A fuel cell system and a method for calculating its hydrogen-to-electricity conversion efficiency.

Abstract

This invention relates to a fuel cell system and its hydrogen-to-electricity conversion efficiency calculation method, belonging to the field of solid-state hydrogen storage and fuel cell technology. It includes: a fuel cell stack module; a solid-state hydrogen storage and supply module, comprising a fuel tank filled with aluminum trihydride material, used to produce hydrogen through the thermal decomposition of aluminum trihydride and the hydrolysis of the thermal decomposition product, elemental aluminum, with the two reactions closely coupled; a fuel tank heater is provided on the outside of the fuel tank; a heating-cooling coupling module, including a heating-cooling coupler and a shared fan; the heating-cooling coupler has a built-in heating rod used to heat the fuel cell stack to the start-up temperature during the start-up phase and to cool the fuel cell stack and the cathode exhaust gas during the stabilization phase; the shared fan is used for coordinated heat regulation; a water recovery module; and an electronic control unit. The water recovery module of this invention recovers water from the exhaust gas with a high recovery rate and high hydrogen utilization rate, and the efficiency improvement effect is quantified through full-cycle integrated calculation.

Description

Technical Field

[0001] This invention relates to the field of solid-state hydrogen storage and fuel cell technology, and more particularly to a fuel cell system and a method for calculating its hydrogen-to-electricity conversion efficiency. Background Technology

[0002] A fuel cell is a device that directly converts the chemical energy stored in a compound fuel into electrical energy through a chemical reaction. It has advantages such as high efficiency, long driving time, environmental friendliness, and low noise, and has a wide range of applications.

[0003] Currently, most fuel cell systems store hydrogen using high-pressure gaseous hydrogen storage, a relatively mature technology. However, because hydrogen is compressed to high pressure (typically 35-70 MPa), there are risks of leakage and explosion. Furthermore, high-pressure gaseous hydrogen storage has a relatively low volumetric hydrogen density, meaning that for the same storage capacity, more space is required, increasing the mass and hindering improvements in the fuel cell system's volumetric power-to-weight ratio and miniaturization.

[0004] Solid-state hydrogen storage technology has attracted attention due to its high volumetric hydrogen storage density and good safety performance. Solid-state hydrogen storage can be carried out at ambient temperature and pressure, and the storage tanks are easy to seal. In the event of a hydrogen leak, solid-state hydrogen storage typically absorbs heat during hydrogen release, thus automatically reducing the leakage rate and amount, improving the safety of the hydrogen storage device. However, the current hydrogen storage efficiency per unit weight of solid-state hydrogen storage is still relatively low, or the hydrogen release temperature of some materials is too high (e.g., the hydrogen release temperature of MgH2 is generally between 250 and 400℃), making it difficult to meet the requirements of certain application scenarios.

[0005] Meanwhile, the efficiency of fuel cell systems is generally between 40% and 60%. As the application range of fuel cells continues to expand, how to further improve the efficiency of fuel cell systems is a key issue.

[0006] Existing patent document CN120242885A discloses a hydrogen storage device and hydrogen production method based on solid-state hydrogen storage materials. It focuses on the structural design of the hydrogen storage device and the thermal coupling of hydrogen production, but does not form a complete fuel cell system. This existing technology requires external power generation equipment to utilize hydrogen energy, resulting in poor adaptability and high energy loss. Furthermore, this novel device does not disclose a specific quantitative calculation method for hydrogen-to-electricity conversion efficiency, making it impossible to assess the overall system performance. Without a suitable quantitative calculation method for hydrogen-to-electricity conversion efficiency and intelligent control, it is difficult to improve the hydrogen-to-electricity conversion efficiency of the fuel cell system. In addition, existing efficiency calculation methods for fuel cell systems based on solid-state hydrogen storage have significant flaws: the thermal decomposition of aluminum trihydride and the hydrolysis of its product aluminum occur simultaneously and jointly supply hydrogen. The proportion of hydrogen supply from these two reactions changes dynamically with operating conditions, making it difficult to accurately monitor and distinguish instantaneous flow rates. This results in real-time efficiency calculation methods failing to accurately reflect the true performance of the system. Traditional methods only focus on the instantaneous efficiency of hydrogen supply from a single thermal decomposition, ignoring the contribution of secondary hydrogen supply from hydrolysis, thus underestimating the potential of solid-state hydrogen storage systems. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a fuel cell system and a method for calculating its hydrogen-to-electricity conversion efficiency. This invention utilizes aluminum trihydride (AlH3), a high-energy-density solid hydrogen storage material capable of storing hydrogen at atmospheric pressure while releasing it at relatively low temperatures. It optimizes the thermal decomposition of metal hydrides and their coupling reaction with water in solid hydrogen storage tanks. Hydrogen is produced by the hydrolysis of elemental aluminum, a byproduct of the aluminum trihydride thermal decomposition reaction, with water. Simultaneously, the heat released from the hydrolysis reaction promotes the thermal decomposition of aluminum trihydride (AlH3), resulting in the coupled release of hydrogen through these two reactions, achieving efficient heat utilization. In the fuel cell system, hydrogen can be produced by recovering water from the fuel cell exhaust gas. A device that comprehensively utilizes the thermal decomposition of AlH3 and the hydrolysis reaction of aluminum supplies hydrogen to the fuel cell. By combining the heat absorption and release processes of various system components, thermal coupling and matching relationships are designed to construct a system water circulation system, achieving efficient hydrogen circulation and internal heat utilization, thereby improving system efficiency.

[0008] The technical means employed in this invention are as follows:

[0009] In a first aspect, the present invention discloses a fuel cell system, comprising:

[0010] The fuel cell stack module is used to convert hydrogen and oxygen into electrical energy, and is equipped with an anode fuel inlet and outlet, a cathode oxidant inlet and outlet, and a tail exhaust port;

[0011] A solid-state hydrogen storage and supply module includes a fuel tank filled with aluminum trihydride material. The fuel tank is used to produce hydrogen through the thermal decomposition of aluminum trihydride and the hydrolysis of the thermal decomposition product, elemental aluminum, with the two reactions closely coupled. A fuel tank heater is provided on the outside of the fuel tank.

[0012] The heating-heating coupling module includes a heating-heating coupler and a common fan. The heating-heating coupler has a built-in heating rod, which is used to heat the fuel cell stack to the start-up temperature during the start-up phase and to cool the fuel cell stack and the fuel cell stack cathode exhaust gas during the stabilization phase. The common fan is used to regulate the heat in a coordinated manner.

[0013] The water recovery module includes a gas-liquid separator and a liquid pump. The gas-liquid separator is connected to the tail outlet of the fuel cell stack and is used to separate liquid water from the tail gas. The liquid pump is used to transport the separated water to the fuel tank so that it reacts with elemental aluminum to achieve hydrogen recycling.

[0014] The electronic control unit includes a temperature sensor, a pressure sensor, and an electronic control board. The temperature sensor is used to monitor the temperature of the fuel tank and the fuel cell stack. The pressure sensor is used to monitor the hydrogen pressure inside the fuel tank. The electronic control board is used to acquire the electrical signals from each sensor, control the operating parameters of each component, and collect the data required for efficiency calculation.

[0015] Furthermore, the fuel tank has a reaction space inside, and the aluminum trihydride material in the reaction space is filled by mixing tablets and powder, with aluminum trihydride powder filling the gaps between adjacent tablets.

