A high-efficiency metal hydride hydrogen storage system for air-cooled fuel cell stacks

Abstract

This invention relates to the field of hydrogen supply, and in particular to a high-efficiency metal hydride hydrogen storage system for air-cooled fuel cell stacks. The system includes a first one-way plate fan, a cabinet, a first through-plate connector, a second through-plate connector, a third through-plate connector, a fourth through-plate connector, a hydrogen leak sensor, a tank support frame, heat exchange fins, a loop heat pipe, a metal hydride hydrogen storage tank (one or more metal hydride hydrogen storage tanks), a second one-way plate fan, a loop heat pipe heat exchanger, a heat exchange gas inlet, a fifth through-plate connector, a safety pressure relief valve, a first ball valve, a second ball valve, a pressure reducing valve, a third ball valve, a fourth ball valve, a fifth ball valve, a pressure sensor, a sixth ball valve, a temperature sensor, an exhaust vent, and a cabinet. This invention is highly applicable, reliable, and safe. It can efficiently purify and store hydrogen, and improve heat exchange efficiency without requiring additional energy consumption, thereby enhancing the heat and mass transfer of the metal hydride hydrogen storage tank and the hydrogen absorption and desorption performance of the internal hydrogen storage alloy.

Description

Technical Field

[0001] This invention relates to the field of hydrogen supply, and in particular to a high-efficiency metal hydride hydrogen storage system for air-cooled fuel cell stacks. Background Technology

[0002] In recent years, the world has faced a severe energy crisis due to the overexploitation of non-renewable energy sources. Hydrogen energy is renewable, clean, and safe. It can be produced using fossil fuels or through the hydrolysis of renewable energy sources. It is convenient to store and transport, and does not cause environmental pollution in transportation or heating. Through its role as an energy carrier and a circular carbon economy, sustainable hydrogen utilization can be achieved, greatly alleviating the current global energy crisis.

[0003] The hydrogen energy industry chain mainly includes upstream hydrogen production, midstream hydrogen storage and transportation, and downstream hydrogen fuel cells and their applications. Efficient and safe hydrogen storage is crucial for the realization of hydrogen energy. Hydrogen exists in a gaseous state under normal conditions and is flammable, explosive, and easily diffused, posing significant challenges to its storage and transportation. Hydrogen storage and transportation are mainly divided into three methods: gaseous, liquid, and solid. Solid-state hydrogen storage involves hydrogen storage alloys combining with hydrogen to store it as metal hydrides, which can be released under certain conditions. Solid-state hydrogen storage has certain advantages over high-pressure gaseous and liquid hydrogen storage. Firstly, solid-state hydrogen storage has a high volumetric hydrogen storage density. Among existing high-pressure gaseous, liquid, and solid hydrogen storage methods, solid-state hydrogen storage has the highest volumetric hydrogen storage density. For example, the volumetric hydrogen storage density of MgH2 can reach 106 kg / m³. 3 Solid-state hydrogen storage boasts several advantages. First, it has a density 1191 times that of hydrogen under standard conditions, 2.7 times that of hydrogen stored at 70 MPa high pressure, and 1.5 times that of liquid hydrogen. Second, it offers superior safety, storing hydrogen at ambient temperature and pressure. The storage tanks are easily sealed, and even in the event of a hydrogen leak, the tanks can automatically reduce the leakage rate and volume, buying valuable time for safety measures. Furthermore, solid-state hydrogen storage operates at lower pressures, eliminating the energy consumption required for high-pressure hydrogen compression and the investment costs associated with high-pressure hydrogen compressors. These advantages make solid-state hydrogen storage suitable for applications such as stationary hydrogen storage, peak-shaving and valley-filling hydrogen storage in power systems, and hydrogen fuel cell engineering vehicles.

[0004] However, metal hydride hydrogen storage alloys release or absorb a large amount of heat during hydrogen absorption and desorption. If this heat cannot be dissipated, the temperature of the hydrogen storage device will rapidly decrease or increase. The hydrogen absorption and desorption pressure of the alloy decreases with decreasing temperature. When the heat cannot be dissipated quickly, the alloy may cease to absorb or release hydrogen continuously. To avoid this, waste heat from the fuel cell is typically used to heat the hydrogen storage device to ensure hydrogen release. This is coupled with the thermal management system of an air-cooled fuel cell, using either air cooling or water cooling to cool the storage device. However, this approach suffers from low efficiency, complex coupling interfaces with the fuel cell, and the need for a water pump in water cooling systems, which consumes additional energy.

[0005] Therefore, there is an urgent need to design a high-efficiency heat and mass transfer metal hydride hydrogen storage system for air-cooled fuel cells to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to provide a high-efficiency metal hydride hydrogen storage system for air-cooled fuel cell stacks, which solves the problems of insufficient hydrogen absorption in the hydrogen storage alloy due to heat accumulation in the core of the metal hydride hydrogen storage tank during hydrogen absorption, and the inability of hydrogen to be released from the alloy due to excessively low material temperature in the center of the tank during hydrogen release.

[0007] The technical solution of this invention is:

[0008] A high-efficiency metal hydride hydrogen storage system for an air-cooled fuel cell stack includes a first through-plate connector whose inlet is connected to an external helium cylinder via a stainless steel pipe; an outlet of the first through-plate connector connected to the inlet of a fifth ball valve; an outlet of the fifth ball valve connected to the first port of a three-way connector; a second port of the three-way connector connected to a pressure sensor; a third port of the three-way connector connected to the first port of a four-way connector; a second port of the four-way connector connected to the outlet of a fourth ball valve; an inlet of the fourth ball valve connected to the outlet of a second through-plate connector; an inlet of the second through-plate connector connected to a hydrogen cylinder; a third port of the four-way connector connected to the inlet of the second ball valve; an outlet of the second ball valve connected to a first metal hydride hydrogen storage tank; and a fourth port of the four-way connector connected to the first port of a three-way connector. The second port of the connector is connected to the inlet of the third ball valve. The outlet of the third ball valve is connected to the inlet of the third through-plate connector. The outlet of the third through-plate connector is connected to the inlet of the vacuum pump. The third port of the three-way connector is connected to the first port of a four-way connector. The second port of the four-way connector is connected to the inlet of the sixth ball valve. The outlet of the sixth ball valve is connected to the inlet of the pressure reducing valve. The outlet of the pressure reducing valve is connected to the inlet of the fourth through-plate connector. The outlet of the fourth through-plate connector is connected to the inlet of the hydrogen demand device. The third port of the four-way connector is connected to the inlet of the safety relief valve. The outlet of the safety relief valve is connected to the inlet of the fifth through-plate connector. The outlet of the fifth through-plate connector faces directly to the atmosphere. The fourth port of the four-way connector is connected to the inlet of the first ball valve. The outlet of the first ball valve is connected to the second metal hydride hydrogen storage tank.

