Geopolymer straw phase change block and preparation method and application thereof

Abstract

The present application relates to a kind of geopolymer straw phase change block and its preparation method and application, including the following weight parts raw materials: straw powder 25%-35% of shaped phase change heat storage material particle, 15%-25% of shaped organic phase change heat storage material of fly ash, 10%-20% of fly ash, 10%-20% of metakaolin, 10%-15% of alkali activator, 0.1-1.0% of coupling agent, 0.9%-2.5% of polymer cementing material, 9%-12% of water.The present application utilizes agricultural waste straw to make suitable phase change wall for sunlight greenhouse, not easy to leak, encapsulation is stable, the present application phase change wall is applied in greenhouse sunlight greenhouse, when the lowest outdoor temperature can reach-33 ℃ below, it can also realize the lowest indoor temperature is located 12.5 above.

Description

Technical Field

[0001] This invention relates to phase change blocks and their preparation methods, specifically to a geopolymer straw phase change block and its preparation method. Background Technology

[0002] In 2023, my country's main crop straw production will reach 1.1 billion tons, with a stock of 7.8 billion tons. The resource utilization of straw is of great significance for reducing carbon emissions in rural areas, promoting rural revitalization, and helping to achieve the "dual carbon" goals.

[0003] Solar greenhouses are agricultural facilities used for off-season cultivation of vegetables and fruit trees. They are characterized by high efficiency, energy saving, and low cost, and energy is the core issue of facility agriculture. The principle of a solar greenhouse is that the walls or soil can release the heat stored during the day into the room at night, which helps maintain the growth of crops inside. The heat released by the greenhouse walls at night is only 10%-25% of the heat absorbed during the day, and most of the remaining heat is lost through the walls or other structural media. Without fossil fuel facilities such as coal, straw burning, natural gas, or electricity to provide energy (heat source), the heat storage capacity of solar greenhouses is greatly reduced, or the heat storage capacity is too small to meet the temperature requirements for the growth of fruits and vegetables (especially eggplant), resulting in a significant decrease in the economic benefits of agricultural facilities and thus causing resource waste. At present, most solar greenhouse wall materials are sensible heat materials. Due to the low energy density and thermal conductivity of energy storage materials, sensible heat energy storage technology has disadvantages such as short energy storage cycle, small heat storage capacity, and inability to maintain a constant temperature, which cannot meet the application requirements of high-temperature summer and low-temperature winter heating energy storage systems. Therefore, in addition to utilizing the heat storage function of greenhouse soil, it is also necessary to improve the air temperature in solar greenhouses by enhancing both the heat storage and insulation properties of the greenhouse walls. Using straw for building insulation can save up to approximately 51 MJ / (kg·a) during the heating season. Under the same insulation effect, the total energy consumption and CO2 emissions during the production process of straw-based materials are lower than those of insulation materials such as polystyrene foam, demonstrating excellent energy-saving and emission-reduction effects. However, the low compressive strength, lack of waterproofing and fire resistance of current straw building materials limit their application.

[0004] Phase change energy storage materials (PCS) are materials with energy storage capabilities that store energy through a phase change process and release it when needed. Encapsulation design is a crucial step in protecting PCS materials and improving their performance. However, PCS materials suffer from limitations such as low thermal conductivity, susceptibility to leakage and corrosion, resulting in poor stability and short cycle life. Furthermore, PCS materials are prone to seeping out of walls during phase change, leading to reduced temperature regulation and causing wall contamination and corrosion.

[0005] The main solution is to encapsulate the phase change material (PCM). The most effective method is to prepare solid-liquid PCM such as n-alkanes and hydrated crystalline salts into microcapsule PCM through microencapsulation technologies such as interfacial polymerization and in-situ polymerization. However, this process is complex and expensive. Additionally, it is necessary to address the volume expansion and contraction of the encapsulated PCM to avoid stress concentration and damage, while simultaneously enhancing the thermal conductivity of the composite PCM. Porous framework encapsulation refers to using a porous medium with a large specific surface area as the framework carrier material, utilizing capillary forces and surface adsorption effects to imprison the liquid PCM within the pores, making it difficult for the material to leak out even during phase change. Using porous materials such as expanded graphite, kaolin, silica, and gypsum to adsorb PCM and prepare shaped PCM exhibits good shape stability and a simple process, exhibiting a microscopic liquid phase and a macroscopic solid phase during operation. Straw is a porous material, with rice straw having an average porosity of 83.5%. It is an extremely inexpensive encapsulation material for phase change heat storage materials. However, the amount of straw directly affects the mechanical properties of the blocks (precast slabs); too little straw will severely impact insulation or heat storage performance. Using waste straw as the walls of solar greenhouses helps balance moisture and replenish carbon dioxide within the greenhouse, demonstrating excellent carbon reduction capabilities. This not only benefits ecological cycles and the development of green agriculture but also expands the utilization pathways of straw, resulting in significant economic and social benefits. Summary of the Invention

[0006] The technical problem to be solved by this invention is to provide a geopolymer straw phase change block and its preparation method, which addresses how to use the straw of major crops to prepare phase change blocks and improve the utilization rate of agricultural waste.

[0007] The technical solution of this invention to solve the above-mentioned technical problems is as follows: A geopolymer straw phase change block, comprising the following raw materials in parts by weight: 25%-35% straw powder shaped phase change heat storage material particles, 15%-25% fly ash shaped organic phase change heat storage material, 10%-20% fly ash, 10%-20% metakaolin, 10%-15% alkali activator, 0.1-1.0% coupling agent, 0.9%-2.5% polymer cementing material, and 9%-12% water;

[0008] The straw powder-shaped phase change heat storage material particles are obtained by the following method: 1) the straw powder is shaped into phase change heat storage material particles.

[0009] 1) The straw surface is alkali-liquefied and crushed to less than 2 mm to obtain straw powder; 2) The polymer adhesive and deionized water are stirred and dissolved to prepare adhesive solution A; 3) The first organic phase change heat storage material is heated to a molten state and mixed with silicon source material to prepare composite phase change liquid B; 4) Adhesive solution A and emulsifier are added to composite phase change liquid B solution so that composite phase change liquid B is suspended in adhesive solution A in the form of droplets to obtain dispersion C; 5) Straw powder and dispersion C are stirred and mixed evenly, a penetrant is added to make it fully impregnated and penetrated, a coagulant solution is added under temperature conditions, stirred evenly, dried, and crushed to obtain straw powder shaped phase change heat storage material; 6) The straw powder shaped phase change heat storage material is mixed with metakaolin, a coupling agent and water are added and stirred evenly, the mixture is granulated and dried to obtain straw powder shaped phase change heat storage material particles;

[0010] Fly ash-based shaped organic phase change thermal storage materials are obtained through the following methods: fly ash undergoes organic processing...

[0011] 1) Acid soaking, water washing, drying, and grinding and sieving; 2) Mix the treated fly ash and the second organic phase change heat storage material, heat until melted and stirred, cool and solidify into powder.

[0012] The beneficial effects of this invention are: This invention utilizes agricultural waste straw to produce a phase change wall suitable for solar greenhouses through a specific processing technology, which is not easy to leak and has stable sealing; When this phase change wall is applied to solar greenhouses, it can ensure that the indoor temperature is above 12.5°C even when the outdoor minimum temperature can reach below -33°C.

[0013] First, the surface of the straw is alkali-liquefied, taking into full account the crucial role of the entire system of preparing straw phase change blocks (precast slabs) using geopolymers in this invention under alkaline conditions. This is based on the fact that the free energy of the straw surface is approximately 25 mJ / m², and the inner surface is approximately 20 mJ / m². 2 Straw has a much lower surface activity than wood, resulting in lower bonding strength with cementitious materials. This is mainly due to the waxy and siliceous layers on its surface affecting the adhesive's bonding performance. Therefore, surface pretreatment is necessary. Alkali solution has a strong effect on removing lignin and reducing crystallinity. Alkali solution can effectively reduce the impact of sugars and other impregnating substances on the hardening of cementitious materials. Although straw treated with alkali solution still leaches sugars and other substances, when the straw content is appropriate, the tensile strength of the straw is greater than the effect of sugars on the hydration of the cementitious material. It can be seen from the above that straw surface treatment has a significant impact on the mechanical properties of straw cementitious (cement-based) composite materials.

[0014] Secondly, crushing the straw into powder below 2mm aims to increase its specific surface area and pore structure, thereby enabling...

[0015] Improve the adsorption performance of adsorbent materials; increase the contact area between straw and cementing materials to improve their cementing performance and strength.

