Carbon fiber reinforced resin heat exchange tube

Abstract

The present application relates to a carbon fiber reinforced resin heat exchange tube, which is made of carbon fiber and thermoplastic resin as the main raw materials, and various additives, and is compounded into a thin-walled heat exchange tube through molding machines such as injection, extrusion, pultrusion, and casting. The present application has long fibers in the axial direction and basically no long fibers in the radial direction, and electrodes can be connected at both ends to heat the tube itself. When a circular composite material tube is connected to a tube of another shape such as an elliptical, polygonal or rectangular shape, it can be deformed by heating so that the port shape is changed and then docked or socketed. The present application can replace traditional thick-walled brittle graphite tubes and save heat exchange costs; the cross-section of the tube can be changed, so that the heat exchange area remains unchanged, and the flow rate of the fluid flowing through the tube can be changed, thereby adjusting the heat exchange efficiency.

Description

Technical Field

[0001] The present application relates to a device for heat exchange between cold and hot media. Background Art

[0002] The heat exchange tube is one of the components of the heat exchanger. It is placed inside the cylinder and is used for heat exchange between two media. It has high thermal conductivity and good isothermal properties. It is a device that can quickly transfer heat energy from one point to another with almost no heat loss.

[0003] Common materials for heat exchange tubes include carbon steel, low alloy steel, stainless steel, copper alloy, aluminum alloy, titanium alloy, etc. In addition, there are some non-metallic materials, such as graphite, ceramics, polytetrafluoroethylene, etc. When designing, the appropriate material should be selected according to the working pressure, temperature and medium corrosiveness.

[0004] Application No.: 2011100818115 A method for preparing a silicone-modified thermoplastic phenolic resin comprises the following steps: firstly mixing phenol and formaldehyde in a molar ratio of 1:0.2-10, stirring for 0.5-5h, heating to 40-60°C, adding ethyl orthosilicate and acid, then heating to 80-100°C, keeping the temperature for 0.2-12h, adding alkali to adjust the pH value of the reactant to between 6 and 7.5, and obtaining a product; and vacuum drying the product at 100-260°C for 0.1-5h, and obtaining a finished product.

[0005] The invention of application number: 2019111999093 provides a silicone-modified thermoplastic polyurethane elastomer and a preparation method thereof, which comprises the following components in parts by weight: 20-30 parts by weight of polyether polyol; 20-30 parts by weight of terminal hydroxyl-terminated polymethylphenylsiloxane; 8-13 parts by weight of diisocyanate; 20-25 parts by weight of polycarbonate; 4-10 parts by weight of chain extender; and 1-2 parts by weight of catalyst.

[0006] The above two patented products have both thermoplastic and elastic deformation properties, which can provide useful inspiration for this application. Summary of the invention

[0007] Purpose of the invention:

[0008] The disadvantages of traditional metal heat exchange tubes, such as poor corrosion resistance, and graphite tubes, such as large thickness, large brittleness and high price, are overcome, and a carbon fiber reinforced resin heat exchange tube with thin wall, light weight, high specific strength and changeable end face shape is provided.

[0009] Technical solution:

[0010] The carbon fiber reinforced resin heat exchange tube of the present application is made of carbon fiber (low specific gravity, high strength, electrical conductivity, high temperature resistance), thermosetting or high temperature resistant thermoplastic resin (polymer material) as main raw materials, and various additives, through injection, extrusion, pultrusion, casting and other molding machines to form a composite material tube (thickness of 1-5mm, normally 1.5-2.5mm is sufficient).

[0011] The carbon fiber is a combination of carbon fiber filaments, staple fibers, or long and short fibers. As a reinforcing material, it is preferred that the carbon fiber filaments are more distributed in the axial direction and less in the radial direction, so that the shape of the pipe mouth is easily deformed and the axial length is not easy to change. It is further preferred that there are long fibers in the axial direction and no long fibers in the radial direction. When long fibers in the axial direction are selected, pultrusion or casting is used for compounding. The composite material pipe obtained in this way has a higher thermal conductivity in the axial direction, a lower resistivity (between a good conductor and a dielectric, and can conduct electricity in the axial direction. The formed composite material has mechanical properties, thermoplasticity, elasticity, heat resistance, corrosion resistance, thermal conductivity and electrical conductivity.

