Heat storage body based on cold-sintering gradient porous body and fractal microchannel and regulation method

Abstract

The application provides a heat storage body based on cold sintering gradient porous bodies and fractal microchannels and a regulation method, the heat storage body comprises, from outside to inside, a heat conduction layer, a buffer layer and a heat storage layer in sequence, the heat conduction layer, the buffer layer and the heat storage layer are respectively provided with through holes, the hole diameters of the through holes gradually decrease from outside to inside, fractal microchannels are etched in the heat storage body, and the fractal microchannels are communicated with the through holes; the heat conduction layer is composed of a cold sintering silicon carbide / graphene composite material, the buffer layer is composed of a steel slag-ceramic base composite body, and the heat storage layer is composed of a nano-limited Na2CO3-MgO phase change system. Through the fusion of the "heat conduction layer-buffer layer-heat storage layer" multi-scale hierarchical structure, the interface strong heat transfer demand is reduced, the high-temperature inactivation problem of the phase change material is effectively avoided, and the energy storage stability is improved.

Description

Technical Field

[0001] The embodiments of the present invention belong to the field of high-temperature thermal storage technology, specifically relating to a thermal storage body and control method based on cold-sintered gradient porous body and fractal microchannel. Background Technology

[0002] In the field of solid waste-based thermal energy storage and energy quality regulation, existing technologies, such as reference patents CN120199736A and CN120048809A, have achieved significant results in heat dissipation of semiconductor devices and efficient heat dissipation of semiconductor power devices. However, these technologies mainly focus on improving heat dissipation uniformity and efficiency, without fully considering the efficient utilization of solid waste resources and the cold energy injection dynamic conditioning of phase change materials. In particular, there is a significant technological gap in the integrated application of cold sintered gradient porous structures and fractal microchannel enhanced heat transfer systems.

[0003] Specifically, the reference patent CN120199736A solves the problem of uneven heat dissipation caused by the anisotropy of homogeneous materials through a composite heat dissipation stack, but fails to address the efficient utilization of phase change materials and the design of a cold energy injection dynamic conditioning system.

[0004] Although the reference patent CN120048809A proposes an efficient heat dissipation structure based on microchannel liquid cooling technology, its main goal is to solve the heat dissipation problem of high power density devices, without fully considering the utilization of solid waste resources and the cold energy injection dynamic conditioning of phase change materials. Summary of the Invention

[0005] The embodiments of the present invention aim to at least solve one of the technical problems existing in the prior art, and provide a heat storage body and control method based on cold sintered gradient porous body and fractal microchannel.

[0006] One embodiment of the present invention provides a heat storage body based on cold sintered gradient porous body and fractal microchannels. The heat storage body includes, from the outside to the inside, a thermally conductive layer, a buffer layer and a heat storage layer. The thermally conductive layer, the buffer layer and the heat storage layer are respectively provided with through holes. The pore size of the through holes decreases layer by layer from the outside to the inside. Fractal microchannels are etched inside the heat storage body and the fractal microchannels are connected to the through holes. The thermally conductive layer is composed of a cold-sintered silicon carbide / graphene composite material, the buffer layer is composed of a steel slag-ceramic matrix composite, and the heat storage layer is composed of a nano-confined Na2CO3-MgO phase change system.

[0007] In some embodiments of the present invention, the thermally conductive layer has 50-micron-sized through-holes, the buffer layer has 1-5 micron-sized through-holes, and the heat storage layer has 50-200 nanometer-sized through-holes.

[0008] In some embodiments of the present invention, the fractal microchannel has 4-7 levels of microchannels, and the diameter of each level of microchannel is 1-100 micrometers.

[0009] In some embodiments of the present invention, the total surface area to volume ratio of the fractal microchannel is greater than 1000 m² / kg.

[0010] In some embodiments of the present invention, the porosity of the heat storage body is 0.6%-99%, the porosity of the heat-conducting layer is 0.6-30%, and the open porosity of the heat-conducting layer is 10%-90%.

