Electric heater is a very popular electric heating equipment, which can generate huge heat through electric heating elements to achieve the purpose of supplying people for use. It can be widely used in chemical and petroleum industry, military industry, home indoor heating and other fields. So what are the heating methods of electric heating?
Resistance heating
The Joule effect of electric current is used to convert electrical energy into heat to heat objects. It is usually divided into direct resistance heating and indirect resistance heating. The power supply voltage of the former is directly applied to the heated object, and when current flows, the heated object itself (such as an electrically heated iron) heats up. An object that can be heated directly resistively must be a conductor, but with high resistivity. Since the heat is generated from the heated object itself, it belongs to internal heating, and the thermal efficiency is high. Indirect resistance heating needs to be made of special alloy materials or non-metallic materials to make heating elements, which generate heat energy and transmit to the heated object through radiation, convection and conduction. Since the heated object and the heating element are divided into two parts, the type of heated object is generally not limited and easy to operate.
Induction heating
The thermal effect of the conductor itself is heated by the induced current (eddy current) generated by the conductor in an alternating electromagnetic field. According to different heating process requirements, the frequency of AC power supply used in induction heating is power frequency (50~60 kHz), medium frequency (60~10000 Hz) and high frequency (higher than 10000 Hz). Power frequency power supply is usually used in industry AC power supply, most countries in the world power frequency is 50 Hz. The voltage applied to the induction device by the power frequency power supply for induction heating must be adjustable. According to the power of the heating equipment and the capacity of the power supply network, the power supply (6~10 kV) can be used to supply power through the transformer; The heating device can also be connected directly to the 380 volt low-voltage grid.
Arc heating
Heating objects using the high temperatures generated by an electric arc. Arcing is a gas discharge between two electrodes. The voltage of the arc is not high but the current is large, and its strong current is maintained by a large number of ions evaporated on the electrode, so the arc is easily affected by the surrounding magnetic field. When an arc is formed between the electrodes, the temperature of the arc column can reach 3000~6000K, which is suitable for high-temperature melting of metals.
Electron beam heating
Electrons moving at high speed under the action of an electric field are used to bombard the surface of an object and heat it. The main component for electron beam heating is the electron beam generator, also known as the electron gun. The electron gun is mainly composed of cathode, beam polyelectrode, anode, electromagnetic lens and deflection coil. The anode is grounded, the cathode is connected to the negative high position, the focusing beam is usually the same potential as the cathode, and an accelerated electric field is formed between the cathode and the anode. The electrons emitted by the cathode are accelerated to a very high speed under the action of the accelerating electric field, focused by the electromagnetic lens, and then controlled by the deflection coil, so that the electron beam shoots towards the heated object in a certain direction.
Infrared heating
Using infrared radiation objects, the object absorbs infrared rays, converts the radiant energy into heat energy and heats it.
Media heating
High-frequency electric fields are used to heat insulating materials. The main heating object is the dielectric. When the dielectric is placed in an alternating electric field, it will be repeatedly polarized (the phenomenon that the dielectric has an equal amount of charge opposite polarity on its surface or inside under the action of the electric field), thereby converting the electrical energy in the electric field into heat energy.
