Thermal power solid waste-based large supercooling phase change material as well as preparation method and application thereof

Abstract

The invention provides a thermal power solid waste-based large supercooling phase change material as well as a preparation method and application thereof. The thermal power solid waste-based large supercooling phase change material comprises an inner core and a coating layer, the inner core is of a porous structure and comprises a phase change medium, fly ash and furnace slag; the coating layer coats at least part of the outer surface of the inner core, and the coating layer comprises silicon dioxide. According to the thermal power solid waste-based large supercooled phase-change material, the thermal power solid waste fly ash and the slag are used for preparing the phase-change material, the solid waste utilization rate is larger than or equal to 80%, and the raw material cost is reduced while the pollution problem is solved; the supercooling degree of the obtained solid-waste-based large supercooling phase change material is larger than or equal to 80 DEG C, the solid-waste-based large supercooling phase change material can be supercooled in the environment of-30 DEG C to be kept in a liquid state for 6 months or above and is far higher than that of a traditional material, the heat preservation cost is reduced by 30% or above, the heat storage density is larger than or equal to 250 J / g, and the long-period and high-density requirements of cross-seasonal energy storage are met. And meanwhile, the silicon dioxide coating layer can reduce solid-liquid interface energy through a high contact angle and block crystallization spreading.

Description

Technical Field

[0001] This application belongs to the intersection of thermal power solid waste resource utilization and phase change energy storage, and in particular relates to a supercooled phase change material based on thermal power solid waste, its preparation method and application, which is suitable for scenarios such as building heating in cold northern regions, waste heat recovery in industrial parks, and cross-seasonal utilization of solar energy. Background Technology

[0002] Thermal power plants generate large amounts of solid waste during power generation, such as fly ash, slag, and desulfurization gypsum, exceeding 1 billion tons annually. Stockpiling these wastes occupies land and pollutes the environment. Furthermore, energy consumption for cooling, heating, and air conditioning in buildings accounts for 40% of total energy consumption. There is an urgent need for efficient cooling and heating solutions. Seasonal energy storage can resolve the contradictions in energy supply and demand in terms of time, space, and intensity. It has advantages such as high renewable energy utilization efficiency, reduced peak-season energy procurement expenditures, and enhanced energy self-sufficiency. Seasonal energy storage requires utilizing or enhancing the supercooling of phase change materials to store heat in summer and provide heating in winter. However, traditional phase change materials such as sodium acetate trihydrate and paraffin have low supercooling (<50℃), are prone to spontaneous crystallization leading to latent heat loss, and have low heat storage density (<200 J / g), requiring large-capacity containers, increasing land occupation and cost.

[0003] Preparing novel environmentally friendly functional materials based on solid waste is an effective measure for the high-value utilization of solid waste resources. The mullite (3Al2O3·2SiO2) and the silica-alumina components of the glassy structure in fly ash can regulate crystallization kinetics. Currently, there is a lack of relevant technologies for applying thermal power plant solid waste to inter-seasonal energy storage and effectively controlling supercooling to meet practical needs. Therefore, developing a phase change material with high supercooling suitable for inter-seasonal energy storage using thermal power plant solid waste has significant practical importance and broad application prospects. Summary of the Invention

[0004] In view of this, one objective of this application is to provide a supercooled phase change material based on thermal power solid waste to solve the problems of insufficient supercooling of phase change materials, low utilization rate of solid waste, and large system heat loss in existing cross-seasonal energy storage technologies.

[0005] Another objective of this application is a method for preparing supercooled phase change materials based on thermal power solid waste.

[0006] Another objective of this application is to provide a double-layered vacuum container.

[0007] Another objective of this application is to provide a cross-seasonal energy storage system.

[0008] Another objective of this application is to provide a control method for a cross-seasonal energy storage system.

[0009] To achieve the above objectives, the first aspect of this application proposes a supercooled phase change material based on thermal power solid waste, comprising: The core is a porous structure comprising a phase change medium, fly ash, and slag. A coating layer covering at least a portion of the outer surface of the core, the coating layer comprising silicon dioxide.

[0010] In some embodiments, the phase change medium accounts for 80-90% by mass in the supercooled phase change material based on thermal power solid waste.

[0011] In some embodiments, the total mass percentage of the fly ash and the slag in the thermal power solid waste-based supercooled phase change material is 8-15%.

[0012] In some embodiments, the mass ratio of the fly ash to the slag is (2-4):1, and can be optionally 3:1.

[0013] In some embodiments, the total mass percentage of the silicon dioxide in the thermal power solid waste-based supercooled phase change material is 2-5%.

[0014] In some embodiments, the thickness of the coating layer is 2-5 nm.

[0015] In some embodiments, the melting point of the phase change medium is 80-150°C.

[0016] In some embodiments, the phase change medium includes at least one of erythritol and sodium sulfate decahydrate.

[0017] In some embodiments, the fly ash has at least one of the following characteristics: (1) In the fly ash, the mass ratio of silicon dioxide to aluminum oxide is greater than 2.5 and less than 4; (2) Loss on ignition is below 5 wt%; (3) The particle size range is below 50 μm, and can be selected as 40-50 μm; (4) The fly ash is fly ash that has been acid washed to remove impurities.

[0018] In some embodiments, the slag has at least one of the following characteristics: 1) Calcium oxide content is above 35 wt%; 2) Particle size range is below 100μm.

[0019] In some embodiments, the surface contact angle of the coating layer is greater than 120°.

[0020] In some embodiments, the supercooling degree of the supercooled phase change material based on thermal power solid waste is 80-100°C.

[0021] The second aspect of this application proposes a method for preparing a supercooled phase change material based on thermal power solid waste, comprising: Fly ash and slag are mixed to obtain a solid waste mixture powder; The phase change medium is melted and added to the solid waste mixture powder, then ultrasonically dispersed to obtain a suspension; A silicon source is dispersed in a solvent, and then a silica coating layer is formed on the surface of the suspension using a sol-gel method to obtain a coated suspension. The coated suspension was freeze-dried to obtain a supercooled phase change material based on thermal power solid waste.

[0022] In some embodiments, the mass ratio of the solid waste mixture powder, the phase change medium, and the silicon source is (8-15):(80-90):(8-22).

[0023] In some embodiments, the melting point of the phase change medium is 80-150°C.

[0024] In some embodiments, the phase change medium includes at least one of erythritol and sodium sulfate decahydrate.

[0025] In some embodiments, the silicon source includes at least one of tetraethyl orthosilicate, tetramethoxysilane, and propyl orthosilicate, and may be selected as tetraethyl orthosilicate.

[0026] In some embodiments, the mass ratio of fly ash to slag is (2-4):1, and can be optionally 3:1.

[0027] In some embodiments, the fly ash has at least one of the following characteristics: (1) In the fly ash, the mass ratio of silicon dioxide to aluminum oxide is greater than 2.5 and less than 4; (2) Loss on ignition is below 5 wt%; (3) The particle size range is below 50 μm, and can be selected as 40-50 μm.

[0028] In some embodiments, the slag has at least one of the following characteristics: 1) Calcium oxide content is above 35 wt%; 2) Particle size range is below 100μm.

[0029] In some embodiments, the freeze-drying temperature is -50°C to -30°C, and optionally -40°C.

[0030] In some embodiments, the vacuum degree of the freeze-drying is 1-10 Pa.

[0031] In some embodiments, the freeze-drying time is 8-16 hours, optionally 12 hours.

[0032] In some embodiments, the mass ratio of the silicon source to the solvent is 1:(3-5), and optionally 1:4.

[0033] In some embodiments, the solvent includes at least one of an ethanol solution, an isopropanol solution, and an ethylene glycol dimethyl ether solution, with an ethanol solution being optional.

[0034] In some embodiments, the preparation method of the supercooled phase change material based on thermal power solid waste further includes: Before mixing fly ash and slag, the fly ash is acid-washed and then washed with water until neutral, and then ball-milled to the first target particle size.

[0035] In some embodiments, the first target particle size is below 50 μm, and may be 40-50 μm.

[0036] In some embodiments, the preparation method of the supercooled phase change material based on thermal power solid waste further includes: Before mixing fly ash and slag, the slag is crushed and screened to the second target particle size.

[0037] In some embodiments, the second target particle size is below 100 μm.

[0038] A third aspect of this application proposes a double-layer vacuum container, comprising: An inner tube, on which at least one triggering unit is mounted; An outer shell is fitted around the inner tube, forming a sandwich space between them; the triggering unit is provided in the sandwich space, and a phase change material is encapsulated in the space other than the triggering unit in the sandwich space. The phase change material is the thermal power solid waste-based supercooled phase change material described in the first aspect of this application or the thermal power solid waste-based supercooled phase change material prepared by the preparation method of the thermal power solid waste-based supercooled phase change material described in the second aspect of this application.

[0039] In some embodiments, the inner tube is a corrugated aluminum tube, a pure copper tube, or a 6063 aluminum alloy tube.

[0040] In some embodiments, the inner tube has a wall thickness of 1.3-1.7 mm.

[0041] In some embodiments, the thermal conductivity of the inner tube is 200-390 W / (m•K), and can be optionally 237 W / (m•K).

[0042] In some embodiments, the triggering unit is an ultrasonic transducer, which may be an ultrasonic transducer with a power density of 45-55 W / m² and a frequency of 20-30 kHz.

[0043] In some implementations, when the number of triggering units is greater than one, the spacing between two adjacent triggering units is 25-35 cm.

[0044] In some embodiments, the inner surface of the outer shell is provided with a heat insulation layer, and the heat insulation layer and the inner tube form the interlayer space.

[0045] In some embodiments, the thickness of the outer shell is 2.5-3.5 mm.

[0046] In some embodiments, the outer shell is made of Q235 steel, Q345 steel, or 304 stainless steel.

[0047] In some embodiments, the interlayer space is an annular interlayer space or a U-shaped interlayer space.

[0048] In some embodiments, the vacuum level of the double-walled vacuum container is 1-10 Pa.

[0049] In some embodiments, an anti-corrosion coating is provided between the inner surface of the outer shell and the heat insulation layer; optionally, the anti-corrosion coating is an anti-corrosion coating with a heat resistance temperature greater than 150°C.

[0050] In some embodiments, the thickness of the insulation layer is 35-50 mm.

[0051] In some embodiments, the insulation layer is a fly ash-expanded perlite composite insulation layer, a fly ash-vermiculite composite insulation layer, or a slag-alumina silicate fiber composite insulation layer, and can be selected as a fly ash-expanded perlite composite insulation layer.

[0052] In some embodiments, the fly ash content in the fly ash-expanded perlite composite insulation layer is above 40 wt%, and / or the fly ash-expanded perlite composite insulation layer is an insulation layer that has undergone CO2 mineralization treatment at 0.3-0.8 MPa for 1.5-3 h.

