Four-layer sleeve type dry-burn-preventing vortex PTC heating pipe

Abstract

This invention discloses a four-layer sleeve-type anti-dry-burning eddy current PTC heating tube, aiming to provide a solution to the problems of traditional heating tubes such as easy damage from dry burning, low heating efficiency, high risk of leakage, and easy scaling. The key technical points are that the heating tube is coaxially nested from the inside out with a soft iron layer, a transverse rectangular corrugated channel layer, an insulation layer, and a coil winding layer. The soft iron layer is used to gather magnetic lines of force and improve the utilization rate of the magnetic field. The transverse rectangular corrugated channel layer serves as a fluid flow channel and is made of 316L-based alumina composite material. The insulation layer provides electrical isolation. The coil winding layer carries alternating current to generate an alternating magnetic field, which directly heats the fluid in the channel through the eddy current effect.

Description

Technical Field

[0001] This invention relates to the field of PTC heating equipment, specifically to a four-layer sleeve-type anti-dry-burning eddy current PTC heating tube. Background Technology

[0002] As the core component that converts electrical energy into heat energy, the performance of the heating element directly determines the efficiency, safety, and reliability of the thermal management system. Currently, the mainstream heating element technologies on the market mainly include two types: resistance heating elements and traditional ceramic PTC heating elements. However, both have significant shortcomings in practical applications: First, they pose certain prominent safety hazards: traditional resistance heating elements rely on grounding protection, and are prone to leakage accidents in environments without a ground wire or with an abnormal ground wire; under dry-burning conditions, the temperature of the resistance wire will rapidly rise to over 800℃, causing the insulation layer to break down, the heating element to burn out, and even causing a fire.

[0003] Meanwhile, the heating efficiency is low: resistance heating tubes transfer heat from the resistance wire to the tube wall and then to the fluid through thermal conduction. The energy transfer path is long, the heat loss is large, and the overall thermal efficiency is usually only 60%-70%. Although traditional ceramic PTC heating tubes have constant temperature characteristics, they have problems such as high thermal resistance and slow heating rate, making it difficult to meet the demand for rapid heating.

[0004] Currently, Chinese patent CN218648989U discloses a PTC heating tube structure and its water tank, which includes: an end cap, a connector, a PTC heating tube, and a heat dissipation tube; one end of the connector is connected to the end cap, and the end of the PTC heating tube is connected to the other end of the connector; the PTC heating tube is provided with at least one heat dissipation hole, and a heat dissipation cavity is also provided inside the PTC heating tube; the heat dissipation tube is disposed in the heat dissipation cavity, and the heat dissipation cavity communicates with the heat dissipation hole.

[0005] Although this PTC heating tube structure and its water tank enable the PTC heating tube to dissipate heat sufficiently when used for liquid heating, thus improving the liquid's heating efficiency, it still poses certain safety hazards. In addition, the heating tube is prone to creating flow dead zones, leading to localized overheating and scaling. Summary of the Invention

[0006] The purpose of this invention is to provide a four-layer sleeve-type anti-dry-burning eddy current PTC heating tube, which has the advantages of solving the core problems of traditional resistance heating tubes and existing PTC heating tubes, such as large leakage hazards, easy burnout due to dry burning, low heating efficiency, and easy generation of flow dead zones leading to local overheating and scaling.

[0007] The above-mentioned technical objective of the present invention is achieved through the following technical solution: A four-layer sleeve-type anti-dry-burning eddy current PTC heating tube includes, from the inside out, a soft iron layer, a transverse rectangular corrugated channel layer, an insulation layer, and a coil winding layer, which are coaxially nested and tightly fitted. The transverse rectangular corrugated channel layer serves as a flow channel for the fluid to be heated, and its inner wall is provided with a continuous transverse rectangular corrugated structure. When an alternating current of power frequency or medium frequency is applied to the coil winding layer, an alternating magnetic field is generated.

[0008] By adopting the above technical solution, the traditional resistance wire heat conduction heating method is abandoned. Instead, a non-contact eddy current heating principle is used, where heat is generated directly inside the fluid channel wall. This completely eliminates the multi-layer heat conduction loss from the resistance wire to the tube wall and then to the fluid in traditional heating tubes. The energy transfer path is minimized, and the overall thermal efficiency is improved, which can meet the application requirements of rapid heating. When an alternating current of power frequency or medium frequency is passed through the coil winding layer, an alternating magnetic field is generated. After the alternating magnetic field penetrates the insulation layer, eddy currents are induced in the transverse rectangular corrugated water channel layer. The Joule heating effect of the eddy currents is used to directly heat the fluid in the channel.

[0009] Further details: The transverse rectangular corrugated waterway layer is integrally molded using 316L-based alumina composite material.

[0010] By adopting the above technical solution, the conductivity of the composite material drops sharply by more than 90% when the temperature exceeds the critical value of 300℃, causing the eddy current heating effect to decay and eventually stop, thus achieving passive automatic anti-dry burning protection.

