Differences between closed-type cooling towers and open-type cooling towers

Thread Content

1. The cooling principle of an open-type cooling tower is to spray circulating water in the form of mist onto fiberglass fillers; through the contact between water and air, heat exchange takes place. Additionally, fans are used to circulate the air inside the tower, carrying away the heated air that has exchanged heat with the water, thereby achieving cooling. With this cooling method, the initial investment is relatively low, but the operating costs are high (water and electricity consumption). 2. The cooling principle of a closed-type cooling tower is, in simple terms, based on two cycles: an internal cycle and an external cycle. Without fillers, the main core consists of a copper tube surface cooler. ①Internal circulation: It connects with the target equipment to form a closed-loop system (the circulating medium is soft water). Cool the target device by removing heat from it to the cooling unit. ②External circulation: In a cooling tower, it is used to cool the cooling tower itself. It does not come into contact with the internal circulating water; heat is dissipated only through the copper tube surface coolers located in the cooling tower. Under this cooling method, the operation of the motor is controlled automatically based on the water temperature setting. Two cycles are required; when the environmental temperature is high in spring and summer, both cycles need to operate simultaneously. In autumn and winter, the ambient temperature is not high, and in most cases only an internal circulation is required. A closed-type cooling tower, also known as a sealed cooling tower or a closed cooling tower, is simply referred to as a closed tower. The closed-cycle cooling tower originated from the evaporation cooler; it is actually a heat exchanger that combines the properties of a water-cooled cooler and a conventional cooling tower. It represents a type of heat exchanger that lies between water coolers and air coolers, which is why some manufacturers refer to it as an “evaporation air cooler”. There are now many types of such cooling equipment, all of which share the common feature of spraying water outside the shell-and-tube heat exchanger and employing forced ventilation. Heat is transferred from the fluid being cooled inside the shell-and-tube heat exchanger to the water sprayed outside via the wall surfaces, and then to the air through forced convection between the sprayed water and the air. The heat transfer from the sprayed water to the air is primarily due to the latent heat of vaporization of the water and the sensible heat exchange between the water and the air. Since the cooled fluid flows in a closed cycle between the partitioned heat exchanger and the external process equipment, it is referred to as a \"closed tower\" to distinguish it from ordinary cooling towers where the cooled fluid comes into direct contact with air; accordingly, ordinary cooling towers are called \"open towers\".