011] Furthermore, the test bench frame is equipped with casters or leveling feet at the bottom.

[0012] Furthermore, the first expansion tank is provided with a first oil injection valve at the top, a first liquid level sensor at the side of the first expansion tank, and a first drain valve at the bottom of the first expansion tank; The outlet of the first circulating pump is connected to the second pressure sensor; the outlet pipeline of the electric heater is equipped with a second temperature sensor and a first pressure relief valve; the electric heater is equipped with a fourth temperature sensor.

[0013] Furthermore, the second expansion tank is provided with a second oil injection valve at the top, a second liquid level sensor at the side of the second expansion tank, and a second drain valve at the bottom of the second expansion tank; The outlet of the second circulating pump is connected in sequence to the third pressure sensor and the liquid flow meter. The outlet pipeline of the heat exchanger of the stack temperature control plate is equipped with a second pressure relief valve. The inlet of the high-temperature PEMFC stack is equipped with a fourth pressure sensor and a third temperature sensor. The outlet of the high-temperature PEMFC stack coolant is connected in sequence to the first temperature sensor and the first pressure sensor.

[0014] Another aspect of the present invention provides a temperature control method using the aforementioned high-temperature proton exchange membrane fuel cell (PEMFC) temperature control device, comprising the following steps: S1: Open the first oil injection valve to add high-temperature resistant first-level heat transfer oil into the first expansion tank, monitor the liquid level through the first liquid level sensor, and close the first oil injection valve after the set liquid level is reached; simultaneously open the second oil injection valve to add high-temperature resistant second-level heat transfer oil into the second expansion tank, monitor the liquid level through the second liquid level sensor, and close the second oil injection valve after the set liquid level is reached. Start the first circulation pump and run it at low speed until the liquid level in the first expansion tank is stable and there are no obvious air bubbles. Then, increase the first circulation pump to its rated speed. Simultaneously start the second circulation pump and run it until the liquid level in the second expansion tank is stable and there are no obvious air bubbles. Then, increase the second circulation pump to its rated speed. S2: The primary heat transfer oil flowing out of the first expansion tank is pressurized by the first circulation pump and measured by the second pressure sensor. It then enters the primary side of the coolant heat exchanger, exchanges heat with the heat transfer oil on the secondary side, and flows out into the electric heater to be heated. The electric heater heats the primary heat transfer oil to the set preheating temperature. The heated primary heat transfer oil then flows back to the first expansion tank through the first pressure relief valve, completing the primary cycle. The secondary heat transfer oil flowing out of the second expansion tank is pressurized by the second circulation pump, measured by the third pressure sensor, and metered by the liquid flow meter before entering the primary side of the heat exchanger of the stack temperature control plate. Then it enters the high-temperature PEMFC stack coolant channel through the second pressure relief valve to transfer heat to the stack body. The secondary heat transfer oil flows out from the fuel cell stack outlet, and after being monitored by the first temperature sensor and the first pressure sensor, it enters the secondary side of the coolant heat exchanger, absorbs the heat transferred by the primary heat transfer oil, and then flows back to the second expansion tank to complete the secondary cycle. S3: Open the secondary water regulating valve. Secondary cooling water enters the secondary side of the fuel cell stack temperature control plate heat exchanger from the secondary water inlet. It exchanges heat with the secondary heat transfer oil on the primary side and absorbs the waste heat of the fuel cell stack carried by the secondary heat transfer oil. After heat exchange, the secondary water is discharged from the secondary water outlet after the flow rate is regulated by the secondary water regulating valve. S4: The second circulation pump continues to run, and the secondary water regulating valve remains fully open; the fuel cell outlet temperature is monitored by the first temperature sensor until the temperature drops below 80°C. Close the secondary water regulating valve to stop the secondary water supply; then gradually reduce the speed of the second circulation pump until it stops running; simultaneously stop the first circulation pump.

