Hydrogen storage reactor based on synergistic heat management of phase change material and spiral heat exchange tube

Abstract

The invention discloses a hydrogen storage reactor based on synergistic heat management of a phase change material and a spiral heat exchange tube. The hydrogen storage reactor comprises an outer cylinder, a middle cylinder, an inner cylinder, a sealing cover and the spiral heat exchange tube. The outer cylinder, the middle cylinder and the inner cylinder divide the hydrogen storage reactor into three layers from inside to outside, and the inner layer and the outer layer are filled with phase change materials; the spiral heat exchange tube is arranged on the middle layer, and metal hydride is filled around the spiral heat exchange tube; in the hydrogen storage process, hydrogen flows into the middle layer of the reactor from an inlet in the center of the top end of the reactor and reacts with metal hydride; heat exchange fluid flows into the spiral heat exchange tube from a top inlet of the reactor, absorbs heat generated by reaction and flows out from a bottom outlet of the reactor; the phase change materials filled in the inner layer and the outer layer absorb heat generated by reaction and store the heat. The spiral heat exchange pipe is adopted for accelerating heat exchange, and the hydrogen storage and release rate is increased; the phase change material can store part of heat generated by the hydrogen storage reaction and release the heat during hydrogen release, the interlayer type arrangement can increase the heat exchange area, and the heat storage and release efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of metal hydride hydrogen storage reactor design, in particular to a hydrogen storage reactor based on phase change material and spiral heat exchange pipe cooperative thermal management. BACKGROUND

[0002] Under the background of global low-carbon energy transformation, seeking low-carbon emission and renewable alternative energy has become the research focus in the field of energy. Hydrogen energy is an important part of the future national energy system due to its wide range of sources, clean and efficient characteristics. Hydrogen has the characteristics of low density, flammability and explosiveness, which makes the hydrogen storage problem one of the main technical obstacles limiting the widespread use of hydrogen energy. Among the many hydrogen storage methods, solid-state hydrogen storage based on metal hydride has the advantages of high volume hydrogen storage density and safety, but the hydrogen storage and release process is accompanied by significant heat effect, which will seriously restrict the hydrogen storage and release performance if not accurately and effectively managed.

[0003] Phase change materials are good at high energy storage density, and coupling with metal hydride hydrogen storage system can form complementary advantages, optimize thermal management, and improve overall energy efficiency. However, due to the poor thermal conductivity of metal hydride and phase change material, the hydrogen storage and release rate is affected to some extent. Placing a heat exchange pipe in the metal hydride can improve the heat exchange rate and thus speed up the hydrogen storage and release rate, but this heat exchange method will bring the reaction heat to the outside of the system during hydrogen storage and dissipate it, and a large amount of heat needs to be input during hydrogen release, which cannot make full use of heat recycling and has high energy consumption. Under this background, the hydrogen storage reactor uses phase change material and heat exchange pipe heat exchange cooperative thermal management, which can improve the heat recovery rate while ensuring the heat exchange rate.

[0004] However, existing research generally considers phase change material and internal heat exchange pipe as two independent thermal management methods, and less considers the complementary advantages of the two when working together. There is little research on the coordinated control of hydrogen storage and release rate and heat energy recovery rate. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a hydrogen storage reactor based on phase change material and spiral heat exchange pipe cooperative thermal management to solve the defects involved in the background art.

[0006] The present application adopts the following technical solutions to solve the above technical problems:

[0007] The hydrogen storage reactor based on phase change material and spiral heat exchange pipe cooperative thermal management comprises an outer cylinder, a middle cylinder, an inner cylinder, a cover and a spiral heat exchange pipe.

[0008] The outer cylinder is a hollow cylinder or a hollow regular polygonal prism with an open upper end.

[0009] The middle cylinder is a hollow cylinder or a hollow regular polygonal prism with both ends open, and the middle cylinder is arranged in the outer cylinder, and the lower end of the middle cylinder is in close coaxial fixed connection with the bottom wall of the outer cylinder.

[0010] The inner cylinder is a hollow cylinder or a hollow regular polygonal prism with both ends open, and the inner cylinder is arranged in the middle cylinder, and the lower end of the inner cylinder is in close coaxial fixed connection with the bottom wall of the outer cylinder.