[0009] The high-efficiency metal hydride hydrogen storage system for the air-cooled fuel cell stack includes a first metal hydride hydrogen storage tank and a second metal hydride hydrogen storage tank, each connected to a loop heat pipe. Specifically, a portion of one loop heat pipe passes through the first metal hydride hydrogen storage tank, and another portion passes through a loop heat pipe heat exchanger; a portion of the other loop heat pipe passes through the second metal hydride hydrogen storage tank, and another portion passes through a loop heat pipe heat exchanger. The outer walls of the first and second metal hydride hydrogen storage tanks are fitted with heat exchange fins, which are tightly connected to the tank bodies of the first and second metal hydride hydrogen storage tanks using thermally conductive adhesive.

[0010] In the aforementioned high-efficiency metal hydride hydrogen storage system for air-cooled fuel cell stacks, the first metal hydride hydrogen storage tank and the second metal hydride hydrogen storage tank are placed at the center of the tank support frame. The heat exchange fins and the loop heat pipe heat exchanger on the outside of the first metal hydride hydrogen storage tank and the second metal hydride hydrogen storage tank are placed in the direction of the tank support frame toward the center of the air inlet, and the loop heat pipe heat exchanger is preferentially close to the direction of the air inlet.

[0011] The high-efficiency metal hydride hydrogen storage system for the air-cooled fuel cell stack also includes a cabinet. A first metal hydride hydrogen storage tank, a second metal hydride hydrogen storage tank, a loop heat pipe heat exchanger, and connecting pipes are housed within the cabinet. A first through-plate connector, a second through-plate connector, a third through-plate connector, and a fourth through-plate connector are mounted on one side panel of the cabinet. The cabinet is a rectangular frame with sloping sides on both sides. Air inlets and outlets are located at the front and rear of the cabinet, respectively. A first one-way fan and a second one-way fan are respectively installed on the sloping sides of the air inlet, and one-way air vanes are installed at the rear ends of the first and second one-way fans. The centers of the first and second one-way fans are aligned with the heat exchange fins of the loop heat pipe heat exchanger and the first and second metal hydride hydrogen storage tanks. A hydrogen leak sensor is installed at the top inside the cabinet.

[0012] The high-efficiency metal hydride hydrogen storage system for the air-cooled fuel cell stack has an air inlet size that matches the cooling and exhaust system of the air-cooled fuel cell stack. The exhaust outlet is perforated or grid-shaped, and the cabinet is made of aluminum, carbon steel, stainless steel, or alloy steel.

[0013] The high-efficiency metal hydride hydrogen storage system for the air-cooled fuel cell stack described above has the same structure for the first and second metal hydride hydrogen storage tanks. Both include a seventh ball valve, an NPT connector, a filter element, a porous stainless steel guide pipe, a hydrogen storage module, thermally conductive adhesive, heat transfer fins, a loop heat pipe, heat exchange fins, a tank body, and a hydrogen storage module. The specific structure is as follows:

[0014] The seventh ball valve is located outside the tank body. An NPT connector is provided at the end of the tank body. One end of the seventh ball valve is screwed to one end of the NPT connector through a pipeline. The external thread of one end of the pipeline corresponds to and matches the internal thread of one end of the NPT connector to form the threaded connection between the seventh ball valve and the NPT connector. The filter element is located on one side of the inner cavity of the tank body. The other end of the NPT connector extends into the inner cavity of the tank body and is fixed to one end of the filter element by welding through a Z-shaped stainless steel tube. A porous stainless steel guide tube is placed at the central axis inside the tank body. The porous stainless steel guide tube runs along the axis of the tank body to the bottom of the tank body. The other end of the filter element is inserted into the porous stainless steel guide tube. The hydrogen storage module is filled inside the tank body. The hydrogen storage module and the adjacent internal heat transfer fins are tightly bonded by a heat transfer powder layer. The porous stainless steel guide tube runs through the hydrogen storage module. The outer edge of the hydrogen storage module is clearance-fitted with the tank body to leave room for the hydrogen storage alloy to absorb hydrogen and expand.

[0015] The heat transfer fins are arranged parallel to each other on the inner side wall of the tank. Each heat transfer fin has a through hole in its center, and a porous stainless steel guide tube passes through the heat transfer fin through the through hole. In order to ensure that each heat transfer fin is in close contact with the inner side wall of the tank, thermally conductive adhesive is applied to the gap between the heat transfer fin and the inner side wall of the tank. The loop heat pipe is a closed pipe that passes through the tank. The loop heat pipe that is in direct contact with the heat exchange gas is provided with heat exchange fins. The heat exchange fins are bonded to the part of the loop heat pipe located on the outside of the tank by thermally conductive adhesive. The loop heat pipe heat exchanger is composed of the heat exchange fins.

[0016] The high-efficiency metal hydride hydrogen storage system for the air-cooled fuel cell stack includes a metal hydride hydrogen storage tank made of stainless steel or aluminum alloy with a diameter of 60-100 mm and a length of 200-2000 mm. The outer wall of the metal hydride hydrogen storage tank is fitted with heat exchange fins made of stainless steel, aluminum alloy, or copper alloy, with a fin height of 6-25 mm and a fin spacing of 5-10 mm, evenly distributed along the tank's axial direction. A porous stainless steel guide tube penetrates the through-holes of the heat exchange fins, with the through-hole diameter being 6-12 mm. The filter element is a metal tubular structure processed by powder metallurgy, with an inner diameter... The filter element has an average pore size of 1μm to 5μm and a porosity of 25% to 30%. The hydrogen storage module is a mixture of hydrogen storage alloy powder and expanded graphite, which fills the space between the internal heat transfer fins. The mass ratio of hydrogen storage material powder to expanded graphite in the mixture is 7:3 to 99:1. The hydrogen storage material powder is a titanium-based AB2 type hydrogen storage alloy, a rare earth-based AB5 type hydrogen storage alloy, a titanium-iron type hydrogen storage alloy, or a vanadium-based hydrogen storage alloy. The particle size range of the hydrogen storage material powder and expanded graphite is 0.2mm to 1.2mm.

