A low-power air-cooled fuel cell rapid low-power-consumption low-temperature cold start system and control method

Abstract

This invention discloses a rapid, low-energy-consumption, low-temperature cold start system and control method for a low-power air-cooled fuel cell, belonging to the field of fuel cell low-temperature cold start technology. It includes a low-temperature start-up preheater, a cathode gas heat recovery pipeline, an electric butterfly valve-type rotary baffle, a temperature sensor, and multiple valves. While ensuring the recovery and reuse of waste heat through a sealed connection between the cathode gas heat recovery pipeline and the stack outlet and inlet, the system is intelligently heated by the low-temperature start-up preheater placed in the circulating preheating cold start channel. Rapid on / off control of the cathode gas heat recovery pipeline enables rapid switching of the preheating pipeline. Waste heat recovery technology, intelligent heating strategies, and adaptive control strategies based on multi-parameter feedback reduce preheating energy consumption. Intelligent control methods enable rapid, low-energy cold start-up of the fuel cell in environments at 0℃ and below, along with integrated shutdown and purging protection. This improves battery life, efficiency, and low-temperature adaptability.

Description

Technical Field

[0001] This invention relates to the field of PEMFC technology, specifically to a fast, low-power consumption, low-temperature cold start system and control method for a low-power air-cooled fuel cell. Background Technology

[0002] Air-cooled PEMFCs have broad application prospects in portable power supplies, drones, and small vehicles due to their advantages such as simple structure, small size, and low cost. However, in low-temperature environments (especially at zero degrees Celsius and below), ice formation is prone to occur inside the fuel cell. Ice crystals can block the pores and channels of the gas diffusion layer, severely hindering the transport of reactant gases and the discharge of products, leading to a sharp decline in battery performance, difficulty in starting up, and even irreversible mechanical damage to the membrane electrode assembly (MEA) caused by the stress generated by ice crystal growth.

[0003] Currently, several technical solutions have been proposed to address the issue of low-temperature start-up in fuel cells. Common solutions include utilizing the reaction heat of the fuel cell stack itself, preheating the intake air with an external heater, adding low-temperature start-up aids, or employing complex liquid thermal management systems. For example, some solutions attempt to directly heat the cathode inlet air, but this method is energy-intensive and economically unfeasible for low-power systems. Other solutions attempt to recover heat by guiding the high-temperature exhaust gas from the cathode outlet back to the inlet, but in the initial stage of ultra-low temperature start-up, the fuel cell stack itself generates insufficient heat, resulting in limited heat recovery and failing to meet the demand for rapid temperature rise. Still other solutions use a catalytic burner to burn residual hydrogen for heat generation, but the system is complex, posing control difficulties and safety risks. For low-power air-cooled PEMFCs, designing a low-temperature cold start-up system that is fast-responding, low-energy, highly reliable, and has low fuel cell stack energy consumption within a limited budget for volume, weight, and energy consumption remains a current technological challenge.

[0004] Therefore, there is an urgent need in this field for a simple, reliable, flexible, compact, and adaptable low-power air-cooled fuel cell cryogenic cold start system and intelligent control strategy, so as to achieve both protection of the fuel cell stack and reliable rapid start-up from a shutdown state in harsh low-temperature environments. Summary of the Invention

[0005] The main objective of this invention is to provide a fast, low-power, low-temperature cold start system and control method for a low-power air-cooled fuel cell, in order to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides a low-power, air-cooled fuel cell rapid low-power cold start system, comprising: The fuel cell stack assembly includes a fuel cell stack body and a cathode gas heat recovery pipe located between the outlet and inlet of the fuel cell stack body. A cathode fan is installed on the cathode side of the fuel cell stack body within the cathode gas heat recovery pipe. A hydrogen inlet pipe is connected to the anode flow channel inlet of the fuel cell stack body, and a hydrogen outlet pipe is connected to the anode flow channel outlet of the fuel cell stack body. An auxiliary fan is installed within the cathode gas heat recovery pipe, and an electrically operated butterfly valve-type rotary baffle is provided on the cathode gas heat recovery pipe. The end of the hydrogen inlet pipe furthest from the fuel cell stack body is connected to a hydrogen source and sequentially fitted with a manual shut-off valve and a pressure reducing valve. A first pressure sensor is provided between the manual shut-off valve and the pressure reducing valve. A second pressure sensor is provided on the hydrogen outlet pipe. A low-temperature start-up preheater includes a cathode recovery gas heating section and a hydrogen pipeline heating section, respectively; the hydrogen inlet pipe is located inside the cathode gas heat recovery pipe and inside the hydrogen pipeline heating section. The intelligent control component includes a PCB board electrically connected to the low-temperature start-up preheating component; a solenoid valve is provided between the PCB board and the hydrogen outlet pipe; the electric butterfly valve rotary baffle, the first pressure sensor, the second pressure sensor, the cathode fan, and the solenoid valve are respectively electrically connected to the PCB board; a first temperature sensor, a second temperature sensor, a third temperature sensor, a fourth temperature sensor, and a fifth temperature sensor, which are electrically connected to the PCB board, are respectively provided in the cathode gas heat recovery pipe, on the hydrogen inlet pipe, on the anode side of the fuel cell stack, on the hydrogen pipeline heating section, and on the cathode recovery gas heating section.

[0007] As a further improvement of the present invention, the inner wall of the cathode gas heat recovery pipe is provided with an inner wall thermally conductive coating.

[0008] As a further improvement of the present invention, the outer wall of the cathode gas heat recovery pipe is provided with an outer wall insulation material made of ceramic fiber or polyurethane foam.

[0009] As a further improvement of the present invention, the electric butterfly valve type rotary baffle is installed at the bypass or switching node of the cathode gas heat recovery pipeline, and the opening and closing of the cathode gas heat recovery pipeline is realized by rotation, which is used to regulate the on and off of the waste heat recovery circuit.

