Metal hydride hydrogen storage device based on finned multilayer spiral heat pipe and thermal management method

Abstract

This invention discloses a metal hydride hydrogen storage device and thermal management method based on finned multilayer spiral heat pipes, belonging to the field of solid-state hydrogen storage technology. The device includes: a heat exchanger, a hydrogen storage reactor tank, and at least two sets of spiral heat pipes with different diameters. The hydrogen storage reactor tank is filled with a hydrogen storage alloy, and the spiral heat pipes are arranged coaxially in a nested manner to form a multilayer spiral heat pipe structure. One end of the multilayer spiral heat pipe structure is embedded inside the hydrogen storage alloy bed, and the other end extends to the outside of the tank and communicates with the heat exchanger. The outer wall of the tube section inside the bed has spiral fins; the outer wall of the tube section inside the heat exchanger has annular fins. During hydrogen absorption, the heat pipe section inside the bed is the evaporation section, and the section inside the heat exchanger is the condensation section; during hydrogen release, the two can be reversibly switched. This invention achieves uniform bed temperature distribution and efficient bidirectional thermal management for hydrogen absorption and release, while avoiding the risk of heat exchange fluid leakage, thus improving system safety and stability.

Description

Technical Field

[0001] This invention belongs to the field of solid-state hydrogen storage technology, specifically relating to a metal hydride hydrogen storage device and thermal management method based on a finned multilayer spiral heat pipe. Background Technology

[0002] Hydrogen energy, as a clean and efficient secondary energy source, is a key carrier for achieving energy structure transformation and the "dual-carbon" goal. Safe and efficient hydrogen storage technology is one of the core bottlenecks for the large-scale application of hydrogen energy. Among various hydrogen storage methods, solid-state hydrogen storage using metal hydrides has become a current research hotspot due to its advantages such as high volumetric hydrogen storage density, good safety, and mild operating conditions.

[0003] The essence of metal hydride hydrogen storage lies in the reversible chemical reaction between the metal or alloy and hydrogen: heat is released during hydrogen absorption and heat is absorbed during hydrogen release. Thermal management of metal hydride (MH) hydrogen storage systems is one of the key factors ensuring the hydrogen absorption and desorption performance of MH systems. However, the low effective thermal conductivity of MH materials poses a significant challenge to heat transfer. During the reversible hydrogen absorption and desorption reaction of metal hydrides, a large amount of heat exchange occurs, leading to uneven temperature distribution within the reactor and affecting its hydrogen storage performance and lifespan. Therefore, thermal management of the reaction bed is a core issue affecting the performance of hydrogen storage devices. An ideal hydrogen storage reactor needs to possess efficient heat removal (during hydrogen absorption) and heat import (during hydrogen release) capabilities to maintain uniform temperature in the reaction bed, thereby ensuring the kinetic performance of hydrogen absorption / desorption.

[0004] Existing metal hydride hydrogen storage devices mainly suffer from the following technical problems in terms of thermal management:

[0005] (1) Traditional reactors typically use internal heat exchange coils or jacketed heat exchange, with the heat exchange fluid directly introduced into the reactor. This structure carries the risk of heat exchange fluid leakage. Once a leak occurs, it will not only contaminate the hydrogen storage alloy, causing irreversible degradation of its performance, but may also lead to safety hazards.

[0006] (2) Due to the low thermal conductivity of metal hydride beds, traditional heat exchange structures are difficult to achieve uniform temperature distribution in the radial and axial directions, which can easily lead to local overheating or undercooling regions, resulting in uneven hydrogen absorption / desorption reaction rates and sluggish reaction kinetics, which seriously affect the hydrogen charging and desorption efficiency and cycle stability of hydrogen storage devices.

[0007] (3) Although there are existing technologies that use heat pipes for heat management, they usually use direct heat pipes or single-layer heat pipe structures, which have limited heat exchange area and the radial distribution uniformity of the temperature field still needs to be improved.

