A new type of pervious concrete base phase change energy storage composite material
By filling the permeable concrete skeleton layer with phase change material and sealing it with epoxy resin, the contradiction between energy storage and mechanical properties of phase change concrete was resolved, achieving stable encapsulation of phase change material and improvement of mechanical properties.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HENAN UNIVERSITY OF TECHNOLOGY
- Filing Date
- 2026-05-13
- Publication Date
- 2026-07-31
AI Technical Summary
Existing phase change concrete technology suffers from the trade-off between energy storage and mechanical properties, and phase change materials are prone to leakage, resulting in insufficient stability during long-term service.
The structure consists of a permeable concrete skeleton layer, a phase change material filling layer, and a surface sealing layer. The permeable concrete skeleton layer is a three-dimensional interconnected pore network formed by coarse aggregate bonded by point contact with cementing material. The phase change material is filled in the pores, and the surface sealing layer is sealed with epoxy resin. The encapsulation is achieved through a vacuum injection process.
It achieves simultaneous improvement in load-bearing capacity and energy storage function, solves the leakage problem of phase change materials, and improves the long-term service stability and mechanical properties of materials.
Smart Images
Figure CN122483758A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of composite material technology, and specifically to a novel permeable concrete-based phase change energy storage composite material. Background Technology
[0002] Phase change energy storage technology utilizes the latent heat of solid-liquid phase change in organic phase change materials to store and release heat. This effectively mitigates temperature fluctuations within building envelopes and infrastructure, significantly reducing the operational load and energy consumption of building temperature control systems. Furthermore, it enables active snow and ice removal in transportation infrastructure such as road and bridge decks and airport runways, significantly improving the freeze-thaw resistance and durability of concrete structures. It represents a cutting-edge core technology in the field of building energy conservation and infrastructure functional upgrades. Phase change energy storage concrete, in particular, deeply integrates energy storage functionality with building structural materials, achieving structural-functional integration. It requires no additional building or facility space and can be simultaneously adapted to diverse scenarios, including new construction, renovation of existing buildings, and snow and ice removal and freeze-thaw protection for infrastructure. Possessing extremely high engineering application value, it has become a key area of research and development in the industry.
[0003] Currently, the mainstream technical routes for phase change energy storage concrete are mainly divided into three categories. The first category is the microcapsule encapsulation and incorporation method. This route encapsulates phase change materials into micron-sized microcapsules using polymers and then directly incorporates them into the concrete matrix as functional admixtures. This is currently the most widely researched technical route in the industry. However, this method has significant technical bottlenecks: there is a significant stiffness difference between the microcapsule shell and the cement paste matrix, which easily leads to stress concentration at the interface under load, inducing the propagation of microcracks and causing significant deterioration of the mechanical properties of the concrete; moreover, the microcapsule dosage is strongly negatively correlated with the concrete strength, and the higher the dosage, the more severe the strength attenuation. Typically, when the microcapsule dosage exceeds 10%, the compressive strength of the concrete can decrease by more than 30%, making it difficult to synergistically improve energy storage density and mechanical properties; at the same time, the microcapsule shell is easily damaged under the highly alkaline environment of concrete hydration and the action of load cycles, resulting in a high risk of leakage of the internal phase change material and poor long-term service stability. The second type is the porous aggregate adsorption method. To alleviate the mechanical degradation problem of the microencapsulation method, the industry uses lightweight porous aggregates such as expanded perlite, ceramsite, and expanded vermiculite to adsorb phase change materials and then replace ordinary aggregates in concrete to prepare energy storage materials. Although this approach improves the dispersibility of phase change materials to some extent, it still does not solve the core problems: the strength of the porous carrier itself is much lower than that of ordinary crushed stone aggregate, which directly leads to a significant decrease in the strength benchmark of concrete after replacement; at the same time, there is still a stiffness mismatch between porous aggregates and cement paste matrix, the interface transition zone is weak, and interface debonding and aggregate breakage are prone to occur under load, further aggravating the deterioration of mechanical properties; in addition, the surface encapsulation effect of porous aggregates is limited, and premature leakage of phase change materials is prone to occur during mixing. After temperature cycling, the encapsulation layer is prone to cracking, and the leakage problem cannot be completely solved, resulting in a continuous decline in long-term energy storage efficiency. The third type is the direct incorporation method. This route has the simplest process, directly incorporating the phase change material into the concrete mixture and casting it into shape. However, it has extremely prominent drawbacks: the liquid phase change material has very poor compatibility with cement hydration products, which will seriously hinder the cement hydration process and lead to a significant decrease in concrete strength; moreover, there is no effective encapsulation method, and the phase change material is very easy to leak from the pores of the concrete after melting. After multiple temperature cycles, the loss rate of the phase change material can reach more than 20%, and the energy storage efficiency drops sharply. It only remains at the laboratory research stage, and its engineering promotion faces great challenges.
