Principle: The internal closed-circuit circulation is adopted, and the heat exchange is also performed with the outside world through the heat exchanger. The circulating water does not come into contact with the outside air, and the quality of the circulating water is guaranteed to the maximum extent.

Application: It is suitable for occasions where the cooled water cannot directly contact with the outside air and the inlet temperature is lower than about 80°C, there is sufficient water source for spraying and the water quality of the water source is not easy to scale.