[0016] Furthermore, during the startup phase, the control board powers on the heating rods to heat the fuel cell stack; during the stabilization phase, the control board de-powers the heating rods and uses a shared fan to dissipate heat from the fuel cell stack cathode exhaust gas flowing through the coupler channel. The speed of the shared fan is adjusted based on information obtained from the temperature sensor.

[0017] Furthermore, the water recovery module also includes a radiator and a water distributor. The first end of the radiator is connected to the cathode tail outlet of the fuel cell stack, and the second end is connected to the gas-liquid separator for cooling the cathode tail gas. The water distributor is a multi-point irrigation structure with several branch pipes arranged along the height of the fuel tank, evenly distributed in the gaps between the aluminum trihydride plates inside the fuel tank, for evenly spraying the separated water delivered by the liquid pump.

[0018] Furthermore, the fuel tank heater is a membrane heater, which is installed around the outside of the fuel tank. The membrane heater is equipped with a fuel tank temperature sensor to monitor the heating temperature in real time and feed it back to the electronic control board to control the heating temperature to be maintained at a preset temperature.

[0019] Furthermore, the solid-state hydrogen storage and supply module also includes a pressure relief valve, one end of which is connected to the fuel tank and the other end is connected to the outside. When the hydrogen pressure in the fuel tank exceeds the preset pressure, the pressure is automatically released.

[0020] Furthermore, the electronic control unit also includes a current sensor and a voltage sensor. The current sensor is used to monitor the output current of the fuel cell stack, and the voltage sensor is used to monitor the output voltage of the fuel cell stack. The electronic control board calculates the total power of the fuel cell stack and the net output power of the system based on the above electrical signals.

[0021] Secondly, this invention discloses a method for calculating hydrogen-to-electricity conversion efficiency based on the above system, comprising the following steps:

[0022] Step 1: Obtain the rated power of the fuel cell stack, the effective reaction area S per cell, the number of cells N per cell, the operating point of the cell, and the anode metering ratio k of the fuel cell stack; calculate the total output power of the fuel cell stack. The power consumption of the BOP system is calculated based on the sum of the power consumption of each auxiliary component. Typically, this is 15% to 20% of the fuel cell stack's power output, and the theoretical hydrogen consumption V per unit time of the fuel cell stack is... H2 The theoretical power output when the actual heat from hydrogen combustion consumed per unit time is completely used to do work. ;

[0023] The formula for calculating the power of the fuel cell stack is P. stk =S×I×U×N; I is the single-cell operating point current density, U is the single-cell operating point voltage;

[0024] V H2 =(S×I×60)÷(z×F)×22.4×N×k, where z is the number of H2 electrons, F is the Faraday constant, and I is the single-cell operating point current density;

[0025] V H2 ; The theoretical power output is the result of the heat released by the catalytic combustion of 1 L / min H2 doing work.

[0026] Step 2: Obtain the mass of aluminum trihydride in the fuel tank, and calculate the amount of elemental aluminum produced by the complete thermal decomposition of aluminum trihydride, the amount of hydrogen produced, and the theoretical hydrogen supply time T1 for the thermal decomposition of aluminum trihydride alone to supply hydrogen, according to reaction formula (2).

[0027] Step 3: Obtain the percentage of water recovered from the exhaust gas of the system, calculate the theoretical water production of the fuel cell stack and the amount of water recovered from the primary water production according to the reaction formula (1) and the anode metering ratio of the fuel cell stack, calculate the amount of hydrogen produced by the primary hydrolysis and the corresponding theoretical hydrogen supply time T2 according to the reaction formula (3), and calculate the amount of elemental aluminum consumed by hydrolysis and the amount of remaining aluminum. Calculate the amount of water recovered, hydrogen produced, and hydrogen supply time T3, T4, etc., for secondary, tertiary, etc. hydrolysis, as well as the amount of remaining aluminum, until the hydrogen produced by hydrolysis can no longer meet the hydrogen supply needs of the fuel cell stack.

[0028] Step 4: Accumulate T1, T2, T3... to obtain the theoretical total operating time T of the coupled hydrogen supply from pyrolysis and hydrolysis;

[0029] Step 5: Calculate the hydrogen-to-electricity conversion efficiency based on the theoretical operating time of the entire cycle, and quantify the hydrogen-to-electricity conversion efficiency using the following formula:

[0030] ;

[0031] The anode metering ratio k of the fuel cell stack is 1.02~1.1;

[0032] Hydrogen supply time = Hydrogen supply quantity / V H2 ;

[0033] Reaction formula (1):

[0034] Reaction (2): ;

[0035] Reaction (3): .

[0036] Compared with the prior art, the present invention has the following advantages:

[0037] 1. Utilizing AlH3 solid-state hydrogen storage effectively avoids the risks associated with high-pressure hydrogen storage. The single-chamber design of the fuel tank allows pyrolysis and hydrolysis to occur simultaneously within the material itself, resulting in high heat transfer efficiency. In the fuel cell system, the fuel tank has only one reaction chamber. During startup, hydrogen is first produced through pyrolysis within this single reaction chamber. After stable operation, the elemental aluminum (Al) produced by the thermal decomposition of aluminum trihydride continues to hydrolyze with water to produce hydrogen. The heat released during hydrolysis drives the thermal decomposition of the remaining aluminum trihydride. At this point, the thermal decomposition reaction and the hydrolysis of the Al product occur simultaneously within the material itself, resulting in high heat transfer efficiency and good heat transfer uniformity. This achieves a strong coupling of the material's own thermal decomposition and its own Al product hydrogen release reaction, resulting in high energy density. When applied to fuel cell systems, this is beneficial for improving the system's specific power.

[0038] 2. During the start-up phase, the fuel tank heater heats the aluminum trihydride (AlH3) in the fuel tank to decompose and produce hydrogen, which is then used as the anode fuel for the fuel cell stack. The fuel cell stack heater heats the stack to its start-up temperature. During the stable operation phase, the tail gas from the stack cathode is collected and sent to the radiator and high-efficiency gas-liquid separator. The liquid water recovered by the gas-liquid separator is transported to the fuel tank, where it reacts with the internal product, elemental aluminum, to produce hydrogen. At the same time, a large amount of heat is released to promote the thermal decomposition of aluminum trihydride (AlH3) to produce hydrogen. The two reactions are coupled together to supply the anode fuel for the fuel cell stack, realizing the recycling of hydrogen and thus improving the hydrogen-to-electricity conversion efficiency of the fuel cell system.

[0039] 3. The integrated design of the heating-heat dissipation coupler, which uses a single fan, reduces BOP power consumption. During the stable phase, the fuel tank heater is turned off, and the hydrothermal decomposition temperature is maintained by using hydrothermal decomposition heat, thus saving heating energy consumption.

[0040] 4. A fuel cell system with a rated power of ~65W, carrying 230.763g of aluminum trihydride, can theoretically operate continuously for 5 hours if relying solely on the thermal decomposition of AlH3 material to produce hydrogen. The system's hydrogen-to-electricity conversion efficiency is only 42.3%. If the parasitic power consumption of external heating required for the thermal decomposition of AlH3 material is calculated, the system's hydrogen-to-electricity conversion efficiency will be even lower. When using the system and operating method of this invention to recover water and achieve hydrogen recycling, the system can theoretically operate continuously for 8.3 hours, with a hydrogen-to-electricity conversion efficiency of over 70%, and achieves self-sustaining hydrogen supply reaction, reducing the parasitic power consumption of external electric heating. Due to the effective improvement in the system's hydrogen utilization rate, the operating time is extended from 5 hours for AlH3 pyrolysis alone to 8.3 hours.