[0004] All technical approaches introduce phase change materials or their carriers as weak phase dispersions into the concrete matrix, inevitably disrupting the structural continuity of the concrete matrix and resulting in a significant reduction in the overall mechanical properties of the material. Energy storage density and load-bearing capacity are always in a trade-off relationship, making it difficult to simultaneously achieve synergistic improvement of both. At the same time, existing technologies have not formed a stable and reliable anti-leakage encapsulation system for phase change materials, which cannot guarantee the energy storage stability of the material during long-term service. Summary of the Invention
[0005] The purpose of this invention is to provide a novel permeable concrete-based phase change energy storage composite material to solve the problems of the trade-off between energy storage and mechanical properties in existing phase change concrete, easy leakage of phase change materials, and insufficient long-term service stability.
[0006] To achieve the above objectives, the present invention provides the following technical solution:
[0007] According to a first aspect of this disclosure, a novel permeable concrete-based phase change energy storage composite material is proposed, comprising a permeable concrete skeleton layer, a phase change material filling layer, and a surface sealing layer.
[0008] The permeable concrete skeleton layer is a rigid skeleton with a three-dimensional interconnected pore network formed by point contact bonding of coarse aggregate with cementing materials. The designed porosity of the permeable concrete skeleton layer is 15% to 35%.
[0009] The phase change material filling layer is an organic phase change material filling the three-dimensional interconnected pores of the permeable concrete skeleton layer. When the organic phase change material is in solid state, the filling saturation in the three-dimensional interconnected pores is 60% to 80%.
[0010] The surface sealing layer is an epoxy resin sealing layer, which completely covers the entire outer surface of the permeable concrete skeleton layer and is used to seal all open pores on the surface of the permeable concrete skeleton layer.
[0011] Furthermore, the raw material mix ratio of the permeable concrete skeleton layer is: 290 parts by weight of cement, 1650 parts by weight of coarse aggregate, 85 parts by weight of water, and 10 parts by weight of reinforcing agent, with a water-cement ratio of 0.293.
[0012] Furthermore, the organic phase change material is capable of solid-liquid transformation, and the organic phase change material is a paraffin-based phase change material. The phase change temperature of the paraffin-based phase change material is 20℃~60℃, and the latent heat of phase change is not less than 150J / g.
[0013] Furthermore, the surface sealing layer is prepared using a two-component epoxy resin sealant, wherein the mass ratio of component A to component B of the two-component epoxy resin sealant is 2:1, and the application rate of the epoxy resin sealant on the outer surface of the permeable concrete skeleton layer is 0.20 g / cm². 2 ~0.40g / cm 2 .
[0014] Furthermore, the epoxy resin sealant is applied at a rate of 0.23 g / cm² per unit area on the outer surface of the permeable concrete skeleton layer. 2 ~0.35g / cm 2 .
