Refrigeration is the process of removing heat from a substance to produce a low temperature. Heat always flows from a warmer to a cooler body or substance. Refrigeration works by placing something to be cooled near a refrigerant, something cooler that will absorb heat. Since ancient times, people have used refrigeration to help preserve food. Storage at or near 32° F (0 ° C) inhibits the growth of food-spoiling organisms and also decreases enzymes that change the texture, color, and flavor of food.

As early as 1000 b.c., the Chinese cut and stored ice. The Greeks and Romans filled cellars with mountain snow. Natural-ice refrigeration became a large-scale industry in nineteenth-century America. Entrepreneurs like Frederic Tudor harvested and shipped tons of northern pond ice to southern states and the tropics.

As cities and towns grew in both Europe and the United States during the 1800s, however, the need for...