[0010] As a further improvement of the present invention, both the cathode recovery gas heating section and the hydrogen pipeline heating section adopt resistance wire heating, and the heating power of the resistance wire heating is independently adjustable, with power ranges of 0.5~2.0 kW and 0.2~1.0 kW, respectively.

[0011] As a further improvement of the present invention, the steady-state operating temperature of the cathode gas recovery heating section is set to 90℃±3℃; the upper limit of the heating temperature of the hydrogen pipeline heating section is 40℃.

[0012] As a further improvement of the present invention, it also includes a DC power supply; a circuit breaker is connected in series in the power supply circuit between the DC power supply and the low-temperature start-up preheater; a first single-control switch and a second single-control switch are respectively connected between the DC power supply and the cathode gas recovery heating section and between the hydrogen pipeline heating section; a voltage relay is electrically connected between the DC power supply and the PCB board.

[0013] A cold start control method for a low-power, air-cooled fuel cell rapid low-power cold start system, executed by a PCB board, includes the following steps: Step 1: Temperature Monitoring and Mode Determination When the system is powered on and initialized, the PCB board directly connected to the host computer collects the ambient temperature T of the first temperature sensor, the hydrogen inlet temperature T1 of the second temperature sensor, the fuel cell body temperature T2 of the third temperature sensor, the hydrogen heating temperature T3 of the fourth temperature sensor, and the cathode gas heating temperature T4 of the fifth temperature sensor in real time. Based on the ambient temperature T, select and enter the corresponding cold start sub-mode: preheating protection mode, low-power preheating start mode, or normal start mode. If the ambient temperature T < 2℃, the preheating protection mode is entered: the electric butterfly valve type rotary baffle is in the initial state to close the cathode gas heat recovery pipeline and isolate it from the external environment. The cathode recovery gas heating part and hydrogen pipeline heating part of the low temperature start-up preheater are started to preheat the recovery gas and hydrogen. The start of the fuel cell stack body is prohibited until the temperature of the fuel cell stack body detected by the third temperature sensor rises to above 2℃. If 2℃ ≤ ambient temperature T < 10℃, enter the low-power preheating start-up mode: control the electric butterfly valve to rotate 45°, the electric butterfly valve to open halfway, so that the cathode heat recovery pipeline is connected to the external environment, start the cathode recovery gas heating section, and preheat the cathode intake gas; control the fuel cell stack to start and run at low power. If the ambient temperature T ≥ 10℃, enter the normal start-up mode: control the electric butterfly valve to rotate 90°, close the low temperature start-up preheater, and after the electric butterfly valve rotates, close the upper part of the cathode heat recovery pipe, connect the fuel cell stack body to the external environment, and the fuel cell stack body starts normally. Step 2: Multi-mode coordinated heating and flow control In the preheating protection mode and low-power preheating start-up mode, the heating temperature and heating time of the cathode recovery gas heating section and the hydrogen pipeline heating section in the low-temperature start-up preheater are independently adjusted by the PID algorithm according to the difference between the target temperature and the real-time temperature, and the opening and closing state of the electric butterfly valve type rotary baffle is controlled in coordination to switch the heat recovery loop. The gas pressure in the hydrogen inlet pipe is adjusted by a pressure reducing valve, and the anode back pressure is stabilized by a solenoid valve. Step 3: Adaptive Adjustment During Operation During operation, the PCB board dynamically adjusts the power of the hydrogen pipeline heating section based on the hydrogen temperature feedback from the second temperature sensor to maintain the hydrogen temperature at 30-40℃; based on the temperature difference between the fuel cell body temperature from the third temperature sensor and the first temperature sensor, it adjusts the cathode fan speed and the power of the cathode recovery gas heating section to maintain system thermal balance; during the operation of the fuel cell body, the power of the hydrogen pipeline heating section is dynamically adjusted with the goal of maintaining the T1 of the second temperature sensor at 30-40℃. With the goal of maintaining the stack body temperature T2 within a reasonable operating range, the cathode fan speed and the auxiliary heating power of the cathode recovery gas heating section are adjusted. Step 4: Shutdown, purging, and anti-icing protection Upon receiving a shutdown command, the shutdown purging protection program is initiated. The preheater is heated at low temperature and the cathode fan and booster fan are started at high speed for purging according to a predetermined sequence until the humidity sensor or equivalent judgment conditions inside the system meet the drying requirements, preventing residual moisture from freezing after shutdown.

[0014] The beneficial effects of this invention are: 1. By independently preheating the cathode and anode and combining it with heat recovery, the gas temperature is controlled throughout the process, improving cold start efficiency. This enables rapid and reliable cold start in low-temperature environments from -20℃ to 0℃, significantly shortening start-up time and avoiding damage to the fuel cell stack caused by icing.

[0015] 2. By utilizing waste heat recovery and intelligent mode switching, the auxiliary energy consumption for low-temperature startup is significantly reduced, thereby improving the overall energy efficiency of low-power systems.

[0016] 3. The system can intelligently switch between three start-up modes based on ambient temperature to adapt to different low-temperature environments. The control system is responsive and highly adaptive, and can automatically optimize operating parameters according to the external environment and internal status, thereby improving the robustness of the system under different operating conditions.

[0017] 4. It has a compact structure and high component integration, making it particularly suitable for low-power air-cooled PEMFC applications where size and weight are critical.