[0015] The beneficial effects of this invention are: (1) Abandoning the single-stage heat exchange mode, a two-stage circulation system is set up with the primary heat transfer oil preheating cycle and the secondary heat transfer oil operating cycle being independent of each other. The two-stage circulation achieves indirect heat transfer through the coolant heat exchanger. The primary circulation is equipped with an electric heater as a heat source, and the secondary circulation is directly connected to the fuel cell stack coolant channel. The two-stage circulation is independently controlled and works in coordination. This avoids the problem of local overheating and coking of the heat transfer oil caused by the electric heater directly heating the secondary heat transfer oil, prevents the fuel cell coolant channel from being blocked or narrowed, and extends the service life of the system; the two-stage heat exchange forms a temperature buffer, greatly reduces temperature fluctuations, improves temperature control accuracy, and ensures the consistency of test data; the two-stage circulation operates independently and can flexibly switch the operating mode according to the working conditions to adapt to the needs of different stages such as preheating, operation, and heat preservation.

[0016] (2) The structure is compact, highly integrated, and occupies a small area, making it easy to arrange and relocate the test bench; the modular design facilitates the maintenance and replacement of each component, reducing maintenance costs; the pipeline layout is standardized, the fluid resistance is small, the heat exchange efficiency is high, and the system operation is more stable.

[0017] (3) Rapid heating during cold start-up shortens test preparation time and improves test efficiency; electric heater stops working during normal operation to avoid energy waste and reduce operating costs; bidirectional temperature control capability allows for both heating and cooling, adapting to stable temperature control under varying operating conditions of the fuel cell stack.

[0018] (4) The heat transfer oil medium is resistant to high temperature, does not vaporize or condense, solves the problem that water-cooled medium cannot be used when it vaporizes above 100℃, and meets the requirements of high temperature PEMFC testing; the closed-loop oil circuit operates stably, with low medium loss, long maintenance cycle and low operating cost; the heat transfer oil has stable heat exchange performance, smooth temperature control, no vaporization impact, and improves the safety and stability of the testing process.

[0019] (5) Configure a pressure relief valve to realize automatic pressure relief for overpressure, configure a temperature sensor to realize multi-point temperature monitoring and over-temperature protection, configure a pressure sensor to realize full pipeline pressure monitoring, configure a liquid level sensor to realize expansion tank liquid level monitoring, and connect the signals of each sensor to the control system to realize closed-loop protection. Attached Figure Description

[0020] 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the internal connections of the temperature control device described in this invention; Figure 2 This is a three-dimensional layout diagram of the temperature control device described in this invention; In the diagram: 1-High-temperature PEMFC stack; 2-First pressure sensor; 3-First temperature sensor; 4-Electric heater; 5-Second temperature sensor; 6-First expansion tank; 7-First oil injection valve; 8-First liquid level sensor; 9-Second pressure sensor; 10-First circulating pump; 11-First drain valve; 12-Second oil injection valve; 13-Second liquid level sensor; 14-Second drain valve; 15-Second circulating pump; 16-Liquid flow meter; 17-Third pressure sensor; 18-Coolant heat exchanger; 19-Stack temperature control plate heat exchanger; 20-Fourth pressure sensor; 21-Third temperature sensor; 22-Secondary water inlet; 23-Secondary water regulating valve; 24-Secondary water outlet; 25-First pressure relief valve; 26-Second pressure relief valve; 27-Fourth temperature sensor; 28-Secondary expansion tank; 29-First-stage heat transfer oil preheating circulation system; 30-Secondary-stage heat transfer oil operating circulation system; 31-Secondary water cooling system. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, 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.