[0011] Further details: The soft iron layer is made of industrial pure soft iron material, and the surface is treated with rust prevention and passivation; the soft iron layer is used to gather the magnetic lines of force generated by the coil winding layer and serves as the internal support skeleton of the bushing structure.

[0012] By adopting the above technical solution, the soft iron layer, with its high magnetic permeability, can effectively concentrate the magnetic lines of force generated by the coil winding layer, reducing magnetic energy divergence loss and allowing more magnetic energy to be concentrated on the transverse rectangular corrugated channel layer, significantly enhancing the eddy current induction intensity and further improving heating efficiency and speed. Simultaneously, as the internal supporting framework of the overall sleeve structure, the soft iron layer can improve the mechanical strength and structural stability of the heating tube, ensuring that it does not deform under high-pressure conditions.

[0013] Further details: The insulating layer is made of alumina-boron nitride composite ceramic material, and the insulating layer completely isolates the coil winding layer from the transverse rectangular corrugated channel layer.

[0014] By adopting the above technical solution, the high-performance ceramic insulation layer can completely isolate the coil winding layer from the transverse rectangular corrugated channel layer, achieving reliable electrical isolation. Combined with the polyimide insulation layer outside the coil winding layer, it forms a double insulation protection system with excellent insulation performance at high temperatures. It can operate safely even in harsh electrical environments with no ground wire or abnormal ground wire, completely solving the problem of traditional heating tubes relying on grounding protection.

[0015] Further details: The coil winding layer is uniformly and densely wound with high-purity oxygen-free copper wire, and the coil winding layer is covered with a high-temperature resistant polyimide insulating layer.

[0016] By adopting the above technical solution, the high-purity oxygen-free copper wire has extremely low resistivity, which can effectively reduce the Joule heat loss of the coil itself and improve the efficiency of converting electrical energy into magnetic energy. The polyimide high-temperature resistant insulation layer covering the outside of the coil can not only withstand high-temperature environment, but also effectively shield electromagnetic interference, prevent the heating tube from affecting the surrounding electronic equipment, and reduce the heat loss of the coil, further improving the overall energy efficiency.

[0017] In summary, the present invention has the following beneficial effects: 1. Significantly improved safety and reliability Passive automatic anti-dry-burn protection: Utilizing the thermal sensitivity of 316L-based alumina composite material, it achieves anti-dry-burn protection with high reliability, fundamentally eliminating the risk of heating element burnout, insulation breakdown, and fire caused by dry burning; Double insulation protection: The alumina-boron nitride composite ceramic insulation layer and the outer polyimide insulation layer of the coil form a double insulation system, which can operate safely even in environments without a ground wire or with an abnormal ground wire; No exposed live parts: All live parts of the heating element are completely wrapped by the insulation layer, avoiding the risk of direct contact between fluid and live parts.

[0018] 2. Heating efficiency is significantly improved. Eddy current direct heating: Heat is generated directly inside the fluid channel wall, avoiding the multi-layer heat conduction loss of traditional heating tubes from the resistance wire to the tube wall and then to the fluid. The energy transfer path is short and the heat loss is minimal. Magnetic strengthening design: The soft iron layer concentrates and guides the magnetic lines of force to the water channel layer, improving the utilization rate of magnetic energy and significantly enhancing the eddy current induction intensity. Turbulent heat transfer enhancement: The transverse rectangular corrugated structure promotes the formation of turbulence in the fluid, improving the convective heat transfer coefficient.

[0019] 3. Excellent heat exchange uniformity and long service life No dead zones: The transverse rectangular corrugated water channel completely eliminates the dead zones of traditional circular water channels, ensuring uniform fluid temperature and avoiding local overheating and scaling; 316L-based alumina composite material combines the corrosion resistance of 316L stainless steel with the high-temperature resistance of alumina; No vulnerable parts: Adopting a non-contact heating principle, there are no easily aging resistance wires and electrodes, which is several times better than traditional heating tubes.

[0020] Compact structure, easy to install and maintain The four-layer coaxial integrated design is compact and small in size, making it easy to install in various equipment; the modular design is based on the fact that each heating tube is an independent functional unit, and multiple tubes can be connected in series through standard connectors, which provides convenience for subsequent power expansion. Attached Figure Description

[0021] The invention will be further described below with reference to the accompanying drawings.

[0022] Figure 1 This is a schematic diagram of the overall structure of a four-layer sleeve-type anti-dry-burning eddy current PTC heating tube.