[0011] In some embodiments of the present invention, the porosity of the buffer layer is 30%-70%, and the open porosity of the buffer layer is 50%-90%.

[0012] In some embodiments of the present invention, a heat storage body based on cold-sintered gradient porous bodies and fractal microchannels is prepared by the following steps: Industrial solid waste is ground to 80 mesh size, and then 5 wt% nano TiO2 and 5 wt% polyvinyl alcohol binder are added for granulation. The particles were cold-sintered at 150°C and 20MPa for 8 hours to form a porous matrix containing a silicon carbide / graphene framework. The porous matrix was CT scanned, and the fractal dimension was calculated and the microchannel path was planned using MATLAB. Fractal microchannels are fabricated inside the substrate using laser etching. A substrate with fractal microchannels is cured at 800°C to obtain a heat storage body with fractal microchannels.

[0013] A second aspect of the present invention proposes an energy and mass regulation method for a thermal storage body based on cold-sintered gradient porous bodies and fractal microchannels as described in any of the above embodiments, comprising: S1. Inject the first coolant into the surface of the heat storage body and heat it to 500°C in the evaporator to generate steam for recycling; S2. If the surface temperature of the heat storage body exceeds 350°C, inject a second coolant to maintain constant temperature heat absorption; S3. When the heat storage reaches the set value, shut off the second coolant, allow it to cool naturally to 30°C, and then restart the second coolant for heat replenishment.

[0014] In some embodiments of the present invention, the first coolant is at least one of liquid ammonia, Freon, or R245fa.

[0015] In some embodiments of the present invention, the second coolant is a mixture of water, ethylene glycol, or oil.

[0016] This invention provides a solid waste-based thermal storage body and energy quality control method based on cold-sintered gradient porous bodies and fractal microchannels. It achieves synergistic optimization by integrating a multi-scale hierarchical structure of "thermal conductive layer-buffer layer-thermal storage layer": the thermal conductive layer uses a silicon carbide / graphene composite material to construct a high-speed thermal conductive network; the buffer layer forms a low-energy-consumption barrier interface with a steel slag-ceramic composite; and the thermal storage layer relies on a nano-confined Na2CO3-MgO phase change system to achieve high-capacity energy storage. The cold sintering process allows the multi-layer structure to form a gapless structure under the non-metallic melting point bonding. The interface, coupled with a multi-scale fractal microchannel design, cleverly achieves multi-directional uniform heat conduction of a porous body with a large specific surface area, significantly reducing the demand for strong heat transfer at the interface. Furthermore, a cold energy coupling conditioning strategy is adopted, which uses low-temperature steam injected into the sealed cavity to drive the automatic charging and discharging of the metastable system, effectively avoiding the problem of high-temperature deactivation of phase change materials. At the same time, silicon carbide / graphene composite conductive framework is prepared by cold sintering of blast furnace steel slag. This framework forms an efficient heat conduction path externally and internally constrains the lattice expansion and deformation space of the phase change material, comprehensively improving the energy storage stability. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the thermal storage body based on cold-sintered gradient porous body and fractal microchannel of the present invention; Figure 2 This is a schematic diagram of the etching path planning for the thermal storage body based on cold sintered gradient porous body and fractal microchannel of the present invention.

[0018] Figure label: 1. Heat-conducting layer; 2. Buffer layer; 3. Heat storage layer; 4. Fractal microchannel; 41. Primary main channel; 42. Secondary branch channel; 43. Tertiary branch channel; 44. Quaternary branch channel; 45. Fifth-level terminal channel; 46. Fractal node; 47. Coolant flow direction. Detailed Implementation

[0019] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention 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 for explaining the present invention and are not intended to limit disclosure. The described embodiments are some, but not all, of the embodiments of the present invention. Based on the described embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0020] One embodiment of the present invention provides a heat storage body based on cold sintered gradient porous body and fractal microchannels. The heat storage body includes, from the outside to the inside, a thermally conductive layer 1, a buffer layer 2 and a heat storage layer 3. The thermally conductive layer 1, the buffer layer 2 and the heat storage layer 3 are respectively provided with through holes. The pore size of the through holes decreases layer by layer from the outside to the inside. Fractal microchannels 4 are etched inside the heat storage body and are connected to the through holes. The thermally conductive layer 1 is composed of a cold-sintered silicon carbide / graphene composite material, the buffer layer 2 is composed of a steel slag-ceramic matrix composite, and the heat storage layer 3 is composed of a nano-confined Na2CO3-MgO phase change system.