[0041] 5. Traditional methods for calculating the hydrogen-to-electricity conversion efficiency of aluminum hydride-based fuel cell systems often focus on the instantaneous efficiency of hydrogen supply and power generation from single-stage thermal decomposition, which cannot adapt to the multi-stage hydrogen supply and energy cycle characteristics of solid-state hydrogen storage in this invention. Traditional methods only calculate the efficiency of hydrogen supply from aluminum hydride pyrolysis, ignoring the contribution of secondary hydrogen supply from hydrolysis. The hydrogen supply process of solid-state hydrogen storage in this invention is a coupled hydrogen supply mode of aluminum hydride pyrolysis and the hydrolysis of the product active aluminum. The proportion of hydrogen supply from these two reactions is not always fixed, and the instantaneous flow measurement of traditional methods cannot distinguish the proportion of hydrogen supply from the two reactions. The calculation method of this invention specifically solves this problem by accumulating the total operating time of pyrolysis and multiple hydrolysis processes, thereby achieving full life-cycle efficiency quantification. During the calculation process, operating time, total stack power, BOP power consumption, theoretical hydrogen power, etc., are obtained, and useful work is calculated by multiplying the total operating time by the net output power, incorporating the secondary hydrogen production benefit. This accurately reflects the efficiency improvement brought by water recovery and secondary hydrogen production, solving the problem of traditional methods underestimating the potential of solid-state hydrogen storage systems. Attached Figure Description

[0042] 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.

[0043] Figure 1 This is a front view of the internal structure of the fuel cell system of the present invention.

[0044] Figure 2 This is a schematic diagram of the rear structure of the internal structure of the fuel cell system of the present invention.

[0045] Figure 3 This is a schematic diagram of the external structure of the fuel tank module of the present invention.

[0046] Figure 4This is a schematic diagram of the internal fuel filling structure of the fuel tank module of the present invention.

[0047] Figure 5 This is a schematic diagram of the internal water distribution pipeline structure of the fuel tank module of the present invention.

[0048] Figure 6 This is a schematic diagram of a hydrogen production structure that combines a tail gas water recovery device with a fuel tank.

[0049] Figure 7 This is a front view of the internal structure of the fuel cell system of the present invention.

[0050] In the diagram: 1. Fuel stack module, 2. Fuel tank, 3. Fuel stack shroud, 4. Gas-liquid separator, 5. Heating-cooling coupler, 6. Liquid pump, 7. Gas pump, 8. Common fan, 9. Fuel tank heater, 10. Heating rod, 11. Tail exhaust valve, 12. Switch valve, 13. Pressure reducing valve, 14. Pressure relief valve, 15. Fuel stack temperature sensor, 16. Pressure sensor, 17. Control board, 18. Press, 19. Powder, 20. Water separator, 21. Gas outlet. 22. Connector; 23. Shut-off valve; A. Fuel tank temperature sensor; B. Fuel stack anode fuel inlet; C. Fuel stack cathode oxidant inlet; D. Fuel stack cathode oxidant outlet; E. Fuel tank hydrogen outlet; F. Fuel tank water inlet; G. Fuel stack anode periodic vent; H. Gas-liquid separator exhaust port; I. Pressure relief valve outlet; J. Liquid water dispersion outlet; K. Heating-heating coupler inlet; L. Heating-heating coupler outlet. Detailed Implementation

[0051] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0052] 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, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. 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.

[0053] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0054] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0055] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0056] For ease of description, spatial relative terms such as "above," "over," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation besides the orientation of the device as described in the figures. For example, if the device in the figures is inverted, a device described as "above" or "above" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0057] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0058] like Figures 1-7 As shown, an embodiment of the present invention discloses a fuel cell system, comprising:

[0059] The fuel cell module 1 is used to convert hydrogen and oxygen into electrical energy. It is equipped with an anode fuel inlet and outlet, a cathode oxidant inlet and outlet, and a tail discharge port. The fuel cell module 1 is also equipped with a periodic venting port for the anode of the fuel cell, which is used to periodically discharge the waste gas and wastewater accumulated in the anode circuit.

[0060] Solid-state hydrogen storage and supply module includes a fuel tank 2, which is filled with aluminum trihydride material. The fuel tank 2 is used to complete the thermal decomposition of aluminum trihydride to produce hydrogen and the hydrolysis of elemental aluminum, the thermal decomposition product, to produce hydrogen, as shown in reaction formulas (2) and (3). The two reactions are closely coupled. A fuel tank heater 9 is provided on the outside of the fuel tank.

[0061] The chemical reaction equation for hydrogen production is as follows:

[0062] (2)

[0063] (3)

[0064] The high-energy-density solid hydrogen storage material, aluminum trihydride (AlH3), used in this invention is one of the best solid-state hydrogen storage materials. It has a high hydrogen storage capacity at room temperature and pressure, with a hydrogen mass density of 10.08 wt% and a volumetric hydrogen storage density of 148 g / L. AlH3 has a low hydrogen release temperature, meaning that after physical or chemical modification, it can rapidly release hydrogen at relatively low temperatures of 60-200℃, offering significant advantages in safety and efficiency. It avoids the high-pressure leakage risk associated with high-pressure gaseous hydrogen storage and also outperforms traditional high-pressure gaseous hydrogen storage and other solid-state hydrogen storage materials in terms of hydrogen storage density, which is beneficial for improving the volumetric and mass power-to-weight ratio of fuel cell systems.

[0065] As an optional implementation, the battery stack shroud 3 is also included. It is installed outside the battery stack module, with the air inlet connected to the common fan outlet and the air outlet connected to the air inlet of the heating-cooling coupler, forming a closed airflow channel. This forces the fan airflow to flow through the battery stack surface and the heating-cooling coupler, enhancing heat exchange efficiency, reducing heat loss, and protecting the battery stack from external impurities.

[0066] The function of the aforementioned tailpipe is mainly achieved through the tailpipe valve 11.

[0067] The solid hydrogen storage device's fuel tank is filled with aluminum trihydride (AlH3) material, which can release high-purity hydrogen through thermal decomposition at a certain temperature. The elemental aluminum produced by thermal decomposition can rapidly undergo hydrolysis with water to produce hydrogen. At the same time, the heat released by the hydrolysis reaction promotes the thermal decomposition of the remaining aluminum trihydride (AlH3) inside. The two reactions are coupled to release hydrogen, and the reaction is self-sustaining, saving the power consumption of heating for thermal decomposition and hydrogen release.

[0068] The heating-heating coupling module includes a heating-heating coupler 5 and a common fan 8. The heating-heating coupler 5 has a built-in heating rod 10, which is used to heat the stack to the start-up temperature during the start-up phase and to cool the stack cathode and stack exhaust gas during the stabilization phase. The common fan 8 is used to regulate the heat in a coordinated manner.

[0069] Specifically, the stack heater during the startup phase of the fuel cell system is integrated with the stack cathode exhaust gas radiator during stable operation. It heats the stack during startup and is used for stack cooling and stack cathode exhaust gas cooling to recover moisture during system operation. It shares a cooling fan with the system.

[0070] The water recovery module includes a gas-liquid separator 4 and a liquid pump 6. The gas-liquid separator 4 is connected to the tail outlet of the fuel cell stack and is used to separate liquid water from the tail gas, which is then discharged through the liquid water dispersion outlet J. The liquid pump 6 is used to transport the separated water to the fuel tank 2, where it reacts with elemental aluminum to achieve hydrogen recycling. The gas-liquid separator 4 is equipped with a gas-liquid separator exhaust port H. The dry tail gas after gas-liquid separation is discharged through the gas-liquid separator exhaust port H, maintaining stable pressure inside the gas-liquid separator.