[0023] In the diagram, 1 is the soft iron layer; 2 is the transverse rectangular corrugated channel layer; 3 is the insulation layer; 4 is the coil winding layer; 5 is the flow channel; and 6 is the transverse rectangular corrugated structure. Detailed Implementation

[0024] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0025] The technical solution adopted in this invention is: A four-layer sleeve-type anti-dry-burning eddy current PTC heating tube is integrally tubular, such as... Figure 1 As shown, the four layers from the inside out are tightly coaxially nested: Soft iron layer 1: Made of industrial pure soft iron DT4 material, the surface is treated with phosphate anti-rust passivation, which can effectively gather the magnetic lines of force generated by the coil winding layer 4, reduce magnetic energy divergence loss, and provide a solid internal support for the entire heating tube, ensuring that the sleeve structure does not deform under high pressure conditions.

[0026] Horizontal rectangular corrugated water channel layer 2: It is integrally formed using 316L-based alumina composite material. The inner wall of the water channel is uniformly provided with continuous horizontal rectangular corrugations. When the temperature rises to 320℃, the electrical conductivity of the material will drop sharply, and the eddy current heating effect will basically stop.

[0027] Insulation layer 3: Made of alumina-boron nitride composite ceramic material, which is made by hot pressing sintering process. It has excellent electrical insulation performance, heat resistance and mechanical strength, and can completely isolate the outer coil and the inner water channel layer, eliminating the risk of leakage and short circuit.

[0028] Coil winding layer 4: High-purity oxygen-free copper wire is used for uniform and dense winding. The coil is covered with a high-temperature resistant polyimide insulation layer 3, which can effectively shield electromagnetic interference and reduce heat loss.

[0029] Its main working principle is as follows: The working principle of this invention is divided into normal heating mode and anti-dry burning protection mode: Normal heating mode: When a 220V alternating current is applied to the coil winding layer 4, an alternating magnetic field that changes periodically with time is generated around the coil according to the principle of electromagnetic induction. The soft iron layer 1 utilizes its high magnetic permeability to concentrate and guide the magnetic lines of force to the transverse rectangular corrugated channel layer 2. The changing magnetic field induces closed eddy currents in the conductive channel layer. When the eddy currents flow inside the channel layer material, Joule heating is generated due to the material's resistance effect, directly heating the fluid inside the channel. At the same time, the transverse rectangular corrugated structure 6 promotes turbulence in the fluid, disrupts the laminar boundary layer, significantly improves heat exchange efficiency, and enables the fluid to heat up quickly and uniformly.

[0030] Anti-dry-burning protection mode: When dry burning occurs due to lack of water in the heating element, the heat from the water channel layer cannot be carried away by the fluid in time, causing the temperature to rise rapidly. When the temperature exceeds the critical temperature of the 316L-based alumina composite material, the alumina phase inside the material undergoes a martensitic phase transformation, leading to a sharp decrease in carrier concentration and a sudden drop in conductivity. Since eddy current intensity is proportional to the material's conductivity, the decrease in conductivity significantly weakens the eddy current intensity, resulting in a sharp decrease in heating power, ultimately causing the heating element to stop generating heat and achieving automatic anti-dry-burning protection. When the dry-burning condition is resolved and the water channel layer temperature drops below the critical temperature, the material's conductivity returns to normal, and the heating element can resume normal operation.

[0031] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the scope of the invention.

Claims

1. A four-layer sleeve-type anti-dry-burning eddy current PTC heating tube, characterized in that: It includes a soft iron layer (1), a transverse rectangular corrugated channel layer (2), an insulating layer (3), and a coil winding layer (4) that are coaxially nested and tightly fitted from the inside out; the transverse rectangular corrugated channel layer (2) is a flow channel (5) for the fluid to be heated, and its inner wall is provided with a continuous transverse rectangular corrugated structure (6); the coil winding layer (4) generates an alternating magnetic field when an industrial frequency or medium frequency alternating current is introduced.

2. The four-layer sleeve-type anti-dry-burning eddy current PTC heating tube according to claim 1, characterized in that: The transverse rectangular corrugated waterway layer (2) is integrally formed using 316L-based alumina composite material.

3. A four-layer sleeve-type anti-dry-burning eddy current PTC heating tube according to claim 2, characterized in that: The soft iron layer (1) is made of industrial pure soft iron material and the surface is treated with anti-rust passivation. The soft iron layer (1) is used to gather the magnetic lines of force generated by the coil winding layer (4) and serves as the internal support skeleton of the bushing structure.

4. A four-layer sleeve-type anti-dry-burning eddy current PTC heating tube according to claim 3, characterized in that: The insulating layer (3) is made of alumina-boron nitride composite ceramic material, and the insulating layer (3) completely isolates the coil winding layer (4) from the transverse rectangular corrugated channel layer (2).

5. A four-layer sleeve-type anti-dry-burning eddy current PTC heating tube according to claim 4, characterized in that: The coil winding layer (4) is made of high-purity oxygen-free copper wire that is uniformly and tightly wound, and the coil winding layer (4) is covered with a polyimide high-temperature resistant insulating layer (3).

Images