annelies rollez presentation

How the hair dryer works

For dummiesIonic 1800W BaByliss

Technological Design Engineering Annelies Rollez Academiejaar 2010-2011

1. History

1890: Alexandre F. Godefroy invented the hot air hairdyer

1925: - First hairdryer appaered on the market. -100 watts of heat the hair doesn’t dry quickly - The hairdryers were made of steel and zinc heavy

1925 -1945: - optimize the design - 300 watts of heat

1960: - Improvements in hairdryers’ technology: 500 watts of heat

1970: - Improving the safety of the hairdryers - the Consumer Products Safety Commission (CPSC) recommend guidelines that would create safer products.

1990: - Portable hairdryers: 1500 watts of heat - Plastic technology and insulating materials light weight

2000- ...: - can reach 2000 watts of heat


2. Disassembly

The housing

Air shaft

Heating-element with wrapped filaments

Fan and motor


Elements to have no filth into the fan

3. Working hair dryer

Hair dryer 2 superior parts : 1. Heating-element 2. Fan driven by a little motor

1. When you put the plug into the plug-socket the electric current flow through the hair dryer

2. Wrapped filaments of the heating element provided with that current warm up

3. Current also will also drive the motor, which will next drive the fan

4. The fan sucks air into the hair dryer air passes the filaments air takes up the warmth

5. Heated air leaves the hair dryer and dries the hair because it accelerate the evaporation of the water on the hair. Heat air raises the temperature of the air around the hair.


4. How each part works4.1. The motor

Electromagnetism and magnets important For the motors’ working process

The principle of the working of the motor:

- Contradictory poles attract each other- Identical poles reject each other

a rotating movement

4.1.1. Direct current motor



http://upload.wikimedia.org/wikipedia/commons/e/e6/Electric_motor_cycle_1.png

http://upload.wikimedia.org/wikipedia/commons/0/04/Electric_motor_cycle_2.png

http://upload.wikimedia.org/wikipedia/commons/5/59/Electric_motor_cycle_3.png


4.1.2. DC motor vs AC motor

•DC motors may be better for some very small applications costs less

• Smaller• Lighter

• AC motors are rugged and reliable• AC motors can operate at higher speeds• AC motors are available in larger power ratings• For larger applications

4.1.3. AC-DC converter

-By means of diodesA diode conducts the current just in one direction

-In this hair dryer: AC-DC converter = bridge rectifier

consist of 4 diodes


Current always flows in only one direction through the resistor.

Alternating current Direct current

4.2. The switches

To control the heat

To control the air speed


4.3. The heating element

Nichrome wire around isolating elements of mica

The air that goes through the fan and passes the elements of the heating Element much colder than the Temperature of the nichrome wires.Because of that, the air will absorb the warmth of the heating element.

the heat is dependent from the wattage of the hair dryer.Wattage electric current through the nichrome wire resistor Temperature


4.4. The fan

The air flow will be generated by the fan

The electric motor: electric energy

An air flow

Through the vent holes

Protected with an gauze, which protects the hair dryer against dust



4.5. Safety features

- When the fan is broken, the hair dryer can be overheated. To Protect the hair dryer against it, the hair dryer will be supplied with a safety sensor.So when the temperature gets to high, the hair dryer will stop working.When the hair dryer is totally cooling down, then they can use it again.

- When the vents become clogged with hair of dust, the hair dryer becomes earlier overheated and so will stop working.

4.5.1. Safety sensor


4.5.2. Safety cut off switch

Dryers contain a safety cut off switch that prevents the temperature of the drier from exceeding 60°C.

Switch is a bimetallic strip made of a sheet composed of 2 different metals. Both sheets expand when heated, but each at different rates

When the temperature inside the hair dryer the sheets heat up and bendsWhen it reaches a certain point, it trips a switch that cuts off power to the hair dryer

4.5.3. Thermal fuse


Thermal fuse included in the heating elementWhen the temperature or the current were excessively high thermal fuse will blow and break


4.5.4. Ground Fault Circuit interrupter (GFCI)

Is used to prevent accidental electrocution

by comparing the electrical going out through the black wire against that coming back through the white wire. If the difference is more than .005 amp, the system will be shut off.

4.5.5. Insulation


This is a sheet that’s around the heating element and that prevents the exterior of the hair dryer from getting hot.

5. Choice of materials5.1. The heating element

The heating element =

a tension spring of nichrome. It has a good development of heat because of two characteristics:

1. It doesn’t conduct very well

resistor is big enough to create warmth of the current

2. It doesn’t oxidize


5.2. The housing

-Polypropylene Advantages of this material:

1. Lightest2. Strong3. Equal to bacteria4. Eco Friendly

- All parts were made by ‘Injection Moulding’.

4 stages:

1. Melting2. Injecting3. Cooling4. Removing


6. The connections

the 2 parts of the housing 3 screws

The housing of the switches 3 screws


Click-connection


5. Calculations5.1. Motor

annelies rollez presentation

Documents