[0015] According to the second aspect of this disclosure, a method for preparing a novel permeable concrete-based phase change energy storage composite material is proposed for preparing the phase change energy storage composite material of the first aspect, comprising the following steps:
[0016] S1. Mix coarse aggregate, cementitious material, reinforcing agent and water evenly according to the design mix ratio. The water-cement ratio of the design mix ratio is 0.25 to 0.35, the amount of cementitious material is 250 to 350 parts by weight, the amount of coarse aggregate is 1600 to 1700 parts by weight, and the amount of reinforcing agent is 8 to 12 parts by weight. After mixing, prepare specimens by tamping or vibration molding process, and cure them according to standard to the design age to obtain a permeable concrete skeleton with a three-dimensional interconnected pore network.
[0017] S2. Leave the top surface of the permeable concrete skeleton as the grouting surface without treatment, and evenly apply epoxy resin sealant to all other outer surfaces, and cure at room temperature until fully hardened to form a pre-sealed layer.
[0018] S3. Heat the organic phase change material to 10℃~20℃ above its melting point until it is completely liquefied. Place the pre-sealed permeable concrete skeleton with the injection surface facing up in the vacuum injection equipment, evacuate to a vacuum degree of -0.08MPa~-0.10MPa and maintain the pressure. Under negative pressure, inject the liquid organic phase change material into the interconnecting pores of the permeable concrete skeleton through the injection surface. After the injection is completed, slowly release the vacuum and keep it at normal pressure for heat preservation.
[0019] S4. Cool the permeable concrete skeleton after it has been poured until the organic phase change material has completely solidified, apply epoxy resin sealant to the top surface of the poured surface to seal the surface pores, and obtain the new permeable concrete-based phase change energy storage composite material after curing.
[0020] Furthermore, in step S3, the pressure holding time after vacuuming is 4 hours; during the atmospheric pressure static heat preservation process, the liquid organic phase change material is supplemented and filled with interconnected pores by gravity and capillary force.
[0021] Furthermore, the continuous porosity of the permeable concrete skeleton was determined using the vacuum saturation method. The specific steps included: soaking the permeable concrete in water for 24 hours, placing it in a vacuum saturation device filled with clean water and evacuating it for 4 hours, transferring the specimen to a water bucket and weighing the suspended mass of the specimen, removing the specimen, and then drying it in a constant temperature oven at 90°C. The measured continuous porosity is expressed as:
[0022]
[0023] in, This indicates the suspension mass of the specimen in pure water after vacuum saturation with water; This indicates the absolute dry mass of the permeable concrete specimen after it has been dried to constant weight and cooled to room temperature. This indicates the overall volume of the permeable concrete specimen. This indicates the interconnected porosity of the permeable concrete skeleton. This indicates the density of water.
[0024] Furthermore, in step S3, the specific steps of encapsulation followed by filling include: first calculating the outer surface area of the top surface of the specimen, according to 0.23 g / cm³. 2 ~0.35g / cm 2 Prepare the required amount of epoxy resin sealant for each unit, apply the epoxy resin sealant to the specimen to cover its surface pores, and then vacuum infuse for 4 hours. This allows the organic phase change material to enter the interconnected pore network from the top surface of the specimen through the internal and external pressure difference generated by the vacuum infusion. Then, remove the specimen horizontally from the organic phase change material container. If no organic phase change material flows out from the surface coated with epoxy resin sealant, the infusion is successful, and a composite specimen is obtained.
[0025] Furthermore, after the epoxy resin sealant is applied to the specimen, the mass of the specimen after applying the epoxy resin sealant is weighed, and the mass of the composite specimen after successful infusion of the organic phase change material is weighed. The composite specimen is placed in a low-temperature environment chamber for 6 hours to allow the organic phase change material in the specimen to completely solidify. The infusion rate of the organic phase change material in solid state is calculated and expressed as follows:
[0026]
[0027] The infusion rate of organic phase change materials in the solid state is expressed as:
[0028]
[0029] in, This indicates the oven-dry weight of the permeable concrete skeleton before grouting after pre-sealing; This indicates the total mass of the composite specimen after the organic phase change material has been poured in and solidified. This represents the density of organic phase change materials in the solid state. This indicates the density of the organic phase change material in its liquid state.
