<P> The 2nd - century Chinese mechanical engineer and inventor Ding Huan of the Han Dynasty invented a rotary fan for air conditioning, with seven wheels 3 m (10 ft) in diameter and manually powered by prisoners of the time . 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 . </P> <P> In the 17th century, the Dutch inventor Cornelis Drebbel demonstrated "Turning Summer into Winter" as an early form of modern air conditioning for James I of England by adding salt to water . </P> <P> Modern air conditioning emerged from advances in chemistry during the 19th century, and the first large - scale electrical air conditioning was invented and used in 1902 by American inventor Willis Carrier . The introduction of residential air conditioning in the 1920s helped enable the great migration to the Sun Belt in the United States . </P> <P> 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 speed up the evaporation . They lowered the temperature of the thermometer bulb down to − 14 ° C (7 ° F) while the ambient temperature was 18 ° C (64 ° F). Franklin noted that, soon after they passed the freezing point of water 0 ° C (32 ° F), a thin film of ice formed on the surface of the thermometer's bulb and that the ice mass was about 6 mm (⁄ in) thick when they stopped the experiment upon reaching − 14 ° C (7 ° F). Franklin concluded: "From this experiment one may see the possibility of freezing a man to death on a warm summer's day" </P>

Who is widely regarded as the inventer of air conditioner