[0011] The cover is in close coaxial fixed connection with the upper end of the outer cylinder, the middle cylinder and the inner cylinder.

[0012] The spiral heat exchange pipe is sleeved outside the inner cylinder, and the upper end of the spiral heat exchange pipe extends out of the cover and is in close fixed connection with the cover, and the lower end of the spiral heat exchange pipe extends out of the bottom wall of the outer cylinder and is in close fixed connection with the bottom wall of the outer cylinder, and is used for connecting an external heat exchange fluid.

[0013] The outer cylinder, the middle cylinder and the cover form a filling A area, the middle cylinder, the inner cylinder, the cover and the bottom wall of the outer cylinder form a filling B area, and the inner cylinder, the cover and the bottom wall of the outer cylinder form a filling C area; the filling A area is filled with a phase change material, the filling B area is filled with a hydrogen storage material, and the filling C area is filled with a phase change material.

[0014] The cover is further provided with an air pipe in communication with the filling B area, which serves as a hydrogen outlet / inlet.

[0015] As a further optimization scheme of the hydrogen storage reactor based on the cooperation of the phase change material and the spiral heat exchange pipe for heat management, the hydrogen storage material filled in the filling B area adopts any one of the following materials: LaNi5, Mg, Mg2Ni.

[0016] As a further optimization scheme of the hydrogen storage reactor based on the cooperation of the phase change material and the spiral heat exchange pipe for heat management, the phase change material filled in the filling A area and the filling C area adopts any one of the following materials: paraffin, fatty acid, sodium nitrate.

[0017] As a further optimization scheme of the hydrogen storage reactor based on the cooperation of the phase change material and the spiral heat exchange pipe for heat management, the heat exchange fluid connected in the spiral heat exchange pipe adopts any one of the following fluids: water, air, molten salt.

[0018] Compared with the prior art, the application has the following technical effects:

[0019] 1. The application adopts a sandwich type distribution structure filled with hydrogen storage materials between two layers of phase change materials, which increases the heat exchange area compared with a jacket type distribution structure, can improve the heat exchange rate between the phase change materials and the hydrogen storage materials, optimizes the heat distribution between the phase change materials, and improves the energy recovery rate.

[0020] 2. The present application is filled with spiral heat exchange tube in B area, compared with straight tube heat exchange tube, the structure increases the heat exchange area, improves the heat exchange rate, at the same time, the spiral structure is matched with the filling B area under the distribution of hydrogen storage-heat storage sandwich, which can further optimize the heat distribution.

[0021] 3. For the imbalance between hydrogen storage and release rate and heat recovery rate, the present application adopts the method of time period control of fluid into the spiral heat exchange tube, at the beginning of hydrogen storage / hydrogen release reaction, the heat exchange fluid is passed in, when the hydrogen storage / hydrogen release reaction reaches 90%, the heat exchange fluid is stopped, the reaction heat of filling B area flows into the phase change material in the following time, which improves the heat recovery rate. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a structural schematic diagram of the present application;

[0023] Figure 2 is a sectional view schematic diagram of the present application;

[0024] Fig. 3(a), Fig. 3(b) are hydrogen storage fraction-time curve comparison diagram and heat recovery rate-time curve comparison diagram of the present application and comparative example respectively.

[0025] In the figure, 1 is an outer cylinder, 2 is a middle cylinder, 3 is an inner cylinder, 4 is a cover, 5 is a spiral heat exchange tube, 6 is the upper end of the spiral heat exchange tube, 7 is the lower end of the spiral heat exchange tube, 8 is a hydrogen inlet / outlet, 9 is a filling A area, 10 is a filling B area, 11 is a filling C area. DETAILED DESCRIPTION

[0026] The technical solutions of the present application will be further described in detail below in combination with the drawings:

[0027] The present application can be implemented in many different forms, and should not be considered limited to the embodiments described herein. On the contrary, these embodiments are provided to make the present disclosure thorough and complete, and to fully convey the scope of the present application to those skilled in the art. In the drawings, the components are enlarged for clarity.

