Duct heater
Electric heating coil
It uses the Joule effect of electric current to convert electrical energy into thermal energy to heat objects. It is generally divided into direct resistance heating and indirect resistance heating. In the former, the power supply voltage is directly applied to the object to be heated. When current flows, the object itself
generates heat. Objects that can be directly resistance heated must be conductors with high resistivity. Since heat is generated within the object itself, it is internal heating with high thermal efficiency. Indirect resistance heating requires heating elements made of special alloy materials or non-metallic materials. These heating elements generate thermal energy, which is transferred to the object to be heated through radiation, convection, and conduction. Since the object to be heated and the heating element are two separate parts, the type of object to be heated is generally unrestricted, and operation is simple.
The materials used for heating elements in indirect resistance heating generally require high resistivity, low temperature coefficient of resistance, and stability at high temperatures.