[0021] This invention provides a solid waste-based thermal storage body based on cold-sintered gradient porous bodies and fractal microchannels 4. Synergistic optimization is achieved through the integration of a multi-scale hierarchical structure consisting of a "thermal conductive layer 1 - buffer layer 2 - thermal storage layer 3": the thermal conductive layer 1 utilizes a silicon carbide / graphene composite material to construct a high-speed thermal conductivity network; the buffer layer 2 forms a low-energy-consumption barrier interface using a steel slag-ceramic composite; and the thermal storage layer 3 achieves high-capacity energy storage by relying on a nano-confined Na2CO3-MgO phase change system. The cold sintering process allows the multi-layered structure to form a gapless structure under the non-metallic melting point bonding. The interface, coupled with a multi-scale fractal microchannel design, cleverly achieves multi-directional uniform heat conduction of a porous body with a large specific surface area, significantly reducing the demand for strong heat transfer at the interface. Furthermore, a cold energy coupling conditioning strategy is adopted, which uses low-temperature steam injected into the sealed cavity to drive the automatic charging and discharging of the metastable system, effectively avoiding the problem of high-temperature deactivation of phase change materials. At the same time, silicon carbide / graphene composite conductive framework is prepared by cold sintering of blast furnace steel slag. This framework forms an efficient heat conduction path on the outside and constrains the lattice expansion and deformation space of the phase change material internally, comprehensively improving the energy storage stability.

[0022] In some embodiments of the present invention, the thermally conductive layer 1 has through-holes of 50 micrometers, the buffer layer 2 has through-holes of 1-5 micrometers, and the heat storage layer 3 has through-holes of 50-200 nanometers. From the thermally conductive layer 1 to the heat storage layer 3, the number of through-holes gradually decreases, exhibiting a gradient distribution.

[0023] In some embodiments of the present invention, the porosity of the heat storage body is 0.6%-99%, the porosity of the heat-conducting layer 1 is 0.6-30%, and the open area of ​​the heat-conducting layer 1 is 10%-90%.

[0024] In some embodiments of the present invention, the buffer layer 2 is a steel slag-ceramic matrix composite or foamed steel, including but not limited to industrial solid waste such as blast furnace slag, converter slag, and steel plant sludge. The porosity of the buffer layer 2 is 30%-70%, and the open porosity of the buffer layer 2 is 50-90%.

[0025] In some embodiments of the present invention, the heat storage layer 3 is a nano-confined NaCO-MgO phase change system, in which the phase change material is confined by nanoparticles and encapsulated within MgO crystals to form a nano-confined phase change material. The phase change temperature and latent heat of the nano-confined phase change material are adjustable within the range of 300-1000K and 140-600kJ / kg, respectively.

[0026] In some embodiments of the present invention, the fractal microchannel 4 has 4-7 levels of microchannels, each level of which has a diameter of 1-100 micrometers and a total length of 500,000-10,000,000 micrometers.

[0027] In some embodiments of the present invention, the total surface area to volume ratio of the fractal microchannel 4 is greater than 1000 m² / kg.

[0028] In some embodiments of the present invention, the porous thermal storage body is a gradient structure of at least one phase change material, that is, the mass fraction of the phase change material gradually increases with the increase of the distance from the surface.

[0029] In some embodiments of the present invention, a heat storage body based on cold-sintered gradient porous bodies and fractal microchannels is prepared by the following steps: Industrial solid waste is ground to 80 mesh size, and then 5 wt% nano TiO2 and 5 wt% polyvinyl alcohol binder are added for granulation. The particles were cold-sintered at 150°C and 20MPa for 8 hours to form a porous matrix containing a silicon carbide / graphene framework. The porous matrix was CT scanned, and the fractal dimension was calculated and the microchannel path was planned using MATLAB. Fractal microchannels were fabricated inside the substrate using laser etching 4; The substrate with fractal microchannels 4 was cured at 800°C to obtain a heat storage body with fractal microchannels 4.

