Cooling tower is a device used to dissipate the heat and create a cooling action in factories, refineries, water chillers of the air conditioning systems of large buildings and various industries.
In fact, a cooling tower is a type of heat exchanger which dissipates water heat and lowers its temperature by bringing air and water into direct contact.
In the air conditioning process, 3 factors of temperature, humidity and air flow must be controlled. Accordingly, all air conditioners use a fluid to transfer heat, which can be "all air", "all water" or "air-water", depending on the type of equipment.
Dama Tajhiz has been operating in the field of air conditioning systems and cooling and heating equipment for many years, and the cooling tower is one of its products. Thanks to its technical knowledge and high experience, its cooling towers are produced with very high quality and exported to West Asian countries. The application, advantages and various types of this device are explained below.
In most factories and industrial processes, heat dissipation is an important issue for continuing operation. To this aim, water is usually used to remove the excess heat from the system. In the past, natural water such as river water was used for this purpose. In this way, the river water passed through the system, absorbed the excess heat and then returned to the river bed or was discharged into the sewage.
The cost of water supply increased dramatically over time, and given ecological problems, the environmental protection laws became much stricter. Given these conditions, the use of natural water resources was not feasible and even economical anymore; therefore, cooling systems such as cooling towers were designed to dissipate excess heat from industrial units and residential buildings.
The figure below shows the inlet, outlet and main part of a cooling tower.
The feed water, which may come from a well, municipal water or any other source, enters a cooling tower through the inlet pipe, as shown in the middle of the image on the left, and after the refrigeration process, water with the desired temperature flows out of the outlet line, as shown at the bottom right side of the image.
But what happens in a cooling tower and how does it reduce the inlet water temperature?
Inlet water temperature reduction is based on thermal exchange between water and air. We know that water needs a lot of heat to evaporate, and the cooling tower operates on this basis.
A very small amount of water evaporates due to more heat reception, and this heat and water vapor is discharged from the cooling tower by a fan. As a result, the water that remains in the tank of the device will have a lower temperature because of its losing the excess heat.
How does this happen operationally?
The tank water is pumped to the nozzles located at the top of the cooling tower. The pumped water is then spilt by the nozzles in droplet sizes into the packings between the nozzle and the cooling tower tank.
Meanwhile, the air inside the cooling tower, which has more heat, moves upwards and collides with the water droplets on the packings, causing a small portion of the droplets to evaporate. With this superficial evaporation that occurs in water droplets, what remains from these droplets loses most of its heat, cools down and returns to the device tank with a lower temperature.
Now that we have understood the general water cooling process in a cooling tower, the following two more questions spring to mind:
- What is a cooling tower packing and what is its function?
- How does hot air flow from the bottom upwards to discharge excess heat and water vapor?
To answer the first question, we must say that according to the laws of physics, the higher the air-water contact level, the more superficial evaporation and consequently the more heat transfer. Therefore, cooling towers should be designed in such a way that they enable a higher level of water-to-air contact. A packing is used for this purpose.
In the past, wood, straw and clay were used in cooling towers for this purpose, but the packings' material changed over time thanks to technological advances.
Nowadays, Dama Tajhiz utilizes honeycomb or PVC packings to increase the efficiency and cooling capacity of cooling towers.
Another important factor in increasing the efficiency of packings is their dimensions, which have a direct effect on the amount of joint surface and the duration of water-to-air contact. Because of the limited space inside the packings, the optimal size for cooling surfaces should be considered in the construction of cooling towers.
Now let's deal with the second question: How is airflow created?
We need air flow for more air-water contact as well as heat transfer from the tank water to the outside air.
For this reason, the sides of the cooling tower body have open louvers for fresh air flows. Air flows inside from the body of the device and when water droplets fall down through the nozzle and packing, this fresh air flows upwards and pushes the heat of the water droplets out of the system.
The upward flow of air in the cooling tower occurs in two ways. First, the air near the cooling tower, which is lower in height, is warmer and therefore lighter. Therefore, the hot air flows upwards naturally.
However, we still need to increase the speed of airflow in order to improve the efficiency of the device. For this purpose, an air conditioning fan is placed on top of the cooling tower, which mechanically pushes the incoming air from the device vents upwards from inside the cooling tower, thus creating an acceptable air flow.
Repairs and maintenance
A cooling tower, like all other mechanical systems and equipment pieces, undergoes physical depreciation during operation, which can affect its performance over time.
The evaporation of water in a cooling tower increases the concentration of water-soluble substances, creating sediment in its pores and pieces, such as packings, nozzle system branches and sprays. This can cause a significant reduction in its efficiency or serious damage to its equipment pieces. The result will be an increase in its operating costs caused by higher water and energy consumption, as well as an increase in its repair costs.
Therefore, this device must be serviced periodically for its better maintenance and in order to prevent any damage to it, reduce its possible repair costs and maintain its efficiency.
Two important points need to be considered in the periodic maintenance of this device:
First, how often should a cooling tower be serviced? To answer this question, we must consider that various factors such as the size of the device, its construction date, softening of the inlet water and quality of its equipment affect the optimal period of service. However, in general, the best time interval to service it ranges between 6 and 12 months.
The second important and effective parameter in determining the service period of the device is the use of special methods and equipment to increase the duration of this period. For example, the use of an intelligent remote control system to control the speed of the fan, high-quality raw materials in the construction of the device, air filters; separation of dry air pollution; regular lubrication of its equipment pieces such as bearings and especially the use of water softening systems can be effective in determining the appropriate time periods for servicing it.
Price of Dama Tajhiz cooling towers
When purchasing the device, you should pay more attention to its quality, thickness of its fiberglass body and its required capacity than its price. After choosing the right size for your desired application, you should know that the quality and price of the device are affected by various parameters, including:
- Material: fiberglass, metal or concrete
- Body thickness and quality of raw materials used in the body
- Shape (being round or cubic)
- Whether the cooling system circuit is open or closed
In addition to producing cooling towers with the best and most quality materials, Dama Tajhiz has provided the possibility of its purchase for Iran's neighboring countries such as Iraq, UAE, Turkey, Qatar and other West Asian countries at reasonable prices.
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