Solid waste-based two-stage porous structure and directional mass transfer composite heat storage material and preparation method

Abstract

The disclosure provides a solid waste-based two-stage pore structure and directional mass transfer composite heat storage material and a preparation method, and belongs to the technical field of industrial solid waste resource utilization and energy saving. The preparation method comprises the following steps: mixing steel slag, fly ash and a binder to form a mixed slurry, and forming a first green body with a preset columnar channel through 3D printing; sintering and pore control treatment are performed on the first green body to obtain a second green body with a micro-nano porous structure; an interlaced distribution of macro-micro size prismatic channel is constructed in the second green body to form a third green body; sodium salt and magnesium salt are injected into the third green body by a vacuum impregnation method, and high-concentration brine impregnation is performed in the micro-nano porous structure to form a solid salt, thereby obtaining a fourth green body; through calcination treatment, the solid salt in the micro-nano porous structure is decomposed and migrated into the prismatic channel, thereby obtaining a solid waste-based two-stage pore structure composite heat storage material, and "two-stage pore + directional mass transfer" is first proposed, and the heat storage performance is improved.

Description

Technical Field

[0001] This disclosure belongs to the field of industrial solid waste resource utilization and energy conservation technology, specifically relating to a solid waste-based dual-level porous structure and directional mass transfer composite thermal storage material and its preparation method. Background Technology

[0002] In the field of solid waste resource utilization, existing technologies have made some progress.

[0003] For example, one of the existing technologies, Chinese patent application CN118005360A, proposes a solid waste-slag synergy and full particle size optimization fluidized solidified soil and its preparation method, which realizes the resource reuse of various solid wastes, while having good physical properties and is suitable for various engineering backfilling and reinforcement fields.

[0004] For example, one of the existing technologies, Chinese patent application CN115448659A, provides a method for preparing recycled concrete from solid waste stainless steel slag based on the coupling effect of early carbonization and early wet-dry cycle. This method not only makes efficient use of industrial waste materials, but also produces concrete with high compressive strength, high density, corrosion resistance, freeze resistance, and early strength. It can also significantly save costs and make a positive contribution to environmental protection.

[0005] However, most of the above technologies focus on the resource utilization of solid waste to generate materials such as concrete, and there are still shortcomings in the field of thermal storage materials, especially in terms of solving kinetic hysteresis, improving thermal storage density and cycle stability.

[0006] Furthermore, traditional solid waste-based thermal storage materials often suffer from poor thermal storage performance due to low mass transfer efficiency and limited salt loading. Their thermal storage density decreases significantly after repeated use, limiting their application in high-efficiency energy storage and conversion systems. Summary of the Invention

[0007] This disclosure aims to at least solve one of the technical problems existing in the prior art, and to provide a solid waste-based dual-level porous structure and directional mass transfer composite thermal storage material and its preparation method.

[0008] One aspect of this disclosure provides a method for preparing a solid waste-based dual-level porous structure and directional mass transfer composite thermal storage material, the preparation method comprising:

[0009] Steel slag, fly ash and binder are mixed to form a mixed slurry, and the mixed slurry is 3D printed to form a first blank with a preset columnar channel;

[0010] The first blank is subjected to sintering and porosity control treatment in sequence to obtain a second blank with a micro-nano porous structure.

[0011] Through multi-scale and multi-directional channel design, staggered macro- and micro-sized frustum-shaped channels are constructed in the second blank to form a third blank with micro-nano porous structure and frustum-shaped channels;

[0012] A mixed solution of sodium and magnesium salts is injected into the third preform using a vacuum impregnation method. The preform is then impregnated with a high-concentration brine in its micro-nano porous structure, causing some of the water in the micro-nano porous structure to be replaced by the brine. After drying, solid salt is formed in the micro-nano porous structure, resulting in a fourth preform.

[0013] By calcining, the solid salts in the micro-nano porous structure of the fourth preform are decomposed and migrated into the frustum-shaped channels, thus obtaining a solid waste-based dual-level porous composite thermal storage material.

[0014] Optionally, the weight ratio of the steel slag, fly ash and binder is (5~7):1:1.

[0015] Optionally, the adhesive is PVA.