[0053] The fourth aspect of this application proposes a cross-seasonal energy storage system, comprising: A heat supply unit is used to provide heat; Multiple energy storage units are provided for receiving heat from the heat supply unit; the energy storage unit is the double-layer vacuum container described in the third aspect of this application; the inlet of the inner tube of the energy storage unit is connected to the heat supply unit; valves are provided between the inner tubes of the multiple energy storage units to control the series or parallel connection of the inner tubes of the multiple energy storage units. A heat exchange module is a heat exchanger connected to a building underfloor heating / air conditioning system. The primary side of the heat exchanger is connected to the inner tube and forms a loop with the inner tube. A first circulation pump is installed on the loop. The secondary side of the heat exchanger is connected to the evaporator side and the condenser side of the heat pump through a three-way valve and a second circulation pump. The condenser side is connected to the building underfloor heating / air conditioning system. The control unit includes a temperature sensor group, a meteorological data receiving module, a PLC controller, and a Long Short-Term Memory Network (LSTM) thermal demand prediction model, and is equipped with an overcooling triggering algorithm. The temperature sensor group, the meteorological data receiving module, and the LSTM thermal demand prediction model are connected to the input terminal of the PLC controller. The temperature sensors include a first temperature sensor, a second temperature sensor, a third temperature sensor, a fourth temperature sensor, and a fifth temperature sensor. The first temperature sensor is connected to the energy storage unit, the second temperature sensor is used to test the ambient temperature, the third temperature sensor is used to test the building's indoor temperature, the fourth sensor is used to test the temperature on the primary side, and the fifth sensor is used to test the temperature on the secondary side. The output terminal of the PLC controller is connected to the triggering units of all valves, three-way valves, the first circulation pump, the second circulation pump, the heat pump, and all energy storage units.

[0054] In some embodiments, the heat supply unit is a solar collector or an industrial waste heat exchanger.

[0055] In some embodiments, the heat exchanger is a plate heat exchanger.

[0056] In some embodiments, the heat exchanger has a thermal efficiency greater than 90% and withstands a pressure of 1.0-2.5 MPa.

[0057] In some embodiments, the heat pump is an air source heat pump, and the three-way valve is an electric three-way ball valve.

[0058] In some embodiments, the first temperature sensor, the fourth temperature sensor, and the fifth temperature sensor are PT100 platinum resistance temperature sensors, and the second temperature sensor and the third temperature sensor are digital temperature sensors.

[0059] In some embodiments, the cross-seasonal energy storage system further includes a metering module for recording stored or released heat energy and transmitting it remotely.

[0060] The fifth aspect of this application proposes a control method for a cross-seasonal energy storage system, comprising: The temperature sensor collects the temperature of the phase change material, the ambient temperature, the building's indoor temperature, the temperature of the primary side, and the temperature of the secondary side in real time, and feeds back the temperature information to the PLC controller. The meteorological data collection module acquires climate information for a preset future time period and feeds the climate information back to the PLC controller; the meteorological information includes temperature, humidity, and solar radiation; The long short-term memory network heat demand prediction model predicts heat demand based on the temperature information and the climate information, and feeds back the heat demand information to the PLC controller; the heat demand information includes at least one of the phase change material temperature, building heat load and ambient temperature; The temperature of the phase change material is defined as T. PCM The PLC controller dynamically switches between the following operating modes (1) to (5) based on the thermal demand information: 1) Direct heating mode: When T PCM When the temperature is ≥90℃, the valve is opened to release heat directly. The PLC starts the first circulation pump and the second circulation pump and shuts down the heat pump. The heat output power is ≥30kW. 2) Multiple energy storage units in series mode: When 70℃≤TPCM<90℃, the PLC opens the valve of the inner tube of the energy storage unit, so that the inner tubes of multiple energy storage units are connected in series to release heat in a coordinated manner, with a total heat output power ≥20kW; 3) Heat pump coupling mode: When 40℃≤TPCM<70℃, the heat pump is started to raise the evaporation temperature to 50±2℃, COP≥3.2; 4) Ultrasonic triggering mode: When 20℃≤TPCM<40℃ and the building heat load is >80% of the preset value, the ambient temperature is ≤5℃, and the temperature gradient of the phase change material is >5℃ / cm, the ultrasonic transducer array is activated, and crystallization is induced within 10s; 5) Heat pump direct supply mode: When TPCM<20℃, switch to independent heat pump heating, with a heating temperature ≥45℃.

[0061] The supercooled phase change material based on thermal power solid waste described in this application can bring at least the following beneficial effects: 1. Phase change materials (PCMs) are prepared using fly ash and slag from thermal power plants, achieving a solid waste utilization rate of ≥80%. This solves pollution problems while reducing raw material costs (by 40% compared to pure PCMs). The resulting solid waste-based supercooled PCM has a supercooling degree of ≥80℃ and can remain liquid for more than 6 months in a -30℃ environment (i.e., stability >6 months), far exceeding traditional materials (such as sodium acetate trihydrate, which has a supercooling degree of <50℃ and stability of <3 months). This reduces insulation costs by more than 30%, and the thermal storage density is ≥250 J / g, meeting the long-term, high-density requirements for cross-seasonal energy storage. Simultaneously, the silica coating layer acts as an interface modifier, reducing the solid-liquid interface energy through a high contact angle (≥120°) and blocking crystallization propagation.

[0062] 2. Erythritol (melting point 118℃, latent heat 340 J / g), sodium sulfate decahydrate (Na2SO4) Sodium sulfate decahydrate (10H₂O, 32.4℃, latent heat 250 J / g) serves as a phase change medium and is the core carrier for heat storage. Fly ash and slag act as nucleation inhibitors. After acid washing, fly ash exposes Al-O-Si active sites, which form a hydrogen bond network with the hydroxyl groups of erythritol, delaying crystallization (inhibiting heterogeneous nucleation). Meanwhile, the water of crystallization molecules in sodium sulfate decahydrate can form hydrogen bonds (such as HO…O) with the Al-O-Si active sites on the fly ash surface through their hydroxyl groups (OH), effectively inhibiting crystallization and achieving high subcooling. CaO in the slag can further enhance the hydrogen bonding effect.

[0063] The preparation method of supercooled phase change material based on thermal power solid waste described in this application has at least the following beneficial effects: 1. Phase change materials (PCMs) are prepared using fly ash and slag from thermal power plants, achieving a solid waste utilization rate of ≥80%. This solves pollution problems while reducing raw material costs (by 40% compared to pure PCMs). The resulting solid waste-based supercooled PCM has a supercooling degree of ≥80℃ and can remain liquid for more than 6 months in a -30℃ environment (i.e., stability >6 months), far exceeding traditional materials (such as sodium acetate trihydrate, which has a supercooling degree of <50℃ and stability of <3 months). This reduces insulation costs by more than 30%, and the thermal storage density is ≥250 J / g, meeting the long-term, high-density requirements for cross-seasonal energy storage. Simultaneously, the silica coating layer acts as an interface modifier, reducing the solid-liquid interface energy through a high contact angle (≥120°) and blocking crystallization propagation.

[0064] 2. Erythritol (melting point 118℃, latent heat 340 J / g), sodium sulfate decahydrate (Na2SO4) Sodium sulfate decahydrate (10H₂O, 32.4℃, latent heat 250 J / g) serves as a phase change medium and is the core carrier for heat storage. Fly ash and slag act as nucleation inhibitors. After acid washing, fly ash exposes Al-O-Si active sites, which form a hydrogen bond network with the hydroxyl groups of erythritol, delaying crystallization (inhibiting heterogeneous nucleation). Meanwhile, the water of crystallization molecules in sodium sulfate decahydrate can form hydrogen bonds (such as HO…O) with the Al-O-Si active sites on the fly ash surface through their hydroxyl groups (OH), effectively inhibiting crystallization and achieving high subcooling. CaO in the slag can further enhance the hydrogen bonding effect.

[0065] 3. Freeze-drying can create a porous structure, which enhances heat transfer efficiency.

[0066] 4. Acid washing of fly ash can remove soluble impurities, and subsequent ball milling can increase the specific surface area.

[0067] 5. This method can increase the utilization rate of solid waste from thermal power plants to 80%, and 800 kg of phase change materials can be prepared from each ton of solid waste, significantly reducing raw material costs.

[0068] The double-layer vacuum container described in this application has at least the beneficial effects of the supercooled phase change material based on thermal power solid waste and the preparation method of the supercooled phase change material based on thermal power solid waste described in this application.

[0069] The cross-seasonal energy storage system and its control method described in this application, in addition to having the beneficial effects of the thermal power solid waste-based supercooled phase change material and the preparation method of the thermal power solid waste-based supercooled phase change material described in this application, can also bring at least the following beneficial effects: 1. This application employs a system-level synergistic protection mechanism combining a solid waste insulation layer, ultrasonic triggering, and a five-level control mode. The double-layer vacuum container with a CO2 mineralized insulation layer results in a heat loss rate ≤4.5% / month, superior to water-based thermal storage systems (heat loss rate >8% / month). The ultrasonic triggering unit, coupled with an intelligent control algorithm, achieves a heat release response time <10s and a triggering efficiency ≥95%, resolving the issues of low efficiency and complex operation associated with traditional triggering methods (such as seed crystal injection).

[0070] 2. Five operating modes adapt to different temperature ranges, improving thermal efficiency by 20%; the LSTM heat demand prediction model predicts heat demand and adjusts the operating strategy in advance, reducing energy consumption by 15% compared to traditional PID control. Simultaneously, high energy storage density significantly reduces floor space. Cycle life ≥2000 cycles, meeting usage requirements for over 15 years, reducing total lifespan cost by 50%.

[0071] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0072] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings. in: Figure 1 This application illustrates an exemplary method for preparing supercooled phase change materials based on thermal power solid waste.

[0073] Figure 2 This is a schematic diagram of the structure of a double-layer vacuum container shown in an exemplary embodiment of this application.

[0074] Figure 3 This is a schematic diagram of the structure of a cross-seasonal energy storage system, which is an exemplary embodiment of this application.

[0075] Figure 4 This is a flowchart illustrating a cross-seasonal energy storage system control method as an exemplary embodiment of this application.

[0076] Figure label: 1-Inner tube; 2-Outer shell; 3-Anti-corrosion coating; 4-Insulation layer; 5-Phase change material; 6-Ultrasonic element; 100-Heat supply unit; 200-Energy storage unit; 300-Control unit; 301-Temperature sensor group; 302-Meteorological data receiving module; 303-PLC controller; 400-Heat exchange module; 401-Building underfloor heating / air conditioning system; 402-Heat exchanger. Detailed Implementation

[0077] Embodiments of this application are described in detail below, with examples of these embodiments illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting it.

[0078] In this application, the disclosure of numerical ranges includes all values ​​throughout the range and the disclosure of further subdivisions of the range, including the endpoints and subranges given for these ranges.

[0079] Unless otherwise specified, all raw materials and equipment involved in this application are those that can be manufactured commercially or by known methods; and all methods involved are conventional methods unless otherwise specified.

[0080] <Supercooled Phase Change Materials Based on Thermal Power Plant Solid Waste> The supercooled phase change material based on thermal power solid waste in this application includes a core and a coating layer. The core has a porous structure and includes a phase change medium, fly ash, and slag. The coating layer covers at least a portion of the outer surface of the core and includes silicon dioxide.