[0016] Thirdly, the preparation of straw powder-based phase change thermal storage materials is one of the key aspects of this invention. To maintain the long-term stable operation of the straw phase change block (precast panel) wall and its associated solar greenhouse characteristics, the straw powder undergoes a shaping treatment and is then combined with the phase change material. This enhances the structural stability of the material, prevents leakage and loss of the phase change material during multiple phase change processes, and improves its service life and reliability. After alkali treatment of the straw powder, water molecules and the alkali, which can act as a catalyst, permeate through the polymer adhesive to the surface of the n-alkane phase of the phase change thermal storage material. The silicon source on the surface undergoes hydrolysis and condensation. Driven by the concentration difference, the silicon source inside the n-alkane phase of the phase change thermal storage material continuously migrates to the surface of the n-alkane phase, hydrolyzing and condensing to form a thin film. This film effectively prevents the leakage of the n-alkane phase of the phase change thermal storage material. The n-alkane phase change material in the straw powder is effectively encapsulated within the SiO2 film, achieving the effect of preventing leakage of the n-alkane phase change thermal storage material. This treatment method utilizes multiple chemical and physical principles, including alkali catalysis, solution permeation, and concentration gradient driving, making it a complex yet effective material processing approach. Specifically, the straw powder contains n-alkane phase change heat storage material and a polymer adhesive matrix. The straw powder is placed in an alkaline solution for treatment, with the alkali acting as a catalyst in the subsequent reaction process. Water molecules and the catalyst in the alkaline solution permeate into the fiber interior through the polymer adhesive matrix (the network structure of the adhesive), ultimately reaching the surface of the n-alkane phase of the phase change heat storage material. The carbon source material is a silane compound, which, under alkali catalysis, hydrolyzes to generate silicic acid (Si(OH)4), which then condenses to form a silicon dioxide (SiO2) film. The specific reaction is as follows: Hydrolysis reaction: Si(OC2H5)4 + 4H2O → Si(OH)4 + 4C2H5OH

[0017] Condensation reaction: Si(OH)4 → SiO2 + 2H2O

[0018] Because the carbon source concentration inside the n-alkane phase of the phase change thermal storage material is high, while hydrolysis and condensation reactions have already occurred on the surface, forming a low-concentration region, this concentration difference drives the carbon source inside the n-alkane phase to migrate to the surface. As the carbon source on the surface of the n-alkane phase of the phase change thermal storage material continues to hydrolyze and condense, a uniform SiO2 film gradually forms. This film acts as a seal, preventing leakage of the n-alkane phase from the phase change thermal storage material.

[0019] Fourth, the coupling agent reacts chemically with the active groups on the straw surface to form chemical bonds, binding the coupling agent to the straw surface. Interaction forces exist between the coupling agent molecules and the straw surface, such as van der Waals forces and electrostatic forces, causing the coupling agent to adsorb onto the straw surface. This effectively binds the straw to the inorganic materials in the cementitious material. This improves the strength and stability of the straw cementitious material, enabling it to withstand greater pressure and tension, and increasing its compressive and tensile strength. The coupling agent can increase the stability of the straw cementitious material, preventing cracking and detachment during use, and extending its service life.

[0020] Fifth, penetrants are used to improve the permeability of straw powder. By altering the surface tension and permeability of the straw powder, they allow phase change liquids to more easily penetrate into the cellular structure of the straw. The purpose of penetrants is to enhance the permeability of straw powder, making it easier for it to absorb and retain phase change liquids. This is crucial for processes such as straw preservation, waterproofing, and fireproofing. Penetrants allow the phase change liquid to penetrate more evenly into all parts of the straw powder, improving treatment effectiveness and efficiency. Furthermore, penetrants can improve the physical properties of straw powder, such as increasing its hardness, abrasion resistance, and weather resistance, thereby extending its service life.

[0021] In summary, this invention involves granulating straw powder and metakaolin cementitious material to adsorb saturated phase change thermal storage materials. The cementitious material undergoes a hydration reaction in the presence of water, forming a gelling substance that creates bonding forces between particles. This further increases the stability of the straw powder-based phase change thermal storage material and effectively prevents leakage. It also increases the surface area and thermal conductivity of the straw powder-based phase change thermal storage material. Granulating the straw powder and cementitious material increases the specific surface area and pore structure of the adsorbent material, enhancing its adsorption capacity for phase change materials and thus increasing the thermal storage performance. Furthermore, granulating the straw powder and cementitious material to adsorb saturated phase change thermal storage materials creates a uniform granular structure, facilitating the storage of the phase change material. Simultaneously, the mixing and granulation of the straw powder and cementitious material utilizes the binding effect of the cementitious material to bond the straw powder particles together, forming a robust granular structure. The cementitious material undergoes a hydration reaction in the presence of water, forming a gelling substance that creates bonding forces between particles.

[0022] Based on the above technical solution, the present invention can be further improved as follows.

[0023] Furthermore, the alkali used in the alkali liquefaction treatment is any one of sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium silicate, sodium carbonate, and sodium bicarbonate. The mass ratio of straw to alkali is 1:1 to 1:3, the soaking time is more than 24 hours, and the temperature is 60-80℃.

[0024] Furthermore, the polymeric adhesive is any one of polyvinyl alcohol (PVA), urea-formaldehyde resin, xanthan gum, guar gum, soybean protein gum, polyvinyl acetate, and VAE; the adhesive solution A has a mass percentage of 8-12%, and the stirring and dissolving temperature is 75-85℃ for more than 2 hours.

[0025] There is a physical adsorption relationship between the molecules in the polymer adhesive and the molecules on the surface of the straw particle-metakaolin-fly ash polymer. Through intermolecular forces, a certain degree of adhesion is formed between the adhesive and the straw particle-metakaolin-fly ash polymer. The molecules in the polymer adhesive can also chemically react with the molecules on the surface of the straw particle-metakaolin-fly ash polymer to form chemical bonds, thus achieving adhesion. The polymer adhesive can penetrate into the microporous structure of the straw particle-metakaolin-fly ash polymer, filling the pore spaces and increasing the contact area, thereby enhancing the bonding effect. The polymer adhesive can improve the strength of the straw particle-metakaolin-fly ash polymer blocks, making them more robust and durable. The polymer adhesive can fill the gaps between the straw stalks, increasing the cohesion of the blocks, thereby improving their compressive and flexural strength. The polymer adhesive can also improve the fire resistance of the straw particle-metakaolin-fly ash polymer blocks. Polymer adhesives can form a flame-retardant layer, slowing the spread of fire and improving the fire resistance of blocks.

[0026] Furthermore, the silicon source material used is any one of TEOS (tetraethoxysilane), TMOS (methyltriethoxysilane), MTMS (methyltrimethoxysilane), methylsilane (MTES), ethylsilane (ETES), or phenylsilane (PhTES); the first organic phase change heat storage material is heated to a molten state with a mass ratio of 9:1 to the silicon source material; adhesive solution A is added to the composite phase change liquid B solution, with a mass ratio of 1:1.5 between the composite phase change liquid B solution and the adhesive solution A, and the emulsifier is 5% of the total mass of the composite phase change liquid B solution and the adhesive solution A.

[0027] Furthermore, the emulsifier is any one of Tween80, Tween40, Tween20, OP-10, K12, E-1300, and MES.

[0028] Furthermore, the straw powder and dispersion C are mixed evenly at a mass ratio of 1:1 to 1:3, and a penetrant of 0.1-0.5% of the total mass of the straw powder and dispersion C is added; the coagulant is 10% of the total mass of the straw powder and dispersion C.

[0029] Furthermore, the penetrant is any one of sodium di-2-octyl maleate sulfonate, BX splitting powder, naphthalene sulfonate NNO, fatty alcohol polyoxyethylene ethers, ammonium lignin sulfonate, ethylene glycol butyl ether, and dimethyl sulfoxide; the coagulant is any one of Na2SO4·10H2O, Na2SiO3·9H2O, K2SO4·5H2O, K2SiO3·2H2O, MgSO4·7H2O, ZnSO4·7H2O, and CaCl2·6H2O.

[0030] The selection of the penetrant in this invention fully considers its compatibility with polymer cementitious materials. The main effects of this type of substance on cementitious materials include improved workability, enhanced freeze-thaw resistance, increased impermeability, and improved resistance to carbonation and chloride ion penetration. It enhances the early and later strength of concrete, improves concrete workability, reduces cement usage, increases fluidity, saves cement, and its dispersibility and low surface tension improve the adhesion and water resistance of the material.

[0031] Furthermore, the straw powder shaped phase change heat storage material and metakaolin are mixed at a mass ratio of 1:1 to 1:3, and the coupling agent used is 1% to 5% of the mass of the straw powder; the coupling agent is any one of KH-550, KH-560, KH-570, KR-55, Lica-38, 1-amino-2-naphthalenesulfonic acid, and 4-amino-1-naphthalenesulfonic acid;

[0032] Furthermore, the amount of organic acid used in the organic acid soaking is 4% of the fly ash mass, with water added in a 1:1 ratio to the fly ash, stirred at 50-70℃ for 2-3 hours, preferably 60℃, and passed through an 80-120 mesh sieve, preferably a 100 mesh sieve; the organic acid is any one of oxalic acid, phytic acid, citric acid, salicylic acid, malic acid, tannic acid, and tartaric acid; the second organic phase change heat storage material is n-alkanes (C n H 2n+2 Any one or two of them.

