Anion exchange membrane electrolyzer integrated with step phase change temperature control and heat management method

Abstract

The application discloses an integrated stepwise phase change temperature control anion exchange membrane electrolyzer and a heat management method, and belongs to the technical field of hydrogen production by water electrolysis. The application is aimed at the demand of the AEM electrolyzer 45-85 DEG C exclusive temperature zone, and a three-stage phase change temperature shaped alkali-resistant composite phase change unit is integrated in the inner side of the heat production area of the electrolyzer, the temperature of the unit is increased in turn, direct heat exchange is realized through surface contact heat coupling, all working conditions such as cold start heat preservation, rated constant temperature, overload protection and shutdown heat preservation can be covered, the rated working condition temperature fluctuation is controlled within ± 3 DEG C, and the limit temperature is limited within the 85 DEG C safety threshold; the control logic of the matched passive priority and active cooperation can suppress the temperature oscillation caused by fluctuating load. The electrolyzer has fast heat response and good alkali resistance compatibility, can effectively improve the operation stability and system energy efficiency of the AEM electrolyzer, and is suitable for off-grid renewable energy hydrogen production scene.

Description

Technical Field

[0001] This invention relates to the field of water electrolysis for hydrogen production, and in particular to an anion exchange membrane electrolyzer with integrated stepped phase change temperature control and a thermal management method. Background Technology

[0002] Anion exchange membrane (AEM) electrolysis for hydrogen production combines the low cost of alkaline electrolyzers with the high efficiency and compactness of PEM electrolyzers, making it a significant development direction for green hydrogen technology. The optimal operating temperature for AEM electrolyzers is concentrated between 60 and 70°C, with the extreme operating temperature typically not exceeding 85°C. Temperatures that are too low will lead to increased membrane resistance and decreased electrolysis efficiency, while temperatures that are too high will accelerate the chemical degradation of the anion exchange membrane, catalyst deactivation, and aging of seals, significantly shortening equipment lifespan.

[0003] In off-grid photovoltaic / wind power hydrogen production scenarios, the output power of renewable energy is highly volatile, which leads to frequent changes in the heat generation rate of the electrolyzer and large fluctuations in the stack temperature, making it difficult to maintain it stably within the optimal efficiency range. At the same time, the stack cools down rapidly at night or during shutdown, and a large amount of electrical energy is required for preheating during cold start the next day, resulting in low overall system energy efficiency.

[0004] Existing thermal management solutions for electrolyzers mostly employ active cooling (such as liquid cooling pipes), which consumes a large amount of energy, and the heat released during electrolysis is not effectively utilized. Phase change materials (PCMs) achieve constant-temperature thermal storage through the latent heat of solid-liquid phase change, and have the characteristics of being power-free and having high energy density. They have been attempted to be applied to the temperature control of electrolyzers.

[0005] Current phase change temperature control solutions have the following main shortcomings: 1. It is designed primarily for alkaline electrolytic cells or PEM electrolytic cells, but is not compatible with the dedicated temperature range of 45~85℃ and weakly alkaline internal environment of AEM electrolytic cells, resulting in insufficient alkali resistance and compatibility of the materials. 2. The phase change material used can only achieve narrow temperature control and cannot simultaneously cover the full range of operating conditions, including cold start insulation, rated constant temperature, and over-temperature protection. 3. Most of them are external heat storage devices, which indirectly exchange heat through the electrolyte circuit. They have slow thermal response speed, high contact thermal resistance, and cannot directly control the temperature of the electrode reaction zone.

[0006] Therefore, developing a multi-temperature zone phase change structure that is adapted to the specific temperature zone of the AEM electrolyzer, directly integrated into the fuel cell stack, and capable of passive temperature control under all operating conditions is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] This invention provides an anion exchange membrane electrolyzer with integrated stepped phase change temperature control and a thermal management method to overcome the above-mentioned problems.

[0008] To achieve the above objectives, the technical solution of the present invention is as follows: The present invention provides an anion exchange membrane electrolyzer with integrated stepped phase change temperature control, comprising an electrolyzer body and a stepped phase change module disposed within the electrolyzer body; The stepped phase change module includes a first phase change unit, a second phase change unit, and a third phase change unit located on one side of the heat generation area of ​​the electrolytic cell body. The first phase change unit, the second phase change unit, and the third phase change unit are arranged sequentially along the heat conduction direction from low to high phase change temperature. The phase transition peak temperature of the first phase transition unit is 45-55℃; the phase transition peak temperature of the second phase transition unit is 60-70℃; and the phase transition peak temperature of the third phase transition unit is 70-80℃. The first phase change unit, the second phase change unit, and the third phase change unit all include a sealed metal shell and a phase change material disposed within the sealed metal shell.

[0009] Furthermore, the phase change materials are all composed of a mixture of n-alkanes and porous expanded graphite, and the mass ratio of the n-alkane mixture to the expanded graphite is 80:20-85:15.