[0030] A second aspect of the present invention proposes an energy and mass regulation method for a thermal storage body based on cold-sintered gradient porous bodies and fractal microchannels as described in any of the above embodiments, comprising: S1. Inject the first coolant into the surface of the heat storage body and heat it to 500°C in the evaporator to generate steam for recycling; S2. If the surface temperature of the heat storage body exceeds 350°C, inject a second coolant to maintain constant temperature heat absorption; S3. When the heat storage reaches the set value, shut off the second coolant, allow it to cool naturally to 30°C, and then restart the second coolant for heat replenishment.

[0031] In some embodiments of the present invention, the first coolant is at least one of liquid ammonia, Freon, or R245fa.

[0032] In some embodiments of the present invention, the second coolant is a mixture of water, ethylene glycol, or oil.

[0033] This invention provides a solid waste-based thermal storage body and energy quality control method based on cold-sintered gradient porous bodies and fractal microchannels. It achieves synergistic optimization by integrating a multi-scale hierarchical structure of "thermal conductive layer-buffer layer-thermal storage layer": the thermal conductive layer uses a silicon carbide / graphene composite material to construct a high-speed thermal conductive network; the buffer layer forms a low-energy-consumption barrier interface with a steel slag-ceramic composite; and the thermal storage layer relies on a nano-confined Na2CO3-MgO phase change system to achieve high-capacity energy storage. The cold sintering process allows the multi-layer structure to form a gapless structure under the non-metallic melting point bonding. The interface, coupled with a multi-scale fractal microchannel design, cleverly achieves multi-directional uniform heat conduction of a porous body with a large specific surface area, significantly reducing the demand for strong heat transfer at the interface. Furthermore, a cold energy coupling conditioning strategy is adopted, which uses low-temperature steam injected into the sealed cavity to drive the automatic charging and discharging of the metastable system, effectively avoiding the problem of high-temperature deactivation of phase change materials. At the same time, silicon carbide / graphene composite conductive framework is prepared by cold sintering of blast furnace steel slag. This framework forms an efficient heat conduction path externally and internally constrains the lattice expansion and deformation space of the phase change material, comprehensively improving the energy storage stability.

[0034] Example 1 The preparation method of thermal storage body based on cold sintered gradient porous body and fractal microchannel is as follows: S1. Blast furnace slag is ball-milled and then ground into 80-mesh powder; S2. Add 5 wt.% nano TiO to the powder treated in S1 for in-situ activation and modification, and add 5 wt.% PVA to improve adhesion. After stirring, granulate. S3. Place the granules obtained in S2 into a mold for pre-pressing and then sinter them at 150°C and 20MPa for 8 hours. S4. Obtain the original porous body image of the billet obtained in S3 through CT scanning, and perform binarization and filtering using MATLAB to obtain the image shown below. Figure 1 The porous structure with fractal characteristics is shown, and then the fractal dimension of each layer is calculated using a computer program; S5. Import the data from each layer above into finite element software to perform three-dimensional microchannel modeling and simulation of the porous body, and plan the path for actual etching based on the simulation results, such as... Figure 2 As shown; S6. According to the preset etching path, use laser processing equipment to etch the final fractal microchannel microstructure on the blast furnace slag-based porous body. S7. Place the etched blast furnace slag-based porous body into a tube furnace and calcine for 60 minutes at a temperature of 800°C to obtain a solid waste-based thermal storage body with a fractal pore structure and uniformly etched fractal microchannels inside the gradient porous body.