[0081] In the embodiments of this application, fly ash and slag act as nucleation inhibitors, and silica acts as an interface modifier. Therefore, it can be understood that the supercooled phase change material based on thermal power solid waste in the embodiments of this application consists of a phase change medium, a nucleation inhibitor, and an interface modifier.

[0082] In some embodiments, the phase change medium is 80-90% by mass in the supercooled phase change material based on thermal power solid waste, including but not limited to 82%, 85% or 87%.

[0083] In some embodiments, the melting point of the phase change medium is 80-150°C, including but not limited to 90°C, 100°C, 110°C, 120°C, 130°C or 140°C.

[0084] For example, the phase change medium includes, but is not limited to, erythritol and sodium sulfate decahydrate (Na2SO4). At least one of the following: 10H2O. Optionally, erythritol has a melting point of 118℃ and a latent heat of 340 J / g; sodium sulfate decahydrate has a melting point of 32.4℃ and a latent heat of 250 J / g.

[0085] In some embodiments, the total mass percentage of the fly ash and slag in the supercooled phase change material based on thermal power solid waste is 8-15%, including but not limited to 9%, 10%, 11%, 12%, 13%, or 14%, and optionally 12-13%. A lower limit of 8% for the total content of fly ash and slag allows for a supercooling of ≥80℃. If the total content of fly ash and slag is less than 8%, the number of fly ash and slag particles dispersed in the phase change medium is insufficient, resulting in a limited specific surface area and an inability to form a continuous and effective hydrogen bond network. An upper limit of less than 15% is to maintain a high heat storage density of ≥250 J / g; excessively high fly ash and slag content leads to a decrease in the overall material's heat storage density. The range of 8-15% (preferably 12-13%) achieves a balance between supercooling and heat storage density, ensuring structural stability and cycle life. Within this range, the supercooling is stable at at least 80-100℃, the heat storage density remains at 250-290 J / g, the melt-crystallization cycle is ≥2000 times, and the latent heat retention rate is >90%.

[0086] In some embodiments, the mass ratio of fly ash to slag is (2-4):1, including but not limited to 2.5:1, 3:1, or 3.5:1, with 3:1 being a possible choice. Within this range, the number of Al-O-Si active sites and the CaO reinforcing component achieve optimal synergy, ensuring both supercooling and stability.

[0087] In some embodiments, the total mass percentage of silicon dioxide in the thermal power plant solid waste-based supercooled phase change material is 2-5%, including but not limited to 2.5%, 3%, 3.5%, 4%, or 4.5%, and optionally 3.5-4%. Within this range, the total mass percentage of silicon dioxide in the thermal power plant solid waste-based supercooled phase change material can form a complete coating layer on the core surface without significantly reducing heat transfer efficiency.

[0088] In some embodiments, the thickness of the coating layer is 2-5 nm, including but not limited to 2.5 nm, 3 nm, 3.5 nm, 4 nm, or 4.5 nm, and can be selected as 3.5-4 nm. A coating layer thickness within this range ensures the mechanical strength of the coating layer without excessively increasing thermal resistance.

[0089] In some embodiments, the fly ash has at least one of the following characteristics: (1) In the fly ash, the mass ratio of silicon dioxide to aluminum oxide is greater than 2.5; (2) Loss on ignition is below 5 wt%; (3) The particle size range is below 50 μm, and can be selected as 40-50 μm; (4) The fly ash is fly ash that has been acid washed to remove impurities.

[0090] For example, in the fly ash, the mass ratio of silicon dioxide to aluminum oxide includes, but is not limited to, 3, 3.5, 4, 4.5, or 5, and can be selected as 3-4. A mass ratio of silicon dioxide to aluminum oxide within the above range ensures the availability of OH or Si-O sites for hydrogen bonding between SiO2 and the phase change medium, as well as Al-O sites provided by Al2O3.

[0091] For example, the loss on ignition of the fly ash includes, but is not limited to, less than 4 wt%, less than 3 wt%, or less than 2 wt%, etc., to maximize the removal of inert impurities. Higher purity of the active ingredient makes the nucleation inhibition effect more reliable.

[0092] For example, acid washing to remove impurities was performed using 1 mol / L HCl for 2 hours. After acid washing, the fly ash exposed Al-O-Si active sites, forming a hydrogen bond network with the hydroxyl groups of erythritol, thus delaying crystallization (inhibiting heterogeneous nucleation). Na2SO4 The water molecules in 10H2O can form hydrogen bonds (such as HO…O) with active sites such as Al-O-Si on the surface of fly ash through their hydroxyl groups (OH), thereby effectively inhibiting crystallization and achieving a large degree of supercooling.

[0093] In some embodiments, the slag has at least one of the following characteristics: 1) The calcium oxide (CaO) content is above 35 wt%; 2) Particle size range is below 100μm.

[0094] For example, the calcium oxide content in the slag includes, but is not limited to, 40 wt% or more, 45 wt% or more, 50 wt% or more, or 55 wt% or more, and can be selected as 50-55 wt%. This content can form a fly ash network framework, and the slag Ca²⁺ content... + Strengthen the collaborative structure of nodes to obtain high and stable supercooling.

[0095] For example, the particle size range of the slag includes, but is not limited to, less than 90 μm, less than 80 μm, or less than 70 μm. Sufficiently fine slag particle size can achieve a large specific surface area and uniform dispersion in the phase change medium.

[0096] In some embodiments, the surface contact angle of the coating layer is greater than 120°, including but not limited to greater than 125°, greater than 130°, or greater than 135°. A high contact angle means that the coating layer has superhydrophobic properties, which is a guarantee for the long-term stable supercooling of the material.

[0097] As an optional example, the core is composed of a phase change medium, fly ash, and slag, with the phase change medium being erythritol; the coating layer covers at least a portion of the outer surface of the core, and the coating layer is silica. The phase change medium is selected from erythritol (melting point 118℃, latent heat 340 J / g) or Na₂SO₄. 10H2O (melting point 32.4℃, latent heat 250 J / g), serving as the core carrier for thermal energy storage, comprises 80-90% by mass. Nucleation inhibitors are a 3:1 mixture of fly ash and slag. After acid washing, the fly ash exposes Al-O-Si active sites, forming a hydrogen bond network with the hydroxyl groups of erythritol, thus delaying crystallization (inhibiting heterogeneous nucleation). CaO in the slag further enhances hydrogen bonding, accounting for 8-15% of the total. Interface modifiers, consisting of SiO2 or a graphene coating (2-5 nm thick), reduce the solid-liquid interface energy through a high contact angle (≥120°), blocking crystallization propagation, accounting for 2-5%. This material has a supercooling of ≥80℃ and can remain stably liquid for over 6 months at -30℃, with a thermal energy storage density of ≥250 J / g, meeting the long-term, high-density requirements for cross-seasonal energy storage.

[0098] In some embodiments, the supercooling degree of the supercooled phase change material based on thermal power solid waste is above 80°C, including but not limited to above 90°C or above 100°C, and can be selected as 80-100°C. This range covers winter ambient temperatures from frigid zones to most temperate zones, providing ample design margin.

[0099] The embodiments of this application based on thermal power solid waste-based supercooled phase change materials can bring at least the following beneficial effects: 1. Phase change materials (PCMs) are prepared using fly ash and slag from thermal power plants, achieving a solid waste utilization rate of ≥80%. This solves pollution problems while reducing raw material costs (by 40% compared to pure PCMs). The resulting solid waste-based supercooled PCM has a supercooling degree of ≥80℃ and can remain liquid for more than 6 months in a -30℃ environment (i.e., stability >6 months), far exceeding traditional materials (such as sodium acetate trihydrate, which has a supercooling degree of <50℃ and stability of <3 months). This reduces insulation costs by more than 30%, and the thermal storage density is ≥250 J / g, meeting the long-term, high-density requirements for cross-seasonal energy storage. Simultaneously, the silica coating layer acts as an interface modifier, reducing the solid-liquid interface energy through a high contact angle (≥120°) and blocking crystallization propagation.

[0100] 2. Erythritol (melting point 118℃, latent heat 340 J / g), sodium sulfate decahydrate (Na2SO4) Sodium sulfate decahydrate (10H₂O, 32.4℃, latent heat 250 J / g) serves as a phase change medium and is the core carrier for heat storage. Fly ash and slag act as nucleation inhibitors. After acid washing, fly ash exposes Al-O-Si active sites, which form a hydrogen bond network with the hydroxyl groups of erythritol, delaying crystallization (inhibiting heterogeneous nucleation). Meanwhile, the water of crystallization molecules in sodium sulfate decahydrate can form hydrogen bonds (such as HO…O) with the Al-O-Si active sites on the fly ash surface through their hydroxyl groups (OH), effectively inhibiting crystallization and achieving high subcooling. CaO in the slag can further enhance the hydrogen bonding effect.

[0101] <Preparation Method of Supercooled Phase Change Materials Based on Thermal Power Plant Solid Waste> The preparation method of the supercooled phase change material based on thermal power solid waste in this application embodiment can be used to prepare the supercooled phase change material based on thermal power solid waste in this application embodiment.

[0102] The preparation method of the supercooled phase change material based on thermal power solid waste in this application includes the following steps: S101. Mix fly ash and slag to obtain solid waste mixed powder; S102. After melting the phase change medium, add it to the solid waste mixed powder and disperse it by ultrasonication to obtain a suspension; S103. The silicon source is dispersed in a solvent, and then a silica coating layer is formed on the surface of the suspension using the sol-gel method to obtain the coated suspension. S104. The coated suspension is freeze-dried to obtain a supercooled phase change material based on thermal power solid waste.

[0103] In some embodiments, the mass ratio of the solid waste mixture, the phase change medium, and the silicon source is (8-15):(80-90):(8-22), including but not limited to 11.5:85:15.2, 10:85:21.7, or 12:85:13. This range can simultaneously achieve a supercooling degree ≥80℃, a heat storage density ≥285 J / g, and an intact coating layer.

[0104] In some embodiments, the melting point of the phase change medium is 80-150°C, including but not limited to 90°C, 100°C, 110°C, 120°C, 130°C, or 140°C. This range covers the temperature range of common renewable energy sources and industrial waste heat. Excessively high melting points will increase the overall system cost and are not conducive to improving energy efficiency.

[0105] In some embodiments, the phase change medium includes, but is not limited to, erythritol and sodium sulfate decahydrate (Na2SO4). At least one of the following: 10H2O. Optionally, erythritol has a melting point of 118℃ and a latent heat of 340 J / g; sodium sulfate decahydrate has a melting point of 32.4℃ and a latent heat of 250 J / g.

[0106] In some embodiments, the silicon source includes, but is not limited to, at least one of tetramethoxysilane, propyl orthosilicate, etc., and may be selected as tetramethoxysilane. In the embodiments of this application, the silicon source is a precursor of silicon dioxide.

[0107] In some embodiments, the mass ratio of the silicon source to the solvent is 1:(3-5), including but not limited to 1:3.5, 1:4, or 1:4.5, with 1:4 being a possible choice. This ratio allows the hydrolysis-condensation reaction of the silicon source to become mild and controllable, resulting in a uniformly thick, dense SiO2 coating layer with a high contact angle.