[0033] Organic acid soaking is used to increase the adsorption and dispersibility of fly ash and modify its surface structure. Modified fly ash has a stronger adsorption capacity than unmodified fly ash. However, using strong acids or alkalis to modify fly ash can easily damage its structure. This invention uses weak acids to modify fly ash, which has advantages such as short modification time, fast speed, high efficiency, and mild modification conditions. The adsorption capacity of fly ash modified with organic acids is significantly increased compared to unmodified fly ash. After modification, the specific surface area of ​​fly ash can be increased, improving its adsorption and dispersibility.

[0034] Furthermore, the alkaline activator is any one or more of sodium silicate, potassium silicate, lithium silicate, aluminum silicate, sodium hydroxide, potassium hydroxide, calcium hydroxide, and sodium carbonate; the polymer cementing material is any one of urea-formaldehyde resin, isocyanate resin, phenolic resin, melamine-formaldehyde resin, acrylic resin, and VAE resin.

[0035] Considering the addition of a certain amount of alkaline activator during the preparation of straw particles and metakaolin-fly ash polymers, the reaction system is alkaline. Some pectin and lignin on the surface of straw will dissolve, increasing the surface roughness. The mechanical interlocking between straw particles and metakaolin-fly ash polymers at the interface, as well as the adhesion caused by adsorption and wetting, will also be enhanced.

[0036] This invention also provides a method for preparing geopolymer straw phase change blocks, wherein an alkali activator and an alkali saturated solution are introduced into a stirred tank at a ratio of 4:1 to 2:1 to prepare activator solutions with different moduli, cooled to room temperature, stirred, and then subjected to ultrasonic vibration to obtain an alkali activator solution; the alkali in the alkali saturated solution can be any one of sodium carbonate, potassium hydroxide, calcium hydroxide, potassium hydroxide, and potassium silicate.

[0037] The block molding process of this invention involves mixing and stirring straw powder-shaped phase change heat storage material particles, fly ash-shaped organic phase change heat storage material, fly ash, metakaolin, the alkali activator solution, and deionized water in a disperser. Then, coupling agent and polymer cementitious material are added sequentially. The uniformly mixed slurry is poured into a mold, vibrated and cured, and demolded to obtain geopolymer straw phase change blocks. The uniformly mixed slurry is poured into a mold and vibrated for 1 minute using YLT5-20 type concrete at 20°C and relative humidity greater than 90%.

[0038] Extensive application tests revealed weak adhesion between straw particles and the metakaolin-fly ash geopolymer matrix, with gaps and cracks appearing at the interface. No new chemical bonds were formed between them, and no chemical bonding occurred between the straw particles and the geopolymer. After straw incorporation, a weak physical bond was formed between the straw particles and the metakaolin-fly ash geopolymer, resulting in a loose interface structure and decreased compressive strength. Improved thermal insulation performance is achieved by modifying the surface of straw, as sugars and lignin in straw form an adsorption layer on the cement surface, affecting the cement hydration process and reducing the hydration rate. Adding coupling agents improves the mechanical properties of the geopolymer. Through hydrolysis, the coupling agent acts as a bridge between the geopolymer and the polymer binder, forming Si-O-Si bonds with the geopolymer and covalent bonds with the polymer binder. This improves the plasticity and hydrophobicity of the straw particle-metakaolin-fly ash geopolymer, thereby enhancing the crack resistance and water resistance of the coating and preventing cracking caused by volume shrinkage. During the preparation of geopolymer blocks, the main product is amorphous aluminosilicates. The coupling agent chemically bonds with the geopolymer to form clusters that fill the pores of the geopolymer. The density of the straw particle-meta-kaolin-fly ash aggregate was increased, and the hardness of the straw particle-meta-kaolin-fly ash aggregate was also increased accordingly.

[0039] Extensive application tests have revealed that when straw-based materials are mixed with polymer cementitious materials as composite building materials, the addition of large amounts of straw is problematic. This results in insufficient adsorption as a carrier for the phase change heat storage material, significantly impacting the heat storage capacity of straw phase change blocks (precast slabs). Straw-based materials typically have low thermal conductivity, providing good insulation. However, limiting straw addition can decrease insulation performance, leading to poor insulation results. Traditional straw cement or straw concrete cannot be widely used due to the increased cost associated with the limited addition of straw. Furthermore, the inability to add large amounts of straw reduces the overall strength of the composite material, affecting the structural safety of straw phase change blocks (precast slabs). Excessive addition, on the other hand, reduces the durability of the composite material, impacting the service life of the straw phase change blocks (precast slabs). This invention incorporates straw into geopolymers, leveraging the geopolymer's inherent advantages of high strength, rapid curing, good durability, corrosion resistance, and high temperature resistance. This allows for the addition of large amounts of straw (compared to 5% for traditional masonry blocks, this invention's straw particle-meta-kaolin-fly ash geopolymer can reach 30%) to prepare a novel heat-storing and insulating building material.

[0040] A novel geopolymer thermal insulation building material can be prepared by mixing phase change thermal storage materials, fly ash, metakaolin, and straw. This material exhibits excellent thermal storage and insulation performance as well as mechanical strength, effectively reducing building energy consumption. Furthermore, the addition of fly ash and metakaolin provides good fire resistance. The material also demonstrates good high-temperature resistance; its structural stability and mechanical properties remain largely unchanged under high-temperature conditions, without significant deformation or damage. This makes it a promising candidate for applications in high-temperature environments, particularly for insulation and heat insulation of high-temperature industrial equipment.

[0041] During the calcination process of ordinary silicate cement raw materials, the formation and release of CO2 significantly increases carbon emissions; the production of 1 kg of ordinary silicate cement can generate 0.66-0.82 kg of carbon emissions. With the emergence of the concept of "green building materials," more and more scholars have begun to focus on geopolymers. These require no batching or calcination processes and can be prepared simply by activating some industrial waste with alkali. Compared to cement, production energy consumption is reduced by 70%, and total pollution is reduced by 90%. Comparing greenhouse gas emissions from fly ash-based geopolymers and ordinary concrete, the carbon dioxide emissions per cubic meter of ordinary concrete are 321.5 kg, while those per cubic meter of fly ash-based geopolymer concrete are 273.3 kg, a reduction of approximately 15%. Straw particle-metakaolin-fly ash geopolymers reduce carbon dioxide emissions by more than 70%.

[0042] This invention integrates the traditional use of crop straw with the vast amount of industrial waste fly ash, providing a new and excellent approach for the resource-based reuse of fly ash and straw, and also offering new ideas for the thermal insulation properties of building materials.

[0043] This invention also provides a straw phase change block wall and its associated solar greenhouse (Tongliao area, Inner Mongolia).

[0044] The parameters for designing a solar greenhouse can be positively correlated with the latitude, temperature, and solar altitude angle at the winter solstice of the greenhouse's location, and can be obtained based on a large number of statistical equations: Optimal front roof angle: α = θ + φ - 40º + γ, where θ is the latitude of the solar greenhouse's location; φ is the latitude of the equator; and γ represents the value by which the solar altitude angle at 9:00 and 16:00 on the winter solstice is lower than that at noon by 0º-4º.

[0045] The optimal rear canopy tilt angle β = ω + 0.5 * (ω s -ω)* η, where ω is the local solar altitude angle at the winter solstice, ω s The solar altitude angle at the vernal equinox is η = 1.15, which is a constant coefficient.

[0046] The mathematical equations for span L, rear wall height h, and total height H are: H = L * = (L1 + L2) * h=H- L2* .

[0047] According to the statistical data, the length of the rear roof (M) is 2.0m for the two specifications with spans L of 10m and 12m; 2.4m for the span of L=14m; and 3.6m for the span of 16m. The horizontal projection length of the rear roof is L2=M×cosβ.

[0048] Wall thickness δ w A mathematical model and equations were established based on the thermal inertia index (D value) and building thermal calculations: In accordance with the requirements of the "Standard for Energy Conservation Design of Public Buildings" (GB 50189—2015), in the building envelope, the external wall...

[0049] (1) Overall heat transfer coefficient K0 ≤ 1.5 W / (m 2 .K), the optimal value K0≤1.0w / (m 2 .K); (2) K0=1 / R 总 =1 / (R i +∑R λ +Re), where K0 is the overall heat transfer coefficient w / (m²). 2 .K);R i The thermal transfer resistance of the inner surface of the wall is taken as 0.115 m. 2 .K / w; Re is the thermal transfer resistance of the outer surface of the wall, taken as 0.0443 m. 2 .K / w.

