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我的文档（My document） Air conditioning refrigeration system In this paper, This paper introduces the development history of air conditioning system with aircraft manufacturing technology, and introduces the development direction of future air conditioning system by introducing the refrigeration principle of air conditioning system in various stages. keywords Refrigeration; Air conditioning; Air circulation; The evaporation cycle suddenly collapsed. From 1903, the Wright brothers made the first successful human history of the aircraft off the ground a few metres high, to todays civil aviation fixed-wing aircraft operating in the 10000 meters around the bottom of the troposphere to the stratosphere, and even some of the military aircraft flying at an altitude of twenty thousand meters. In order to enable the driver to survive and improve the comfort of driving, the application of air conditioning system on the aircraft with the increase of flight speed and flight height is also constantly being innovated. The function of air conditioning system: produce pressure, provide suitable temperature, provide oxygen. 1 the introduction In August 1909, French pilot louie blerio made the leap to the English channel, where the planes altitude was low and the planes load was inefficient. So in the early days of aviation pilots wearing a thick warm clothing can only in flight, until the loading on the airplane air conditioning system started in 1936, the pilots to fly from extreme environment. 2. Causes of air conditioning system Since air has weight, so can produce stress, the effect of gravity makes the air distribution is very uneven, the density of air is, the greater the more close to the surface of the earth so atmospheric pressure is, the greater the with the increase of altitude, atmospheric pressure drops. The low pressure is also harmful to the human body, as the atmospheric pressure decreases, the person experience the high altitude of the upper air pressure, the histosis an