[0108] In some embodiments, the solvent includes, but is not limited to, at least one of ethanol solution, isopropanol solution, ethylene glycol dimethyl ether solution, etc., and may be selected as ethanol solution.

[0109] In the embodiments of this application, in S103, a silica coating layer is formed on the surface of the suspension using the sol-gel method. The preparation of silica aerogel using the sol-gel method mainly includes four key steps: sol preparation, gelation, aging, and drying. First, a silicon source (such as tetraethyl orthosilicate) is dissolved in a solvent (such as ethanol), and a catalyst (such as ammonia or hydrochloric acid) is added to carry out hydrolysis and condensation reactions, forming a low-viscosity sol. Subsequently, the sol is allowed to stand or heated, and then gradually gels to form a wet gel with a three-dimensional network structure. Aging treatment is then used to enhance structural stability. Finally, the solvent is removed by methods such as supercritical drying, atmospheric pressure drying, or freeze-drying, retaining the nanoporous structure, ultimately yielding silica aerogel. This method, by precisely controlling the reaction conditions and drying process, can prepare aerogel materials with low thermal conductivity and high porosity, making them widely applicable in fields such as building insulation and industrial thermal insulation.

[0110] It should be noted that in the embodiments of this application, the freeze-drying of silica aerogel in the sol-gel method is only for the silica coating layer itself; while the freeze-drying in the subsequent step S104 is for the entire coated suspension system.

[0111] The conversion of tetraethyl orthosilicate (TES) to silica involves two consecutive and concurrent reactions: hydrolysis and condensation. Hydrolysis activates the TES molecules (Si(OC₂H₅)₄ + 4H₂O → Si(OH)₄ + 4C₂H₅OH). The presence of water is the driving force of the reaction, and hydrochloric acid can be added as a catalyst to accelerate the hydrolysis rate. The condensation reaction links the active monomers produced by hydrolysis together, forming a Si-O-Si silica network (Si(OH)₄ + Si(OH)₄ → (HO)₃Si-O-Si(OH)₃ + H₂O). Continuous stirring ensures that the reactants are evenly distributed rather than agglomerating into large particles. Ethanol is used to slow down the hydrolysis rate, making the reaction milder and more controllable, which helps to form a structurally regular coating layer.

[0112] As an optional example, the specific process of forming a silica coating layer on the surface of the suspension using the sol-gel method in S103 is as follows: dispersing a silicon source in a solvent to obtain a dispersion; adding the dispersion dropwise to the suspension and aging it for a certain period of time. Specifically, it includes the following steps: A) Dispersion preparation: Mix the silicon source (e.g., tetraethyl orthosilicate) and solvent (e.g., ethanol) at a mass ratio of 1:4 and stir for 5-10 min until clear; then add the catalyst (e.g., 0.1-0.5 mol / L hydrochloric acid) dropwise to adjust the pH of the system to 3-4 (acidic catalysis, suitable for slow hydrolysis to control the coating thickness), and continue stirring for 15-20 min to form a uniform and transparent sol dispersion (ensuring that tetraethyl orthosilicate is initially hydrolyzed into silanol groups, preparing for subsequent polycondensation). B) Coating reaction and dispersion synergistically: The above sol dispersion is added dropwise to the suspension (phase change medium + solid waste mixed powder, refer to the 300W ultrasound in Example 1) in an ultrasonically dispersed state at a rate of 1-2 drops / second. After the addition is completed, ultrasonic dispersion is continued for 20-30 minutes. C) Aging and solidification: After stopping the ultrasonic treatment, the system is placed in a constant temperature environment of 25-35℃ for 2-4 hours to allow the silanol groups attached to the particle surface to undergo a condensation reaction (forming a Si-O-Si network), and finally a silica coating layer with a thickness of 2-5nm is formed on the surface of the solid waste particles / phase change medium in the suspension.

[0113] In some embodiments, the mass ratio of fly ash to slag is (2-4):1, including but not limited to 2.5:1, 3:1 or 3.5:1, etc., and can be selected as 3:1.

[0114] In some embodiments, the fly ash has at least one of the following characteristics: (1) In the fly ash, the mass ratio of silicon dioxide to aluminum oxide is greater than 2.5 and less than 4; (2) Loss on ignition is below 5 wt%; (3) The particle size range is below 50 μm, and can be selected as 40-50 μm.

[0115] For example, in the fly ash, the mass ratio of silicon dioxide to aluminum oxide includes, but is not limited to, 3, 3.5, 4, 4.5 or 5, and can be selected as 3-4.

[0116] For example, the loss on ignition of the fly ash includes, but is not limited to, less than 4 wt%, less than 3 wt%, or less than 2 wt%.

[0117] In some embodiments, the slag has at least one of the following characteristics: 1) Calcium oxide content is above 35 wt%; 2) Particle size range is below 100μm.

[0118] For example, the calcium oxide content in the slag includes, but is not limited to, more than 40 wt%, more than 45 wt%, more than 50 wt%, or more than 55 wt%, and can be selected as 50-55 wt%.

[0119] For example, the particle size range of the slag includes, but is not limited to, less than 90 μm, less than 80 μm, or less than 70 μm.

[0120] In the embodiments of this application, fly ash and slag serve as nucleation inhibitors.

[0121] In some embodiments, the freeze-drying temperature is from -50°C to -30°C, including but not limited to -45°C, -40°C or -35°C, and can be selected as -40°C.

[0122] In some embodiments, the vacuum degree of the freeze-drying is below 10 Pa, including but not limited to below 8 Pa or below 5 Pa, and can be selected as 1-10 Pa.

[0123] In some embodiments, the freeze-drying time is 8-16 hours, including but not limited to 10 hours or 14 hours, and can be 12 hours.

[0124] In some embodiments, the preparation method of the supercooled phase change material based on thermal power solid waste further includes: Before mixing fly ash and slag, the fly ash is acid-washed and then washed with water until neutral, and then ball-milled to the first target particle size.

[0125] For example, the acid used for pickling the fly ash includes, but is not limited to, hydrochloric acid, dilute sulfuric acid, etc., and 1 mol / L hydrochloric acid can be selected.

[0126] For example, the acid washing time for the fly ash is 1 hour.

[0127] For example, neutral is pH=7.

[0128] In some embodiments, the first target particle size is below 50 μm, and may be 40-50 μm.

[0129] In some embodiments, the preparation method of the supercooled phase change material based on thermal power solid waste further includes: Before mixing fly ash and slag, the slag is crushed and screened to the second target particle size.

[0130] In some embodiments, the second target particle size is below 100 μm.

[0131] As an optional example, such as Figure 1 As shown, the preparation method of supercooled phase change materials based on thermal power solid waste includes: a. Solid waste pretreatment: Fly ash is acid-washed with 1mol / L HCl for 2h (to remove soluble impurities) and ball-milled to a particle size ≤45±5μm (to increase specific surface area); slag is crushed to a particle size ≤100μm; the ball-milled fly ash and the crushed slag are mixed at a ratio of 3:1 to obtain solid waste mixed powder.

[0132] b. Melt the phase change medium erythritol at 120℃.

[0133] c. Add 12wt% solid waste mixed powder to the molten phase change medium erythritol, and ultrasonically disperse at 300W for 30min (to ensure uniform suspension of solid waste powder) to obtain a uniform suspension.

[0134] d. Interface coating: Add tetraethyl orthosilicate-ethanol solution (tetraethyl orthosilicate to ethanol mass ratio 1:4) dropwise to the suspension. The sol-gel reaction forms a SiO2 layer (thickness controlled at 2-5 nm) to reduce the interface energy.

[0135] e. Freeze-dry at -40℃ and dry under vacuum ≤10Pa for 12h to form a porous structure (enhancing heat transfer efficiency) to obtain a supercooled composite phase change material.

[0136] The preparation method of supercooled phase change material based on thermal power solid waste in this application has at least the following beneficial effects: 1. Phase change materials (PCMs) are prepared using fly ash and slag from thermal power plants, achieving a solid waste utilization rate of ≥80%. This solves pollution problems while reducing raw material costs (by 40% compared to pure PCMs). The resulting solid waste-based supercooled PCM has a supercooling degree of ≥80℃ and can remain liquid for more than 6 months in a -30℃ environment (i.e., stability >6 months), far exceeding traditional materials (such as sodium acetate trihydrate, which has a supercooling degree of <50℃ and stability of <3 months). This reduces insulation costs by more than 30%, and the thermal storage density is ≥250 J / g, meeting the long-term, high-density requirements for cross-seasonal energy storage. Simultaneously, the silica coating layer acts as an interface modifier, reducing the solid-liquid interface energy through a high contact angle (≥120°) and blocking crystallization propagation.

[0137] 2. Erythritol (melting point 118℃, latent heat 340 J / g), sodium sulfate decahydrate (Na2SO4) Sodium sulfate decahydrate (10H₂O, 32.4℃, latent heat 250 J / g) serves as a phase change medium and is the core carrier for heat storage. Fly ash and slag act as nucleation inhibitors. After acid washing, fly ash exposes Al-O-Si active sites, which form a hydrogen bond network with the hydroxyl groups of erythritol, delaying crystallization (inhibiting heterogeneous nucleation). Meanwhile, the water of crystallization molecules in sodium sulfate decahydrate can form hydrogen bonds (such as HO…O) with the Al-O-Si active sites on the fly ash surface through their hydroxyl groups (OH), effectively inhibiting crystallization and achieving high subcooling. CaO in the slag can further enhance the hydrogen bonding effect.

[0138] 3. Freeze-drying can create a porous structure, which enhances heat transfer efficiency.

[0139] 4. Acid washing of fly ash can remove soluble impurities, and subsequent ball milling can increase the specific surface area.

[0140] 5. This method can increase the utilization rate of solid waste from thermal power plants to 80%, and 800 kg of phase change materials can be prepared from each ton of solid waste, significantly reducing raw material costs.

[0141] Double-walled vacuum container Figure 2 This is a schematic diagram of the structure of a double-layer vacuum container shown in an exemplary embodiment of this application.

[0142] like Figure 2 As shown, the double-layer vacuum container of this application embodiment includes an inner tube 1 and an outer shell 2; at least one trigger unit 6 is installed on the inner tube 1; the outer shell 2 is fitted around the inner tube 1, and a sandwich space is formed between the two; the trigger unit is provided in the sandwich space, and a phase change material 5 is encapsulated in the space other than the trigger unit in the sandwich space. The phase change material 5 is a thermal power solid waste-based supercooled phase change material of this application embodiment or a thermal power solid waste-based supercooled phase change material prepared by the preparation method of thermal power solid waste-based supercooled phase change material of this application embodiment.

[0143] In some embodiments, the thermal conductivity of the inner tube 1 is 200-390 W / (m•K), including but not limited to 250 W / (m•K), 300 W / (m•K) or 350 W / (m•K), and can be selected as 237 W / (m•K).

[0144] In some embodiments, the inner tube 1 is a corrugated aluminum tube, a pure copper tube, or a 6063 aluminum alloy tube, and can be selected as a corrugated aluminum tube, and further selected as having a thermal conductivity of 237 W / (m). K) can enhance heat transfer.

