A self-heating high-temperature methanol fuel cell system

Abstract

This application discloses a self-heating high-temperature methanol fuel cell system, belonging to the field of fuel cell and renewable energy technology. The system uses a closed-loop heat transfer oil circulation loop as a unified heat exchange medium, flowing sequentially through the combustion unit, evaporation unit, and power generation unit to achieve cascaded heat exchange across the entire temperature range. The combustion unit continuously burns fuel using the anode exhaust gas from the fuel cell stack. The heat generated is transferred through the heat transfer oil to the evaporation unit for methanol-water vaporization, and then to the power generation unit to maintain its operating temperature. Feedback is also provided to regulate the reaction temperature of the reforming unit. The system is also equipped with an active temperature control module consisting of a cooler and a three-way valve to dynamically adjust the flow direction and heat dissipation intensity of the heat transfer oil, ensuring that the inlet temperature of each unit remains stable within the optimal reaction window. The reforming unit adopts a tubular structure and is filled with a pre-reduced copper-based composite oxide catalyst. The tubular arrangement meets the requirements for enhanced radial heat transfer, ensuring stable operation of the methanol self-heating reforming at 220-280℃.

Description

Technical Field

[0001] This application relates to a self-heating high-temperature methanol fuel cell system, belonging to the field of fuel cell and renewable energy technology. Background Technology

[0002] The current state of the technology in this invention's technical field is as follows: In distributed and mobile hydrogen energy power systems, methanol is widely used as a hydrogen carrier for on-site hydrogen production due to its advantages such as being a liquid at room temperature, having a high volumetric energy density (approximately 4.4 kWh / L), being safe for storage and transportation, and having good compatibility with existing oil infrastructure; the current mainstream technical route adopts methanol steam reforming (Methanol Steam Reforming, MSR (Medium-Slow Ratio) combined with low-temperature proton exchange membrane fuel cells (LT-PEMFC) or high-temperature proton exchange membrane fuel cells (HT-PEMFC) cascade systems, in which the reforming stage often uses a fixed-bed catalytic reactor, with copper-based catalysts such as CuO-ZnO-Al2O3 to achieve the catalytic conversion of methanol and water vapor at 200-300℃ to generate hydrogen-rich reformed gas; in terms of thermal management, conventional systems generally rely on electric heaters to initially heat up the evaporator and reformer, and regulate the temperature of each unit separately through air preheaters, water-steam heat exchangers or multi-stage independent heat transfer medium loops to meet the different temperature requirements of evaporation (~100℃), reforming (220-280℃) and stack (160-180℃).

[0003] However, the aforementioned technical solutions have revealed several inherent limitations that are difficult to reconcile when expanding to kilowatt-level and above power: First, multi-source distributed thermal management results in long system pipelines, large thermal inertia, and significant heat loss, especially in fixed-bed reformers where radial temperature gradients exceeding 50°C are easily formed, causing local hot spots and accelerating catalyst sintering deactivation; Second, the system's cold start is highly dependent on external electric heating, with electric auxiliary power consumption typically accounting for 8%-10% of the rated power during the start-up phase, severely weakening net power generation efficiency, and exhibiting slow ignition response and long heating and steady-state establishment cycles; Third, anode exhaust gas is usually only used for simple combustion and venting or inefficient utilization, failing to incorporate its contained chemical energy and sensible heat into the system-level thermal balance closed loop, resulting in low overall energy utilization; Fourth, in application scenarios such as vehicles and ships with stringent requirements for volumetric power density, dynamic response, and operational reliability, existing systems struggle to simultaneously achieve multiple objectives such as rapid start-up, compact integration, low CO emissions, and long-life stable operation. Summary of the Invention

[0004] According to one aspect of this application, a self-heating high-temperature methanol fuel cell system is provided. The technical problem solved by this invention is how to get rid of the dependence on external high-power electric heating in a high-power methanol reforming fuel cell system, achieve rapid start-up and self-heating balance during operation, thereby significantly reducing start-up energy consumption and improving system net efficiency and thermal management reliability.

[0005] To achieve the above objectives, this application provides the following technical solution: This application provides a self-heating high-temperature methanol fuel cell system, including an evaporation unit, a reforming unit, a power generation unit, and a combustion unit connected by pipelines. The system is equipped with a heat transfer oil circulation loop to achieve thermal coupling between the units. The heat transfer oil circulation loop is a closed-loop structure, using high-temperature resistant organic heat transfer oil as the heat exchange medium. It flows sequentially through the combustion unit, the evaporation unit, and the power generation unit before returning to the combustion unit, forming a full-process temperature zone stepped heat exchange path. The fuel inlet of the combustion unit is connected to the anode exhaust gas outlet of the power generation unit and is configured to continuously burn the anode exhaust gas as the main fuel. The heat generated is transferred to the evaporation unit via heat transfer oil for the vaporization of methanol aqueous solution, and to the power generation unit to maintain its operating temperature. The reaction temperature of the reforming unit is also regulated by the waste heat feedback of the heat transfer oil. The system is also equipped with a heat transfer oil temperature active control module, including a cooler and a controlled three-way valve. The cooler is located in the heat transfer oil circuit bypass and exchanges heat with the external cooling medium. The three-way valve is configured to dynamically adjust the flow rate of heat transfer oil flowing into the cooler in order to coordinate with the heat output of the combustion unit, so that the outlet steam temperature of the evaporation unit, the inlet reaction gas temperature of the reforming unit, and the anode inlet gas temperature of the power generation unit are stabilized in their respective optimal reaction temperature zones. The reforming unit has a tubular structure, with its catalytic bed filled with a pre-reduced copper-based composite oxide catalyst. The tubular arrangement meets the requirements for enhanced radial heat transfer, thereby suppressing bed hotspots and ensuring that the methanol autothermal reforming reaction proceeds stably at 220–280°C.

[0006] Preferably, the heat transfer oil circulation loop is equipped with a heat transfer oil circulation pump, and the operating temperature range of the high-temperature resistant organic heat transfer oil is 150-320℃.

[0007] Preferably, the cooler is a water-cooled plate heat exchanger, and its cooling water circuit is equipped with a flow regulating valve and a temperature sensor. The temperature sensor is used to monitor the outlet temperature of the heat transfer oil in real time and feed the signal back to the control system to dynamically adjust the opening of the three-way valve.

[0008] Preferably, the combustion unit includes an ignition chamber and a heat exchange chamber; The ignition chamber is equipped with a methanol atomizing nozzle, a flame stabilizer and a high-pressure ignition needle, and the ignition chamber has a first fuel inlet, which is connected to a fresh methanol supply source through a pipeline. The heat exchange chamber has a second fuel inlet, which is connected to the anode exhaust gas outlet of the power generation unit.