[0071] The electronic control unit includes a temperature sensor, a pressure sensor 16, and an electronic control board 17. The fuel cell stack temperature sensor 15 is used to monitor the fuel cell stack temperature. A fuel tank temperature sensor 23 is installed inside the fuel tank to monitor the fuel tank temperature. The pressure sensor 16 is used to monitor the hydrogen pressure inside the fuel tank 2. The electronic control board 17 is used to acquire the electrical signals of each sensor, control the operating parameters of each component, and collect the data required for efficiency calculation.

[0072] Specifically, the fuel tank 2 has a reaction space inside, and the aluminum trihydrogenation material in the reaction space is filled by a mixture of compressed tablets 18 and powder 19. The compressed tablets can increase the amount of material filled and are also beneficial for heat transfer. The gaps between adjacent compressed tablets are filled with aluminum trihydrogenation powder.

[0073] Specifically, in actual use, during the start-up phase, the fuel cell system uses a lithium battery to drive the fuel tank heater 9 to heat the AlH3 in the fuel tank 2 to decompose and produce hydrogen, which is used as anode fuel. It enters the fuel cell module 1 from the anode fuel inlet A and is discharged from the anode fuel outlet B. The discharged components are mainly unreacted hydrogen, permeated nitrogen and trace amounts of water vapor. The cathode is fed by the air pump 7, enters from the cathode oxidant inlet C and is discharged from the cathode oxidant outlet D. The discharged components are mainly unreacted air components, water vapor generated by the reaction and trace amounts of impurities. Hydrogen and oxygen undergo an electrochemical reaction in the fuel cell stack (1) to achieve external power supply.

[0074] (1)

[0075] During the startup phase, the control board uses lithium batteries to power the heating rods, heating the stack temperature to provide heat for the decomposition of AlH3 in the fuel tank to produce hydrogen. During the stabilization phase, the control board controls the heating rods to de-energize, and uses a shared fan to dissipate heat from the stack cathode exhaust gas flowing through the coupler channel, while also cooling the stack itself. The speed of the shared fan is adjusted based on information obtained from the temperature sensor.

[0076] During the stable operation phase of the system, the tail gas of the stack cathode is collected and fed into the high-efficiency gas-liquid separator 4. The liquid water recovered by the gas-liquid separator 4 is transported to the fuel tank 2 and undergoes hydrolysis reaction with the internal product elemental aluminum to continue producing hydrogen. At the same time, a large amount of heat is released to promote the thermal decomposition of the remaining AlH3 to release hydrogen. The two reactions (2) and (3) are coupled together to supply the stack anode, realize the recycling of hydrogen, and thus improve the overall system efficiency of the fuel cell module. Conventionally, the stack anode is also equipped with a periodic venting port G.

[0077] The water recovery module also includes a radiator and a water distributor 20. The first end of the radiator is connected to the tail outlet of the cathode of the fuel cell stack, and the second end is connected to the gas-liquid separator for cooling the cathode tail gas. The water distributor is a multi-point irrigation structure for providing external liquid water. It has several branch pipes arranged along the height of the fuel tank and evenly distributed in the gaps between the aluminum trihydride plates in the fuel tank. It is used to evenly spray the separated water delivered by the liquid pump. After the water is more evenly distributed, it is beneficial to the uniformity of reaction and heat transfer.

[0078] After multiple cycles of AlH3 thermal decomposition reaction are complete, only aluminum hydrolysis reaction remains. At this point, you can choose to shut down the machine or replace fuel tank 2. If there is an external water source, you only need to consider controlling hydrogen production by feeding water into the aluminum hydrolysis reaction until the reactants are exhausted or the amount of reactants is too small to cause an effective reaction. After that, shut down the machine or replace fuel tank 2.

[0079] The fuel tank heater 9 is a membrane heater, surrounding the outside of the fuel tank. A fuel tank temperature sensor 23 is installed on the membrane heater to monitor the heating temperature in real time and feed it back to the electronic control board 17, controlling the heating temperature to be maintained at a preset temperature. The fuel tank heater 9 is used to regulate the tank temperature to control the rate of hydrogen production from the thermal decomposition of AlH3 in the absence of an external water source. In the fuel cell system, the fuel tank heater 9 can first be used to heat the fuel tank 2 for thermal decomposition to produce hydrogen. After the fuel cell system is running, a water recovery device can be used to recover the liquid water recovered from the stack exhaust gas to achieve the above-mentioned coupled thermal decomposition and water electrolysis hydrogen production operation. In this embodiment, the membrane heater uses a polyimide heating membrane.

[0080] The solid-state hydrogen storage and supply module also includes a pressure relief valve 14. One end of the pressure relief valve 14 is connected to the fuel tank 2, and the other end is connected to the outside. When the hydrogen pressure in the fuel tank 2 exceeds the preset pressure, it automatically releases pressure. After overpressure, the internal gas will be quickly discharged from the outlet I of the pressure relief valve, reducing the internal pressure to a suitable range. The pressure relief valve 14 is equipped with a quick-connect fitting 21 for gas discharge. A shut-off valve 22 is installed on the pipeline where the quick-connect fitting 21 is located. When the fuel tank 2 cooperates with the fuel cell stack module 1 to supply hydrogen, the internal hydrogen gas is supplied to the outside from the outlet of the quick-connect fitting 21, i.e., the hydrogen outlet E of the fuel tank. A switching valve 12 is set between the hydrogen outlet E of the fuel tank and the pressure reducing valve 13, which serves as the main switch for hydrogen supply. It is opened when the system starts up upon receiving a signal from the control board, and quickly cuts off the hydrogen supply circuit when the system stops or malfunctions. It forms a safety control logic of first opening and then reducing pressure with the pressure reducing valve. The valve is located at the top of the fuel tank storage space and is connected to the input end of the switching valve 12 via a flange. The output of the pressure reducing valve is connected to the anode fuel inlet A of the fuel cell stack via a pipeline, which reduces the pressure of the hydrogen gas output from the fuel tank to the fuel cell stack's appropriate pressure.

[0081] During system operation, the cathode exhaust gas from fuel cell module 1 enters the integrated heating-heating coupler 5 through the heating-heating coupler inlet K and is cooled. Then, it enters the gas-liquid separator 4 through the heating-heating coupler outlet L for gas-liquid separation. Liquid water is pumped by the liquid pump 6 to the fuel tank 2, where it undergoes hydrolysis with elemental aluminum (AlH3 thermal decomposition product) to produce hydrogen. Simultaneously, the released heat drives the thermal decomposition of the remaining aluminum trihydride. These two reactions work together to supply the anode of fuel cell module 1, achieving hydrogen recycling and improving the overall system efficiency of the fuel cell system. If other water sources are available or spare liquid water is carried, the system's operating time can be further extended. Specifically, the fuel tank inlet F serves as the inlet of the fuel tank water inlet pipe, protruding a certain height from the fuel tank. The heating-heating coupler 5 features a highly integrated heating and cooling design. During startup, it uses the embedded heating rod 10 to heat the fuel cell module 1. During system operation, it is used for cooling the cathode exhaust gas and shares a cooling fan with the system, namely the shared fan 8.