[0035] Figure 2 The etching path includes a primary main channel 41, a secondary branch channel 42, a tertiary branch channel 43, a quaternary branch channel 44, a quinary terminal channel 45, a fractal node 46, and a coolant flow direction 47. The diameter of the primary main channel 41 is... 80-100μm, diameter of secondary branch channel 42 50-80μm, diameter of tertiary branch channel 43 20-50μm, diameter of 44-level branched channel 5-20μm, diameter of 45 for fifth-order terminal channels The self-similarity ratio of fractal node 46 is 0.618, with the coolant flowing from the inlet to the end at 47.

[0036] Table 1. Comparison of performance indicators between traditional structures and fractal channel structures

[0037] As shown in Table 1, the heat transfer performance of the fractal channel structure (280-320 W / m·K) is 133% higher than that of the traditional structure (120-150 W / m·K), which solves the "heat conduction bottleneck" problem of traditional thermal storage bodies.

[0038] Dynamic response: The thermal response time of the fractal channel (120-180 ms) is shortened by 85% compared with the traditional structure (850-1200 ms), which significantly improves the charging / releasing speed of the heat storage body.

[0039] Structural stability: The compression loss of the fractal channel (12-18 kPa) is reduced by 65% ​​compared with the traditional structure (35-45 kPa), indicating that it has stronger resistance to deformation.

[0040] Solid waste utilization: The solid waste utilization rate of fractal channel structure (82-88%) is 75% higher than that of traditional structure (45-60%), realizing the high-value utilization of solid waste such as steel slag.

[0041] Example 2 The preparation method of thermal storage body based on cold sintered gradient porous body and fractal microchannel is as follows: S1. Grind the milling waste from road and bridge engineering into 80-mesh powder; S2. Add 5 wt.% nano TiO to the powder treated in S1 for in-situ activation and modification, and add 5 wt.% PVA to improve adhesion. After stirring, granulate. S3. Place the granules obtained in S2 into a mold for pre-pressing and then sinter them at 150°C and 20MPa for 8 hours. S4. Obtain the original porous body image of the billet obtained in S3 through CT scanning, and perform binarization and filtering using MATLAB to obtain the image shown below. Figure 1 The porous structure with fractal characteristics is shown, and then the fractal dimension of each layer is calculated using a computer program; S5. Import the data from each layer above into finite element software to perform three-dimensional microchannel modeling and simulation of the porous body, and plan the path for actual etching based on the simulation results, such as... Figure 2 As shown; S6. According to the preset etching path, use laser processing equipment to etch the final fractal microchannel with fractal pore structure and uniform etching on the blast furnace slag-based porous body. S7. Place the etched blast furnace slag-based porous body into a tube furnace and calcine for 60 minutes at a temperature of 800°C to obtain a solid waste-based thermal storage body with a fractal pore structure and uniformly etched fractal microchannels inside the gradient porous body.

[0042] Example 3 The energy and mass regulation method for thermal storage bodies based on cold-sintered gradient porous bodies and fractal microchannels includes the following specific steps: S1. Place R245fa refrigerant in a vacuum insulated tank and heat it to a molten state (boiling point is 287.65K). Use a high-pressure injection pump to quickly inject the liquid R245fa into the cavity of the high-temperature differential heat exchanger and coat it on the outer surface of the solid heat storage medium, so that it absorbs heat and evaporates into a gaseous state. S2, gaseous R245fa diffuses into the entire high-temperature differential heat stage cavity to cool down and form a transient vapor-liquid mixed flow field. After all R245fa has diffused into the high-temperature differential heat stage cavity, the power supply of the heat preservation stage is turned off to stop cooling. S3. After the mixed gas is fully mixed, turn on the power of the heat preservation platform and run it at a constant power for a period of time to ensure that R245fa fully absorbs the sensible heat of the solid heat storage medium in the high temperature differential heat platform cavity and stores it to form a steady-state gas-liquid mixed flow field. S4. When heat release is required, cut off the power supply to the insulation platform and open the valve to release the gaseous R245fa back into the vacuum insulation tank. R245fa desorbs instantly upon contact with air and absorbs heat from the surrounding environment during the flow process, causing the temperature of the solid heat storage medium to rise, thus obtaining the solid waste-based heat storage body with energy quality regulation completed.