[0009] Preferably, the heat exchange cavity is provided with multiple rows of longitudinally arranged metal fins, and the surface of the fins is treated with an Al2O3 or SiC ceramic coating. The heat transfer oil flows in a serpentine flow pattern within the heat exchange chamber, with an elliptical cross-section and a major axis perpendicular to the main flue gas direction.

[0010] Preferably, the reforming unit is a detachable tubular reactor with an inner diameter of 15-25 mm, a wall thickness of 1.0-2.0 mm, and the tube material is 316L austenitic stainless steel or 310S austenitic heat-resistant stainless steel.

[0011] Preferably, the catalyst particles in the reforming unit have a diameter of 3-5 mm, the center-to-center distance between adjacent tubes is 8-20 mm, and the ratio of the center-to-center distance to the particle diameter is 2.5-4.5.

[0012] Preferably, the system is configured to operate sequentially in the following stages: preheating start-up, low-power operation, self-heating balance, and load increase. During the preheating and start-up phase, the combustion unit consumes fresh methanol only through the first fuel inlet for ignition and heating. When the temperature of the heat transfer oil rises to ≥160℃, the system preheating ends. In the low-power stage, methanol is introduced into the evaporation unit for vaporization and mixing with air. The methanol oxidation reaction in the reforming unit heats the reformer and generates hydrogen-rich gas to drive the fuel cell stack unit into a low-power output state. The control system opens the second fuel inlet and simultaneously reduces the supply of fresh methanol, relying on exhaust gas combustion to maintain the system's thermal balance.

[0013] Preferably, during the self-heating equilibrium stage, the control system is configured to coordinately adjust the reforming air flow rate, the heat transfer oil circulation pump speed, and the opening of the three-way valve of the cooler based on the feedback signals from the anode inlet gas temperature sensor of the power generation unit and the reforming unit temperature sensor, so that the bed temperature of the reforming unit is stably maintained at 220-280℃ and the anode inlet gas temperature is stably maintained at 170-182℃.

[0014] Preferably, the system further includes a shutdown control module configured to perform the following safe shutdown operation: The reforming feedstock supply, stack load power, and cathode air flow are sequentially reduced to zero; heat transfer oil circulation is maintained during the above process, and the cooler is activated when the heat transfer oil temperature is above 100°C, until the shell temperatures of the evaporation unit, reforming unit, power generation unit, and combustion unit are all ≤100°C.

[0015] Preferably, the shutdown control module is further configured to: When the cathode air flow rate drops to less than 30% of the rated flow rate, nitrogen or excess air is introduced into the combustion chamber of the combustion unit for purging for no less than 60 seconds to remove residual combustible gases and reduce the risk of deflagration.

[0016] Preferably, the power generation unit is a high-temperature proton exchange membrane fuel cell stack, wherein the proton exchange membrane is a composite membrane of polybenzimidazole matrix doped with 85-95 wt% phosphoric acid, the operating temperature is 160-180℃, and it is resistant to carbon monoxide with a volume concentration ≤3%.

[0017] The beneficial effects that this application can produce include: This application fundamentally breaks through the path dependence of traditional methanol fuel cell systems on high-power electric auxiliary heating by constructing a whole-system thermal coupling architecture with closed-loop heat transfer oil as the unified heat medium and establishing a self-heating operation mechanism of "fuel stack anode tail gas as main fuel - heat transfer oil cascade heat transfer - multi-point temperature coordinated regulation".

[0018] Specifically, using high-temperature resistant organic heat transfer oil as the sole heat exchange medium, replacing the dispersed electric heaters, steam generators, and air preheaters, significantly simplifies the thermal management system structure, reduces heat loss and piping complexity, and greatly improves system integration, making it more suitable for space-constrained scenarios such as vehicles, ships, and emergency power supplies. Relying on the efficient combustion of anode exhaust gas, the previously wasted chemical energy is converted into a core heat source to maintain system thermal balance. This not only reduces electric auxiliary power consumption by more than 30% and shortens cold start time by more than 80% during startup, but also achieves a decrease in total methanol consumption and a significant increase in net power generation efficiency under rated operating conditions. This is further enhanced by the directional design of the heat transfer oil circulation path (burner → evaporator unit → power generation unit → return). The introduction of the cooling-three-way valve active temperature control module enables independent, precise, and dynamic control of the evaporation and vaporization temperature, reforming bed temperature, and stack inlet gas temperature. This ensures that each unit always operates within the optimal reaction window, effectively suppressing radial hot spots in the fixed-bed reformer, extending catalyst life, and guaranteeing stable output of the HT-PEMFC in an atmosphere containing trace amounts of CO. Furthermore, this self-heating closed-loop structure naturally possesses excellent dynamic response characteristics and thermal inertia adaptation capabilities. Combined with phased operation logic and safe shutdown strategies, it comprehensively addresses multiple engineering goals such as rapid start-up and shutdown, high power density, low emissions, and long-term reliable operation, providing an innovative and practical system-level solution for the large-scale application of high-temperature methanol fuel cells. Attached Figure Description

[0019] Figure 1 A schematic diagram of the overall principle of a self-heating high-temperature methanol fuel cell system provided in one embodiment of this application; Figure 2 This is a schematic diagram of the working process of a self-heating high-temperature methanol fuel cell system provided in one embodiment of this application. Detailed Implementation

[0020] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments. The components of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0021] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this application, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0022] In existing technologies, methanol reforming fuel cell systems generally employ multiple independent thermal management subsystems (such as electric heaters heating the evaporator, air preheaters heating the cathode inlet gas, and water-cooled plates controlling the stack temperature), resulting in complex piping, low thermal coupling efficiency, and slow start-up response. Especially under high-power conditions, fixed-bed reformers are prone to significant temperature differences due to insufficient radial heat transfer, leading to localized catalyst deactivation. Simultaneously, the energy from the anode exhaust gas is not recovered and utilized at the system level, resulting in thermal energy waste and limiting the overall net efficiency of the system. To address these issues, this application proposes a technical solution that uses closed-loop heat transfer oil as the unified heat medium and anode exhaust gas as the main fuel to achieve end-to-end self-heating balance.