[0023] This embodiment provides a temperature control device and method for a high-temperature proton exchange membrane fuel cell (PEMFC). The high-temperature proton exchange membrane fuel cell (PEMFC) temperature control device includes a primary heat transfer oil preheating circulation system 29, a secondary heat transfer oil running circulation system 30, and a secondary water cooling system 31 connected in sequence by pipelines. The primary heat transfer oil preheating circulation system 29 exchanges heat with the secondary heat transfer oil operating circulation system 30, providing a preheating heat source for the secondary heat transfer oil operating circulation system 30; The secondary heat transfer oil circulation system 30 is directly connected to the high-temperature PEMFC stack 1 to achieve stack temperature control. The secondary water cooling system 31 exchanges heat with the secondary heat transfer oil circulation system 30 to regulate the heat dissipation of the fuel cell stack during operation.

[0024] This device uses a two-stage heat transfer oil circulation system as its core, employing heat transfer oil as the high-temperature heat exchange medium. It utilizes a staged control strategy of primary circulation preheating and secondary circulation operation to achieve precise temperature control of the high-temperature PEMFC stack across a wide temperature range of 120-200℃. The primary circulation uses electric heater 4 as the heat source, transferring heat to the secondary circulation heat transfer oil through coolant heat exchanger 18, enabling rapid temperature rise during the cold start phase of the stack. The secondary circulation is directly connected to the stack coolant channel, and during normal operation, it exchanges heat with secondary water through the stack temperature control plate heat exchanger 19 to remove the heat generated by the stack's power generation, maintaining a stable stack operating temperature.

[0025] Furthermore, the primary heat transfer oil preheating circulation system 29 includes a first expansion tank 6, a first circulation pump 10, a coolant heat exchanger 18, and an electric heater 4; The oil outlet of the first expansion tank 6 is connected to the inlet of the first circulation pump 10, and the outlet of the first circulation pump 10 is connected to the primary side of the coolant heat exchanger 18 and the electric heater 4. The outlet pipeline of the electric heater 4 is connected to the first expansion tank 6, forming a primary closed circulation loop.

[0026] The primary heat transfer oil preheating circulation system 29 is used during the system's cold start phase. It heats the primary heat transfer oil via an electric heater, and indirectly preheats the secondary heat transfer oil via a coolant heat exchanger, avoiding localized overheating and coking problems caused by the electric heater directly heating the secondary heat transfer oil. The primary circulation operates independently. After preheating is completed, the electric heater stops working, and the primary circulation enters standby or low-speed circulation mode.

[0027] Furthermore, the secondary heat transfer oil circulation system 30 includes a second expansion tank 28, a second circulation pump 15, a fuel cell stack temperature control plate heat exchanger 19, and a high-temperature PEMFC fuel cell stack 1; The oil outlet of the second expansion tank 28 is connected to the inlet of the second circulation pump 15. The outlet of the second circulation pump 15 is connected in sequence to the primary side of the fuel cell stack temperature control plate heat exchanger 19. The outlet pipe of the fuel cell stack temperature control plate heat exchanger 19 is connected to the coolant inlet of the high-temperature PEMFC fuel cell stack 1. The coolant outlet of the high-temperature PEMFC fuel cell stack 1 is connected to the secondary side of the coolant heat exchanger 18 and then flows back to the second expansion tank 28, forming a two-stage closed circulation loop.

[0028] The secondary heat transfer oil circulation system 30 is the core loop for temperature control, directly exchanging heat with the high-temperature PEMFC stack 1. During the cold start phase, the secondary heat transfer oil absorbs the heat transferred from the primary circulation, gradually preheating the stack to its operating temperature. During normal power generation operation, the heat generated by the stack is carried out by the secondary heat transfer oil, cooled by heat exchange with secondary water in the stack temperature control plate heat exchanger, and then flows back to the expansion tank, achieving stable control of the stack temperature.

[0029] Furthermore, the secondary water cooling system 31 includes a secondary water inlet 22, a secondary water regulating valve 23, and a secondary water outlet 24; The secondary water inlet 22 is connected to the secondary side inlet of the fuel cell stack temperature control plate heat exchanger 19, and the secondary side outlet of the fuel cell stack temperature control plate heat exchanger 19 is connected in sequence to the secondary water regulating valve 23 and the secondary water outlet 24, forming an open cooling water circuit.