[0082] The electronic control unit also includes a current sensor and a voltage sensor. The current sensor is used to monitor the output current of the fuel cell stack, and the voltage sensor is used to monitor the output voltage of the fuel cell stack. The electronic control board calculates the total power of the fuel cell stack and the net output power of the system based on the above electrical signals.

[0083] For the aluminum trihydride-based fuel cell system in this embodiment, its innovative design of pyrolysis-water electrolysis coupled hydrogen supply and water recycling cycle cannot be accurately evaluated by traditional fuel cell efficiency calculation methods. Therefore, this invention discloses a hydrogen-to-electricity conversion efficiency calculation method based on the above system to accurately calculate and verify the improvement effect of hydrogen-to-electricity conversion efficiency, ensuring that the innovative design of the system can be effectively transformed into performance advantages.

[0084] The method specifically includes the following steps:

[0085] Step 1: Obtain the rated power of the fuel cell stack, the effective reaction area S per cell, the number of cells N per cell, the operating point per cell, and the anode metering ratio k of the fuel cell stack (values ​​range from 1.02 to 1.1); calculate the total output power of the fuel cell stack. The power consumption of the BOP system is calculated based on the sum of the power consumption of each auxiliary component. Typically, this is 15% to 20% of the fuel cell stack's power output, and the theoretical hydrogen consumption V per unit time of the fuel cell stack is... H2 The theoretical power output when the actual heat from hydrogen combustion consumed per unit time is completely used to do work. ;

[0086] The formula for calculating the power of the fuel cell stack is Pstk=S×I×U×N; where S is the effective reaction area of ​​a single cell, I is the current density at the operating point of a single cell, and U is the voltage at the operating point of a single cell.

[0087] VH2 =(S×I×60)÷(z×F)×22.4×N×k, where z is the number of H2 electrons, F is the Faraday constant, 60 is the unit conversion factor (seconds), 22.4 is the molar volume of the gas, and I is the single-cell operating point current density;

[0088] V H2 ; The theoretical power output is the result of the heat released by the catalytic combustion of 1 L / min H2 doing work.

[0089] Step 2: Obtain the mass of aluminum trihydride in the fuel tank, and calculate the amount of elemental aluminum produced by the complete thermal decomposition of aluminum trihydride, the amount of hydrogen produced, and the theoretical hydrogen supply time T1 for the thermal decomposition of aluminum trihydride alone to supply hydrogen, according to reaction formula (2).

[0090] Step 3: Obtain the percentage of water recovered from the exhaust gas of the system. According to the reaction formula (1) and the anode metering ratio of the fuel cell stack, calculate the theoretical water production of the stack and the amount of water recovered from the primary water production. According to the reaction formula (3), calculate the amount of hydrogen produced by the primary hydrolysis and the corresponding theoretical hydrogen supply time T2, and calculate the amount of elemental aluminum consumed by the hydrolysis and the amount of remaining aluminum. Calculate the amount of water recovered, the amount of hydrogen produced, and the hydrogen supply time T3, T4, etc., and the amount of remaining aluminum for the secondary, tertiary, etc., hydrolysis in sequence until the amount of hydrogen produced by the hydrolysis cannot meet the hydrogen supply requirements of the stack.

[0091] Step 4: Accumulate T1, T2, T3... to obtain the theoretical total operating time T of the coupled hydrogen supply from pyrolysis and hydrolysis;

[0092] Step 5: Calculate the hydrogen-to-electricity conversion efficiency based on the theoretical operating time of the entire cycle, and quantify the hydrogen-to-electricity conversion efficiency using the following formula:

[0093] .

[0094] The hydrogen supply time is the hydrogen production rate divided by the hydrogen consumption per unit time at the operating point; a single cell refers to the basic unit that completes the electrochemical reaction inside the fuel cell stack.

[0095] The theoretical hydrogen consumption V per unit time of the reactor is derived. H2 The steps include: obtaining the stoichiometric ratio k of the fuel cell anode, combined with the Faraday constant F, the number of electrons z, and the gas molar volume of 22.4 L / mol; calculating the theoretical amount of hydrogen required based on the hydrogen content derivation formula, wherein the hydrogen content derivation formula is V H2 =(S×I×60)÷(z×F)×22.4×N×k, where S is the effective reaction area of ​​a single cell, I is the working current density of a single cell, and 60 is the unit conversion factor (seconds).

[0096] Get The steps are as follows: Obtain the calorific value of hydrogen per unit mass (~120 MJ / kg) from the material list, and calculate the theoretical power output when the heat released by 1 L / min H2 catalytic combustion is fully utilized for work. for ; V H2 .

[0097] This invention proposes a method for calculating the hydrogen-to-electricity conversion efficiency of a fuel cell system. It can be expressed as the proportion of the energy (theoretical calorific value Q) that the system can theoretically generate with fuel over a period of time is converted into useful work (W). In this embodiment, W is the effective energy output by the fuel cell system during the process, which is the net output energy after deducting the system's auxiliary power consumption, rather than the total output energy of the stack. This is consistent with the actual engineering scenario of considering the power consumption of the BOP system in this invention. The calculation method is η=(W / Q)×100%;

[0098] Unlike traditional fuel cells, in this invention, the water from the recovered exhaust gas is hydrolyzed with elemental Al (a product of aluminum trihydride AlH3) to produce hydrogen, which is then recycled back into the fuel cell stack after water production. This continuous, real-time cycle theoretically continues multiple times until the reactants are exhausted. It's important to clarify that the instantaneous efficiency during system operation is not improved; rather, the efficient hydrogen recycling increases fuel utilization and extends the system's continuous operating time (T), thereby improving the hydrogen-to-electricity conversion efficiency of the fuel cell system. The specific calculation method of this invention is as follows:

[0099] Let T1 be the time that the initial amount of aluminum trihydride (AlH3) carried by the system can supply for the reactor to operate after complete thermal decomposition and hydrogen release (i.e., the initial amount of hydrogen carried by the fuel tank). The process of releasing hydrogen through complete thermal decomposition and feeding it into the reactor's product water is defined as primary product water. The process of releasing hydrogen through primary product water and then reacting it with the hydrogen produced by the hydrolysis of elemental Al (a thermal decomposition product) into the reactor's product water is defined as secondary product water. The process of releasing hydrogen through secondary product water and then reacting it with the hydrogen produced by the hydrolysis of elemental Al (a thermal decomposition product) into the reactor's product water is defined as tertiary product water. The process of releasing hydrogen through secondary product water and then reacting it with the hydrogen produced by the hydrolysis of elemental Al (a thermal decomposition product) into the reactor's product water is defined as tertiary product water. Hydrogen produced by the hydrolysis of elemental Al enters the fuel cell stack to produce water in four stages... Let T2 be the anode gas supply time for the first stage of water recovery in the aluminum hydrolysis reactor, T3 for the second stage, T4 for the third stage, T5 for the fourth stage, and so on. The gas supply time is the hydrogen production rate in that stage divided by the hydrogen consumption per unit time at the stack's operating point. This cycle continues, and the system's hydrogen-to-electricity conversion efficiency is expressed by the following formula:

[0100]

[0101] Useful work System net output power Total power output of the fuel cell stack The power consumption of the BOP system is Then there is , For the continuous operating time of the system, the formula above is T1 + T2 + T3 + T4 + T5 + ... = T; where Q is the theoretical heat released by the complete combustion of the hydrogen initially carried in the fuel tank, which can be obtained from the material table as ~120 MJ / kg of hydrogen per unit mass. To facilitate comparison of the numerator and denominator in the above formula, Q can also be written in the following form: ,in This refers to the heat released by the complete combustion of hydrogen actually consumed per unit time during system operation, which is also the theoretical power output that can be achieved by fully utilizing the heat released from the combustion of hydrogen actually consumed per unit time. The theoretical power output when the heat released from the combustion of 1 L / min H2 is fully utilized is... (Hydrogen density 0.0899 g / L), if the fuel cell stack consumes 0.856 L / min of hydrogen at a certain operating point, then T1 represents the time it takes for the hydrogen initially carried by the fuel tank to power the reactor.

