Cooling tower working principle and installation method

Cooling Tower Working Principle and Installation Method Cooling towers play a significant role and are essential equipment in many large factories, shopping malls, and thermal power plants. They cool water carrying waste heat by exchanging heat with air inside the tower, transferring the waste heat to the air and dissipating it into the atmosphere. This article provides an in-depth understanding of the principles and types of cooling towers. I. Basic Principles of Cooling Towers A cooling tower is a device that cools water by using air contact with water (directly or indirectly). It uses water as a circulating coolant, absorbing heat from a system and releasing it into the atmosphere, thereby lowering the internal temperature and creating reusable cooling water. Schematic diagram of cooling tower circulation working principle 1. Heat dissipation relationship in the cooling tower In wet cooling towers, the temperature of the hot water is high, and the temperature of the air flowing over the water surface is low. The water transfers heat to the air, which carries it away and dissipates it into the atmosphere. Water dissipates heat to air in three ways: ① Contact heat dissipation; ② Evaporation heat dissipation; ③ Radiation heat dissipation. Cooling towers mainly rely on the first two methods of heat dissipation, and the amount of radiation heat dissipation is very small and can be ignored. 2. Evaporation heat dissipation principle Evaporation heat dissipation is accomplished through mass transfer, i.e., through water molecules continuously diffusing into the air. Water molecules have different energies, and the average energy is determined by the water temperature. Near the water surface, some water molecules with high kinetic energy overcome the attraction of neighboring water molecules and escape the water surface to become water vapor. Because high-energy molecules escape, the energy of the water near the surface decreases. Therefore, the water temperature decreases. This is evaporative heat dissipation. It is generally believed that the water molecules that evaporate first form a thin layer of saturated air on the water surface, with the temperature being the same as the water surface temperature. Then, the rate at which water vapor diffuses from the saturated layer to the atmosphere depends on the difference between the water vapor pressure in the saturated layer and the water vapor pressure in the atmosphere, i.e., Dalton's law, which can be represented by the following diagram. Cooling tower water evaporation process working principle diagram II. Basic Structure of Cooling Towers Air conditioning cooling towers are mainly composed of the cooling tower body, motor, fan, packing, water distribution device, water pipes, etc. Packing cooling tower structure diagram Supports and tower body: External support Packing: Provides the largest possible heat transfer area for water and air Cooling basin: Located at the bottom of the cooling tower to receive cooling water Water collector: Recovers water droplets carried away by the air flow Air inlet: Cooling tower air intake Spray device: Sprays cooling water Fan: Sends air into the cooling tower Axial flow fan: Used for induced draft cooling towers Axial/centrifugal fan: Used for forced draft cooling towers Cooling tower louvers: Average incoming airflow; retain moisture inside the tower III. Types of Cooling Towers With the rapid development of industry, there are many different types of cooling towers, which are mainly divided into the following types: 1. By ventilation method: ① Natural draft cooling tower; ② Mechanical draft cooling tower; ③ Mixed draft cooling tower 2. By contact method of water and air: ① Wet cooling tower; ② Dry cooling tower; ③ Dry/wet cooling tower. 3. By flow direction of hot water and air: ① Counterflow cooling tower; ② Crossflow (direct exchange) cooling tower; ③ Mixed flow cooling tower 4. By application field: ① Industrial cooling tower; ② Air conditioning cooling tower. 5. By noise level: ① Ordinary cooling tower; ② Low noise cooling tower; ③ Ultra-low noise cooling tower; ④ Ultra-quiet cooling tower. 6. By shape: ① Round cooling tower; ② Square cooling tower. 7. By whether water and air are in direct contact: ① Open cooling tower; ② Closed cooling tower (also known as closed cooling tower, sealed cooling tower). There are other types of cooling towers, such as jet cooling towers and fanless cooling towers. The above is the basic knowledge of cooling towers. In the next section, we will focus on analyzing the design and selection of cooling towers. Interested friends can learn together.