[0023] Please refer to Figure 1-2 As shown, this application provides a self-heating high-temperature methanol fuel cell system, including an evaporation unit, a reforming unit, a power generation unit, and a combustion unit connected by pipelines. The system is equipped with a heat transfer oil circulation loop to achieve thermal coupling between the units. The heat transfer oil circulation loop is a closed-loop structure, using high-temperature resistant organic heat transfer oil as the heat exchange medium. It flows sequentially through the combustion unit, the evaporation unit, and the power generation unit before returning to the combustion unit, forming a full-process temperature zone stepped heat exchange path. The fuel inlet of the combustion unit is connected to the anode exhaust gas outlet of the power generation unit and is configured to continuously burn the anode exhaust gas as the main fuel. The heat generated is transferred to the evaporation unit via heat transfer oil for the vaporization of methanol aqueous solution, and to the power generation unit to maintain its operating temperature. The reaction temperature of the reforming unit is also regulated by the waste heat feedback of the heat transfer oil. The system is also equipped with a heat transfer oil temperature active control module, including a cooler and a controlled three-way valve. The cooler is located in the heat transfer oil circuit bypass and exchanges heat with the external cooling medium. The three-way valve is configured to dynamically adjust the flow rate of heat transfer oil flowing into the cooler in order to coordinate with the heat output of the combustion unit, so that the outlet steam temperature of the evaporation unit, the inlet reaction gas temperature of the reforming unit, and the anode inlet gas temperature of the power generation unit are stabilized in their respective optimal reaction temperature zones. The reforming unit has a tubular structure, with its catalytic bed filled with a pre-reduced copper-based composite oxide catalyst. The arrangement of the tubular components meets the requirements for enhanced radial heat transfer, thereby suppressing hot spots in the bed and ensuring that the methanol autothermal reforming reaction proceeds stably at 220–280°C.

[0024] In this system, the evaporation unit is a plate evaporator (model: SWEP B65FH), formed by stamping from 316L stainless steel, with a single plate heat exchange area of ​​0.65m². 2 The internal flow channel features a herringbone corrugated structure to enhance the turbulence intensity on the heat transfer oil side. Its cold-side inlet connects to a methanol / water mixture delivery pipeline (volume ratio 1:1.2), while its hot-side inlet connects to the high-temperature section of the heat transfer oil circulation loop (from the combustion unit outlet). The heat transfer oil inlet temperature is controlled at 240–260°C to ensure that the methanol-water solution completes flash vaporization within 0.8–1.2 seconds. The reforming unit is a vertical tube reactor (shell material 316L, inner diameter Φ320mm, height 850mm), with a total of 127 tubes arranged, each with an inner diameter of Φ20mm and a wall thickness of 1.2mm. The tube bundles are arranged in an equilateral triangle with a center-to-center distance of 16mm. The tubes are filled with CuO–ZnO–Al2O3 catalyst particles (particle size 4mm, specific surface area 85m²) obtained by pre-reduction in a hydrogen atmosphere at 300°C for 2 hours. 2 / g, Cu loading 45wt%, catalyst bed height 600mm; the power generation unit is an HT-PEMFC stack (model: BALPOREHT-5kW), composed of 200 single cells stacked together, each cell containing a PBI / phosphoric acid composite film (phosphoric acid doping rate 92wt%, thickness 35μm) and a PtCo / C cathode catalyst (Pt loading 0.3mg / cm³). 2 The fuel cell stack includes a carbon paper gas diffusion layer, stainless steel end plates, and hydraulic fastening devices at both ends to ensure a contact resistance of <2 mΩ·cm. 2 The combustion unit is a dual-chamber integrated burner (shell 310S, total length 420mm). The front end is the ignition chamber (volume 180mL), which houses a Bosch high-voltage ignition needle (model: 0221504002, breakdown voltage ≥25kV), a Delphi methanol atomizing nozzle (model: DF-ME120, nozzle diameter 0.18mm, atomization angle 65°), and a nickel-based flame stabilizer (outer diameter Φ80mm, surface laser-etched annular flame stabilizer grooves). The rear end is the heat exchange chamber (with 32 rows of longitudinal fins, fin thickness 0.8mm, height 12mm, spacing 4mm, substrate 310S, surface coated with Al2O3 ceramic coating, thickness 45μm). The heat transfer oil flow channel adopts a serpentine flow design with an elliptical cross-section (major axis 18mm, minor axis 10mm). The flue gas passes axially through the fin gaps, and the heat transfer oil laterally washes the fin surface. The heat transfer oil circulation loop adopts Dowtherm... TMRP organic heat transfer oil (initial boiling point >330°C, thermal decomposition temperature 360°C, kinematic viscosity 5.2cSt at 250°C) is driven by a magnetically driven centrifugal pump (model: IWAKI MTX-40, rated flow rate 12L / min, head 25m), with piping made of Φ22×2mm 316L stainless steel seamless tubing, and a total loop volume of approximately 28L; the cooler is a water-cooled plate heat exchanger (model: APV GP200, effective heat exchange area 2.1m²). 2 (with a pressure rating of 1.6 MPa), its cooling water side is equipped with a Danfoss AVQ electric regulating valve (model: AVQ65, control accuracy ±1%) and a PT100 temperature sensor (the measuring point is located 150 mm downstream of the outlet of the main pipe of the heat transfer oil circuit); the three-way valve is an SMC VQZ2115 pneumatic proportional flow divider valve, which receives the temperature sensor signal through the PLC controller and outputs a 0.02–0.1 MPa air pressure command according to the PID algorithm to adjust the flow rate of heat transfer oil entering the cooler branch in real time (adjustment range 0–100%). This structure allows the heat transfer oil, after absorbing heat from the flue gas at >500°C in the combustion unit, to first be sent to the evaporation unit to provide latent heat of phase change (absorbing heat and cooling down to 220°C), then enter the jacket of the power generation unit to maintain the uniform temperature of the fuel cell stack (absorbing heat and cooling down to 190°C), and finally return to the heat exchange chamber of the combustion unit to participate in the next round of heating. When the load on the fuel cell stack suddenly increases, causing the heat transfer oil to overheat, the three-way valve automatically opens the cooling branch, allowing some of the heat transfer oil to exchange heat with 30°C circulating cooling water through the plate heat exchanger and then cool down to 160°C before flowing back into the main circuit. This stabilizes the outlet steam temperature of the evaporation unit at 110–115°C, the inlet reaction gas temperature of the reforming unit at 250–265°C, and the anode inlet gas temperature of the power generation unit at 180°C ± 1.5°C. This implementation method enables directional, controllable, and tiered transfer of heat energy from the high-temperature combustion zone to the medium- and low-temperature heating zone, completely replacing the traditional multi-source decentralized heating mode. It solves the fundamental problems of low thermal coupling efficiency, difficulty in temperature zone matching, and high system redundancy, significantly improving the overall compactness and thermal management robustness.

[0025] In existing technologies, heat transfer oil circuits lack power assurance and temperature boundary constraints, making it difficult to support the stable flow rate and wide-range tolerance required for multi-temperature zone coordinated operation. This can easily lead to localized overheating and coking, or low-temperature viscous flow failure. To ensure the reliable circulation and thermal stability of the closed-loop heat transfer oil system under all operating conditions, it is necessary to clearly define the circulation power configuration and the applicable range of heat transfer oil properties.

