The refrigerator is an important instrument of food preservation for modern society. The refrigeration cycle is the chemical process that drives the refrigerator and generally consists of four main steps: 1) compression of ammonia refrigerant; 2) cooling of ammonia refrigerant; 3) expansion of ammonia refrigerant; and 4) drawing in of heat from the core of the refrigerator. Many variations on this process exist as manufacturers find new ways to improve the temperature-control aspects of the refrigerator.
Introduction Chances are, he's in your house right now. He's big. He's cold. And he knows where you keep your food. As a matter of fact, he is where you keep your food. He's your refrigerator. And he's in for a surprise.
Refrigerators have been a hallmark of American family life in recent decades. Today, a century after the refrigeration cycle revolutionized the concept of food storage, the refrigerator is gearing up for a makeover. Modern science and engineering principles are combining in the latest refrigerators, and they're on their way to a kitchen near you in the not-too-distant future.
From the Cave to the Kelvinator Although it is nearly impossible to fathom now, modern refrigeration was not a part of daily family life until the 19th century. Prior to today's beloved, compact steel boxes, people stored food in the coldest places they could find or make. Ancient Greeks, Romans, and Hebrews covered the food they wanted to keep cold with snow, and topped it off with an insulating material to keep the heat out and the cold in. The Chinese harvested and stored ice before even the first millennium (Krasner-Khait). Many other pre-industrial societies stored food below ground, in cellars and wells (Refrigeration).
The pioneers' rudimentary but effective cold spaces incorporated the most important part of the modern refrigerator: the refrigerant, the substance that circulates through the refrigerator to make the food cold. For these early, underground "refrigerators," the refrigerant was water. The "refrigerator" would be a small room or chamber with water trickling down the walls by means of small holes. Pioneers also employed a variation on this technique by building a "springhouse", a small house over a spring. They placed buckets of cream and butter into the naturally running water to keep their content cold (Refrigeration). Unfortunately, these methods were not without their shortcomings; food often spoiled anyway and many unfortunate pioneers fell victim to "summer complaint," a sickness obtained from the bacteria of spoiled food (Krasner-Khiat).
In the mid 19th century, Frenchman Ferdinand Carre devised a more recognizeable form of the modern refrigerator. Carre began experimenting with the concept of circulating a coolant around a core (Ideafinder). In his "vapor-compression refrigeration system," an instrument called a compressor circulated ammonia around the cool core of the system. Carre's system became popular, but ultimately proved too large, expensive, and dangerous to become a real household item. Many continued to rely on iceboxes (Roger's).
Raoul Pictet of Switzerland and Karl von Linde of Germany both modified Carre's design to produce more practical refrigerators (Ideafinder). The first domestic refrigerator entered the scene in 1913 thanks to Chicago's Fred W. Wolf, Jr. He coined his machine the "Domelre," short for Domestic Electric Refrigerator. Wolf's invention met with little success. The subsequent Kelvinator was more widely sold, but General Electric's 1927 "Monitor Top" refrigerator won the early refrigerator popularity contest. The company produced over 1,000,000 units, some of which still function today (Refrigerator). What Is In Store For Refrigerators This vapor-compression refrigeration cycle has kept milk fresh, lettuce crispy, and leftovers tasty for nearly a century. Nevertheless, enterprising companies are revamping the refrigerator. Many are capitalizing on technology that allows consumers to take control of the temperature of the refrigerator. Sub-Zero's dual refrigeration system throws in an extra compressor for increased freshness and three evaporators (essentially expansion valves) to allow the user to control the temperature in different areas of the refrigerator (Sub-Zero). Maytag also provides its customers with two thermostats to fine-tune temperature (Maytag). Whirlpool's "In-Door Air Cooling System" directs air from the freezer into the refrigerator door to keep those items extra cold (Whirlpool). These Whirlpool refrigerators essentially have two refrigerants- air and ammonia.
Conclusion The refrigerator maintains a silent but powerful presence in today's home. His shiny skin and comforting hum masks his little secret: that he is an underappreciated marvel of engineering. New gadgets and processes may change him in the near future, but his contributions to food preservation and life itself will remain for all time.