[0012] The thermoplastic resin is polypropylene, PA66, PET, PBT, linear phenolic resin (higher heat resistance), linear epoxy resin, etc., with a heat deformation temperature higher than 100°C. The thermoplastic resin matrix allows the composite pipe to produce plastic deformation when heated, especially there is basically no long fiber in the radial direction, and the end face shape is easily deformed, such as the end face changes from a circle to an ellipse or other shapes.

[0013] In this application, 3-6% of flexible graphite powder can be used as the main filler, which not only enhances the mechanical strength, but also increases flexibility and improves stress performance. Alternatively, when graphene powder is preferably used as the main filler, the thermal conductivity and heat transfer performance of the composite material pipe are further improved, which is more conducive to use as a heat exchange pipe.

[0014] When the circular composite material tube of the present application is butt-jointed with other elliptical, polygonal or square (with arc corners) tubes, the tube mouth (end face) can be changed to an elliptical or square shape by heating and deforming, so as to facilitate butt-jointing with the latter.

[0015] Alternatively, when the composite pipe is connected to other pipes (such as metal pipes) with different end face shapes or pipe diameters, the end of the composite pipe is locally heated and a certain pressure is applied to change its wall thickness and size so that it can be sleeved around the end of the other pipe; then, due to cooling and shrinkage, the composite pipe sleeves the other pipe and achieves self-sealing.

[0016] The heating deformation of the present application preferably uses the carbon fiber inside the tube itself as a conductor, connects two electrodes of a power source at the two end faces, and utilizes the conductivity and certain resistivity of the axial carbon fiber to generate resistance heat to heat the tube itself, so that the resin softens, and circumferentially deforms along the length direction of the tube according to the shape of the mold (such as the outer wall mold and the core mold used together) to obtain a composite tube with another cross-sectional shape. No external electric heating element is required, which reduces the investment in additional heating equipment and improves the efficiency of electric heating of the tube.

[0017] Beneficial effects:

[0018] The composite material structure of the present application has a greater specific strength and wall rigidity; and the wall thickness is thin, light weight and high strength, and can replace the traditional thick-walled graphite heat exchange tube, thereby saving a large amount of carbon material and saving costs.

[0019] Because the thickness of the present invention is thin, the heat transfer effect of the cold and hot media is better. Traditional graphite tubes for heat exchange require thicker walls (5-20mm thickness) to have greater mechanical strength and stress resistance due to the lack of carbon fiber reinforcement fibers; and the heat transfer effect and heat exchange speed of the two internal and external fluids (heat medium and cold medium) are far inferior to those of the present invention.

[0020] The present application is used as a heat exchange pipe, and can replace thick, heavy, and brittle graphite tubes in multiple places with higher requirements on space dimensions, thereby improving heat exchange efficiency and saving heat exchange costs.

[0021] In this application, carbon fiber is mainly arranged axially, and has high tensile strength in the axial direction. There are basically no long fibers in the radial or circumferential direction, which are easy to be thermoplastically deformed, so that the cross section of the heat exchange tube can be softened and plastically deformed after being heated; and this deformation is after preheating and softening, and it does not deform during normal heat exchange (such as heat exchange between hot medium and cold medium of 100℃ hot water).

[0022] Carbon fiber and graphite powder have good electrical conductivity and heat transfer properties, and the electrical conductivity and heat transfer properties of the tube in the axial direction are good.

[0023] The traditional graphite tube production process is relatively long, requiring the preparation of a variety of raw materials, kneading, pressing, sintering, graphitization, and machining. The sintering and graphitization temperatures are as high as 2000-3000°C, which is polluting and consumes a lot of energy. The molding process of the composite material in this application is relatively short, requiring only raw material preparation, injection or pultrusion molding, heating and curing or cooling and hardening, and removal of scraps. There is basically no pollution, the molding temperature is 100-300°C, and the energy consumption is low.

[0024] The cross-section of the tube changes from circular, elliptical or other shapes, so that the heat exchange area remains unchanged, but the flow rate of the fluid in the tube can be changed; thereby, the flow rate of the heat medium and / or the coolant in the heat exchange can be adjusted, and the efficiency of the heat exchange can be designed and controlled. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a three-dimensional structural schematic diagram of the present invention;

[0026] Figure 2 It is another three-dimensional structural schematic diagram of the present invention;

[0027] Figure 3 yes Figure 1 A schematic diagram of a pipe mouth deformation;

[0028] Figure 4 yes Figure 1 Schematic diagram of another nozzle deformation.