[0145] In some embodiments, the wall thickness of the inner tube 1 is 1.3-1.7 mm, including but not limited to 1.4 mm, 1.5 mm or 1.6 mm.

[0146] In some embodiments, the triggering unit is an ultrasonic transducer, which may be an ultrasonic transducer with a power density of 45-55 W / m² and a frequency of 20-30 kHz.

[0147] For example, the power density of the ultrasonic array includes, but is not limited to, 48 W / m² or 52 W / m², and optionally 50 W / m².

[0148] For example, the frequency of the ultrasonic transducer includes, but is not limited to, 22 kHz or 27 kHz, and optionally 25 kHz.

[0149] The ultrasonic transducer breaks the supercooled equilibrium through mechanical vibration, inducing crystallization and heat release. A power density of 50W / m² can ensure triggering within 10 seconds.

[0150] In some implementations, when the number of triggering units is greater than one, the spacing between two adjacent triggering units is 25-35cm, including but not limited to 28cm, 30cm or 32cm.

[0151] In some embodiments, the inner surface of the outer shell 2 is provided with a heat insulation layer 4, and the heat insulation layer 4 and the inner tube 1 form the interlayer space.

[0152] In some embodiments, the thickness of the outer shell 2 is 2.5-3.5 mm, including but not limited to 2.7 mm, 3 mm or 3.2 mm.

[0153] In some embodiments, the outer shell 2 is made of Q235 steel, Q345 steel or 304 stainless steel.

[0154] In the embodiments of this application, the shape of the interlayer space is not limited. Depending on the shape of the outer shell, the shape of the interlayer space varies, and the whole space is either ring-shaped or ring-like. For example, when both the outer shell and the inner tube are cylindrical, the interlayer space is a ring-shaped interlayer space; when both the outer shell and the inner tube are cuboid, the interlayer space is a U-shaped interlayer space.

[0155] In some embodiments, the vacuum degree of the double-layer vacuum container is 1-10 Pa, including but not limited to 3 Pa, 5 Pa or 7 Pa.

[0156] In some embodiments, an anti-corrosion coating 3 is provided between the inner surface of the outer shell 2 and the heat insulation layer 4; optionally, the anti-corrosion coating 3 is an anti-corrosion coating with a heat resistance temperature greater than 150°C.

[0157] For example, the thickness of the anti-corrosion layer is 80-120μm, including but not limited to 90μm, 100μm or 110μm.

[0158] For example, the material of the anti-corrosion layer includes at least one of silicone resin, epoxy phenolic resin, and ceramic matrix composite material. Optionally, the silicone resin includes, but is not limited to, at least one of methylphenyl silicone resin and fluorosilicone resin; the epoxy phenolic resin includes, but is not limited to, at least one of bisphenol A type epoxy-phenolic copolymer (such as Hexion® EPON™ 164) and Novolac epoxy resin (such as Huntsman® Araldite® EPN 1139); and the ceramic matrix composite material includes, but is not limited to, at least one of Al2O3-SiO2 ceramics (such as Aremco® Cerama-Bond™ 571) and Cr2O3-ZrO2 composite coating (plasma sprayed powder).

[0159] In some embodiments, the thickness of the heat insulation layer 4 is 35-50 mm, including but not limited to 37 mm, 40 mm or 43 mm.

[0160] In some embodiments, the insulation layer 4 is a fly ash-expanded perlite composite insulation layer, a fly ash-vermiculite composite insulation layer, or a slag-alumina silicate fiber composite insulation layer, and can be selected as a fly ash-expanded perlite composite insulation layer.

[0161] In some embodiments, the fly ash content in the fly ash-expanded perlite composite insulation layer is above 40 wt%, including but not limited to above 45 wt% or above 50 wt%.

[0162] In some embodiments, the fly ash-expanded perlite composite insulation layer is an insulation layer that has undergone CO2 mineralization treatment at 0.5 MPa for 2 hours.

[0163] The double-layer vacuum container of this application embodiment has at least the beneficial effects of the supercooled phase change material based on thermal power solid waste and the preparation method of the supercooled phase change material based on thermal power solid waste described in this application.

[0164] <Cross-seasonal energy storage systems and their control methods> Figure 3 This is a schematic diagram of the structure of a cross-seasonal energy storage system, which is an exemplary embodiment of this application.

[0165] like Figure 3 As shown, the cross-seasonal energy storage system of this application embodiment includes a heat supply unit 100, multiple energy storage units 200, a control unit 300, and a heat exchange unit 400. Wherein, The heat supply unit 100 is used to supply heat. Exemplarily, the heat supply unit 100 is a solar collector or an industrial waste heat exchanger. If it is a solar collector, a parabolic trough solar collector is preferred; if it is an industrial waste heat exchanger, a shell-and-tube waste heat exchanger is preferred. Optionally, the heat supply unit is connected to the inner tube inlet of the energy storage unit via a heat collection loop with a valve, forming a summer heat collection path from heat supply to the energy storage unit (the heat collection valve is open in summer and closed in winter). Optionally, the heat collection loop valve is an electric ball valve.

[0166] Multiple energy storage units 200 are used to receive heat from the heat supply unit 100; the energy storage unit 200 is a double-layer vacuum container according to an embodiment of this application. Valves are provided between the inner tubes of the multiple energy storage units to control the series or parallel connection of the inner tubes. For example, in summer, parallel valves achieve synchronous heat collection, and in winter, series valves achieve coordinated heat release, meeting the requirements of a multi-tank series connection mode.

[0167] The heat exchange module 400 is a heat exchanger 402 connected to the building underfloor heating / air conditioning system 401. The primary side of the heat exchanger 402 is connected to the inner tube 1 and forms a loop with the inner tube 1. A first circulation pump is installed on the loop. The secondary side of the heat exchanger 402 is connected to the evaporator side and condenser side of the heat pump through a three-way valve and a second circulation pump. The condenser side is connected to the building underfloor heating / air conditioning system 401. The connection between the heat pump evaporator side and the secondary side is used for "heat pump coupling mode" (extracting heat from the phase change material for quality improvement), and the connection between the heat pump condenser side and the secondary side is used for "heat pump direct supply mode" (extracting heat from the environment). The three-way valve realizes loop switching.

[0168] The control unit 300 includes a temperature sensor group 301, a meteorological data receiving module 302, a PLC controller 303, and a long short-term memory network thermal demand prediction model (i.e., an LSTM thermal demand prediction model), and is equipped with an overcooling trigger algorithm. The temperature sensor group 301, the meteorological data receiving module 302, and the long short-term memory network thermal demand prediction model are connected to the input terminal of the PLC controller 303. The temperature sensor group 301 includes a first temperature sensor, a second temperature sensor, a third temperature sensor, a fourth temperature sensor, and a fifth temperature sensor. The first temperature sensor is connected to the energy storage unit 200, the second temperature sensor is used to test the ambient temperature, the third temperature sensor is used to test the indoor temperature of the building, the fourth sensor is used to test the temperature on the primary side, and the fifth sensor is used to test the temperature on the secondary side. The output terminal of the PLC controller is connected to the trigger units of all valves, three-way valves, the first circulating pump, the second circulating pump, the heat pump, and all energy storage units to realize mode switching control.

[0169] In the embodiments of this application, a first circulation pump and a second circulation pump are respectively provided in the primary side loop and the secondary side loop of the heat exchanger. The phase change material is in the interlayer space and is immersed in the heat exchange module. It exchanges heat with the fluid inside the pipe through the pipe wall.

[0170] In some implementations, the temperature sensor group 301, the meteorological data receiving module 302, and the LSTM heat demand prediction model are all connected to the input of the PLC controller via an industrial bus.

[0171] In some embodiments, the heat exchanger 402 is a plate heat exchanger.

[0172] In some embodiments, the heat exchanger 402 has a thermal efficiency greater than 90%, which can adapt to different terminal heating needs.

[0173] In some embodiments, the heat exchanger 402 is subjected to a pressure of 1.0-2.5 MPa, including but not limited to 1.5 MPa or 2 MPa.

[0174] In some embodiments, the heat pump is an air source heat pump, and the three-way valve is an electric three-way ball valve.

[0175] In some embodiments, the first temperature sensor, the fourth temperature sensor, and the fifth temperature sensor are PT100 platinum resistance temperature sensors, and the second temperature sensor and the third temperature sensor are digital temperature sensors.

[0176] In some embodiments, the cross-seasonal energy storage system further includes a metering module for recording stored or released heat energy and transmitting it remotely.

[0177] For example, the accuracy of the metering module is ±1%.

[0178] For example, the metering module preferably uses an electromagnetic heat meter with a measurement accuracy of ±1%, records parameters including instantaneous heat power and cumulative stored / released heat, and performs remote data transmission.

[0179] For example, the accuracy of the first temperature sensor, the second temperature sensor, the third temperature sensor, the fourth temperature sensor and the fifth temperature sensor are all ±0.5℃. The meteorological data receiving module 302 can collect temperature, humidity, solar radiation information and so on within a preset future time, wherein the preset future time can be the next 72 hours, etc., and can be selected as 72 hours.

[0180] In the embodiments of this application, multiple energy storage units can be connected in parallel to collect heat in summer and in series to release heat in winter.

[0181] The control method for a cross-seasonal energy storage system according to embodiments of this application includes the following steps: The temperature sensor collects the temperature of the phase change material, the ambient temperature, the building's indoor temperature, the temperature of the primary side, and the temperature of the secondary side in real time, and feeds back the temperature information to the PLC controller. The meteorological data collection module acquires climate information for a preset future time period and feeds the climate information back to the PLC controller; the meteorological information includes temperature, humidity, and solar radiation; The long short-term memory network heat demand prediction model predicts heat demand based on the temperature information and the climate information, and feeds back the heat demand information to the PLC controller; the heat demand information includes at least one of the phase change material temperature, building heat load and ambient temperature; The temperature of the phase change material is defined as T. PCM The PLC controller dynamically switches between the following operating modes (1) to (5) based on the thermal demand information: 1) Direct heating mode: When T PCMAt ≥90℃, the heat exchange valve (i.e. the valves located between the inner tubes of each energy storage unit) is opened to release heat directly. The PLC starts the first circulation pump and the second circulation pump and shuts down the heat pump, with a heat output power ≥30kW. 2) Multiple energy storage units in series mode: When 70℃≤TPCM<90℃, the PLC opens the valve of the inner tube of the energy storage unit, so that the inner tubes of multiple energy storage units are connected in series to release heat in a coordinated manner, with a total heat output power ≥20kW; 3) Heat pump coupling mode: When 40℃≤TPCM<70℃, the heat pump is started to raise the evaporation temperature to 50±2℃, COP≥3.2; 4) Ultrasonic triggering mode: When 20℃≤TPCM<40℃ and the building heat load is >80% of the preset value, the ambient temperature is ≤5℃, and the temperature gradient of the phase change material is >5℃ / cm, the ultrasonic transducer array is activated, and crystallization is induced within 10s; 5) Heat pump direct supply mode: When TPCM<20℃, switch to independent heat pump heating, with a heating temperature ≥45℃.