[0026] Preferably, the heat transfer oil circulation loop is equipped with a heat transfer oil circulation pump, and the operating temperature range of the high-temperature resistant organic heat transfer oil is 150–320°C.

[0027] The heat transfer oil circulation pump uses an IWAKI MTX-40 magnetically driven centrifugal pump. The pump body and isolation sleeve are made of Hastelloy C276 alloy, and the permanent magnet is neodymium iron boron (N42SH grade). The maximum allowable operating temperature is 350°C, and the rated speed is 2900 r / min. It is equipped with a frequency converter (model: ABB ACS550) that allows for stepless speed regulation within the range of 15–50 Hz, corresponding to a flow rate adjustment range of 5–25 L / min. The high-temperature resistant organic heat transfer oil used is Dowtherm. TM RP, with a kinematic viscosity of 12.8 cSt at 150°C, meets the pumping fluidity requirements during low-temperature start-up and shutdown; its flash point is >280°C and carbon residue <0.05wt% at 320°C, ensuring no coking or cracking during long-term operation; a nitrogen sealing device (pressure 0.02MPa) is installed on the top of the heat transfer oil storage tank (40L capacity). This combination of pump and heat transfer oil ensures the system operates within ambient temperature ranges. It maintains stable flow and pressure (loop working pressure 0.3–0.6MPa) throughout the entire range from 25°C to full load operation (maximum instantaneous temperature of heat transfer oil 315°C), preventing temperature oscillations in each unit caused by flow fluctuations, and providing a rigid dynamic foundation and safe physical property boundary for the entire process of cascade heat exchange.

[0028] In existing technologies, the temperature of the heat transfer oil is controlled solely by heating from one side of the combustion unit, lacking active heat dissipation capabilities. This makes it unable to cope with the risk of overheating under conditions such as low load on the fuel cell stack or sudden drops in ambient temperature, leading to accelerated performance degradation of key components (such as the fuel cell stack proton exchange membrane and reforming catalyst). To achieve precise bidirectional control of the heat transfer oil temperature, a cooling branch with feedback regulation capabilities needs to be constructed.

[0029] Preferably, the cooler is a water-cooled plate heat exchanger, and its cooling water circuit is equipped with a flow regulating valve and a temperature sensor. The temperature sensor is used to monitor the outlet temperature of the heat transfer oil in real time and feed the signal back to the control system to dynamically adjust the opening of the three-way valve.

[0030] The cooler uses an APV GP200 brazed plate heat exchanger, which is made of 316L stainless steel corrugated plates (single plate size 200×500mm, corrugation depth 2.5mm) stacked by vacuum brazing. The hot side design pressure is 1.0MPa, the cold side design pressure is 0.8MPa, and the heat transfer coefficient reaches 4200W / (m³). 2•K); The cooling water inlet is equipped with a Danfoss AVQ65 electric regulating valve with a 316L stainless steel valve core and EPDM rubber sealing material. The control signal is a 4–20mA current input with a response time of <1.2s. The temperature sensor is an OMEGA PR-19H-1 / 2-12T platinum resistance thermometer (PT100, Class A accuracy, ±0.15°C), installed on a 150mm straight pipe section downstream of the outlet of the main heat transfer oil circuit. The probe is inserted to a depth of 12mm and connected to a Siemens S7-1200 PLC controller with a 3-meter shielded compensation cable. The PLC has a built-in PID control algorithm (sampling period 100ms, proportional band 5°C, integral time 120s, derivative time 8s). It calculates the three-way valve opening command (0–100%) in real time based on the deviation between the set temperature (190°C) and the measured value, and drives the SMC VQZ2115 three-way valve to operate through a 0.02–0.1MPa air pressure signal. This structure enables the heat transfer oil temperature control accuracy to reach ±1.0°C (2σ). When the stack load suddenly drops from 100% to 30%, the heat transfer oil temperature can be restored from 215°C to 192°C within 45 seconds, effectively preventing water vapor condensation on the cathode side of the stack and dehydration of the membrane electrode assembly (MEA), thus ensuring the output stability of HT-PEMFC over a wide load range.

[0031] In existing technologies, combustion units only have a single fuel inlet and a simple flame structure, which cannot simultaneously ensure the reliability of cold start ignition and the combustion stability of the exhaust gas during steady-state operation, resulting in problems such as ignition failure, flame detachment, and incomplete combustion of exhaust gas. To improve the adaptability and safety of the combustion process, the combustion chamber structure and fuel supply path need to be functionally partitioned.

[0032] Preferably, the combustion unit includes an ignition chamber and a heat exchange chamber; the ignition chamber is provided with a methanol atomizing nozzle, a flame stabilizer and a high-pressure ignition needle, and the ignition chamber has a first fuel inlet, which is connected to a fresh methanol supply source through a pipeline; the heat exchange chamber has a second fuel inlet, which is connected to the anode exhaust gas outlet of the power generation unit.

[0033] The ignition chamber is a cylindrical heat-resistant steel cavity (material GH3030, inner diameter Φ85mm, length 120mm), with a front flange connecting to a methanol delivery pipe (Φ6×1mm). The system uses 316L stainless steel tubing, with the end transitioning to the heat exchange chamber via a diffuser section. The methanol atomizing nozzle is a Delphi DF-ME120 type, installed on the central axis of the chamber. The nozzle orifice is laser-drilled to a diameter of 0.18mm, achieving fine atomization with a Sauter average diameter (SMD) of <35μm when combined with a 12MPa fuel supply pressure. The flame stabilizer is a nickel-based high-temperature alloy (Inconel 718) stamped part with an outer diameter of Φ80mm and a thickness of 4mm. Its surface has 16 spiral flame stabilizing grooves, 0.8mm deep and 1.2mm wide, evenly distributed around the circumference, which can force the formation of a recirculation zone to stabilize the flame root. The high-pressure ignition needle is a Bosch 0221504002 type, with an electrode gap of 0.6mm, a discharge energy of 25mJ, and an ignition frequency of 50Hz. The heat exchange chamber is a coaxial cylindrical structure (inner cylinder Φ120mm, outer cylinder Φ240mm). The second fuel inlet is located on the front side wall of the heat exchange chamber, with a ferrule connector (Swagelok). The SS-4-8 direct-connection fuel cell stack anode exhaust gas pipeline (Φ12×1.5mm 316L stainless steel pipe) allows the exhaust gas to be pressurized by a Venturi ejector (throat diameter Φ4mm) before entering the combustion zone. In practical applications, the ignition chamber and heat exchange chamber can also adopt an integrated casting structure (such as using K418 high-temperature alloy), or the flame stabilizer can be replaced with a porous ceramic flame stabilizer (model: CoorsTek F-1200). This application embodiment does not limit this. This dual-chamber structure achieves physical isolation and functional specialization between the start-up and steady-state operation modes: the ignition chamber focuses on achieving high energy density and strong anti-disturbance initial ignition; the heat exchange chamber is optimized to adapt to the stable combustion of low-calorific-value, high-flow-rate, water vapor-containing anode exhaust gas, avoiding thermal interference of the fresh methanol ignition flame on the exhaust gas combustion zone, and significantly improving the system mode switching success rate and combustion stability.

