How Cooling Towers Work

The cooling tower basically belongs to the heat exchange equipment system, and the two media for heat exchange are: water and air. The whole process is the joint action of contact heat dissipation and evaporative heat dissipation to cool the water, which is the process of evaporative cooling. Contact heat dissipation (heat transfer) - because there is a temperature difference when water and air are in contact, Tw>Ta, the air takes away part of the heat of the water, causing the water temperature to drop. Evaporative heat dissipation (mass transfer)-The water vapor formed by the evaporation of the water surface continuously diffuses into the air, and at the same time, the latent heat of vaporization of the water is brought into the air, and the water evaporates and absorbs heat to reduce the temperature of the remaining water.



The structural classification of cooling towers: according to the ventilation method: natural ventilation and mechanical ventilation; according to the flow direction of water and air: counter-flow, cross-flow and mixed flow; according to the contact mode of water and air: wet, dry and wet and dry.

According to the application: cooling tower for air conditioner and industrial cooling tower; according to the noise level: common type (P), low noise type (D), ultra-low noise type (C); according to the packing water spraying device: film type and drip type.



Cooling towers are divided into: counter-flow, cross-flow, ejector and evaporative (closed) cooling towers.



According to the shape, it is divided into round and square.



Counter flow Cooling Tower: Circular Counter-flow Cooling Tower Square Counter-flow Cooling Tower

(1) There is a large height difference between the air inlet and the air outlet, so the air in and out is not easy to flow short, which can ensure that the temperature of the inhaled air is low.

(2) The heat exchange efficiency of the counter flow cooling tower is the highest.

(3) The air inlet louvers of the circular counter flow tower can be arranged along the circumference, and the square tower can also be arranged around, so the air inlet is more uniform and the cooling effect is good.

(4) In terms of external dimensions, the diameter of the circular tower is larger than that of the square tower with the same performance, and the side length is also larger. Due to these reasons, the use of the circular tower is affected to a certain extent due to the limitation of the occupied area.



2. Cross flow cooling tower: The heat exchange efficiency of cross-flow cooling tower is not as good as that of counter-flow tower. The height difference between the air inlet and the air outlet is also much smaller than that of the counterflow tower. If the air outlet is affected and hindered by some kind of airflow or other objects, the short flow phenomenon will occur between the air inlet and the outlet. In addition, half of the water inlet of the cross-flow tower is at the top of the tower body, so it is usually required to have a horizontal main pipe above the tower, and the pipe layout is slightly difficult.



3. Ejection cooling tower: The cooling fan is canceled, and high-speed water is injected through the water nozzle, thereby injecting a certain amount of air into the tower for heat exchange and cooling. There is no running equipment such as fans, high reliability, good stability, and lower noise than other types of cooling towers. The disadvantage is that the size of the equipment is too large and the cost is relatively expensive. At the same time, due to the requirements of the jet flow rate, it requires a higher water pressure into the tower.



4. Evaporative cooling tower (closed cooling tower): The cooling water system is a fully closed system, which has a good guarantee for water quality, is not easy to be polluted, and impurities will not enter the cooling water system. Another advantage is that it can be used outdoors When the temperature is low (transition season), it can be regarded as an evaporative cooling refrigeration equipment, so that the cooling water can be directly used as the cooling water of the air conditioning system. Thereby reducing the running time of the unit. However, its power consumption is large, and the water pressure requirement for entering the tower is relatively high. The main components of the cooling tower: transmission system: motor, reducer, fan. Water distribution system: such as rotating water distributor; fixed water head; water distribution tank, water distribution plate; tower body and support, air duct, water collector, packing, rain area, water collection tank, wind deflector and other parts. Normal, medium and high temperature division range of cooling tower: normal temperature tower: ≤40°C; medium temperature tower: 40°C<°C≤45°C; high temperature tower: 45°C<°C≤65°C. How the cooling tower works: Hot water generated by the process or air conditioning system is distributed over the fill. Fans move ambient air through water droplets (spot fill) or a film of water (film fill) on the fill. The heat in the water is transferred to the air through sensible and latent heat exchange.