High-heat-conductivity floor heating spiral pipe based on graphene

Abstract

The invention discloses a high-heat-conductivity floor heating spiral pipe based on graphene, and belongs to the field of floor heating pipes. Comprising a pipe body, a plurality of protruding structures and groove structures are arranged on the outer wall of the pipe body, and the protruding structures and the groove structures are arranged alternately. According to the floor heating spiral pipe, a PERT material serves as a base pipe, and in the raw material preparation process of the base pipe, a graphene material is added according to a specific proportion. The graphene is uniformly dispersed in a PERT matrix through an advanced mixing process to form a stable composite material system, so that the PERT-based tube is endowed with excellent high heat-conducting property, and compared with a traditional PERT material, the heat conductivity coefficient of the PERT-based tube is remarkably improved. During construction, the spiral pipe is designed and laid according to a floor heating system, the spiral concave-convex outer wall of the spiral pipe is in contact with a cement filling layer, the occlusion degree with cement is increased through the concave-convex structure, and the compactness is improved.

Description

Technical Field

[0001] This invention relates to the field of underfloor heating pipes, and particularly to an underfloor heating spiral pipe based on graphene's high thermal conductivity. Background Technology

[0002] Underfloor heating pipes are the core component of an underfloor heating system, primarily used to transport hot water in low-temperature hot water radiant floor heating systems. Common pipe materials include PEX (cross-linked polyethylene), PERT (high-temperature resistant polyethylene), PB (polybutene), and aluminum-plastic composite pipes. PEX pipes are widely used due to their high-temperature resistance, pressure resistance, and flexibility, while PERT pipes are characterized by easy processing and strong low-temperature impact resistance. Underfloor heating pipes are typically laid in coils within the insulation layer beneath the floor, distributing heat evenly throughout the room through circulating hot water. The design must consider pipe diameter (commonly 16-20mm), laying spacing (usually 150-300mm), and loop length (recommended not to exceed 120 meters) to ensure thermal efficiency and prevent excessive system resistance. High-quality underfloor heating pipes should possess characteristics such as corrosion resistance, oxygen permeability resistance, and long lifespan (up to 50 years). During installation, care must be taken to ensure the pipes are seamless, avoid scratches, and perform pressure tests as required. Different materials and brands of underfloor heating pipes vary in thermal conductivity, expansion rate, and price, and the selection should be based on specific heating needs and environmental conditions.

[0003] Existing PE-RT underfloor heating pipes are mostly smooth pipe structures. When their outer walls come into contact with cement, there is a problem of small contact surface and limited heat conduction area, which makes it difficult to meet the heat transfer efficiency requirements for high-efficiency heating and affects the overall heating effect of the underfloor heating system. Summary of the Invention

[0004] This invention provides a graphene-based high thermal conductivity spiral pipe for underfloor heating, which can solve the problems of small contact surface and limited heat conduction area when the existing underfloor heating pipes are in contact with cement, resulting in heat transfer efficiency that cannot meet the demand for efficient heating and affecting the overall heating effect of the underfloor heating system.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A graphene-based high thermal conductivity spiral pipe for underfloor heating includes a pipe body, on the outer wall of which are provided several protruding structures and groove structures, the protruding structures and the groove structures being alternately arranged.

[0007] In one aspect of the present invention, the interior of the tube is roughened.

[0008] In one embodiment of the present invention, both the protruding structure and the groove structure are arranged around the axis of the tube body.

[0009] In one embodiment of the present invention, the protruding structure and the groove structure are spirally distributed on the outer wall of the tube.

[0010] In one embodiment of the present invention, the distance between two adjacent protrusions is 3 mm.

[0011] In one aspect of the present invention: the material of the tube body comprises, by weight percentage: 70%-85% PERT resin, 10%-20% graphene material, 2%-5% dispersant, 0.2%-1% antioxidant, 0.1%-0.5% light stabilizer and 0.3%-1% lubricant.

[0012] In one aspect of the present invention, the material of the tube body further includes 5%-10% by weight of nano-montmorillonite or nano-silica.

[0013] In one embodiment of the present invention: the tube body is formed by extrusion molding using a single screw extruder, wherein the length-to-diameter ratio of the single screw extruder is 38-52:1, the main power is 75-132kW, and the extrusion rate is 200-500kg / h.

[0014] In one aspect of the present invention: the extrusion temperature of the single screw extruder is: zone 1 temperature is 180-200℃, zone 2 temperature is 200-220℃, zone 3 temperature is 220-230℃, zone 4 temperature is 230-240℃, and the die temperature is 220-235℃.

[0015] In one aspect of the present invention: the screw speed of the single screw extruder is 20-40 rpm, and the traction speed is 1-5 m / min.