[0034] In existing technologies, burner heat exchange chambers generally employ bare tubes or simple fin structures. These structures result in low heat transfer coefficients between high-temperature flue gas and heat transfer oil, and the fins are prone to oxidation and detachment under repeated thermal shocks at temperatures exceeding 500°C, leading to rapid degradation of heat exchange efficiency and short service life. To improve the efficiency of high-temperature flue gas waste heat recovery and ensure long-term service reliability, it is necessary to strengthen the design of the internal flow channels and surface treatment of the heat exchange chamber.

[0035] Preferably, the heat exchange cavity is provided with multiple rows of longitudinally arranged metal fins, and the surface of the fins is treated with Al2O3 or SiC ceramic coating; the heat transfer oil flows in a serpentine flow structure in the heat exchange cavity, and the cross-section of the flow channel is elliptical, with the major axis direction perpendicular to the mainstream direction of the flue gas.

[0036] The heat exchange cavity is equipped with 32 rows of longitudinal fins made of 310S material, with a thickness of 0.8 mm and a height of 12 mm. The spacing between adjacent fins is 4 mm. The fin roots are connected to the inner wall of the heat exchange cavity using vacuum diffusion welding (welding temperature 1120°C, pressure 5 MPa, holding time 30 min), and the weld shear strength is >420 MPa. The fin surface is coated with an Al2O3 ceramic coating using atmospheric plasma spraying (APS) process, with a spraying power of 45 kW, a powder feeding rate of 35 g / min, and a coating thickness of 45 ± 5 mm. The micrometer diameter is μm, the porosity is <3%, and the microhardness is 1250HV0.3. The heat transfer oil channel is composed of the inner cylinder outer wall and fins, forming 12 series U-shaped bends in a serpentine path with a total flow length of 8.4m. The channel cross-section is elliptical (major axis 18mm, minor axis 10mm), with the major axis strictly perpendicular to the axial flow direction of the flue gas, forcing the heat transfer oil to generate a strong secondary flow. A guide cone (apex angle 60°) is set at the flue gas side inlet to ensure that the high-temperature flue gas (peak temperature 580°C) is evenly distributed to each fin channel. This structure increases the overall heat transfer coefficient of flue gas-heat transfer oil to 860W / (m²). 2 The efficiency of the heat exchanger is 3.2 times higher than that of a bare tube structure. The Al2O3 coating can operate stably for more than 10,000 hours in an oxidizing environment at 500–600°C, avoiding fin brittle fracture caused by high-temperature oxidation of the base metal. The elliptical cross-section serpentine flow channel has a 28% higher Nusselt number (Nu) than the circular tube flow channel under the same pressure drop, significantly enhancing convective heat transfer. In practical applications, the ceramic coating can also be SiC (with spraying parameters adapted and adjusted), and the fin arrangement can be replaced with a staggered arrangement; this application does not limit this. This implementation significantly improves the high-temperature waste heat recovery efficiency and the long-term reliability of the heat exchange structure, providing key hardware support for the continuous and stable power supply of the heat transfer oil.

[0037] In existing technologies, reformers generally adopt an integral fixed-bed or fluidized-bed structure. The selection of tube dimensions and materials has not been optimized for the strong exothermic characteristics and high-temperature water vapor corrosion environment of methanol autothermal reforming, which can easily lead to tube wall creep, catalyst sintering, and excessive radial temperature difference. To ensure efficient, uniform, and long-life operation of the reforming reaction, the tube geometry parameters and engineering materials need to be designed collaboratively.

[0038] Preferably, the reforming unit is a detachable tubular reactor with an inner diameter of 15–25 mm, a wall thickness of 1.0–2.0 mm, and the tube material is 316L austenitic stainless steel or 310S austenitic heat-resistant stainless steel.

[0039] The reforming unit shell is made of 316L austenitic stainless steel with a wall thickness of 16mm. The flanges at both ends conform to ANSI 150# standard. There are 127 tubes in total, arranged in an equilateral triangle with a center distance of 16mm. Each tube is made of 316L austenitic stainless steel, manufactured by cold drawing, intermediate annealing, and final straightening processes. The inner diameter is Φ20mm (tolerance ±0.05mm), the wall thickness is 1.2mm (tolerance ±0.03mm), and the straightness is ≤0.3mm / m. Both ends are welded with 316L stainless steel tube sheets (tube sheet thickness 40mm, tube holes are precision machined by CNC boring machine with a diameter of Φ20). 15mm, roughness Ra0.8μm); the tubes and tube sheet are connected by a combination of strength welding and expansion (welding current 140A, argon protection, weld leg height 1.5mm; expansion pressure 85MPa) to ensure zero leakage under high temperature and high pressure (design pressure 2.5MPa, design temperature 300°C); before the catalyst is loaded, the inner wall of the tubes is roughened by sandblasting (Sa2.5 grade) and coated with a γ-Al2O3 transition layer (thickness 8μm) to improve the adhesion strength of the catalyst. Under operating conditions of 250°C and 2.0 MPa, the temperature gradient of the tube wall is <8°C / mm, far lower than that of conventional 304 stainless steel tubes (gradient >15°C / mm under the same conditions). The high-temperature yield strength of Inconel 600 (245 MPa at 300°C) is 1.77 times that of 304 stainless steel (138 MPa), effectively suppressing creep deformation during long-term operation. The S31008 shell has an oxidation resistance life of over 30,000 hours in high-temperature environments containing water vapor. In practical applications, Haynes 230 alloy can also be used as the tube material, with inner diameters of Φ18mm or Φ22mm; this embodiment does not limit this. This implementation ensures the mechanical integrity, heat transfer uniformity, and long-term operational reliability of the reformer under harsh operating conditions from both material and structural dimensions.

[0040] In existing technologies, the lack of quantitative matching between catalyst particle size and tube arrangement parameters in reforming beds leads to high radial heat transfer resistance, high pressure drop, and concentrated hot spots, affecting CO selectivity and catalyst lifetime. To achieve uniform bed temperature field and optimized reaction kinetics, precise design of the particle size and tube spatial relationship is required.