[0010] Further, the n-alkane mixture of the first phase change unit is a mixture of n-docosane and n-pentane in a mass ratio of 7:3-3:7; the n-alkane mixture of the second phase change unit is a mixture of n-hexadecane and n-triane in a mass ratio of 7:3-1:9; and the n-alkane mixture of the third phase change unit is a mixture of n-dodecane and n-hexadecane in a mass ratio of 6:4-2:8.

[0011] Furthermore, the expansion volume of the porous expanded graphite is 200-400 mL / g, and the thermal conductivity of the phase change material is 2 W / (m·K).

[0012] Furthermore, when the electrolytic cell is a laboratory fixture with thick electrode plates, the electrolytic cell body is a thick electrode plate; multiple thick electrode plates are stacked, and a membrane electrode assembly is provided between two thick electrode plates; a fluid flow channel is provided on one side of the thick electrode plate, and an installation groove for installing a first phase change unit, a second phase change unit, and a third phase change unit is opened on the inner wall of the side of the thick electrode plate that is in close contact with the fluid flow channel; the first phase change unit is in close contact with the inner wall of the heat generation area of ​​the electrolytic cell body; the direction from the heat generation area to the opening of the electrolytic cell body is the heat conduction direction; the first phase change unit, the second phase change unit, and the third phase change unit are arranged sequentially and spaced apart from the heat generation area on the electrolytic cell body to the opening of the electrolytic cell body, respectively forming a low-temperature phase change heat storage area, a medium-temperature phase change heat storage area, and a high-temperature phase change heat storage area; the opening of the electrolytic cell body is sealed by a metal cover plate.

[0013] Furthermore, when the electrolytic cell is an industrial stack made of bipolar plates, the electrolytic cell body includes a plurality of single cells stacked in sequence and end plates disposed at both ends of the single cells. The second phase change unit and the third phase change unit are respectively inserted between two adjacent single cells, and the third phase change unit is located in the middle of the electrolytic cell body. The second phase change unit is located on both sides of the third phase change unit, and the first phase change unit is located in the mounting cavity on the end plate.

[0014] Furthermore, a metal mesh thermally conductive support layer is provided inside the sealed metal shell. The metal mesh thermally conductive support layer is fixed to the inner wall of the sealed metal shell and forms a thermally conductive connection with the sealed metal shell. The phase change material is filled in the mesh of the metal mesh thermally conductive support layer and around the metal mesh thermally conductive support layer.

[0015] Another aspect of the present invention provides a thermal management method for an anion exchange membrane electrolyzer with integrated stepped phase change temperature control, comprising the following steps: S1 Cold Start Stage: The anion exchange membrane electrolyzer with integrated stepped phase change temperature control starts from room temperature. The first phase change unit releases the latent heat of solidification to preheat the electrolyzer to above 45°C, shortening the time for the electrolyzer to reach the working temperature. S2 Rated operation stage: The electrolytic cell enters the working temperature of 60~70℃. The second phase change unit continuously absorbs the heat generated by electrolysis through the latent heat of melting, and stabilizes the temperature of the electrolytic cell within the phase change range with a fluctuation range of ≤±3℃. S3 Overload Protection Stage: When the current density increases or the ambient temperature rises and the electrolytic cell temperature exceeds 65°C, after the second phase change unit is saturated with heat storage, the third phase change unit starts melting and absorbing heat to slow down the heating rate and limit the maximum temperature of the electrolytic cell to within 85°C. S4 Shutdown and Heat Preservation Stage: After the electrolytic cell is shut down, the three layers of phase change materials solidify and release heat in sequence to maintain the temperature of the electrolytic cell and achieve a hot standby state.

[0016] Furthermore, when the anion exchange membrane electrolyzer with integrated cascade phase change temperature control is connected to a fluctuating renewable energy power supply, during the rated operation phase S2 and the overload protection phase S3, the phase change material absorbs and stores heat when the load increases, and releases and replenishes heat when the load decreases, thereby achieving a gradual decrease in the temperature of the electrolyzer.

[0017] Furthermore, following the S3 overload protection phase, a control step prioritizing passive actions and coordinating active actions is also included: When the temperature of the electrolytic cell is detected to be <85℃, the external active cooling device remains closed, and passive temperature control is achieved by relying on the cascade phase change material. When the temperature of the electrolytic cell is ≥85℃ and the third phase change unit has completely melted, the external active cooling device is activated to cause the phase change material to re-solidify in order to restore its heat storage capacity. If the electrolytic cell temperature continues to rise after the external active cooling is started, the electrolytic cell operating current will be reduced or the shutdown protection will be triggered.

[0018] The beneficial effects of this invention are: 1. The electrolytic cell of this invention has a built-in stepped phase change module. Through the phase change units with different phase change temperatures, it is adapted to the exclusive temperature range of 45~85℃ and the weakly alkaline internal environment of the AEM electrolytic cell. It matches the alkali-resistant compatibility of the AEM electrolytic cell material and realizes passive temperature control of the electrolytic cell under all working conditions from cold start, rated operation to overload protection. It effectively covers the temperature control requirements of cold start insulation, rated constant temperature, and over-temperature protection under all working conditions, avoids the problem of lag in response of traditional active cooling, and is fully adapted to the operating conditions of AEM electrolytic cells.