[0028] It should be understood that although the terms first, second, third, etc. can be used herein to describe various elements, components and / or parts, these elements, components and / or parts are not limited by these terms. These terms are only used to distinguish one element, component and / or part from another. Therefore, the first element, component and / or part discussed below can become the second element, component or part without departing from the teaching of the present application.

[0029] In the description of the present application, it should be understood that the terms "horizontal", "vertical", "left", "right", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application, and cannot be understood as a limitation on the present application; the terms "mounting", "connecting", "fixing", etc. should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral connection, it can be direct connection, or indirect connection through intermediate medium, or internal communication of two elements; for those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0030] Referring to Figure 1 , Figure 2 The present application provides a hydrogen storage reactor based on phase change material and spiral heat exchange pipe cooperative thermal management, comprising an outer cylinder, a middle cylinder, an inner cylinder, a cover and a spiral heat exchange pipe.

[0031] The outer cylinder is a hollow cylinder or a hollow regular polygonal prism with an open upper end;

[0032] The middle cylinder is a hollow cylinder or a hollow regular polygonal prism with open ends, the middle cylinder is arranged in the outer cylinder, and the lower end of the middle cylinder is fixedly and coaxially connected to the bottom wall of the outer cylinder in a sealed manner;

[0033] The inner cylinder is a hollow cylinder or a hollow regular polygonal prism with open ends, the inner cylinder is arranged in the middle cylinder, and the lower end of the inner cylinder is fixedly and coaxially connected to the bottom wall of the outer cylinder in a sealed manner;

[0034] The cover is fixedly and coaxially connected to the upper ends of the outer cylinder, the middle cylinder and the inner cylinder in a sealed manner;

[0035] The spiral heat exchange pipe is sleeved outside the inner cylinder, the upper end of the spiral heat exchange pipe extends out of the cover and is fixedly connected to the cover in a sealed manner, and the lower end of the spiral heat exchange pipe extends out of the bottom wall of the outer cylinder and is fixedly connected to the bottom wall of the outer cylinder in a sealed manner, and is used for connecting external heat exchange fluid;

[0036] The outer cylinder, the middle cylinder and the cover form a filling A area, the middle cylinder, the inner cylinder, the cover, the bottom wall of the outer cylinder form a filling B area, and the inner cylinder, the cover and the bottom wall of the outer cylinder form a filling C area; the filling A area is filled with phase change material, the filling B area is filled with hydrogen storage material, and the filling C area is filled with phase change material;

[0037] The cover is further provided with an air pipe connected to the filling B area, which serves as a hydrogen outlet / inlet.

[0038] In the hydrogen storage process, hydrogen gas enters the reactor from the hydrogen gas inlet, flows into the filled B zone along the channel, and reacts with the hydrogen storage material to form metal hydride; at the same time, the heat exchange fluid flows into the reactor from the heat exchange fluid inlet, flows through the filled B zone along the pipeline of the spiral heat exchange tube, absorbs part of the heat released by the hydrogen storage reaction, and then flows out from the heat exchange fluid outlet at the bottom end of the outer cylinder; the phase change materials in the filled A zone and the filled C zone absorb the heat released by the hydrogen storage reaction from both sides of the hydrogen storage material, and store these heat in the form of latent heat and sensible heat for use during the hydrogen release process.

[0039] In the hydrogen release process, the heat exchange fluid flows into the reactor from the heat exchange fluid inlet, flows through the filled B zone along the pipeline of the spiral heat exchange tube, releases heat to the filled B zone to drive the hydrogen release reaction, and then flows out from the heat exchange fluid outlet at the bottom end of the outer cylinder; the phase change materials in the filled A zone and the filled C zone release the stored heat and transfer it to the filled B zone to accelerate the hydrogen release process; under certain pressure conditions, the metal hydride in the filled B zone undergoes a hydrogen release reaction and absorbs the heat provided by the phase change materials and the spiral heat exchange tube, and after the hydrogen is released, it flows along the channel to the top end of the outer cylinder and then flows out of the reactor from the hydrogen gas outlet.

