Drawing: William Cullen's Design
Before mechanical refrigeration systems were introduced, people cooled their food with ice and snow, either found locally or brought down from the mountains. The first cellars were holes dug into the ground and lined with wood or straw and packed with snow and ice: this was the only means of refrigeration for most of history.
Refrigeration is the process of removing heat from an enclosed space, or from a substance, to lower its temperature. A refrigerator uses the evaporation of a liquid to absorb heat. The liquid, or refrigerant, used in a refrigerator evaporates at an extremely low temperature, creating freezing temperatures inside the refrigerator. It's all based on the following physics: - a liquid is rapidly vaporized (through compression) - the quickly expanding vapor requires kinetic energy and draws the energy needed from the immediate area - which loses energy and becomes cooler. Cooling caused by the rapid expansion of gases is the primary means of refrigeration today.
The first known artificial refrigeration was demonstrated by William Cullen at the University of Glasgow in 1748. However, he did not use his discovery for any practical purpose. In 1805, an American inventor, Oliver Evans, designed the first refrigeration machine. The first practical refrigerating machine was built by Jacob Perkins in 1834; it used ether in a vapor compression cycle. An American physician, John Gorrie, built a refrigerator based on Oliver Evans' design in 1844 to make ice to cool the air for his yellow fever patients. German engineer Carl von Linden, patented not a refrigerator but the process of liquifying gas in 1876 that is part of basic refrigeration technology.
Refrigerators from the late 1800s until 1929 used the toxic gases ammonia (NH3), methyl chloride (CH3Cl), and sulfur dioxide (SO2) as refrigerants. Several fatal accidents occurred in the 1920s when methyl chloride leaked out of refrigerators. Three American corporations launched collaborative research to develop a less dangerous method of refrigeration; their efforts lead to the discovery of Freon. In just a few years, compressor refrigerators using Freon would became the standard for almost all home kitchens. Only decades later, would people realize that these chlorofluorocarbons endangered the ozone layer of the entire planet.
History of Sealed Refrigeration Systems
One hundred years ago, refrigeration engineers began to search for a permanent solution to the problem of leaky refrigeration systems.
The History of the Refrigerator
From the History Channel, a cool, simple outline of the "History of the Refrigerator".
"At some point, perhaps in fourteenth century China or seventeenth century Italy, it was discovered that the evaporation of brine (salt water) absorbed heat and therefore a container placed in brine would stay cold." This short essay discusses the highlights of refrigerator history.
A mixture called chemogene (consisting of petrol ether and naphtha) was patented as a refrigerant for vapor compression systems in 1866. Carbon dioxide was introduced as a refrigerant in the same year.
Refrigerators - The Physics Handbook
The term "refrigerator" was coined by a Maryland engineer, Thomas Moore, in 1800. Moore's device would now be called an "ice box" -- a cedar tub, insulated with rabbit fur, filled with ice, surrounding a sheetmetal container for transporting butter from rural Maryland to Washington, DC.
How Refrigerators Work
How Refrigerators Work, written by Marshall Brain of How Stuff Works.
The Refrigeration Research Museum (1890 - 1960)
Who invented the refrigerator? When was it invented?
The Freezing Process
Freezing food involves lowering its temperature to below 0º C, resulting in the gradual conversion of the water present in the food into ice.
Ice Cube Trays
The history of ice cube trays.