[0017] The high-efficiency metal hydride hydrogen storage system for the air-cooled fuel cell stack has a first through hole and a second through hole at the center of the heat transfer fins for the passage of a porous stainless steel guide pipe and a loop heat pipe; the heat transfer fins are made of copper, aluminum or stainless steel, and the thickness of the heat transfer fins is 0.6mm to 1.2mm; the heat transfer fins have uniformly distributed packing holes along the circumference, and the packing holes are equidistantly distributed along the periphery of the heat transfer fins, with a diameter of 3mm to 6mm.

[0018] The aforementioned high-efficiency metal hydride hydrogen storage system for air-cooled fuel cell stacks comprises a loop heat pipe with one end located inside the metal hydride hydrogen storage tank and the other end located on a loop heat pipe heat exchanger on the side of the metal hydride hydrogen storage tank. The loop heat pipe heat exchanger is in direct contact with the heat exchange gas and is positioned higher than the loop heat pipe inside the metal hydride hydrogen storage tank. The inclination of the loop heat pipe is 5-15 degrees with respect to the horizontal plane. Each loop heat pipe consists of a shell, a wick, and a liquid. The inside of the loop heat pipe is evacuated to a negative pressure state. The shell is a seamless metal tube made of copper, aluminum, carbon steel, stainless steel, or alloy steel, and is a standard cylindrical shape. Inside the shell, there is a wick and a liquid. The wick is a capillary porous material woven from metal fibers, and the liquid used is acetone, ethanol, water, or toluene.

[0019] The aforementioned high-efficiency metal hydride hydrogen storage system for air-cooled fuel cell stacks, during hydrogen release, introduces cooling air from the fuel cell into the cabinet through the air inlet. The airflow flows sequentially through one end of the loop heat pipe and the first and second metal hydride hydrogen storage tanks. The heat carried by the gas passes through the heat exchange fins and loop heat pipe, transferring heat into the interior of the first and second metal hydride hydrogen storage tanks, thereby achieving rapid hydrogen release during the hydrogen release process. The released hydrogen then passes through the first... The first ball valve, the second ball valve, the sixth ball valve, and the pressure reducing valve supply hydrogen to the fuel cell. During hydrogen charging, the hydrogen source is connected to the second through-plate connector, the fourth ball valve is opened, and the first and second one-way plate fans on the side are opened simultaneously. This causes the one-way fan plates on the cabinet to open, blowing ambient air into the cabinet. The air carries away the heat generated by the metal hydride hydrogen storage device during hydrogen absorption. This heat is transferred to the gas through the heat exchange fins and the loop heat pipe, thereby achieving rapid hydrogen absorption of the metal hydride hydrogen storage tank.

[0020] The advantages and beneficial effects of this invention are:

[0021] 1. This invention utilizes a loop heat pipe installed inside the metal hydride hydrogen storage tank to rapidly import and export the heat generated during hydrogen absorption and the heat required during hydrogen release, thereby improving the stable hydrogen release time of the hydrogen storage system and reducing the time required for hydrogen absorption.

[0022] 2. This invention improves the heat transfer effect of the heat pipe by designing it as a loop and setting a certain inclination; at the same time, heat transfer fins are set on the outside of the loop heat pipe, which can efficiently exchange the heat of the heat exchange gas, thereby realizing efficient heat and mass transfer of the metal hydride hydrogen storage tank.

[0023] 3. This invention cools the metal hydride hydrogen storage tank by introducing exhaust gas from an air-cooled fuel cell into the metal hydride hydrogen storage system. Through a loop heat pipe, the hydrogen absorption and desorption performance of the metal hydride hydrogen storage tank is improved without requiring additional energy consumption. This avoids the need for circulating water pumps, heat exchangers, and other devices required for heating and cooling the metal using water cooling methods, thus avoiding energy consumption in the heat exchange process and reducing system weight and volume. Compared with direct air cooling, this significantly improves the heat and mass transfer performance of the metal hydride hydrogen storage tank, avoiding the problem of a significant decrease in system volumetric density and mass density caused by controlling the tank diameter too small to ensure air cooling effectiveness.

[0024] 4. This invention greatly improves the heat transfer efficiency inside the metal hydride hydrogen storage tank by fixing heat exchange fins to the outside of the metal hydride tank, ensuring that the alloy hydrogen storage tank can quickly absorb / release hydrogen.

[0025] 5. This invention, by incorporating heat transfer fins inside the metal hydride tank, distributes the hydrogen storage alloy powder within the tank into separate hydrogen storage modules. This prevents localized aggregation of the hydrogen storage material powder within the tank, ensuring its uniformity and avoiding stress concentration caused by hydrogen absorption and expansion, which could negatively impact the safety performance of the solid-state hydrogen storage tank. Simultaneously, the internal heat transfer fins also enhance the overall heat transfer performance of the metal hydride tank.

[0026] 6. This invention involves mixing and filling the interior of a metal hydride tank with hydrogen storage material powder and expanded graphite. Expanded graphite has excellent heat transfer characteristics, which can significantly improve heat transfer performance. Simultaneously, the porous structure of expanded graphite avoids stress concentration and compaction effects caused by the expansion of the hydrogen storage material during hydrogen absorption, thus preventing these effects from impacting the safety performance of the solid-state hydrogen storage tank and also avoiding the deterioration of hydrogen conduction caused by compaction.

[0027] 7. This invention utilizes a fan-cooled design in the casing to draw ambient air into the metal hydride hydrogen storage system during hydrogen absorption. This allows for efficient heat removal during the hydrogen absorption process and reduces the time required for system refilling.

[0028] 8. This invention achieves rapid hydrogen input and output by setting short filter elements at the inlet and outlet of the metal hydride tank and setting a porous stainless steel guide tube in the center. At the same time, it can prevent the hydrogen storage material powder from flowing out of the system with the hydrogen when releasing hydrogen, thereby preventing damage to valves and gas lines. Compared with the use of through-type filter elements, it reduces costs.