[0050] (3) ∑R λ =∑δ / λ, R_total = R i +∑R λ +Re, ∑δ represents the thickness of each component layer (structural layer) of the greenhouse wall.

[0051] (4) Thermal inertia index (D value): For single-layer structures, D = R•S; for multi-layer structures, D = ∑R•S. Where R is the thermal resistance of the structural layer and S is the heat storage coefficient of the corresponding material layer.

[0052] The outer walls of the greenhouse, which are made of 400-600 mm thick phase change foamed concrete blocks / precast panels, are equipped with 100-150 mm thick extruded polystyrene insulation boards. The greenhouse consists of an indoor floor, a 100-150 mm thick extruded polystyrene insulation board wall to the local frost line, a low wall on the sunny side, and a roof panel. Attached Figure Description

[0053] Figure 1 This is a schematic diagram of the structure of the solar greenhouse of the present invention.

[0054] The attached diagram lists the components represented by each number as follows:

[0055] 1. Nano-thermal conductive coating layer; 2. Phase change heat storage material layer; 3. Phase change foamed concrete precast block / panel wall; 4. Extruded polystyrene board exterior wall insulation layer; 5. Exterior wall coating layer; 6. Greenhouse rear wall foundation; 7. Underground rear extruded polystyrene insulation board; 8. Greenhouse rear roof; 9. Cotton quilt; 10. Winch; 11. Greenhouse front roof; 12. Greenhouse front opening foundation; 13. Underground front extruded polystyrene insulation board. Detailed Implementation

[0056] The principles and features of the present invention are described below with reference to the accompanying drawings. The embodiments described are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0057] Example 1

[0058] Preparation of straw powder-based phase change thermal storage material particles: Wheat straw was coarsely crushed into 2 cm lengths using a jaw crusher. The straw was soaked in a solution of 330 parts by weight of the coarsely crushed straw and 670 parts by weight of saturated sodium hydroxide for 24 hours, with the temperature controlled at 70℃. It was then rinsed with clean water and dried. Finally, it was finely crushed using an ultrafine grinding mill or similar equipment to obtain straw powder of 1 mm.

[0059] Preparation of straw powder-based phase change thermal storage material: First, 100 parts by mass of urea-formaldehyde resin and 900 parts by mass of deionized water were dissolved by stirring at 80℃ for 2 hours to obtain a 10% urea-formaldehyde resin solution A. Next, 900 parts by mass of n-trisane were heated to a molten state and mixed with 100 parts by mass of silicon source material TMOS (methyltriethoxysilane) to prepare a composite phase change liquid B. Then, 400 parts by mass of solution B were added to 600 parts by mass of urea-formaldehyde resin solution, along with 50 parts by mass of OP-10, so that the composite phase change liquid B was suspended in the urea-formaldehyde resin solution A in the form of small droplets to obtain a dispersion C. 495 parts by weight of straw powder were impregnated in 500 parts by weight of dispersion C. 5 parts by weight of BX powder were added to fully impregnate and penetrate the powder. Under the condition of maintaining the temperature, 100 parts by weight of Na2SiO3·9H2O were added and stirred evenly. The pH was adjusted to 12 and maintained at 60℃ for 4 hours. After further drying and pulverization, straw powder-shaped n-trisane phase change heat storage material was obtained.

[0060] Granulation of metakaolin and straw powder-shaped phase change thermal storage material: 800 parts by weight of straw powder-shaped n-trisane phase change thermal storage material and metakaolin are mixed evenly. 200 parts by weight of water are added and stirred. 10 kg of coupling agent KH550 is added and stirred evenly. The mixture is then removed and granulated using a granulator or tablet press. The granulated particles are then naturally air-dried or oven-dried. This yields metakaolin and straw powder-shaped n-trisane phase change thermal storage material particles.

[0061] Preparation of modified organic phase change thermal storage material from fly ash: 40 parts by weight of tannic acid were added to 480 parts by weight of water and stirred evenly. Then, 480 parts by weight of fly ash were added and stirred evenly at high speed. After stirring at 60°C for 2 hours, the mixture was filtered, washed with water, dried, ground, and passed through a 100-mesh sieve to obtain modified fly ash.

[0062] Preparation of fly ash-shaped organic phase change heat storage material: 550 parts by mass of n-tridecane were heated to 50°C and completely melted. After stirring evenly, 450 parts by mass of fly ash were added. After stirring for 30 minutes, the mixture was allowed to cool naturally until solidification, ensuring that the fly ash fully absorbed the phase change material. After cooling, the surface of the mixture was observed. If crystals appeared, the mixture was in a supersaturated state, and the fly ash-shaped n-tridecane phase change heat storage material was obtained.

[0063] Preparation of geopolymer straw phase change blocks (precast slabs): 80 parts by weight of sodium silicate were added to 40 parts by weight of saturated sodium carbonate solution. The mixture was then poured into a stirring vessel and stirred until the activator solution was homogeneous. After cooling to room temperature, the mixture was stirred and then placed in an ultrasonic cleaner and vibrated for 5 minutes to make the alkali activator clear and transparent. After standing for 24 hours, it was ready for use. 200 parts by weight of metakaolin, 350 parts by weight of straw powder tridecane phase change heat storage material particles, 200 parts by weight of fly ash shaped n-tridecane phase change heat storage material, 140 parts by weight of fly ash, and 90 parts by weight of deionized water were mixed and stirred in a disperser at 1200 r / min for 30 min. Then, 10 parts by weight of KH550 and 10 parts by weight of urea-formaldehyde resin were added, and the mixture was stirred at 1200 r / min for 15 min. The homogeneous slurry was poured into a mold, and the insulation bricks were formed by vibration. The YLT5-20 type concrete used in the vibration molding process is vibrated for 1 minute and cured at 20℃ and relative humidity greater than 90% until it has sufficient strength. The resulting geopolymer straw phase change blocks (precast slabs) are then demolded.

[0064] Example 2

[0065] Preparation of straw powder-based phase change heat storage material particles: Rice was coarsely crushed into 2 cm lengths using a jaw crusher. The straw was soaked in a solution of 500 parts by weight of coarsely crushed straw and 500 parts by weight of saturated sodium silicate for 24 hours at a controlled temperature of 70℃. It was then rinsed with clean water and dried. Finally, it was finely crushed using an ultrafine grinding mill or similar equipment to obtain straw powder of 1 mm.

[0066] Preparation of straw powder-based phase change thermal storage material: First, 100 parts by mass of PVA resin and 900 parts by mass of deionized water were dissolved by stirring at 80℃ for 2 hours to obtain a 10% PVA solution A. Next, 900 parts by mass of n-docosahexanes were heated to a molten state and mixed with 100 parts by mass of the silicon source material TEOS (tetraethoxysilane) to prepare a composite phase change liquid B. Then, 1000 parts by mass of solution B were added to 1500 parts by mass of the PVA resin solution, along with 125 parts by mass of Tween 80, so that the composite phase change liquid B was suspended in the adhesive solution A in the form of small droplets to obtain a dispersion C. 497 parts by weight of straw powder were impregnated in 500 parts by weight of dispersion C. 3 parts by weight of fatty alcohol polyoxyethylene ether were added for thorough impregnation. While maintaining the temperature, 100 parts by weight of Na2SO4·10H2O were added and stirred until homogeneous. The pH was adjusted to 12 and maintained at 60℃ for 4 hours. After further drying and pulverization, straw powder-shaped n-tetradecane phase change heat storage material was obtained.

[0067] Granulation of metakaolin and straw powder shaped phase change heat storage material: First, mix 270 parts by weight of straw powder shaped n-docosahexadecane phase change heat storage material and 540 parts by weight of metakaolin evenly, add 150 parts by weight of water and stir, add 40 kg of coupling agent KH-570 and stir evenly, take out the mixture and granulate it through a granulator or tablet press, and let the granulated particles air dry or dry to obtain straw powder shaped n-docosahexadecane phase change heat storage material particles.

[0068] Preparation of modified organic phase change thermal storage material from fly ash: 40 parts by weight of oxalic acid were added to 480 parts by weight of water and stirred evenly. Then, 480 parts by weight of fly ash were added and stirred evenly at high speed. After stirring at 60°C for 2 hours, the mixture was filtered, washed with water, dried, ground, and passed through a 100-mesh sieve to obtain modified fly ash.

[0069] Preparation of fly ash-shaped organic phase change heat storage material: 600 parts by mass of n-docosahexanes were heated to 45°C and completely melted. After stirring evenly, 400 parts by mass of fly ash were added. After stirring for 30 minutes, the mixture was allowed to cool naturally until solidification, ensuring that the fly ash fully absorbed the phase change material. After cooling, the surface of the mixture was observed. If crystals appeared, the mixture was in a supersaturated state, and the fly ash-shaped n-docosahexanes phase change heat storage material was obtained.