[0040] In the hydrogen storage process, the reactor starts to store hydrogen at the same time as the heat exchange fluid is introduced into the spiral heat exchange tube from the heat exchange fluid inlet, and when the hydrogen storage amount reaches about 90%, the introduction of the heat exchange fluid is stopped, and the remaining heat is absorbed by the phase change materials. In the hydrogen release process, the reactor starts to release hydrogen at the same time as the heat exchange fluid is introduced into the spiral heat exchange tube from the heat exchange fluid inlet, and when the hydrogen release amount reaches about 90%, the introduction of the heat exchange fluid is stopped, and the remaining heat is absorbed by the phase change materials.

[0041] The hydrogen storage material filled in the filled B zone is mainly metal hydride hydrogen storage material, and the hydrogen storage materials that can be selected include but are not limited to LaNi5, Mg, Mg2Ni. The reaction temperature and reaction pressure of different hydrogen storage materials are different, and the reaction temperature and reaction pressure of the hydrogen storage and release process of the same material are also different.

[0042] According to the reaction temperature of the hydrogen storage material, the phase change materials can be selected and matched according to the melting point of the phase change materials, and different phase change materials can be selected to fill the filled A zone and the filled C zone, including but not limited to paraffin, fatty acid, and sodium nitrate.

[0043] According to the reaction temperature of the hydrogen storage material, the heat exchange fluid in the spiral heat exchange tube can be selected and matched according to the melting point and boiling point of the heat exchange fluid, including but not limited to water, air, and molten salt.

[0044] Taking Mg2Ni as the hydrogen storage material as an example, the hydrogen storage reaction temperature is 573K, the reaction pressure is 1.5MPa, and in order to match the hydrogen storage reaction temperature, NaNO3 is selected as the phase change material in the filled A zone and the filled C zone, and 60% NaNO3-40% KNO3 binary molten salt is selected as the heat exchange fluid.

[0045] Hydrogen enters the reactor from the hydrogen inlet, enters the filled B zone along the channel, and reacts with Mg2Ni to release hydrogen; at the same time, the heat exchange fluid flows into the reactor from the heat exchange fluid inlet, flows through the filled B zone along the pipeline of the spiral heat exchange tube, absorbs part of the heat released by the hydrogen storage reaction, and then flows out from the heat exchange fluid outlet at the bottom end of the outer cylinder; the phase change material in the filled A zone and the filled C zone absorbs the heat released by the hydrogen storage reaction from both sides of the hydrogen storage material, and stores these heat in the form of latent heat and sensible heat for use when hydrogen is released. Stop flowing in the heat exchange fluid when the hydrogen storage capacity reaches about 90%, and the remaining heat is absorbed by the phase change material.

[0046] To intuitively explain the advantages of the sandwich type phase change material and the spiral heat exchange tube in the metal hydride hydrogen storage reactor, a multi-physical field model was established, and numerical calculation was performed, and the results are shown in FIGS. 3(a) and 3(b). Comparative Example 1 is a traditional metal hydride hydrogen storage reactor coupled with phase change material, and Comparative Example 2 is a metal hydride hydrogen storage reactor with sandwich type phase change material and spiral heat exchange tube for collaborative thermal management. The types and amounts of metal hydride and phase change material in Comparative Example 1 are the same as in the embodiment, and the specification parameters of the spiral heat exchange tube, as well as the types and flow rates of the heat exchange fluid in Comparative Example 2 are the same as in the embodiment.