[0029] 9. This invention is equipped with a pressure gauge, a safety relief valve, and a hydrogen leakage monitoring device, which facilitates real-time monitoring of the pressure inside the alloy hydrogen storage tank while preventing hydrogen overpressure events. At the same time, it monitors hydrogen leakage, thereby improving the safety of the system. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of a high-efficiency metal hydride hydrogen storage system for an air-cooled fuel cell stack according to an embodiment of the present invention.

[0031] Figure 2 This is a schematic diagram of the internal structure of a tank in a high-efficiency metal hydride hydrogen storage system for an air-cooled fuel cell stack according to an embodiment of the present invention.

[0032] Figure 3 This is a schematic diagram of the internal heat transfer fins of a tank in a high-efficiency metal hydride hydrogen storage system for an air-cooled fuel cell stack according to an embodiment of the present invention.

[0033] Figure 4 This is a schematic diagram of the loop heat pipe installation of a high-efficiency metal hydride hydrogen storage system for an air-cooled fuel cell stack according to an embodiment of the present invention.

[0034] Figure 5 This is a schematic diagram of the purging process of a high-efficiency metal hydride hydrogen storage system for an air-cooled fuel cell stack according to an embodiment of the present invention.

[0035] Figure 6 This is a schematic diagram of the hydrogen charging process for a high-efficiency metal hydride hydrogen storage system for an air-cooled fuel cell stack, as described in an embodiment of the present invention.

[0036] Figure 7 This is a schematic diagram of the hydrogen release process of a high-efficiency metal hydride hydrogen storage system for an air-cooled fuel cell stack according to an embodiment of the present invention.

[0037] In the diagram: 1 First unidirectional plate fan, 2 Cabinet, 3 First through-panel connector, 4 Second through-panel connector, 5 Third through-panel connector, 6 Fourth through-panel connector, 7 Hydrogen leak sensor, 8 Tank support frame, 9 Heat exchange fins, 10 Loop heat pipe, 11 First metal hydride hydrogen storage tank, 12 Second unidirectional plate fan, 13 Loop heat pipe heat exchanger, 14 Air inlet, 15 Fifth through-panel connector, 16 Safety relief valve, 17 First ball valve, 18 Second ball valve, 19 Pressure reducing valve, 20 Third ball valve, 21 Fourth ball valve, 22 Fifth ball valve, 23 Second metal hydride hydrogen storage tank, 24 Pressure sensor, 25 Sixth ball valve, 26 Temperature sensor, 27 Exhaust vent, 28 Cabinet.

[0038] 11-1. Seventh ball valve; 11-2. NPT connector; 11-3. Filter element; 11-4. Porous stainless steel guide tube; 11-5. Hydrogen storage module; 11-6. Thermally conductive adhesive; 11-7. Heat transfer fins; 11-8. Loop heat pipe; 11-9. Heat exchange fins; 11-10. Tank body; 11-11. Packing holes; 11-12. First through hole; 11-13. Second through hole. Detailed Implementation

[0039] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0040] like Figures 1-4 As shown, this invention proposes a high-efficiency metal hydride hydrogen storage system for air-cooled fuel cell stacks, mainly comprising: a first one-way plate fan 1, a cabinet 2, a first through-plate connector 3, a second through-plate connector 4, a third through-plate connector 5, a fourth through-plate connector 6, a hydrogen leak sensor 7, a tank support frame 8, heat exchange fins 9, a loop heat pipe 10, a metal hydride hydrogen storage tank (one or more metal hydride hydrogen storage tanks), a second one-way plate fan 12, a loop heat pipe heat exchanger 13, an air inlet 14, a fifth through-plate connector 15, a safety pressure relief valve 16, a first ball valve 17, a second ball valve 18, a pressure reducing valve 19, a third ball valve 20, a fourth ball valve 21, a fifth ball valve 22, a pressure sensor 24, a sixth ball valve 25, a temperature sensor 26, an exhaust port 27, and a cabinet 28. The specific structure is as follows:

[0041] like Figure 1As shown, the inlet of the first through-plate connector 3 is connected to a commercially available helium cylinder via a stainless steel pipe. The outlet of the first through-plate connector 3 is connected to the inlet of the fifth ball valve 22. The outlet of the fifth ball valve 22 is connected to the first port of a three-way connector. The second port of the three-way connector is connected to a pressure sensor 24. The third port of the three-way connector is connected to the first port of a four-way connector. The second port of the four-way connector is connected to the outlet of the fourth ball valve 21. The inlet of the fourth ball valve 21 is connected to the outlet of the second through-plate connector 4. The inlet of the second through-plate connector 4 is connected to a commercially available hydrogen cylinder. The third port of the four-way connector is connected to the inlet of the second ball valve 18. The outlet of the second ball valve 18 is connected to the first metal hydride hydrogen storage tank 11. The fourth port of the four-way connector is connected to the first port of a three-way connector. The second port of the three-way connector is connected to the inlet of the third ball valve 20. The outlet of the third ball valve 20 is connected to the inlet of the third through-plate connector 5. The outlet of the third through-plate connector 5 is connected to a vacuum pump. At the inlet, a vacuum pump extracts the waste gas from the entire system, setting the system to a vacuum state initially. The third port of the three-way connector is connected to the first port of a four-way connector. The second port of the four-way connector is connected to the inlet of the sixth ball valve 25. The outlet of the sixth ball valve 25 is connected to the inlet of the pressure reducing valve 19, which can be set to the required gas pressure. The outlet of the pressure reducing valve 19 is connected to the inlet of the fourth through-plate connector 6, and the outlet of the fourth through-plate connector 6 is connected to the inlet of the hydrogen demand device. The third port of the four-way connector is connected to the inlet of the safety relief valve 16, and the outlet of the safety relief valve 16 is connected to the inlet of the fifth through-plate connector 15. The outlet of the fifth through-plate connector 15 faces directly to the atmosphere. When the pressure sensor detects that the pressure inside the system is greater than 15 MPa, the safety relief valve 16 is activated to directly discharge the excess gas. The fourth port of the four-way connector is connected to the inlet of the first ball valve 17, and the outlet of the first ball valve 17 is connected to the second metal hydride hydrogen storage tank 23. The commercially available helium and hydrogen cylinders contain high-purity gas with a full capacity of 40L, a pressure of 15 MPa, and a volume concentration of 99.999%. The gas path connections of the valves, connectors, and tanks within the system are made using welded 316 stainless steel pipes.