[0019] 2. This invention, by employing a three-stage phase change material, provides seamless passive thermal management for the AEM electrolyzer across the entire temperature range from 45°C cold start to 85°C extreme operating conditions. It possesses wide-range temperature control capabilities, overcoming the inherent limitations of single-stage phase change materials, such as narrow temperature control windows and rigid response. Because the three-stage phase change materials simultaneously absorb and release heat in the low, medium, and high temperature zones, the thermal buffer time is extended. Therefore, under the same heat generation conditions, the temperature control time of this invention is superior to that of a single-stage phase change solution.

[0020] 3. This invention employs a built-in phase change energy storage structure, utilizing the internal space of the electrolytic cell end plate to add phase change energy storage. It eliminates the need for traditional external heat storage devices and indirect heat exchange via the electrolyte circuit, enabling direct and precise temperature control of the electrode reaction zone, significantly improving thermal response speed and reducing contact thermal resistance. Simultaneously, its compact structure fully utilizes waste heat, improving energy efficiency, and eliminates the need for additional complex piping, reducing system cost and failure rate. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a block diagram of the electrolytic cell thermal management system of the present invention; Figure 2 This is a schematic cross-sectional view of the small electrolytic cell of the present invention; Figure 3 This is a schematic cross-sectional view of the large fuel cell stack of the present invention (single-layer fuel cell stack phase change unit). Figure 4 This is a schematic cross-sectional view of the large fuel cell stack (multilayer fuel cell stack phase change unit) of the present invention.

[0023] In the picture: 1. Electrolytic cell body; 2. Membrane electrode assembly; 3. First phase change unit; 4. Second phase change unit; 5. Third phase change unit; 6. Metal cover plate; 7. Single cell; 8. End plate; 9. Bipolar plate; 10. Insulating plate; 11. Mounting slot. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1 An anion exchange membrane electrolyzer with integrated stepped phase change temperature control includes an electrolyzer body 1 and a stepped phase change module disposed within the electrolyzer body 1. The stepped phase change module includes a first phase change unit 3, a second phase change unit 4, and a third phase change unit 5 located on one side of the heat generation area of ​​the electrolytic cell body. The first phase change unit 3, the second phase change unit 4, and the third phase change unit 5 are arranged sequentially along the heat conduction direction from low to high phase change temperature. The phase transition peak temperature of the first phase transition unit 3 is 45-55℃; the phase transition peak temperature of the second phase transition unit 4 is 60-70℃; and the phase transition peak temperature of the third phase transition unit 5 is 70-80℃. The first phase change unit 3, the second phase change unit 4, and the third phase change unit 5 each include a sealed metal shell and a phase change material disposed within the sealed metal shell.

[0026] The first phase change unit has a phase change peak temperature designed in the range of 45-55℃. It is used for electrolytic cell startup and low-load conditions, absorbing heat to prevent the temperature from rising too quickly and allowing the electrolytic cell to enter the high-efficiency operating range as soon as possible. The second phase change unit has a phase change peak temperature designed in the range of 60-70℃. It is used for normal full-load operation and serves as the main thermal buffer, absorbing the fluctuations in normal heat generation and stabilizing the electrolytic cell temperature within the optimal operating range. The third phase change unit has a phase change peak temperature designed in the range of 70-80℃. It serves as the last line of thermal protection in extreme conditions or when the control is abnormal. It absorbs a large amount of heat when the temperature approaches the upper limit of the electrolytic cell, buying time for active protection.

[0027] This solution features a built-in stepped phase change module designed for the AEM electrolyzer's exclusive temperature range of 40~85℃ and its weakly alkaline internal environment. The three phase change units are arranged sequentially along the heat conduction direction, from lowest to highest phase change temperature. This allows for relay-style latent heat storage under all operating conditions, including cold start insulation, rated constant temperature, and over-temperature protection, achieving continuous passive temperature control over a wide temperature range. The first phase change unit forms a surface contact thermal coupling with the heat-generating area of ​​the electrolyzer through a sealed metal shell. This eliminates the need for indirect heat exchange via the electrolyte circuit, resulting in a short heat conduction path, low contact thermal resistance, and fast thermal response. It enables precise temperature control of the electrode reaction zone, fully adapting to the operating characteristics of the AEM electrolyzer.

[0028] In specific embodiments, the phase change materials are all composed of a mixture of n-alkanes and porous expanded graphite (EG), with a mass ratio of n-alkane mixture to expanded graphite of 80:20-85:15, forming a macroscopically non-flowing, microscopically highly thermally conductive shaped bulk (phase change material). Using a shaped phase change material composed of n-alkane mixture and porous expanded graphite at a mass ratio of 80:20-85:15 allows the porous capillary structure of expanded graphite to firmly adsorb molten alkanes, fundamentally preventing phase change material leakage. Simultaneously, expanded graphite forms a continuous thermally conductive network, significantly improving the overall thermal conductivity of the phase change material, ensuring rapid heat transfer to the interior of the phase change material, avoiding the inefficient problem of surface melting only. This ratio also imparts sufficient mechanical strength to the phase change bulk, enabling it to withstand the assembly pressure of the fuel cell stack; furthermore, n-alkane is chemically inert and exhibits excellent alkali resistance and compatibility in weakly alkaline environments, making it inherently safe and reliable.

