The closed cooling tower is a kind of evaporative cooler, which uses the spray water outside the coil to absorb the heat of the cooled fluid inside the coil after partial evaporation. The closed cooling tower uses two stages of cooling: the first stage is air cooling, and the cooler coil is cooled by air; The secondary cooling uses air cooling and spray. When the ambient temperature is relatively high, the secondary cooling is used. The spray system sprays water onto the surface of the cooler while the air cooling, which can take away the heat of the coil when the water evaporates, thus achieving the cooling effect.

High-temperature process fluid first enters the dry-cooled fin tube bundle for cooling, then enters the evaporative wet-cooling coil section in series, and flows out after further cooling. The spray water is sent from the collecting tank to the spray water distribution system above the wet cooling evaporation coil by the spray pump. Evaporation heat exchange is carried out on the surface of the evaporation coil wetted by the spray water, and the spray water falls to the collecting tank after passing through the coil. The air flowing through the coil is saturated with steam and takes away heat, while the fan cools the fluid in the fin tube.

In dry/wet combined operation mode, sensible heat and latent heat of evaporation are utilized. Compared with traditional evaporation equipment, the trend of white fog generation can be greatly reduced, and a large amount of water can be saved. After the temperature reaches the design temperature, the spray water can be stopped and cooled by air. The high temperature medium enters the dry cooling coil, transfers heat to the fins through the base tube, and convective heat exchange with the high speed passing airflow, takes away heat energy and reduces the temperature.