[0042] The first metal hydride hydrogen storage tank 11 and the second metal hydride hydrogen storage tank 23 are respectively connected to the loop heat pipe 10, wherein: a part of one loop heat pipe 10 passes through the first metal hydride hydrogen storage tank 11, and another part of the loop heat pipe 10 passes through the loop heat pipe heat exchanger 13; a part of the other loop heat pipe 10 passes through the second metal hydride hydrogen storage tank 23, and another part of the loop heat pipe 10 passes through the loop heat pipe heat exchanger 13. The outer walls of the first metal hydride hydrogen storage tank 11 and the second metal hydride hydrogen storage tank 23 are fitted with heat exchange fins 9. Commercially available thermally conductive adhesive is used to tightly connect the heat exchange fins 9 to the tank bodies of the first metal hydride hydrogen storage tank 11 and the second metal hydride hydrogen storage tank 23. The first metal hydride hydrogen storage tank 11 and the second metal hydride hydrogen storage tank 23 are placed at the center of the tank support frame 8 to increase the heat exchange area. The heat exchange fins 9 on the outside of the first metal hydride hydrogen storage tank 11 and the second metal hydride hydrogen storage tank 23 and the loop heat pipe heat exchanger 13 are placed on the tank support frame 8 facing the center of the air inlet 14. The loop heat pipe heat exchanger 13 is preferentially close to the air inlet 14 to enable the interior of the metal hydride hydrogen storage tank to cool or heat rapidly.

[0043] Cabinet 2 includes cabinet 28, exhaust vent 27, air inlet 14, first one-way fan 1, hydrogen leak sensor 7, second one-way fan 12, first metal hydride hydrogen storage tank 11, second metal hydride hydrogen storage tank 23, loop heat pipe heat exchanger 13, and connecting pipelines, all housed within cabinet 28. First through-panel connector 3, second through-panel connector 4, third through-panel connector 5, and fourth through-panel connector 6 are mounted on one side panel of cabinet 28. Cabinet 28 is a rectangular frame with beveled sides on both sides of the front. Air inlet 14 and air outlet 27 are located at the front and rear of cabinet 28, respectively. A first one-way fan 1 and a second one-way fan 12 are respectively installed on the diagonal sides of air inlet 14 on both sides of cabinet 28. One-way air deflectors are installed at the rear ends of the first one-way fan 1 and the second one-way fan 12. When the hydrogen concentration inside cabinet 2 approaches 30,000 ppm, the first one-way fan 1 and the second one-way fan 12 start up, quickly discharging excess hydrogen from cabinet 2 into the surrounding environment. The centers of the first one-way fan 1 and the second one-way fan 12 are aligned with the heat exchange fins of the loop heat pipe heat exchanger 13 and the first metal hydride hydrogen storage tank 11 and the second metal hydride hydrogen storage tank 23. The hydrogen leakage sensor 7 is located on the top inside cabinet 28, enabling more accurate detection of hydrogen leakage concentration. The size of the air inlet 14 can be matched with the cooling exhaust system of the air-cooled fuel cell stack. The exhaust port 27 can be perforated or grid-like. The material of the cabinet 28 can be aluminum, carbon steel, stainless steel or alloy steel, etc.

[0044] During hydrogen release, cooling air from the fuel cell is introduced into the cabinet 28 through the air inlet 14. The airflow flows successively through one end of the loop heat pipe 10 and the first metal hydride hydrogen storage tank 11 and the second metal hydride hydrogen storage tank 23. The heat carried by the gas passes through the heat exchange fins 11-9 and the loop heat pipe 10, and the heat is introduced into the interior of the first metal hydride hydrogen storage tank 11 and the second metal hydride hydrogen storage tank 23, thereby realizing the rapid release of hydrogen during the hydrogen release process of the metal hydride hydrogen storage tank. The released hydrogen passes through the tank valves (first ball valve 17, second ball valve 18), the outlet valve (sixth ball valve 25), and the pressure reducing valve 19 before being supplied to the fuel cell. During hydrogen charging, connect the hydrogen gas source to the hydrogen inlet (second through-plate connector 4), open the hydrogen inlet valve (fourth ball valve 21), and simultaneously turn on the side hydrogen absorption and heat dissipation fans (first one-way plate fan 1 and second one-way plate fan 12) to blow open the one-way fan plate on the cabinet 28, blowing the ambient gas into the cabinet 28. The gas carries away the heat generated by the metal hydride hydrogen storage device during hydrogen absorption. This heat is transferred to the gas through the heat exchange fins and the loop heat pipe, thereby realizing the rapid hydrogen absorption of the metal hydride hydrogen storage tank.

[0045] like Figures 1-2 As shown, the first metal hydride hydrogen storage tank 11 includes a seventh ball valve 11-1 (gas valve), an NPT connector 11-2, a filter element 11-3, a porous stainless steel guide pipe 11-4, a hydrogen storage module 11-5, thermally conductive adhesive 11-6, heat transfer fins 11-7, a loop heat pipe 11-8, heat exchange fins 11-9, a tank body 11-10, and packing holes 11-11. The structure of the second metal hydride hydrogen storage tank 23 is the same as that of the first metal hydride hydrogen storage tank 11, and the specific structure is as follows:

[0046] The seventh ball valve 11-1 is located outside the tank body 11-10. An NPT connector 11-2 is located at the end of the tank body 11-10. One end of the seventh ball valve 11-1 is threaded to one end of the NPT connector 11-2 via a pipe. The external thread of one end of the pipe corresponds to and matches the internal thread of one end of the NPT connector 11-2, forming the threaded connection between the seventh ball valve 11-1 and the NPT connector. The filter element 11-3 is located on one side of the inner cavity of the tank body 11-10. The other end of the NPT connector 11-2 extends into the inner cavity of the tank body 11-10 and is fixed to one end of the filter element 11-3 by welding via a Z-shaped stainless steel pipe. A porous stainless steel guide pipe 11... -4 is placed at the central axis inside the tank 11-10. The porous stainless steel guide tube 11-4 runs along the axis of the tank 11-10 to the bottom of the tank 11-10. The other end of the filter element 11-3 is inserted into the porous stainless steel guide tube 11-4. The hydrogen storage module 11-5 is filled inside the tank 11-10. The hydrogen storage module 11-5 is a mixture of hydrogen storage alloy powder and expanded graphite. The hydrogen storage module 11-5 and the adjacent internal heat transfer fins 11-7 are tightly bonded by the heat transfer powder layer. The porous stainless steel guide tube 11-4 runs through the hydrogen storage module 11-5. The outer edge of the hydrogen storage module 11-5 is fitted with the tank 11-10 with a gap to leave room for the hydrogen storage alloy to absorb hydrogen and expand.