[0029] In a specific embodiment, the expansion volume of the porous expanded graphite is 200-400 mL / g, and the thermal conductivity of the phase change material is 2 W / (m·K). Using porous expanded graphite with an expansion volume of 200-400 mL / g provides sufficient pore adsorption capacity, enabling the secure locking of liquid alkanes and further enhancing the shape-stabilizing and leak-proof effect. Ultimately, the internal thermal conductivity path of the composite phase change material is unobstructed, allowing heat to diffuse rapidly within the material, improving the heat storage and release response rate, and ensuring timely temperature control and temperature uniformity. In this embodiment, the expansion volume of the porous expanded graphite is 250 mL / g.

[0030] In a specific embodiment, the n-alkane mixture of the first phase change unit 3 is a mixture of n-docosane and n-pentane in a mass ratio of 7:3-3:7; the n-alkane mixture of the second phase change unit 4 is a mixture of n-hexadecane and n-triane in a mass ratio of 7:3-1:9; and the n-alkane mixture of the third phase change unit 5 is a mixture of n-dodecane and n-hexadecane in a mass ratio of 6:4-2:8.

[0031] By precisely blending n-alkanes with different carbon numbers, the peak temperatures of the three-stage phase change units are precisely controlled to the ranges of 45-55℃, 60-70℃, and 70-80℃ using the eutectic effect. These temperatures are then matched sequentially with the cold start-up preheating temperature zone, the rated optimal operating temperature zone, and the over-temperature protection safety temperature zone of the AEM electrolyzer. The homologous compound blend exhibits excellent thermodynamic compatibility, eliminating the risk of component segregation and phase separation. Its stable latent heat of phase change ensures that the three-stage phase change materials can stably perform their heat storage and release functions within their respective temperature zones, achieving seamless temperature control across the entire temperature range and forming a synergistic system of low-temperature preheating, medium-temperature stabilization, and high-temperature protection.

[0032] In this embodiment, the phase change materials of the first phase change unit 3, the second phase change unit 4, and the third phase change unit 5 all adopt a long-chain n-alkane binary blend system, and the specific formulations are as follows: The phase change material of the first phase change unit 3 is a mixture of n-dodecane and n-pentane at a mass ratio of 4:6. The measured peak phase change temperature is 49.8℃ and the latent heat of phase change is 224J / g, which corresponds to the rated optimal operating temperature range of the AEM electrolyzer. Under steady-state operation, it absorbs the heat generated by electrolysis and maintains the constant temperature of the stack. The phase change material of the second phase change unit 4 is a mixture of n-hexadecane and n-triane in a mass ratio of 5:5. The measured peak phase change temperature is 61.2℃ and the latent heat of phase change is 218J / g, which corresponds to the medium-high load buffer temperature control range. It takes over the heat storage margin of the first phase change unit and delays the temperature rise. The phase change material of the third phase change unit 5 is a mixture of n-dodecane and n-hexadecane at a mass ratio of 4:6. The measured peak phase change temperature is 73.0℃ and the latent heat of phase change is 215J / g, which corresponds to the overload high temperature protection range. As the last heat absorption barrier, it suppresses the stack temperature from exceeding the 85℃ safety threshold.

[0033] Each phase change material is a homologous blend system with excellent thermodynamic compatibility and no risk of phase separation or component segregation. On this basis, a pure nickel mesh thermally conductive support layer is further set inside each phase change unit. This support layer forms a continuous thermally conductive path with the sealed metal shell, which increases the overall thermal conductivity of the phase change unit to 2.3 W / (m·K).

[0034] like Figure 2 , Figure 3 As shown, considering the fundamental differences in electrode thickness and assembly pressure between laboratory-scale small electrolyzer fixtures and industrial-grade large electrolyzers, the anion exchange membrane electrolyzer with integrated stepped phase change temperature control described in this embodiment includes two types, among which... Figure 2 This is a cross-sectional view of a small laboratory fixture. Figure 3 This is a schematic cross-sectional view of a large industrial fuel cell stack.

