Clothes dryer

A clothes dryer or tumble dryer (also spelled drier) is a major household appliance that is used to remove the residual moisture from clothing and other textiles, generally shortly after they are cleaned in a washing or washing/drying machine.

Most dryers consist of a rotating drum through which heated air is circulated. The hot air removes the moisture from the fabric through evaporation. The drum is rotated relatively slowly in order to create a tumbling effect. In most cases, the drum is belt-driven by an induction motor. Spin dryers use centrifugal force to extract water from clothes and are energy efficient.

There are generally two 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 drum.

Electric dryers

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, 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 centertapped single-phase circuit.

Gas dryers

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 venturi chamber, which uses Bernoulli's principle to pull in ambient air and raise its temperature. The air temperature can be altered by adjusting the size of the gas flame or, more commonly, by merely extinguishing it and relighting it.

Condenser dryers

Condenser dryers are ventless and are usually electric. A heat pump works as a dehumidifier to extract moisture. Condenser dryers generally have smaller capacity and longer drying times than vented dryers, due to lower operating temperatures. Models exist which combine a washing machine and a dryer.

Spin dryers

Spin dryers use centrifugal force to extract water from clothes. They extract more water in two minutes than a gas or electric drum dryer can in twenty saving significant amount of energy. However, they will not completely dry the clothes and must be used with a conventional dryer or clothesline.

Static

Clothes dryers can cause static cling, through the triboelectric effect.

History

Contrary to Internet rumors, the first tumble dryer was not invented by American George T. Sampson. A hand-cranked version was created in 1799 by a Frenchman named Pochon. Sampson's United States patent (number 476,416), which he received on June 7, 1892, was for an improved rack for holding wet clothes near a heat source. Electric tumble dryers appeared in the 20th century.

Ecology

Energy Star, a United States government program concerned with energy efficiency in consumer products, does not rate clothes dryers, because most clothes dryers marketed in the U.S. consume similar amounts of energy.

External links

Online Dryer Repair Manual
How Dryers Work Article by HowStuffWorks.com
^* The History of Washing Machines and Clothes Dryers
^* Electricity Consumption, Cost, and CO2 Emissions of Appliances & Widgets
^* Energy Star site on clothes washers and dryers
^* Clothes Dryer Safety Secrets
^* Centrifugal Clothes Dryer: Spin-X

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