[0047] Heat transfer fins 11-7 are arranged parallel to each other on the inner wall of the tank 11-10. A through hole is opened in the center of each heat transfer fin 11-7, and a porous stainless steel guide tube 11-4 passes through the through hole to penetrate the heat transfer fin 11-7. In order to ensure that each heat transfer fin 11-7 is in close contact with the inner wall of the tank 11-10, thermally conductive adhesive 11-6 needs to be applied to the gap between the heat transfer fin 11-7 and the inner wall of the tank 11-10 to ensure rapid heat conduction between the heat transfer fin 11-7 and the tank 11-10, thereby improving the hydrogen absorption and desorption rate of the metal hydride hydrogen storage device, improving the heat transfer performance, and fixing the heat transfer fins 11-7. The loop heat pipe 11-8 is a closed pipe that passes through the tank 11-10. The loop heat pipe 11-8, which is in direct contact with the heat exchange gas, is provided with heat exchange fins 11-9. The heat exchange fins 11-9 are bonded to the part of the loop heat pipe 11-8 located outside the tank 11-10 by thermally conductive adhesive. The loop heat pipe heat exchanger 13 is formed by the combination of heat exchange fins 11-9.

[0048] The metal hydride hydrogen storage tank can be made of stainless steel or aluminum alloy, etc., and the number of metal hydride hydrogen storage tanks can be 1 to 9, with an inner diameter of 60 to 100 mm and a length of 200 to 2000 mm. The outer wall of the metal hydride hydrogen storage tank is fitted with heat exchange fins, made of stainless steel, aluminum alloy, or copper alloy, with a fin height of 6 to 25 mm and a fin spacing of 5 to 10 mm, uniformly distributed along the axial direction of the tank. A porous stainless steel guide tube passes through the through-holes of the heat exchange fins, with the through-hole diameter being 6 to 12 mm. The filter element is a metal tubular structure processed by powder metallurgy, with an inner diameter of 3 mm to 5 mm, an average pore size of 1 μm to 5 μm, and a porosity of 25 to 30%. A mixture of hydrogen storage alloy powder and expanded graphite fills the space between the internal heat exchange fins, with the mass ratio of hydrogen storage material powder to expanded graphite in the mixture being 7:3 to 99:1. The hydrogen storage material powder can be titanium-based AB2 type hydrogen storage alloy, rare earth-based AB5 type hydrogen storage alloy, titanium-iron type hydrogen storage alloy or vanadium-based hydrogen storage alloy, and the particle size range of the hydrogen storage material powder and expanded graphite is 0.2mm~1.2mm.

[0049] like Figure 3 As shown, the internal heat transfer fins 11-7 of the metal hydride hydrogen storage tank 11 have a first through hole 11-12 and a second through hole 11-13 at their center, for the passage of the porous stainless steel guide pipe 11-4 and the loop heat pipe 11-8. The heat transfer fins 11-7 are made of copper, aluminum, or stainless steel, and their thickness is 0.6mm to 1.2mm. The heat transfer fins 11-7 have uniformly distributed packing holes 11-11 along their circumference, with a diameter of 3mm to 6mm.

[0050] like Figure 4 As shown, combined with Figure 2 It can be seen that a section of the loop heat pipe 11-8 is arranged inside the metal hydride hydrogen storage tank 11, and the loop heat pipe 11-8 (equivalent to Figure 1 , Figure 4Another section of the loop heat pipe 10 is arranged on the side of the metal hydride hydrogen storage tank 11 as a loop heat pipe heat exchanger 13. The loop heat pipe heat exchanger 13 is in direct contact with the heat exchange gas and is slightly higher than the loop heat pipe 10 placed inside the metal hydride hydrogen storage tank 11. The inclination angle of the loop heat pipe 10 to the horizontal plane is 5 to 15 degrees, which can accelerate the natural reflux of the liquid inside the loop heat pipe. There are one or more loop heat pipes 10. Each loop heat pipe 10 (or loop heat pipes 11-8) consists of a shell, a wick, and liquid. The inside of the loop heat pipe is evacuated to a negative pressure state. The shell is a seamless metal tube, which can be made of copper, aluminum, carbon steel, stainless steel, or alloy steel, etc., and the shell shape is a standard cylinder. The shell contains a wick and liquid. The wick is a capillary porous material woven from metal fibers. The liquid used can be acetone, ethanol, water, or toluene, etc.

[0051] like Figure 5 As shown, the present invention proposes a purging process for a high-efficiency metal hydride hydrogen storage system for air-cooled fuel cell stacks as follows:

[0052] The user must perform internal cleaning of the entire system. Using a commercially available helium cylinder, connect the system's first through-plate connector 3 via a stainless steel pipe, adjust its output pressure to 1 MPa, and open the fifth ball valve 22, the first ball valve 17, and the second ball valve 18 to begin charging the system. After charging is complete, close the fifth ball valve 22. Then, every minute, open the third ball valve 20 for approximately 10 seconds and then close it. Check that the pressure sensor 24 reads 0.1 MPa. Connect the vacuum pump to the third through-plate connector 5 and pump air for half an hour. When the pressure sensor 24 reading approaches vacuum, further close all valves, remove the vacuum pump, and the system purging is complete.

[0053] like Figure 6 As shown, the present invention proposes a hydrogen charging process for a high-efficiency metal hydride hydrogen storage system for air-cooled fuel cell stacks as follows:

[0054] When filling the entire system with hydrogen, the user selects a low-pressure hydrogen cylinder from the laboratory. Connect the system's second through-plate connector 4 via a stainless steel pipe, and open the fourth ball valve 21, the first ball valve 17, and the second ball valve 18. The metal hydride storage tank 11 begins to absorb hydrogen. Turn on the first one-way fan 1 and the second one-way fan 12 to expel heat from inside the cabinet 2, and monitor the readings of the pressure sensor 24 and temperature sensor 26. After filling is complete, close all valves in the system; at this point, the hydrogen filling is finished.

