TWI386363B - Linear heater - Google Patents

Description

Line heat source

The invention relates to a line heat source, in particular to a line heat source based on a carbon nanotube.

Heat plays an important role in people's production, life, and research. One of the commonly used heat sources for line heat sources is widely used in electric heaters, infrared therapeutic devices, and electric heaters.

Referring to FIG. 1 , the prior art provides a line heat source 10 including a hollow cylindrical bracket 102; a heating layer 104 is disposed on the surface of the bracket 102, and an insulating protective layer 106 is disposed on the surface of the heating layer 104; They are respectively disposed at two ends of the bracket 102 and electrically connected to the heating layer 104; the two clamping members 108 respectively fix the two electrodes 110 and the heating layer 104 to both ends of the bracket 102. Wherein, the heating layer 104 is usually formed by winding or wrapping a carbon fiber paper. When a voltage is applied to the line heat source 10 through the two electrodes 110, the heating layer 104 generates Joule heat and thermally radiates to the surroundings. The carbon fiber paper includes a paper substrate and pitch-based carbon fibers that are disorderly distributed in the paper substrate. The paper substrate comprises a mixture of cellulose fibers and a resin, and the pitch-based carbon fibers have a diameter of 3 to 6 mm and a length of 5 to 20 μm.

However, the use of carbon fiber paper as the heating layer has the following disadvantages: First, the thickness of the carbon fiber paper is large, generally several tens of micrometers, making the line heat source difficult to be made into a micro structure and cannot be applied to the heating of the micro device. Second, since the carbon fiber paper contains a paper substrate, the carbon fiber paper has a large density and a large weight, which makes the use of the line heat source using the carbon fiber paper inconvenient. First Third, since the pitch-based carbon fiber in the carbon fiber paper is disorderly distributed, the carbon fiber paper has low strength, poor flexibility, and is easily broken, thereby limiting its proper range. Fourth, the heat conversion efficiency of carbon fiber paper is low, which is not conducive to energy conservation and environmental protection.

In view of this, it is necessary to provide a line heat source that is small in weight, high in strength, suitable for heating of a micro device, and has low electrothermal conversion efficiency, and is advantageous for energy saving and environmental protection.

A line heat source includes a linear substrate; a heating layer is disposed on a surface of the linear substrate; and two electrodes are disposed on the surface of the heating layer, and are respectively electrically connected to the heating layer, wherein the heating layer comprises a The carbon nanotube layer, and the carbon nanotube layer comprises a plurality of carbon nanotubes intertwined and disorderly arranged.

Compared with the prior art, the line heat source has the following advantages: First, the carbon nanotube can be conveniently fabricated into a carbon nanotube layer of any size, which can be applied to both macroscopic and microscopic fields. Second, the carbon nanotubes have a smaller density than the carbon fibers. Therefore, the line heat source using the carbon nanotube layer has a lighter weight and is convenient to use. Third, the carbon nanotube layer has high electrothermal conversion efficiency and low thermal resistance. Therefore, the line heat source has the characteristics of rapid temperature rise, small thermal hysteresis, and fast heat exchange rate. Fourth, the carbon nanotubes in the carbon nanotube layer are disorderly arranged, have good toughness, can be bent and folded into any shape without breaking, and thus have a long service life.

The line heat source of the present technical solution will be described in detail below with reference to the accompanying drawings.

Referring to FIG. 2 to FIG. 4, the embodiment of the present invention provides a line heat source 20, which includes a linear substrate 202. A reflective layer 210 is disposed on the surface of the linear substrate 202. A heating layer 204 is disposed at the surface. The surface of the reflective layer 210 is disposed on the surface of the heating layer 204 and electrically connected to the heating layer 204; and an insulating protective layer 208 is disposed on the surface of the heating layer 204. The length of the line heat source 20 is not limited, and the diameter is from 0.1 micrometer to 1.5 centimeters. The diameter of the line heat source 20 of the present embodiment is preferably 1.1 mm to 1.1 cm.