[0016] Optionally, sintering the first blank includes:

[0017] Sintering was carried out in an air atmosphere: the temperature was raised from room temperature to 500 °C within 3 hours and held for 5 hours; then the temperature was raised from 500 °C to 800 °C at a rate of 10 °C / min and held for 6 hours.

[0018] Optionally, the first blank is subjected to porosity control treatment, including:

[0019] The first sintered blank was placed in a nitrogen atmosphere in a tube furnace, heated to 400 °C, held for 8 hours, and then naturally cooled to 25 °C. The above pore control sintering process was repeated twice.

[0020] Optionally, the staggered macro- and micro-sized frustum-shaped channels include at least two sets of frustum-shaped channels distributed in different directions.

[0021] Optionally, the sodium salt is sodium chloride, and the magnesium salt is magnesium sulfate; the mixed solution of sodium chloride and magnesium sulfate is a saturated aqueous solution or a near-saturated aqueous solution, and the total salt mass fraction is not less than 25%.

[0022] Optionally, during the process of injecting a mixed solution of sodium and magnesium salts into a porous third preform using a vacuum impregnation method, the vacuum degree is 0.05 MPa.

[0023] Optionally, the calcination treatment is carried out at a temperature of 500-700°C for a time of 8 hours or more.

[0024] In another aspect of this disclosure, a solid waste-based dual-porous structure and directional mass transfer composite thermal storage material is proposed. This solid waste-based dual-porous structure and directional mass transfer composite thermal storage material is prepared by the preparation method described above. For details, please refer to the description above.

[0025] This disclosure proposes a solid waste-based composite thermal storage material with a dual-level porous structure and directional mass transfer, as well as its preparation method. The preparation method includes: mixing steel slag, fly ash, and a binder to form a slurry; using 3D printing to form a first preform with pre-defined columnar channels; sequentially subjecting the first preform to sintering and porosity control treatments to obtain a second preform with a micro / nano porous structure; constructing staggered macro- and micro-sized frustum-shaped channels in the second preform through multi-scale, multi-directional channel design to form a third preform with a micro / nano porous structure and frustum-shaped channels; injecting a mixed solution of sodium and magnesium salts into the third preform using a vacuum impregnation method; impregnating the micro / nano porous structure of the third preform with a high-concentration brine solution to replace some of the water in the micro / nano porous structure with brine; then drying to form solid salt in the micro / nano porous structure to obtain a fourth preform; and finally, calcining to decompose and migrate the solid salt in the micro / nano porous structure of the fourth preform into the frustum-shaped channels, thus obtaining the solid waste-based composite thermal storage material with a dual-level porous structure. The composite thermal storage material disclosed herein has macroscopic frustum-shaped channels and micro / nano porous structures. The frustum-shaped channels are used for rapid mass transfer, and the micro / nano porous structures are used for efficient salt storage, giving the material the advantages of high thermal storage density and high mass transfer efficiency. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of a method for preparing a solid waste-based dual-level porous structure and directional mass transfer composite thermal storage material according to a specific embodiment of this disclosure.

[0027] Figure 2 This is a schematic diagram of a solid waste-based dual-stage porous structure and directional mass transfer composite thermal storage material according to a specific embodiment of this disclosure.

[0028] Figure 3 This is a schematic diagram of primary and secondary pores in a specific embodiment of this disclosure;

[0029] Figure 4 The micropore structure and salt migration process of the specific embodiments of this disclosure;

[0030] Figure 5 The curves show the comparison of the thermal conductivity of the solid waste-based composite thermal storage material (SHS) prepared in Example 1 of this disclosure with the materials in Comparative Examples 1 and 2. Detailed Implementation

[0031] To enable those skilled in the art to better understand the technical solutions of this disclosure, the disclosure will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain this disclosure and represent a part of the embodiments of this disclosure, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the protection scope of this disclosure.

[0032] As shown in Figure 1, one aspect of this disclosure provides a method for preparing a solid waste-based dual-level porous structure and directional mass transfer composite thermal storage material, specifically including the following steps S110~S150:

[0033] S110. Steel slag, fly ash, and binder are mixed to form a slurry. The slurry is then 3D printed to form a first preform with pre-defined columnar channels. Figure 1 Process 1.

[0034] In step S110, the weight ratio of steel slag, fly ash and binder is (5~7):1:1.

[0035] In step S110, the adhesive is PVA.

