Refrigeration

• 1. Introduction

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  Benjamin Franklin once wrote, "From this experiment, one may see the possibility of freezing a man to death on a warm summer's day." He wrote it in 1758, after he and a chemist named John Hadley dripped ether and alcohol onto the bulb of a mercury thermometer at Cambridge University. With a bellows they hurried the evaporation along. The ambient air sat at 65 degrees Fahrenheit. The thermometer bulb fell to 7. A thin film of ice grew across the glass. That was refrigeration in its infancy: the artificial removal of heat from one place and its release somewhere warmer. The principle sounds simple. The consequences were not. How did a parlor experiment with ether become the reason cities like Houston and Las Vegas could rise in places once thought uninhabitable? How did frozen sheep cross an ocean and remake an entire nation's economy? And before any machine existed, how did people chase the cold at all? Those questions begin not in a laboratory, but in ancient ice cellars and snow pits.

• 2. Chasing The Cold

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  Earlier than 1000 BC, people were already harvesting snow and ice by the season. A Chinese collection of lyrics from that era, the Shijing, describes religious ceremonies for filling and emptying ice cellars, though little is known about how those cellars were built or what the ice was for. The Tang dynasty, around 618 AD, scraped saltpetre from walls to make ice in summer. The book of Proverbs offers a line about "the cold of snow in the time of harvest," which historians read as the Jews cooling beverages rather than preserving food. Greeks and Romans dug large snow pits and insulated them with grass, chaff, or tree branches, and they too used the chill mostly for drinks. Egyptians set shallow earthen jars of water on their roofs at night and let evaporation do the cooling, a trick the ancient people of India used to make ice. The Persians took a different path. They stored ice in a pit called a Yakhchal, and may have been the first people to use cold storage to preserve food rather than merely chill a cup. Centuries later in the Australian outback, before reliable electricity, farmers built the Coolgardie safe: a box frame with hessian sides soaked in water, where evaporation kept fruit, butter, and cured meats. The same evaporating film of water that fascinated Franklin had been quietly serving households for thousands of years.

• 3. The Ice Trade

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  Before 1830, few Americans bothered to refrigerate their food, simply because ice-storehouses and iceboxes were scarce. Frederic Tudor saw a fortune in that gap. He harvested ice in New England and shipped it to the Caribbean islands and the southern states, losing thousands of dollars at first before turning a profit. Tudor built icehouses in Charleston, in Virginia, and in the Cuban port of Havana, and paired them with better-insulated ships. Together those improvements cut ice wastage from 66 percent down to 8, which encouraged him to open markets in New Orleans and Savannah. One of his suppliers, Nathaniel Wyeth, invented a horse-drawn ice cutter in 1825, making the harvest faster and cheaper and drawing rivals into the trade. By the early 1830s ice had become a mass-market commodity, its price falling from six cents a pound to half a cent. The numbers in the cities tell the rest. New York's ice consumption climbed from 12,000 tons in 1843 to 100,000 tons in 1856, and Boston's leapt from 6,000 tons to 85,000 in the same stretch. People packed their dairy, fish, meat, and even fruits and vegetables into iceboxes, building what one might call a cooling culture, the habit of cold that would soon welcome machines that made ice without any winter at all.

• 4. Inventing The Machine

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  William Cullen designed a small refrigerating machine in 1755, using a pump to pull a partial vacuum over a container of diethyl ether. The ether boiled, drew heat from the surrounding air, and even produced a little ice, but it had no practical use. Oliver Evans described a closed vapor-compression cycle for making ice by ether under vacuum in 1805. Michael Faraday liquefied ammonia and other gases with high pressure and low temperature in 1820. The breakthrough toward something that ran continuously came in 1834, when Jacob Perkins built the first working vapor-compression refrigeration system in the world. His patent promised volatile fluids that could cool or freeze while being "constantly condensing" and brought back into operation "without waste." The prototype worked but never sold. John Gorrie, a physician, built his own prototype in 1842, convinced that tropical heat bred mental decline and diseases like malaria, and that cooled air in homes and hospitals could prevent illness; his machine was a commercial failure too. Carl von Linde, a professor at the Technological University of Munich, took up refrigeration in the 1860s and 1870s because brewers wanted year-round lager. He patented an improved way of liquefying gases in 1876, opening the door to ammonia, sulfur dioxide, and methyl chloride as refrigerants used until the late 1920s. The journalist James Harrison turned theory into trade, building a mechanical ice-making machine in 1851 on the banks of the Barwon River at Rocky Point in Geelong, Victoria, and bringing vapour-compression refrigeration into breweries and meat-packing houses, a dozen systems running by 1861.

