Floor heating structure with phase change material layer and preparation method of floor heating structure

Abstract

The invention discloses a floor heating structure with a phase change material layer and a preparation method of the floor heating structure, and belongs to a floor heating structure, the floor heating structure comprises a base material layer, the phase change material layer, an auxiliary heat conduction layer and a floor surface layer from bottom to top in sequence; a metal heat-conducting net is embedded into the lower part of the base material layer; the phase change material layer comprises the following components in percentage by weight: 53%-58% of methyl laurate, 30%-35% of n-decanol, 5%-8% of nano aluminum oxide, 4%-6% of polyvinyl alcohol and 0.5%-1.5% of carboxymethyl cellulose. Solid-liquid phase change is carried out through the phase change material layer, redundant heat is absorbed, latent heat is released when a heat source is shut down, and therefore frequent starting and stopping of the heat source are reduced, and energy consumption is reduced. According to the multi-layer heat conduction design, through collaborative optimization of the metal heat conduction net and the auxiliary heat conduction layer, the heat efficiency of the floor heating structure is further improved, the heat response time is shortened, the latent heat characteristic of the phase change material is utilized, the heat buffering effect can be achieved in the floor, the heating temperature fluctuation range is reduced, and the heating comfort is improved.

Description

Technical Field

[0001] This invention relates to a floor heating structure, and more specifically, to a floor heating structure with a phase change material layer and its preparation method. Background Technology

[0002] Underfloor heating, as an efficient and comfortable heating method, transfers heat to the room through radiation and convection by laying heat sources (such as hot water pipes or electric heating films) under the floor. It is widely used in residential, commercial, and industrial buildings. Compared to traditional radiator heating, underfloor heating has advantages such as uniform temperature distribution, high thermal comfort, and high space utilization. However, traditional underfloor heating systems have significant limitations, such as low energy efficiency, slow thermal response, and large temperature fluctuations. Especially in low-temperature heating or intermittent heating scenarios, it is difficult to quickly and stably maintain a comfortable indoor temperature (22°C to 26°C), leading to increased energy consumption and a decreased user experience. In existing underfloor heating technologies, some solutions improve energy efficiency by optimizing the heat source layout or adding insulation layers, but these methods are difficult to effectively solve the problems of uneven heat distribution or temperature fluctuations during intermittent heating. Therefore, it is necessary to research and improve the current underfloor heating structure. Summary of the Invention

[0003] One of the objectives of this invention is to address the aforementioned shortcomings by providing a floor heating structure with a phase change material layer and its preparation method. This aims to solve the technical problems of low energy efficiency, slow thermal response, and temperature fluctuations during uneven heat distribution or intermittent heating in similar existing floor heating structures.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: This invention provides a floor heating structure with a phase change material layer. The floor heating structure comprises, from bottom to top, a substrate layer, a phase change material layer, an auxiliary heat conduction layer, and a floor surface layer. A metal heat-conducting mesh is embedded in the lower part of the substrate layer, and the metal heat-conducting mesh is used to contact a heat source. The phase change material layer comprises, by weight percentage: 53%-58% methyl laurate, 30%-35% n-decyl alcohol, 5-8% nano-alumina, 4%-6% polyvinyl alcohol, and 0.5%-1.5% carboxymethyl cellulose. The auxiliary heat conduction layer is a graphene coating vapor-deposited on the phase change material layer. The floor surface layer is a high thermal conductivity ceramic thin plate or engineered wood flooring.

[0005] As a preferred embodiment, a further technical solution is that the substrate layer, phase change material layer, auxiliary heat conduction layer, and floor surface layer are further covered with a sealing and protective layer, wherein the sealing and protective layer is a modified polyethylene film, and the modified polyethylene film is seamlessly heat-fused to the substrate layer and the floor surface layer.

[0006] A further technical solution is that a heat source interface groove is provided at the lower part of the substrate layer, the metal heat-conducting mesh is close to the heat source interface groove, and the heat source interface groove is used to embed the heat source.

[0007] Another aspect of the present invention provides a method for preparing the above-mentioned floor heating structure, the method comprising the following steps: Step A: Prepare the phase change material layer. Weigh out a certain amount of methyl laurate, n-decyl alcohol, nano alumina, polyvinyl alcohol and carboxymethyl cellulose. Then place methyl laurate and n-decyl alcohol in a sealed reaction vessel under nitrogen protection. After stirring at a temperature of 60-70°C, a eutectic mixture is obtained.