[0018] 5. A complete shutdown protection mechanism extends the service life of the fuel cell stack under intermittent operation conditions. During shutdown, residual moisture is quickly removed through heating and fan purging to prevent freezing and improve the restart speed. By combining preheating technology, two-stage heating, heat recovery and intelligent temperature control, the fuel cell can be started up quickly and shut down safely in environments below 0°C. Attached Figure Description

[0019] Figure 1This is an overall schematic diagram of a low-power air-cooled fuel cell rapid low-power consumption low-temperature cold start system according to the present invention; Figure 2 This is another overall schematic diagram of a low-power air-cooled fuel cell rapid low-power consumption low-temperature cold start system according to the present invention; Figure 3 This is another overall schematic diagram of a low-power air-cooled fuel cell rapid low-power consumption low-temperature cold start system according to the present invention; Figure 4 This is a schematic diagram of a low-temperature start-up preheating component for a low-power air-cooled fuel cell rapid low-power consumption low-temperature cold start system according to the present invention. Explanation of reference numerals in the attached figures: 1. Cathode fan; 2. Electric butterfly valve rotary baffle; 3. Low-temperature start-up preheater; 3-1. Cathode recovery gas heating section; 3-2. Hydrogen pipeline heating section; 4. Cathode gas heat recovery pipeline; 5. Stack body; 6. Hydrogen inlet pipe; 7. Inner wall thermal conductive coating; 8. Outer wall insulation material; 9. Manual shut-off valve; 10. Pressure reducing valve; 11. First pressure sensor; 12. DC power supply; 13. Circuit breaker; 14. Hydrogen outlet pipe; 15. Solenoid valve; 16. Second pressure sensor; 17. Anode flow channel inlet; 18. Anode flow channel outlet; 19. First temperature sensor; 20. Second temperature sensor; 21. Third temperature sensor; 22. Fourth temperature sensor; 23. Fifth temperature sensor; 24. Conductive wire; 25. PCB board; 26. Voltage relay; 27. Auxiliary fan; 28. First single-control switch; 29. ​​Second single-control switch. Detailed Implementation

[0020] 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 described embodiments are merely some, not all, of the embodiments of this invention. Unless otherwise specified, the embodiments and features described in this application can be combined with each other. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0021] In one embodiment, see Figure 1 The present invention discloses a low-power air-cooled fuel cell rapid low-power consumption low-temperature cold start system, comprising a fuel cell stack body 5 components, a low-temperature start-up preheating component, and an intelligent control component.

[0022] The fuel cell stack assembly 5 includes a fuel cell stack body 5 and a cathode gas heat recovery pipe 4 located between the outlet and inlet of the fuel cell stack body 5. A cathode fan 1 is installed on the cathode side of the fuel cell stack body 5 and located inside the cathode gas heat recovery pipe 4 to provide oxidant air to the fuel cell stack, assist in heat dissipation, and provide power for the airflow within the cathode gas heat recovery pipe 4. A hydrogen inlet pipe 6 is connected to the anode flow channel inlet 17 of the fuel cell stack body 5, and a hydrogen outlet pipe 14 is connected to the anode flow channel outlet 18 of the fuel cell stack body 5. An auxiliary fan 27 is installed inside the cathode gas heat recovery pipe 4. An electric butterfly valve type rotary baffle 2 is provided at the bypass or switching node of the cathode gas heat recovery pipe 4. By controlling the electric butterfly valve type rotary baffle 2, the fan can provide a rotary baffle for the fuel cell stack body 5. The rotation of the baffle 2 opens and closes the cathode gas heat recovery pipeline 4, which is used to regulate the on / off state of the waste heat recovery circuit. The end of the hydrogen inlet pipe 6 away from the stack body 5 is connected to the hydrogen source and is equipped with a manual shut-off valve 9 and a pressure reducing valve 10 in sequence. The manual shut-off valve 9 is installed downstream of the external hydrogen source and is used to manually control the on / off state of the hydrogen supply pipeline. The pressure reducing valve 10 is installed on the hydrogen inlet pipe 6 downstream of the manual shut-off valve 9 and is used to precisely adjust the hydrogen inlet pressure entering the stack anode. A first pressure sensor 11 is provided between the manual shut-off valve 9 and the pressure reducing valve 10, and a second pressure sensor 16 is provided on the hydrogen outlet pipe 14. The first pressure sensor 11 is installed upstream of the pressure reducing valve 10 and is used to monitor the gas source output pressure.

[0023] The low-temperature start-up preheater 3 includes a cathode recovery gas heating section 3-1 and a hydrogen pipeline heating section 3-2. The hydrogen inlet pipe 6 is located within the cathode gas heat recovery pipe 4 and the hydrogen pipeline heating section 3-2. It independently preheats the recovery gas / air flowing into the cathode of the fuel cell stack 5 and the hydrogen flowing into the anode. The steady-state operating temperature of the cathode recovery gas heating section 3-1 is set at 90℃±3℃, and the upper limit of the heating temperature of the hydrogen pipeline heating section 3-2 is 40℃. The low-temperature start-up preheater 3 integrates independent heating sections for the cathode circulating gas / air and the anode hydrogen, which can work independently or in combination as needed, achieving precise and efficient preheating of the reaction gases. The hydrogen heating temperature is limited to below 40℃ to ensure safety.

[0024] The intelligent control component includes a PCB board 25 electrically connected to the low-temperature start-up preheating component. A solenoid valve 15 is provided between the PCB board 25 and the hydrogen outlet pipe 14. An electric butterfly valve rotary baffle 2, a first pressure sensor 11, a second pressure sensor 16, a cathode fan 1, and a solenoid valve 15 are electrically connected to the PCB board 25. A first temperature sensor 19, a second temperature sensor 20, a third temperature sensor 21, a fourth temperature sensor 22, and a fifth temperature sensor 23 electrically connected to the PCB board 25 are provided in the cathode gas heat recovery pipe 4, on the hydrogen inlet pipe 6, on the anode side of the fuel cell stack body 5, on the hydrogen pipeline heating section 3-2, and on the cathode recovery gas heating section 3-1, respectively.