[0036] like Figure 1 As shown, the first blank refers to a green blank formed by 3D printing, which has a pre-set columnar channel. Figure 1 In the process 1 diagram, the broken line represents the movement path of the 3D printing head or the stacking direction of the material. That is, the macroscopic columnar channel formed directly by 3D printing is the primary pore, and its main function is to serve as the main channel for rapid mass transfer.

[0037] S120. The first billet undergoes specific sintering treatment and high-temperature treatment to regulate porosity, triggering a carbonization reaction between calcium oxide and carbon dioxide in the steel slag. Subsequent heat treatment in a specific atmosphere optimizes the porosity, forming a rich micro / nano porous structure on the outer surface of the columnar channels and within the first billet matrix, resulting in a second billet with a micro / nano porous structure. Figure 1 Process 2.

[0038] It should be noted that step S120 includes two stages: The first stage is a high-temperature sintering treatment, specifically including raising the temperature from room temperature to 500 °C within 3 hours in an air atmosphere, and then holding the temperature for 5 hours; then raising the temperature from 500 °C to 800 °C at a rate of 10 °C / min, and holding it for 6 hours. The second stage is a high-temperature porosity control treatment, specifically including placing the sintered green body in a nitrogen atmosphere in a tube furnace, raising the temperature to 400 °C, holding it for 8 hours, and then naturally cooling it to 25 °C; this process is repeated twice to ultimately form a micro-nano porous structure for efficiently loading thermal storage salts.

[0039] In step S120, micropores are constructed on the surface of the macroscopic columnar channel and in the first blank matrix through carbonization reaction and specific heat treatment, providing a "salt storage carrier" for subsequent salt loading and forming a two-level pore prototype of "macroscopic channel-micropore".

[0040] like Figure 1 As shown, secondary pores are formed in the matrix material constituting the first blank, that is, equivalent to forming on the wall of the macroscopic columnar channel. These secondary pores are micro-nano pore structures. This structure serves as the initial "salt storage carrier". In the subsequent roasting steps, the salt will migrate from these micro-pores to the macroscopic channel. In other words, the second blank refers to the blank with a micro-nano porous structure obtained after sintering and pore control of the first blank.

[0041] It should be noted that, Figure 1 The broken line in the graph of process 2 represents the temperature change curve during the heat treatment process. This shows that the present embodiment adopts a complex heat treatment with a specific heating and holding procedure, and further shows that the pore control is a controlled heat treatment process.

[0042] S130. Through multi-scale, multi-directional channel design, staggered macro- and micro-sized frustum-shaped channels are constructed in the second blank to form a third blank with a micro-nano porous structure and frustum-shaped channels. That is, multi-directional frustum-shaped channels are further formed on the basis of the second blank, such as... Figure 1 Process 3.

[0043] In step S130, a pre-defined through columnar channel is directly machined into the second blank using computer-aided design (CAD) modeling and 3D printing technology. These staggered frustum-shaped channels include at least two independent directions. In other words, the staggered macro-micro dimensional frustum-shaped channels include at least two sets of frustum-shaped channels distributed in different directions.

[0044] In step S130, the third blank refers to the porous second blank from S120 that has undergone secondary processing using a 3D printer, based on the second blank. This further processes the original columnar channels to create frustum-shaped channels, ultimately forming a staggered distribution of macroscopic and microscopic frustum-shaped channels. This "staggered frustum-shaped design" optimizes the mass transfer path (increasing channel surface area and path diversity), improving macroscopic mass transfer efficiency. The multi-scale channels (macroscopic frustum + microscopic porosity) lay the foundation for subsequent directional salt migration.

[0045] S140. A mixed solution of sodium and magnesium salts is injected into a porous third preform using a vacuum impregnation method. The third preform is then impregnated with a high-concentration brine solution within its micro / nano porous structure, causing partial water replacement by the brine. After drying, a heat-storing salt (NaCl / MgSO4) is formed, yielding a fourth preform. Figure 1 Process 4.

[0046] In step S140, the sodium salt is sodium chloride, the magnesium salt is magnesium sulfate, and the mixed solution of sodium chloride and magnesium sulfate is a high-concentration brine, which is prepared by the following method: at 20°C to 30°C, an excess of the mixed salt of sodium chloride and magnesium sulfate is added to deionized water, and the mixture is stirred continuously until undissolved salt crystals are present in the solution to ensure that the solution reaches saturation. The total salt mass fraction of the saturated solution is not less than 25%.