[0008] Nano-alumina, polyvinyl alcohol, and carboxymethyl cellulose were added to the eutectic mixture, and then ultrasonically dispersed to obtain a homogeneous phase change material.

[0009] The homogeneous phase change material is added to 4-6 times its weight of deionized water, and then an emulsifier accounting for 1%-1.5% of the weight of the phase change material is added and stirred. During stirring, a polyurea prepolymer is slowly added dropwise, the polyurea prepolymer accounting for 15%-20% of the weight of the phase change material. After stirring and reacting, a polyurea shell material is obtained that encapsulates the homogeneous phase change material microcapsules. After centrifugation, filtration, washing and drying, it is ready for use.

[0010] The polyurea shell material encapsulating uniform phase change material microcapsules is stirred and dispersed in an aqueous polyurethane base liquid. After filtration through a sieve, it is sprayed onto the upper part of a preheated substrate layer using a high-pressure spraying device to obtain a phase change material layer. The thickness of the phase change material is 2.6-4.9 mm. The solid content in the aqueous polyurethane base liquid is 30%-35% of its total weight. The substrate layer is a high-density fiberboard.

[0011] Step B: Prepare an auxiliary heat conduction layer by depositing a graphene coating on the surface of the phase change material layer by vapor deposition. The thickness of the graphene coating is 0.2-0.4 mm.

[0012] Step C: Prepare the floor surface layer by hot-pressing a high thermal conductivity ceramic thin plate or engineered wood flooring onto the auxiliary heat conduction layer, and merging it with the phase change material layer and the substrate layer into one unit.

[0013] As a preferred embodiment, a further technical solution is: the method further includes processing a heat source interface groove in the lower part of the substrate layer, wherein the wall of the heat source interface groove is coated with thermally conductive silicone grease.

[0014] A further technical solution is that the method further includes embedding a metal heat-conducting mesh in the lower part of the substrate, and the metal heat-conducting mesh is hot-pressed to the bottom of the heat source interface groove by a hot press.

[0015] A further technical solution is that the method further includes heat-sealing the modified polyethylene film to the edges of the substrate layer and the floor surface layer by means of heat-sealing.

[0016] Compared with the prior art, one of the beneficial effects of the present invention is that: through the solid-liquid phase change of the phase change material layer, excess heat is absorbed and latent heat is released when the heat source is shut down, thereby reducing the frequent start-up and shutdown of the heat source and reducing energy consumption; the multi-layer heat conduction design further improves the thermal efficiency of the floor heating structure and shortens the thermal response time by co-optimizing the metal heat conduction mesh and the auxiliary heat conduction layer; and by utilizing the latent heat characteristics of the phase change material, it can play a role in thermal buffering in the floor, thereby reducing the temperature fluctuation range when the heat source is started and stopped or during intermittent heating, and improving the comfort of heating. Attached Figure Description

[0017] Figure 1 This is a schematic diagram illustrating a floor heating structure according to an embodiment of the present invention.

[0018] Figure 2 This is a statistical diagram illustrating the thermal buffering effect of a phase change material layer in one embodiment of the present invention.

[0019] Figure 3 This is a schematic diagram illustrating the microencapsulation structure of a phase change material in one embodiment of the present invention. Detailed Implementation

[0020] This invention addresses the technical deficiencies mentioned in the background section by proposing an innovative low-temperature phase change layer structure. Through the use of composite phase change materials, microencapsulation technology, and multi-layer thermal conductivity optimization design, the structure is embedded in the floor structure, significantly improving the energy efficiency, temperature stability, and durability of the floor heating system, and providing an efficient and environmentally friendly solution for low-temperature heating scenarios.

[0021] Specifically, this invention embeds a compounded low-temperature phase change material into the floor structure, achieving efficient thermal buffering and stable heating at low temperatures of 20°C to 30°C. Utilizing the heat absorption and release properties of the phase change material, the floor temperature is dynamically controlled, solving problems such as low energy efficiency, large temperature fluctuations, and slow thermal response in traditional floor heating systems. This significantly improves the energy utilization efficiency and indoor thermal comfort of the underfloor heating system. It also facilitates heat management and is suitable for intermittent heating or scenarios with large ambient temperature fluctuations in residential buildings, commercial buildings, and industrial sites.