• 5. Frozen Across The Sea

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  On the 2nd of February 1880, the Strathleven reached the London docks carrying frozen beef, mutton, and butter from Sydney and Melbourne. That cargo proved frozen goods could survive an ocean crossing, yet the breakthrough is usually credited to William Soltau Davidson, an entrepreneur who had emigrated to New Zealand. Davidson believed Britain's rising population and hunger for meat could offset the slump in world wool markets crushing New Zealand. He had the Dunedin refitted with a compression refrigeration unit in 1881, and on the 15th of February 1882 the ship sailed for London on the first commercially successful refrigerated voyage. The Times called it "such a triumph over physical difficulties, as would have been incredible, even unimaginable, a very few days ago." The trade exploded. The Dunedin's sister ship Marlborough converted the next year, a rival vessel named Mataurua joined in, and the German steamer Marsala began carrying frozen New Zealand lamb in December 1882. Within five years, 172 shipments of frozen meat crossed from New Zealand to the United Kingdom, with significant amounts condemned in only 9 of them. In 1886, J and E Hall of Dartford fitted the SS Selembria with a vapor compression system to bring 30,000 carcasses of mutton from the Falkland Islands. Canterbury soon supplied half of New Zealand's exported sheep carcasses, its farmers improving feed until sheep were ready for slaughter in just seven months.

• 6. Into The Home

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  Thomas Moore patented a metal-lined butter-storage tub in 1803, and it became the prototype for most iceboxes. Those boxes stayed in use until nearly 1910, the technology barely changing, so that a consumer in 1910 faced the same moldy, stinky icebox his grandparents had endured. Commercial refrigeration could not simply move indoors. Some units in use in 1910 weighed between five and two hundred tons, and others ran from five to two hundred. They were expensive to build, buy, and maintain, and they were dangerous, prone to catching fire, exploding, or leaking toxic gases. General Electric was among the first to clear these hurdles. In 1911 it released a household unit powered by gas, which dropped the size by removing the need for an electric compressor motor. Because GE's electric-company customers gained nothing from a gas model, the firm built an electric one, and in 1927 released the Monitor Top, the first refrigerator to run on electricity. Then in 1930 Frigidaire, one of GE's main competitors, synthesized Freon, a refrigerant built largely on chlorofluorocarbon chemistry. Freon made refrigerators smaller, lighter, and cheaper, dropping the average price from 275 dollars to 154, and pushing ownership in American households past 50 percent by 1940. The compounds were meant to be safer than ammonia, methyl chloride, and sulfur dioxide. In the 1970s, though, scientists found CFCs were reacting with atmospheric ozone, and the Montreal Protocol of 1987 curtailed their use worldwide.

• 7. Cities Without Rivers

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  Lewis Mumford coined the term "galactic city," while Joel Garreau coined "edge city," both describing business, shopping, and entertainment clustered far from any traditional downtown. Such cities, Los Angeles, Las Vegas, Houston, and Phoenix among them, share an odd trait: they sit on no natural channel of transport, no harbor or river or valley crossroad that historically dictated where people settled. A few hundred years ago their sites would have been uninhabitable. They became possible through reliable automobiles, highway systems, refrigeration, and a surge in agricultural production. The link to the farm ran along the refrigerated rail car, which turned a regional market into a national one. The beef packing industry pushed first for refrigerated cars, and railroad companies resisted, slowed by their heavy investments in cattle cars, stockyards, and feedlots, and by the cars' cost and complexity. Once adopted, the beef packers dominated the business by controlling ice plants and icing fees. The Department of Agriculture estimated that in 1916, over 69 percent of cattle killed in the country died in plants tied to interstate trade. California's refrigerated carloads rose from 4,500 in 1895 to between 8,000 and 10,000 in 1905, as the state specialized in grapes, peaches, pears, plums, and apples. Georgia became famous for peaches, Mississippi for tomatoes, and large cities drew their dairy from farms as far as 400 miles away. By the 1960s the interstate highway system was complete enough that trucks carried most perishable loads, pushing the old refrigerated rail cars aside.

• 8. Cycles And Salts

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  Sadi Carnot described the operating principle of the refrigeration cycle mathematically in 1824, treating it as a heat engine. Most systems today run the reverse-Rankine vapor-compression cycle, the same one found in household refrigerators and in large commercial and industrial plants. A refrigerant enters the compressor as vapor, is compressed at constant entropy, then flows through the condenser, where it cools and condenses into a liquid by shedding heat. Passing through an expansion valve, its pressure drops abruptly, flash-evaporating less than half the liquid into a cold mixture that vaporizes again in the evaporator while a fan blows warm air across the coil. Not every method works this way. Non-cyclic refrigeration cools by melting ice, sublimating dry ice, or evaporating liquid nitrogen, with dry ice reaching as low as 195 kelvin. Thermoelectric cooling uses the Peltier effect across the junction of two materials, common in camping coolers and cooled image sensors despite its low efficiency. Magnetic refrigeration, or adiabatic demagnetization, exploits the magnetocaloric effect in a paramagnetic salt such as cerium magnesium nitrate, though it remains limited to cryogenics and research. Newer still is elastocaloric cooling, where super elastic materials heat under stress and absorb heat when released; nitinol outputs about 66 joules per cubic centimeter with a temperature change near 16 to 20 kelvin, while natural rubber manages roughly 12. Among all these applications, one of the most influential was the rise of the sushi and sashimi industry in Japan, where the Kyoto-based Zojirushi corporation made refrigerators cheaper and more accessible around mid-century.