[0025] The cathode gas heat recovery pipeline 4 is quickly switched on and off using an electric butterfly valve-type rotary baffle 2. In the initial stage of ultra-low temperature start-up, the cathode gas heat recovery pipeline 4 can be isolated from the external environment to prevent cold air backflow. After the fuel cell stack body 5 heats up or during normal temperature start-up, the ambient gas passage can be opened appropriately or completely to recover waste heat from the exhaust gas for preheating the inlet air, significantly reducing external heating energy consumption.

[0026] It should be noted that the solenoid valve 15 is installed on the hydrogen outlet pipe 14 of the anode of the fuel cell stack to maintain the pressure in the anode flow channel within a stable range of 0.1~0.3 MPa and prevent abnormal pressure.

[0027] It should be noted that the second pressure sensor 16 is installed upstream of the solenoid valve 15 and connected to the PCB board 25, and is used to monitor the outlet pressure of the anode flow channel.

[0028] The temperature sensor group includes a first temperature sensor 19 for detecting the ambient / recovery gas temperature, a second temperature sensor 20 for detecting the intake hydrogen temperature, a third temperature sensor 21 for detecting the temperature of the fuel cell stack body 5, a fourth temperature sensor 22 for detecting the temperature of the hydrogen pipeline heating section 3-2, and a fifth temperature sensor 23 connected to the PCB board 25 for detecting the temperature of the cathode recovery gas heating section 3-1. The cathode fan 1 is used to assist in enhancing the airflow power of the system. The voltage relay 26 is connected in series with the circuit breaker 13 and connected to the PCB board 25 for short circuit and overvoltage protection, so as to realize independent closed-loop PID negative feedback control and achieve precise control of temperature and time decoupled.

[0029] The PCB board 25 is connected to the electric butterfly valve rotary baffle 2, pressure reducing valve 10, first pressure sensor 11, second pressure sensor 16, solenoid valve 15, various temperature sensors (19, 20, 21, 22, 23), circuit breaker 13, and the voltage signal of the fuel cell stack 5. It receives sensor signals and executes predetermined low-temperature cold start and operation control strategies via instructions from a directly connected host computer. The control strategy, centered on the PCB board 25, intelligently judges and switches between "preheating protection mode," "low-power preheating start mode," and "normal start mode" based on real-time monitoring of ambient temperature, fuel cell stack 5 temperature, gas temperature, pressure, and fuel cell stack 5 voltage. During operation, system thermal and water balance is achieved by adjusting heating power, fan speed, and valve opening.

[0030] The unique shutdown process uses resistance wire heating to evaporate residual liquid water and cathode fan 1 to force purging, quickly reducing the humidity inside the system and effectively preventing icing after shutdown, thus creating conditions for the next rapid restart.

[0031] Furthermore, the inner wall of the cathode gas heat recovery pipe 4 is provided with an inner wall thermal conductive coating 7, and the outer wall of the cathode gas heat recovery pipe 4 is provided with an outer wall insulation material 8 made of ceramic fiber or polyurethane foam, with a heat recovery efficiency of not less than 50%, which is used to efficiently recover the waste heat generated by the operation of the fuel cell stack 5 and preheat the inlet gas.

[0032] Furthermore, it also includes a DC power supply 12, a circuit breaker 13 connected in series in the power supply circuit between the DC power supply 12 and the low-temperature start-up preheater 3, a first single-control switch 28 and a second single-control switch 29 connected between the DC power supply 12 and the cathode gas recovery heating section and between the hydrogen pipeline heating section 3-2, respectively; a voltage relay 26 is electrically connected between the DC power supply 12 and the PCB board 25, and the DC power supply 12 provides working power to the low-temperature start-up preheater 3; the circuit breaker 13 is connected in series in the power supply circuit between the DC power supply 12 and the low-temperature start-up preheater 3, and is used to control the start and stop of the preheater and circuit protection; the first single-control switch 28 and the second single-control switch 29 control the heating of the cathode gas recovery circuit and the hydrogen pipeline, respectively.

[0033] Furthermore, both the cathode recovery gas heating section 3-1 and the hydrogen pipeline heating section 3-2 adopt resistance wire heating, and the heating power is independently adjustable, with power ranges of 0.5~2.0 kW and 0.2~1.0 kW, respectively.

[0034] like Figure 1 As shown, this system constructs a composite thermal management platform that integrates active heating, waste heat recovery, pressure management, and intelligent control.

[0035] The system uses PCB board 25 as the decision-making center, continuously collecting real-time data from the first temperature sensor 19, the second temperature sensor 20, the third temperature sensor 21, the fourth temperature sensor 22, the fifth temperature sensor 23, the first pressure sensor 11, the second pressure sensor 16, and the voltage of the fuel cell stack 5. Based on the key initial criterion of ambient temperature T, PCB board 25 executes a preset multi-mode control strategy. One of its core actions is to control the opening and closing of the electric butterfly valve rotary baffle 2, thereby switching between two basic gas path topologies, corresponding to the following three implementation cases.

[0036] System workflow and control strategy implementation examples: Operating Condition 1: PCB board 25 acquires the ambient temperature T from the first temperature sensor 19. Startup occurs when the ambient temperature is -5℃ (T < 2℃). When the PCB board is powered on at 25°C, the temperature is read as T = -5°C, and it automatically enters the "preheating protection mode".

[0037] PCB board 25 controls the electric butterfly valve type rotary baffle 2 to rotate to the closed position, cutting off the cathode gas heat recovery pipeline 4.

[0038] PCB board 25 closes circuit breaker 13 and starts low temperature start preheater 3; cathode recovery gas heating section 3-1 and hydrogen pipeline heating section 3-2 start working simultaneously, heating circulating air and hydrogen at rated power respectively.

