Heating elements usually consist of a coil, ribbon, and a wire that gives off heat. When a voltage flows through it, it will glow bright hot red and convert the electrical energy into heat energy which will radiate out in all directions.
Heating elements are usually made of nickel or iron. The ones made of nickel are usually nichrome which consists of almost 80% nickel and 20% chromium. There are so many reasons why nichrome is the most famous heating element material. Nichrome has a very high melting point – 1400°C. It doesn’t oxidize at high temperatures and only expands very little when it heats up. Nichrome also has a very reasonable resistance.
Types of Heating Elements
There are various kinds of heating elements. Sometimes the nichrome used is bare, other times it is embedded in a ceramic material to make it more durable. Ceramics are very good at coping with very high temperature and can withstand a lot of continuous heating and cooling. The dimensions of the heating appliance largely governs the size and shape of a heating element as it has to fit properly inside and the area over which it requires to produce heat. Hair curling tongs have coiled shorter elements because they need to produce heat over a thin tube in which hair will be wrapped around. Electric radiators on the other hand, have long bar elements because they need to throw heat out across the room’s wide area. Electric stoves have coiled heated elements just the suitable size to heat cooking pans. Usually electric stoves will be made of ceramics, glass or metal so that they are easier to clean afterwards.
The heating elements are very visible in a lot of appliances these days. For instance in an electric toaster, it is very easy to spot the nichrome ribbons built into the toaster because it glows bright hot red once switched on. Electrical radiators, make heat with glowing red coiled bars while electrical converter heaters have circular and concentric heating elements position right in front of electrical fans which enables them to transport heat faster by convection. There are appliances which has visible elements that work at much lower temperature and do not glow such as electric kettles which only operate at the boiling point of water. For safety reasons too, many appliances have their heating elements completely concealed like electrical showers and hair straighteners or flat irons so that the risk of electrocution can be successfully lowered.
Heating elements may sound very simple and straightforward, but there are many different factors that electrical and electronic engineers have to consider when they design them. Did you know that there are estimated 20 to 30 different factors that can affect the performance of a heating element? This includes things like the voltage and current, the resistance (the diameter of the element and type of material will affect this) and of course, the operating temperature. There are also specific factors you need to consider for each different type of element. For example, with round wire made into a coiled element, the diameters of the wire and the pitch as well as stretch of the coil are among the things that critically affect the performance. However, with a ribbon element, the thickness, width and surface area of the ribbon will all be factored in.