[0102] This invention's integrated calculation method covers the entire lifecycle, eliminating the need for complex sensors to distinguish the instantaneous hydrogen supply ratio between pyrolysis and hydrolysis. This completely solves the problem of inaccurate flow monitoring when both reactions supply hydrogen simultaneously, reducing system hardware costs and technical complexity. By accumulating the theoretical total operating time T, it encompasses the full lifecycle benefits of pyrolysis, multiple hydrolysis cycles, and hydrogen recycling, avoiding efficiency assessment biases caused by instantaneous fluctuations in real-time calculations. The results more accurately reflect the system's true performance. Furthermore, it fully reflects the extended operating range benefits brought by exhaust gas water recovery and hydrolysis hydrogen supply. Compared to traditional methods that only calculate pyrolysis hydrogen supply, this invention better highlights the core value of its hydrogen cycle design.

[0103] In this embodiment, the hydrogen-to-electric conversion efficiency calculation method for a fuel cell system with a rated power of approximately 65W is calculated using the method proposed in this invention, with an effective reaction area of ​​30cm² per cell in the fuel cell stack. 2 It consists of 13 individual cells. Under the condition of an anode metering ratio of 1.05 (typically 1.02~1.1) in the fuel cell stack, the operating point of a single cell is 300 mA / cm. 2 At 0.685V, the hydrogen consumption flow rate (hydrogen consumption per unit time at the operating point) is calculated as follows: (V = It / zF * 22.4 * 13 sections * 1.05 = (30cm³)) 2 * 300mA / cm 2* 60s) / (2*96485)*22.4*13*1.05≈0.856L / min (~0.077g / min), where t is time in seconds; 22.4 is the molar volume of gas in L / mol; z is the number of electrons in H2; and F is the Faraday constant 96485Cmol. -1 The power output of the fuel cell stack (total power output of the fuel cell stack) is Pstk = 30cm. 2 *300mA / cm 2 *0.685V * 13 sections = 80.145W, the power consumption of the BOP system is =15W (usually accounting for 15~20% of the fuel cell power), when the exhaust gas water recovery rate is 85% (the recovery rate of a conventional water recovery unit is 80~95%), the water recovery rate is 5.82g / min;

[0104] The system carries 230.763g of aluminum trihydride. Theoretically, the hydrogen supply time for its complete thermal decomposition reaction (supply time is the hydrogen production rate in this stage divided by the hydrogen consumption per unit time at the operating point, 0.856L / min) is 5 hours (T1). The amount of aluminum produced during decomposition is... Hydrogen production Water production

[0105] This invention proposes a method for calculating the hydrogen-to-electricity conversion efficiency of a fuel cell system, which will... When hydrogen is produced by complete thermal decomposition and fed into the fuel cell stack, the resulting water is designated as primary water production. With an 85% tail gas water recovery rate, the primary water recovery rate is... During the Al hydrolysis reaction, the amount of Al produced is consumed. Remaining Al amount Hydrogen production from hydrolysis reaction g; This amount of hydrogen can supply hydrogen time ;

[0106] The water produced from the initial Al hydrolysis hydrogen production and fed into the fuel cell stack is designated as secondary water production. The water production volume is... Secondary product water recovery volume When the aluminum hydrolysis reaction is fully carried out, the amount of Al produced is consumed. Remaining Al amount Hydrogen production from hydrolysis reaction g; This amount of hydrogen can supply hydrogen time ;

[0107] The secondary Al hydrolysis hydrogen production is incorporated into the fuel cell stack reaction water as a tertiary water production process, with a water production volume of... The amount of water recovered in the three stages When the aluminum hydrolysis reaction is fully carried out, the amount of Al produced is consumed. Remaining Al amount Hydrogen production from hydrolysis reaction g; This amount of hydrogen can supply hydrogen time ;

[0108] The hydrogen production from three Al hydrolysis processes is converted into a four-stage water production process using the fuel cell stack. The water production volume is... The amount of water recovered in the four production cycles When the aluminum hydrolysis reaction is fully carried out, the amount of Al produced is consumed. Remaining Al amount Hydrogen production from hydrolysis reaction g; This amount of hydrogen can supply hydrogen time Theoretically, the cycle can continue until the reaction can no longer meet the system's hydrogen supply needs, which is related to the effective control of hydrogen supply through good coupling of the system's reaction.

[0109] At this point, based on the sum of T1 to T5 above, the theoretical total time T = 8.309h can be obtained.

[0110] At the aforementioned operating point, the fuel cell stack consumes 0.856 L / min of hydrogen, and the theoretical power output is calculated based on the heat released from the catalytic combustion of 1 L / min of H2, which is then fully utilized for work. For a fuel cell system with a power rating of 180W, if the system lacks the water recovery and efficient hydrogen recycling functions described in this invention and relies solely on the thermal decomposition of aluminum trihydride for hydrogen supply, the hydrogen-to-electricity conversion efficiency of the system is calculated as follows:

[0111]

[0112]

[0113] If the fuel cell system utilizes the water recovery and efficient hydrogen cycling functions of this invention, and uses the thermal decomposition of aluminum trihydride and its products for hydrogen supply, the system's hydrogen-to-electricity conversion efficiency is calculated as follows:

[0114]

[0115] If the system relies solely on the thermal decomposition of AlH3 material to produce hydrogen, it can operate continuously for 5 hours, with a hydrogen-to-electricity conversion efficiency of 42.3%. However, if the parasitic power consumption from external heating required for the thermal decomposition of AlH3 material is calculated, the system efficiency will be even lower. When the system and operating method of this invention are used to recycle water and achieve hydrogen recycling, the system can operate continuously for 8.3 hours, with a hydrogen-to-electricity conversion efficiency of over 70%. Furthermore, the hydrogen supply reaction is self-sustaining, reducing the parasitic power consumption from external electric heating.

[0116] As can be seen from the above calculations, due to factors such as reaction characteristics and water recovery rate, the amount of recovered water is not infinitely sufficient and cannot completely react with all the elemental aluminum products generated by the thermal decomposition of aluminum hydride. Therefore, the theoretical aluminum content of aluminum hydride cannot be used to calculate the fuel utilization rate and system efficiency. Thus, the above method for calculating the efficiency of fuel cell systems is more practical and has a reasonable and scientific basis.

[0117] The system operation method mentioned in this invention achieves efficient hydrogen cycling, meaning that fuel utilization continuously improves during the cycle, thus extending the system operating time T and thereby increasing the hydrogen-to-electricity conversion efficiency of the fuel cell system. In this invention, the water source is generated by the internal reaction of the fuel cell stack, and hydrogen recycling is achieved through tail gas recovery. Therefore, the tail gas water recovery efficiency is also a key factor affecting the utilization rate of fuel.