[0030] Compared with existing technologies, this invention provides a novel permeable concrete-based phase change energy storage composite material. By using the three-dimensional interconnected pores of permeable concrete as a dedicated storage space for the phase change material, the organic phase change material within the pores, regardless of its solid or liquid state, can provide effective lateral constraint for the skeleton, thereby further enhancing the compressive strength of the composite material compared to plain permeable concrete. This achieves a simultaneous improvement in load-bearing capacity and energy storage function. By employing a reverse process of pre-sealing followed by vacuum injection, the problem of sealant adhesion failure and organic phase change material leakage caused by organic phase change material contamination of the concrete surface is fundamentally solved. Furthermore, the vacuum saturation method is used to correct the interconnected porosity test error, allowing for precise and stable control of the phase change material injection rate. Simultaneously, performance can be designed on demand through mix ratio adjustment, making it suitable for various building engineering scenarios. The raw materials are readily available, the process is simple, and it possesses excellent value for large-scale promotion and potential for building energy conservation applications. Attached Figure Description
[0031] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.
[0032] Figure 1 This is a schematic diagram illustrating the structure and core design principle of the novel permeable concrete-based phase change energy storage composite material of the present invention.
[0033] Figure 2 The images show CT slices of the composite material at different heights and peak stress-strain diagrams of the composite material under different paraffin infusion states. Ref-PC is plain permeable concrete, PC-E is permeable concrete coated with epoxy resin, and PC-PCM(L) and PC-PCM(S) are permeable concrete-based phase change energy storage composite materials with liquid and solid paraffin, respectively.
[0034] Figure 3 This is a flowchart illustrating the core process for preparing the composite material of the present invention.
[0035] Figure 4 This is a schematic diagram illustrating the failure principle of the pre-filling and post-sealing process in existing technologies.
[0036] Figure 5 The graph shows the relationship between the modified interconnected porosity and the paraffin injection rate for permeable concrete skeletons with different designed porosities according to the present invention.
[0037] Figure 6 Figure A shows a comparison of the uniaxial compressive stress-strain curves and corresponding failure modes of the composite material of the present invention and the control group specimens. Figure B is a schematic diagram of the multiphase microstructure characterization and three-dimensional reconstruction of the composite material of the present invention by industrial CT scanning. Detailed Implementation
[0038] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.
[0039] Example 1:
[0040] This invention provides a novel permeable concrete-based phase change energy storage composite material, comprising a permeable concrete skeleton layer, a phase change material filling layer, and a surface sealing layer;
[0041] The permeable concrete skeleton layer is a rigid skeleton with a three-dimensional interconnected pore network formed by point-contact bonding of coarse aggregate with cementitious materials. The designed porosity of the permeable concrete skeleton layer is 15%–35%. The raw material mix proportions of the permeable concrete skeleton layer are: 290 parts by weight of cement, 1650 parts by weight of coarse aggregate, 85 parts by weight of water, and 10 parts by weight of reinforcing agent, with a water-cement ratio of 0.293, as shown in the table below.
[0042]
[0043] The phase change material filling layer is an organic phase change material that fills the three-dimensional interconnected pores of the permeable concrete skeleton layer. When the organic phase change material is in solid state, the filling saturation in the three-dimensional interconnected pores is 60% to 80%. The organic phase change material is a paraffin-based phase change material with a phase change temperature of 20℃ to 60℃ and a latent heat of phase change of not less than 150J / g.
[0044] The surface sealing layer is an epoxy resin sealing layer that completely covers the entire outer surface of the permeable concrete skeleton layer, sealing all open pores on the surface. This surface sealing layer is prepared using a two-component epoxy resin sealant, with a component A to component B mass ratio of 2:1. The application rate of the epoxy resin sealant on the outer surface of the permeable concrete skeleton layer is 0.20 g / cm². 2 ~0.40g / cm 2 .