[0070] Preparation of geopolymer straw phase change blocks (precast slabs): 90 parts by weight of lithium silicate were added to 60 parts by weight of saturated potassium hydroxide solution. The mixture was then poured into a stirring vessel and stirred until the activator solution was homogenized. After cooling to room temperature, the mixture was stirred again and then placed in an ultrasonic cleaner and vibrated for 5 minutes to make the alkali activator clear and transparent. The mixture was then allowed to stand for 24 hours before use. 100 parts by weight of metakaolin, 319 parts by weight of straw powder-shaped n-docosahexadecane phase change heat storage material particles, 250 parts by weight of fly ash-shaped n-docosahexadecane phase change heat storage material, 200 parts by weight of fly ash, and 120 parts by weight of deionized water were mixed and stirred in a disperser at 1200 r / min for 30 min. Then, 1 part by weight of KH570 and 10 parts by weight of VAE emulsion were added, and the mixture was stirred again at 1200 r / min for 15 min. The homogenized slurry was poured into molds, and the insulation bricks were formed using vibration molding. The YLT5-20 type concrete used in the vibration molding process was vibrated for 1 minute and cured at 20℃ and relative humidity greater than 90% until it had sufficient strength. The resulting geopolymer straw phase change blocks (precast slabs) were then demolded.

[0071] Example 3

[0072] Preparation of straw powder-based phase change thermal storage material particles: straw ultrafine processing and alkaline surface treatment

[0073] Corn stalks were coarsely crushed into 2cm lengths using a jaw crusher. They were then soaked in a solution of 250 parts by weight of the coarsely crushed stalks and 750 parts by weight of a saturated sodium hydroxide solution for 24 hours, maintaining a temperature of 70℃. After soaking, the stalks were rinsed with clean water and dried. Finally, they were finely crushed using an ultrafine grinding mill or similar equipment to produce 0.5mm stalk powder.

[0074] Preparation of straw powder-based phase change thermal storage material: First, 100 parts by mass of VAE resin and 900 parts by mass of deionized water were dissolved by stirring at 80℃ for 2 hours to obtain a 10% VAE solution A. Next, 900 parts by mass of n-nonadecane were heated to a molten state and mixed with 100 parts by mass of MTMS (methyltrimethoxysilane) to prepare a composite phase change liquid B. Then, 500 parts by mass of solution B were added to 750 parts by mass of VAE resin solution, along with 62.5 parts by mass of Tween 20, so that the composite phase change liquid B was suspended in the VAE resin solution A as small droplets to obtain a dispersion C. 496 parts by weight of straw powder were impregnated in 500 parts by weight of dispersion C. 4 parts by weight of sodium di-2-octyl maleate sulfonate were added for thorough impregnation. Under the condition of maintaining the temperature, 100 parts by weight of Zn2SO4·7H2O were added and stirred evenly. The pH was adjusted to 12 and maintained at 60℃ for 4 hours. After further drying and pulverization, straw powder-shaped n-nonadecane phase change heat storage material was obtained.

[0075] Granulation of metakaolin and straw powder-shaped phase change thermal storage material: First, mix 400 parts by weight of straw powder-shaped n-nonadecane phase change thermal storage material and 400 parts by weight of metakaolin until homogeneous. Add 180 parts by weight of water and stir. Add 20 parts by weight of KH-550 and stir until homogeneous. Remove the mixture and granulate it using a granulator or tablet press. Allow the granulated particles to air dry or bake. This yields straw powder-shaped n-nonadecane phase change thermal storage material particles.

[0076] Modification of fly ash: Add 20 parts by weight of citric acid to 240 parts by weight of water and stir evenly. Add 240 parts by weight of fly ash and stir evenly at high speed. After stirring at 60°C for 2 hours, filter, wash with water, dry, grind, and pass through a 100-mesh sieve to obtain modified fly ash.

[0077] Preparation of fly ash-shaped organic phase change heat storage material: 500 parts by mass of n-nonadecane were heated to 35°C and completely melted. After stirring evenly, 500 parts by mass of fly ash were added and stirred for 30 minutes. The mixture was then allowed to cool naturally until solidification, ensuring that the fly ash fully absorbed the phase change material. After cooling, the surface of the mixture was observed. If crystals appeared, the mixture was in a supersaturated state, thus obtaining the fly ash-shaped n-nonadecane phase change heat storage material.

[0078] 3. Preparation of Geopolymer Straw Phase Change Blocks (Precast Slabs): According to the mass ratio, straw powder is used for shaping phase change heat storage.

[0079] Preparation of geopolymer straw phase change blocks (precast slabs): 80 parts by weight of potassium silicate were added to 20 parts by weight of saturated calcium hydroxide solution. The mixture was then poured into a stirring vessel and stirred until the activator solution was homogeneous. After cooling to room temperature, the mixture was stirred and then placed in an ultrasonic cleaner and vibrated for 5 minutes to make the alkali activator clear and transparent. After standing for 24 hours, it was ready for use. 200 parts by weight of metakaolin, 250 parts by weight of straw powder-shaped n-nonadecane phase change heat storage material particles, 200 parts by weight of fly ash-shaped n-nonadecane phase change heat storage material, 200 parts by weight of fly ash, and 120 parts by weight of deionized water were mixed and stirred in a disperser at 1200 r / min for 30 min. Then, 5 parts by weight of KH-550 coupling agent and 25 parts by weight of isocyanate resin were added, and the mixture was stirred again at 1200 r / min for 15 min. The homogeneous slurry was poured into a mold, and the insulation bricks were formed by vibration. The YLT5-20 type concrete used in the vibration molding process was vibrated for 1 minute and cured at 20℃ and relative humidity greater than 90% until it had sufficient strength. The resulting geopolymer straw phase change blocks (precast slabs) were then demolded.

[0080] Example 4

[0081] Preparation of straw powder-based phase change thermal storage material particles: straw ultrafine processing and alkaline surface treatment

[0082] Soybean straw was coarsely crushed into 2cm lengths using a jaw crusher. It was then soaked in a saturated sodium hydroxide solution (670 parts by weight) for 24 hours at 70℃, with the coarsely crushed straw mixed with 330 parts by weight of the solution. After soaking, the straw was rinsed with clean water and dried. Finally, it was finely crushed using an ultrafine grinding mill or similar equipment to produce straw powder of 1.5mm.

[0083] Preparation of straw powder-based phase change thermal storage material: First, 100 parts by mass of soybean protein gum and 900 parts by mass of deionized oil were dissolved by stirring at 80℃ for 2 hours to obtain a 10% soybean protein gum solution A. Next, 900 parts by mass of n-dodecane were heated to a molten state and mixed with 100 parts by mass of ethoxysilane (ETES) to prepare a composite phase change liquid B. Then, 600 parts by mass of solution B were added to the 900 parts by mass of soybean protein gum solution, along with 75 parts by mass of Tween40, so that the composite phase change liquid B was suspended in the soybean protein gum solution A in the form of small droplets to obtain a dispersion C. 400 parts by weight of straw powder were impregnated in 600 parts by weight of dispersion C. 5 parts by weight of dimethyl sulfoxide were added for thorough impregnation. Under the condition of maintaining the temperature, 100 parts by weight of K2SO4·5H2O were added and stirred evenly. The pH was adjusted to 12 and maintained at 60℃ for 4 hours. After further drying and pulverization, straw powder-shaped docosane phase change heat storage material was obtained.

[0084] Granulation of metakaolin and straw powder shaped phase change thermal storage material: 280 parts by weight of straw powder shaped docosane phase change thermal storage material and 570 parts by weight of metakaolin are mixed evenly. 190 parts by weight of water are added and stirred. 10 parts by weight of Lica-38 are added and stirred evenly. The mixture is then removed and granulated using a granulator or tablet press. The granulated particles are then naturally air-dried or oven-dried to obtain straw powder shaped docosane phase change thermal storage material particles.

[0085] Modification of fly ash: Add 40 parts by weight of phytic acid to 480 parts by weight of water and stir evenly. Add 480 parts by weight of fly ash and stir evenly at high speed. After stirring at 60℃ for 2 hours, filter, wash with water, dry, grind, and pass through a 100-mesh sieve to obtain modified fly ash.

[0086] Preparation of fly ash-shaped organic phase change heat storage material: 670 parts by mass of n-dosane were heated to 45°C and completely melted. After stirring evenly, 330 parts by mass of fly ash were added. After stirring for 30 minutes, the mixture was allowed to cool naturally until solidification, ensuring that the fly ash fully absorbed the phase change material. After cooling, the surface of the mixture was observed. If crystals appeared, the mixture was in a supersaturated state, thus obtaining the fly ash-shaped n-dosane phase change heat storage material.

[0087] The preparation of geopolymer straw phase change blocks (precast slabs) is carried out according to the mass ratio of straw powder to form a phase change heat storage material.