[0022] According to one embodiment of the present invention, such as Figure 1As shown, in this embodiment, the floor heating structure with a phase change material layer consists of a substrate layer, a phase change material layer, an auxiliary heat conduction layer, and a floor surface layer from bottom to top. A metal heat conduction mesh is embedded in the lower part of the substrate layer, which is used to contact the heat source. More importantly, the aforementioned phase change material layer includes, by weight percentage, 53%-58% methyl laurate, 30%-35% n-decyl alcohol, 5-8% nano-alumina, 4%-6% polyvinyl alcohol, and 0.5%-1.5% carboxymethyl cellulose. The auxiliary heat conduction layer is a graphene coating vapor-deposited on the phase change material layer. The floor surface layer is a high thermal conductivity ceramic thin plate or engineered wood flooring.

[0023] The aforementioned substrate layer is high-density fiberboard or solid wood composite board, with a thickness of 8 mm to 12 mm and a thermal conductivity of 0.16 W / m·K to 0.22 W / m·K, providing excellent mechanical strength, thermal conductivity and moisture resistance.

[0024] The main components of the aforementioned phase change material layer are methyl lauryl acid and n-decanol, which form a eutectic mixture through esterification. The phase change temperature ranges from 22.3℃ to 27.7℃, and the latent heat capacity ranges from 198 J / g to 238 J / g (measured by differential scanning calorimetry (DSC) at a scan rate of 4℃ / min with an accuracy of ±0.1℃). The thermal conductivity enhancer is nano-alumina (Al₂O₃, particle size 35-50 nm, thermal conductivity 32 W / m·K), whose surface is modified with silane coupling agent KH-550 (1.5 wt%) to enhance interfacial bonding, increasing the overall thermal conductivity from 0.18 W / m·K to 0.92 W / m·K. The stabilizers are polyvinyl alcohol (PVA, molecular weight 22000, solubility optimized) and carboxymethyl cellulose (CMC, viscosity 600 mPa·s), forming a dual stabilizing system to prevent delamination or leakage during the solid-liquid phase change process.

[0025] The aforementioned auxiliary heat conduction layer is a 0.3 mm graphene coating deposited on the surface of the phase change material layer, achieved using a chemical vapor deposition (CVD) process.

[0026] The aforementioned floor surface layer is bonded together with the auxiliary heat conduction layer through a hot-pressing composite process.

[0027] In this embodiment, preferably, to prevent leakage from the microcapsule structure of the phase change material layer, a sealing protective layer is also wrapped around the outside of the substrate layer, the phase change material layer, the auxiliary heat conduction layer, and the floor surface layer. The sealing protective layer is a modified polyethylene film, which is seamlessly heat-fused to the substrate layer and the floor surface layer. Simultaneously, to facilitate heat transfer, a heat source interface groove can be designed at the bottom of the substrate layer, with the aforementioned metal heat-conducting mesh positioned close to the heat source interface groove. The heat source interface groove is used to embed a heat source, such as a hot water pipe or an electric heating film.

[0028] Based on the above embodiments of the present invention, the manufacturing process of the floor heating mechanism is as follows: Step 1: Prepare the phase change material layer. Weigh out a certain amount of methyl laurate, n-decyl alcohol, nano alumina, polyvinyl alcohol and carboxymethyl cellulose. Then place methyl laurate and n-decyl alcohol in a sealed reaction vessel under nitrogen protection. After stirring at a temperature of 60-70℃, a eutectic mixture is obtained.

[0029] Step 2: Add nano-alumina, polyvinyl alcohol and carboxymethyl cellulose to the eutectic mixture, and then perform ultrasonic dispersion to obtain a homogeneous phase change material.

[0030] Step 3: Add the homogeneous phase change material to 4-6 times its weight of deionized water, then add an emulsifier accounting for 1%-1.5% of the weight of the phase change material and stir. While stirring, slowly add polyurea prepolymer, which accounts for 15%-20% of the weight of the phase change material. After stirring and reacting, a polyurea shell material is obtained that encapsulates the homogeneous phase change material microcapsules. After centrifugation, filtration, washing and drying, it is ready for use.

[0031] Step 4: The polyurea shell material coated with uniform phase change material microcapsules is stirred and dispersed in an aqueous polyurethane base liquid. After filtration through a sieve, it is sprayed onto the preheated substrate layer using a high-pressure spraying device to obtain a phase change material layer. The thickness of the phase change material is 2.6-4.9 mm. The solid content in the aqueous polyurethane base liquid is 30%-35% of its total weight. The aforementioned substrate layer is a high-density fiberboard.

[0032] Step 5: Prepare an auxiliary heat conduction layer by depositing a graphene coating on the surface of the phase change material layer by vapor deposition. The thickness of the graphene coating is 0.2-0.4 mm.