[0182] PCM usually stands for Phase Change Material.

[0183] For example, the future time is preset to 72 hours in the future.

[0184] In the embodiments of this application, the PLC controller uses an LSTM (Long Short-Term Memory) model to predict heat demand and provide a basis for switching modes. LSTM is a deep learning model specifically designed for processing time-series data, and its core function is to "remember long-term dependencies." During the cross-seasonal cycle of heat collection in summer and heat release in winter, LSTM can correlate energy supply and demand patterns at different time periods. By inputting time-series data such as historical building heat load, ambient temperature and humidity, and phase change material temperature, it learns and predicts the heat demand for the next 72 hours, providing a decision-making basis for switching between five operating modes (such as predicting the winter heating peak in advance and adjusting the ultrasonic triggering timing).

[0185] For data acquisition, temperature sensors collect real-time data on the phase change material temperature, ambient temperature, and building indoor temperature to monitor building heat demand. Simultaneously, a meteorological data receiving module acquires climate data such as temperature, humidity, and solar radiation for the next 72 hours. The PLC controller receives the collected data, predicts the results, and combines them with threshold settings to output control signals. The LSTM heat demand prediction model integrated into the PLC, by inputting historical heat load and climate data, outputs the heat demand trend for the next 72 hours. Mode switching is achieved by switching the heat exchange loop on and off via control signals output from the PLC.

[0186] Phase change material temperature (T) PCM The temperature is between 40°C and 70°C. At this temperature, the system activates its own heat pump, using this energy storage unit as the high-temperature heat source for the heat pump. The heat pump involved in this application does not... Figure 3 The winning bid identified it as an independent functional unit integrated with or directly connected in series with the "heat exchange module" in the system loop. Its function is to upgrade the medium-low temperature heat (40-70℃) released by the phase change material to the high temperature (50-60℃) required for building heating, thereby reducing the loss of heating temperature difference.

[0187] Evaporation temperature refers to the evaporation temperature of the refrigerant in the evaporator of the system heat pump. The evaporator of this system heat pump absorbs heat from a phase change material at 40-70℃, so its evaporation temperature can be set at a high level of around 50℃, thereby achieving COP≥3.2.

[0188] The conditions for activating the trigger unit include: input parameters such as the building's real-time heat load (collection frequency 1 min / time), ambient temperature (error ≤ 0.3℃), and phase change material temperature gradient (resolution 0.1℃ / cm). The trigger logic is that when the three parameters simultaneously meet the threshold conditions, the PLC controller outputs a 24V trigger signal, the ultrasonic transducer works continuously for 10 seconds and then automatically stops, and a heat release completion signal is fed back after crystallization is completed.

[0189] It should be noted that the ultrasonic transducer will not be activated if the heat load meets the standard but the ambient temperature is 10℃ (not in winter), or if the ambient temperature meets the standard but the heat load is insufficient, to ensure the necessity and effectiveness of triggering.

[0190] As an optional example, the specific process by which the PLC controller dynamically switches between five operating modes based on the heat demand information (phase change material temperature (TPCM), building heat load, and ambient temperature) is as follows: When TPCM ≥ 90℃, switch to direct heating mode. The phase change material temperature is higher than the building heating demand (50-60℃), and the heat exchange valve is opened to release heat directly. When 70℃ ≤ TPCM < 90℃, switch to multi-tank series mode. When the heat of a single tank is insufficient, 3-5 heat storage tanks are connected in series for coordinated heating. When 40℃ ≤ TPCM < 70℃, switch to heat pump coupling mode. Start the heat pump to improve the heat of the phase change material to above 50℃, with COP ≥ 3.2, reducing heat pump energy consumption. When 20℃ ≤ TPCM < 40℃, switch to ultrasonic trigger mode. When the building heat load > 80% of the preset value, the ambient temperature ≤ 5℃, and the temperature gradient > 5℃ / cm, activate the ultrasonic device (25kHz, lasting 10s) to induce crystallization and heat release, with a heat release efficiency ≥ 95%. When TPCM < 20℃, switch to heat pump direct supply mode. When the heat of the phase change material is exhausted, switch to independent heat pump heating to ensure continuous heating.

[0191] The cross-seasonal energy storage system and its control method of this application, in addition to having the beneficial effects of the preparation method of the thermal power solid waste-based supercooled phase change material described in this application, can also bring at least the following beneficial effects: 1. This application employs a system-level synergistic protection mechanism combining a solid waste insulation layer, ultrasonic triggering, and a five-level control mode. The double-layer vacuum container with a CO2 mineralized insulation layer results in a heat loss rate ≤4.5% / month, superior to water-based thermal storage systems (heat loss rate >8% / month). The ultrasonic triggering unit, coupled with an intelligent control algorithm, achieves a heat release response time <10s and a triggering efficiency ≥95%, resolving the issues of low efficiency and complex operation associated with traditional triggering methods (such as seed crystal injection).

[0192] 2. Five operating modes adapt to different temperature ranges, improving thermal efficiency by 20%; the LSTM heat demand prediction model predicts heat demand and adjusts the operating strategy in advance, reducing energy consumption by 15% compared to traditional PID control. Simultaneously, high energy storage density significantly reduces floor space. Cycle life ≥2000 cycles, meeting usage requirements for over 15 years, reducing total lifespan cost by 50%.

[0193] The following non-limiting embodiments further illustrate certain features of the present technology.

[0194] Example 1: Preparation and Performance Testing of Solid Waste-Based Supercooled Phase Change Materials The raw materials selected were solid waste fly ash from a national power plant (mass ratio SiO2 / Al2O3=2.8, loss on ignition 4.2wt%), slag (CaO content 38wt%), erythritol (purity 99wt%) as the phase change medium, and tetraethyl orthosilicate (TEOS) as the modifier.

[0195] The preparation steps are as follows: First, fly ash is acid-washed with 1 mol / L HCl for 2 hours, then rinsed with deionized water until neutral (pH=7), and then ball-milled to a diameter of 45±5μm; slag (CaO content 38wt%) is crushed and screened to a particle size ≤80μm, and then mixed with ball-milled fly ash and crushed and screened slag at a mass ratio of 3:1 to obtain solid waste mixed powder. 100g of erythritol was melted (120℃), and 12wt% of solid waste mixed powder relative to the mass of erythritol was added. The mixture was ultrasonically dispersed at 300W for 30min. 75g of tetraethyl orthosilicate-ethanol solution (TEOS:EtOH=1:4) was added dropwise to prepare the tetraethyl orthosilicate-ethanol dispersion. 0.1mol / L hydrochloric acid catalyst was added dropwise to the mixture while stirring (300r / min). The pH of the system was adjusted to 3-4, and stirring was continued for 15min to form a uniform and transparent sol precursor. After aging for 2h, a 5nm thick SiO2 coating layer was formed. Finally, the mixture was freeze-dried at -40℃ for 12h to obtain a white porous composite material, which is the supercooled phase change material based on thermal power solid waste in this embodiment.

[0196] DSC testing (cooling rate 0.5℃ / min) showed a supercooling of 82℃ (melting point 118℃, crystallization point 36℃); heat storage density of 285 J / g; no spontaneous crystallization was observed after 6 months in a -30℃ constant temperature chamber; and the latent heat retention rate was 92% after 2000 melt-crystallization cycles.

[0197] Example 2 This embodiment is basically the same as embodiment 1, except that: Erythritol was replaced with sodium sulfate decahydrate and molten at 32.4°C.

[0198] A white porous composite material was prepared using the above method. Its DSC test (cooling rate 0.5℃ / min) showed a supercooling of 80℃ (melting point 32.4℃, crystallization point -53.6℃); a heat storage density of 260 J / g; no spontaneous crystallization was observed after 6 months in a -30℃ constant temperature chamber; and after 2000 melt-crystallization cycles, the latent heat retention rate was 90%.

[0199] Example 3 This embodiment is basically the same as embodiment 1, except that: Add 10 wt% solid waste mixture powder relative to the mass of erythritol.

[0200] A white porous composite material was prepared using the above method. Its DSC test (cooling rate 0.5℃ / min) showed a supercooling of 82.4℃ (melting point 118.2℃, crystallization point 35.8℃); heat storage density of 278 J / g; no spontaneous crystallization was observed after 6 months in a -30℃ constant temperature chamber; and after 2000 melt-crystallization cycles, the latent heat retention rate was [not specified]. Example 4 This embodiment is basically the same as embodiment 1, except that: Add 17 wt% solid waste mixture powder relative to the mass of erythritol.

[0201] A white porous composite material was prepared using the above method. Its DSC test (cooling rate 0.5℃ / min) showed a supercooling of 84.3℃ (melting point 117.8℃, crystallization point 33.5℃); a heat storage density of 252 J / g; no spontaneous crystallization was observed after 6 months in a -30℃ constant temperature chamber; and the latent heat retention rate was 91% after 2000 melt-crystallization cycles.

[0202] Example 5 This embodiment is basically the same as embodiment 1, except that: Solid waste mixed powder is obtained by mixing the ball-milled fly ash and the crushed and screened slag at a mass ratio of 2:1.

[0203] A white porous composite material was prepared using the above method. Its DSC test (cooling rate 0.5℃ / min) showed a supercooling of 81.5℃ (melting point 118℃, crystallization point 81.5℃); a heat storage density of 282 J / g; no spontaneous crystallization was observed after 6 months in a -30℃ constant temperature chamber; and after 2000 melt-crystallization cycles, the latent heat retention rate was 92%.

[0204] Example 6 This embodiment is basically the same as embodiment 1, except that: Solid waste mixed powder is obtained by mixing the ball-milled fly ash and the crushed and screened slag at a mass ratio of 4:1.

[0205] A white porous composite material was prepared using the above method. Its DSC test (cooling rate 0.5℃ / min) showed a supercooling of 85.3℃ (melting point 118.1℃, crystallization point 85.3℃); a heat storage density of 284 J / g; no spontaneous crystallization was observed after 6 months in a -30℃ constant temperature chamber; and after 2000 melt-crystallization cycles, the latent heat retention rate was 94%.

[0206] Example 7 This embodiment is basically the same as embodiment 1, except that: A tetraethyl orthosilicate-ethanol solution (TEOS:EtOH = 1:4) was added dropwise, and the mixture was aged for 2 hours to form a 2 nm thick SiO2 coating layer. The mass of the tetraethyl orthosilicate-ethanol solution added was 45 g.

[0207] A white porous composite material was prepared using the above method. Its DSC test (cooling rate 0.5℃ / min) showed a supercooling of 81℃ (melting point 118.1℃, crystallization point 37.1℃); a heat storage density of 286 J / g; no spontaneous crystallization was observed after 6 months in a -30℃ constant temperature chamber; and after 2000 melt-crystallization cycles, the latent heat retention rate was 90%.

[0208] Example 8 This embodiment is basically the same as embodiment 1, except that: It does not include the process of "acid washing with 1 mol / L HCl for 2 hours, followed by rinsing with deionized water until neutral (pH=7)".