[0029] In the figure, 1-circular tube body (cross section); 2-circular tube mouth (end face); 3-elliptical tube body; 4-elliptical tube mouth (end face); 5-polygonal tube mouth (end face); 6-deformed line. DETAILED DESCRIPTION

[0030] Embodiment 1:

[0031] A carbon fiber reinforced resin heat exchange tube, which is made of carbon fiber filaments, thermoplastic PET resin as main raw materials, and various additives, and is formed into a composite tube with a thickness of 2mm by injection or extrusion molding machinery. The cross-sectional shape of the composite tube is circular (i.e., it has a circular tube body 1) (such as Figure 1 As shown) or oval tube 3 (as Figure 2 As shown in Figure 2, PA66 resin is able to undergo plastic deformation when heated.

[0032] Embodiment 2:

[0033] Another carbon fiber reinforced resin heat exchange tube is made of carbon fiber filaments and short filaments, linear phenolic resin with graphene as filler as main raw materials, and various other additives, through pultrusion or casting molding machinery to form a composite tube with a thickness of 1.8mm; the main direction of the carbon fiber filaments is distributed along the axial direction of the tube, and there are basically no long fibers in the radial direction. When this thickness of tube is used as a heat exchange pipeline, its heat transfer effect is significantly better than that of a conventional graphite tube with a thickness of 5-10mm.

[0034] When the filler is 3-6% graphite powder, the thermal conductivity of the carbon fiber reinforced linear phenolic resin and graphite powder as filler extruded tube is 20-30 (W / (m·K).

[0035] When the filler is 3-6% graphene powder, the thermal conductivity of the extruded tube with carbon fiber reinforced phenolic resin and graphene powder as filler can reach 30-40 (W / (m·K), and the heat exchange effect is better.

[0036] The cross-sectional shape of the composite pipe is circular (i.e., it has a circular pipe body 1). When heated, the end face of one end of the pipe can undergo plastic deformation, changing from a circular pipe mouth 2 to a Figure 4 The oval nozzle 4 shown, or as Figure 3 The polygonal (quadrilateral) pipe mouth 5 with arc corners shown has a gradual deformation line 6 at the deformation portion; the cross section of the other end and the middle part of the pipe maintains the original cylindrical round pipe body 1 shape unchanged.

Claims

1. A carbon fiber reinforced resin heat exchange tube, which is made of fiber and resin as main raw materials, together with fillers and other additives, through injection, extrusion, winding or casting molding machinery processing to form a composite tube, and the composite tube is used as a heat exchange tube for refrigerant and heat medium; it is characterized by: The fibers are carbon fiber filaments, the main direction of the carbon fiber filaments is distributed along the axial direction of the tube, and there are basically no long fibers in the circumferential direction; the resin is a thermoplastic linear phenolic resin or linear epoxy resin with a heat deformation temperature higher than 100°C, and the filler is an inorganic non-metallic flexible graphite powder or graphene powder with good thermal conductivity at a weight ratio of 3-6%; the cross-sectional shape of the composite tube is circular, elliptical or polygonal with arc corners, and the wall thickness is 1.0-3.0mm; When the end surface of one or both ends of the pipe is locally heated to a temperature slightly higher than the thermal deformation temperature of the resin and a certain pressure is applied, the resin can be plastically deformed, and the end surface of the composite pipe can also change shape accordingly, changing to a circular pipe mouth (2), an elliptical pipe mouth (4) or a polygonal pipe mouth (5) with a circular arc corner that is different from the original shape, so as to have the same shape as the end surface of another pipe, which is convenient for docking or connection with pipe fittings; the cross section of the middle part of the pipe or the other end remains unchanged in the original shape.

2. The carbon fiber reinforced resin heat exchange tube according to claim 1, characterized in that: The heating is to connect two electrodes of a power source to the two end surfaces of the composite pipe respectively, and use the resistance heat generated by the axial carbon fibers themselves to heat the pipe itself, so that the thermoplastic resin softens and deforms.

3. The carbon fiber reinforced resin heat exchange tube according to claim 1 or 2, characterized in that: The fibers contain short carbon fiber filaments.

4. The carbon fiber reinforced resin heat exchange tube according to claim 1 or 2, characterized in that: When the composite pipe is connected to other pipes with different end face shapes or diameters, the end of the composite pipe is locally heated and a certain pressure is applied to change its wall thickness and size so that it can be sleeved around the end of the other pipe; then due to cooling and shrinkage, the composite pipe sleeves the other pipe and achieves self-sealing.

Images