[0033] Step 6: Prepare the floor surface layer by hot-pressing a high thermal conductivity ceramic thin plate or engineered wood flooring onto the auxiliary heat conduction layer, integrating it with the phase change material layer and the substrate layer. Then, hot-press encapsulation is used to thermally fuse the modified polyethylene film with the edges of the substrate layer and the floor surface layer.

[0034] Furthermore, a heat source interface groove is processed at the lower part of the substrate layer, and the inner wall of the heat source interface groove is coated with thermally conductive silicone grease. A metal thermally conductive mesh is embedded at the lower part of the substrate, and the metal thermally conductive mesh is hot-pressed to the bottom of the heat source interface groove by a hot press.

[0035] In this invention, in addition to phase change materials, a multi-layered thermal conductivity optimization design is employed to improve heat transfer efficiency. An efficient heat transfer path is constructed using an aluminum metallic heat-conducting mesh, a graphene-assisted heat-conducting layer, and a far-infrared radiation coating. This multi-layered design shortens the thermal response time and improves thermal efficiency.

[0036] The microencapsulated phase change material was uniformly embedded into the floor structure using a process involving plasma etching (surface roughness Ra 2.8 μm, surface energy 52 mN / m), three high-pressure sprayings (thickness deviation ≤ 0.07 mm), negative pressure defoaming (0.025 MPa), and a modified polyethylene (PE) sealing protective layer (0.7 mm thick, containing UV stabilizers and antioxidants). Figure 1 The spraying process incorporates a crosslinking agent (0.5 wt% isocyanate), increasing coating hardness by 10% and peel strength to 2.3 MPa. A PE film combined with a nano-hydrophobic coating (contact angle ≥125°) is prepared via plasma-enhanced chemical vapor deposition (PECVD), exhibiting excellent moisture resistance and anti-aging properties (no performance degradation after 2000 hours at 95℃ and 90% humidity). Microencapsulated structure ( Figure 3 To prevent leakage, the floor structure has undergone cyclic loading (0.65 MPa, 2000 cycles) and thermal cycling (15℃ to 35℃, 2000 cycles) tests, with a lifespan of ≥20 years. This provides a long-term, stable solution for underfloor heating.

[0037] This invention features a structure adaptable to both hydronic heating (hot water pipe flow rate 0.3 m³ / h) and electric heating (electric heating film 220 V, 200 W / m²) systems. The standardized heat source interface groove is CNC machined (roughness Ra 0.8 micrometers) and optimized with thermally conductive silicone grease (reducing thermal resistance by 20%). Adjusting the phase change material ratio (methyl laurate increased to 58 wt%) expands the phase change temperature to 18°C ​​to 32°C, meeting the needs of cold to warm climates. An integrated intelligent temperature control module (thermocouple: Omega KHSS-116U, PID controller: Siemens SIMATIC S7-1200, accuracy ±0.3°C) dynamically adjusts the heat source for greater energy efficiency. Furthermore, its modular design (600 mm × 600 mm floor, splicing tolerance ±0.05 mm) facilitates installation and maintenance, and it can be expanded to walls or roofs in the future for passive building energy conservation.

[0038] Based on the above embodiments of the present invention, the inventors also provide some preferred embodiments in experiments.

[0039] Application Example 1: Preparation of Standard Floor Structure Floor substrate preparation. High-density fiberboard (HDF, density 920 kg / m³, dimensions 1200 mm × 600 mm × 10 mm, compressive strength 32 MPa, water absorption swelling rate ≤8%, thermal conductivity 0.18 W / m·K) was selected. The upper surface of the substrate was treated with low-temperature plasma etching (equipment: PlasmaTech-100, power 130W, argon / oxygen mixture ratio 3:1, pressure 0.07 mbar, treatment time 7 minutes), increasing the surface roughness (Ra) from 0.4 μm to 2.8 μm, the surface energy from 28 mN / m to 52 mN / m, and the contact angle from 80° to 45° (contact angle meter: Krüss DSA100). After etching, ultrasonic cleaning was performed (40 kHz, 6 minutes, deionized water containing 0.1 wt% sodium dodecyl sulfate, equipment: Elmasonic P), and the surface impurity content was <0.1% (SEM, model: JEOL JSM-7800F). An aluminum heat-conducting mesh (3.5 mm × 3.5 mm mesh size, 0.7 mm thickness, thermal conductivity 210 W / m·K, material: 6061 aluminum alloy) is embedded 1 mm below the substrate and fixed using a hot press (model: HP-500, pressure 0.45 MPa, 135℃, 7 minutes). The edges of the heat-conducting mesh are laser-welded (power 500 W, speed 0.5 m / s, equipment: Trumpf TruLaser5030). Thermal grease (0.12 mm thickness, thermal conductivity 6 W / m·K, model: Dow Corning TC-5026, coating equipment: Bürkle RCL 1300) is applied to the contact surface between the heat-conducting mesh and the heat source to reduce contact thermal resistance.