[0047] In step S140, the vacuum level is 0.05 MPa.

[0048] In step S140, the salt solution is permeated into the micro-nano pores (secondary pores) formed in step S120 by using vacuum negative pressure and capillary action, displacing the water in the pores and removing excess water, so that the salt is retained in the micro-nano pores in the form of a saturated solution or crystals. The efficient loading of salt in the micro-pores is achieved by vacuum impregnation. In other words, the fourth blank refers to the further loading of solid salt in the micro-nano pores on the basis of the third blank.

[0049] It should be noted that, Figure 1 In the diagram corresponding to process 4, the triangular arrow points to the container or injection head holding the mixed solution of sodium and magnesium salts. The arrow points from the triangle to the billet, clearly indicating the flow direction of the salt solution being drawn into the porous billet under the drive of the difference between the external atmospheric pressure and the vacuum negative pressure (0.05MPa) inside the billet.

[0050] S150. Through calcination, the solid salts in the micro-nano porous structure of the fourth preform are decomposed and migrated into the frustum-shaped channels, resulting in a solid waste-based dual-level porous composite thermal storage material, such as... Figure 1 In process 5, heat storage salt is distributed inside and on the inner surface of the macroscopic columnar channel 1 through calcination. The arrows in the figure corresponding to process 5 represent the directional migration path and direction of the salt. The starting point of the arrow represents the micro-nano pore structure, and the ending point points to the inner wall of the macroscopic frustum-shaped channel. Black rectangular blocks representing "heat storage salt crystals" are formed on the inner wall of the channel.

[0051] In step S150, the calcination temperature is 500-700°C, and the calcination time is more than 8 hours. Through calcination, the solid salt components loaded in the micro-nano porous structure of the fourth preform soften, melt, or partially decompose, thereby increasing their fluidity. Driven by concentration gradient, capillary action, and surface energy difference, these melted or softened salts migrate out of the micropores and migrate directionally along the pore network, converging into the macroscopic frustum-shaped channels with a larger surface area. They recrystallize or deposit within the channels, realizing the directional migration of salt from the "microscopic salt storage carrier" to the "macroscopic mass transfer channel," forming a synergistic system of "microscopic pore salt storage - macroscopic channel heat transfer," thereby improving heat storage density and heat exchange efficiency.

[0052] It should be noted that the macroscopic frustum-shaped channel with a larger surface area here refers to its larger surface area compared to micro / nano porous structures.

[0053] This embodiment proposes a directional mass transfer preparation method for a solid waste-based bilevel porous composite thermal storage material. The aim is to significantly improve the mass transfer efficiency, thermal storage density, and cycle stability of the material by constructing directional columnar channels and interconnected nanopores, and by using solid waste matrix modification and salt loading optimization techniques, while achieving efficient utilization of solid waste resources.

[0054] In another aspect of this disclosure, a solid waste-based dual-level porous structure and directional mass transfer composite thermal storage material is proposed. This solid waste-based dual-level porous structure and directional mass transfer composite thermal storage material is prepared by the preparation method described above. For the specific preparation process, please refer to the description above, which will not be repeated here.

[0055] The solid waste-based bi-level porous composite thermal storage material prepared by the method described above in this embodiment has the following structure: Figure 2 As shown, label 6 represents macroscopic frustum-shaped channels, which belong to primary pores; label 7 represents micro-nano pore structures, which belong to secondary pores; label 8 represents thermal storage salt crystals (NaCl / MgSO4); and label 9 represents solid waste matrix (steel slag / fly ash).

[0056] Further, refer to Figure 3 As shown, label 12 represents the solid waste matrix (steel slag / fly ash), which serves as a structural support material; label 11 represents the micro-nano pore structure, which belongs to the secondary pores and serves as a salt storage carrier; and label 10 represents the macroscopic frustum-shaped channel, which belongs to the primary pores and serves as a rapid mass transfer channel.