[0039] The cathode fan 1 operates at low speed, promoting air circulation in the heating loop formed by the low-temperature start-up preheater 3.

[0040] PCB board 25 continuously monitors the stack temperature T2 of the third temperature sensor 21. When T2 > 5°C, the preheating stage is completed.

[0041] Subsequently, the system can switch to "low-power preheating start-up mode" or directly attempt to start the fuel cell stack with low power according to the strategy.

[0042] Operating Condition 2: Start-up at an ambient temperature of 5℃ (2℃ ≤ T < 10℃) PCB board 25 determines that it has entered "low power preheating start mode".

[0043] The electric butterfly valve type rotary baffle 2 is controlled to rotate 45° to open, connecting the cathode gas heat recovery pipeline 4 to the external environment.

[0044] The cathode recovery gas heating unit 3-1 is activated to provide auxiliary heating for the intake gas, while the hydrogen pipeline heating unit 3-2 can be operated at low power or shut down as needed.

[0045] Turn on the hydrogen supply (open the pressure reducing valve to the predetermined opening degree) and start the fuel cell stack to operate at a lower load (such as 20%-30% of the rated power).

[0046] During operation, the heating power and fan speed are dynamically fine-tuned based on the stack temperature T2 and the hydrogen inlet temperature T1 using a PID algorithm on PCB board 25.

[0047] Operating Condition 3: Normal operation and anode water management, ambient temperature T≥ 10℃.

[0048] During normal operation of the fuel cell stack, the PCB board 25 continuously monitors the stack voltage. During operation, the PCB board 25 dynamically adjusts the power of the hydrogen pipeline heating section 3-2 based on the hydrogen temperature feedback from the second temperature sensor 20 to maintain the hydrogen temperature at 30-40℃. Based on the temperature difference between the stack body 5 temperature measured by the third temperature sensor 21 and the first temperature sensor 19, the PCB board 25 adjusts the speed of the cathode fan 1 and the power of the cathode recovery gas heating section 3-1 to maintain system thermal balance.

[0049] Operating Condition 4: Shutdown Process Upon receiving the shutdown command, PCB board 25 first disconnects the fuel cell load and shuts down the output of fuel cell body 5.

[0050] Start the shutdown purging procedure: maintain hydrogen supply for a short time, and at the same time start the low temperature start-up preheater 3 (mainly the cathode gas heating part) to heat the pipeline and evaporate the liquid water.

[0051] The cathode fan 1 and the booster fan 27 are controlled to run at high speed, which powerfully blows the generated water vapor out of the system.

[0052] The purging continues for a predetermined time or until the estimated internal humidity of the system falls below the anti-icing threshold.

[0053] Finally, close the pressure reducing valve and manual shut-off valve 9, stop the hydrogen supply and disconnect all power to complete the safe shutdown.

[0054] Implementation Case 1: Cold Start and Ultra-Low Temperature Protection Mode (Electric Butterfly Valve Rotary Baffle 2 Closed) Operating conditions triggering conditions: When the system is powered on and initialized, when the ambient temperature T detected by the first temperature sensor 19 is less than 2℃, the PCB board 25 determines that it has entered the initial stage of the "preheating protection mode" or "low power preheating start mode". At this time, it controls the electric butterfly valve type rotary baffle 2 to rotate 90° to put it in the closed state.

[0055] System status: In this status, such as Figure 1In Case 1 (with the electric butterfly valve rotary baffle 2 closed), the inlet of the cathode gas heat recovery pipe 4 is physically blocked. The cathode gas flow cannot return through this pipe, and the system changes from an "open loop" to a "closed / semi-closed loop". The air (or initial circulating gas) flow path driven by the cathode fan 1 and the auxiliary fan 27 is confined to an internal loop consisting of the cathode of the fuel cell stack 5, the cathode recovery gas heating section 3-1 of the cryogenic start-up preheater 3, and the connecting pipes.

[0056] Operating principle and process: Airflow organization and sealing preheating: After the electric butterfly valve-type rotary baffle 2 is closed, a well-sealed preheating chamber is formed inside the system. The cathode fan 1 starts, driving the gas (initially cold air) to circulate within this closed loop. This effectively prevents the continuous intrusion of extremely cold external air and greatly reduces system heat loss.

[0057] Active staged heating: Simultaneously, PCB board 25 activates the low-temperature preheater 3 and precisely controls the cathode recovery gas heating unit 3-1 to operate at a higher power (e.g., 0.8-1.5 kW) to rapidly and centrally heat the circulating gas. Simultaneously, the hydrogen pipeline heating unit 3-2 is activated to preheat the hydrogen in the hydrogen inlet pipe 6 at a limited power (maintaining an outlet temperature ≤40℃) to prevent excessively low hydrogen temperatures and pipeline ice blockage. Heat is efficiently retained within the system, and the gas temperature continuously rises in the loop.

[0058] Target-oriented temperature rise: The core objective of this mode is to rapidly increase the temperature of the fuel cell stack 5. Heated circulating gas flows through the cathode channel of the fuel cell stack 5, transferring heat to the membrane electrode assembly (MEA) and bipolar plates via convection. A third temperature sensor 21 monitors the fuel cell stack temperature (T2) in real time. The control strategy uses T2 > 5°C (adjustable) as the indicator that the first stage of preheating is complete.

[0059] Pressure Management and Hydrogen Preparation: During the preheating process, the hydrogen subsystem is prepared synchronously. Manual shut-off valve 9 is opened, and pressure reducing valve 10 is adjusted to the preset opening degree, providing preheated hydrogen with stable pressure to the anode of the fuel cell stack 5. Solenoid valve 15 ensures back pressure safety.

