Resistance heating The coke effect of current is converted to heat energy to heat the object. It is usually divided into direct resistance heating and indirect resistance heating. The former’s power supply voltage is directly added to the heated object, and when there is current flow, heated the object itself (such as electric heating iron) is heated. A direct resistance heated object must be a conductor, but there is a high resistivity. Since heat is generated from the heated object itself, it belongs to internal heating and high personal heater thermal efficiency. An indirect resistance heating is required to be a special alloy material or a non-metallic material to generate a heat generating element, generating thermal energy by a heat generating element, transmitted to the heated object by radiation, convection and conducting, and the like. Since the heated object and the heat generating element are divided into two parts, the type of heated object is generally not limited, and the operation is simple. Electric heater heat resistance is better, dry-resistant, technology is mature, and the cost is relatively low. Safer, more efficient, more durable, more stable, and better matching performance. Power attenuation is small, so it can output rated power for a long time, and maintain a good heat generation effect for a long time. The electric heater has high mechanical strength, good sealing, high material tensile strength, good toughness, no crisp defects.