[0040] Preparation of phase change materials. The composition ratio is as follows: methyl lauryl ester (53wt%), n-decyl alcohol (35wt%), nano-alumina (6wt%, particle size 35 nm, surface modified with KH-550 silane coupling agent, modifier dosage 1.5wt%), polyvinyl alcohol (PVA, 5wt%, molecular weight 22,000, hydroxyl value ≥98%), and carboxymethyl cellulose (CMC, 1wt%, viscosity 600 mPa·s, degree of substitution 0.9).

[0041] The preparation process is as follows: In a nitrogen-protected reactor (model: RR-500L, volume: 500L, pressure: 0.1 MPa), 53 kg of methyl lauryl ester and 35 kg of n-decanol were added, and the mixture was stirred at 63℃ and 650 rpm for 3.2 hours (stirrer: IKA RW 20) to form a eutectic mixture. Modified nano-alumina (6 kg), PVA (5 kg), and CMC (1 kg) were then added, and the mixture was ultrasonically dispersed (equipment: Sonicator-4000, power: 400 W, frequency: 38 kHz, duration: 50 minutes, temperature control: 60±2℃) to form a homogeneous phase change material with a viscosity of 800 mPa·s.

[0042] Testing: DSC (model: TA Q200, scan rate 4℃ / min, nitrogen atmosphere) determined the phase transition temperature from 22.3℃ to 27.7℃, latent heat capacity from 198 J / g to 238 J / g, melting enthalpy ΔH_m = 200 J / g, and crystallization enthalpy ΔH_c = 198 J / g; TGA (model: Netzsch STA 449, 10℃ / min, air atmosphere) confirmed the thermal decomposition temperature at 185℃ with a mass loss of 5%; FTIR (model: Nicolet iS50, 1720 cm⁻¹ ester peak, 3400 cm⁻¹ hydroxyl peak) verified the eutectic structure; XRD (model: Bruker D8, Cu Kα radiation, 2θ = 10°-80°) confirmed that the nano-alumina was free of agglomeration.

[0043] Microencapsulation of phase change materials. At 53°C and pH=4.2 (adjusted with 0.1M HCl, pH meter: Mettler Toledo Seven Excellence), 100 kg of phase change material was dispersed in 500 kg of deionized water (solid-liquid ratio 1:5), and emulsifier (0.7 kg sodium dodecyl sulfate, purity ≥99%) was added. The mixture was stirred at 1200 rpm for 12 minutes (emulsifier: IKAT50, droplet diameter 7-50 μm, microscope: Olympus BX53). Polyurea prepolymer (isocyanate MDI to amine monomer EDA molar ratio 1:1.2, 20 kg, dropping rate 0.5 kg / min) was slowly added dropwise at 650 rpm for 5 hours (reactor: RR-500L) to generate polyurea shells (shell wall thickness 0.3-0.8 μm, microcapsule diameter 7-65 μm). Centrifugal filtration (6500 rpm, 15 minutes, centrifuge: Beckman J-26XP), washed 5 times with deionized water (500L each time), vacuum dried (60℃, 16 hours, dryer: VFD-200), with a packaging rate of 97% (thermogravimetric analysis). SEM (model: JEOL JSM-7800F) confirmed the shell was intact, and laser particle size analyzer (model: Malvern Mastersizer3000) measured D50≈30 μm, with a particle size distribution standard deviation of ±5 μm.