[0060] Implementation Case 1: This case demonstrates the system's adaptive sealing and enhanced preheating capabilities at extremely low temperatures. By sealing the cathode gas heat recovery pipe 4 from the external environment, the heating efficiency degradation caused by "cold backflow" in the early stages of low-temperature startup is avoided. This achieves efficient heat accumulation and directional heat transfer, laying a crucial thermal foundation for the rapid, low-energy activation of the fuel cell stack below freezing point.

[0061] Implementation Case 2: Temperature Zone Transition and Mixed Intake Mode (Electric Butterfly Valve Rotary Baffle 2 Half Open) Operating condition triggering condition: When the system starts up or runs, if the ambient temperature T detected by the first temperature sensor 19 meets the condition 2℃ ≤ T < 10℃, the PCB board 25 determines that it has entered the "low-power preheating start-up mode" or "temperature zone transition mode". In this mode, the PCB board 25 precisely controls the electric butterfly valve rotary stop 2 to rotate to an intermediate angle (e.g., 45°), placing it in a half-open state. System status: In this state, such as... Figure 2 Case 2 illustrates the partial opening of the electric butterfly valve rotary baffle 2. The inlet of the cathode gas heat recovery pipe 4 and the external environment (i.e., the portion of the fuel cell stack 5 where the cathode directly faces the external environment) are both partially open. The system forms a mixed parallel airflow path, neither a completely closed loop nor a completely open direct path. Operating principle and process: Mixed airflow organization and dynamic balance: With the electric butterfly valve rotary baffle 2 partially open, the cathode airflow is split. One portion of the airflow (mainly the high-temperature exhaust gas from the fuel cell stack 5) is guided into the cathode gas heat recovery pipe 4; simultaneously, another portion of the airflow (mainly fresh ambient air) directly enters the cathode intake mainstream through the uncovered opening of the electric butterfly valve rotary baffle 2. The two airflows converge in the upstream area of ​​the cathode intake of the fuel cell stack 5 or in a specific mixing chamber. Controllable proportional heat supply and oxidant supply: The PCB board 25 dynamically adjusts the opening of the electric butterfly valve rotary baffle 2 based on the fuel cell temperature T and the target operating temperature monitored in real time by the third temperature sensor 21. Its core control objective is to maximize the utilization of waste heat from the exhaust gas while ensuring a sufficient supply of fresh air (oxidant), so that the mixed intake air temperature remains stable within the set range. When T is low, the opening of the electric butterfly valve rotary stop 2 can be reduced to favor the recovery side, increasing the heat recovery ratio; when power demand increases and more fresh air is needed, the opening can be increased to increase the proportion of ambient air. Auxiliary preheating and low-power start-up: In the initial stage of this mode's start-up, the PCB board 25 will simultaneously activate the cathode recovery gas heating section 3-1 of the low-temperature start-up preheater 3, using a low auxiliary power to compensate for heating the ambient air branch before mixing or the total intake air after mixing, ensuring that the intake air temperature quickly reaches the start-up threshold at a low ambient temperature. The hydrogen pipeline heating section 3-2 is usually kept on standby or operating at extremely low power. Adaptive operation and efficiency optimization: After the fuel cell stack 5 starts up, as its own heat generation increases, the PCB board 25 can gradually reduce or even shut down the electric auxiliary heating, mainly relying on adjusting the opening of the electric butterfly valve rotary stop 2 to utilize the continuously increasing waste gas heat to maintain the intake air temperature. This mode achieves "on-demand mixing," which avoids the problem of insufficient fresh air that may occur when the system is completely closed, as in Case 1, and has higher heat recovery efficiency and faster heating rate at lower ambient temperatures than when the system is completely open, as in Case 3 below.

[0062] Implementation Case 2: This case demonstrates the system's adaptive energy efficiency optimization and multi-objective collaborative control capabilities in mild and low-temperature ranges. Through continuous or step adjustment of the electric butterfly valve rotary stop 2, the system can achieve a dynamic optimal balance between the two key requirements of heat recovery (energy saving) and reactant supply (ensuring power and preventing oxygen deficiency). This "partial recovery, partial replacement" strategy is particularly suitable for scenarios where the ambient temperature is close to but slightly below the ideal operating temperature limit of the fuel cell stack 5. It significantly widens the temperature window for efficient and stable operation of air-cooled fuel cells and serves as a key intelligent transition mode connecting extreme cold start protection with efficient operation at normal temperatures.

[0063] Implementation Case 3: Normal Start-up Mode (Electric Butterfly Valve Rotary Baffle 2 Fully Open) Operating conditions triggering conditions: When the ambient temperature T ≥ 10℃, or when the fuel cell stack temperature has risen to a safe level after preheating in Implementation Case 1 (e.g., T2 > 10℃), the system switches to "normal startup mode" or "high-efficiency operation mode". At this time, the PCB board 25 controls the electric butterfly valve type rotary baffle 2 to rotate 90° to the fully open state.

[0064] System status: such as Figure 3 As illustrated in Case 3 (with the electric butterfly valve-type rotary baffle 2 fully open), the passage of the cathode gas heat recovery pipe 4 is fully opened, and the system returns to open circulation. The high-temperature exhaust gas from the cathode outlet of the fuel cell stack 5 can flow unimpeded into the recovery pipe.

[0065] Operating principle and process: Waste heat recovery and energy cascade utilization: The high-temperature (typically 60-80℃) cathode exhaust gas generated during the operation of the fuel cell stack 5 is drawn or propelled into the cathode gas heat recovery pipe 4 by the cathode fan 1. The inner wall thermally conductive coating 7 of the pipe enhances the heat transfer process, while the outer wall insulation material 8 reduces heat loss along the way. The high-temperature exhaust gas exchanges heat with the pipe wall, transferring sensible heat to the pipe wall.