[0030] The secondary water cooling system 31 is the main heat dissipation path during normal operation. It utilizes secondary water and secondary heat transfer oil to exchange heat in the heat exchanger 19 of the fuel cell stack temperature control plate, thus removing the waste heat generated by the fuel cell stack. The cooling water flow rate is precisely adjusted by the secondary water regulating valve 23, and with the closed-loop feedback of the temperature sensor, high-precision control of the fuel cell stack temperature is achieved.

[0031] Furthermore, the high-temperature proton exchange membrane fuel cell (PEMFC) temperature control device also includes a test bench frame, on which the primary heat transfer oil preheating circulation system 29, the secondary heat transfer oil running circulation system 30, and the secondary water cooling system 31 are all fixedly installed.

[0032] This system achieves physical partitioning and functional coordination of primary preheating and secondary operation cycles within the same rack. The rack is divided into four functional areas: the preheating heating area houses the first expansion tank 6, the first circulation pump 10, the electric heater 4, and valve assemblies, forming an independent preheating heat source module; the operation heat exchange area houses the second expansion tank 28, the second circulation pump 15, the fuel cell stack temperature control plate heat exchanger 19, the coolant heat exchanger 18, and secondary water valve assemblies, forming the core operation heat exchange module; the fuel cell stack interface area reserves standardized interfaces and monitoring instruments to achieve rapid fuel cell stack docking; and the auxiliary equipment area houses electrical control and safety protection components. The four functional areas are connected by internal piping within the rack. Heat from the preheating zone is transferred to the secondary heat transfer oil via a coolant heat exchanger. Physical isolation and thermal coupling prevent coking of the heat transfer oil caused by direct heating from the electric heater. Phased control is optimized under the integrated layout: during the cold start phase, the preheating zone operates at full power, indirectly heating the secondary heat transfer oil to steadily raise the temperature of the fuel cell stack; during normal operation, the preheating zone operates at low power consumption in standby mode, while the operating zone precisely regulates heat dissipation through a secondary water regulating valve to maintain a stable fuel cell stack temperature.

[0033] Furthermore, the test bench frame is equipped with casters or leveling feet at the bottom, which facilitates the overall layout and relocation of the test bench; the modular design facilitates the maintenance and replacement of each component, reducing maintenance costs; the pipeline layout is standardized, with low fluid resistance, high heat exchange efficiency, and more stable system operation.

[0034] Furthermore, the first expansion tank 6 is provided with a first oil injection valve 7 at the top for adding heat transfer oil, a first liquid level sensor 8 on the side of the first expansion tank 6 for monitoring the liquid level inside the tank, and a first drain valve 11 at the bottom of the first expansion tank 6 for discharging heat transfer oil. The outlet of the first circulating pump 10 is connected to the second pressure sensor 9; the outlet pipeline of the electric heater 4 is equipped with a second temperature sensor 5 and a first pressure relief valve 25; the electric heater 4 is equipped with a fourth temperature sensor 27.

[0035] Furthermore, the second expansion tank 28 is provided with a second oil injection valve 12 at the top for adding heat transfer oil, a second liquid level sensor 13 on the side of the second expansion tank 28 for monitoring the liquid level inside the tank, and a second drain valve 14 at the bottom of the second expansion tank 28 for discharging heat transfer oil. The outlet of the second circulating pump 15 is connected in sequence to the third pressure sensor 17 and the liquid flow meter 16. The outlet pipeline of the heat exchanger 19 of the fuel cell stack temperature control plate is equipped with a second pressure relief valve 26. The inlet of the high-temperature PEMFC fuel cell stack is equipped with a fourth pressure sensor 20 and a third temperature sensor 21. The outlet of the coolant of the high-temperature PEMFC fuel cell stack 1 is connected in sequence to the first temperature sensor 3 and the first pressure sensor 2.