[0045] The epoxy resin sealant was applied at a rate of 0.23 g / cm² per unit area on the outer surface of the permeable concrete skeleton layer. 2 ~0.35g / cm 2 The relevant parameters of its two-component epoxy resin sealant are as follows:
[0046]
[0047] Epoxy resin is used to seal the surface pores of permeable concrete except for the top surface. Liquid phase change material is then injected into the internal interconnected pores through a vacuum injection process. After the phase change material solidifies, the top pores are sealed, forming a new type of permeable concrete-based phase change energy storage composite material, which simultaneously improves mechanical properties and energy storage density.
[0048] And as shown in the experiment and the table below:
[0049] Specimen type <![CDATA[Peak strain × 10 -6 > Compressive strength (MPa) Strength improvement rate (%) Effective thermal conductivity Paraffin Infusion Rate (%) Plain permeable concrete Ref-PC 2094.2 16.34 - 0.8867 — Epoxy resin sealed permeable concrete PC-E 1965.7 17.66 8.07% - — Liquid paraffin-filled composite material PC-PCM (L) 2314.3 21.13 29.31% - 92% (liquid) Solid paraffin-filled composite material PC-PCM (S) 2106.3 24.89 52.33% 1.0661 67% (solid-state)
[0050] This indicates that the phase change material (paraffin) contained in the pores, whether in a solid or liquid state, can provide effective lateral restraint for the porous skeleton, increasing the overall compressive strength by an additional 5–10 MPa. The compressive strength of plain permeable concrete Ref-PC is 16.34 MPa, serving as a benchmark. After epoxy resin sealing treatment (PC-E), the compressive strength slightly increased to 17.66 MPa, an increase of only 8.07%, indicating that the epoxy resin surface sealing layer has a limited direct contribution to the matrix strength; its main function is protection rather than reinforcement. In contrast, the compressive strength of the liquid paraffin-filled composite material (PC-PCM(L)) reached 21.13 MPa, an increase of 29.31% compared to the benchmark, indicating that the hydrostatic restraint provided by the liquid paraffin within the pores has a significant lateral support effect on the skeleton structure. More significantly, the compressive strength of the solid paraffin-filled composite material (PC-PCM(S)) reached 24.89 MPa, an improvement of 52.33% compared to the benchmark. This result fully demonstrates that solid paraffin can provide stronger rigidity and stress transfer mechanism than liquid paraffin, which significantly enhances the load-bearing capacity of the composite material.
[0051] As for the trend of peak strain data, the peak strain of plain permeable concrete Ref-PC is 2094.2×10⁻⁶. -6 After epoxy resin sealing (PC-E), the peak strain decreased slightly to 1965.7 × 10⁻⁶. -6 The decrease was approximately 6.1%, indicating that the rigid constraint of the surface sealing layer slightly limited the material's deformation capacity. The peak strain of the liquid paraffin-filled composite material (PC-PCM(L)) increased to 2314.3 × 10⁻⁶. -6 The 10.5% improvement over the baseline indicates that the fluidity of liquid paraffin allows for greater deformation space before peak stress, resulting in better ductility. The peak strain of the solid paraffin-filled composite (PC-PCM(S)) is 2106.3 × 10⁻⁶. -6The value was close to the baseline, with an increase of only 0.6%, indicating that while the rigid constraint of solid paraffin significantly improved strength, it also limited the material's deformation capacity, keeping its peak strain at a relatively low level. This phenomenon reflects the different mechanisms by which solid and liquid phase change materials provide lateral constraint: liquid paraffin provides uniform lateral support through hydrostatic pressure, while solid paraffin provides stronger but more limited constraint through rigid contact.
[0052] The thermal conductivity of plain permeable concrete (Ref-PC) is 0.8867 W / (m·K), which is typical for porous concrete materials. The effective thermal conductivity of solid paraffin-filled composite material PC-PCM(S) is increased to 1.0661 W / (m·K), a 20.2% improvement over the baseline. This improvement is mainly due to the inherent thermal conductivity of paraffin phase change materials and the improved heat transfer path resulting from the close contact between the paraffin and the pores in the framework.
