Tubular heater
Tubular heating elements are used for electrical heating of gaseous or liquid media. The simplest version is the immersion heater , which in principle only consists of a tubular heating element with a heat-insulating handle.
construction
Tubular heating elements consist of an aluminum, copper, manganese or stainless steel tube with a diameter of approx. 3–16 mm into which a corrugated or coiled heating resistor - i.e. an electrically heated wire - is inserted, which is connected via ceramic spacers (e.g. from Magnesium oxide) is kept away from the inner wall of the enclosing pipe. At the ends of the pipe, the heating wire is usually welded to highly conductive connection electrodes, which lead to the outside through the seal at the ends of the pipe. The ends of the tubular heating elements are therefore not heated and are usually attached to the surrounding device there. In addition to being fastened to the pipe ends, it is also common for longer lengths to support the tubular heating element at other points against a surrounding device. The electrical connection is made e.g. B. via plug connections, mostly directly to the mains voltage. In special forms, flattened pipes are used or both connections of the heating element are brought out at one end.
Areas of application
liquids
Tubular heating elements can be found in many household appliances that electrically heat water or fat:
- Deep fryers
- Washing machines
- Coffee machines
- Dishwasher (previously arranged directly in the washroom, now mostly integrated in the form of a flow heater in the inaccessible part of the machine).
air
In rare cases, tubular heating elements are also used to heat the air: Compared to PTC elements , however, tubular heating elements have a smaller surface - in order to achieve the same level of air heating, the tube surface has to be heated more, which can lead to carbonization of dust particles. The advantage of tubular heating elements over PTC elements is their lower flow resistance.
Advantages and differentiation
Tubular heaters always have an advantage over bare wire heating when the heating source has to be protected mechanically - e.g. B. in the deep fryer in front of the hanging basket, in the dishwasher and washing machine from dirt.