Refrigeration
In 1000 BC, Chinese lyric collections known as the Shijing described religious ceremonies for filling and emptying ice cellars. These early structures stored snow and ice to cool beverages rather than preserve food. The ancient Greeks dug large pits insulated with grass, chaff, or tree branches to store cold air. Roman citizens used similar methods to chill their drinks during harvest seasons. Egyptians cooled water by placing shallow earthen jars on rooftops at night. Evaporation from these jars lowered the water temperature significantly. Ancient Indians applied this same evaporation concept to produce ice. Persians built underground storage pits called Yakhchal to hold ice for later use. Some historians believe the Persians were the first group to use cold storage for preserving food. In the Australian outback before reliable electricity arrived, farmers used Coolgardie safes. These boxes had hessian sides soaked in water that evaporated to cool the interior air. This method kept fruit, butter, and cured meats fresh without mechanical power.
William Cullen designed a small refrigerating machine in 1755 that created partial vacuum over diethyl ether. The boiling liquid absorbed heat from surrounding air and produced a small amount of ice. Benjamin Franklin and chemist John Hadley collaborated on an experiment at Cambridge University in England in 1758. They used volatile liquids like alcohol and ether to lower temperatures past the freezing point of water. Their thermometer bulb reached minus 14 degrees Celsius while ambient temperature stayed at 60 degrees Fahrenheit. A thin film of ice formed on the bulb surface during their trial. American inventor Oliver Evans described a closed vapor-compression cycle for producing ice by ether under vacuum in 1805. Michael Faraday liquefied ammonia and other gases using high pressures and low temperatures in 1820. Jacob Perkins built the first working vapor-compression system in 1834. His prototype operated continuously as he described in his patent application. Physician John Gorrie built a working prototype in 1842 but it failed commercially. Alexander Twining took out a British patent in 1850 for a vapour compression system using ether. Journalist James Harrison introduced commercial vapour-compression refrigeration to breweries and meat-packing houses in 1856.
Frederic Tudor harvested ice in New England and shipped it to Caribbean islands and southern states before 1830. He lost thousands of dollars initially but eventually turned a profit by constructing icehouses in Charleston, Virginia and Havana. Better insulated ships reduced ice wastage from 66% down to just 8%. Nathaniel Wyeth invented a horse-drawn ice cutter in 1825 that made harvesting faster and cheaper. Ice became a mass-market commodity by the early 1830s with prices dropping from six cents per pound to half a cent. New York City consumption increased from 12,000 tons in 1843 to 100,000 tons in 1856. Boston's consumption leapt from 6,000 tons to 85,000 tons during that same period. This created a cooling culture where most people used iceboxes to store dairy products, fish, meat, fruits, and vegetables. By the 1870s, breweries had become the largest users of harvested ice. Pollution and sewage began creeping into natural ice making it problematic for metropolitan suburbs. Public concern grew as media outlets connected diseases like typhoid fever with natural ice consumption. Ice harvesting became illegal in certain areas of the country due to these health concerns.
The Strathleven arrived at London docks on the 2nd of February 1880 carrying frozen beef, mutton, and butter from Sydney and Melbourne. William Soltau Davidson commissioned the Dunedin to be refitted with a compression refrigeration unit for meat shipment in 1881. The Dunedin sailed for London on the 15th of February 1882 marking the first commercially successful refrigerated shipping voyage. Within five years, 172 shipments of frozen meat were sent from New Zealand to the United Kingdom. Only nine shipments contained significant amounts of condemned meat. J & E Hall of Dartford, England outfitted the SS Selembria with a vapor compression system in 1886. This vessel brought 30,000 carcasses of mutton from the Falkland Islands. Refrigerated shipping led to broader meat and dairy booms in Australasia and South America. By 1900, the meat-packing houses of Chicago had adopted ammonia-cycle commercial refrigeration. Almost every location used artificial refrigeration by 1914. Major meat packers like Armour, Swift, and Wilson purchased expensive units installed on train cars and branch houses. The United States Department of Agriculture estimated that over sixty-nine percent of cattle killed in 1916 occurred in plants involved in interstate trade.