[0057] Furthermore, such as Figure 4As shown, the process of salt migration based on microporous structure is presented. In this paper, 13 represents salt in micro-nano pores before migration, 14 represents vacant micro-nano pores, 15 represents salt crystals during migration, 16 represents the salt migration direction, 17 represents salt crystals in macroscopic channels after migration, 18 represents vacant micro-nano pores after migration, and 19 represents the solid waste matrix.

[0058] The composite thermal storage material disclosed herein has high thermal storage performance, low operating temperature, low cost, wide availability of raw materials, environmental friendliness, long service life, and can be applied on a large scale.

[0059] The preparation method of solid waste-based dual-level porous structure and directional mass transfer composite thermal storage material will be further explained below with reference to specific embodiments:

[0060] Example 1

[0061] (1) Solid waste matrix molding: Steel slag, fly ash and binder are mixed in a weight ratio of 6:1:1 to obtain a mixed slurry. The mixed slurry is used to obtain a first blank with a preset columnar channel by 3D printing technology and dried at 70 °C for 6 h.

[0062] (2) High-temperature sintering treatment: The first green body was placed in a muffle furnace for sintering. The heating program was as follows: the temperature was raised from room temperature to 500 °C within 3 hours, and then held for 5 hours; then the temperature was raised from 500 °C to 800 °C at a rate of 10 °C / min, and held for 6 hours. The green body was taken out after natural cooling to room temperature; Pore structure control treatment: The green body after high-temperature calcination was placed in a tube furnace, and then the temperature was slowly raised to 400 °C while continuously introducing nitrogen gas. It was calcined at 400 °C for 8 hours, and then naturally cooled to 25 °C; the above process was repeated twice to obtain a porous second green body with a preliminary bilevel pore structure.

[0063] (3) Construction of mass transfer channels: Model the porous second blank using computer-aided design software (CAD) and use a 3D printer to perform secondary processing on the second blank, and establish at least two sets of frustum-shaped through channels distributed in different directions in the second blank to obtain the third blank;

[0064] (4) Vacuum impregnation: Prepare a saturated mixed solution of sodium chloride and magnesium sulfate: At 25°C, add excess mixed salt to deionized water and stir until undissolved crystals are present at the bottom of the solution. Place the third preform obtained in step (3) in a 0.05MPa vacuum environment, inject the above saturated salt solution, impregnate under pressure for 30 minutes, remove and dry at 80°C for 12 hours to form solid salt in the micro-nano porous structure, and obtain the fourth preform.

[0065] (5) Calcination treatment: The fourth blank is placed in a muffle furnace and then slowly heated to 600°C while continuously introducing nitrogen gas. It is then calcined at 600°C for 8 hours. Finally, it is naturally cooled to obtain a solid heat storage material with a multi-level pore structure.

[0066] The solid waste-based bilevel porous composite thermal storage material (SHS) prepared in Example 1 was subjected to performance testing. Its thermal conductivity and pore parameters are as follows: Figure 5 As shown in Table 1.

[0067] Figure 5 The thermal conductivity curves show that the solid waste-based dual-stage porous composite thermal storage material prepared in this embodiment has better thermal conductivity, which is due to its unique directional mass transfer channel design.

[0068] The pore parameters in Table 1 show that the material prepared in this embodiment has both a high total pore volume and an optimized pore size distribution (combining macroscopic channels and micro / nano pores), confirming the successful construction of the "dual-level pore" structure, which provides a structural basis for achieving high salt loading and rapid mass transfer.

[0069] Comparative Example 1

[0070] According to Table 1 and Figure 5 As can be seen, this example uses traditional solid waste-based thermal storage materials, which are prepared by traditional pressing molding and simple sintering processes. The resulting material has a single-scale pore structure, no directional channels, low mass transfer efficiency, and limited salt loading.

[0071] Comparative Example 2

[0072] According to Table 1 and Figure 5 As can be seen, this example uses commercial phase change thermal storage materials, which are prepared by microencapsulation or physical mixing processes. The resulting material structure is an encapsulated structure, in which the phase change material is encapsulated in microcapsules or a matrix. This results in high thermal resistance, low heat transfer efficiency, and high cost.

[0073] In summary, based on the above embodiments and comparative examples, the solid waste-based dual-level porous composite thermal storage material (SHS) prepared by 3D printing + high-temperature carbonization + vacuum impregnation + directional calcination migration has a dual-level porous structure (macroscopic frustum-shaped channels + micro-nano pores), and has dual-level pores and directional mass transfer performance, which makes it superior to the material in the comparative examples in terms of thermal conductivity, high salt loading and rapid mass transfer.