[0055] like Figure 7 As shown, the present invention proposes a hydrogen release process for a high-efficiency metal hydride hydrogen storage system for air-cooled fuel cell stacks as follows:

[0056] When the user discharges hydrogen using the system, the fuel cell outlet is placed close to the air inlet 14 installed in cabinet 2, the fourth through-plate connector 6 is connected to the fuel cell inlet, the output pressure of the pressure reducing valve 19 is adjusted, and the sixth ball valve 25 is opened to discharge hydrogen. During fuel cell operation, the readings of pressure sensor 24 and temperature sensor 26 are simultaneously monitored. When the pressure sensor 24 drops to the specified pressure or the hydrogen discharge time reaches the set time, all valves are closed, at which point the system's hydrogen discharge is complete.

[0057] The results show that the present invention is highly applicable, reliable and safe, and can efficiently purify and store hydrogen. It also improves heat exchange efficiency without requiring additional energy consumption, thereby enhancing the heat and mass transfer of the metal hydride hydrogen storage tank and the hydrogen absorption and desorption performance of the internal hydrogen storage alloy.

Claims

1. A high efficiency metal hydride hydrogen storage system for air breathing fuel cell stacks, characterized by, The gas inlet of the first through-plate joint is connected with the outside helium bottle through a stainless steel pipe, the gas outlet of the first through-plate joint is connected with the gas inlet of the fifth ball valve, the outlet end of the fifth ball valve is connected with the first port of a three-way joint, the second port of the three-way joint is connected with a pressure sensor, the third port of the three-way joint is connected with the first port of a four-way joint, the second port of the four-way joint is connected with the gas outlet of the fourth ball valve, the gas inlet of the fourth ball valve is connected with the gas outlet of the second through-plate joint, the gas inlet of the second through-plate joint is connected with the hydrogen bottle; the third port of the four-way joint is connected with the gas inlet of the second ball valve, the gas outlet of the second ball valve is connected with the first metal hydride hydrogen storage tank, the fourth port of the four-way joint is connected with the first port of a three-way joint; the second port of the three-way joint is connected with the gas inlet of the third ball valve, the gas outlet of the third ball valve is connected with the gas inlet of the third through-plate joint, the gas outlet of the third through-plate joint is connected with the gas inlet of the vacuum pump, the third port of the three-way joint is connected with the first port of a four-way joint, the second port of the four-way joint is connected with the gas inlet of the sixth ball valve, the gas outlet of the sixth ball valve is connected with the gas inlet of the pressure reducing valve, the gas outlet of the pressure reducing valve is connected with the gas inlet of the fourth through-plate joint, the gas outlet of the fourth through-plate joint is connected with the gas inlet of the hydrogen demand device, the third port of the four-way joint is connected with the gas inlet of the safety relief valve, the gas outlet of the safety relief valve is connected with the gas inlet of the fifth through-plate joint, the gas outlet of the fifth through-plate joint is directly connected with the atmosphere, the fourth port of the four-way joint is connected with the gas inlet of the first ball valve, the gas outlet of the first ball valve is connected with the second metal hydride hydrogen storage tank; The first metal hydride hydrogen storage tank and the second metal hydride hydrogen storage tank are respectively connected with a loop heat pipe, wherein: one part of the loop heat pipe penetrates through the first metal hydride hydrogen storage tank, and the other part of the loop heat pipe penetrates through the loop heat pipe heat exchanger; one part of the other loop heat pipe penetrates through the second metal hydride hydrogen storage tank, and the other part of the loop heat pipe penetrates through the loop heat pipe heat exchanger; the outer wall of the first metal hydride hydrogen storage tank and the second metal hydride hydrogen storage tank is sleeved with heat exchange fins, and the heat exchange fins are tightly connected with the tank bodies of the first metal hydride hydrogen storage tank and the second metal hydride hydrogen storage tank by using heat-conducting glue; A cabinet body is further provided, the first metal hydride hydrogen storage tank, the second metal hydride hydrogen storage tank, the loop heat pipe heat exchanger and the connected pipelines are arranged in the cabinet body, the first through-plate joint, the second through-plate joint, the third through-plate joint and the fourth through-plate joint are installed on one side plate of the cabinet body, the cabinet body is provided with inclined edge structures on the front sides of the cuboid frame, the air inlet and the air outlet are respectively arranged on the front and rear of the cabinet body, the size of the air inlet is matched with the cooling and exhaust system of the air-cooled fuel cell stack, the first one-way plate fan and the second one-way plate fan are respectively arranged on the inclined edges on the two sides of the air inlet of the cabinet body, and the one-way air plate is respectively arranged at the rear end of the first one-way plate fan and the second one-way plate fan; the first one-way plate fan and the second one-way plate fan are centrally aligned with the heat exchange fins of the loop heat pipe heat exchanger, the first metal hydride hydrogen storage tank and the second metal hydride hydrogen storage tank, the hydrogen leakage sensor is arranged on the top of the inner side of the cabinet body.

2. The efficient metal hydride hydrogen storage system for air-breathing fuel cell stacks according to claim 1, characterized in that, The first metal hydride hydrogen storage tank and the second metal hydride hydrogen storage tank are arranged in the center of the tank body support frame, the heat exchange fins and the loop heat pipe heat exchanger outside the first metal hydride hydrogen storage tank and the second metal hydride hydrogen storage tank are arranged in the direction of the center of the air inlet of the tank body support frame, and the loop heat pipe heat exchanger is arranged close to the direction of the air inlet.

3. The efficient metal hydride hydrogen storage system for air-breathing fuel cell stack as claimed in claim 1 wherein, The air outlet is a hole or a grating, and the cabinet body is made of aluminum, carbon steel, stainless steel or alloy steel.

