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How does a hairdryer work?


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October 18, 2011 10:20PM

I was just wondering about this myself the other day, provides many useful explanations of how commonplace items and many other things work. See the link at the left.

the hair dryer dries your hair by speeding up the evaporation of water from the hair's surface. the hot air 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. the incease in temperature also makes it easier for the individual molecules in a water droplet to overcome their attraction to one another and move from a liquid to a gas state.
There are two basic things to a hairdryer. They are heat and air. How the hairdryer works is the two things, heat and air are pushed together and the hot air is pushed through the funnel and out in one direction. The heat is made from something inside the hairdryer that heats up very quickly. First the hairdryer will get too hot to touch. The second part is when the fan pushes the air out of the hairdryer by a very simple motor that rotates the fan to push out the air and then you can dry your hair. Most hairdryers also allow you to turn off the heat and turn on cold air if you want. A lot of the hairdryers today will allow you to change the heat and how fast the air comes out. The hotter the hairdryer gets the hotter the air will be. A heating coil makes the heat. When the dryer is connected to the mains the coiled wires will warm up. The coil is made up of a number of two different metals these are, nickel and chromium like on toaster oven. Nichrome wire is a poor maker of electricity and so it is very heat resistant so that is why the hairdryer allows it to get very hot. The nichrome wire does not rust, which allows the hairdryer to function right and for a longer time. Nichrome wire is just a coiled wire that's wrapped around insulating mica boards. When the air is pushed through the main body of the hairdryer. It is cold before it reaches the element, depending on how long the air takes to pass through the dryer. This will choose how hot the air will be when it leaves through the other end. The switch for the temperature will speed up the fan or slow it down which allows the temperature to be set correctly. The hairdryer dries your hair by speeding up the evaporation of water, and increases the temperature of the air. When you plug in the hairdryer and turn it on currents go through the hairdryer. The circuit first supplies power to the heating element, like tourmaline-infused ceramic coating. The current that went through the hairdryer when you turn it on is what makes the little fan inside turn. The air made by the fan is blown down the barrel of the hairdryer. As the air goes through the coiled wire or the tourmaline-infused ceramic coating, the heat warms the air by forced convection. Then the hot air steams out of the end of the funnel. The fan in the hairdryer looks like a hydraulic turbine aka a water wheel. It isn't like a water wheel though because water wheels make the potential energy of flowing water to generate power. The fan in a hairdryer uses electrical energy to generate power. The small motor actually sits inside the fan, which is firmly attached to the top of the motor. When you turn the hairdryer on it gives power to the motor so the motor and the fan that's attached both spin. The movement of the fan blades takes air in through the small round air inlets on the side of the hair dryer. These holes are covered by a safety screen. The safety screen prevents other objects from being sucked in as well. When you want to change the speed of the airflow it involves changing the speed at which the motor is turning. This is done very easily by changing the current going through the part of the circuit giving the motor power. When the power is low, the motor and the fan spin slowly. Less air is pushed through the hair dryer. When there's more power, the motor speeds up. The fan rotates very fast, taking in more air and making the airflow bigger. There is a heat shield on the barrel of the hairdryer that keeps the barrel safe from getting too hot. To make sure that the air coming out of the barrel never gets near 140 degrees, hair dryers have some type of heat sensor that trips the circuit and shuts off the motor when the temperature gets too high. The switch is a simple bimetallic strip.

The bimetallic strip is made out of sheets of two metals, both expand when heated but at different rates. When the temperature rises inside the hairdryer, the strip heats up and bends because one metal sheet has grown larger than the other. When it reaches a certain point, it trips a switch that cuts off power to the hairdryer. For more protections for overheating and catching fire, there is often a thermal fuse included in the heating element circuit. This fuse will blow and break the circuit if the temperature and current are excessively high. Without the proper insulation, the outside of the hairdryer would become extremely hot to the touch. If you grabbed it by the barrel after using it, it might seriously burn your hand. To prevent this, hairdryers have a heat shield of insulation material that lines the plastic barrel. When air is drawn into the hairdryer as the fan blades turn, other things outside the hairdryer are also pulled toward the air intake. This is why you will find a wire screen covering the air holes on either side of the dryer. After you have used a hairdryer for a while, you will find a large amount of lint building up on the outside of the screen. If this were to build up inside the hairdryer, it would be scorched by the heating element or might even clog the motor itself. Even with this screen in place, you'll need to periodically pick lint off the screen. Too much lint can block the airflow into the dryer, and the hairdryer will overheat with less air carrying away the heat generated by the nichrome coil or other type of heating element. In the end of the hairdryer where the barrel is, is covered by a grill made out of material that can withstand the heat coming from the dryer.

I hope this helps?