[0047] When the hydrogen storage fraction reaches 90%, it can be considered that the hydrogen storage reaction is basically completed. As can be seen from FIG. 3(a), the hydrogen storage reaction completion time of Comparative Example 2 and the example is 34 min and 14 min respectively, and the hydrogen storage reaction completion time of Comparative Example 1 is more than 100 min, and the hydrogen storage reaction rate is far lower than the other two. This is because Comparative Example 1 does not use an internal heat exchange tube, and only relies on the phase change material to absorb the heat released by the metal hydride. Excessive heat accumulation further hinders the progress of the hydrogen storage reaction; the hydrogen storage reaction rate of the example is improved by 58.8% compared with Comparative Example 2. Because compared with the jacket type hydrogen storage-heat storage distribution structure, the sandwich type structure increases the heat exchange area between the phase change material and the metal hydride, accelerates the heat exchange rate between the two, and thus accelerates the progress of the hydrogen storage reaction. The ratio of the heat stored by the phase change material to the total heat released by the metal hydride during hydrogen storage is used as the heat energy recovery rate. As can be seen from FIG. 3(b), at 100 min, the heat energy recovery rates of Comparative Example 1, Comparative Example 2 and the example are 82.8%, 34.7% and 57.7% respectively. In Comparative Example 2 and the example, an internal spiral heat exchange tube is used, which will cause a part of the heat to be taken away by the heat exchange fluid and cannot be recycled, so the heat energy recovery rates of the two are lower than that of Comparative Example 1. At about 30 min, the heat energy recovery rate of Comparative Example 2 decreases, and at 34 min, the heat energy recovery rate begins to rise because the heat exchange fluid is stopped. Because there is a problem of obvious heat distribution unevenness in this hydrogen storage-heat storage distribution structure, the spiral heat exchange tube begins to absorb the heat stored in the phase change material after absorbing the heat of the outer layer of the metal hydride. The sandwich type distribution structure used in the example can effectively improve this problem of uneven heat distribution, and because of the faster heat exchange rate of the structure, the heat energy recovery rate is significantly higher than that of Comparative Example 2.

[0048] The present application solves the problem of low heat recycling rate in the reactor, and at the same time uses the spiral heat exchange tube to improve the overall hydrogen storage and release rate. In one or more embodiments, according to the actual use requirement, the hydrogen storage rate and the heat energy recovery rate can be regulated by controlling the time length of the heat exchange fluid.

[0049] Those skilled in the art can understand that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It should also be understood that terms such as those defined in general dictionaries should be understood as having meanings consistent with those in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless otherwise defined.

[0050] The above detailed description of the specific embodiments of the present application has been given to understand the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A hydrogen storage reactor based on phase change material and helical heat exchanger pipe collaborative thermal management, characterized in that, It comprises an outer cylinder, a middle cylinder, an inner cylinder, a cover and a spiral heat exchange pipe. The outer cylinder is a hollow cylinder or a hollow regular polygonal prism with an open upper end. The middle cylinder is a hollow cylinder or a hollow regular polygonal prism with open ends, which is arranged in the outer cylinder, and the lower end of the middle cylinder is fixedly connected with the bottom wall of the outer cylinder. The inner cylinder is a hollow cylinder or a hollow regular polygonal prism with open ends, which is arranged in the middle cylinder, and the lower end of the inner cylinder is fixedly connected with the bottom wall of the outer cylinder. The cover is fixedly connected with the upper ends of the outer cylinder, the middle cylinder and the inner cylinder. The spiral heat exchange pipe is sleeved on the outer cylinder, and the upper end of the pipe extends out of the cover and is fixedly connected with the cover, and the lower end of the pipe extends out of the bottom wall of the outer cylinder and is fixedly connected with the bottom wall of the outer cylinder, so as to be connected with external heat exchange fluid. The outer cylinder, the middle cylinder and the cover form a filling A area, the middle cylinder, the inner cylinder, the cover and the bottom wall of the outer cylinder form a filling B area, and the inner cylinder, the cover and the bottom wall of the outer cylinder form a filling C area. The cover is further provided with an air pipe connected with the filling B area, which serves as a hydrogen outlet / inlet.

2. The hydrogen storage reactor based on phase change material and helical heat exchanger pipe collaborative thermal management according to claim 1, characterized in that, The hydrogen storage material filled in the filling B area is any one of LaNi5, Mg and Mg2Ni.

3. The phase change material and helical heat exchanger tube based cooperative thermal management based hydrogen storage reactor as claimed in claim 1, wherein, The phase change material filled in the filling A area and the filling C area is any one of paraffin, fatty acid and sodium nitrate.

4. The phase change material and helical heat exchanger tube based cooperative thermal management based hydrogen storage reactor as claimed in claim 1, wherein, The heat exchange fluid connected with the spiral heat exchange pipe is any one of water, air and molten salt.

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