[0008] Therefore, developing a metal hydride hydrogen storage device with high heat exchange efficiency, uniform temperature field, and the ability to fundamentally avoid the risk of heat exchange fluid leakage is of great significance for promoting the practical application of solid-state hydrogen storage technology. Summary of the Invention

[0009] The purpose of this invention is to solve the above-mentioned technical problems by providing a metal hydride hydrogen storage device and thermal management method based on a finned multilayer spiral heat pipe.

[0010] The objective of this invention is achieved through the following technical solution:

[0011] A metal hydride hydrogen storage device based on finned multilayer spiral heat pipes includes: a heat exchanger, a hydrogen storage reactor tank, and at least two sets of spiral heat pipes with different diameters; the hydrogen storage reactor tank is filled with a hydrogen storage alloy, and the spiral heat pipes are arranged in a coaxial stacked manner to form a multilayer spiral heat pipe structure; one end of the multilayer spiral heat pipe structure is embedded inside the hydrogen storage alloy bed, and the other end extends to the outside of the tank and communicates with the heat exchanger; the outer wall of the tube section of the multilayer spiral heat pipe structure located inside the bed has spiral fins; the outer wall of the tube section of the multilayer spiral heat pipe located inside the heat exchanger is provided with annular fins; the hydrogen storage reactor tank is provided with valves for introducing or discharging hydrogen gas.

[0012] Furthermore, the heat exchanger is provided with a heat exchange fluid inlet and a heat exchange fluid outlet, and heat exchange fluid flows through its interior.

[0013] Furthermore, the intermediate pipe section between the hydrogen storage reactor tank and the heat exchanger in the multi-layer spiral heat pipe structure is an insulation section, and a heat insulation layer is provided on the insulation section.

[0014] Furthermore, during hydrogen absorption, the section of the multi-layer spiral heat pipe located inside the hydrogen storage alloy bed serves as the evaporation section, and the section located inside the heat exchanger serves as the condensation section; during hydrogen release, the section of the multi-layer spiral heat pipe located inside the hydrogen storage alloy bed serves as the condensation section, and the section located inside the heat exchanger serves as the evaporation section.

[0015] Furthermore, the thickness of the spiral fins is 0.5–1.0 mm.

[0016] Furthermore, the thickness of the annular fins is 0.5–1.0 mm, and the fin spacing is 5–15 mm.

[0017] Furthermore, the proportions of the evaporation section, condensation section, and adiabatic section of the multi-layer spiral heat pipe to the total length of the spiral heat pipe are 0.5-0.7, 0.2-0.4, and 0.05-0.15, respectively, and the sum of the lengths of the three sections is the total length of the spiral heat pipe.

[0018] Furthermore, the types of hydrogen storage alloys include lanthanum-nickel alloys, titanium alloys, and magnesium-based alloys.

[0019] Furthermore, the heat exchange fluid includes water, water vapor, and heat transfer oil.

[0020] A thermal management method for the above-mentioned metal hydride hydrogen storage device includes a hydrogen absorption process and a hydrogen release process;

[0021] The hydrogen absorption process includes:

[0022] Open the hydrogen valve and introduce hydrogen into the hydrogen storage reactor tank, so that the hydrogen reacts with the hydrogen storage alloy to generate metal hydrides and release the heat of reaction.

[0023] A multi-layer spiral heat pipe section embedded inside the hydrogen storage alloy bed is used as an evaporation section, so that the heat transfer medium in the evaporation section absorbs the heat of reaction and evaporates and vaporizes.

[0024] After vaporization, the heat transfer medium vapor flows along the multi-layer spiral heat pipe to the pipe section located inside the heat exchanger. This pipe section serves as the condensation section, where the vapor condenses and releases heat, transferring the heat to the heat exchange fluid inside the heat exchanger and being carried away by the heat exchange fluid outlet.

