Refrigeration

heat · machines · cold · technology

Moving heat around. Refrigeration works by taking heat from a cold space (like inside your fridge) and pushing it to a warmer place (like your kitchen). It's like moving something uphill against gravity, except with invisible heat energy.

Ancient vs. modern. Long ago, people used ice and dry ice to keep food cold, but that ice would eventually melt. Today's refrigerators use special liquids and pumps that keep cooling forever without needing new ice.

The refrigerant secret. Modern fridges use a special cooling liquid that changes between liquid and gas. As it changes back and forth, it absorbs heat from inside the fridge and releases it outside, keeping your food fresh.

Many ways to cool. Refrigeration can work through electricity, heat pumps, magnets, and even lasers. Most refrigerators use electricity to power a compressor that squeezes the cooling liquid.

Cool stuff it does. Refrigeration isn't just for kitchen fridges. It keeps food in stores frozen, helps scientists study super-cold materials, cools buildings with air conditioning, and even keeps medicine safe.