[0035] When the electrolytic cell is a small laboratory fixture: the electrolytic cell body 1 is a thick electrode plate, which is integrally milled from pure nickel metal. Multiple thick electrode plates are stacked, and a membrane electrode assembly 2 is provided between two thick electrode plates. A fluid flow channel is provided on one side of the thick electrode plate, and a mounting groove 11 is opened on the inner wall of the side of the thick electrode plate that is close to the fluid flow channel. In the mounting groove 11, the first phase change unit 3, the second phase change unit 4, and the third phase change unit 5 are stacked in sequence from the reaction side close to the membrane electrode towards the opening of the electrolytic cell body 1. The opening of the electrolytic cell body is sealed by laser welding of a metal cover plate 6 of the same material. The first phase change unit, the second phase change unit, and the third phase change unit are arranged sequentially and at intervals from the heat generation area on the electrolytic cell body to the opening of the electrolytic cell body, forming a low-temperature phase change heat storage area, a medium-temperature phase change heat storage area, and a high-temperature phase change heat storage area, respectively. That is, the first phase change unit 3 is close to the inner wall of the heat generation area of ​​the electrolytic cell body (near the side of the membrane electrode assembly 2) to form a low-temperature phase change heat storage area, the second phase change unit 4 is in the middle to form a medium-temperature phase change heat storage area, and the third phase change unit 5 is located on the outermost side to form a high-temperature phase change heat storage area. Heat is conducted outward from the heat generation area, passing through the first phase change unit, the second phase change unit, and the third phase change unit in sequence.

[0036] For laboratory applications with small clamps for thick electrode plates, the electrolytic cell is designed as a small laboratory clamp. A three-stage phase change unit is integrated into the mounting groove directly machined on the back of the fluid flow channel, resulting in a compact structure that requires no additional external space. The three-stage phase change units are arranged sequentially along the heat conduction direction from the heat-generating zone outwards, matching the fluid's temperature rise along the flow path, enabling ordered, stepped heat absorption and improving heat exchange efficiency. A welded metal cover seal ensures the sealing and alkali corrosion resistance of the phase change units, meeting the assembly and operation requirements of laboratory electrolytic cells. This arrangement of the three-stage phase change units ensures that the fluid temperature always encounters an endothermic phase change material with a matching temperature as it rises along the flow path, thus achieving efficient and ordered stepped heat absorption.

[0037] When the electrolytic cell is an industrial stack composed of numerous thin electrode plates, since the thin plates cannot be slotted and the stack requires several tons of assembly pressure, this application adopts an independent insertion phase change unit structure. This phase change unit is an independent component that does not participate in the electrochemical reaction but is specifically designed for thermal management, selectively inserted between two adjacent single cells (e.g., one unit inserted every 3-5 single cells). The electrolytic cell structure is as follows: the electrolytic cell body 1 includes multiple single cells 7 stacked sequentially and end plates 8 located at both ends of the single cells; each single cell 7 consists of bipolar plates 9 and membrane electrode assemblies 2, with an insulating plate 10 between the bipolar plates 9 and the end plates 8; the ends of the single cells 7 are pressed and fixed by the end plates 8 and the insulating plate 10. An mounting cavity is machined on the end plate 8, and the first phase change unit 3 is located within the mounting cavity on the end plate 8. The third phase change unit 5 is located in the middle of the stack, and multiple sets of the third phase change unit 5 can be provided. Figure 4The stack consists of a second phase change unit 4 and a first phase change unit 3 inserted between adjacent cells. The first phase change unit 3 is located on the end plate 8 (i.e., the outermost low-temperature zone), and the second phase change unit 4 is located on both sides of the third phase change unit 5. The sealed metal shell of each phase change unit is laser-welded from 316L, Hastelloy, or pure nickel panels, with a total thickness of 3-5 mm. The end plate 8 of the stack is made of pure nickel metal, and the insulating plate 10 is made of polytetrafluoroethylene.

[0038] All phase change materials are permanently encapsulated within a metal casing that is completely physically isolated from the electrolyte. The metal casing is preferably made of 316L stainless steel, but pure nickel or Hastelloy alloys are also acceptable. All openings and seams are laser-welded to create an airtight seal. After welding, the casing can be internally evacuated or filled with inert gas. This encapsulation structure ensures that the material can withstand prolonged immersion in 1M KOH at 85°C electrolyte for over 10,000 hours without any corrosion or leakage. The outer surface of the metal casing can also be optionally coated with an alkali-resistant insulating coating, or isolated from adjacent components with potential differences via PTFE gaskets, completely eliminating the risk of electrochemical corrosion.

[0039] In this embodiment, the sealed metal shells of each phase change unit in the large industrial fuel cell stack and the small laboratory fixture are made of pure nickel. The sealed metal shells absorb heat from adjacent membrane electrodes and plates through large-area contact, resulting in a very short heat conduction path and high temperature control efficiency. A metal mesh thermally conductive support layer is provided inside the sealed metal shell to improve compressive strength and is fixed to the inner wall of the cavity by vacuum brazing. The metal mesh thermally conductive support layer is a pure nickel mesh support layer. This metal mesh thermally conductive support layer constitutes an auxiliary thermally conductive framework extending from the cavity wall into the interior of the shaped composite phase change material. The molten phase change material is impregnated and filled into the nickel mesh pores and around the metal mesh thermally conductive support layer under negative pressure or vacuum conditions. This operation temperature is approximately 10°C higher than the upper limit of the temperature range of each phase change unit. After cooling and shaping, no additional binder is required. A pure nickel mesh thermally conductive support layer is installed within the sealed metal casing. This serves two purposes: firstly, it forms an auxiliary thermally conductive framework extending into the phase change material (PCM), further enhancing internal thermal conductivity, reducing thermal resistance in the core region of the PCM, and improving the response speed and temperature uniformity of heat storage and release; secondly, it provides structural support for the casing, withstanding the pressure of the fuel cell assembly and preventing the PCM from being crushed and deformed. The pure nickel material possesses excellent resistance to alkali corrosion, allowing for long-term stable operation in the weakly alkaline environment of the AEM electrolytic cell, ensuring structural durability.

