Science and technology of the Tang dynasty
The inventor Ding Huan (fl. 180 AD) of the Han dynasty invented a rotary fan for air conditioning, with seven wheels 3 m (10 ft) in diameter and manually powered. In 747, Emperor Xuanzong had a "Cool Hall" built in the imperial palace, which the "Tang Yulin" (唐語林) 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, written sources mentioned the air conditioning rotary fan as even more widely used.
Christian Steenstrup
Christian Steenstrup (December 2, 1873 – November 28, 1955) was a Danish inventor who invented the hermetically sealed refrigeration unit while Chief Engineer at General Electric, and held over 100 patents.
His improvement to the refrigerator sent the sales of the G.E. Monitor Top refrigerator soaring.
Streenstrup immigrated to the US in 1894.