[0053] The infilling rate of solid paraffin-filled composite PC-PCM (S) was 67%, while that of liquid paraffin-filled composite PC-PCM (L) reached 92%. This difference lies in the phase transition of the phase change material. Liquid paraffin can flow fully and fill every corner of the pore network during vacuum infilling; while solid paraffin shrinks in volume after cooling and solidification, and its rigidity restricts its flowability within the pores.
[0054] Furthermore, this composite material can not only adjust the skeleton topology through the mixing ratio to achieve on-demand configuration of load-bearing and energy storage capacity, but also has the advantages of simple process and readily available raw materials, which is conducive to large-scale engineering promotion.
[0055] Example 2:
[0056] This invention also provides a method for preparing a novel permeable concrete-based phase change energy storage composite material, comprising the following steps:
[0057] S1. Mix coarse aggregate, cementitious material, reinforcing agent and water evenly according to the design mix ratio. The water-cement ratio of the design mix ratio is 0.25 to 0.35, the amount of cementitious material is 250 to 350 parts by weight, the amount of coarse aggregate is 1600 to 1700 parts by weight, and the amount of reinforcing agent is 8 to 12 parts by weight. After mixing, prepare specimens by tamping or vibration molding process, and cure them according to standard to the design age to obtain a permeable concrete skeleton with a three-dimensional interconnected pore network.
[0058] S2. Leave the top surface of the permeable concrete skeleton as the grouting surface without treatment, and apply epoxy resin sealant evenly to all other outer surfaces. Let it cure at room temperature until it is fully hardened to form a pre-sealed layer.
[0059] S3. Heat the organic phase change material to 10℃~20℃ above its melting point until it is completely liquefied. Place the pre-sealed permeable concrete skeleton with the injection surface facing up in the vacuum injection equipment, evacuate to a vacuum degree of -0.08MPa~-0.10MPa and maintain the pressure. Under negative pressure, inject the liquid organic phase change material into the interconnecting pores of the permeable concrete skeleton through the injection surface. After the injection is completed, slowly release the vacuum and keep it at normal pressure for heat preservation.
[0060] Specifically, the pressure holding time after vacuuming is 4 hours; during the static heat preservation process at normal pressure, the liquid organic phase change material is supplemented and filled with interconnected pores by gravity and capillary force.
[0061] Because conventional immersion methods underestimate the volume of interconnected pores due to surface tension limitations, the calculated grouting rate often exceeds the 100% limit. Therefore, in this embodiment, the interconnected porosity of the permeable concrete skeleton is determined using a vacuum saturation method under the same conditions as actual grouting. The specific steps include: immersing the permeable concrete in water for 24 hours, placing it in a vacuum saturation device filled with clean water and evacuating it for 4 hours, transferring the specimen to a water bucket and weighing the suspended mass, removing the specimen, and drying it in a 90°C constant temperature oven. The measured continuous porosity is expressed as:
[0062]
[0063] in, This indicates the suspension mass of the specimen in pure water after vacuum saturation with water; This indicates the absolute dry mass of the permeable concrete specimen after it has been dried to constant weight and cooled to room temperature. This indicates the overall volume of the permeable concrete specimen. This indicates the interconnected porosity of the permeable concrete skeleton. This indicates the density of water.
[0064] In step S3, the specific steps of encapsulation followed by potting include: first calculating the outer surface area of the specimen excluding the top surface, according to 0.23 g / cm³. 2 ~0.35g / cm 2 Prepare the required amount of epoxy resin sealant for each unit, apply the epoxy resin sealant to the specimen to cover its surface pores, and then vacuum infuse for 4 hours to allow the organic phase change material to be pressed into the interconnected pore network through the top surface of the specimen. Then, remove the specimen horizontally from the organic phase change material container. If no organic phase change material flows out of the specimen surface after applying epoxy resin sealant, the infusion is successful and a composite specimen is obtained.
