The Advent of Mechanical Refrigeration Alters Daily Life and National Economies throughout the World

views updated

The Advent of Mechanical Refrigeration Alters Daily Life and National Economies throughout the World

Overview

People have taken advantage of natural refrigeration for thousands of years. Caves, holes dug in the ground, springs, ice and snow, and evaporative cooling have all been used to cool food and drinks. Natural refrigeration, however, has limitations. Its availability depends on location and weather conditions, and it has never been adequate to chill large quantities for long periods of time. The scientific study of thermodynamics and chemistry that began in the seventeenth century, accompanied by advances in manufacturing technology, led to the birth of the mechanical refrigeration industry in the nineteenth century.

Background

An Egyptian fresco from 2500 b.c. shows slaves fanning water jars, an early record of human efforts at cooling. The people of ancient Egypt and India knew how to make ice by exposing jars of water to the clear night air. While both societies credited supernatural forces for this phenomenon, it was a combination of evaporative cooling through the porous jars and radiational cooling into the night sky that chilled the water and froze its surface.

A Chinese poem to the Great One of Cold written around 1175 b.c. describes harvesting ice and storing it in a cave. One thousand years later ancient Greeks and Romans collected snow from the mountains and kept it in pits covered with straw and branches. Wealthy Romans used snow to chill water and wine and for cold baths called frigidaria. Alexander the Great had thirty pits filled with snow so that his troops could drink cold wine during the siege of the Indian capital of Petra.

Chilling preserves food by slowing both the growth of harmful microorganisms and the rate of metabolism and cellular respiration of the food. Long before this relationship was understood, there is evidence that Iron Age (beginning in Europe and the Middle East c. 1200 b.c.) communities stored food underground. The low temperature and humidity in caves maintained the freshness of seeds and grains while preventing losses from mold, fungus, and insects. Before mechanical refrigeration crops such as potatoes, apples, and cassava were often stored underground or in aboveground structures covered with straw and soil where they stayed fresh for as long as six months.

It has been known since antiquity that certain chemicals lower the temperature of water or snow. Chemical refrigeration was not common until the 1500s, however, when it became fashionable for the Italian nobility to chill wine in a solution of water and saltpeter (ammonium nitrate). Later that century British scientist Francis Bacon (1561-1626) furnished the royal family with ice by mixing saltpeter and snow. Robert Boyle (1627-1691), one of the founders of thermodynamics, also studied various salts as freezing agents and the effect of cold on animals, vegetables, and minerals. His Experimental History of Cold was the first scientific study of refrigeration.

As experimentation with chemical refrigeration continued during the eighteenth century, the invention of the mechanical pump and thermometer provided the technology for new areas of research. William Cullen (1710-1790), a professor of medicine in Scotland, found that evaporative cooling increases in a vacuum and that volatile liquids like ether produce even lower temperatures. Edward Nairne (1726-1806) and John Leslie (1766-1832) discovered that sulfuric acid absorbs water vapor, an effect that produces cold. John Dalton (1766-1844) observed that air cools or heats its surroundings depending on whether it is expanding or contracting. These and other experiments were the foundation of mechanical refrigeration in the nineteenth century.

Before mechanical refrigeration became practical, the first half of the nineteenth century saw the rise of the natural ice industry. Norway was a major exporter of ice, sending large quantities to Europe and England. In the United States Frederic Tudor (1783-1864) built a business that eventually shipped ice to every major port in South America, Asia, and Australia. The demand for ice grew with the century, boosted by the brewing industry in the 1860s. By 1872 the United States exported 220,000 tons of ice a year. A specialized technology for harvesting and storing ice arose, including circular ice saws, ice houses, and iceboxes for homes and businesses. Artificial ice began to overtake natural ice in the 1890s as water near cities became polluted. An unusually mild winter in 1890 emphasized the unreliability of natural ice. At the same time, mechanical refrigeration was increasingly adopted for ice making, cold storage, and breweries.

Two types of refrigeration machines evolved during in the nineteenth century. The first worked by compressing either air or a vapor such as ethyl ether and ammonia. When the air or vapor expanded again, it produced cooling. The first vapor-compression system was invented by Oliver Evans (1755-1819), who published a theoretical description of a closed vapor-compression machine in 1805 but renounced his rights to the invention. In 1834 his friend Jacob Perkins (1766-1849) took out an English patent on Evans's design, which was used to build the first ice-making machine.

John Gorrie (1803-1855), a Florida physician, invented the air-compression refrigerator in 1844 because he believed that heat and humidity were responsible for "...the mental and physical deterioration of the native inhabitants...." He used his machine to make ice and cool the bedrooms of his malaria and yellow-fever patients. Gorrie's ultimate goal was to cool entire cities, but he was unable to obtain financial backing for his ice-making machine and died disappointed and in debt.