[0066] Inlet preheating and energy saving: Fresh, cold air from the environment is preheated by the preheated pipe wall as it flows through the outer side of the cathode gas heat recovery pipe 4 or a specific heat exchange channel. The preheated air then enters the low-temperature start-up preheater 3. At this time, the cathode recovery gas heating section 3-1 only needs to provide compensatory heating (or be completely shut down) to bring the inlet air temperature to the ideal operating range of the fuel cell stack 5. The hydrogen pipeline heating section 3-2 is usually maintained at a very low power as an auxiliary when the inlet air temperature is low.

[0067] Intelligent switching and energy efficiency optimization: In this mode, the main heat source of the system changes from pure "external electric heating" to "waste heat recovery as the main source and electric heating as a supplement". The PCB board 25 dynamically calculates and decides whether to activate and how much power of electric auxiliary heating to activate based on the feedback from the fifth temperature sensor 23 (temperature of gas at the outlet of the recovery pipe) and the third temperature sensor 21 (temperature of the fuel cell stack 5), thereby minimizing the total energy consumption of the system.

[0068] Case Study 3: This case study highlights the system's intelligent energy management and improved operational efficiency. By opening the waste heat recovery loop, the system achieves the recovery and reuse of high-quality thermal energy from the reaction products (exhaust gas), significantly reducing parasitic power consumption in maintaining the system's optimal operating temperature. The rapid switching of the electric butterfly valve-type rotary baffle 2 allows the system to flexibly switch between two thermodynamic states: "rapid cold start" and "efficient steady-state operation," enhancing its adaptability to all operating conditions.

[0069] Overview of Mode Switching and System Advantages The system described in this invention achieves rapid and reliable switching between Case 1 (closed preheating mode), Case 2 (semi-open preheating mode), and Case 3 (normal start-up mode) through the key actuator, an electric butterfly valve-type rotary baffle 2. This switching is not a simple manual operation, but is embedded in an intelligent control algorithm based on multi-sensor feedback, ensuring precise timing and smooth process of mode transition.

[0070] In summary, this specific implementation method is illustrated in detail through two representative cases: In harsh low-temperature environments, the system can overcome the problem of large heat loss in the early stage of cold start by actively sealing off and focusing heating, thus achieving rapid temperature rise.

[0071] Under normal temperature and steady-state operation, the system can maximize the use of the heat generated by the fuel cell stack itself and reduce auxiliary energy consumption by opening loops and recovering waste heat.

[0072] The intelligent control system, which runs throughout the entire process, not only manages heat flow but also integrates features such as automatic shutdown purging and anti-icing, enabling comprehensive management of water, heat, gas, and electricity in the PEMFC.

[0073] This system has a compact structure and clear logic, making it suitable for low-power air-cooled PEMFC applications that are sensitive to size, weight, and energy consumption. It provides an innovative, efficient, and reliable engineering solution to address the bottleneck of low-power consumption and low-temperature applications.

[0074] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A low-power, air-cooled fuel cell rapid low-power consumption cold start system, characterized in that, include: The fuel cell stack assembly includes a fuel cell stack body (5) and a cathode gas heat recovery pipe (4) located between the outlet and inlet of the fuel cell stack body (5). A cathode fan (1) is installed on the cathode side of the fuel cell stack body (5) and located inside the cathode gas heat recovery pipe (4). A hydrogen inlet pipe (6) is connected to the anode flow channel inlet (17) of the fuel cell stack body (5), and a hydrogen outlet pipe (14) is connected to the anode flow channel outlet (18) of the fuel cell stack body (5). An auxiliary fan (27) is installed inside the cathode gas heat recovery pipe (4), and an electric butterfly valve-type rotating baffle (2) is provided on the cathode gas heat recovery pipe (4). The end of the hydrogen inlet pipe (6) away from the fuel cell stack body (5) is connected to a hydrogen gas source and is sequentially equipped with a manual shut-off valve (9) and a pressure reducing valve (10). A first pressure sensor (11) is provided between the manual shut-off valve (9) and the pressure reducing valve (10). A second pressure sensor (16) is provided on the hydrogen outlet pipe (14). The low-temperature start-up preheater (3) includes a cathode recovery gas heating section (3-1) and a hydrogen pipeline heating section (3-2); the hydrogen inlet pipe (6) is located inside the cathode gas heat recovery pipe (4) and inside the hydrogen pipeline heating section (3-2); The intelligent control component includes a PCB board (25) electrically connected to the low-temperature start-up preheater (3); a solenoid valve (15) is provided between the PCB board (25) and the hydrogen outlet pipe (14); the electric butterfly valve type rotary baffle (2), the first pressure sensor (11), the second pressure sensor (16), the cathode fan (1), and the solenoid valve (15) are electrically connected to the PCB board (25) respectively; a first temperature sensor (19), a second temperature sensor (20), a third temperature sensor (21), a fourth temperature sensor (22), and a fifth temperature sensor (23) electrically connected to the PCB board (25) are respectively provided in the cathode gas heat recovery pipe (4), on the hydrogen inlet pipe (6), on the anode side of the stack body (5), on the hydrogen pipeline heating part (3-2), and on the cathode recovery gas heating part (3-1).

2. The low-power air-cooled fuel cell rapid low-power consumption low-temperature cold start system according to claim 1, characterized in that: The inner wall of the cathode gas heat recovery pipe (4) is provided with an inner wall heat-conducting coating (7).

3. The low-power air-cooled fuel cell rapid low-power consumption low-temperature cold start system according to claim 2, characterized in that: The outer wall of the cathode gas heat recovery pipe (4) is provided with an outer wall insulation material (8).

4. A low-power air-cooled fuel cell rapid low-power consumption low-temperature cold start system according to claim 3, characterized in that: The electric butterfly valve type rotary baffle (2) is installed at the bypass or switching node of the cathode gas heat recovery pipeline (4). By rotating, the cathode gas heat recovery pipeline (4) can be opened or completely closed, and is used to control the on / off of the waste heat recovery circuit.