[0025] The condensed heat transfer medium liquid is returned to the evaporation section and circulated repeatedly until the hydrogen absorption reaction is completed;

[0026] The hydrogen release process includes:

[0027] Heat exchange fluid is introduced into the heat exchanger through the heat exchange fluid inlet, and the multi-layer spiral heat pipe section located inside the heat exchanger is used as the evaporation section, so that the heat transfer working medium in the evaporation section absorbs the heat of the heat exchange fluid and evaporates and vaporizes.

[0028] After vaporization, the heat transfer medium vapor flows along the multi-layer spiral heat pipe to the pipe section buried inside the hydrogen storage alloy bed. The pipe section serves as the condensation section, where the vapor condenses and releases heat, transferring the heat to the hydrogen storage alloy and providing heat for the hydrogen release reaction.

[0029] The condensed heat transfer medium liquid flows back to the evaporation section, and the cycle repeats. At the same time, the hydrogen valve is opened to release hydrogen gas until the hydrogen release reaction is complete.

[0030] The beneficial effects of this invention are as follows:

[0031] This invention uses a closed-loop heat pipe as the heat transfer medium, eliminating the risk of heat exchange fluid leakage at its source. This significantly improves the system's safety and long-term operational stability. Traditional hydrogen storage devices use a method where the heat exchange fluid is directly introduced into the reactor, posing a risk of heat exchange medium leakage. Once leaked, it can not only contaminate the hydrogen storage alloy, causing irreversible performance degradation, but may also lead to safety accidents. This invention uses a closed-loop heat pipe as the heat transfer medium, with the working fluid circulating within the closed cavity. This completely avoids direct contact between the heat exchange fluid and the hydrogen storage alloy, eliminating the leakage hazard at its source and significantly improving the system's safety and long-term operational stability.

[0032] This invention achieves a uniform temperature distribution in the reaction bed and improves hydrogen absorption / desorption kinetics through the synergistic effect of a nested arrangement of multi-layered spiral heat pipes and the phase change heat transfer characteristics of the heat pipes. On one hand, the invention uses at least two sets of coaxially nested spiral heat pipes of different diameters to form a three-dimensional "heat pipe network" within the limited radial space of the reactor, significantly expanding the heat exchange area and optimizing the radial temperature distribution. On the other hand, the heat pipes rely on the latent heat of phase change of the internal working fluid for heat transfer, and the evaporation and condensation sections operate at near-isothermal temperatures, quickly mitigating local hot or cold spots within the bed. This synergistic effect ensures a uniform temperature distribution in the reaction bed during hydrogen absorption / desorption, avoiding the reaction rate stagnation caused by uneven temperature in traditional structures, and effectively improving the hydrogen absorption / desorption kinetics and cycle stability of the hydrogen storage device.

[0033] This invention utilizes the reversibility of the heat pipe's operating direction to achieve intelligent switching between hydrogen absorption and release modes, thereby improving thermal response speed. During hydrogen absorption, the heat pipe section inside the bed acts as an evaporation section to remove the heat of reaction; during hydrogen release, this section automatically switches to a condensation section to introduce external heat into the bed. The entire switching process eliminates the need for a complex valve control system, achieving the dual thermal management requirements of "active heat dissipation during hydrogen absorption" and "active heat supply during hydrogen release," significantly improving the system's thermal response speed and overall energy efficiency.

[0034] This invention further enhances overall heat exchange efficiency by synergistically strengthening heat transfer through helical fins and annular fins. Helical fins are installed on the outer wall of the helical heat pipe inside the bed, effectively increasing the contact area between the heat pipe and the hydrogen storage alloy bed, overcoming the limitation of heat exchange caused by the low thermal conductivity of the alloy bed. Annular fins are installed on the outer wall of the heat pipe inside the heat exchanger, enhancing heat exchange between the heat pipe and the heat exchange fluid. These two fin structures respectively enhance heat exchange on the hydrogen storage alloy side and the heat exchange fluid side, working synergistically to further improve the overall heat exchange efficiency of the device. Attached Figure Description

[0035] Appendix Figure 1 This is a schematic diagram of the structure of a metal hydride hydrogen storage device based on a finned multilayer spiral heat pipe according to the present invention.

