Specifications
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13.11 Working of Hair Dryer :
The working of Hair dryer is much simpler and most of its mechanisms revolve around its
fan. When the dryer is switched on, the electricity moves to the windings of the motor of the fan.
And here the electrical energy is transformed to kinetic energy as it provides momentum to the
fan. The motor and the attached fan both spin. The centrifugal movement of the fan blades
draws air in through the small round air inlets in the side casing of the hair dryer. These holes
are covered by a safety screen that prevents other objects (such as strands of your hair) from
being sucked in as well.
The airflow thus generated by the fan is forced through the heating element by the shape of
the hair dryer casing. These coils are designed to get heated quickly using its electrical resistance
and electric current. When the air initially enters the barrel, it is much cooler than the nichrome
wire, so heat flows from the wire to the air, which becomes very hot. As the air is pushed along
by the fan and convection, it is replaced by cooler air and the cycle is repeated.The hot air
streams out the end of the barrel. The hot air thus emitted from a hair dryer increases the
temperature of the air surrounding each strand of hair. Since warm air can contain more moisture
than air at room temperature, more water can move from your hair into the air.
13.12 Hair Dryer Safety:
The basic idea behind hair dryers is pretty simple, but producing one for mass consumption
requires some hard thinking about safety features. Here are some other safety features hair
dryers commonly have:
Safety cut-off switch - Your scalp can be burned by temperatures more than 140
degrees Fahrenheit (approximately 60 degrees Celsius) To ensure that the air coming
out of the barrel never nears this temperature, hair dryers have some type of heat
sensor that trips the circuit and shuts off the motor when the temperature rises too
much. This hair dryer and many others rely on a simple bimetallic strip as a cut off
switch.
Fig.13.11 - Electrical wiring diagram of Hair dryer