[0118] This invention proposes a fuel cell system and a method for calculating system efficiency improvement. By utilizing aluminum trihydride (AlH3), a high-energy-density solid hydrogen storage material capable of storing hydrogen at atmospheric pressure while releasing hydrogen at relatively low temperatures, the system optimizes the thermal decomposition of metal hydrides and their coupling reaction with water in the solid hydrogen storage tank. Hydrogen is produced by the hydrolysis of elemental aluminum (Al), a byproduct of the aluminum trihydride thermal decomposition reaction, with water. Simultaneously, the heat released from the hydrolysis reaction promotes the thermal decomposition of the remaining aluminum trihydride (AlH3). The coupling of these two reactions releases hydrogen, achieving efficient heat utilization. Within the fuel cell system, hydrogen can be produced by recovering water from the fuel cell exhaust gas. A device that comprehensively utilizes the thermal decomposition of AlH3 and the hydrolysis of aluminum provides hydrogen to the fuel cell. By combining the heat absorption and release processes of various system components, thermal coupling and matching relationships are designed to construct a system for hydrogen and water circulation, achieving efficient utilization of hydrogen circulation and internal heat, thereby improving system efficiency.

[0119] The core requirements for energy equipment in industrial settings are low energy consumption and high output. Traditional solid-state hydrogen fuel cells, neglecting secondary hydrogen supply through water electrolysis, have long suffered from efficiencies below 50%, failing to meet industrial-grade energy consumption standards. This system, through an innovative design of pyrolysis-water electrolysis coupling and water recycling, verifies that its hydrogen-to-electricity conversion efficiency can reach over 70%, surpassing traditional commercial high-pressure gaseous hydrogen fuel cells (40-60%), while also avoiding the safety risks of high-pressure hydrogen storage. This efficiency result meets the core access standards for performance verification in the laboratory stage and industrial pilot production. However, to stably reproduce this high efficiency in laboratory testing or actual production scenarios, it is necessary to rely on the coordinated control of system hardware, such as the electronic control unit, sensors, and heat dissipation coupling modules, and to clearly define the complete operating logic from startup to stable operation, ensuring that each component operates in conjunction with preset parameters. Based on this, this embodiment further discloses the specific operating method of the above system. Specifically,

[0120] In the startup phase, the electronic control board receives signals from the stack temperature sensors, activates the fuel tank electric heater and the heating rod in the heating-cooling coupler, and the AlH3 in the fuel tank starts to thermally decompose. The pressure sensor monitors the hydrogen pressure. When the hydrogen pressure rises to the preset standard, the electronic control board opens the outlet switch valve of the fuel tank; the hydrogen gas enters the anode of the stack through a pressure reducing valve;

[0121] The air pump starts and delivers air to the cathode of the stack. The stack starts to generate electricity. The current sensor monitors the output current, and the voltage sensor monitors the output voltage to calculate the total output power of the stack , and the power consumption of the BOP system is . When the stack temperature and the running time reach the preset targets, it is confirmed that the stack enters the stable phase.

[0122] During the stable phase, the electronic control board turns off the heating rod and the fuel tank electric heater, starts the liquid pump, and sprays the recovered liquid water in the gas-liquid separator into the fuel tank through the branch pipe of the water separator; the water undergoes hydrolysis with the Al, the pyrolysis product of AlH3, to release heat to maintain the pyrolysis temperature of the remaining AlH3. The pressure sensor monitors the hydrogen pressure. If the hydrogen pressure is too high, the liquid pump is turned off; if the hydrogen pressure is too low, the liquid pump is restarted; when the hydrogen pressure continuously remains less than the preset value, the system stops running.

[0123] If the actual total running time deviates from the theoretical total time T by a preset deviation, the electronic control system can locate the abnormal link and prompt the solution by tracing the collectible parameters in each phase. Specifically, in the startup phase, the electronic control system monitors the fuel tank temperature, the hydrogen pressure rise time, and the initial power of the stack to calibrate the influence of the pyrolysis phase on the total time T. In the stable phase, by monitoring the hydrogen pressure stability, the stack power fluctuation, the BOP power consumption, etc., it indirectly judges whether the hydrogen supply by hydrolysis is normal, and then calibrates the influence of its water inlet frequency and single water inlet volume on the total time T. When the actually collected total running time is within the preset range of the theoretical value, it is determined that the system operation conforms to the theoretical expectation, and the electronic control board automatically stores the calibration parameters in each phase as the benchmark for subsequent batch operations.

[0124] Compared with the prior art which requires manual monitoring of hydrogen production pressure and temperature, there are operation risks. The electronic control unit of this technology integrates sensors such as temperature and pressure. The electronic control board can automatically execute the linkage logics of heating, hydrogen supply, heat dissipation, water recovery, etc., to achieve unattended operation.

[0125] Traditional methods for calculating the hydrogen-to-electricity conversion efficiency of aluminum hydride-based fuel cell systems often focus on the instantaneous efficiency of hydrogen supply and power generation from a single thermal decomposition process. These methods are ill-suited to the multi-stage hydrogen supply and energy cycle characteristics of solid-state hydrogen storage in this invention. Traditional methods only calculate the efficiency of hydrogen supply from aluminum hydride pyrolysis, neglecting the contribution of secondary hydrogen supply from hydrolysis. Furthermore, the hydrogen supply process of solid-state hydrogen storage in this invention is a coupled hydrogen supply mode of aluminum hydride pyrolysis and the hydrolysis of the product active aluminum. The proportion of hydrogen supply from these two reactions is not always fixed, and the instantaneous flow rate measurement of traditional methods cannot distinguish the proportion of hydrogen supply from the two reactions. The calculation method of this invention specifically addresses this problem by calculating T based on the cumulative total operating time of pyrolysis and multiple hydrolysis processes, thereby achieving full life-cycle efficiency quantification. The calculation process incorporates the theoretical time T and the total power of the fuel cell stack. BOP power consumption Theoretical hydrogen power P h The useful work is calculated by multiplying the total operating time by the net output power and included in the secondary hydrogen production revenue. This accurately reflects the efficiency improvement brought about by water recycling and secondary hydrogen production, solving the problem of traditional methods underestimating the potential of solid-state hydrogen storage systems. In addition, traditional methods often ignore the power consumption of the BOP system (such as fans and liquid pumps), resulting in an overestimation of efficiency values. In the calculation process of this invention, the power consumption of the BOP is explicitly deducted, and the useful work is calculated based on the net output power, so the results are closer to the actual application scenarios of solid-state hydrogen storage.

[0126] Furthermore, the intelligent data calculation process of the present invention includes:

[0127] The stack output current I is monitored by a current sensor, and the stack output voltage U is monitored by a voltage sensor. The control board calculates the total power of the stack based on these data, without the need for real-time efficiency calculation. The control board also calculates the rated power consumption of components such as air pump 7, liquid pump 6, common fan 8, and fuel tank heater 9, which serves as the basis for calculating the power consumption of the BOP system.

[0128] When the system uses only aluminum trihydride for hydrogen supply under certain conditions, during the startup phase, the timer automatically starts and records the hydrogen supply time T1 for aluminum trihydride alone. When the hydrogen pressure continues to be lower than the standard value and cannot recover, the system stops running. The electronic control board automatically records the total running time T (at this time, T is equal to T1), and substitutes it into the hydrogen-to-electricity conversion efficiency formula of the present invention to calculate the final efficiency. The pressure sensor monitors the hydrogen pressure in real time and is used to provide feedback on the start and stop of the heating membrane.