[0036] The pressure relief valves and sensors mentioned above together constitute a multi-layered safety protection system. Pressure relief valves enable automatic pressure relief in case of overpressure; temperature sensors enable multi-point temperature monitoring and over-temperature protection; pressure sensors enable full pipeline pressure monitoring; and level sensors enable expansion tank level monitoring. The signals from each sensor are integrated into the control system to achieve closed-loop protection, ensuring safe operation under high temperature and high pressure conditions and reducing the risk of accidents. Real-time monitoring of all process parameters facilitates fault diagnosis and operational status assessment. Automatic alarms and protection against abnormal conditions such as over-temperature, over-pressure, and low liquid level enhance system reliability.

[0037] The operation of this device is divided into four stages: system oil injection and venting stage, cold start preheating stage, normal steady-state operation stage, and system shutdown and cooling stage. The specific operating steps for each stage are as follows: S1, System oil filling and venting stage When using for the first time or restarting after a long period of inactivity, perform an oil filling and venting operation. Open the first oil filling valve 7 to add high-temperature resistant heat transfer oil into the first expansion tank 6, monitor the liquid level through the first liquid level sensor 8, and close the first oil filling valve 7 after the set liquid level is reached; simultaneously open the second oil filling valve 12 to add high-temperature resistant heat transfer oil into the second expansion tank 28, monitor the liquid level through the second liquid level sensor 13, and close the second oil filling valve 12 after the set liquid level is reached.

[0038] Start the first circulation pump 10 at low speed to drive the heat transfer oil in the primary pipeline to circulate and expel air from the pipeline. After the liquid level in the first expansion tank 6 is stable and there are no obvious air bubbles, increase the first circulation pump 10 to the rated speed. Simultaneously start the second circulation pump 15 at low speed to drive the heat transfer oil in the secondary pipeline to circulate and expel air from the pipeline. After the liquid level in the second expansion tank 28 is stable and there are no obvious air bubbles, increase the second circulation pump 15 to the rated speed.

[0039] Check the readings of each pressure sensor, temperature sensor, and level sensor to ensure they are normal, confirm that there are no leaks in any pipelines, and complete the preparation work for system oil filling and venting.

[0040] S2, Cold Start Preheating Stage After confirming that the piping connection of the high-temperature PEMFC stack 1 is completed, the cold start preheating program is started. The first circulation pump 10 is started, and the primary heat transfer oil flows out from the first expansion tank 6. After being pressurized by the first circulation pump 10 and measured by the second pressure sensor 9, it enters the primary side of the coolant heat exchanger 18, exchanges heat with the heat transfer oil on the secondary side, and then flows out into the electric heater 4 for heating.

[0041] The electric heater 4 is powered on and heats the primary heat transfer oil to the set preheating temperature. The second temperature sensor 5 monitors the oil temperature in real time after heating, and the fourth temperature sensor 27 monitors the surface temperature of the electric heater as an over-temperature protection device. The heated primary heat transfer oil flows back to the first expansion tank 6 through the first pressure relief valve 25, completing the primary cycle.

[0042] The second circulation pump 15 is started simultaneously. Secondary heat transfer oil flows out from the second expansion tank 28, is pressurized by the second circulation pump 15, measured by the third pressure sensor 17, and metered by the liquid flow meter 16. It then enters the primary side of the heat exchanger 19 of the fuel cell stack temperature control plate (at this time, the secondary water regulating valve is closed). Subsequently, it enters the high-temperature PEMFC fuel cell stack 1 coolant channel through the second pressure relief valve 26, transferring heat to the fuel cell stack body.

[0043] The secondary heat transfer oil flows out from the fuel cell stack outlet, and after being monitored by the first temperature sensor 3 and the first pressure sensor 2, it enters the secondary side of the coolant heat exchanger 18, absorbs the heat transferred by the primary heat transfer oil, and then flows back to the second expansion tank 28 to complete the secondary cycle.

