Refrigerated Compressed Air Dryer and Desiccant Compressed Air Dryer are two types of compressed air dryer in common use. Refrigerated Compressed Air Dryer has advantage of non air wasted and low energy consumed, but it's localized on Dew Point. Though Desiccant Compressed Air Dryer has advantage of low Dew Point, it has disadvantage of purge air waste and high energy consume. Holysun company developed Low Dew Point Combined Compressed Air Dryer, it integrated advantages of Refrigerated Compressed Air Dryer and Desiccant Compressed Air Dryer, optimizing connection of pipeline and content, has reach the perfect point of economical and high quality low dew point air.