20世纪重大工程突破-空调与制冷-美国国家工程院-Donald E. Ross.docxVIP

Greatest Engineering Achievements of The 20th Century-10 Air Conditioning and RefrigerationWhich of the appliances in your home would be the hardest to live without? The most frequent answer to that question in a recent survey was the refrigerator. Over the course of the 20th century, this onetime luxury became an indispensable feature of the American home, a mainstay in more than 99.5 percent of the nations family kitchens by centurys end. Keeping cool has been a human preoccupation for millennia, but until the 20th century most efforts were ineffective. People tried everything from draping saturated mats in doorways to the installation of water-powered fans. Even Leonardo da Vinci designed and built a mechanical ventilating fan, the first of its kind. The modern system—involving the exchange of hot, moist air for cool, dry air by way of a circulating refrigerant—was first used in industrial settings. Indeed, a North Carolina textile engineer named Stuart Cramer, impressed with how the latest system of controlling the heat and humidity in his plant improved the cloth fibers, coined the term air conditioning in 1906. Since then comfort of cool is no longer considered a luxury but a fact of modern existence.Timeline1902 Comfort cooling system installed at the New York Stock ExchangeA 300-ton comfort cooling system designed by Alfred Wolff is installed at the New York Stock Exchange. Using free cooling provided by waste-steam-operated refrigeration systems, Wolff’s system functions successfully for 20 years.1902 First office building with an air-conditioning system installedThe Armour Building in Kansas City, Missouri, becomes the first office building to install an air-conditioning system. Each room is individually controlled with a thermostat that operates dampers in the ductwork, making it also the first office building to incorporate individual zone control of separate rooms.1904 A self-contained mechanical refrigerator is displayed at the St. Louis Worlds FairA s