[0044] During the preheating process, the fuel cell stack temperature is monitored in real time by the third temperature sensor 21 at the inlet and the first temperature sensor 3 at the outlet. The primary cycle heating temperature is gradually increased until the fuel cell stack temperature reaches the set operating temperature (a target value within the range of 120-200℃). After the set temperature is reached, the electric heater 4 stops heating, and the primary cycle enters a low-speed heat preservation or standby state, thus ending the preheating stage.

[0045] S3, Normal steady-state operation phase The high-temperature PEMFC stack 1 begins normal power generation operation. The electrochemical reaction inside the stack generates a large amount of heat, at which point it enters the normal steady-state temperature control stage. The second circulation pump 15 continues to operate, and the secondary heat transfer oil continuously carries away the heat generated by the stack.

[0046] When the secondary water regulating valve 23 is opened, the secondary cooling water enters the secondary side of the fuel cell stack temperature control plate heat exchanger 19 from the secondary water inlet 22, and exchanges heat with the high-temperature heat transfer oil on the primary side, absorbing the waste heat of the fuel cell stack carried by the heat transfer oil. After heat exchange, the secondary water is discharged from the secondary water outlet 24 after the flow rate is regulated by the secondary water regulating valve 23.

[0047] Temperature feedback from the first temperature sensor 3 at the fuel cell stack outlet is used to adjust the opening of the secondary water regulating valve 23 in a closed loop, controlling the secondary water flow rate and thus regulating the heat exchange capacity of the fuel cell stack temperature control plate heat exchanger 19, maintaining the fuel cell stack inlet and outlet temperatures stable at the set values. The liquid flow meter 16 monitors the secondary heat transfer oil flow rate in real time to ensure sufficient heat exchange medium flow.

[0048] During normal operation, the electric heater 4 of the primary circulation system remains stopped, while the first circulation pump 10 can operate at low speed or stop as needed. When fluctuations in the fuel cell load cause a temperature drop that cannot be maintained by secondary water regulation alone, the electric heater 4 can be briefly activated to supplement heat, achieving bidirectional precise temperature control.

[0049] During operation, pressure and temperature sensors collect operating parameters in real time, level sensors monitor the liquid level in the expansion tank, and the first pressure relief valve 25 and the second pressure relief valve 26 automatically open to relieve pressure when the system is overpressured, together ensuring the stable and safe operation of the system.

[0050] S4, System shutdown and cooling phase After the high-temperature PEMFC stack 1 stops generating electricity, it enters the shutdown and cooling phase. First, the electric heater 4 is turned off to ensure that the heating system completely stops working.

[0051] The second circulation pump 15 continues to operate, and the secondary water regulating valve 23 remains fully open. The secondary water continuously removes heat from the secondary heat transfer oil, causing the fuel cell stack temperature to gradually decrease. The fuel cell stack outlet temperature is monitored by the first temperature sensor 3 until the temperature drops to a safe range (usually below 80°C).

[0052] After the fuel cell stack temperature drops to a safe range, close the secondary water regulating valve 23 to stop the secondary water supply. Then gradually reduce the speed of the second circulation pump 15 until it stops operating. Simultaneously stop the first circulation pump 10.