[0065] After applying epoxy resin sealant to the specimen, the mass of the specimen after applying epoxy resin sealant is measured. After successful infusion, the mass of the composite specimen after adding organic phase change material is also measured. The composite specimen is placed in a low-temperature chamber for 6 hours to allow the organic phase change material to completely solidify. The infusion rate of the organic phase change material is calculated and expressed as follows:
[0066] (Liquid)
[0067] (Solid state)
[0068] in, This indicates the oven-dry weight of the permeable concrete skeleton before grouting after pre-sealing; This indicates the total mass of the composite specimen after the organic phase change material has been poured in and solidified. and This indicates the density of the organic phase change material in its liquid and solid states, respectively.
[0069] S4. The permeable concrete skeleton after pouring is cooled naturally or at a controlled rate until the organic phase change material is completely solidified. Epoxy resin sealant is applied to the top pouring surface to seal the surface pores. After curing, a new type of permeable concrete-based phase change energy storage composite material is obtained.
[0070] Regarding mechanical response characteristics, uniaxial compression tests were conducted on permeable concrete-based phase change energy storage composite materials under different phase states using a displacement-controlled mode, and stress-strain curves were obtained. The results show that paraffin wax provides effective lateral constraint and stress transfer for filling the pores in the skeleton under both phase states, and the rigid constraint provided by solid paraffin wax is stronger than the hydrostatic constraint provided by liquid paraffin wax. In terms of multiphase microstructure characterization, industrial CT scans of the cast specimens were performed, obtaining high-resolution tomographic images of the aggregate-paraffin-pore three phases. Gray-scale thresholding and phase domain identification were completed, achieving spatial separation and three-dimensional visualization reconstruction of the microstructure.
[0071] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.
Claims
1. A novel permeable concrete-based phase change energy storage composite material, characterized in that, It includes a permeable concrete skeleton layer, a phase change material filling layer, and a surface sealing layer; The permeable concrete skeleton layer is a rigid skeleton with a three-dimensional interconnected pore network formed by point contact bonding of coarse aggregate with cementing materials. The designed porosity of the permeable concrete skeleton layer is 15% to 35%. The phase change material filling layer is an organic phase change material filling the three-dimensional interconnected pores of the permeable concrete skeleton layer. When the organic phase change material is in solid state, the filling saturation in the three-dimensional interconnected pores is 60% to 80%. The surface sealing layer is an epoxy resin sealing layer, which completely covers the entire outer surface of the permeable concrete skeleton layer and is used to seal all open pores on the surface of the permeable concrete skeleton layer.
2. The novel permeable concrete-based phase change energy storage composite material according to claim 1, characterized in that, The raw material mix ratio of the permeable concrete skeleton layer is: 290 parts by weight of cement, 1650 parts by weight of coarse aggregate, 85 parts by weight of water, and 10 parts by weight of reinforcing agent, with a water-cement ratio of 0.
293.
3. The novel permeable concrete-based phase change energy storage composite material according to claim 1, characterized in that, The organic phase change material is capable of solid-liquid transformation. The organic phase change material is a paraffin-based phase change material. The phase change temperature of the paraffin-based phase change material is 5℃~60℃, and the latent heat of phase change is not less than 150J / g.
4. The novel permeable concrete-based phase change energy storage composite material according to claim 1, characterized in that, The surface sealing layer is prepared using a two-component epoxy resin sealant. The mass ratio of component A to component B in the two-component epoxy resin sealant is 2:
1. The application rate of the epoxy resin sealant on the outer surface of the permeable concrete skeleton layer is 0.20 g / cm². 2 ~0.40g / cm 2 .
5. The novel permeable concrete-based phase change energy storage composite material according to claim 4, characterized in that, The epoxy resin sealant is applied at a rate of 0.23 g / cm² per unit area on the outer surface of the permeable concrete skeleton layer. 2 ~0.35g / cm 2 .