[0209] A white porous composite material was prepared using the above method. Its DSC test (cooling rate 0.5℃ / min) showed a supercooling of 78.8℃ (melting point 117.9℃, crystallization point 39.1℃); a heat storage density of 289 J / g; no spontaneous crystallization was observed after 6 months in a -30℃ constant temperature chamber; and the latent heat retention rate was 87% after 2000 melt-crystallization cycles.

[0210] Comparative Example 1 This comparative example is basically the same as Example 1, except that: The preparation process does not include the step of "firstly, acid washing fly ash with 1 mol / L HCl for 2 hours, rinsing with deionized water until neutral (pH=7), then ball milling to a diameter of 45±5 μm; mixing the ball-milled fly ash with the crushed and screened slag at a mass ratio of 3:1 to obtain solid waste mixed powder." Instead, erythritol is directly melted (120℃) and 12wt% of crushed and screened slag is added.

[0211] The phase change material prepared in this comparative example was tested by DSC (cooling rate 0.5℃ / min) and found to have a supercooling degree of 65℃ (melting point 118℃, crystallization point 65℃); a heat storage density of 275 J / g; after being placed in a constant temperature chamber at -30℃ for 6 months, no spontaneous crystallization was observed; after 2000 melt-crystallization cycles, the latent heat retention rate was 85%.

[0212] Comparative Example 2 This comparative example is basically the same as Example 1, except that: The process does not include "dropping tetraethyl orthosilicate-ethanol solution (TEOS:EtOH=1:4), aging for 2 hours to form a 5nm thick SiO2 coating layer, and finally freeze-drying at -40℃ for 12 hours to obtain a white porous composite material".

[0213] The phase change material prepared in this comparative example was tested by DSC (cooling rate 0.5℃ / min) and found to have a supercooling degree of 50℃ (melting point 118.1℃, crystallization point 68.1℃); a heat storage density of 230 J / g; after being placed in a constant temperature chamber at -30℃ for 6 months, no spontaneous crystallization was observed; after 2000 melt-crystallization cycles, the latent heat retention rate was 80%.

[0214] Application Example 1: Double-walled vacuum container like Figure 2 As shown, the double-layered vacuum container in this application example includes an inner tube 1 and an outer shell 2. Wherein, The inner surface of the outer shell 2 is sequentially layered with an anti-corrosion coating 3 and a heat insulation layer 4. The anti-corrosion coating 3 is made of methylphenyl silicone resin (formed from a methylphenyl silicone resin solution of model SILRES® 601 produced by Wacker Chemie) and has a thickness of 100 μm. The heat insulation layer 4 is a fly ash-expanded perlite composite heat insulation layer with a thickness of 50 mm, which has been mineralized with 0.5 MPa CO2 for 2 hours. The mass ratio of fly ash to expanded perlite in the fly ash-expanded perlite composite heat insulation layer is 7:3, and the thermal conductivity of the fly ash-expanded perlite composite heat insulation layer is 0.038 W / (m•K). The outer shell 2 is made of Q235 steel with a thickness of 3.0 mm. The outer shell 2 is a heat storage tank with a diameter of 1.5 m × height of 3 m and a volume of 5.3 m³, which can hold 4.2 tons of PCM.

[0215] Six triggering units 6 are installed on the inner tube 1. The triggering units 6 are ultrasonic transducers (25kHz, power density of 50W / m²) and are evenly distributed on the inner tube 6. The total power of the six triggering units 6 is 300W. The inner tube 1 is a corrugated aluminum tube (thermal conductivity of 237 W / (m•K)) with a wall thickness of 1.5mm. The inner tube 1 is fitted inside the outer shell 2, and the inner tube 2 and the surface of the insulation layer 4 away from the anti-corrosion coating 3 form an annular interlayer space. The triggering units 6 are located in the interlayer space, and the space in the interlayer space other than the triggering units is encapsulated with phase change material 5. The phase change material is the supercooled phase change material based on thermal power solid waste prepared in Example 1, and the filling mass of the phase change material is 4.2 tons.

[0216] Application Example 2 The double-layered vacuum container in this application example is basically the same as that in application example 1, except that: The outer shell 2 is a thermal storage tank with a diameter of 2.5m, a height of 4.1m, a thickness of 3.5mm, and a volume of 20m³. It is made of Q235 steel and can hold 17 tons of PCM. The filling mass of the phase change material is 17 tons.

[0217] The inner tube 1 is equipped with 32 trigger units 6, which are ultrasonic transducers (25kHz, power density of 50W / m²) and are evenly distributed on the inner tube 6; the total power of the 32 trigger units 6 is 1.6kW.

[0218] Application Example 3: Operation and Performance Verification of Cross-Seasonal Energy Storage System like Figure 3 As shown, the cross-seasonal energy storage system of this embodiment includes a heat supply unit 100, multiple energy storage units 200, a control unit 300, and a heat exchange unit 400. Among them, The heat supply unit 100 is a solar collector used to provide heat. A trough-type solar collector is selected, with a collection temperature range of 80-180℃ and a collection efficiency ≥75%. The collection valve is an electric ball valve, model Therminol 66. The heat supply unit 100 is connected to the inner tube inlet of the energy storage unit 200 via a collection loop with a valve, forming a summer collection path from heat supply to the energy storage unit (the collection valve is open in summer and closed in winter).

[0219] Four energy storage units 200 are used to receive heat from the heat supply unit 100. Each energy storage unit 200 is a double-walled vacuum container as described in Application Example 1. Valves are provided between the inner tubes of multiple energy storage units to control the series or parallel connection of the inner tubes. For example, in summer, parallel valves achieve synchronous heat collection, while in winter, series valves achieve coordinated heat release, meeting the requirements of a multi-tank series connection mode. (Single tank heat storage capacity: 332.5 kWh; total heat storage capacity of 4 tanks: ≈1330 kWh), meeting the heating needs of a 1000㎡ building (heat load 25 kW) for 53 hours, adapting to the switching logic of parallel heat collection in summer and series heat release in winter.

[0220] The heat exchange module 400 is a heat exchanger 402 connected to the building's underfloor heating / air conditioning system 401. The primary side of the heat exchanger 402 is connected to the inner tube 1, forming a loop with the inner tube 1. A first circulation pump is installed on this loop. The secondary side of the heat exchanger 402 is connected to the evaporator and condenser sides of the heat pump via a three-way valve and a second circulation pump. The condenser side is connected to the building's underfloor heating / air conditioning system 401. The connection between the heat pump evaporator side and the secondary side is used in a "heat pump coupling mode" (extracting heat from the phase change material for quality improvement), while the connection between the heat pump condenser side and the secondary side is used in a "heat pump direct supply mode" (extracting heat from the environment). The three-way valve enables loop switching. The heat exchanger 402 is a plate heat exchanger, model BR20, made of 316 stainless steel, with a thermal efficiency of 92% and a pressure rating of 2.0 MPa. Primary circulation pump (model ISG50-160): flow rate 25 m³ / h, head 32 m, power 3 kW; Secondary circulation pump (model ISG65-160): flow rate 40 m³ / h, head 30 m, power 5 kW, suitable for the flow requirements of plate heat exchangers.

[0221] The control unit 300 includes a temperature sensor group 301, a meteorological data receiving module 302, a PLC controller 303, and a long short-term memory network thermal demand prediction model (i.e., an LSTM thermal demand prediction model), and is equipped with an overcooling trigger algorithm. The temperature sensor 301, meteorological data receiving module 302, and LSTM thermal demand prediction model are connected to the input terminal of the PLC controller 303. The temperature sensor 301 includes a first temperature sensor, a second temperature sensor, a third temperature sensor, a fourth temperature sensor, and a fifth temperature sensor. The first temperature sensor is connected to the energy storage unit 200, the second temperature sensor is used to test the ambient temperature, the third temperature sensor is used to test the indoor temperature of the building, the fourth sensor is used to test the primary side temperature, and the fifth sensor is used to test the secondary side temperature. The temperature sensor group 301, the meteorological data receiving module, and the LSTM thermal demand prediction model are all connected to the input terminal of the PLC controller via an industrial bus. The output terminal of the PLC controller is connected to the trigger units of all valves, three-way valves, the first circulating pump, the second circulating pump, the heat pump, and the energy storage unit to achieve mode switching control. The first, fourth, and fifth temperature sensors are all PT100 platinum resistance thermometers (model WZP-230, accuracy ±0.5℃), while the second and third temperature sensors are both DS18B20 digital sensors (accuracy ±0.2℃); the PLC controller is a Siemens S7-1200.

[0222] The operation process of the cross-seasonal energy storage system in this embodiment is as follows: In summer, heat is collected by heating the phase change material to 130°C to melt it through a solar collector and maintaining it in a subcooled liquid state (ambient temperature 25°C); in winter, heat is released. When the outdoor temperature is -5°C, the building heat load is 25kW (preset value 20kW), and the temperature gradient is 6°C / cm, the system automatically activates the ultrasonic transducer, triggering crystallization within 10 seconds, and the material temperature rises to 118°C; continuous heating is provided, and the heat release from crystallization is maintained for 4 hours (heat supply of 100kWh). After the temperature drops to 18°C, it switches to heat pump assistance, with the heat pump COP=3.5.

[0223] Test results show that the heat loss rate is 4.2% / month (monthly natural heat dissipation ≤ 4.2%); the solar energy utilization rate is 67% (collector efficiency × storage efficiency); and CO2 emissions are reduced by 38 tons / year (compared to electric boiler heating).

[0224] Application Example 4: Cross-Seasonal Utilization of Industrial Waste Heat The cross-seasonal energy storage system in this application example is basically the same as that in application example 4, except that: The heat supply unit 100 provides waste heat (90-110℃) from a thermal power plant.

[0225] The energy storage unit 200 consists of three units, employing the double-walled vacuum container of Application Example 2 (the total PCM volume of all storage units is 60m³). 3 The total amount of phase change material is 51 tons.

[0226] The operational process of this cross-seasonal energy storage system involves a thermal power plant's waste heat (90-110℃) requiring winter heating (50kW load). This system achieves cross-seasonal recovery. The control strategy is based on an LSTM neural network to predict heat demand over the next 72 hours, initiating heat storage when the waste heat temperature is ≥90℃. Operational results show a subcooling duration of 228 days (summer heat storage to winter heat release), with a heat release efficiency of 96.7% (actual heat release / theoretical latent heat). The initial investment is 800,000 yuan, compared to an electric boiler (annual electricity cost of 350,000 yuan), resulting in a payback period of 3.2 years.

[0227] In summary, this application uses fly ash and slag from thermal power plants as core raw materials. Nucleation inhibitors are prepared through hydrochloric acid activation and ultrafine ball milling. These inhibitors are then combined with erythritol / hydrated salt phase change media and modified through vacuum impregnation and SiO2 coating to produce a solid waste-based phase change material with a supercooling degree ≥80℃, excellent performance, and low cost. This material is encapsulated in a double-layer vacuum container. The inner layer is a corrugated aluminum tube, and the outer shell has a fly ash-expanded perlite composite insulation layer. An integrated ultrasonic vibration triggering unit and a climate-predictive-based intelligent control system are used. By dynamically monitoring ambient temperature and building heat load, the supercooled material is triggered to crystallize and release heat, achieving efficient cross-seasonal energy storage for summer use and winter use. The system exhibits high stability, with a heat storage density ≥250 J / g, supercooling stability >6 months, and a heat loss rate ≤4.5% / month. This solves the pollution problem caused by thermal power plant solid waste and overcomes the core challenge of "storing and releasing" energy in cross-seasonal energy storage, making it suitable for building heating and industrial waste heat recovery.

