Refrigeration is a technology that's often overlooked but has had a huge impact on modern life. It's greatly improved human health by not only preserving foods from spoilage but also by allowing nutrient-rich foods to be shipped to markets where they were previously unavailable. It is of course also responsible for wonderful phenomena like West Palm Beach air conditioning. Hey, air conditioning repair men have to eat too right? But while comparatively unreliable techniques existed in previous centuries to generate lower temperatures, mechanical refrigeration made it possible to produce cold temperatures whenever and to whatever degree was desired. Groundwork While ancient civilizations like Egypt and India understood something about evaporative cooling, it was in the mid-18th century that experimenters discovered the basic rules of how this worked. Benjamin Franklin, while at Cambridge University in the 1750s, assisted Professor John Hadley in dropping the temperature of a thermometer nearly 60 degrees Fahrenheit by coating it with ether and blowing air across it. In the same decade, William Cullen discovered, using Amonton's Law of Pressure-Temperature, that lowering the pressure of ether in a container would produce a lower boiling point and allow it to absorb heat from its surroundings. Up And Running Using these basic experiments, an American, Oliver Evans, created plans for a mechanical system that utilized both compression and decompression to greatly lower the temperature of a gaseous working fluid. In 1805, he described how ether could be first pressurized to raise its temperature. It would then cool while still under pressure. Finally, its pressure would be lowered. This would cause even further heat loss when it passed through an evaporator. When this happened, it would pull heat from the surrounding area and refrigerate it. This basic blueprint was turned into an actual machine by inventor Jacob Perkins in 1834. The attempt worked but was a business failure. Dr. John Gorrie made another unsuccessful device in 1842 but his goal was to air condition a room.
Impact Building on these initial tries, others in the 1850s, like James Harrison, Ferdinand Carre, and Carl Von Linde, developed more efficient versions that used ammonia or methyl chloride in place of ether. These mechanical refrigerators caught on and revolutionized commercial food storage and shipping throughout the remainder of the 19th century. In 1911, General Electric introduced the first home refrigerator. By 1930, two major changes made consumer refrigerators highly practical. First, an electric motor replaced the gas motor. Second, chlorofluorocarbon or CFC replaced poisonous ammonia as the working fluid. The introduction of CFC allowed refrigerators to become much more affordable and their popularity exploded.