How Closed Cooling Towers Work

The working principle of closed-loop cooling towers is primarily based on the evaporative cooling technology, with its design originating from evaporative coolers used in industry. High-temperature water from condensers, absorbers, or process equipment is pumped or pressurized by other pressure devices and delivered to the cooling coils of the tower. The circulating water enters the cooling tower. Heat is exchanged through the movement within the tower and contact with air currents. The return water after entering the tower flows through pressure swirl nozzles installed at the top of the tower and above the air ducts, forming high-speed vertical and downward-moving spray droplets, which increase the surface area of the water droplets. During the spray process, the droplets also encounter rising air currents, which slows down the descent rate of the water particles and extends the heat exchange time. The heat from the fluid first transfers to the inner wall of the copper tubes, then to the outer wall, and finally to the spray water film. The water film and air form a saturated moist steam. The fan releases the heat into the atmosphere, and some of the water droplets are recovered by the collector to reduce the loss of spray water. When the spray water is reduced to a certain amount, the float valve automatically replenishes water to continue the cycle. Additionally, as the cooling tower removes the packing material, it becomes an empty tower, reducing the internal resistance. Under the action of the fan, the wind speed and volume are increased, enhancing the air-water ratio, thereby improving the cooling efficiency.