4. The efficient metal hydride hydrogen storage system for air-breathing fuel cell stacks of claim 1, wherein, The first metal hydride hydrogen storage tank and the second metal hydride hydrogen storage tank have the same structure and comprise a seventh ball valve, an NPT joint, a filter element, a porous stainless steel flow guide pipe, a hydrogen storage module, heat-conducting glue, heat transfer fins, a loop heat pipe, heat exchange fins and a tank body. The seventh ball valve is arranged outside the tank body, the tank body is provided with an NPT joint at the end, one end of the seventh ball valve is screwed with one end of the NPT joint through a pipeline, the outer thread of one end of the pipeline corresponds to and matches the inner thread of one end of the NPT joint to form a threaded connection position of the seventh ball valve and the NPT joint, and the threaded connection position is screwed, the filter element is arranged on one side of the inner cavity of the tank body, the other end of the NPT joint extends into the inner cavity of the tank body and is fixedly connected with one end of the filter element through a Z-shaped stainless steel pipe in a welded manner, the porous stainless steel flow guide pipe is arranged at the central axis inside the tank body, the porous stainless steel flow guide pipe penetrates the tank body along the axis to the bottom of the tank body, and the other end of the filter element is inserted into the porous stainless steel flow guide pipe; the hydrogen storage module is filled in the tank body, the hydrogen storage module and the adjacent internal heat transfer fins are tightly attached through a heat transfer powder layer, the porous stainless steel flow guide pipe penetrates the hydrogen storage module, and the outer edge of the hydrogen storage module is gap-fitted with the tank body to leave space for the hydrogen storage alloy to absorb hydrogen and expand; The heat transfer fins are arranged in parallel on the inner side wall of the tank body, a through hole is formed in the center of each heat transfer fin, and the porous stainless steel flow guide pipe penetrates the heat transfer fins through the through hole; in order to ensure that each heat transfer fin is tightly attached to the inner side wall of the tank body, heat-conducting glue needs to be coated at the gap between the heat transfer fins and the inner side wall of the tank body; the loop heat pipe is a closed pipeline penetrating the tank body, and the loop heat pipe directly contacting the heat exchange gas is provided with heat exchange fins outside, the heat exchange fins are adhered to the part of the loop heat pipe located outside the tank body through heat-conducting glue, and the heat exchange fins are combined to form a loop heat pipe heat exchanger.

5. The efficient metal hydride hydrogen storage system for air-breathing fuel cell stacks of claim 4, wherein, The tank body material of the metal hydride hydrogen storage tank is stainless steel or aluminum alloy, with a diameter of 60-100 mm and a length of 200-2000 mm; the outer wall of the metal hydride hydrogen storage tank is sleeved with heat exchange fins, the heat exchange fins are made of stainless steel, aluminum alloy or copper alloy, the fin height is 6-25 mm, the fin spacing is 5-10 mm, and the heat exchange fins are uniformly distributed along the axial direction of the tank body; the porous stainless steel flow guide pipe penetrates through the through hole of the heat transfer fin, and the through hole diameter is 6-12 mm; the filter core is a metal tubular structure processed by powder metallurgy, the inner diameter of the filter core is 3-5 mm, the average pore size of the filter core is 1-5 um, and the porosity is 25-30%; the hydrogen storage module is a mixture of hydrogen storage alloy powder and expanded graphite, the hydrogen storage alloy powder and expanded graphite mixture is filled in the space between the internal heat transfer fins, the mass ratio of the hydrogen storage material powder to the expanded graphite in the hydrogen storage alloy powder and expanded graphite mixture is 7:3-99:1, the hydrogen storage material powder is titanium-based AB2 type hydrogen storage alloy, rare earth-based AB5 type hydrogen storage alloy, titanium-iron-based hydrogen storage alloy or vanadium-based hydrogen storage alloy, and the particle size of the hydrogen storage material powder and expanded graphite is 0.2-1.2 mm.

6. The efficient metal hydride hydrogen storage system for air-breathing fuel cell stack as claimed in claim 4 wherein, A first through hole and a second through hole are formed in the center of the heat transfer fin for the porous stainless steel flow guide pipe and the loop heat pipe to pass through; the heat transfer fin is a copper sheet, an aluminum sheet or a stainless steel sheet, and the thickness of the heat transfer fin is 0.6-1.2 mm; a plurality of filler holes are uniformly formed on the circumference of the heat transfer fin, the filler holes are equally distributed along the periphery of the heat transfer fin, and the diameter of the filler holes is 3-6 mm.

7. The efficient metal hydride hydrogen storage system for air-breathing fuel cell stack as claimed in claim 4 wherein, One section of the loop heat pipe is arranged inside the metal hydride hydrogen storage tank, and the other section of the loop heat pipe is arranged in the loop heat pipe heat exchanger on the side of the metal hydride hydrogen storage tank; the loop heat pipe heat exchanger is in direct contact with the heat exchange gas, and the loop heat pipe is higher than the loop heat pipe arranged in the metal hydride hydrogen storage tank; the inclination of the loop heat pipe is 5-15 degrees with the horizontal plane; each loop heat pipe is composed of a pipe shell, a wick and a liquid, the inside of the loop heat pipe is in a negative pressure state, the pipe shell is a metal seamless pipe, the material is copper, aluminum, carbon steel, stainless steel or alloy steel, and the shape of the pipe shell is a standard cylinder; the pipe shell is provided with a wick and a liquid, the wick is a capillary porous material made of metal fiber, and the liquid used is acetone, ethanol, water or toluene.

8. The efficient metal hydride hydrogen storage system for air-breathing fuel cell stack as claimed in claim 4 wherein, When hydrogen is released, the cooling air of the fuel cell is introduced into the cabinet through the air inlet, and the air flows through one end of the loop heat pipe and the first and second metal hydride hydrogen storage tanks. The heat carried by the air is transferred to the inside of the first and second metal hydride hydrogen storage tanks through the heat exchange fins and the loop heat pipe, so that the hydrogen is quickly released during the hydrogen release process of the metal hydride hydrogen storage tank. The released hydrogen is supplied to the fuel cell after passing through the first, second, sixth ball valves and the pressure reducing valve; when hydrogen is charged, the hydrogen source is connected to the second through plate joint, the fourth ball valve is opened, and the first and second one-way plate fans are opened to blow the one-way air plate on the cabinet to open, so that the gas in the external environment is blown into the cabinet. The heat generated by the metal hydride hydrogen storage device during the hydrogen absorption process is carried away by the gas, and the heat is transferred to the gas through the heat exchange fins and the loop heat pipe, so that the metal hydride hydrogen storage tank quickly absorbs hydrogen.

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