[0088] Preparation of geopolymer straw phase change blocks (precast slabs): 67 parts by mass of aluminum silicate were added to 34 parts by mass of saturated sodium carbonate solution, and the mixture was stirred evenly in a mixing tank. After cooling to room temperature, the mixture was stirred and then placed in an ultrasonic cleaner and vibrated for 5 minutes to make the alkali activator clear and transparent. After standing for 24 hours, it was ready for use. 190 parts by mass of metakaolin, 250 parts by mass of straw powder-shaped docosane phase change heat storage material particles, 200 parts by mass of n-docosane phase change heat storage material, 130 parts by mass of fly ash, and 100 parts by mass of deionized water were mixed and stirred in a disperser at 1200 r / min for 30 min. Then, 5 parts by mass of Lica-38 and 25 parts by mass of acrylic resin were added, and the mixture was stirred at 1200 r / min for another 15 min. The evenly mixed slurry was poured into a mold, and the insulation bricks were formed by vibration. The YLT5-20 type concrete used in the vibration molding process is vibrated for 1 minute and cured at 20℃ and relative humidity greater than 90% until it has sufficient strength. The resulting geopolymer straw phase change blocks (precast slabs) are then demolded.

[0089] Example 5

[0090] Preparation of straw powder-based phase change thermal storage material particles: straw ultrafine processing and alkaline surface treatment

[0091] Sorghum stalks were coarsely crushed into 2cm lengths using a jaw crusher. They were then soaked in a solution of 450 parts by weight of coarsely crushed stalks and 550 parts by weight of saturated sodium hydroxide for 24 hours at 70℃. After rinsing with clean water, the sorghum stalks were air-dried. Finally, they were finely crushed using an ultrafine grinding mill or similar equipment to produce 1.5mm stalk powder.

[0092] Preparation of straw powder-based phase change thermal storage material: First, 100 parts by mass of guar gum and 900 parts by mass of deionized oil were stirred at 80℃ for 2 hours to dissolve and obtain a 10% guar gum solution A; then, 900 parts by mass of n-tetracosane were heated to a molten state and mixed with 100 parts by mass of methylsilane (MTES) to prepare a composite phase change liquid B; then, 300 parts by mass of solution B were added to 450 parts by mass of xanthan gum solution, and 37.5 parts by mass of MES were added at the same time, so that the composite phase change liquid B was suspended in the guar gum solution A in the form of small droplets to obtain a dispersion C. 330 parts by weight of straw powder were impregnated in 670 parts by weight of dispersion C. 3 parts by weight of naphthalene sulfonate NNO were added for thorough impregnation. Under the condition of maintaining the temperature, 100 parts by weight of K2SiO3·2H2O were added and stirred evenly. The pH was adjusted to 12 and maintained at 60℃ for 4 hours. After further drying and pulverization, straw powder-shaped n-tetracosane phase change heat storage material was obtained.

[0093] Granulation of metakaolin and straw powder-shaped phase change thermal storage material: 400 parts by weight of straw powder-shaped n-tetracosane phase change thermal storage material and 400 parts by weight of metakaolin are mixed evenly. 150 parts by weight of water are added and stirred. 50 parts by weight of 1-amino-2-naphthalenesulfonic acid are added and stirred evenly. The mixture is then removed and granulated using a granulator or tablet press. The granulated particles are then naturally air-dried or oven-dried to obtain straw powder-shaped n-tetracosane phase change thermal storage material particles.

[0094] Modification of fly ash: 20 parts by weight of malic acid were added to 240 parts by weight of water and stirred evenly. Then, 240 parts by weight of fly ash were added and stirred evenly at high speed. After stirring at 60°C for 2 hours, the mixture was filtered, washed with water, dried, ground, and passed through a 100-mesh sieve to obtain modified fly ash.

[0095] Preparation of fly ash-shaped organic phase change heat storage material: 750 parts by weight of n-tetracosane were heated to 55°C and completely melted. After stirring evenly, 250 parts by weight of fly ash were added. After stirring for 30 minutes, the mixture was allowed to cool naturally until solidification, ensuring that the fly ash fully absorbed the phase change material. After cooling, the surface of the mixture was observed. If crystals appeared, the mixture was in a supersaturated state, and the fly ash-shaped n-tetracosane phase change heat storage material was obtained.

[0096] 3. Preparation of geopolymer straw phase change blocks (precast slabs): According to the mass ratio, straw powder is used to shape phase change heat storage materials.

[0097] Preparation of geopolymer straw phase change blocks (precast slabs): 75 parts by mass of potassium silicate were added to 25 parts by mass of saturated potassium hydroxide solution, and the mixture was poured into a stirring vessel and stirred until the activator solution was homogeneous. After cooling to room temperature, the mixture was stirred again and then placed in an ultrasonic cleaner and vibrated for 5 minutes to obtain an alkali activator solution. 180 parts by mass of metakaolin, 250 parts by mass of straw powder-shaped n-tetracosane phase change heat storage material particles, 150 parts by mass of fly ash-shaped n-tetracosane phase change heat storage material, 150 parts by mass of fly ash, 150 parts by mass of alkali activator, and 100 parts by mass of deionized water were mixed and stirred in a disperser at 1200 r / min for 30 min. Then, 3 parts by mass of 1-amino-2-naphthalenesulfonic acid and 17 parts by mass of phenolic resin were added, and the mixture was stirred again at 1200 r / min for 15 min. The homogeneous slurry was poured into a mold, and the insulation bricks were formed by vibration. The YLT5-20 type concrete used in the vibration molding process was vibrated for 1 minute and cured at 20℃ and relative humidity greater than 90% until it had sufficient strength. The resulting geopolymer straw phase change blocks (precast slabs) were then demolded.

[0098] Example 6

[0099] Preparation of straw powder-based phase change thermal storage material particles: straw ultrafine processing and alkaline surface treatment

[0100] Sugarcane stalks were coarsely crushed into 2cm lengths using a jaw crusher. 470 parts by weight of the stalk powder were soaked in a saturated sodium bicarbonate solution (530 parts by weight) for 24 hours at 70℃. The mixture was then rinsed with clean water and dried. Finally, it was finely crushed using an ultrafine grinding mill or similar equipment to produce 1.5mm stalk powder.

[0101] Preparation of straw powder-based phase change thermal storage material: First, 100 parts by mass of polyvinyl acetate and 900 parts by mass of deionized water were dissolved by stirring at 80℃ for 2 hours to obtain a 10% polyvinyl acetate solution A. Next, 900 parts by mass of n-eicosane were heated to a molten state and mixed with 100 parts by mass of phenylsilane (PhTES) to prepare a composite phase change liquid B. Then, 380 parts by mass of solution B were added to 570 parts by mass of the polyvinyl acetate solution, along with 47.5 parts by mass of K12, so that the composite phase change liquid B was suspended in the polyvinyl acetate solution A in the form of small droplets to obtain a dispersion C. 420 parts by weight of straw powder were impregnated in 580 parts by weight of dispersion C. 4 parts by weight of ethylene glycol butyl ether were added for thorough impregnation. Under the condition of maintaining the temperature, 100 parts by weight of K2SiO3·2H2O were added and stirred evenly. The pH was adjusted to 12 and maintained at 60℃ for 4 hours. After further drying and pulverization, straw powder-shaped n-eicosane phase change heat storage material was obtained.

[0102] Granulation of metakaolin and straw powder-shaped phase change thermal storage material: 200 parts by weight of straw powder-shaped n-eicosane phase change thermal storage material and 600 parts by weight of metakaolin are mixed evenly. 180 parts by weight of water are added and stirred. 20 parts by weight of 4-amino-1-naphthalenesulfonic acid are added and stirred evenly. The mixture is then removed and granulated using a granulator or tablet press. The granulated particles are then naturally air-dried or oven-dried to obtain straw powder-shaped n-eicosane phase change thermal storage material particles.

[0103] Modification of fly ash: Add 40 parts by weight of salicylic acid to 480 parts by weight of water and stir evenly. Add 480 parts by weight of fly ash and stir evenly at high speed. After stirring at 60℃ for 2 hours, filter, wash with water, dry, grind, and pass through a 100-mesh sieve to obtain modified fly ash.

[0104] Preparation of fly ash-shaped organic phase change heat storage material: 580 parts by weight of n-eicosane were heated to 40°C and completely melted. After stirring evenly, 420 parts by weight of fly ash were added. After stirring for 30 minutes, the mixture was allowed to cool naturally until solidification, ensuring that the fly ash fully absorbed the phase change material. After cooling, the surface of the mixture was observed. If crystals appeared, the mixture was in a supersaturated state, thus obtaining the fly ash-shaped n-eicosane phase change heat storage material.