[0043] This invention relates to a solid waste-based thermal storage body and energy quality control method based on cold-sintered gradient porous bodies and fractal microchannels. By integrating gradient porous body structures, fractal microchannel-enhanced heat transfer systems, and cold energy injection-based dynamic conditioning technology, it innovatively solves the industry's problem of "declining exothermic grade." The cold-sintered gradient porous body combined with fractal microchannel design achieves efficient thermal management, while the active cold energy injection system drives metastable dynamic conditioning. With the industrialization advantages of achieving an 85% utilization rate of steel slag solid waste and a 52% reduction in overall cost, this invention provides a high-performance and economical energy quality control solution for the field of solid waste-based thermal storage bodies.

[0044] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A heat storage body based on cold-sintered gradient porous body and fractal microchannel, characterized in that, The heat storage body comprises, from the outside to the inside, a heat-conducting layer, a buffer layer, and a heat storage layer. The heat-conducting layer, the buffer layer, and the heat storage layer are each provided with through holes. The diameter of the through holes decreases layer by layer from the outside to the inside. Fractal microchannels are etched inside the heat storage body and are connected to the through holes. The thermally conductive layer is composed of a cold-sintered silicon carbide / graphene composite material, the buffer layer is composed of a steel slag-ceramic matrix composite, and the heat storage layer is composed of a nano-confined Na2CO3-MgO phase change system.

2. The heat storage body based on cold-sintered gradient porous body and fractal microchannels according to claim 1, characterized in that, The thermally conductive layer has 50-micron-sized through-holes, the buffer layer has 1-5 micron-sized through-holes, and the heat storage layer has 50-200 nanometer-sized through-holes.

3. The heat storage body based on cold-sintered gradient porous body and fractal microchannels according to claim 1, characterized in that, The fractal microchannel has 4-7 levels of microchannels, and the diameter of each level of microchannel is 1-100 micrometers.

4. The heat storage body based on cold-sintered gradient porous body and fractal microchannels according to claim 3, characterized in that, The total surface area to volume ratio of the fractal microchannels is greater than 1000 m² / kg.

5. The solid thermal energy storage body as described in claim 1, characterized in that, The porosity of the heat storage body is 0.6%-99%, the porosity of the heat-conducting layer is 0.6-30%, and the open porosity of the heat-conducting layer is 10%-90%.

6. The solid thermal energy storage body as described in claim 1, characterized in that, The porosity of the buffer layer is 30%-70%, and the open porosity of the buffer layer is 50-90%.

7. A heat storage body based on cold-sintered gradient porous body and fractal microchannel as described in any one of claims 1-6, characterized in that, Prepared by the following steps: Industrial solid waste is ground to 80 mesh size, and then 5 wt% nano TiO2 and 5 wt% polyvinyl alcohol binder are added for granulation. The particles were cold-sintered at 150°C and 20MPa for 8 hours to form a porous matrix containing a silicon carbide / graphene framework. The porous matrix was CT scanned, and the fractal dimension was calculated and the microchannel path was planned using MATLAB. Fractal microchannels are fabricated inside the substrate using laser etching. A substrate with fractal microchannels is cured at 800°C to obtain a heat storage body with fractal microchannels.

8. A method for energy and mass regulation of a thermal storage body based on cold-sintered gradient porous body and fractal microchannel as described in any one of claims 1-7, characterized in that, include: S1. Inject the first coolant into the surface of the heat storage body and heat it to 500°C in the evaporator to generate steam for recycling; S2. If the surface temperature of the heat storage body exceeds 350°C, inject a second coolant to maintain constant temperature heat absorption; S3. When the heat storage reaches the set value, shut off the second coolant, allow it to cool naturally to 30°C, and then restart the second coolant for heat replenishment.

9. The energy quality regulation method as described in claim 8, characterized in that, The first coolant is at least one of liquid ammonia, Freon, or R245fa.

10. The energy quality control method as described in claim 8, characterized in that, The second coolant is a mixture of water, ethylene glycol, or oil.

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