[0041] Preferably, the catalyst particles in the reforming unit have a diameter of 3–5 mm, the center-to-center distance between adjacent tubes is 8–20 mm, and the ratio of the center-to-center distance to the particle diameter is 2.5–4.5.

[0042] The catalyst, prepared as CuO–ZnO–Al2O3 particles via co-precipitation, was reduced with hydrogen at 300°C and then sieved to obtain a 4mm particle size range (deviation ±0.2mm), with a sphericity >0.92 and a bulk density of 1.35g / cm³. The center-to-center distance between the tubes was set to 16mm, with a ratio of 4.0 to the particle diameter. The tube array was arranged in an equilateral triangle, and the tube sheet openings were machined using a coordinate boring machine, with a positional error ≤±0.03mm. Vacuum vibration filling was used during loading (vibration frequency 50Hz, amplitude 0.8mm, vacuum degree...). (0.095MPa), ensuring a bed porosity of 62±2% and a radial heat transfer coefficient of 1.85W / (m·K); comparative experiments show that when the center-to-particle diameter ratio is <2.5, inter-tube radiative heat transfer dominates, and the radial temperature difference increases; when it is >4.5, convective heat transfer weakens, the pressure drop decreases, but the risk of hot spots increases; when the ratio is 4.0, at 250°C, 2.0MPa, and GHSV=5000h... -1 Under operating conditions, the maximum radial temperature difference of the bed is only 18°C ​​(50 mm from the central axis), a 63% reduction compared to the conventional design (ratio 6.0), and the CO volume concentration remains stable at 0.8–1.2%, meeting the inlet requirements of HT-PEMFC. In practical applications, the particle diameter can be selected as 3 mm or 5 mm, and the center distance can be adjusted accordingly to 7.5 mm or 22.5 mm; this embodiment does not limit these options. This implementation achieves an optimal balance between heat transfer, pressure drop, and reaction performance through quantitative coordination of geometric parameters, providing structural assurance for low CO, high hydrogen yield, and long-life reforming.

[0043] In existing technologies, the system startup process lacks clear phase divisions and fuel switching logic, which easily leads to problems such as competition between fresh methanol and exhaust gas combustion, temperature runaway, and catalyst thermal shock, resulting in a high startup failure rate and poor repeatability. To achieve controllability and robustness in the startup process, a phased operation strategy based on temperature thresholds needs to be established.

[0044] Preferably, the system is configured to operate sequentially in the following stages: preheating start-up, low-power operation, self-heating balance, and load increase. During the preheating and start-up phase, the combustion unit ignites and heats up by consuming fresh methanol only through the first fuel inlet. When the temperature of the heat transfer oil reaches ≥160°C, the system preheating ends. During the low-power phase, the evaporation unit introduces methanol for vaporization and mixes it with air. The methanol oxidation reaction in the reforming unit heats the reformer and generates hydrogen-rich gas to drive the fuel cell stack unit into a low-power output state. The control system opens the second fuel inlet and simultaneously reduces the supply of fresh methanol, relying on exhaust gas combustion to maintain the system's thermal balance.

[0045] Preheating and start-up phase: Start the heat transfer oil circulation pump (frequency 25Hz), and turn on the combustion air pump (air volume 80Nm).3 / h), the high-voltage ignition needle discharges, and the methanol atomizing nozzle injects methanol into the ignition chamber at a flow rate of 0.12 kg / h, forming a stable blue flame; the combustion flue gas heats the heat transfer oil, causing its temperature to rise at a rate of 12°C / min; when the PT100 sensor detects that the heat transfer oil outlet temperature is ≥160°C (lasting for 30s), the PLC triggers the low-power operation stage; during the low-power operation stage: the control system opens the second fuel inlet solenoid valve (model: Bürkert Type 297) at a rate of 5% increase every 10s, while simultaneously closing the first fuel inlet regulating valve at a rate of 3% decrease every 10s, and the anode exhaust gas flow rate gradually increases from 0 to 2.8 Nm. 3 The fresh methanol flow rate linearly decreases from 0.12 kg / h to 0.018 kg / h (i.e., tail gas percentage ≥ 85%). At this time, the fuel cell stack outputs 0.8 kW power at 160°C, and the generated anode tail gas (CH3OH: 0.29%, H2O: 30.01%, O2: 0%, N2: 27.28%, H2: 13.99%, CO: 1.15%, CO2: 27.28%) becomes the main fuel for combustion. Self-heating equilibrium stage: When the temperature sensor reading in the middle of the reformer bed reaches 250°C and stabilizes for 120 seconds, the system enters the self-heating equilibrium stage. At this time, the first fuel inlet is closed, and the system relies entirely on tail gas combustion for heating. Load increase stage: The methanol / water feed pump, reforming air pump, and fuel cell stack cathode fan speed are increased synchronously according to the preset slope (500 W / min), the heat transfer oil temperature is maintained at 190°C, and the fuel cell stack output power is steadily increased to the rated value of 5 kW. The four-stage logic is solidified through a PLC program. The switching of each stage is based on temperature as a rigid criterion, avoiding subjective operation errors and stabilizing the cold start time at 3.2–3.5 min (62% shorter than the traditional electric heating solution of 8.7 min). The success rate of starting on the first attempt is >99.8%.

[0046] In existing technologies, the temperature fluctuation of the inlet gas in the fuel cell stack under self-heating equilibrium conditions is large, which can easily lead to dehydration or flooding of the proton exchange membrane, affecting the stability and lifespan of the output voltage. To ensure constant temperature gas supply for HT-PEMFC under varying operating conditions, a multi-variable coordinated control mechanism of temperature, flow rate, and rotational speed needs to be established.

[0047] Preferably, during the self-heating equilibrium stage, the control system is configured to coordinately adjust the reforming air flow rate, the heat transfer oil circulation pump speed, and the opening of the three-way valve of the cooler based on the feedback signals from the anode inlet gas temperature sensor of the power generation unit and the reforming unit temperature sensor, so that the bed temperature of the reforming unit is stably maintained at 220-280°C and the anode inlet gas temperature is stably maintained at 170-182°C.

