A clothes dryer or tumble dryer is a household appliance that is used to remove the moisture from a load of clothing and other textiles, generally shortly after they are cleaned in a washing machine.
Most dryers consist of a rotating drum called a tumbler through which heated air is circulated to evaporate the moisture from the load. The tumbler is rotated relatively slowly in order to maintain space between the articles in the load. In most cases, the tumbler is belt-driven by an induction motor.
Using these machines may cause clothes to shrink, become less soft (due to loss of short soft fibers/ lint) and fade. For these reasons, as well as environmental concerns, many people use open air methods such as a clothes line and clotheshorse.
[[Image:American Dryer Corp. laundromat dryer.JPGAmerican Dryer Corp. laundromat dryerthumbCoin-operated, gas-powered dryer found in a laundromat There are two general classes of rotating dryers: electric and gas. Both of these refer to the method used to raise the temperature of the air flowing through the tumbler, since the tumbling action is usually electrically powered.
The electric dryer generally uses a coiled wire that is heated with electric current. The amount of electric current is varied to adjust the air temperature. In the United States and Canada, where NEC and NEMA standards are in use, electric dryers typically have a 4-wire NEMA 14-30 plug, rather than the 3-wire NEMA 5-15 plug used by most appliances, and need a 30-ampere, 240-volt centre-tapped single-phase circuit. Small "portable" clothes dryers, popular with urban dwellers, normally use conventional 110 volt connections. In the rest of the world, most electric dryers in homes are somewhat smaller than those used in North America, typically with a load capacity of 5 kg (11 lb). These dryers are also easily connected to standard single-phase 240V/50Hz 10Amp powerpoints (outlets).
The gas dryer employs a gas burner that burns natural gas, propane, or butane to form a jet of hot gases that are directed into a metal heat exchanger; a fan pulls in ambient air past the heat exchanger to raise its temperature, while combustion byproducts stay separate from the heated air and are vented to the outside. The air temperature can be altered by adjusting the size of the gas flame or, more simply, by extinguishing it and relighting it under thermostat control. Gas dryers still require electricity to spin the clothes, but the amount of power needed is much less than in an electric dryer. Thus, instead of a dedicated 240-volt connection, the motors normally run on standard 120-volt electricity.
Some types of clothes dryers installed in steam-heated buildings use a steam-based system to warm the incoming air, in lieu of a electric heating element or gas-fired heater. In this case, hot steam is piped through the dryer's steam coil (a steam-capable heat exchanger) that transfers thermal energy to the incoming air. A solenoid valve at the steam inlet, controlled by the dryer, can set the temperature of the heated air simply by opening and closing it at regular intervals. Like a gas dryer, an electrical connection is still required to spin the drum, operate the steam solenoid, and power the controls.
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