5. A low-power, air-cooled fuel cell rapid low-power consumption low-temperature cold start system according to claim 4, characterized in that: Both the cathode recovery gas heating section (3-1) and the hydrogen pipeline heating section (3-2) adopt resistance wire heating. The heating power of the resistance wire heating is independently adjustable, with power ranges of 0.5~2.0 kW and 0.2~1.0 kW, respectively.

6. A low-power air-cooled fuel cell rapid low-power consumption low-temperature cold start system according to claim 5, characterized in that: The steady-state operating temperature of the cathode recovery gas heating unit (3-1) is set to 90℃±3℃; the upper limit of the heating temperature of the hydrogen pipeline heating unit (3-2) is 40℃.

7. A low-power, air-cooled fuel cell rapid low-power consumption low-temperature cold start system according to claim 6, characterized in that: It also includes a DC power supply (12); a circuit breaker (13) is connected in series in the power supply circuit between the DC power supply (12) and the low temperature start-up preheater (3); a first single-control switch (28) and a second single-control switch (29) are respectively connected between the DC power supply (12) and the cathode gas recovery heating section and the hydrogen pipeline heating section (3-2); a voltage relay (26) is electrically connected between the DC power supply (12) and the PCB board (25).

8. A low-power, air-cooled fuel cell rapid low-power consumption low-temperature cold start system according to claim 7, characterized in that: The pressure of the anode flow channel of the fuel cell stack body (5) is within a stable range of 0.1~0.3 MPa.

9. A cold start control method for a low-power air-cooled fuel cell rapid low-power consumption low-temperature cold start system according to claims 1-8, executed by a PCB board (25), comprising the following steps: Step 1: Temperature Monitoring and Mode Determination When the system is powered on and initialized, the PCB board (25) directly connected to the host computer collects the ambient temperature T of the first temperature sensor (19), the hydrogen inlet temperature T1 of the second temperature sensor (20), the temperature of the fuel cell body (5) T2 of the third temperature sensor (21), the hydrogen heating temperature T3 of the fourth temperature sensor (22), and the cathode gas heating temperature T4 of the fifth temperature sensor (23) in real time. Based on the ambient temperature T, select and enter the corresponding cold start sub-mode: preheating protection mode, low-power preheating start mode, or normal start mode. If the ambient temperature T < 2℃, enter the preheating protection mode: the electric butterfly valve type rotary baffle (2) is in the initial state to close the cathode gas heat recovery pipeline (4) and isolate it from the external environment, start the cathode recovery gas heating part (3-1) and hydrogen pipeline heating part (3-2) of the low temperature start-up preheater (3) to preheat the recovery gas and hydrogen, prohibit the start of the stack body (5) until the temperature of the stack body (5) detected by the third temperature sensor (21) rises to above 2℃; If 2℃ ≤ ambient temperature T < 10℃, enter the low-power preheating start-up mode: control the electric butterfly valve type rotating baffle (2) to rotate 45°, the electric butterfly valve type rotating baffle (2) is half open, so that the cathode heat recovery pipe (4) is connected to the external environment, start the cathode recovery gas heating part (3-1) to preheat the cathode gas inlet; control the stack body (5) to start operation at low power; If the ambient temperature T≥ 10℃, enter the normal start-up mode: control the electric butterfly valve type rotary baffle (2) to rotate 90°, close the low temperature start-up preheater (3), after the electric butterfly valve type rotary baffle (2) rotates, close the upper part of the cathode heat recovery pipe (4), connect the fuel cell body (5) with the external environment, and the fuel cell body (5) starts normally. Step 2: Multi-mode coordinated heating and flow control In the preheating protection mode and the low-power preheating start mode, the heating temperature and heating time of the cathode recovery gas heating section (3-1) and the hydrogen pipeline heating section (3-2) in the low-temperature start preheater (3) are independently adjusted by the PID algorithm according to the difference between the target temperature and the real-time temperature, and the opening and closing state of the electric butterfly valve type rotary baffle (2) is controlled in coordination to switch the heat recovery circuit. The gas pressure in the hydrogen inlet pipe (6) is adjusted by a pressure reducing valve, and the anode back pressure is stabilized by a solenoid valve (15). Step 3: Adaptive Adjustment During Operation During operation, the PCB board (25) dynamically adjusts the power of the hydrogen pipeline heating section (3-2) based on the hydrogen temperature feedback from the second temperature sensor (20) to maintain the hydrogen temperature at 30-40℃; based on the temperature difference between the fuel cell body (5) temperature from the third temperature sensor (21) and the first temperature sensor (19), it adjusts the speed of the cathode fan (1) and the power of the cathode recovery gas heating section (3-1) to maintain the thermal balance of the system; during the operation of the fuel cell body (5), the power of the hydrogen pipeline heating section (3-2) is dynamically adjusted with the goal of maintaining the T1 of the second temperature sensor (20) at 30-40℃; With the goal of maintaining the temperature T2 of the stack body (5) within a reasonable operating range, the rotation speed of the cathode fan (1) and the auxiliary heating power of the cathode recovery gas heating unit (3-1) are adjusted. Step 4: Shutdown, purging, and anti-icing protection Upon receiving the shutdown command, the shutdown purging protection program is initiated to shut down the output of the fuel cell body (5). The low-temperature start-up preheater (3) is controlled according to the predetermined sequence to heat the cathode and hydrogen pipeline, thereby promoting the evaporation of residual moisture. The cathode fan (1) and the auxiliary fan (27) are started to purge at high speed, quickly expelling water vapor from the system until the humidity sensor or equivalent judgment conditions inside the system meet the drying requirements, preventing residual moisture from freezing after shutdown.

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