[0016] According to the present invention, a graphene-based high thermal conductivity underfloor heating spiral pipe has at least one of the following technical advantages:

[0017] 1. Significantly improved thermal conductivity: By adding graphene to the PERT base pipe, the thermal conductivity of the pipe body is enhanced from the material itself. Combined with the significantly increased heat conduction area due to the spiral concave-convex structure of the outer wall, and the promoting effect of the micro-rough structure of the inner wall on heat exchange inside the pipe, the overall heat transfer efficiency of the spiral underfloor heating pipe of this application can be improved by more than 35% compared with traditional underfloor heating pipes. It can bring the indoor temperature to the set temperature in a shorter time and effectively improve the heating effect.

[0018] 2. High Stability and Reliability: The spiral concave-convex structure forms a tight mechanical interlock with the cement, similar to a mortise and tenon joint, ensuring a firm bond between the underfloor heating pipe and the cement filling layer. Experimental testing shows that under long-term thermal expansion and contraction cycles, the bonding strength between the underfloor heating pipe and cement in this application is 35% higher than that of traditional underfloor heating pipes. This effectively avoids common problems such as hollowing and detachment, ensuring stable operation of the underfloor heating system for up to 50 years. It significantly reduces maintenance costs and user inconvenience caused by poor contact, such as localized insufficient heating and system failures.

[0019] 3. Outstanding energy-saving and consumption-reducing effects: Thanks to its high thermal conductivity and optimized heat transfer path, the spiral underfloor heating pipe of this application can effectively reduce the operating energy consumption of the underfloor heating system. Under the same heating demand, compared with traditional underfloor heating systems, it can save 1.5 times the energy consumption, reducing users' heating costs and demonstrating significant economic and social benefits.

[0020] 4. Wide range of applications: Since the size and specifications of the spiral concave-convex structure can be flexibly adjusted according to the actual needs of different underfloor heating projects, whether it is the large-area underfloor heating installation in large commercial buildings or the personalized heating design of small residences, the spiral underfloor heating pipe of this application can meet the requirements of various construction scenarios for contact surface and thermal conductivity through reasonable design of structural parameters, and has good engineering applicability.

[0021] 5. Excellent durability and stable thermal conductivity in contact with cement: The spiral concave-convex structure forms a tight bond with the cement, effectively resisting the effects of thermal expansion and contraction during long-term use, preventing voids caused by separation between the underfloor heating pipes and the cement. Even after prolonged heat transfer, the bond remains stable, ensuring continuous and efficient heat conduction and significantly improving the durability and reliability of the underfloor heating system.

[0022] 6. Significant Energy-Saving Advantages in Construction: Traditional underfloor heating pipe installation typically requires a 15cm gap, while the spiral corrugated pipe of this application, due to its excellent thermal conductivity and structural design, allows for a gap of up to 18cm during installation. This improvement significantly reduces the length of pipes laid, reducing the amount of pipe used and lowering construction costs while maintaining the same heating effect. It also reduces energy consumption during material production and transportation, further achieving energy-saving goals. Attached Figure Description

[0023] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood in conjunction with the following description of the embodiments in conjunction with the accompanying drawings. It is obvious that the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. Wherein:

[0024] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0025] Figure 2 This is a schematic diagram of the cross-section of the present invention.

[0026] Explanation of reference numerals in the attached figures:

[0027] 1. Pipe body. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] like Figure 1-2 As shown in the figure, an embodiment of the present invention provides a graphene-based high thermal conductivity underfloor heating spiral pipe, comprising a pipe body 1. The outer wall of the pipe body 1 is provided with a plurality of protruding structures and groove structures, which are alternately arranged. Specifically, the protruding structures and groove structures can both be arranged around the axis of the pipe body 1. More specifically, the protruding structures and groove structures can be distributed in a spiral pattern on the outer wall of the pipe body 1. That is, the outer wall of the pipe body 1 is provided with a spiral-shaped concave-convex structure. The helix angle parameter of the spiral and the dimensions (such as depth, width, etc.) of the concave and convex structures can be selected according to actual conditions. As an example, the distance between two adjacent protruding structures (highest points) can be 3 mm.

[0030] By setting alternating raised and recessed portions on the outer wall of pipe body 1, a continuous spiral pattern is formed. After actual installation, when pipe body 1 bonds with cement, the raised portions embed themselves in the cement, while the recessed portions provide filling space for the cement. This interlocking mechanism greatly improves the density of the bond between the underfloor heating pipe and the cement. Compared to traditional underfloor heating pipes with smooth outer walls, the spiral concave-convex structure of this application increases the contact area between the underfloor heating pipe and the cement by more than 15%, significantly increasing the effective heat transfer area, thereby enabling heat to be transferred more efficiently from the underfloor heating pipe to the surrounding environment.