[0044] Phase change material embedding treatment. Microcapsules were dispersed in an aqueous polyurethane base liquid (solid content 33%, viscosity 650 mPa·s, microcapsules 43wt%, containing 0.5wt% isocyanate crosslinking agent HDI, model: Bayer Desmodur N3300), stirred at 900 rpm for 25 minutes (mixer: IKA Eurostar 60), and filtered through a 200-mesh sieve (filter: ErtelAlsop 200 Mathematical; filter: ErtelAlsop 200-mesh sieve) to remove large particles (sieve: Retsch AS 200). High-pressure spraying equipment (model: Graco XP70, pressure 0.38 MPa, nozzle diameter 0.35 mm, flow rate 0.5 L / min) was used to coat the preheated substrate (42℃, preheating oven: Memmert) at a speed of 0.15 m / min. The UF500 coating, with a thickness of 2.4 mm to 4.9 mm, was applied in three coats (1.5 mm to 1.6 mm each, with 12-minute intervals for natural drying, ambient humidity ≤60%). It was dried in an 85°C infrared oven (650W / m², Heraeus IR-500) for 40 minutes, followed by negative pressure adsorption (0.025 MPa, 3 minutes, Busch R5 KB0016) to remove micro-bubbles. A laser rangefinder (Leica Disto D8) was used to check the thickness deviation (≤0.07 mm), and the coating hardness (HB, Elcometer 501, ASTM D3363) and tensile test (Instron 5982, ASTM D903) confirmed a peel strength of 2.3 MPa. After spraying, the coating was inspected under a microscope (Olympus BX53) for cracks and pores.

[0045] Auxiliary thermal conductivity layer preparation. A 0.3 mm graphene coating (thermal conductivity 2300 W / m·K, density 1.9 g / cm³) was deposited on the surface of the phase change material layer using chemical vapor deposition (CVD) (equipment: Aixtron Black Magic, 930 °C, methane 16 sccm, hydrogen 130 sccm, 40 min, nickel catalyst layer 60 nm, magnetron sputtering equipment: AJA Orion 5). Post-deposition plasma cleaning (oxygen / argon ratio 1:1, 70 W, 4 min, equipment: DienerNano) removed carbon impurities (residual carbon <0.5%). XPS (Thermo Fisher ESCALAB 250Xi, C1s peak 284.8 eV) verified graphene purity ≥99%, and Raman spectroscopy (Horiba LabRAM HR, 532 nm laser, I²D / I_G≈2, G peak 1580 cm⁻¹) confirmed high-quality monolayer graphene. The graphene coating reduces thermal resistance by 42% (thermal resistance tester: Netzsch LFA 467), and shows no performance change in corrosion resistance tests (pH 3-11, 168 hours, equipment: Q-LabQ-Fog), preventing microcapsule leakage.

[0046] Floor surface preparation. High thermal conductivity ceramic thin plates (thermal conductivity 2.0 W / m·K, dimensions 1200 mm × 600 mm × 2.5 mm, compressive strength 120 MPa, Mohs hardness 7, material: alumina-based ceramic) or engineered wood flooring (thickness 3.5 mm, abrasion resistance grade AC5, surface alumina coating, abrasion resistance ≥6000 revolutions, test standard: EN 13329) are selected. Modified polyurethane adhesive (130 g / m², shear strength 2.0 MPa, containing 1.5 wt% silane coupling agent KH-570, model: Henkel Loctite 330) is applied uniformly using a precision roller coating machine (model: Bürkle RCL 1300, speed 0.07 m / s, coating thickness uniformity ±4 micrometers). Hot pressing (pressure 0.65 MPa, 130℃, 15 minutes, hot press: Wemhöner KT-V-1200), vacuum degassing (0.015 MPa, 6 minutes, equipment: Busch R5 RA0100), bubble rate <0.1% (ultrasonic detector: Olympus OmniScan SX). A far-infrared radiation coating (15 μm thickness, emissivity 0.94, containing zirconium oxide and silica microparticles, 1 μm particle size, 3:1 ratio) is sprayed onto the surface via high-pressure spraying (model: Wagner Control Pro 350, pressure 0.28 MPa, nozzle 0.3 mm, flow rate 0.4 L / min), dried at 95℃ for 25 minutes (drying oven: Memmert UF500), resulting in an 18% increase in radiation efficiency (infrared radiometer: Fluke 568 IR). Surface flatness deviation ≤0.05 mm.

[0047] A sealing and protective layer was prepared. A 0.7 mm thick modified polyethylene (PE) film (containing 6 wt% UV stabilizer BASF Tinuvin 326, 2 wt% antioxidant Irganox 1010, tensile strength 25 MPa, test standard: ASTM D882) was used around the perimeter of the floor structure. It was then heat-sealed (pressure 0.3 MPa, 160°C, 5 minutes, hot press: Langzauner LZT-OK-100) to the substrate and surface layer edges, achieving a bond strength of 1.8 MPa, peel test: ASTM D3330. A nano-hydrophobic coating (silica-based, 50 nm thick, contact angle 125°, contact angle meter: Krüss DSA100) was applied to the film surface using plasma-enhanced chemical vapor deposition (PECVD, equipment: Oxford PlasmaLab 100, power 50 W, 10 minutes, precursor: hexamethyldisiloxane, flow rate 10 sccm). Air tightness test (95℃, 90% humidity, 2000 hours, environmental chamber: Weiss WK3-1000) confirmed no moisture penetration, no change in microcapsule structure (SEM detection), and no decrease in latent heat and thermal conductivity of phase change material.