[0053] Check the readings of all pressure sensors to confirm that there is no residual pressure in the system, confirm that the readings of all temperature sensors are within the safe temperature range, and confirm that the readings of the liquid level sensor are normal. Turn off all instruments and control equipment to complete the shutdown of the entire unit. If a long-term shutdown is required, the heat transfer oil in the system can be drained through the first drain valve 11 and the second drain valve 14.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A temperature control device for a high-temperature proton exchange membrane fuel cell (PEMFC), characterized in that, It includes a primary heat transfer oil preheating circulation system (29), a secondary heat transfer oil operating circulation system (30), and a secondary water cooling system (31) connected in sequence by pipelines. The primary heat transfer oil preheating circulation system (29) exchanges heat with the secondary heat transfer oil operating circulation system (30) to provide a preheating heat source for the secondary heat transfer oil operating circulation system (30); The secondary heat transfer oil circulation system (30) is directly connected to the high-temperature PEMFC stack (1) to achieve stack temperature control. The primary heat transfer oil preheating circulation system (29) and the secondary heat transfer oil operation circulation system (30) are two independent closed-loop circulation loops with the heat transfer oil medium not connected to each other. The secondary water cooling system (31) exchanges heat with the secondary heat transfer oil circulation system (30) to achieve temperature control of the high-temperature PEMFC stack (1) in a wide temperature range of 120-200℃.

2. The temperature control device for a high-temperature proton exchange membrane fuel cell (PEMFC) according to claim 1, characterized in that, The primary heat transfer oil preheating circulation system (29) includes a first expansion tank (6), a first circulation pump (10), a coolant heat exchanger (18), and an electric heater (4). The oil outlet of the first expansion tank (6) is connected to the inlet of the first circulation pump (10), and the outlet of the first circulation pump (10) is sequentially connected to the primary side of the coolant heat exchanger (18) and the electric heater (4). The outlet pipeline of the electric heater (4) is connected to the first expansion tank (6) to form a first-level closed circulation loop.

3. The temperature control device for a high-temperature proton exchange membrane fuel cell (PEMFC) according to claim 1, characterized in that, The secondary heat transfer oil circulation system (30) includes a second expansion tank (28), a second circulation pump (15), a fuel cell stack temperature control plate heat exchanger (19), and a high-temperature PEMFC fuel cell stack (1). The oil outlet of the second expansion tank (28) is connected to the inlet of the second circulation pump (15), the outlet of the second circulation pump (15) is connected to the primary side of the fuel cell stack temperature control plate heat exchanger (19), the outlet pipeline of the fuel cell stack temperature control plate heat exchanger (19) is connected to the coolant inlet of the high-temperature PEMFC fuel cell stack (1), and the coolant outlet of the high-temperature PEMFC fuel cell stack (1) is connected to the secondary side of the coolant heat exchanger (18) and then flows back to the second expansion tank (28), forming a two-stage closed circulation loop.

4. The temperature control device for a high-temperature proton exchange membrane fuel cell (PEMFC) according to claim 3, characterized in that, The secondary water cooling system (31) includes a secondary water inlet (22), a secondary water regulating valve (23), and a secondary water outlet (24). The secondary water inlet (22) is connected to the secondary side inlet of the electric stack temperature control plate heat exchanger (19), and the secondary side outlet of the electric stack temperature control plate heat exchanger (19) is connected to the secondary water regulating valve (23) and the secondary water outlet (24) in sequence, forming an open cooling water circuit.

5. The temperature control device for a high-temperature proton exchange membrane fuel cell (PEMFC) according to claim 1, characterized in that, It also includes a test bench frame, on which the primary heat transfer oil preheating circulation system (29), the secondary heat transfer oil operation circulation system (30), and the secondary water cooling system (31) are all fixedly installed.

6. The temperature control device for a high-temperature proton exchange membrane fuel cell (PEMFC) according to claim 5, characterized in that, The test bench frame is equipped with casters or leveling feet at the bottom.

7. The temperature control device for a high-temperature proton exchange membrane fuel cell (PEMFC) according to claim 2, characterized in that, The first expansion tank (6) is provided with a first oil injection valve (7) at the top, a first liquid level sensor (8) is provided on the side of the first expansion tank (6), and a first drain valve (11) is provided at the bottom of the first expansion tank (6). The outlet of the first circulating pump (10) is connected to the second pressure sensor (9); the outlet pipeline of the electric heater (4) is equipped with a second temperature sensor (5) and a first pressure relief valve (25); the electric heater (4) is equipped with a fourth temperature sensor (27).

