The idea of using a low-temperature environment to prevent food spoilage has been around for centuries. The creation of the familiar home appliance resulted from a series of innovations by chemists, engineers, and inventors over the span of the 18th and 19th centuries. The American inventors Oliver Evans, Jacob Perkins, and John Gorrie are credited with developing the earliest versions of the modern refrigerator in the early 1800s. Later that century, the work of German engineer Carl von Linden allowed chemical refrigerant to be stored efficiently, paving the way for mass production of refrigerators.
Early Efforts at Food Preservation
Human cultures have long known that cold temperatures can protect valuable foodstuffs from bacteria and other factors that may render them inedible. Preservative methods such as salting and drying were also effective, but these were not well suited to all kinds of food. Before mechanical refrigeration was widely available, many cultures used well-insulated buildings called icehouses for food storage, using winter ice and snow as natural coolants. These structures date to the second millennium BC in Europe and Asia, and the names of the engineers who designed them have been lost to history.
The First Refrigerators
Icehouses were used well into modern times, particularly in rural areas where electricity and appliances were expensive or unavailable. In the early 1800s, American engineer Thomas Moore created a home version of the icehouse, a portable insulated chamber cooled by block ice. Moore coined the term "refrigerator" to describe his invention, although it came to be more commonly known as the "icebox." Iceboxes had the same general shape and function as modern-day refrigerators and some people still use this name. In many areas, a local delivery person, colloquially known as an "iceman" in the U.S., would bring fresh ice blocks to neighborhoods in a cart or truck.
In the 1750s, Scottish physicist William Cullen discovered that some chemical reactions would draw heat away from a particular area, creating a pocket of cold. Cullen, unconcerned with the practical applications of his discovery, did not realize he had found the basis for modern refrigeration. Around the same time that Thomas Moore invented the icebox, Oliver Evans designed, but did not build, a machine to make use of Cullen’s chemical process. It was not until 1834 that scientist Jacob Perkins built and patented the first functioning refrigerator. Perkins, a major figure in American engineering, also tinkered with heating and cooling systems for the home and is sometimes called the father of refrigeration.
Ten years later, U.S. physician John Gorrie was seeking a steady source of ice to lower the body temperature of patients suffering from yellow fever. The ice delivery methods common at the time were insufficient for his purposes so, working from Evans’ original design, he built a refrigeration unit that was more practical and efficient than the one created by Perkins. This was the model for the modern refrigerator. As a result, Evans, Perkins, and Gorrie can effectively share credit for this now-essential device.
The Refrigeration Process
Mechanical cooling systems depend on chemicals called refrigerants. As the refrigerant moves through the appliance, it is compressed, which raises its temperature. That heat is released from the back of the refrigerator; as the heat is dissipated, the refrigerant condenses but stays at that high pressure. The refrigerant then moves through an expansion valve, where the pressure drops and it turns back into a gas. As it changes from liquid to gas, its temperature falls, cooling the air. Fans and motors circulate this cooled air within an insulated area.
The first refrigerators used liquid refrigerants like ether, but in 1876, Carl von Linden discovered an improved method of liquefying gas. This made the mass production of refrigeration devices practical, paving the way for their widespread sale and use in the 20th century.
There were still severe problems with the design, however. Early refrigeration units used highly toxic gases such as ammonia, sulfur dioxide, and methyl chloride. The chambers containing these gases sometimes leaked, resulting in several fatal home accidents in the early 1900s. Appliance manufacturers realized that a safer cooling element was needed, which led to the discovery of synthetic refrigerants called chlorofluorocarbons (CFCs). Also known collectively as Freon®, they became the standard refrigerant worldwide in the decades that followed.
Freon® was not a perfect solution either, however. In the 1970s, scientists discovered that CFCs contribute to the depletion of the Earth’s natural ozone layer. Ozone depletion, which increases the damaging health effects of solar radiation, was soon understood as a major environmental crisis. World governments banned the use of CFCs in the 1980s, although it would be decades before all the devices that employed them would be out of service. Modern refrigerators use safer alternative refrigerants, and their highly efficient machinery typically requires smaller amounts of chemicals than were used by older units.