[0036] Appendix Figure 2 This is a schematic diagram of a multi-layer spiral heat pipe (without fins);

[0037] Appendix Figure 3 This is a schematic diagram of a single spiral heat pipe (with fins).

[0038] In the attached diagram: 1. Heat exchanger; 2. Heat exchange fluid inlet; 3. Circular fins; 4. Heat exchange fluid outlet; 5. Insulation layer; 6. Hydrogen storage reactor tank; 7. Outer spiral fins; 8. Inner spiral heat pipe; 9. Outer spiral heat pipe; 10. Inner spiral fins; 11. Hydrogen inlet and outlet valves; 12. Hydrogen storage alloy. Detailed Implementation

[0039] The present invention will now be further described with reference to the accompanying drawings.

[0040] like Figure 1 As shown, the present invention provides a metal hydride hydrogen storage device based on finned multilayer spiral heat pipes, including a heat exchanger 1, a hydrogen storage reactor tank 6, and at least two sets of spiral heat pipes with different diameters.

[0041] Inside the hydrogen storage reactor tank 6, two sets of spiral heat pipes with different diameters are installed: an outer spiral heat pipe 9 and an inner spiral heat pipe 8. The inner spiral heat pipe 8 is nested inside the outer spiral heat pipe 9, and the two are arranged coaxially to form a double-layer spiral heat pipe structure. The spiral axes of the outer spiral heat pipe 9 and the inner spiral heat pipe 8 coincide with the axis of the hydrogen storage reactor tank 6. It should be noted that the number of spiral heat pipe layers is not limited to two; it can also be three or more layers. The specific number of layers can be set according to the size of the hydrogen storage reactor and the heat exchange requirements.

[0042] The hydrogen storage reactor tank 6 is a cylindrical tank filled with hydrogen storage alloy 12. The type of hydrogen storage alloy 12 is selected according to the actual operating conditions, including but not limited to lanthanum-nickel alloys, titanium alloys, and magnesium-based alloys. The hydrogen storage device is preferably placed vertically, with the axis of the multi-layer spiral heat pipe parallel to the direction of gravity, so that the condensate can flow back to the evaporation section with the assistance of gravity.

[0043] One end of both the outer spiral heat pipe 9 and the inner spiral heat pipe 8 is embedded inside the hydrogen storage alloy 12 bed and arranged axially, with their length covering 80% of the bed height. The other ends of both heat pipes extend to the outside of the hydrogen storage reactor tank 6 and are connected to an external heat exchanger 1. The portion of the two heat pipes located outside the hydrogen storage reactor tank 6 and between it and the heat exchanger 1 is an insulation section. This insulation section is independently wrapped with 20mm thick glass wool insulation material 5 to reduce heat exchange with the environment.

[0044] Both the outer spiral heat pipe 9 and the inner spiral heat pipe 8 are sealed tubes filled with a heat transfer medium. This heat transfer medium is selected based on the operating temperature range of the hydrogen storage alloy 12: for example, when the hydrogen storage alloy is a room-temperature lanthanum-nickel alloy, acetone or ammonia can be used as the medium; when the hydrogen storage alloy is a high-temperature magnesium-based alloy, heat transfer oil or a sodium-potassium alloy can be used to ensure that the phase change temperature of the medium matches the reaction temperature.

[0045] To enhance heat transfer, the outer spiral heat pipe 9 and the inner spiral heat pipe 8 are located on the outer wall of the pipe section inside the hydrogen storage alloy 12 bed, and are respectively welded with outer spiral fins 7 and inner spiral fins 10, as shown in the specific structure. Figure 3 As shown. The thickness of the spiral fins is preferably 0.5–1.0 mm to maximize the heat exchange area while ensuring structural strength. Two heat pipes are located on the outer wall of the pipe section inside the heat exchanger 1, and both are welded with annular fins 3 to increase the heat exchange area with the heat exchange fluid. The thickness of the annular fins 3 is preferably 0.5–1.0 mm, and the fin spacing is preferably 5–15 mm.