[0031] Please see Figure 1-2In one embodiment of the present invention, the interior of the pipe body 1 can be roughened, that is, a micro-roughened structure is provided on the inner wall of the pipe body 1. The micro-roughened structure can be a plurality of protrusions or a combination of protrusions and grooves. By providing a roughened structure on the inner wall of the pipe body 1, the turbulence of the hot water inside the pipe can be promoted, and the heat exchange efficiency between the hot water and the inner wall of the pipe can be enhanced. Combined with the spiral concave-convex structure of the outer wall, a highly efficient heat transfer channel is formed from the hot water inside the pipe to the external environment.

[0032] Please see Figure 1-2 In one embodiment of the present invention, the underfloor heating spiral pipe uses PERT material as the base pipe. During the raw material preparation process of the base pipe, graphene material is added in a specific proportion. Through an advanced mixing process, the graphene is uniformly dispersed in the PERT matrix to form a stable composite material system, giving the PERT base pipe excellent high thermal conductivity. Compared with traditional PERT material, its thermal conductivity is significantly improved. Specifically, the material of the pipe body 1 may include, by weight percentage:

[0033] PERT resin: 70%-85% (by weight), made from ethylene-octene copolymer, exhibiting good flexibility, low-temperature resistance, and processing properties. Its melt index is 0.5-3.0 g / 10 min (190℃, 2.16 kg), and its density is 0.920-0.940 g / cm³. 3 .

[0034] Graphene material: 10%-20% (by weight), using multilayer graphene microsheets with a layer thickness of 3-10nm, a sheet diameter of 5-20μm, a carbon content of ≥98%, and high specific surface area and excellent thermal conductivity.

[0035] Dispersant: 2%-5% (by weight), using maleic anhydride-grafted polyethylene (PE-g-MAH) or ethylene-vinyl acetate copolymer (EVA) with a grafting rate of 0.5%-2.0%, used to improve the dispersibility of graphene in the PERT matrix and reduce the melt viscosity of the composite material.

[0036] Antioxidant: 0.2%-1% (by weight), using a compound antioxidant system, such as hindered phenolic antioxidant 1010 and phosphite antioxidant 168 mixed in a 1:1 ratio, to effectively prevent oxidative degradation of materials during processing and use.

[0037] Light stabilizer: 0.1%-0.5% (by weight), using hindered amine light stabilizers (HALS), such as Chimassorb 944 or Tinuvin 770, to improve the aging resistance of the material and extend the service life of the underfloor heating pipes.

[0038] Lubricant: 0.3%-1% (by weight), preferably calcium stearate, PE wax or silicone powder, to improve the processing fluidity of the material and prevent the material from sticking to the mold during extrusion.

[0039] In one embodiment of the present invention, the material of the tube body 1 may further include 5%-10% by weight of nano-montmorillonite or nano-silica to enhance the mechanical properties and high-temperature resistance of the material. The interlayer spacing of the nano-montmorillonite is ≥3nm, and the particle size of the nano-silica is 20-50nm.

[0040] In one embodiment of the present invention, the tube body 1 is specifically processed by extrusion molding using a high-efficiency, high-shear single-screw extruder. The screw diameter is 65-90 mm, the length-to-diameter ratio (L / D) is 38-52:1, and the screw assembly design includes multiple mixing and shearing sections to ensure thorough mixing and dispersion of graphene and PERT resin. The main engine power can be 75-132 kW, and the extrusion rate is 200-500 kg / h.

[0041] Spiral Die: Utilizing a specially designed spiral die head, the die head features an internal spiral flow channel. The spiral angle of this channel matches the spiral angle of the concave-convex structure on the outer wall of the underfloor heating pipe, ensuring a uniform spiral distribution of the melt during extrusion. The die head is made of high-strength, corrosion-resistant H13 hot work die steel, with a nitrided surface achieving a hardness of HRC58-62.

[0042] Vacuum sizing sleeve: The inner wall of the sizing sleeve is designed with grooves that match the spiral concave-convex structure of the outer wall of the underfloor heating pipe. Through vacuum adsorption, the outer wall of the extruded pipe is formed into a precise spiral concave-convex shape. The length of the sizing sleeve is 800-1200mm, and the vacuum degree is controlled at 0.04-0.08MPa.

[0043] In one embodiment of the present invention, the molding process parameters are as follows:

[0044] Extrusion temperature: Zone 1: 180-200℃, Zone 2: 200-220℃, Zone 3: 220-230℃, Zone 4: 230-240℃, Die head: 220-235℃.