The linear substrate 202 serves as a supporting material, and the material thereof may be a hard material such as ceramics, glass, resin, quartz, etc., and a flexible material such as plastic or flexible fiber may also be selected. When the linear substrate 202 is a flexible material, the linear heat source 20 can be bent into any shape as needed when used. The length, diameter and shape of the linear substrate 202 are not limited, and may be selected according to actual needs. The preferred linear substrate 202 of this embodiment is a ceramic rod having a diameter of from 1 mm to 1 cm.

The material of the reflective layer 210 is a white insulating material such as a metal oxide, a metal salt or a ceramic. In this embodiment, the material of the reflective layer 210 is preferably aluminum oxide, and the thickness thereof is 100 micrometers to 0.5 millimeters. The reflective layer 210 is deposited on the surface of the linear substrate 202 by sputtering. The reflective layer 210 is used to reflect the heat generated by the heating layer 204 to be effectively radiated to the external space. Therefore, the reflective layer 210 is an optional structure.

The heating layer 204 includes a carbon nanotube layer. The carbon nanotube layer may be wrapped or wound around the surface of the reflective layer 210. The carbon nanotube layer may be connected to the reflective layer 210 by its own viscosity, or may be further connected to the reflective layer 210 by a binder. The binder is silicone. Understand that when When the line heat source 20 does not include the reflective layer 210, the heating layer 204 may be directly wrapped or wound around the surface of the linear substrate 202.

The length, width and thickness of the carbon nanotube layer are not limited and can be selected according to actual needs. The carbon nanotube layer provided by the technical solution has a length of 1 to 10 cm, a width of 1 to 10 cm, and a thickness of 1 to 2 mm. It can be understood that the thermal response speed of the carbon nanotube layer is related to its thickness. In the case of the same area, the greater the thickness of the carbon nanotube layer, the slower the thermal response speed; conversely, the smaller the thickness of the carbon nanotube layer, the faster the thermal response speed.

The carbon nanotube layer comprises intertwined carbon nanotubes, see Figure 4. The carbon nanotubes are attracted and entangled by van der Waals force to form a network structure. In the carbon nanotube layer, the carbon nanotubes are uniformly distributed and randomly arranged, so that the carbon nanotube layer is isotropic; the carbon nanotubes are intertwined, so the carbon nanotube layer has a good The flexibility is bendable into any shape without breaking, see Figure 5. The carbon nanotubes in the carbon nanotube layer include one or more of a single-walled carbon nanotube, a double-walled carbon nanotube, and a multi-walled carbon nanotube. The single-walled carbon nanotube has a diameter of 0.5 nm to 10 nm, the double-walled carbon nanotube has a diameter of 1.0 nm to 15 nm, and the multi-walled carbon nanotube has a diameter of 1.5 nm to 50 nm. Nano. The length of the carbon nanotubes is greater than 50 microns. In this embodiment, the length of the carbon nanotubes is preferably 200 to 900 μm.

In this embodiment, the heating layer 204 is a carbon nanotube layer having a thickness of 100 μm. The carbon nanotube layer has a length of 5 cm and the carbon nanotube film has a width of 3 cm. The carbon nanotube layer is wrapped around the surface of the reflective layer 210 by the viscosity of the carbon nanotube layer itself.

The electrodes 206 may be disposed on the same surface of the heating layer 204 or on different surfaces of the heating layer 204. The electrode 206 may be disposed on the surface of the heating layer 204 through a viscous or conductive adhesive (not shown) of the carbon nanotube layer. The conductive adhesive allows the electrode 206 to be in electrical contact with the carbon nanotube layer while also better securing the electrode 206 to the surface of the carbon nanotube layer. A voltage can be applied to the heating layer 204 through the two electrodes 206. Wherein, the two electrodes 206 are spaced apart from each other so as to connect a certain resistance value when the heating layer 204 using the carbon nanotube layer is energized to avoid short circuit. Preferably, since the linear substrate 202 has a small diameter, the two electrodes 206 are spaced apart from both ends of the linear substrate 202 and surround the surface of the heating layer 204.

