We are all very familiar with the daily routine; we wash our hair and then automatically pick up the hairdryer, flip the switch and there is the hot air to dry quickly and let us get on with the day. There are good reasons for people to dry their hair with a hairdryer, going out with wet hair especially in the winter can be bad for our health, and lead to catching colds and chills. Most people though will probably not have considered how a hairdryer works and how the design allows the user to blow out hot air without us burning our hair or head.
The fundamentals of a hairdryer are very simple, there are two main parts which are essential to the workings and these are heat and air. So how do hairdryers work, quite simply the two elements are pushed together and the hot air is pushed through the funnel and out in one direction from the device. The heat is generated from an element inside the hairdryer; this will heat up very quickly, but this is no use if all the hot air is contained within the unit, firstly it will get very hot too touch and secondly the hairdryer will not perform the task that it is supposed too. The second part is the fan to push the air out of the dryer; this is a very simple motor which rotates the fan to push out the air and then you can dry your hair. Most hairdryers will also allow you to turn off the heating element and blow out cold air should you so wish.
Many of the hairdryers today will allow the user to regulate the heat and control how hot the air is that comes out of the dryer. The hotter the heating element the hotter the air will be that is pushed through to dry the hair. The heat is regulated normally by a heating coil, when the dryer is connected to the mains the coiled wires will warm up and become hot. The coil (nichrome wire) is made up of a number of two different alloy metals these are, nickel and chromium, you can find these in any number of household items including toasters and kettles. These two elements make excellent heat conductors, and nichrome wire is a poor conductor of electricity and therefore the alloy is very heat resistant which allows it to get very hot.
Another important element is the nichrome wire does not rust or oxidize; this is critical and allows the hairdryer to function properly and for a longer time period. When the air is pushed through the main body of the hair dryer it is cold before it reaches the element, depending on how long the air takes to pass through the dryer will dictate how hot the air will be when it leaves the other end. The regulation switch for the temperature will speed up the fan or slow it down and this then allows the temperature to be set correctly.