[0228] In this application, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0229] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0230] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A supercooled phase change material based on thermal power solid waste, characterized in that, include: The core is a porous structure comprising a phase change medium, fly ash, and slag. A coating layer covering at least a portion of the outer surface of the core, the coating layer comprising silicon dioxide.

2. The supercooled phase change material based on thermal power solid waste as described in claim 1, characterized in that, The phase change medium accounts for 80-90% of the mass percentage of the supercooled phase change material based on thermal power solid waste. And / or, the total mass percentage of the fly ash and the slag in the supercooled phase change material based on thermal power solid waste is 8-15%; And / or, the mass ratio of the fly ash to the slag is (2-4):1, optionally 3:1; And / or, the total mass percentage of the silicon dioxide in the thermal power solid waste-based supercooled phase change material is 2-5%; And / or, the thickness of the coating layer is 2-5 nm; And / or, the melting point of the phase change medium is 80-150°C; And / or, the phase change medium includes at least one of erythritol and sodium sulfate decahydrate; And / or, the fly ash has at least one of the following characteristics: (1) In the fly ash, the mass ratio of silicon dioxide to aluminum oxide is greater than 2.5 and less than 4; (2) Loss on ignition is below 5 wt%; (3) The particle size range is below 50 μm, and can be selected as 40-50 μm; (4) The fly ash is fly ash that has been acid-washed and impurities removed; And / or, the slag has at least one of the following characteristics: 1) Calcium oxide content is above 35 wt%; 2) Particle size range is below 100μm; And / or, the surface contact angle of the coating layer is greater than 120°; And / or, the supercooling degree of the supercooled phase change material based on thermal power solid waste is 80-100℃.

3. A method for preparing supercooled phase change materials based on thermal power solid waste, characterized in that, include: Fly ash and slag are mixed to obtain a solid waste mixture powder; The phase change medium is melted and added to the solid waste mixture powder, then ultrasonically dispersed to obtain a suspension; A silicon source is dispersed in a solvent, and then a silica coating layer is formed on the surface of the suspension using a sol-gel method to obtain a coated suspension. The coated suspension was freeze-dried to obtain a supercooled phase change material based on thermal power solid waste.

4. The preparation method according to claim 3, characterized in that, The mass ratio of the solid waste mixture powder, the phase change medium and the silicon source is (8-15):(80-90):(8-22); And / or, the melting point of the phase change medium is 80-150°C; And / or, the phase change medium includes at least one of erythritol and sodium sulfate decahydrate; And / or, the silicon source includes at least one of tetraethyl orthosilicate, tetramethoxysilane, and propyl orthosilicate, and may be tetraethyl orthosilicate; And / or, the mass ratio of the fly ash to the slag is (2-4):1, optionally 3:1; And / or, the fly ash has at least one of the following characteristics: (1) In the fly ash, the mass ratio of silicon dioxide to aluminum oxide is greater than 2.5 and less than 4; (2) Loss on ignition is below 5 wt%; (3) The particle size range is below 50 μm, and can be selected as 40-50 μm; And / or, the slag has at least one of the following characteristics: 1) Calcium oxide content is above 35 wt%; 2) Particle size range is below 100μm.

5. The preparation method according to claim 3, characterized in that, The freeze-drying temperature is -50℃ to -30℃, and can be -40℃; And / or, the vacuum degree of the freeze-drying is 1-10 Pa; And / or, the freeze-drying time is 8-16 h, optionally 12 h; And / or, the mass ratio of the silicon source to the solvent is 1:(3-5), optionally 1:4; And / or, the solvent includes at least one of ethanol solution, isopropanol solution, and ethylene glycol dimethyl ether solution, optionally ethanol solution; And / or, the preparation method of the thermal power solid waste-based large supercooling phase change material further includes: Before mixing fly ash and slag, pickling the fly ash and then washing it with water until neutral, and then ball milling it to the first target particle size; And / or, crushing and screening the slag to the second target particle size; Optionally, the first target particle size is below 50 μm, optionally 40-50 μm; the second target particle size is below 100 μm.

6. A double-walled vacuum container, characterized in that, Includes: An inner layer tube, on which at least one trigger unit is installed; An outer shell, the outer shell sleeves the periphery of the inner layer tube, and a sandwich space is formed between the two; the trigger unit is arranged in the sandwich space, and the phase change material is encapsulated in the space other than the trigger unit in the sandwich space. The phase change material is the thermal power solid waste-based large supercooling phase change material as described in claim 1 or 2 or the thermal power solid waste-based large supercooling phase change material prepared by the preparation method as described in any one of claims 3 to 5.

7. The double-layer vacuum container according to claim 6, characterized in that, The inner layer tube is a corrugated aluminum tube, a pure copper tube or a 6063 aluminum alloy tube; And / or, the wall thickness of the inner layer tube is 1.3-1.7 mm; And / or, the thermal conductivity of the inner layer tube is 200-390 W / (m•K), optionally 237 W / (m•K); And / or, the trigger unit is an ultrasonic oscillator, optionally an ultrasonic oscillator with a power density of 45-55 W / m² and a frequency of 20-30 kHz; And / or, when the number of the trigger units is greater than 1, the distance between two adjacent trigger units is 25-35 cm; And / or, an insulating layer is provided on the inner surface of the outer shell, and the sandwich space is formed between the insulating layer and the inner layer tube; And / or, the thickness of the outer shell is 2.5-3.5 mm; And / or, the material of the outer shell is Q235 steel, Q345 steel or 304 stainless steel; And / or, the sandwich space is an annular sandwich space or a "return" shaped sandwich space; And / or, the vacuum degree of the double-layer vacuum container is 1-10 Pa.

8. The double-layer vacuum container according to claim 6, characterized in that, An anti-corrosion coating is provided between the inner surface of the outer shell and the insulating layer; optionally, the anti-corrosion coating is an anti-corrosion coating with a heat resistance temperature greater than 150 °C; And / or, the thickness of the insulating layer is 35-50 mm; And / or, the insulating layer is a fly ash-expanded perlite composite insulating layer, a fly ash-vermiculite composite insulating layer or a slag-aluminum silicate fiber composite insulating layer, optionally a fly ash-expanded perlite composite insulating layer; Optionally, the fly ash content in the fly ash-expanded perlite composite insulation layer is above 40 wt%, and / or the fly ash-expanded perlite composite insulation layer is an insulation layer that has undergone CO2 mineralization treatment at 0.3-0.8 MPa and 1.5-3 h.

9. A cross-seasonal energy storage system, comprising: A heat supply unit for providing heat; Multiple energy storage units are used to receive heat from the heat supply unit; The energy storage unit is a double-layer vacuum container as described in any one of claims 6 to 8; the inlet of the inner tube of the energy storage unit is connected to the heat supply unit; valves are provided between the inner tubes of the multiple energy storage units to control the series or parallel connection of the inner tubes of the multiple energy storage units. A heat exchange module is a heat exchanger connected to a building underfloor heating / air conditioning system. The primary side of the heat exchanger is connected to the inner tube and forms a loop with the inner tube. A first circulation pump is installed on the loop. The secondary side of the heat exchanger is connected to the evaporator side and the condenser side of the heat pump through a three-way valve and a second circulation pump. The condenser side is connected to the building underfloor heating / air conditioning system. The control unit includes a temperature sensor group, a meteorological data receiving module, a PLC controller, and a long short-term memory network (LSTM) thermal demand prediction model, and is equipped with an overcooling trigger algorithm. The temperature sensor group, meteorological data receiving module, and LSM thermal demand prediction model are connected to the input terminal of the PLC controller. The temperature sensor group includes a first temperature sensor, a second temperature sensor, a third temperature sensor, a fourth temperature sensor, and a fifth temperature sensor. The first temperature sensor is connected to the energy storage unit, the second temperature sensor is used to test the ambient temperature, the third temperature sensor is used to test the building's indoor temperature, the fourth sensor is used to test the primary side temperature, and the fifth sensor is used to test the secondary side temperature. The output terminal of the PLC controller is connected to the trigger units of all valves, three-way valves, the first circulating pump, the second circulating pump, the heat pump, and all energy storage units. Optionally, the heat supply unit is a solar collector or an industrial waste heat exchanger; Optionally, the heat exchanger is a plate heat exchanger, and / or the heat exchanger has a thermal efficiency greater than 90%, and the heat exchanger withstands a pressure of 1.0-2.5 MPa; Optionally, the heat pump is an air source heat pump, and the three-way valve is an electric three-way ball valve; Optionally, the first temperature sensor, the fourth temperature sensor, and the fifth temperature sensor are PT100 platinum resistance temperature sensors, and the second temperature sensor and the third temperature sensor are digital temperature sensors. Optionally, the cross-seasonal energy storage system further includes a metering module, which is used to record the stored or released heat energy and to transmit it remotely.

10. A control method for a cross-seasonal energy storage system as described in claim 9, characterized in that, include: The temperature sensor collects the temperature of the phase change material, the ambient temperature, the building's indoor temperature, the temperature of the primary side, and the temperature of the secondary side in real time, and feeds back the temperature information to the PLC controller. The meteorological data collection module acquires climate information for a preset future time period and feeds the climate information back to the PLC controller; the meteorological information includes temperature, humidity, and solar radiation; The long short-term memory network heat demand prediction model predicts heat demand based on the temperature information and the climate information, and feeds back the heat demand information to the PLC controller; the heat demand information includes at least one of the phase change material temperature, building heat load and ambient temperature; The temperature of the phase change material is defined as T. PCM The PLC controller dynamically switches between the following operating modes (1) to (5) based on the thermal demand information: 1) Direct heating mode: When T PCM When the temperature is ≥90℃, the valve is opened to release heat directly. The PLC starts the first circulation pump and the second circulation pump and shuts down the heat pump. The heat output power is ≥30kW. 2) Multiple energy storage units in series mode: When 70℃≤TPCM<90℃, the PLC opens the valve of the inner tube of the energy storage unit, so that the inner tubes of multiple energy storage units are connected in series to release heat in a coordinated manner, with a total heat output power ≥20kW; 3) Heat pump coupling mode: When 40℃≤TPCM<70℃, the heat pump is started to raise the evaporation temperature to 50±2℃, COP≥3.2; 4) Ultrasonic triggering mode: When 20℃≤TPCM<40℃ and the building heat load is >80% of the preset value, the ambient temperature is ≤5℃, and the temperature gradient of the phase change material is >5℃ / cm, the ultrasonic transducer array is activated, and crystallization is induced within 10s; 5) Heat pump direct supply mode: When TPCM<20℃, switch to independent heat pump heating, with a heating temperature ≥45℃.

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