How the Inside of a Blow Dryer Works
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Wire
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Almost every type of hair dryer works according to the same basic principle: heated air is blown onto wet hair in order to make it dry faster. The differences between hair dryers come primarily in the methods used to heat the air that they blow. By far the most common type of hair dryer uses electrified coils of wire as a heating element. A fan at the rear end of the dryer sucks in outside air and blows it past the wire coils. Most of these types of dryers use nichrome wire, which is composed of a nickel and chromium alloy. According to the General Atomic Sciences Education Foundation, this alloy is non-magnetic, resistant to oxidization, and has a very high melting point, which makes it desirable as a heating element. Nichrome wire is also a poor conductor, which makes it relatively safe for use in conjunction with the dryer's electrical components.
Ceramic
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Hair dryers using ceramic heating elements are also quite common and are becoming more so as the technology decreases in cost. The advantages of ceramic elements come from their quick heating and cooling. They also provide a more evenly spaced heat for the air to pass through. While many ceramics have what is known as a negative thermal coefficient of resistance (NTC), ceramics such as barium titanate and lead titanate used in hair dryers have a positive thermal coefficient (PTC). According to the Georgia Institute of Technology, PTC ceramics work in the opposite manner of NTC ceramics in that their thermal conductivity increases with an increase in temperature. It is this property which allows them to heat up and cool down very quickly. Ceramic heating elements in hair dryers are often arranged in a honeycomb pattern to make the most of their surface area.
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Ionic
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Ionic hair dryers are usually also ceramic hair dryers in that they most commonly use a ceramic heating element. Like other hair dryers, they also work on the basic principle of blowing heated air onto wet hair to speed up the drying process. However, ionic hair dryers also have an added electrical component that bombards the heated air with negative ions, giving it a negative charge. Water molecules have a positive charge. Since opposite charges attract, the theory is that the negative ions from the hair dryer will bond with the positive water molecules, breaking them up into smaller components and drying hair faster while using less heat and being gentler on the hair. It should be noted, however, that ionic hair dryers have not been scientifically proven to be more effective than traditional hair dryers according to studies conducted by the Japanese Journal of Life Information Science.
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