[0129] When the system can utilize the thermal decomposition of aluminum trihydride and its product hydrolysis to supply hydrogen under certain conditions, during the startup phase, the timer automatically starts and records the hydrogen supply time. When the hydrogen pressure remains below the standard value and cannot recover, the system stops operating. The electronic control board automatically records the total operating time T (at this time, T = T1 + T2 + T3 + T4 + T5 + ...), and substitutes it into the hydrogen-to-electricity conversion efficiency formula of the present invention to calculate the final efficiency. The pressure sensor monitors the hydrogen pressure in real time and is used to provide feedback to regulate the start and stop of the liquid pump.

[0130] If the system performance suddenly drops during operation, the control board will automatically check the sensor data: if the pressure sensor shows a sudden drop in hydrogen pressure, it will determine that the hydrogen supply from the fuel tank is abnormal, check for leaks or replace the fuel tank if the fuel is exhausted; if the temperature sensor shows an over-temperature alarm for the fuel cell stack, it will automatically increase the fan speed and cut off some unnecessary loads.

[0131] The control board automatically stores the P value for each run. stk P BOP Data such as T and η are used to generate efficiency trend curves and provide real-time prompts to users to replace fuel tanks or maintain the water recovery module. Based on historical data, the electronic control board automatically optimizes the threshold values ​​of key parameters in the formula to further improve overall lifecycle efficiency.

[0132] Through the aforementioned intelligent control, the system can achieve efficient operation and real-time monitoring without human intervention, further solving the problems of lagging efficiency calculation and reliance on manual adjustment in traditional fuel cells.

[0133] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method of calculating hydrogen electro-conversion efficiency of a fuel cell system, characterized by, The fuel cell system comprises: A stack module for converting hydrogen and oxygen into electric energy, provided with an anode fuel inlet and outlet, a cathode oxidant inlet and outlet, and a tail gas outlet; A solid-state hydrogen storage hydrogen supply module, comprising a fuel tank filled with aluminum trihydride material, the fuel tank being used for completing hydrogen production by thermal decomposition of aluminum trihydride and hydrogen production by hydrolysis of thermal decomposition product elemental aluminum, the two reactions being closely coupled, and the fuel tank being provided with a fuel tank electric heater outside; A heating-heat dissipation coupling module, comprising a heating-heat dissipation coupling device with a heating rod built-in, for heating the stack to a starting temperature in a starting stage and cooling the stack and cathode tail gas in a stable stage, and a common fan for linkage adjustment of heat; A water recovery module, comprising a gas-liquid separator connected to the stack tail gas outlet for separating liquid water in the tail gas, and a liquid pump for conveying the separated water to the fuel tank to react with elemental aluminum to realize hydrogen circulation; An electronic control unit, comprising a temperature sensor for monitoring the temperature of the fuel tank and the stack, a pressure sensor for monitoring the hydrogen pressure in the fuel tank, and an electronic control board for acquiring electric signals of the sensors, controlling operating parameters of the components, and collecting data required for efficiency calculation; A hydrogen-electric conversion efficiency calculation method of the fuel cell system, comprising the following steps: Step 1: Obtain the rated power of the stack, the effective reaction area S of the single cell of the stack, the number of single cell N, the single cell working point and the fuel cell stack anode metering ratio k; calculate the total power output of the stack to the outside , based on the sum of the power consumption of each auxiliary component to calculate the power consumption of the BOP system , the theoretical hydrogen consumption of the stack per unit time V H2 and the theoretical power output of the hydrogen combustion heat completely done per unit time ; The formula for calculating the total output power of the stack is: P stk =S x I x U x N; I is the single-cell working point current density, and U is the single-cell working point voltage. V H2 = (S x I x 60) ÷ (z x F) x 22.4 x N x k, z is the number of electrons of H2, F is the Faraday constant, I is the single-cell working point current density; V H2 ; Theoretical power output for 1 L / min H2catalytic combustion released heat to do work completely; Step 2: obtaining the mass of aluminum trihydride in the fuel tank, and calculating the amount of elemental aluminum produced by complete thermal decomposition of aluminum trihydride, the amount of hydrogen produced, and the theoretical hydrogen supply time T1 of thermal decomposition of aluminum trihydride alone according to reaction formula (2); Step 3: Obtain the percentage of tail gas water recovery of the system, calculate the theoretical water production of the stack and the recovered water of the first water production according to the reaction formula (1) and the anode metering ratio of the fuel cell stack, calculate the hydrogen production of the first hydrolysis and the corresponding theoretical hydrogen supply time T2 according to the reaction formula (3), and calculate the amount of elemental aluminum consumed by hydrolysis and the remaining aluminum amount; Calculate the recovered water, hydrogen production, hydrogen supply time T3, T4…… and remaining aluminum amount of secondary, tertiary…… hydrolysis until the hydrogen production of hydrolysis cannot meet the hydrogen supply demand of the stack. Step 4: accumulating T1, T2, T3… to obtain the theoretical total operating time T of the coupled thermal decomposition and hydrolysis hydrogen supply; Step 5: integrating and calculating the hydrogen-electric conversion efficiency based on the full-cycle theoretical operating time, and quantifying the hydrogen-electric conversion efficiency by the following formula: ； Hydrogen supply time = hydrogen production amount / V H2 ; Reaction Scheme (1): Reaction Scheme (2): ; Reaction Scheme (3): .

2. The hydrogen electro-conversion efficiency calculation method of claim 1, wherein, The fuel tank is provided with a reaction space, and the aluminum trihydride material in the reaction space is filled by mixing pressed tablets and powder, and the gaps between adjacent pressed tablets are filled with aluminum trihydride powder.

3. The hydrogen-to-electric conversion efficiency calculation method according to claim 1, characterized by, In the starting stage, the electronic control board controls the heating rod to be powered on to heat the stack; in the stable stage, the electronic control board controls the heating rod to be powered off, and the common fan is used to dissipate heat for the cathode tail gas flowing through the coupling device channel, and the rotating speed of the common fan is adjusted according to the information obtained by the temperature sensor.

4. The hydrogen-to-electric conversion efficiency calculation method according to claim 1, characterized by, The water recovery module further comprises a radiator and a water distributor, the first end of the radiator is in communication with the stack cathode tail gas outlet, the second end is in communication with the gas-liquid separator, and the radiator is used to cool the cathode tail gas; the water distributor has a multi-point irrigation structure, and a plurality of branch pipes are arranged along the height direction of the fuel tank and are uniformly distributed in the gaps between the aluminum trihydride pressed tablets in the fuel tank, and are used to uniformly spray the separated water delivered by the liquid pump.

5. The hydrogen-to-electric conversion efficiency calculation method according to claim 1, characterized by, The fuel tank electric heater is a membrane heater, which is arranged outside the fuel tank, and the membrane heater is provided with a fuel tank temperature sensor for real-time monitoring of the heating temperature and feedback to the electronic control board to control the heating temperature to be maintained at a preset temperature.

6. The hydrogen-to-electric conversion efficiency calculation method according to claim 1, characterized by, The solid-state hydrogen storage hydrogen supply module further comprises a pressure relief valve, one end of the pressure relief valve is in communication with the fuel tank, and the other end is in communication with the outside, and the pressure relief valve automatically releases pressure when the hydrogen pressure in the fuel tank exceeds a preset pressure.

7. The hydrogen-to-electric conversion efficiency calculation method according to claim 1, characterized by, The electric control unit further comprises a current sensor for monitoring the output current of the stack and a voltage sensor for monitoring the output voltage of the stack, and the electric control board calculates the total power of the stack and the net output power of the system according to the above-mentioned electric signals.

Images