8. The temperature control device for a high-temperature proton exchange membrane fuel cell (PEMFC) according to claim 3, characterized in that, The second expansion tank (28) is provided with a second oil injection valve (12) at the top, a second liquid level sensor (13) is provided on the side of the second expansion tank (28), and a second drain valve (14) is provided at the bottom of the second expansion tank (28). The outlet of the second circulating pump (15) is connected in sequence to the third pressure sensor (17) and the liquid flow meter (16). The outlet pipeline of the heat exchanger (19) of the electric stack is equipped with a second pressure relief valve (26). The inlet of the high-temperature PEMFC electric stack (1) is equipped with a fourth pressure sensor (20) and a third temperature sensor (21). The outlet of the coolant of the high-temperature PEMFC electric stack (1) is connected in sequence to the first temperature sensor (3) and the first pressure sensor (2).

9. A temperature control method using the high-temperature proton exchange membrane fuel cell (PEMFC) temperature control device according to any one of claims 1-8, characterized in that, Includes the following steps: S1: Open the first oil injection valve (7) to add high-temperature resistant first-level heat transfer oil into the first expansion tank (6), monitor the liquid level through the first liquid level sensor (8), and close the first oil injection valve (7) after adding to the set liquid level; simultaneously open the second oil injection valve (12) to add high-temperature resistant second-level heat transfer oil into the second expansion tank (28), monitor the liquid level through the second liquid level sensor (13), and close the second oil injection valve (12) after adding to the set liquid level. Start the first circulation pump (10) and run it at low speed until the liquid level in the first expansion tank (6) is stable and there are no obvious bubbles. Then increase the first circulation pump (10) to the rated speed. Simultaneously start the second circulation pump (15) and run it until the liquid level in the second expansion tank (28) is stable and there are no obvious bubbles. Then increase the second circulation pump (15) to the rated speed. S2: The primary heat transfer oil flowing out from the first expansion tank (6) is pressurized by the first circulation pump (10) and measured by the second pressure sensor (9). It then enters the primary side of the coolant heat exchanger (18), exchanges heat with the heat transfer oil on the secondary side, and flows out into the electric heater (4) to heat up. The electric heater (4) heats the primary heat transfer oil to the set preheating temperature. The heated primary heat transfer oil flows back to the first expansion tank (6) through the first pressure relief valve (25) to complete the primary cycle. The secondary heat transfer oil flowing out from the second expansion tank (28) is pressurized by the second circulation pump (15), measured by the third pressure sensor (17), and metered by the liquid flow meter (16). It then enters the primary side of the heat exchanger (19) of the stack temperature control plate and then enters the coolant channel of the high-temperature PEMFC stack (1) through the second pressure relief valve (26) to transfer heat to the stack body. The secondary heat transfer oil flows out from the fuel cell outlet, and after being monitored by the first temperature sensor (3) and the first pressure sensor (2), it enters the secondary side of the coolant heat exchanger (18), absorbs the heat transferred by the primary heat transfer oil, and then flows back to the second expansion tank (28) to complete the secondary cycle. S3: Open the secondary water regulating valve (23), and the secondary cooling water enters the secondary side of the heat exchanger (19) of the electric stack temperature control plate from the secondary water inlet (22), and exchanges heat with the secondary heat transfer oil on the primary side, absorbing the waste heat of the electric stack carried by the secondary heat transfer oil. After heat exchange, the secondary water is discharged from the secondary water outlet (24) after the flow rate is regulated by the secondary water regulating valve (23). S4: The second circulation pump (15) continues to run, and the secondary water regulating valve (23) remains fully open; the fuel cell outlet temperature is monitored by the first temperature sensor (3) until the temperature drops below 80°C; Close the secondary water regulating valve (23) to stop the secondary water supply; then gradually reduce the speed of the second circulation pump (15) until the second circulation pump (15) stops running; simultaneously stop the first circulation pump (10) running.

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