[0040] like Figure 1As shown in the diagram, the thermal management system of the anion exchange membrane electrolyzer with integrated cascade phase change temperature control described in this embodiment consists of an electrolyzer, a cascade phase change module, an electrolyzer parameter acquisition device, a phase change state detection device, a control device, a power supply device, a communication device, and a host monitoring system. Each device is connected through signal and power loops to realize real-time acquisition, graded control, and remote monitoring of the electrolyzer temperature and phase change state, forming a passive-first, active-coordinated full-condition temperature control system.

[0041] Based on the above electrolytic cell structure, the thermal management method provided in this embodiment can achieve passive temperature control and active-passive coordinated regulation under all operating conditions. The specific steps are as follows: S1 Cold Start Stage: The anion exchange membrane electrolyzer with integrated stepped phase change temperature control starts from room temperature. The first phase change unit releases the latent heat of solidification to preheat the electrolyzer to above 45°C, shortening the time for the electrolyzer to reach the working temperature. S2 Rated Operation Stage: The electrolytic cell enters the working temperature of 60~70℃. The second phase change unit continuously absorbs the heat generated by electrolysis through the latent heat of melting, stabilizing the temperature of the electrolytic cell within the phase change range with a fluctuation range of ≤±3℃. S3 overload protection stage: When the current density increases or the ambient temperature rises and the electrolytic cell temperature exceeds 65°C, after the second phase change unit is saturated with heat storage, the third phase change unit starts melting and absorbing heat to slow down the heating rate and limit the maximum temperature of the electrolytic cell to within 85°C. S4 Shutdown and Heat Preservation Stage: After the electrolytic cell is shut down, the three layers of phase change material solidify and release heat in sequence to maintain the temperature of the electrolytic cell and achieve a hot standby state.

[0042] A four-stage, full-condition passive temperature control method enables the three-stage phase change materials to function in a phased, orderly, and synergistic manner: During the cold start phase, the low-temperature phase change unit releases its latent heat of solidification to preheat the fuel cell stack, shortening the heating time and reducing cold start energy consumption; during the rated operation phase, the medium-temperature phase change unit continuously absorbs electrolytic heat through its latent heat of fusion, keeping temperature fluctuations within ±3℃ (≤±3℃), ensuring electrolysis efficiency and membrane element lifespan; during the overload phase, after the medium-temperature unit reaches heat storage saturation, the high-temperature phase change unit takes over by melting and absorbing heat, slowing the temperature rise rate and limiting the maximum temperature to a safe threshold of 85℃; during the shutdown phase, the three-stage phase change materials solidify and release heat sequentially, maintaining the fuel cell stack temperature for an extended period and achieving a hot standby state. Temperature control throughout the entire operating cycle can be achieved without additional power, significantly improving system energy efficiency and operational stability.

[0043] Furthermore, when the anion exchange membrane electrolyzer with integrated cascade phase change temperature control is connected to a fluctuating renewable energy power supply, during the rated operation phase S2 and the overload protection phase S3, the phase change material absorbs and stores heat when the load increases, and releases and replenishes heat when the load decreases, thereby achieving a gradual decrease in the temperature of the electrolyzer.

[0044] For fluctuating renewable energy power supply scenarios, the bidirectional characteristics of latent heat storage and release of phase change materials can be utilized. When the load increases, excess generated heat is absorbed and stored, and when the load decreases, the stored heat is released to replenish the heat. This can effectively smooth out temperature oscillations caused by power fluctuations, avoid frequent and large fluctuations in the stack temperature, maintain a relatively stable operating temperature, reduce the lifespan wear of anion exchange membranes, catalysts and seals caused by temperature alternation, and adapt to the complex operating conditions of off-grid renewable energy hydrogen production.

[0045] Furthermore, following the S3 overload protection phase, a control step prioritizing passive actions and coordinating active actions is also included: Passive priority mode: When the temperature sensor detects that the electrolytic cell temperature is <85℃, the external active cooling device remains closed, and passive temperature control is achieved by relying on the stepped phase change materials; the system operates with zero energy consumption. The heat generated is absorbed by the first, second, and third stage phase change materials as the temperature increases.

[0046] Collaborative regeneration mode: When the temperature is ≥85℃ and the third phase change unit has completely melted (indicated by temperature changes, micro-pressure changes, etc., when it is completely melted), the external active cooling device is activated to cause the phase change material to cool down and re-solidify in order to restore its heat storage capacity; this mode realizes the reversible utilization of the phase change material and extends the continuous temperature control time of the phase change system.

[0047] Safety protection mode: If the temperature continues to rise after the external active cooling is started, the electrolyzer operating current will be reduced or the shutdown protection will be triggered to suppress heat generation from the source and ensure the safe operation of the fuel cell stack.

