# Inside a Tumble Dryer By Zara Topic: Machines [Open the interactive Jig](https://ask.jig.com/j/PL0JkFXKufVa) ## Guide ### 1. Inside a tumble dryer A tumble dryer dries clothes by evaporation: water in the fabric becomes water vapour, a gas, and warm moving air carries it away\. This condenser dryer turns the vapour back into water in a tank\. Tap the door, dial, tank or basket, or drag to turn it\. A generic 7\-8 kg dryer, about 60 cm wide and 85 cm tall, not a particular brand\. ### 2. Load the damp laundry Even after a fast spin in the washing machine, cotton still holds roughly half of its own dry mass in water\. Load the clothes loosely: a drum about half full lets warm air reach every surface\. 4 kg of dry cotton can hold about 2 kg of water, which is 2 litres for the dryer to remove\. ### 3. Clean the lint filter Lint is the loose fibres that rub off clothes as they tumble\. The lint filter is a fine mesh at the bottom of the door opening that catches them before they reach the fan and the heater\. A blocked filter slows the airflow, so drying takes longer and uses more energy\. Lint burns easily\. Clean the filter after every load to lower the risk of fire\. ### 4. Choose a programme Cotton can take hotter air than synthetic fibres such as polyester, which can shrink or crease when they get too hot\. Turn the dial to pick a programme; the display shows the air temperature and an estimated drying time\. Tap the dial to step round, or drag it\. The temperatures and times are typical values\. ### 5. Press Start A door switch checks that the door is shut; if it opens, the heater and motor stop\. The motor turns the drum through a long rubber belt wrapped round the outside of the drum, and the same motor spins the fans\. Tap the Start button on the panel\. The motor pulley is much smaller than the drum, so the motor turns about 27 times for each turn of the drum \(an estimated ratio\)\. ### 6. Heat and tumble The fan pushes air past the heating element, a coil of wire that gets hot when an electric current flows through it, and warms the air to about 70 °C\. The hot air enters through holes in the back of the drum\. The drum turns at about 50 rpm, and its ribs, called baffles, lift the clothes and drop them through the air stream\. Evaporating 1 kg of water takes about 2\.3 MJ of energy, its latent heat of vaporisation\. The drum turns slowly on purpose: above about 60 rpm the clothes would cling to the wall instead of falling\. ### 7. Condense the vapour Warm humid air, meaning air carrying a lot of water vapour, leaves the drum through the lint filter and flows into the condenser, a heat exchanger cooled by room air from a second fan\. As the air cools, the vapour condenses back into liquid water\. A small pump lifts the water up to the tank, and the drier air goes back to the heater to be used again\. This air goes round in a closed loop\. A vented dryer blows its humid air outside through a hose instead\. ### 8. Sense, cool down, finish Two metal sensor bars in the drum mouth touch the tumbling clothes\. Wet fabric conducts electricity much better than dry fabric, so the controller can tell when the load is dry and switch the heater off\. The drum keeps turning in cool air for a few minutes to reduce creases, then the dryer beeps\. Empty the water tank after each load: tap the tank at the top left\.