Cooling Tower – Types of cooling tower – Working Principle

Types of cooling tower:- Utilities are neither a reactant or nor a catalyst still its absence can impact the chemical reaction. Utilities are equivalent to the heart of any industrial process as they play an important role in maintaining adequate requirement of a product process.

There are different types of utilities used in chemical industry, among those we are talking about the basic utility and i.e. cooling water. Wide use of cooling water can be see in manufacturing industries such as in reactor’s jacket, in heat exchangers, in jacket of furnace and many more.

Cooling water is a utility that is used as both cold side and hot side fluid in heat exchangers depending on the temperature requirement. The general flow of the cooling water in an industry is described below steps.

1. Cooling water is pumped from the reservoir to the plant where it is used in the reactor’s jacket, in heat exchangers, in the jacket of the furnace.
2. After exchanging heat from those equipments, its temperature got increased hence it is sent to cooling tower.
3. Cooling towers reduce the temperature of the water.
4. The water again pumped to the plant and use as a utility for plant.

This is the basic flow of cooling water, where cooling water taken from the reservoir and pumped to the plant and after that the temperature is reduced by cooling tower and again it pumped to the plant. Hence to use the water again, cooling tower is used. In this article, we will learn types of cooling tower , working principle of cooling tower and how cooling tower works .

What is a cooling Tower?

Industrial cooling tower is a device which act as a heat rejection equipment. It rejects waste heat from the water and thereby reduces the temperature of water. It is used in industries to reduce temperature of water and thereby provide cooling water utility for the process.

Working principle of cooling tower – How does a cooling tower work?

Cooling tower works on the principle of evaporation. Hot water is sprayed from the top of cooling tower which exchange heat with the atmospheric air and results in reduction of temperature of hot water.

Convection mode of heat transfer is used in the cooling tower are heat transfer takes place between air and water.

Types of cooling tower

There are different types of industrial cooling tower. Classification of industrial cooling tower is described below

Natural Draft cooling Tower

Natural draft cooling tower works on natural convention to circulate the air completely through the tower. Hot water that comes from the plant and is to be cooled pumped using pump to the top of the cooling tower which is considered as inlet of cooling tower or hot water inlet.

The hot water inlet is connected to a series of nozzles also know as distributor with the help of which it get spray over the fill material evenly. The purpose of filling mater is to provides a more contact surface area for heat transfer. Fresh air is induced at bottom of the tower and which then flows in the upward direction where heat transfer takes place between warm water coming from top and and cool air coming from lower side. The hot water reject heat after contact with air and in that process fraction of water gets evaporated.

Water getting cooled after heat transfer collected at basin or the bottom of the tower and hot/Warm and moist air get discharged from the top of the tower to the atmosphere. Air movement takes place because of difference in density between the air that enters inside and the one that is already inside within the tower. The warm and moist air is denser as compared to the cool air and therefore, it rises through the tower. The dry and cool air from outside the tower will fall in, creating a constant cycle of air flow.

Mechanical draft

Working principle of mechanical cooling tower is pretty much same as natural cooling tower which is principle of evaporation but the only difference is here the air is circulated into the cooling tower is through mechanical means. here fans/ propellers are use to create air.

Mechanical draft cooling tower are again of two types:
1. Forced draft cooling tower
2. Induced draft cooling tower

Forced draft cooling tower

In the Forced draft system, an exhaust fan placed at the base which forced the air to flow from the bottom to top of the tower. A drift eliminator is installed inside the tower to prevent the loss of water droplets along with the forced air.

Induced draft cooling tower

In an induced draft cooling tower. fan is installed centrally at the top, which creates suction in the cooling tower and discharges it to the atmosphere. This creates a flow of air from bottom to top with a force and results in a reduction in the temperature of hot water. The only between the induced draft cooling tower and forced draft cooling tower is that the fan is located at the top in the induced draft cooling tower.

This was the classification of mechanical draft industrial cooling tower based on the placement of fans.

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Another types of cooling tower are categorized is based on air flow pattern. There are two type

1. Cross flow cooling towers
2. Counter flow cooling tower

1. Cross flow Cooling Tower

In a crossflow cooling tower, hot water sprayed from the top which is perpendicular to air which enters from the sidewalls of the tower horizontally and then rises upward from the center of the cooling tower. In crossflow cooling towers air enters at 90 degrees in the direction of the water. As the flow of water and air cross each other, these types of cooling towers are called crossflow cooling towers.

2. Counter flow Cooling Tower

In counterflow cooling towers, The water is sprayed through the pressure nozzles near the top of the tower and flows down through the fill material and air entered beneath fills and moves upward opposite to the direction of the water flow. As the air flow and water flows in the cooling tower are in counter to each other, these cooling tower are called as counter flow cooling towers.

Wrapping Up

Hope you like this tutorial on cooling where we had tried to cover all the aspect about cooling tower along with cooling tower calculation. In meantime, you can detailed post on Vapour absorption Chiller (VAM) which is used in the chemical industry to create chilling water. read If you find this information useful then do appreciate us in the comment section and in case you find some information missing then let us know, we will incorporate it in our article.