[0048] A type K thermocouple (accuracy ±0.5°C) is installed at the anode inlet of the power generation unit, inside the gas distribution chamber at the front end of the fuel cell stack. The control system employs a dual-closed-loop PID strategy: the outer loop is a temperature loop (set value 180°C), which calculates the target return temperature of the heat transfer oil (190°C ±0.5°C) after acquiring thermocouple signals; the inner loop is a flow loop, which adjusts the frequency of the heat transfer oil circulation pump (25–45Hz) and the opening of the reforming air regulating valve (0–100%) according to the target return temperature. When the thermocouple reading is <170°C, the PLC prioritizes increasing the pump frequency (+2Hz / 10s) to enhance heat exchange in the evaporation unit. If the reading is still too low after 10s, the air valve opening is simultaneously increased by 5% to enhance the exothermic reaction of the reforming reaction. When the reading is >182°C, the pump frequency is preferentially reduced. (2Hz / 10s) and activate the cooling branch; if the temperature continues to exceed the limit, reduce the air valve opening by 3%. This strategy ensures that the standard deviation of the anode inlet gas temperature σ is <0.8°C (data from 2 hours of continuous operation), and the temperature recovery time is <25s when the stack load changes abruptly (1→3kW). This implementation ensures that the HT-PEMFC always operates in the optimal hydration state and electrochemical activity window, resulting in single-cell voltage fluctuation <15mV and voltage decay rate <0.8% / 100h after 500h durability testing.

[0049] In existing technologies, the system shutdown process lacks an orderly material removal sequence and waste heat management mechanism, which can easily lead to local overheating and coking of heat transfer oil, hydrothermal aging of catalysts, and the risk of explosion due to the accumulation of flammable gases. To ensure shutdown safety and equipment lifespan, a standardized step-by-step unloading and cooling process needs to be developed.

[0050] Preferably, the system further includes a shutdown control module configured to perform the following safe shutdown operations: sequentially reducing the reforming feedstock supply, stack load power, and cathode air flow rate to zero; maintaining heat transfer oil circulation during the above process; and activating the cooler when the heat transfer oil temperature is above 100°C until the shell temperatures of the evaporation unit, reforming unit, power generation unit, and combustion unit are all ≤100°C.

[0051] The shutdown control module is implemented by a PLC program: First, the methanol / water metering pump flow rate is linearly reduced at a rate of 0.5 kg / h / min (from the rated 1.2 kg / h to 0), simultaneously reducing the fuel cell stack DC load at a rate of 100 W / min (from 5 kW to 0), taking 10 minutes; Second, the flow rate is reduced at a rate of 20 Nm... 3 The cathode air flow rate is reduced by a rate of / h / min (from the rated 120Nm). 3 The flow rate drops to 0 ( / h), taking 6 minutes; Third, maintain the heat transfer oil circulation pump running at 20Hz. When the PT100 sensor detects that the heat transfer oil outlet temperature is >100°C, automatically open the cooling branch (three-way valve opening 50%), and adjust the cooling water flow rate to 1.5m³ / h.3 / h; Fourth step, when the readings of all thermocouples on the surface of the unit housing (a total of 8 points, distributed in the upper middle part of each equipment housing) are ≤100°C and remain so for 5 minutes, the PLC issues a pump stop command and closes all valves. This process allows the highest temperature point of the heat transfer oil (the outlet of the burner heat exchange chamber) to be steadily reduced from 315°C to 95°C, with no local overheating (>320°C) or coking phenomena throughout the process; after 100 start-stop cycles, the reforming catalyst retains an activity rate of >96.5% (based on methanol conversion rate at 250°C); no deflagration events were recorded in the system. This implementation method comprehensively avoids the risks of thermal stress damage, chemical aging, and safety accidents during shutdown, significantly extending the system's entire life cycle.

[0052] In existing technologies, the mixture of residual air on the cathode side and residual combustible gas on the anode side at the end of shutdown may form an explosive atmosphere. Relying solely on natural purging is time-consuming and its effectiveness is uncontrollable. To improve the safety margin for applications in confined spaces, active inerting or enhanced purging mechanisms need to be introduced.

[0053] Preferably, the shutdown control module is further configured to: when the cathode air flow rate drops to below 30% of the rated flow rate, purge the combustion chamber of the combustion unit with nitrogen or excess air for no less than 60 seconds to remove residual combustible gases and reduce the risk of deflagration.

[0054] When the cathode air flow sensor reading is <36 Nm 3 / h (rated 120Nm) 3 When the nitrogen concentration reaches 30% (per hour), the PLC immediately opens the nitrogen purging valve (model: Bürkert Type 290) at a rate of 0.8 Nm. 3 High-purity nitrogen (99.999% purity) is introduced into the combustion chamber at a flow rate of / h for 65s. The nitrogen is injected through the central hole of the flame stabilizer at the front of the combustion chamber, pushing residual gas axially through the flue and out. After purging, the nitrogen valve is closed, and the heat transfer oil cooling process is initiated. This measure reduces the concentration of combustible gas (LEL) in the combustion chamber from 12% to <0.5% within 30s, far below the lower explosive limit of methanol (LEL=6%). In confined environments such as ship cabins, this design has passed ATEX II 2G Ex db IIB T4 Gb explosion-proof certification. In practical applications, compressed air can also be used as the purging gas (flow rate increased to 1.2 Nm³ / h). 3 The purging time can be extended to 90 seconds ( / h), but this embodiment does not limit it. This implementation provides deterministic explosion-proof protection for high-safety-level application scenarios, greatly expanding the applicability of this system.

[0055] In existing technologies, high-temperature proton exchange membrane fuel cells (HT-PEMFCs) generally employ a PBI / phosphoric acid system. However, the specific doping ratio, membrane thickness, and CO tolerance threshold lack targeted optimization, affecting the overall system efficiency and robustness. To fully leverage the technological advantages of HT-PEMFC in this system, its core membrane material needs to be engineered and customized.

[0056] Preferably, the power generation unit is a high-temperature proton exchange membrane fuel cell stack, wherein the proton exchange membrane is a composite membrane of polybenzimidazole (PBI) matrix doped with 85–95 wt% phosphoric acid, the operating temperature is 160–180°C, and it is resistant to carbon monoxide with a volume concentration ≤3%.

[0057] The proton exchange membrane was prepared by solution casting: PBI powder (weight average molecular weight 65,000) was dissolved in concentrated phosphoric acid (85 wt%), stirred at 160°C for 6 h to form a homogeneous solution, poured onto a glass plate, and vacuum dried at 120°C for 12 h. A PBI / phosphoric acid composite membrane with a thickness of 35 ± 2 μm was obtained by peeling. The membrane was then hot-pressed onto carbon paper (Toray TGP-H-060) to prepare a membrane assembly (MEA). The hot-pressing temperature was 140°C, the pressure was 3 MPa, and the holding time was 10 min. The stack was tested at 170°C, atmospheric pressure, H2 / air (stoichiometric ratio 1.4 / 2.2), and 30% humidity. The open-circuit voltage was 0.98 V, and the peak power density was 0.62 W / cm³. 2 When the CO concentration in the anode gas rises to 3%, the voltage decay is <5% (compared to the CO-free condition), confirming its excellent CO tolerance. The membrane exhibits a proton conductivity >0.12 S / cm at 180°C and a phosphoric acid loss rate <0.8 wt% / 100h (800h accelerated aging test). In practical applications, the membrane thickness can be selected as 30 μm or 40 μm, and the phosphoric acid doping rate can be 88 wt% or 92 wt%, which are not limited in this embodiment. This implementation enables the fuel cell stack to achieve high-stability output in the CO-containing reforming gas atmosphere unique to this system, avoiding the need for additional CO preferential oxidation (PROX) or methanation units, simplifying the system structure and improving overall energy efficiency.

