Manufacturers of cartridge heaters develop a wide variety of heating devices based on the principle of electric heat and supply the market with them. Important and frequently used electric heaters are
tubular heating elements
Screw-in heating elements
High-performance heating cartridges
Tubular heating elements
A metal pipe made of aluminium, copper, manganese or stainless steel with an internal diameter of approx. 3 - 16 mm contains a corrugated or coiled heating resistor inside, which is heated with electric current. For safety reasons, the heating resistor must not come into contact with the pipe wall, so it is kept away from the metal pipe by ceramic intermediate elements.
Since the ends of the tubular heating elements are often connected to a device, for example a washing machine, via sealing elements, these ends must not be heated either. Therefore, the heating wire is led outwards a little from the end of the tubular heater and welded to a connecting electrode. Tubular heating elements heat gaseous and liquid substances.
Screw-in heating elements
With this type of heating element, several heating loops are arranged in parallel with a certain distance between them. The individual heating loops are always kept at the same distance with spacers. This minimizes flow losses caused by flowing media that pass through the heating loops. Such a screw-in heating element is attached to the device, for example a car wash, by means of a standardized screw-in thread (1", 11/4", 11/2", 2", 21/2").
Thermocouples are used in the field of temperature measurement technology. They consist of two different metals, which are connected to each other at a certain distance by soldering joints. One connection point serves as measuring point, the other as reference point. At different temperatures, the Seebeck effect causes a thermoelectric voltage at the two connection points, which causes a small current in the thermocouple.
Temperatures of machines and plants, but also temperatures during processing operations, for example in the food industry, often have to be constantly monitored. Temperature sensors on an electronic basis record the exact ambient temperatures and are thus important control and regulation elements with which manufacturing processes can be controlled in a targeted manner.
In injection moulding technology, heatable tools are often used. These mould heatings require the use of heating cartridges with high specific heat outputs per unit area on the cartridge surfaces. High-performance heating cartridges have the following properties:
High specific surface heating power up to 50 W/cm2 at the shell surface
Working temperatures of max. 750 °C at the jacket surface
Mechanically highly resilient
Electric heating elements are suitable in heating systems both as emergency heating and as additional heating. They are therefore often used to heat water in heating systems. However, the range of application can be extended considerably, as they can also be used to heat other liquid media.
Heating elements can provide beneficial services to improve hygiene. From time to time, they can easily be used to heat tap water to a temperature of 70 to 75 °C. In this way the formation of legionella can be effectively prevented.
Common applications of heating elements are hot water boilers, washing machines and dishwashers. Models with thermostats, on which the desired temperatures can be set, are particularly suitable for operation in hot water boilers.
Generating heat with electric current
If there is a potential difference in a closed circuit, a current flows through the conductor. The electric current is caused by charge separation, by the movement of free valence electrons of the atoms or molecules of the conductor. The atoms or molecules of matter carry out uncontrolled oscillating movements in space already at room temperature due to Brown's molecular movement. These small oscillatory movements are now additionally disturbed and intensified by the movement of the free valence electrons. The inevitably arising friction causes heat, the conductor heats up.
Conclusion heating cartridges
Heating cartridges can be used for numerous applications in which water or other liquid media must be heated. Due to the numerous design variants of cartridge heaters, almost all applications can be covered economically. On the one hand a good efficiency is achieved and on the other hand the health aspect is also taken into account.