[0048] The system employs a passive-first, active-coordinated control logic. Under normal operating conditions, it relies entirely on passive temperature control of the phase change material, resulting in zero energy consumption and improved overall energy efficiency. When the high-temperature phase change unit completely melts and the temperature control capacity approaches its limit, active cooling is initiated to re-solidify the phase change material, restore its heat storage capacity, and enable reversible recycling of the phase change material, thus extending the effective temperature control duration. Under extreme over-temperature conditions, it provides fallback protection through current reduction or shutdown, balancing the system's operational energy efficiency and safety reliability, and effectively preventing membrane degradation and equipment damage caused by extreme overheating.

[0049] Using the laboratory miniature fixture (electrolytic cell) of this embodiment as the test object, temperature control accuracy, overload protection capability and cycle stability were tested.

[0050] Performance test results: Rated current density 200mA / cm³ 2 After continuous operation for 2 hours, the core temperature of the electrolytic cell stabilized at 57.5-59.1℃, with temperature fluctuations ≤ ±0.8℃; 400mA / cm 2Under overload conditions, the electrolytic cell operates continuously for 30 minutes, with a maximum temperature of 82.4℃, which remains below the safety threshold of 85℃. After 1000 complete melting-solidification cycles, the latent heat decay rate of each phase change unit is ≤2.7%, and the pure nickel shell shows no corrosion or leakage, making it suitable for the long-term use of conventional industrial-grade AEM electrolytic cells.

[0051] Example 2 This embodiment has the same structure as the laboratory miniature fixture (electrolytic cell) in Embodiment 1, the difference being that: both the main body 1 of the electrolytic cell and the sealing cover 2 are made of Hastelloy C-276 material, which has a nickel content ≥57% and excellent resistance to alkali corrosion and high-temperature stress cracking, maintaining structural stability under long-term continuous operation conditions of high humidity and high alkali. The metal mesh thermal conductive support layer inside the sealed metal shell is replaced with an expanded graphite pressed mesh skeleton. The expanded graphite pressed mesh skeleton has a thickness of 2mm, a porosity of 82%, and an expansion volume of 250 mL / g. The expanded graphite is integrally formed and fixed to the inner cavity of the sealed metal shell through a molding process to form a graphite skeleton; the overall mass of the phase change unit is reduced by 31% compared to the scheme in Embodiment 1 where the metal mesh thermal conductive support layer uses a nickel mesh.

[0052] Simultaneously, the ratio of the three-layer phase change plate is optimized to adapt to scenarios with wide load fluctuations: First phase change unit 3: n-dodecane to n-pentane mass ratio 3:7, phase change peak temperature 51.1℃, preferentially covering the high-efficiency operating range under low load; Second phase change unit 4: n-hexadecane to n-triane mass ratio 3:7, phase change peak temperature 63.5℃, widening the medium and high temperature buffer range; The third phase change unit 4 has a mass ratio of n-dodecane to n-hexadecane of 3:7, a phase change peak temperature of 74.3℃, and enhanced high-temperature protection and heat storage capacity.

[0053] Temperature control accuracy, overload protection capability, and cycle stability were tested on the laboratory miniature fixture electrolytic cell in this embodiment.

[0054] Performance test results: After 1000 hours of accelerated aging in a saturated alkaline humid environment at 60℃, the Hastelloy shell (electrolytic cell body and sealing cover) showed no pitting or cracking, and the performance of the phase change material did not deteriorate significantly. The continuous protection time under overload conditions was increased by 18% compared to Example 1, and the peak temperature of the electrolytic cell was stably controlled within 81.9℃ with temperature fluctuation ≤ ±3℃. It is suitable for high-power industrial-grade AEM electrolysis systems with long-term continuous operation.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An anion exchange membrane electrolyzer with integrated stepped phase change temperature control, characterized in that, It includes an electrolytic cell body (1) and a stepped phase change module disposed within the electrolytic cell body (1); The stepped phase change module includes a first phase change unit (3), a second phase change unit (4) and a third phase change unit (5) located on one side of the heat generation area of ​​the electrolytic cell body, and the first phase change unit (3), the second phase change unit (4) and the third phase change unit (5) are arranged sequentially along the heat conduction direction from low to high phase change temperature. The phase transition peak temperature of the first phase transition unit (3) is 45-55℃; the phase transition peak temperature of the second phase transition unit (4) is 60-70℃; and the phase transition peak temperature of the third phase transition unit (5) is 70-80℃. The first phase change unit (3), the second phase change unit (4) and the third phase change unit (5) all include a sealed metal shell and a phase change material disposed in the sealed metal shell.

2. The anion exchange membrane electrolyzer with integrated stepped phase change temperature control according to claim 1, characterized in that, The phase change materials are all composed of a mixture of n-alkanes and porous expanded graphite, and the mass ratio of the n-alkane mixture to the expanded graphite is 80:20-85:

15.