[0046] The heat exchanger 1 is a shell-and-tube heat exchanger, with a heat exchange fluid inlet 2 and a heat exchange fluid outlet 4 on its shell, and a heat exchange fluid flowing inside. The heat exchange fluid can be selected from media such as water, steam, or heat transfer oil depending on the operating conditions. The hydrogen storage reactor tank 6 is equipped with hydrogen inlet and outlet valves 11 for controlling the entry and exit of hydrogen.

[0047] The evaporation section, condensation section, and insulation section of the multi-layer spiral heat pipe account for 0.5–0.7, 0.2–0.4, and 0.05–0.15% of the total length of the spiral heat pipe, respectively, and the sum of the lengths of the three sections equals the total length of the spiral heat pipe. Within this range, the effective heat exchange area inside the bed and the heat exchange efficiency of the external heat exchanger can be balanced, while ensuring the insulation effect of the insulation section.

[0048] The working principle and thermal management method of the device of the present invention are described in detail below:

[0049] Hydrogen absorption process:

[0050] During hydrogen absorption, the hydrogen inlet and outlet valves 11 are opened, allowing hydrogen to enter the hydrogen storage reactor tank 6 and react with the hydrogen storage alloy 12 to form metallic hydrides, releasing a large amount of heat. At this time, the outer spiral heat pipe 9 and the inner spiral heat pipe 8, embedded within the bed (i.e., the evaporation section), absorb the heat, causing the working fluid inside to evaporate and vaporize. The steam, carrying heat, flows through the adiabatic section to the section located within the heat exchanger 1 (i.e., the condensation section). In the condensation section, the heat is transferred to the heat exchange fluid within the heat exchanger 1 and carried away by the heat exchange fluid outlet 4, while the steam itself condenses into a liquid state. The condensate flows back to the evaporation section with the aid of gravity, completing one heat transfer cycle. Through this efficient and isothermal heat transfer method using heat pipes, the heat from the reaction bed is rapidly removed, ensuring the uniformity of the bed temperature. This cycle continues until the hydrogen absorption reaction is complete.

[0051] Hydrogen release process:

[0052] During the hydrogen release operation, an external heat source enters the heat exchanger 1 through the heat exchange fluid inlet 2, providing heat to the heat pipes. At this time, the heat pipes reversibly switch their operating mode. The pipe section within the heat exchanger 1 becomes the evaporation section, absorbing heat to vaporize the working fluid. The vapor flows to the pipe section inside the hydrogen storage alloy 12 bed (which then becomes the condensation section), where it condenses and releases heat, providing the necessary heat for the decomposition reaction of the hydrogen storage alloy 12. The condensed heat transfer working fluid liquid flows back to the evaporation section under gravity, repeating the cycle, while hydrogen valve 11 is opened to release hydrogen. This efficient heat input ensures the continuous progress of the hydrogen release reaction until it is complete.

[0053] Throughout the hydrogen absorption and release process, the insulation layer 5 effectively reduces the heat exchange between the insulation section and the environment, ensuring efficient heat transfer between the evaporation and condensation sections and avoiding heat loss along the way.

[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A metal hydride hydrogen storage device based on a finned multilayer spiral heat pipe, characterized in that, include: A heat exchanger (1), a hydrogen storage reactor tank (6), and at least two sets of spiral heat pipes with different diameters; the hydrogen storage reactor tank (6) is filled with a hydrogen storage alloy (12), and the spiral heat pipes are arranged in a coaxial stacked manner to form a multi-layer spiral heat pipe structure; one end of the multi-layer spiral heat pipe structure is buried inside the hydrogen storage alloy bed, and the other end extends to the outside of the tank and communicates with the heat exchanger (1); the outer wall of the tube section of the multi-layer spiral heat pipe structure located inside the bed has spiral fins; the outer wall of the tube section of the multi-layer spiral heat pipe located inside the heat exchanger (1) is provided with annular fins (3); the hydrogen storage reactor tank (6) is provided with a valve (11) for introducing or discharging hydrogen.