Apparently without knowledge of these earlier designs, the American engineer Alexander Twining (1801-1884) began experimenting with ether evaporation and condensation in 1848. He built a prototype freezing machine in 1850 and opened the first commercial ice-making plant using vapor refrigeration five years later. His attempt to open a second plant in New Orleans was stymied by the Civil War (1861-65), which gave his rivals, Ferdinand Carré (1824-1894) and W. James Harrison (1816-1893), the opportunity to gain a foothold in the southern states.

Charles Piazzi Smyth (1819-1900) shared Gorrie's belief in the need for mechanical cooling in hot climates, particularly in the hospitals of India that he visited for the British government. Around the same time as Gorrie, Smyth designed and built a compressor that could be powered by humans or oxen on a treadmill. Air-cycle compression systems were further advanced in the 1860s by Alexander Kirk (1830-1892), who installed ice and refrigeration machines throughout the British empire. Air-cycle refrigeration systems, the predominant design for ships and hospitals until the 1890s, had relatively low thermal efficiency. However, air, unlike ether and ammonia, was free, non-toxic, non-flammable, and always available.

W. James Harrison began experimenting with vapor-compression refrigeration in 1854 after studying the patents of Perkins, Gorrie, and Twining. He moved from Australia to England, where he worked with the engineering firm Siebe & Company on the production of a refrigeration machine. The first models were sold to a brewery and a petroleum company. His next goal was to export frozen Australian meat. After years of failure and bankruptcy, Harrison finally achieved success with Thomas Mort (1816-1878) and Eugène Nicolle (1824-1895?), owners of the Fresh Food and Ice Company in Sydney.

One of the earliest successful pioneers in commercial liquid-vapor refrigeration in the United States was David Boyle (1837-1891). Boyle saw the potential in refrigeration after making $8,000 selling cold lemonade. Unable to buy a satisfactory machine, he designed his own ammonia-compression system in 1873, a design that was manufactured until 1905.

Breweries, which require cool temperatures for fermentation and storage, greatly increased the market for refrigeration in the second half of the nineteenth century. Carl von Linde (1842-1934) brought a rigorous scientific approach to the design and construction of brewery refrigeration systems. After studying the thermodynamics of refrigeration, he built a machine with double the efficiency of existing plants. He then patented his design, which was installed in breweries in Germany, Great Britain, and the United States.

The second type of refrigeration, aqua-ammonia absorption, grew out of experiments by Edward Nairne (1726-1806), John Leslie (1766-1832), and John Vallance (1801-1850) in which they used sulfuric acid to absorb water. Edmund Carré (1822-1890?), the first to commercialize the absorption method, sold ice-making machines to several French cafes in the 1850s. His brother Ferdinand, who went on to obtain more than 50 patents in the field of refrigeration, improved the method by switching from acid to ammonia. Two ammonia absorption machines that were smuggled into southern ports during the Civil War became the prototypes for absorption refrigeration machines throughout the United States. In 1877 Edmund Carré installed one of his brother's machines in a steamer that carried sheep carcasses from Buenos Aires, Argentina, to Marseilles, France.

Daniel Holden (1837-1924) improved one of Carré's original machines by making ice with distilled water instead of river water. The result was crystal-clear ice, an important attraction for customers. Holden built both absorption and compression plants and patented a combination of the two in 1877.

By the end of the century 400 aqua-ammonia absorption plants had been built, mostly in the southern United States. They were thermo-dynamically suited for ice making, but less so for cold storage and shipboard refrigeration. Absorption plants, as well as air-cycle machines, lost favor once high-efficiency engines for ammonia compression plants were invented in the 1890s.

Impact

The development of refrigeration during the nineteenth century propelled scientific and technological progress in related fields. Advances were made with refrigerants, insulating materials, refrigerated boxcars, steamships, warehouses, and compressors. Because refrigeration was a competitive and potentially profitable business, the drive for improvements was constant, culminating in the development of small home refrigerators at the turn of the century.

Refrigeration also had an immediate impact on people's lives. Instead of spoiling during seasonal gluts, food could be refrigerated and consumed out of season. Properly refrigerated or frozen food was less likely to carry disease-causing bacteria. Even the kind of food people ate changed. Former delicacies such as cold drinks, ice cream, and imported meat and fish became more widely available. A dependable supply of ice also made life in hot climates more comfortable.

Refrigeration was a factor in the continued growth of urban centers in Europe and the United States whose populations depended on the dairy products, meat, and produce brought to them by refrigerated boxcars and steamships. Refrigeration was also fundamental to the meat-exporting economies of Australia, New Zealand, and Argentina.

LINDSAY EVANS