The electrode 206 is a conductive film, a metal sheet or a metal lead. The material of the conductive film may be metal, alloy, indium tin oxide (ITO), antimony tin oxide (ATO), conductive silver paste, conductive polymer, or the like. The conductive film may be formed on the surface of the heating layer 204 by physical vapor deposition, chemical vapor deposition, or the like. The material of the metal piece or the metal lead may be a copper piece or an aluminum piece or the like. The metal sheet may be fixed to the surface of the heating layer 204 by a conductive adhesive.

The electrode 206 can also be a carbon nanotube structure. The carbon nanotube structure is wrapped or wound around the surface of the reflective layer 210. The carbon nanotube structure can be fixed to the surface of the reflective layer 210 by its own viscous or conductive adhesive. The carbon nanotube structure includes aligned and uniformly distributed metallic carbon nanotubes. Specifically, the carbon nanotube structure comprises at least one ordered carbon nanotube film or at least one nano carbon tube long line.

In this embodiment, preferably, two ordered carbon nanotube films are separately provided. Both ends along the longitudinal direction of the linear substrate 202 are placed as the electrodes 206. The two ordered carbon nanotube films surround the inner surface of the heating layer 204 and form electrical contact with the heating layer 204 by a conductive bonding agent. The conductive adhesive is preferably a silver paste. Since the heating layer 204 in this embodiment also uses a carbon nanotube layer, the electrode 206 and the heating layer 204 have a small ohmic contact resistance, which can improve the utilization of the electric energy by the line heat source 20.

The material of the insulating protective layer 208 is an insulating material such as rubber, resin or the like. The thickness of the insulating protection layer 208 is not limited and may be selected according to actual conditions. In this embodiment, the insulating protective layer 208 is made of rubber and has a thickness of 0.5 to 2 mm. The insulating protective layer 208 may be formed on the surface of the heating layer 204 by a coating or wrapping method. The insulating protective layer 208 is used to prevent the line heat source 20 from making electrical contact with the outside when in use, and also prevents the carbon nanotube layer in the heating layer 204 from adsorbing external impurities. The insulating protective layer 208 is an optional structure.

In this embodiment, the thermoelectric properties of the carbon nanotube layer having a thickness of 100 μm were measured. The carbon nanotube layer is 5 cm long and 3 cm wide. The carbon nanotube layer was wrapped on a linear substrate 202 having a diameter of 1 cm, and its length between the two electrodes 206 was 3 cm. Current flows in the length direction of the linear substrate 202. The measuring instrument is an infrared thermometer AZ-8859. When the applied voltage is between 1 volt and 20 volts and the heating power is 1 watt to 40 watts, the surface temperature of the carbon nanotube layer is 50 ° C to 500 ° C. It can be seen that the carbon nanotube layer has a high electrothermal conversion efficiency. For an object with a black body structure, the corresponding temperature of 200 ° C ~ 450 ° C can emit heat radiation (infrared) that is invisible to the human eye. At this time, the heat radiation is the most stable and efficient, and the heat radiation is generated. The largest amount.

When the line heat source 20 is used, it can be placed on the surface of the object to be heated or placed at an interval from the object to be heated, and can be heated by the heat radiation. Alternatively, a plurality of the line heat sources 20 may be arranged for use in various predetermined patterns. The line heat source 20 can be widely used in the fields of electric heaters, infrared therapeutic devices, electric heaters and the like.

In the present embodiment, since the carbon nanotubes have a diameter of a nanometer order, the prepared carbon nanotube structure can have a small thickness, and therefore, a microwire heat source can be prepared by using a small-diameter linear substrate. The carbon nanotubes have strong corrosion resistance, making them work in an acidic environment. Moreover, the carbon nanotubes have extremely high stability, and do not decompose even when working in a vacuum environment at a high temperature of 3000 ° C or higher, so that the line heat source 20 is suitable for operation under vacuum high temperature. In addition, the carbon nanotubes are 100 times stronger than the same volume of steel, and the weight is only 1/6. Therefore, the line heat source 20 using the carbon nanotubes has higher strength and lighter weight.

