[attachment=7188]

A/C or AIR CONDETION SYSTEM OF AN AUTOMOBILE


By

ABUZAR SIDDIQUIE (07E21A0301) SANTOSH KUMAR SWAIN (07E21A0341)
VIDYA VIKAS INSTITUTE OF TECHNOLOGY

[AFFILIATED TO JAWAHARLAL NEHRU TECHNOLOGICA UNIVERSITY]
[SURVEY NO: 103&104, CHEVELLA, RANGA REDDY DIST.—501 503]

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History


The 2nd century Chinese inventor Ding Huan (fl. 180) of the Han Dynasty invented a rotary fan for air conditioning, with seven wheels 3 m (9.8 ft) in diameter and manually powered. In 747, Emperor Xuanzong (r. 712–762) of the Tang Dynasty (618–907) had the Cool Hall (Liang Tian) built in the imperial palace, which the Tang Yulin describes as having water-powered fan wheels for air conditioning as well as rising jet streams of water from fountains. During the subsequent Song Dynasty (960–1279), written sources mentioned the air conditioning rotary fan as even more widely used.
Medieval Persia had buildings that used cisterns and wind towers to cool buildings during the hot season: cisterns (large open pools in central courtyards, not underground tanks) collected rain water; wind towers had windows that could catch wind and internal vanes to direct the airflow down into the building, usually over the cistern and out through a downwind cooling tower. Cistern water evaporated, cooling the air in the building. Wind catchers were widely used throughout the medieval Muslim world, where they were used for air conditioning in many cities.
Ventilators were invented in medieval Egypt and were widely used in many houses throughout Cairo during the Middle Ages. These ventilators were later described in detail by Abd al-Latif al-Baghdadi in 1200, who reported that almost every house in Cairo had a ventilator, and that they cost anywhere from 1 to 500 dinars depending on their sizes and shapes. Most ventilators in the city were oriented towards the Qibla, as was the city in general.
In the 1600s Cornelius Drebbel demonstrated "turning Summer into Winter" for James I of England by adding salt to water.
In 1758, Benjamin Franklin and John Hadley, a chemistry professor at Cambridge University, conducted an experiment to explore the principle of evaporation as a means to rapidly cool an object. Franklin and Hadley confirmed that evaporation of highly volatile liquids such as alcohol and ether could be used to drive down the temperature of an object past the freezing point of water. They conducted their experiment with the bulb of a mercury thermometer as their object and with a bellows used to "quicken" the evaporation; they lowered the temperature of the thermometer bulb down to 7°F while the ambient temperature was 65°F. Franklin noted that soon after they passed the freezing point of water (32°F) a thin film of ice formed on the surface of the thermometer's bulb and that the ice mass was about a quarter inch thick when they stopped the experiment upon reaching 7°F. Franklin concluded, "From this experiment, one may see the possibility of freezing a man to death on a warm summer's day".