[0048] Fabricate the heat source interface groove. A standardized heat source interface groove (22 mm width, 6 mm depth, tolerance ±0.1 mm, CNC machine tool: DMG MORI CMX 600V, surface roughness Ra 0.8 μm, roughness meter: Mitutoyo SJ-410) is machined on the bottom of the substrate. The groove is compatible with hot water pipes (16 mm outer diameter, 2 mm wall thickness, material: PEX-AL-PEX, pressure resistance 1.0 MPa) or electric heating film (0.6 mm thickness, power 200 W / m², model: Warmup DCM-Pro). Thermal grease (0.15 mm thickness, thermal conductivity 7 W / m·K, model: Shin-Etsu G-751, applicator: Nordson ProBlue 4) is applied to the inner wall of the groove to reduce contact thermal resistance by 20% (thermal resistance tester: Netzsch LFA 467). The groove edges are filled with high-temperature resistant silicone sealant (temperature resistance -50℃ to 180℃, tensile strength 2.5 MPa, model: Dow Corning 732) with a sealing width of 2 mm to prevent heat loss and moisture intrusion (air tightness test: 95℃, 90% humidity, 2000 hours). A thermocouple sensor (K-type, accuracy ±0.2℃, model: Omega KHSS-116U, response time 0.5 seconds) is pre-embedded inside the groove and fixed with thermally conductive adhesive (thermal conductivity 1.5 W / m·K, model: 3M TC-2810).

[0049] Application Example 2: Extending the Phase Transition Temperature Range The phase change material ratio was adjusted as follows: methyl laurate 58wt%, n-decanol 30wt%, nano-alumina 6wt%, polyvinyl alcohol 5wt%, and carboxymethyl cellulose 1wt%. The preparation process was the same as in Application Example 1. DSC measurements showed a phase change temperature of 18℃ to 32℃, a latent heat capacity of 195 J / g, and a thermal conductivity of 0.90 W / m·K (Hot Disk TPS 2500S). The embedding process and structure were the same as in Example 1. Tests showed a temperature fluctuation of ±0.7℃ and an 18% reduction in energy consumption (heat source power 2.5 kW / m², ambient temperature 15℃), making it suitable for warm climates (e.g., areas with an average annual temperature of 15℃ to 25℃). Operational testing (laboratory area 20m², electrothermal film 200W / m²) showed a thermal response time of 14 minutes and a temperature maintenance time of 6 hours. Figure 2 As shown.

[0050] Application Example 3: Intelligent Temperature Control Integration Based on the structure of Example 1, an intelligent temperature control module (including a K-type thermocouple, accuracy ±0.2℃, model: Omega KHSS-116U; PID controller, model: Siemens SIMATIC S7-1200, control cycle 0.1 seconds) is integrated. The thermocouple is fixed to the interface slot with thermally conductive adhesive (1.5 W / m·K, 3M TC-2810) to monitor the heat source temperature (range 10℃ to 50℃). The controller is connected to a hot water valve (model: Danfoss AVQM, flow rate 0.3 m³ / h) or an electric heating film power supply (220V, 200 W / m²), and dynamically adjusts the output according to the floor temperature (target 25℃) (adjustment accuracy ±0.3℃). Data is transmitted to the host computer via an RS485 interface (software: LabVIEW 2023, sampling rate 1 Hz). Test results (laboratory area 20m², ambient temperature 10℃): 12% energy saving (electricity meter: Schneider PM3250, energy consumption reduced by 0.4 kWh / m²), temperature fluctuation ±0.5℃ (thermocouple data), response time 12.5 minutes, details as follows... Figure 2 As shown.

[0051] In addition to the above, it should be noted that the terms "one embodiment," "another embodiment," and "embodiment" used in this specification refer to specific features, structures, or characteristics described in connection with that embodiment, which are included in at least one embodiment described in the general description of this application. The appearance of the same expression in multiple places in the specification does not necessarily refer to the same embodiment. Furthermore, when a specific feature, structure, or characteristic is described in connection with any embodiment, the intention is to suggest that implementing such a feature, structure, or characteristic in conjunction with other embodiments also falls within the scope of this invention.