In summary, the present invention has indeed met the requirements of the invention patent, and has filed a patent application according to law. However, the above description is only a preferred embodiment of the present invention, and it is not possible to limit the scope of the patent application of the present invention. Equivalent modifications or variations made by persons skilled in the art in light of the spirit of the invention are intended to be included within the scope of the following claims.

10,20‧‧‧Wire heat source

102‧‧‧ bracket

104,204‧‧‧heating layer

106‧‧‧Protective layer

108‧‧‧Clamping parts

110,206‧‧‧ electrodes

202‧‧‧Linear substrate

208‧‧‧Insulating protective layer

210‧‧‧reflective layer

1 is a schematic structural view of a prior art line heat source.

2 is a schematic structural diagram of a line heat source according to an embodiment of the present technical solution

3 is a schematic cross-sectional view of the line heat source of FIG. 2 taken along line III-III.

4 is a cross-sectional view of the line heat source of FIG. 3 taken along line IV-IV.

FIG. 5 is a scanning electron micrograph of a carbon nanotube layer according to an embodiment of the present technical solution.

Figure 6 is a photograph of a carbon nanotube layer of an embodiment of the present technical solution.

20‧‧‧Wire heat source

202‧‧‧Linear substrate

204‧‧‧heating layer

206‧‧‧ electrodes

208‧‧‧Insulating protective layer

210‧‧‧reflective layer

Claims (17)

A line heat source comprising: a linear substrate; a heating layer disposed on a surface of the linear substrate; and two electrodes spaced apart and electrically connected to the heating layer, respectively, wherein the heating layer comprises a The carbon nanotube layer, the carbon nanotube layer comprises a plurality of carbon nanotubes intertwined, disorderly arranged, and the two electrodes are electrically connected through the carbon nanotube layer. The line heat source according to claim 1, wherein the carbon nanotubes in the carbon nanotube layer are attracted to each other by a van der Waals force to form a network structure. The line heat source according to claim 1, wherein the carbon nanotubes are evenly distributed and randomly arranged, and the carbon nanotube layer is isotropic. The line heat source of claim 1, wherein the carbon nanotube layer has a thickness of from 1 micrometer to 2 millimeters. The line heat source of claim 1, wherein the carbon nanotubes have a length greater than 50 microns and a diameter less than 50 nanometers. The line heat source of claim 1, wherein the carbon nanotube layer is wound or wrapped on a surface of the linear substrate. The line heat source according to claim 1, wherein the carbon nanotube layer is fixed to the surface of the linear substrate by a bonding agent or a self-adhesive property. The line heat source of claim 1, wherein the two electrodes are disposed on a surface of the heating layer. The line heat source according to claim 1, wherein the electrode is a conductive film, a metal piece, a metal lead or a carbon nanotube structure. The line heat source of claim 9, wherein the carbon nanotube structure comprises aligned and uniformly distributed metallic carbon nanotubes. The line heat source of claim 9, wherein the carbon nanotube structure comprises at least one ordered carbon nanotube film or at least one carbon nanotube long line. The line heat source of claim 9, wherein the carbon nanotube structure is wrapped or wound around a surface of the heating layer. The line heat source of claim 9, wherein the carbon nanotube structure is fixed to the surface of the heating layer by its own viscous or conductive adhesive. The linear heat source according to claim 1, wherein the material of the linear substrate is a flexible material or a hard material, and the flexible material is plastic or flexible fiber, and the hard material is ceramic, glass, resin. ,quartz. The line heat source according to claim 1, wherein the line heat source further comprises a reflective layer disposed between the heating layer and the linear substrate, and the material of the reflective layer is a metal oxide, a metal salt or a ceramic. The thickness is from 100 micrometers to 0.5 millimeters. The line heat source of claim 1, wherein the line heat source further comprises an insulating protective layer disposed on an outer surface of the heating layer. The line heat source according to claim 1, wherein the line heat source has a diameter of 0.1 μm to 1.5 cm.