3. The anion exchange membrane electrolyzer with integrated stepped phase change temperature control according to claim 2, characterized in that, The n-alkane mixture of the first phase change unit (3) is a mixture of n-docosahexanes and n-pentane in a mass ratio of 7:3-3:7; the n-alkane mixture of the second phase change unit (4) is a mixture of n-hexadecane and n-triane in a mass ratio of 7:3-1:9; and the n-alkane mixture of the third phase change unit (5) is a mixture of n-dodecane and n-hexadecane in a mass ratio of 6:4-2:

8.

4. The anion exchange membrane electrolyzer with integrated stepped phase change temperature control according to claim 2, characterized in that, The porous expanded graphite has an expansion volume of 200-400 mL / g, and the phase change material has a thermal conductivity of 2 W / (m·K).

5. The anion exchange membrane electrolyzer with integrated stepped phase change temperature control according to claim 1, characterized in that, When the electrolytic cell is a laboratory fixture with thick electrode plates, the electrolytic cell body (1) is a thick electrode plate; multiple thick electrode plates are stacked, and a membrane electrode assembly (2) is provided between two thick electrode plates; a fluid flow channel is provided on one side of the thick electrode plate, and an installation groove (11) for installing the first phase change unit, the second phase change unit and the third phase change unit is opened on the inner wall of the thick electrode plate that is close to the fluid flow channel. The first phase change unit is close to the inner wall of the heat generation area of ​​the electrolytic cell body; the direction from the heat generation area to the opening of the electrolytic cell body is the heat conduction direction; the first phase change unit, the second phase change unit and the third phase change unit are arranged in sequence at intervals from the heat generation area on the electrolytic cell body to the opening of the electrolytic cell body, forming a low temperature phase change heat storage area, a medium temperature phase change heat storage area and a high temperature phase change heat storage area respectively. The opening of the electrolytic cell body is sealed by a metal cover plate (6).

6. The anion exchange membrane electrolyzer with integrated stepped phase change temperature control according to claim 1, characterized in that, When the electrolytic cell is an industrial stack made of bipolar plates, the electrolytic cell body includes a plurality of single cells (7) stacked in sequence and end plates (8) disposed at both ends of the single cells. The second phase change unit (4) and the third phase change unit (5) are respectively inserted between two adjacent single cells, and the third phase change unit (5) is located in the middle of the electrolytic cell body. The second phase change unit (4) is located on both sides of the third phase change unit (5), and the first phase change unit (3) is located in the mounting cavity on the end plate (8).

7. The anion exchange membrane electrolyzer with integrated stepped phase change temperature control according to claim 1, characterized in that, The sealed metal shell has a metal mesh thermally conductive support layer inside. The metal mesh thermally conductive support layer is fixed to the inner wall of the sealed metal shell and forms a thermally conductive connection with the sealed metal shell. The phase change material fills the mesh of the metal mesh thermally conductive support layer and the area around the metal mesh thermally conductive support layer.

8. A thermal management method for an anion exchange membrane electrolyzer with integrated stepped phase change temperature control as described in any one of claims 1-7, characterized in that, Includes the following steps: S1 Cold Start Stage: The anion exchange membrane electrolyzer with integrated stepped phase change temperature control starts from room temperature. The first phase change unit releases the latent heat of solidification to preheat the electrolyzer to above 45°C, shortening the time for the electrolyzer to reach the working temperature. S2 Rated operation stage: The electrolytic cell enters the working temperature of 60~70℃. The second phase change unit continuously absorbs the heat generated by electrolysis through the latent heat of melting, and stabilizes the temperature of the electrolytic cell within the phase change range with a fluctuation range of ≤±3℃. S3 Overload Protection Stage: When the current density increases or the ambient temperature rises and the electrolytic cell temperature exceeds 65°C, after the second phase change unit is saturated with heat storage, the third phase change unit starts melting and absorbing heat to slow down the heating rate and limit the maximum temperature of the electrolytic cell to within 85°C. S4 Shutdown and Heat Preservation Stage: After the electrolytic cell is shut down, the three layers of phase change materials solidify and release heat in sequence to maintain the temperature of the electrolytic cell and achieve a hot standby state.

9. The thermal management method according to claim 8, characterized in that, When the anion exchange membrane electrolyzer with integrated cascade phase change temperature control is connected to a fluctuating renewable energy power supply, during the rated operation phase S2 and the overload protection phase S3, the phase change material absorbs and stores heat when the load increases, and releases and replenishes heat when the load decreases, thereby achieving a gradual decrease in the temperature of the electrolyzer.

10. The thermal management method according to claim 8, characterized in that, Following the S3 overload protection phase, a control step that prioritizes passive response and coordinates active response is also included: When the temperature of the electrolytic cell is detected to be <85℃, the external active cooling device remains closed, and passive temperature control is achieved by relying on the stepped phase change material. When the temperature of the electrolytic cell is ≥85℃ and the third phase change unit has completely melted, the external active cooling device is activated to cause the phase change material to re-solidify in order to restore its heat storage capacity. If the electrolytic cell temperature continues to rise after the external active cooling is started, the electrolytic cell operating current will be reduced or the shutdown protection will be triggered.

Images