In the fields of industrial heating, laboratory equipment, and even household appliances, the single head electric heating tube (Cartridge Heater) has become an indispensable key component for achieving local or point heating due to its compact structure, high thermal efficiency, easy installation, and precise temperature control. This article will delve into its working principle, core features, application scenarios, and key selection points.
1、 Definition and Structure: Compact Design Contains High Efficiency Energy
Single head electric heating tube, as the name suggests, is a tubular electric heating element with a single end lead wire. Its typical structure, from the inside out, includes:
1. Core heating element: High resistance alloy wire (such as nickel chromium alloy, iron chromium aluminum alloy) is usually used, tightly wound into a spiral shape, and is the core for converting electrical energy into thermal energy.
2. High thermal conductivity insulation filler: Modified magnesium oxide powder (MgO) with high purity and high thermal conductivity is uniformly filled between the resistance wire and the metal sheath under high voltage, serving the functions of insulation, thermal conductivity, and fixing the resistance wire. Its density and purity directly affect thermal conductivity efficiency and lifespan.
3. Metal sheath: Stainless steel (304, 316, 321, etc.), copper, titanium alloy and other materials are usually used to make the sealed tube shell. It protects the internal structure, withstands the working environment (high temperature, corrosion, pressure), and efficiently transfers heat to the heated object.
4. Lead terminal: It is led out from a single end and connected to the power supply, usually using high-temperature resistant wires (such as silicone wire, fiberglass braided wire) and insulated terminals (ceramic head, silicone sealing head, etc.) to ensure electrical safety.
5. Sealing material: The pipe mouth is sealed with special sealant (such as silicone, high-temperature epoxy resin) or mechanically pressed to isolate moisture and pollutants from entering, ensuring long-term stable internal insulation performance.
2、 Working principle: Electrothermal conversion, precise conduction
Single head electric heating tubes work according to the basic principle of Joule's law:
When current passes through the internal resistance alloy wire, electrical energy is converted into thermal energy.
2. The heat generated is rapidly and uniformly transferred to the entire surface of the metal sheath through highly conductive magnesium oxide powder.
3. The metal sheath efficiently transfers heat to tightly adhered heated objects (such as mold holes, metal blocks, liquids, etc.) through contact conduction, achieving heating of the target area.
3、 Core features and advantages
High power density, rapid heating: compact structure, high power can be arranged per unit volume/area, achieving rapid heating.
High thermal efficiency: The internal filling material has good thermal conductivity, and heat is mainly conducted through the contact surface, resulting in low losses.
Easy and flexible installation: Simply insert into the reserved hole or press into the heating hole, and use thermal paste for better results.
Accurate temperature control: In close contact with the heated object, combined with thermocouples and temperature controllers, high-precision temperature control (± 1 ° C to ± 5 ° C) can be achieved.
Good mechanical strength and long lifespan: The metal casing is sturdy and durable, with a lifespan of thousands or even tens of thousands of hours under reasonable use.
Strong adaptability: It can adapt to complex environments such as high temperature, corrosion, and pressure by selecting different sheath materials (stainless steel, copper, titanium, etc.), sealing forms, and lead lengths.
Good interchangeability: Standardized dimensions (diameter, length, power) are easy to replace and maintain.
4、 Key performance parameters
Rated voltage: Design working voltage (such as 12V, 24V, 110V, 220V, 380V).
Rated power: The electrical power (W) consumed under rated voltage and specified conditions.
Diameter (D) and length (L): Core dimensions determine its installation space and power density. Common diameters include Φ 3mm, Φ 4mm, Φ 6mm, Φ 8mm, Φ 10mm, Φ 12mm, Φ 16mm, Φ 20mm, etc.
Surface load: The power per unit heating surface area (W/cm ²) is a key indicator for design and selection! Excessive temperature can cause the sheath to overheat, accelerate oxidation, shorten its lifespan, or even burn out; If it is too low, the heating speed will be slow and the efficiency will be low. It needs to be determined comprehensively based on the material, temperature, and heat dissipation conditions of the heated object.
Maximum working temperature: the long-term safe working temperature allowed on the surface of the sheath.
Cold resistance: The resistance value (Ω) measured at room temperature, used to calculate power and check component status.