[0058] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A self-heating high-temperature methanol fuel cell system, comprising an evaporation unit, a reforming unit, a power generation unit, and a combustion unit connected by pipelines, wherein the system is configured with a heat transfer oil circulation loop to achieve thermal coupling between the units; characterized in that, The heat transfer oil circulation loop is a closed-loop structure, using high-temperature resistant organic heat transfer oil as the heat exchange medium. It flows through the combustion unit, evaporation unit and power generation unit in sequence and then returns to the combustion unit, forming a full-process temperature zone stepped heat exchange path. The fuel inlet of the combustion unit is connected to the anode exhaust gas outlet of the power generation unit and is configured to continuously burn the anode exhaust gas as the main fuel. The heat generated is transferred to the evaporation unit via heat transfer oil for the vaporization of methanol aqueous solution, and to the power generation unit to maintain its operating temperature. The reaction temperature of the reforming unit is also regulated by the waste heat feedback of the heat transfer oil. The system is also equipped with a heat transfer oil temperature active control module, including a cooler and a controlled three-way valve. The cooler is located in the heat transfer oil circuit bypass and exchanges heat with the external cooling medium. The three-way valve is configured to dynamically adjust the flow rate of heat transfer oil flowing into the cooler in order to coordinate with the heat output of the combustion unit, so that the outlet steam temperature of the evaporation unit, the inlet reaction gas temperature of the reforming unit, and the anode inlet gas temperature of the power generation unit are stabilized in their respective optimal reaction temperature zones. The reforming unit has a tubular structure, with its catalytic bed filled with a pre-reduced copper-based composite oxide catalyst. The arrangement of the tubular components meets the requirements for enhanced radial heat transfer, thereby suppressing hot spots in the bed and ensuring that the methanol autothermal reforming reaction proceeds stably at 220-280℃.

2. The self-heating high-temperature methanol fuel cell system according to claim 1, characterized in that, The heat transfer oil circulation loop is equipped with a heat transfer oil circulation pump, and the working temperature range of the high-temperature resistant organic heat transfer oil is 150-320℃.

3. The self-heating high-temperature methanol fuel cell system according to claim 2, characterized in that, The cooler is a water-cooled plate heat exchanger, and its cooling water circuit is equipped with a flow regulating valve and a temperature sensor. The temperature sensor is used to monitor the outlet temperature of the heat transfer oil in real time and feed the signal back to the control system to dynamically adjust the opening of the three-way valve.

4. The self-heating high-temperature methanol fuel cell system according to claim 1, characterized in that, The combustion unit includes an ignition chamber and a heat exchange chamber; The ignition chamber is equipped with a methanol atomizing nozzle, a flame stabilizer and a high-pressure ignition needle, and the ignition chamber has a first fuel inlet, which is connected to a fresh methanol supply source through a pipeline. The heat exchange chamber has a second fuel inlet, which is connected to the anode exhaust gas outlet of the power generation unit; Preferably, the heat exchange cavity is provided with multiple rows of longitudinally arranged metal fins, and the surface of the fins is treated with an Al2O3 or SiC ceramic coating. The heat transfer oil flows in a serpentine flow pattern within the heat exchange chamber, with an elliptical cross-section and a major axis perpendicular to the main flue gas direction.

5. The self-heating high-temperature methanol fuel cell system according to claim 1, characterized in that, The reforming unit is a detachable tubular reactor with an inner diameter of 15-25 mm, a wall thickness of 1.0-2.0 mm, and the tube material is 316L austenitic stainless steel or 310S austenitic heat-resistant stainless steel.

6. The self-heating high-temperature methanol fuel cell system according to claim 5, characterized in that, The catalyst particles in the reforming unit have a diameter of 3-5 mm, the center-to-center distance between adjacent tubes is 8-20 mm, and the ratio of the center-to-center distance to the particle diameter is 2.5-4.

5.

7. The self-heating high-temperature methanol fuel cell system according to claim 1, characterized in that, The system is configured to operate sequentially in the preheating start-up phase, low-power operation phase, self-heating balance phase, and load increase phase. During the preheating and start-up phase, the combustion unit consumes fresh methanol only through the first fuel inlet for ignition and heating. When the temperature of the heat transfer oil rises to ≥160℃, the system preheating ends. In the low-power stage, methanol is introduced into the evaporation unit for vaporization and mixing with air. The methanol oxidation reaction in the reforming unit heats the reformer and generates hydrogen-rich gas to drive the fuel cell stack unit into a low-power output state. The control system opens the second fuel inlet and simultaneously reduces the supply of fresh methanol, relying on exhaust gas combustion to maintain the system's thermal balance.

8. The self-heating high-temperature methanol fuel cell system according to claim 7, characterized in that, During the self-heating equilibrium stage, the control system is configured to coordinately adjust the reforming air flow rate, the speed of the heat transfer oil circulation pump, and the opening of the three-way valve of the cooler based on the feedback signals from the anode inlet gas temperature sensor of the power generation unit and the temperature sensor of the reforming unit, so that the bed temperature of the reforming unit is stably maintained at 220-280℃ and the anode inlet gas temperature is stably maintained at 170-182℃.

9. The self-heating high-temperature methanol fuel cell system according to claim 1, characterized in that, The system also includes a shutdown control module configured to perform the following safe shutdown operations: The reforming feedstock supply, stack load power, and cathode air flow are linearly reduced to zero in sequence; the heat transfer oil circulation is maintained during the above process, and the cooler is activated when the heat transfer oil temperature is higher than 100°C, until the shell temperatures of the evaporation unit, reforming unit, power generation unit, and combustion unit are all ≤100°C. Preferably, the shutdown control module is further configured to: When the cathode air flow rate drops to less than 30% of the rated flow rate, nitrogen or excess air is introduced into the combustion chamber of the combustion unit for purging for no less than 60 seconds to remove residual combustible gases and reduce the risk of deflagration.

10. The self-heating high-temperature methanol fuel cell system according to claim 1, characterized in that, The power generation unit is a high-temperature proton exchange membrane fuel cell stack. Its proton exchange membrane is a composite membrane of polybenzimidazole matrix doped with 85-95 wt% phosphoric acid. The operating temperature is 160-180℃, and it is resistant to carbon monoxide with a volume concentration of ≤3%.

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