1. PTC thermistor is also called positive temperature coefficient thermistor, most of the current hot air curtain machines use this kind of heating element. After the current passes through the element, the temperature rises, that is, the temperature of the heating element rises. When the Curie point temperature (240 degrees) is exceeded, the resistance increases, thereby limiting the current increase, so the decrease of the current causes the temperature of the element to decrease, and the resistance value decreases. It also increases the circuit current and the temperature of the components, and it repeats itself, so it has the function of keeping the temperature in a specific range. The hot air curtain made of this component has the characteristics of fast heating, constant temperature and electricity saving, and it can also play a role in electrical appliances. Overheating protection. (PTC is mainly composed of barium titanate, supplemented by other polycrystalline ceramic materials.)
2. Some low-cost products add less barium titanate to PTC, which can't save electricity and have the effect of constant temperature.
3. In our daily use, we can check whether qualified PTC components are used by observing the current of the hot air curtain. After using the hot air curtain for 2 hours, the current should be in a downward trend, and the indicator should gradually fluctuate.
4. It should save energy about 50% when applied in the drying box, and about 30% when applied on the hot air curtain.
PTC heater manufacturers use the Joule effect of current to convert electrical energy into thermal energy to heat objects. Usually divided into direct resistance heating and indirect resistance heating. The power supply voltage of the former is directly applied to the object to be heated, and when current flows, the object to be heated will generate heat. The object that can be directly resistance heated must be a conductor, but it must have a higher resistivity. The high-temperature fan is internally heated because the heat is generated by the heated object itself, and the thermal efficiency is very high. Indirect resistance heating requires special alloy materials or non-metallic materials to make heating elements. The heating elements generate heat, which is transmitted to the object to be heated by means of radiation, convection and conduction.
1. Electric heating Since the heated object and the heating element are divided into two parts, the type of heated object is generally not limited, and the operation is simple. The resulting thermal effect causes the conductor itself to generate heat. According to the requirements of different heating processes, induction heating adopts AC power with power frequency (50-60 Hz), intermediate frequency (60-10000 Hz) and high-frequency (higher than 10000 Hz). The power frequency power supply is the AC power supply usually used in industry. The power frequency of most countries in the world is 50 Hz.
2. Electric heating The voltage of the industrial frequency power supply for induction heating applied to the induction device must be adjustable. According to the power of the heating equipment and the capacity of the power supply network, a high-voltage power supply (6-10 kV) can be used to supply power through a transformer; the heating equipment can also be directly connected to a 380-volt low-voltage power grid.