[0105] Preparation of Geopolymer Straw Phase Change Blocks (Precast Panels): According to the mass ratio, 68 parts by mass of sodium silicate were added to 32 parts by mass of saturated sodium carbonate solution, and the mixture was poured into a stirring vessel and stirred until the activator solution was homogeneous. After cooling to room temperature, the mixture was stirred again and then placed in an ultrasonic cleaner and vibrated for 5 minutes to obtain an alkali activator solution. 100 parts by mass of metakaolin, 334 parts by mass of straw powder-shaped n-eicosane phase change heat storage material particles, 202 parts by mass of fly ash-shaped n-eicosane phase change heat storage material, 180 parts by mass of fly ash, 100 parts by mass of alkali activator, and 70 parts by mass of deionized water were mixed and stirred in a disperser at 1200 r / min for 30 min. Then, 5 parts by mass of 4-amino-1-naphthalenesulfonic acid and 9 parts by mass of melamine-formaldehyde resin were added, and the mixture was stirred again at 1200 r / min for 15 min. The homogeneous slurry was poured into a mold, and the insulation bricks were formed using vibration molding. The YLT5-20 type concrete used in the vibration molding process was vibrated for 1 minute and cured at 20℃ and relative humidity greater than 90% until it had sufficient strength. The resulting geopolymer straw phase change blocks (precast slabs) were then demolded.

[0106] Example 7

[0107] Preparation of straw powder-based phase change thermal storage material particles: straw ultrafine processing and alkaline surface treatment

[0108] The vine stalks were coarsely crushed into 2cm lengths using a jaw crusher. They were then soaked in a 510 parts by weight of straw powder and a 490 parts by weight of saturated sodium carbonate solution for 24 hours at 70℃. After rinsing with clean water and drying, the straw powder was further finely crushed using an ultrafine grinding mill or similar equipment to a particle size of 1.5mm.

[0109] Preparation of straw powder-based phase change thermal storage material: First, 100 parts by mass of xanthan gum and 900 parts by mass of deionized water were dissolved by stirring at 80℃ for 2 hours to obtain a 10% xanthan gum solution A. Next, 900 parts by mass of n-octadecane were heated to a molten state and mixed with 100 parts by mass of TEOS (tetraethoxysilane) to prepare a composite phase change liquid B. Then, 480 parts by mass of solution B were added to 520 parts by mass of xanthan gum solution, along with 50 parts by mass of E-1300, so that the composite phase change liquid B was suspended in the xanthan gum solution A in the form of small droplets to obtain a dispersion C. 450 parts by weight of straw powder were impregnated in a dispersion C containing 550 parts by weight. 5 parts by weight of ammonium lignin sulfonate were added for thorough impregnation. Under the condition of maintaining the temperature, 100 parts by weight of MgSO4·7H2O were added and stirred evenly. The pH was adjusted to 12 and maintained at 60℃ for 4 hours. After further drying and pulverization, straw powder-shaped n-octadecane phase change heat storage material was obtained.

[0110] Granulation of metakaolin and straw powder-shaped phase change thermal storage material: 300 parts by weight of straw powder-shaped n-octadecane phase change thermal storage material and 500 parts by weight of metakaolin are mixed evenly. 190 parts by weight of water are added and stirred. 10 parts by weight of KR-55 are added and stirred evenly. The mixture is then removed and granulated using a granulator or tablet press. The granulated particles are then naturally air-dried or oven-dried to obtain straw powder-shaped n-octadecane phase change thermal storage material particles.

[0111] Modification of fly ash: Add 20 parts by weight of tartaric acid to 240 parts by weight of water and stir evenly. Add 240 parts by weight of fly ash and stir evenly at high speed. After stirring at 60℃ for 2 hours, filter, wash with water, dry, grind, and pass through a 100-mesh sieve to obtain modified fly ash.

[0112] Preparation of fly ash-shaped organic phase change heat storage material: 560 parts by weight of n-octadecane were heated to 35°C and completely melted. After stirring evenly, 440 parts by weight of fly ash were added. After stirring for 30 minutes, the mixture was allowed to cool naturally until solidification, ensuring that the fly ash fully absorbed the phase change material. After cooling, the surface of the mixture was observed. If crystals appeared, the mixture was in a supersaturated state, thus obtaining fly ash-shaped n-octadecane phase change heat storage material.

[0113] 3. Preparation of geopolymer straw phase change blocks (precast slabs): According to the mass ratio, straw powder is used to shape phase change heat storage materials.

[0114] Preparation of geopolymer straw phase change blocks (precast slabs): 72 parts by weight of sodium potassium hydroxide were added to 28 parts by weight of saturated potassium silicate solution. The mixture was then poured into a stirring vessel and stirred until the activator solution was homogeneous. After cooling to room temperature, the mixture was stirred again and then placed in an ultrasonic cleaner and vibrated for 5 minutes to obtain an alkali activator solution. 110 parts by weight of metakaolin, 280 parts by weight of straw powder-shaped n-octadecane phase change heat storage material particles, 240 parts by weight of fly ash-shaped n-octadecane phase change heat storage material, 150 parts by weight of fly ash, 100 parts by weight of alkali activator, and 100 parts by weight of deionized water were mixed and stirred in a disperser at 1200 r / min for 30 min. Then, 5 parts by weight of KR-55 and 15 parts by weight of phenolic resin were added, and the mixture was stirred at 1200 r / min for another 15 min. The homogeneous slurry was poured into a mold, and the insulation bricks were formed by vibration. The YLT5-20 type concrete used in the vibration molding process was vibrated for 1 minute and cured at 20℃ and relative humidity greater than 90% until it had sufficient strength. The resulting geopolymer straw phase change blocks (precast slabs) were then demolded.

[0115] The straw phase change block (precast slab) wall and its associated solar greenhouse (Mohe area, Heilongjiang Province) are positively correlated with the latitude, temperature, and winter solstice solar altitude angle of the greenhouse location. Based on extensive statistical equations, the latitude of Mohe is 53.1°, and the altitude is approximately 600 meters. This greenhouse primarily produces winter-season vegetables. The optimal front roof angle is calculated as α = 23.5° + (53.1° - 40°) × 0.86 + 1 + 0 ≈ 35.8°; the rear slope angle is chosen as β = 40°. The span is L = 14m, M = 2.4m, the horizontal projection length of the rear roof is L2 = 2.4 * cos40 = 1.84m, and H = (14 - 1.84) * =8.5m, h=8.5-1.84* .

[0116] 4.2 Determination of the thickness of straw phase change block (precast slab) wall

[0117] Calculate the thickness δw of the block (precast slab), taking δw = 50 cm and λw = 0.062 w / mk; for the 800 μm nano-thermal conductive coating, take λ... h =10w / mk; XPS thickness for external wall insulation =150mm, λeps =0.028w / mk. ∑R λ =(0.8*10 -3 / 10+δw / 0.062+0.15 / 0.028)=(5.357+δw / 0.062,K0=1 / (Ri+∑R λ +Re),K0=1 / (0.115+5.357+δw / 0.062+0.0443)=1 / (5.517+δw / 0.062)=1 / 13.58=0.073w / (m 2 K)≤1.0w / (m2.K). The outer wall of the greenhouse is made of straw phase change block (precast slab) with a thickness of 500 mm. The outer wall is equipped with 150 mm thick extruded polystyrene insulation board. The greenhouse is composed of an indoor floor, a 150 mm thick extruded polystyrene insulation board cold-proof wall to the local frost line, a low wall on the sunny side and a roof panel.

[0118] An 800µm thick nano-thermal conductive coating (λ≥10w / mk) is sprayed onto the phase change heat storage layer.

[0119] Table 1 shows the comparison data between the straw ultrafine processing and alkaline surface treatment in Examples 1 to 7 and the untreated straw surface in the corresponding examples.

[0120] Table 1. Effects of alkaline treatment on the surface of straw on the mechanical properties of straw powder and the bond between straw powder and cement.

[0121]

[0122] Table 1. Mechanical properties of straw powder and the bond between straw powder and cement after alkali treatment on the surface of straw.

[0123] The results show that the treated straw exhibits significant improvements in tensile strength, compressive strength, Young's modulus, density, hardness, impact toughness, and interfacial bond strength. Furthermore, microstructural analysis of the interface reveals a denser transition zone and a more robust interfacial bond in the treated straw. The treated straw also exhibits significantly reduced flexural strength, water absorption, and water absorption rate, ensuring its excellent performance for use in building blocks.

[0124] Table 2 shows the performance parameters of the straw powder shaped phase change heat storage materials prepared in Examples 1 to 7, including the straw with alkaline surface treatment and the straw without encapsulation treatment.