6. A method for preparing a novel permeable concrete-based phase change energy storage composite material as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Mix coarse aggregate, cementitious material, reinforcing agent and water evenly according to the design mix ratio. The water-cement ratio of the design mix ratio is 0.25 to 0.35, the amount of cementitious material is 250 to 350 parts by weight, the amount of coarse aggregate is 1600 to 1700 parts by weight, and the amount of reinforcing agent is 8 to 12 parts by weight. After mixing, prepare specimens by tamping or vibration molding process, and cure them according to standard to the design age to obtain a permeable concrete skeleton with a three-dimensional interconnected pore network. S2. Leave the top surface of the permeable concrete skeleton as the grouting surface without treatment, and evenly apply epoxy resin sealant to all other outer surfaces, and cure at room temperature until fully hardened to form a pre-sealed layer. S3. Heat the organic phase change material to 10℃~20℃ above its melting point until it is completely liquefied. Place the pre-sealed permeable concrete skeleton with the injection surface facing up in the vacuum injection equipment, evacuate to a vacuum degree of -0.08MPa~-0.10MPa and maintain the pressure. Under negative pressure, inject the liquid organic phase change material into the interconnecting pores of the permeable concrete skeleton through the injection surface. After the injection is completed, slowly release the vacuum and keep it at normal pressure for heat preservation. S4. Cool the permeable concrete skeleton after it has been poured until the organic phase change material has completely solidified, apply epoxy resin sealant to the top surface of the poured surface to seal the surface pores, and obtain the new permeable concrete-based phase change energy storage composite material after curing.
7. The preparation method of a novel permeable concrete-based phase change energy storage composite material according to claim 6, characterized in that, In step S3, the pressure holding time after vacuuming is 4 hours; during the static heat preservation process at normal pressure, the liquid organic phase change material is supplemented and filled with interconnected pores by gravity and capillary force.
8. The preparation method of a novel permeable concrete-based phase change energy storage composite material according to claim 6, characterized in that, The continuous porosity of the permeable concrete skeleton was determined using the vacuum saturation method. The specific steps included: soaking the permeable concrete in water for 24 hours, placing it in a vacuum saturation device filled with clean water and evacuating it for 4 hours, transferring the specimen to a water bucket and weighing the suspended mass of the specimen, removing the specimen, and then drying it in a constant temperature oven at 90℃. The measured continuous porosity is expressed as: in, This indicates the suspension mass of the specimen in pure water after vacuum saturation with water; This indicates the absolute dry mass of the permeable concrete specimen after it has been dried to constant weight and cooled to room temperature. This indicates the overall volume of the permeable concrete specimen. This indicates the interconnected porosity of the permeable concrete skeleton. This indicates the density of water.
9. The preparation method of a novel permeable concrete-based phase change energy storage composite material according to claim 6, characterized in that, In step S3, the specific steps of encapsulation followed by potting include: first calculating the outer surface area of the top surface of the specimen, based on 0.23 g / cm³. 2 ~0.35g / cm 2 Prepare the required amount of epoxy resin sealant for each unit, apply the epoxy resin sealant to the specimen to cover its surface pores, and then vacuum infuse for 4 hours to allow the organic phase change material to enter the interconnected pore network from the top pores of the specimen through the generated internal and external pressure difference. Then, remove the specimen horizontally from the organic phase change material container. If no organic phase change material flows out from the surface coated with epoxy resin sealant, the infusion is successful and a composite specimen is obtained.
10. The preparation method of a novel permeable concrete-based phase change energy storage composite material according to claim 9, characterized in that, After the epoxy resin sealant is applied to the specimen, the mass of the specimen after applying the epoxy resin sealant is measured. After successful infusion, the mass of the composite specimen after adding the organic phase change material is also measured. The composite specimen is placed in a low-temperature chamber for 6 hours to allow the organic phase change material in the specimen to completely solidify. The infusion rate of the organic phase change material in solid state is calculated and expressed as follows: The infusion rate of organic phase change materials in the solid state is expressed as: in, This indicates the oven-dry weight of the permeable concrete skeleton before grouting after pre-sealing; This indicates the total mass of the composite specimen after the organic phase change material has been poured in and solidified. This represents the density of organic phase change materials in the solid state. This indicates the density of the organic phase change material in its liquid state.