[0052] Although the invention has been described herein with reference to several illustrative embodiments, it should be understood that many other modifications and implementations can be devised by those skilled in the art, which will fall within the scope and spirit of the principles disclosed herein. More specifically, various variations and modifications can be made to the components and / or layout of the subject matter arrangement within the scope of the disclosure, drawings, and claims. Besides variations and modifications to the components and / or layout, other uses will be apparent to those skilled in the art.

Claims

1. A floor heating structure with a phase change material layer, characterized in that: The floor heating structure consists of, from bottom to top, a substrate layer, a phase change material layer, an auxiliary heat conduction layer, and a floor surface layer; A metal heat-conducting mesh is embedded in the lower part of the substrate layer, and the metal heat-conducting mesh is used to contact the heat source; The phase change material layer comprises, by weight percentage: 53%-58% methyl lauryl ester, 30%-35% n-decyl alcohol, 5-8% nano-alumina, 4%-6% polyvinyl alcohol, and 0.5%-1.5% carboxymethyl cellulose; The auxiliary heat conduction layer is a graphene coating vapor-deposited on the phase change material layer; The floor surface layer is a high thermal conductivity ceramic thin plate or engineered wood flooring.

2. The floor heating structure with a phase change material layer according to claim 1, characterized in that: The substrate layer, phase change material layer, auxiliary heat conduction layer, and floor surface layer are further covered with a sealing and protective layer, which is a modified polyethylene film. The modified polyethylene film is seamlessly heat-fused to the substrate layer and floor surface layer.

3. The floor heating structure with a phase change material layer according to claim 1, characterized in that: The lower part of the substrate layer is also provided with a heat source interface groove, and the metal heat-conducting mesh is close to the heat source interface groove, which is used to embed the heat source.

4. A method for preparing a floor heating structure according to any one of claims 1-3, characterized in that... The method includes the following steps: To prepare a phase change material layer, weigh out a certain amount of methyl laurate, n-decyl alcohol, nano-alumina, polyvinyl alcohol and carboxymethyl cellulose, then place methyl laurate and n-decyl alcohol in a sealed reaction vessel under nitrogen protection, maintain the temperature at 60-70℃ and stir to obtain a eutectic mixture. Nano-alumina, polyvinyl alcohol, and carboxymethyl cellulose were added to the eutectic mixture, and then ultrasonically dispersed to obtain a homogeneous phase change material. Add the homogeneous phase change material to 4-6 times its weight of deionized water, then add an emulsifier accounting for 1%-1.5% of the weight of the phase change material and stir. While stirring, slowly add polyurea prepolymer, which accounts for 15%-20% of the weight of the phase change material. After stirring and reacting, a polyurea shell material is obtained that encapsulates the homogeneous phase change material microcapsules. After centrifugation, filtration, washing and drying, it is ready for use. The polyurea shell material encapsulating uniform phase change material microcapsules is stirred and dispersed in an aqueous polyurethane base liquid. After filtration through a sieve, it is sprayed onto the preheated substrate layer using a high-pressure spraying device to obtain a phase change material layer with a thickness of 2.6-4.9 mm. The solid content in the aqueous polyurethane base liquid is 30%-35% of its total weight. The substrate layer is high-density fiberboard; An auxiliary heat-conducting layer is prepared by depositing a graphene coating on the surface of the phase change material layer by vapor deposition, wherein the thickness of the graphene coating is 0.2-0.4 mm. To prepare the floor surface layer, a high thermal conductivity ceramic thin plate or engineered wood flooring is hot-pressed onto the auxiliary heat conduction layer, and then integrated with the phase change material layer and the substrate layer.

5. The method for preparing the floor heating structure according to claim 1, characterized in that... The method further includes processing a heat source interface groove in the lower part of the substrate layer, wherein the groove wall is coated with thermally conductive silicone grease.

6. The method for preparing the floor heating structure according to claim 1 or 5, characterized in that... The method further includes embedding a metal heat-conducting mesh in the lower part of the substrate, wherein the metal heat-conducting mesh is hot-pressed to the bottom of the heat source interface groove by a hot press.

7. The method for preparing the floor heating structure according to claim 6, characterized in that... The method also includes heat-sealing the modified polyethylene film to the edges of the substrate layer and the floor surface layer by means of heat-sealing.

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