[0125] Table 2. Performance parameters of straw powder shaped phase change thermal storage materials

[0126] Table 3. Performance Indicators of Straw Powder Shaped Phase Change Thermal Storage Materials

[0127] Table 2 shows the performance data of the straw powder shaped phase change heat storage material: the unencapsulated group consists of straw that has not undergone the alkali surface treatment step of the straw powder shaped phase change heat storage material preparation step; the leakage rate of the encapsulated phase change material after the straw powder shaped phase change heat storage material preparation step is significantly reduced, and the stability time is significantly improved; the phase change temperature drift, water absorption, and moisture content are significantly reduced, and the thermal conductivity, heat storage capacity, tensile strength, flexural strength, and ductility are all significantly increased. Table 3 shows the performance indicators of the straw powder shaped phase change heat storage material, which indicates that its average latent heat of phase change during the melting and crystallization process is high.

[0128] The performance parameters of the straw powder shaped phase change heat storage materials obtained in Examples 1 to 7 after granulation with metakaolin and with or without coupling agent are as follows: hydroxyl reduction rate, tensile strength improvement rate, flexural strength improvement rate, thermal decomposition temperature improvement (°C), and contact angle change. The values ​​are the percentage of hydroxyl reduction, tensile strength improvement, flexural strength improvement, thermal decomposition temperature improvement, and contact angle change after adding coupling agent. The contact angle is significantly reduced after adding coupling agent.

[0129] Table 4 Granulation of metakaolin and straw powder shaped phase change thermal storage materials

[0130] Table 4 shows the granulation properties of metakaolin and straw powder-based phase change thermal storage materials. The untreated group is the untreated group.

[0131] The results of the coupling agent treatment group showed that the coupling agent had a significant effect. The addition of the coupling agent increased the tensile strength, flexural strength, and thermal decomposition temperature (°C) of the straw powder shaped phase change thermal storage material particles.

[0132] The contact angle change is significantly reduced; the chemical bond strength, water resistance, mechanical properties, and weather resistance are high; the coefficient of thermal expansion is small; the degree of chemical reaction is significant; and the interface morphology is smooth.

[0133] Table 5. Performance Indicators of Straw Phase Change Blocks (Precast Slabs)

[0134]

[0135] Table 5 shows that the straw phase change block (precast panel) wall has excellent performance characteristics.

[0136] Heat storage coefficient, latent heat of phase change, and strength grade. Table 5 shows that the performance indicators of straw phase change blocks (precast slabs) have high strength and excellent latent heat of phase change.

[0137] Table 6. Performance Indicators of Straw Phase Change Block (Precast Slab) Walls

[0138]

[0139] Table 7. Temperature Indicators Inside Greenhouses Constructed with Straw Phase Change Blocks (Precast Panels)

[0140] As can be seen from Table 7, the temperature index inside the greenhouse of the straw phase change block (precast panel) wall can be achieved when the phase change block wall of the present invention is applied to the greenhouse. When the minimum outdoor temperature can reach below -33℃, the minimum indoor temperature can still be above 12.5℃.

[0141] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A geopolymer straw phase change block, characterized in that, The raw materials include the following weight percentages: 25%-35% straw powder shaped phase change thermal storage material particles, 15%-25% fly ash shaped organic phase change thermal storage material, 10%-20% fly ash, 10%-20% metakaolin, 10%-15% alkali activator, 0.1-1.0% coupling agent, 0.9%-2.5% polymer cementitious material, and 9%-12% water; The straw powder-shaped phase change heat storage material particles are obtained by the following method: 1) the straw powder is shaped into phase change heat storage material particles. 1) The straw surface is alkali-liquefied and crushed to less than 2 mm to obtain straw powder; 2) The polymer adhesive and deionized water are stirred and dissolved to prepare adhesive solution A; 3) The first organic phase change heat storage material is heated to a molten state and mixed with silicon source material to prepare composite phase change liquid B; 4) Adhesive solution A and emulsifier are added to composite phase change liquid B solution so that composite phase change liquid B is suspended in adhesive solution A in the form of droplets to obtain dispersion C; 5) Straw powder and dispersion C are stirred and mixed evenly, a penetrant is added to make it fully impregnated and penetrated, a coagulant solution is added and stirred evenly, dried and crushed to obtain straw powder shaped phase change heat storage material; 6) The straw powder shaped phase change heat storage material is mixed with metakaolin, a coupling agent and water are added and stirred evenly, the mixture is granulated and dried to obtain straw powder shaped phase change heat storage material particles; Fly ash-based shaped organic phase change thermal storage materials are obtained through the following methods: 1) Fly ash is treated with organic acids 1) Soak, wash, dry, grind and sieve; 2) Mix the treated fly ash and the second organic phase change heat storage material, heat until melted and stirred, cool and solidify into powder.

2. The geopolymer straw phase change block according to claim 1, characterized in that, The alkali used in the alkali liquefaction treatment is any one of sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium silicate, sodium carbonate, and sodium bicarbonate. The mass ratio of straw to alkali is 1:1 to 1:3, the soaking time is more than 24 hours, and the temperature is 60-80℃.

3. The geopolymer straw phase change block according to claim 1, characterized in that, The polymeric adhesive is any one of polyvinyl alcohol, urea-formaldehyde resin, xanthan gum, guar gum, soybean protein glue, polyvinyl acetate, and VAE; the adhesive solution A has a mass percentage of 8-12%, and the stirring and dissolving temperature is 75-85℃ for more than 2 hours.

4. The geopolymer straw phase change block according to claim 1, characterized in that, The silicon source material used is any one of tetraethoxysilane, methyltriethoxysilane, methyltrimethoxysilane, methylsilane, ethylsilane, or benzylsilane; the first organic phase change heat storage material is heated to a molten state with a mass ratio of 9:1 to the silicon source material; adhesive solution A is added to the composite phase change liquid B solution, with a mass ratio of 1:1.5 between the composite phase change liquid B solution and the adhesive solution A; the emulsifier is 5% of the total mass of the composite phase change liquid B solution and the adhesive solution A.

5. The geopolymer straw phase change block according to claim 4, characterized in that, The emulsifier is any one of Tween80, Tween40, Tween20, OP-10, K12, E-1300, and MES.

6. The geopolymer straw phase change block according to claim 1, characterized in that, The straw powder and dispersion C are mixed evenly at a mass ratio of 1:1 to 1:3, and a penetrant of 0.1-0.5% of the total mass of the straw powder and dispersion C is added; the coagulant is 10% of the total mass of the straw powder and dispersion C.

7. The geopolymer straw phase change block according to claim 6, characterized in that, The penetrant is any one of sodium di-2-octyl maleate sulfonate, BX splitting powder, naphthalene sulfonate NNO, fatty alcohol polyoxyethylene ethers, ammonium lignin sulfonate, ethylene glycol butyl ether, and dimethyl sulfoxide; the coagulant is any one of Na2SO4·10H2O, Na2SiO3·9H2O, K2SO4·5H2O, K2SiO3·2H2O, MgSO4·7H2O, ZnSO4·7H2O, and CaCl2·6H2O.

8. The geopolymer straw phase change block according to claim 1, characterized in that, The straw powder shaped phase change heat storage material and metakaolin are mixed at a mass ratio of 1:1 to 1:3; the amount of coupling agent is 1%-5% of the mass of the straw powder shaped phase change heat storage material; the coupling agent is any one of KH-550, KH-560, KH-570, KR-55, Lica-38, 1-amino-2-naphthalenesulfonic acid, and 4-amino-1-naphthalenesulfonic acid.

9. The geopolymer straw phase change block according to claim 1, characterized in that, The amount of water used in the organic acid soaking step is water with a mass ratio of 1:1 to fly ash, stirred at 50-70℃ for 2-3 hours, and passed through an 80-120 mesh sieve; the organic acid is any one of oxalic acid, phytic acid, citric acid, salicylic acid, malic acid, tannic acid, and tartaric acid; the second organic phase change heat storage material is any one or two of n-alkanes.

10. A geopolymer straw phase change block according to any one of claims 1 to 9, characterized in that, The alkaline activator is any one or more of sodium silicate, potassium silicate, lithium silicate, aluminum silicate, sodium hydroxide, potassium hydroxide, calcium hydroxide, and sodium carbonate; the polymer gelling material is any one of urea-formaldehyde resin, phenolic resin, melamine-formaldehyde resin, acrylic resin, and VAE resin.

11. A method for preparing geopolymer straw phase change blocks, characterized in that, Alkali activator and saturated alkali solution were introduced into a stirred tank at a ratio of 4:1 to 2:1 to prepare activator solutions with different moduli. After cooling to room temperature, the solutions were stirred and then subjected to ultrasonic vibration to obtain alkali activator solutions. Straw powder-shaped phase change heat storage material particles, fly ash-shaped organic phase change heat storage material, fly ash, metakaolin, the alkali activator solution, and deionized water are mixed and stirred, placed in a disperser, and then coupling agent and polymer cementing material are added in sequence. The uniformly stirred slurry is poured into a mold, vibrated and cured, and demolded to obtain geopolymer straw phase change blocks.

Images