Thomas Moore patented a metal-lined butter-storage tub in 1803 which became the prototype for most iceboxes. These iceboxes remained in use until nearly 1910 without technological progress. General Electric released a household refrigeration unit powered by gas in 1911. GE invested in developing an electric model after electric companies refused to benefit from gas-powered units. In 1927, GE released the Monitor Top, the first refrigerator to run on electricity. Frigidaire synthesized Freon in 1930 creating safer refrigerators for home and consumer use. The average price of a refrigerator dropped from $275 to $154 with the synthesis of Freon. Ownership of refrigerators in American households exceeded 50% by 1940. Commercial refrigerators before this era weighed between five and two hundred tons and were unsafe. They frequently caught fire, exploded, or leaked toxic gases including methyl formate, ammonia, methyl chloride, and sulfur dioxide. Rural electrification efforts began when President Franklin D. Roosevelt signed an executive order called the Rural Electrification Administration on the 11th of May 1935. Just a few years later, 300,000 people in rural areas received power in their homes.
Refrigeration enabled new settlement patterns to emerge that were not located on natural transport channels like rivers or harbors. Cities such as Dallas, Phoenix, and Los Angeles became possible through reliable cooling technology. These galactic cities developed in areas that would have been uninhabitable just a few hundred years ago. Without cost-efficient ways to cool air and transport water and food from great distances, these large cities could never have formed. Refrigerated rail cars moved eastward from vineyards, orchards, fields, and gardens in western states to satisfy eastern markets. California specialized in growing grapes, peaches, pears, plums, and apples using refrigerated transport. Georgia became famous for its peaches while Mississippi centered its industry around tomatoes. New Mexico, Colorado, Arizona, and Nevada grew cantaloupes successfully due to refrigeration. By 1917, well-established fruit and vegetable areas close to eastern markets felt pressure from distant specialized centers. Dairy farmers could pay transportation costs and still undersell eastern competitors because of refrigeration. Large cities got their dairy supply from farms as far away as the West Coast. The United States Department of Agriculture estimated that over sixty-nine percent of cattle killed in 1916 occurred in plants involved in interstate trade.
Vapor-compression systems use circulating refrigerants like low boiling hydrocarbons or hydrofluorocarbons entering compressors as vapour. The vapor travels through condensers where it cools until condensing into liquid at constant pressure and temperature. Liquid refrigerant passes through expansion valves causing flash evaporation and auto-refrigeration of less than half the liquid. Cold liquid-vapor mixtures travel through evaporator coils and are completely vaporized by cooling warm air blown across them. Absorption cycles replaced compressors with absorbers dissolving refrigerant in suitable liquids like water-ammonia systems. These systems operate mainly where fuel for heating is available but electricity is not found. Adsorption refrigeration uses solid adsorbents such as silica gel, activated carbon, or zeolite instead of liquid absorbents. Magnetic refrigeration applies strong magnetic fields forcing paramagnetic salts like cerium magnesium nitrate to align electron shells. This process lowers entropy and releases heat absorbed by a heat sink before switching off the field. Thermoelectric cooling uses Peltier effects creating heat flux between junctions of two material types. Air cycle machines work on reverse Brayton cycles using compressed air from jet engine compressor sections. Gas turbine-powered aircraft rely heavily on these units for both cooling and pressurizing cabin environments.
Common questions
When did the ancient Chinese describe ice cellars in the Shijing?
The ancient Chinese described religious ceremonies for filling and emptying ice cellars in 1000 BC. These early structures stored snow and ice to cool beverages rather than preserve food.
Who designed a small refrigerating machine that created partial vacuum over diethyl ether in 1755?
William Cullen designed a small refrigerating machine in 1755 that created partial vacuum over diethyl ether. The boiling liquid absorbed heat from surrounding air and produced a small amount of ice.
What year did the Dunedin mark the first commercially successful refrigerated shipping voyage to London?
The Dunedin sailed for London on the 15th of February 1882 marking the first commercially successful refrigerated shipping voyage. William Soltau Davidson commissioned the ship to be refitted with a compression refrigeration unit for meat shipment in 1881.
Which company released the Monitor Top refrigerator to run on electricity in 1927?
General Electric released the Monitor Top, the first refrigerator to run on electricity, in 1927. Frigidaire synthesized Freon in 1930 creating safer refrigerators for home and consumer use.
When did President Franklin D. Roosevelt sign the Rural Electrification Administration executive order?
President Franklin D. Roosevelt signed an executive order called the Rural Electrification Administration on the 11th of May 1935. Just a few years later, 300,000 people in rural areas received power in their homes.