Cooling tower is a device that use water as a circulating coolant to absorb heat from a system and discharge it into the air to reduce water temperature. The cooling effect is utilizing the steam that produced from the heat transfer when the water and air contact, and then steam volatilization the heat will be taken away to achieve evaporation heat, convective heat transfer and radiative heat transfer and other principles to disperse the industry or refrigeration air conditioning generated heat to reduce the water temperature, to ensure the normal operation of the equipment.

To distinguish between opened cooling-tower and closed cooling tower, by observing that whether water is in direct contact with air.