2. The metal hydride hydrogen storage device according to claim 1, characterized in that, The heat exchanger (1) is provided with a heat exchange fluid inlet (2) and a heat exchange fluid outlet (4), and heat exchange fluid flows through it.

3. The metal hydride hydrogen storage device according to claim 1, characterized in that, The intermediate section of the multi-layer spiral heat pipe structure between the hydrogen storage reactor tank (6) and the heat exchanger (1) is an insulation section, and a heat insulation layer (5) is provided on the insulation section.

4. The metal hydride hydrogen storage device according to claim 1, characterized in that, During hydrogen absorption, the section of the multi-layer spiral heat pipe located inside the hydrogen storage alloy bed serves as the evaporation section, and the section located inside the heat exchanger (1) serves as the condensation section; during hydrogen release, the section of the multi-layer spiral heat pipe located inside the hydrogen storage alloy bed serves as the condensation section, and the section located inside the heat exchanger (1) serves as the evaporation section.

5. The metal hydride hydrogen storage device according to claim 1, characterized in that, The thickness of the spiral fins is 0.5 to 1.0 mm.

6. The metal hydride hydrogen storage device according to claim 1, characterized in that, The thickness of the annular fins (3) is 0.5 to 1.0 mm, and the fin spacing is 5 to 15 mm.

7. The metal hydride hydrogen storage device according to claim 1, characterized in that, The evaporation section, condensation section, and adiabatic section of the multi-layer spiral heat pipe account for 0.5–0.7, 0.2–0.4, and 0.05–0.15 of the total length of the spiral heat pipe, respectively, and the sum of the lengths of the three sections is the total length of the spiral heat pipe.

8. The metal hydride hydrogen storage device according to claim 1, characterized in that, The types of hydrogen storage alloys (12) include lanthanum-nickel alloys, titanium alloys and magnesium-based alloys.

9. The metal hydride hydrogen storage device according to claim 2, characterized in that, The heat exchange fluid includes water, steam, and heat transfer oil.

10. A thermal management method for a metal hydride hydrogen storage device according to any one of claims 1-9, characterized in that, This includes the hydrogen absorption process and the hydrogen release process; The hydrogen absorption process includes: Open the hydrogen valve (11) and introduce hydrogen into the hydrogen storage reactor tank (6) so that the hydrogen reacts with the hydrogen storage alloy (12) to generate metal hydride and release the heat of reaction; A multi-layer spiral heat pipe section embedded inside the hydrogen storage alloy bed is used as an evaporation section, so that the heat transfer medium in the evaporation section absorbs the heat of reaction and evaporates and vaporizes. After vaporization, the heat transfer medium vapor flows along the multi-layer spiral heat pipe to the pipe section located inside the heat exchanger (1). The pipe section is used as the condensation section, so that the vapor condenses and releases heat in the condensation section, and transfers the heat to the heat exchange fluid in the heat exchanger (1) and is carried away by the heat exchange fluid outlet (4). The condensed heat transfer medium liquid is returned to the evaporation section and circulated repeatedly until the hydrogen absorption reaction is completed; The hydrogen release process includes: Heat exchange fluid is introduced into the heat exchanger (1) through the heat exchange fluid inlet (2), and the multi-layer spiral heat pipe section located inside the heat exchanger (1) is used as the evaporation section, so that the heat transfer medium in the evaporation section absorbs the heat of the heat exchange fluid and evaporates and vaporizes. After vaporization, the heat transfer medium vapor flows along the multi-layer spiral heat pipe to the pipe section buried inside the hydrogen storage alloy bed. The pipe section is used as the condensation section, so that the vapor condenses and releases heat in the condensation section, and transfers the heat to the hydrogen storage alloy (12) to provide heat for the hydrogen release reaction. The condensed heat transfer medium liquid flows back to the evaporation section and is circulated repeatedly. At the same time, the hydrogen valve (11) is opened to discharge hydrogen until the hydrogen release reaction is completed.

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