A refrigerator consists a thermally insulated compartment and a heat pump that transfers heat from the inside of the fridge to its external environment so that the inside of the fridge is cooled to a temperature below the ambient temperature of the room. A refrigerator maintains a temperature a few degrees above the freezing point of water. Optimum temperature range for storage of perishable foods is 3 to 5 degree centigrade (37 to 41 degree F). A similar device that maintains a temperature below the freezing point of water is called a freezer.
|Today, most refrigerators are frost-free. They have automatic defrosting systems so that you don't have to take everything out of your refrigerator and allow it to warm up so you can melt built-up ice in the freezer. An automatic defrost system includes a timer, a limit switch, and a heater, which melts away frost.|
1748: The first known artificial refrigeration was demonstrated by William Cullen at the University of Glasgow.
1805: The American inventor Oliver Evans, acclaimed as the "father of refrigeration," invented the vapour-compression refrigeration machine.
1834: Jacob Perkins modified Evans' original design, building the world's first refrigerator. He filed the first legal patent for refrigeration using vapour-compression.
1856: Australian James Harrison, an immigrant from Scotland, developed an ice making machine using ammonia and an ether compressor.
1918: Kelvinator Company introduced the first refrigerator with any type of automatic control.
1827: The first refrigerator to see widespread use was the General Electric "Monitor-Top" refrigerator.