[0045] Screw speed: 20-40 rpm, adjusted according to pipe specifications and extrusion volume to ensure sufficient residence time of material in the barrel for good plasticization and dispersion.

[0046] Traction speed: 1-5m / min, matching the extrusion speed to ensure uniform wall thickness and dimensional stability of the pipe.

[0047] Cooling method: A multi-stage cooling water tank is used, with water temperatures of 60-70℃, 40-50℃, and 20-30℃ respectively. The total cooling length is 8-12m, ensuring that the pipe is fully cooled and shaped to avoid deformation.

[0048] In one embodiment of the present invention, the dispersion process of graphene in the material can be as follows:

[0049] An ultrasonic-assisted melt blending method is employed, in which an ultrasonic vibration device is installed in the feeding section of a single-screw extruder. The ultrasonic frequency is 20-40kHz, and the power is 500-1500W. During the material melting process, the cavitation effect of the ultrasound effectively breaks down graphene agglomerates, promoting its uniform dispersion in the PERT matrix. Alternatively, a masterbatch method can be used. Graphene and a portion of PERT resin are premixed in a high-speed mixer (1000-3000rpm, 5-10min), and then granulated using a twin-screw extruder to produce graphene masterbatch with a graphene content of 30%-50%. The masterbatch is then mixed with the remaining PERT resin and other additives according to the formulation ratio before pipe extrusion. This method improves the dispersion effect and production efficiency of graphene.

[0050] Working principle of the invention:

[0051] This underfloor heating spiral pipe uses PERT material as its base pipe, with graphene added in a specific ratio during the raw material preparation process. Through an advanced mixing process, graphene is uniformly dispersed within the PERT matrix, forming a stable composite material system. This endows the PERT base pipe with excellent high thermal conductivity, significantly improving its thermal conductivity compared to traditional PERT materials. During construction, the spiral pipe is laid according to the underfloor heating system design. Its concave-convex outer wall contacts the cement filling layer, utilizing the concave-convex structure to increase the adhesion and density between the pipe and the cement. During heating, hot water flows inside the pipe, and heat is efficiently transferred to the cement layer through the graphene-containing PE-RT pipe body 1 and the concave-convex outer wall, and then radiates heat into the room. Thanks to its large thermal conductivity area and high thermal conductivity, it rapidly raises the indoor temperature, achieving efficient heating.

[0052] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the scope of the claims.

[0053] In the description of this invention, it should be noted that the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0054] In the description of this invention, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0055] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

Claims

1. A graphene-based high thermal conductivity underfloor heating spiral pipe, characterized in that, The device includes a tube body, on the outer wall of which are provided several protruding structures and groove structures, with the protruding structures and groove structures arranged alternately.

2. The underfloor heating spiral pipe based on graphene with high thermal conductivity according to claim 1, characterized in that, The interior of the tube is roughened.

3. The underfloor heating spiral pipe based on graphene with high thermal conductivity according to claim 1, characterized in that, Both the protruding structure and the groove structure are arranged around the axis of the tube body.

4. The graphene-based high thermal conductivity underfloor heating spiral pipe according to claim 3, characterized in that, The protruding structures and the groove structures are distributed in a spiral pattern on the outer wall of the tube.

5. A graphene-based high thermal conductivity underfloor heating spiral pipe according to claim 4, characterized in that, The distance between two adjacent protrusions is 3mm.

6. The underfloor heating spiral pipe based on graphene with high thermal conductivity according to claim 1, characterized in that, The tube body is made of the following materials by weight percentage: 70%-85% PERT resin, 10%-20% graphene material, 2%-5% dispersant, 0.2%-1% antioxidant, 0.1%-0.5% light stabilizer and 0.3%-1% lubricant.

7. A graphene-based high thermal conductivity underfloor heating spiral pipe according to claim 6, characterized in that, The tube body is also made of 5%-10% by weight of nano-montmorillonite or nano-silica.

8. A graphene-based high thermal conductivity underfloor heating spiral pipe according to claim 1, characterized in that, The tube body is formed by extrusion using a single screw extruder with a length-to-diameter ratio of 38-52:1, a main power of 75-132kW, and an extrusion rate of 200-500kg / h.

9. A graphene-based high thermal conductivity underfloor heating spiral pipe according to claim 8, characterized in that, The extrusion temperatures of a single-screw extruder are as follows: Zone 1: 180-200℃, Zone 2: 200-220℃, Zone 3: 220-230℃, Zone 4: 230-240℃, and Die: 220-235℃.

10. A graphene-based high thermal conductivity underfloor heating spiral pipe according to claim 9, characterized in that, The screw speed of the single-screw extruder is 20-40 rpm, and the traction speed is 1-5 m / min.

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