Review of researches on fouling generation in water circulation tubes and fouling removal methods

 Water-based central air conditioning system is a typical air conditioning system which uses water circulation for cooling or heating, and is widely used in the building field. Many impurities may enter the circulating water in water circulation tubes because the cooling towers of the water-based central air conditioning system are open to the external environment, leading to the fouling generation in water circulation tubes after long-term operation. In this paper, the research statuses of the fouling generation in the water circulation tubes are reviewed, including the fouling types, the fouling generation mechanism and the fouling acceleration methods. The influence factors on the fouling generation in the water circulation tubes are summarized, covering the operation conditions, the structure parameters of heat exchange tubes and the fouling compositions of circulated water. In addition, the progresses of physical and chemical fouling removal methods for water circulation tubes are analysed, and the test methods that can quickly evaluate the fouling degree and the fouling removal effect are summarized, which provides theoretical basis and research directions for further improving the fouling removal ability of water circulation tubes in the water-based central air conditioning systems.