[0074] Table 1. Comparison of pore parameters between the solid waste-based composite thermal storage materials (SHS) prepared in Example 1 and Comparative Examples 1-2 and the materials in Comparative Examples 1 and 2.

[0075]

[0076] This disclosure proposes a solid waste-based dual-level porous structure and directional mass transfer composite thermal storage material and its preparation method, which has the following advantages compared with the prior art:

[0077] 1. This disclosure proposes for the first time the design concept of a composite thermal storage material system of "two-stage pores + directional mass transfer", which greatly improves the thermal storage performance of solid thermal storage materials.

[0078] 2. This invention uses low-grade solid waste as the main material, which is inexpensive, abundant, environmentally friendly, and has a long service life.

[0079] 3. This disclosure adopts a combination strategy of solid-state mass transfer and liquid-solid mass transfer, which avoids the problem of poor sealing in traditional liquid mass transfer processes.

[0080] 4. The multi-scale, multi-directional channel design adopted in this disclosure is conducive to achieving rapid heat diffusion.

[0081] 5. This disclosure employs a secondary pore structure to improve the heat storage density of the material.

[0082] 6. This disclosure employs a high-ion-concentration brine impregnation method to effectively improve the heat storage performance of the material.

[0083] It is understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of this disclosure, and this disclosure is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and substance of this disclosure, and these modifications and improvements are also considered to be within the scope of protection of this disclosure.

Claims

1. A method for preparing a solid waste-based dual-porosity and directional mass transfer composite thermal storage material, characterized in that, The preparation method includes: Steel slag, fly ash and binder are mixed to form a mixed slurry, and the mixed slurry is 3D printed to form a first blank with a preset columnar channel; The first green body is subjected to sintering and porosity control treatments in sequence to obtain a second green body with a micro-nano porous structure; wherein, The sintering process for the first blank includes: The first green body was sintered in an air atmosphere: the temperature was raised from room temperature to 500 °C within 3 hours and held for 5 hours; then the temperature was raised from 500 °C to 800 °C at a rate of 10 °C / min and held for 6 hours. The first blank is subjected to porosity control treatment, including: The first sintered blank was placed in a nitrogen atmosphere in a tube furnace, heated to 400 °C, held for 8 hours, and then naturally cooled to 25 °C. The above pore control sintering process was repeated twice. Through multi-scale and multi-directional channel design, staggered macro- and micro-sized frustum-shaped channels are constructed in the second blank to form a third blank with micro-nano porous structure and frustum-shaped channels; A mixed solution of sodium and magnesium salts is injected into the third preform using a vacuum impregnation method. The preform is then impregnated with a high-concentration brine solution within its micro-nano porous structure, causing partial water displacement by the brine. After drying, solid salt is formed within the micro-nano porous structure, resulting in a fourth preform. The sodium salt is sodium chloride, and the magnesium salt is magnesium sulfate. The mixed solution of sodium and magnesium salts is a saturated or near-saturated aqueous solution with a total salt mass fraction of not less than 25%. Through calcination treatment at a temperature of 500-700°C for more than 8 hours, the solid salts in the micro-nano porous structure of the fourth preform are decomposed and migrated into the frustum-shaped channels, resulting in a solid waste-based dual-level porous composite thermal storage material.

2. The preparation method according to claim 1, characterized in that, The weight ratio of steel slag, fly ash and binder is (5~7):1:

1.

3. The preparation method according to claim 1, characterized in that, The adhesive is PVA.

4. The preparation method according to claim 1, characterized in that, The staggered macro- and micro-sized frustum-shaped channels include at least two sets of frustum-shaped channels distributed in different directions.

5. The preparation method according to claim 1, characterized in that, During the process of injecting a mixed solution of sodium and magnesium salts into the third preform using a vacuum impregnation method, the vacuum level is 0.05 MPa.

6. A solid waste-based, dual-stage porous structure, directional mass transfer composite thermal storage material, characterized in that, The solid waste-based bi-level porous structure and directional mass transfer composite thermal storage material is prepared by the preparation method described in any one of claims 1 to 5.

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