Sheathed electric heater (also known as tubular electric heater, armored heater) is a widely used industrial electric heating element. Its core design concept is to completely seal the resistance heating element inside a metal sheath, which can both efficiently generate heat and withstand harsh external environments.
⚡ Core Structure and Working Principle
The structure of a sheathed electric heater is like a sturdy "electric heating sandwich", mainly composed of three parts:
Central heating source: Inside is a resistance heating wire made of nickel-chromium or iron-chromium-aluminum alloy.
Intermediate insulating and heat-conducting layer: In the gap between the resistance wire and the outer tube, crystalline magnesium oxide powder (MgO) is tightly filled. It can both insulate and quickly conduct heat outward.
Outer metal sheath: Usually made of metal tubes such as stainless steel, copper, titanium, or carbon steel, which protect internal components, resist corrosion, and transfer heat.
The working principle is based on the Joule heating effect: current passes through the internal resistance wire to generate heat, which is quickly transferred to the surface of the metal sheath through the insulating and heat-conducting layer, and then the sheath conducts or radiates heat to the surrounding air, liquid, or solid media.
