Cooling towers are proven to be an essential part of manufacturing and industrial plants. Cooling towers are categorized into two main kinds- the closed circuit cooling tower and the open circuit cooling towers. Under each kind are the different types and designs. Today, we are going to talk about the 5 main types of open circuit cooling towers.
Although cooling tower systems are mostly used by manufacturing plants and industrial buildings, many large office buildings are also now enjoying the benefits that an efficient system offers. Cooling towers are proven to be an essential part of manufacturing and industrial plants like petrochemical plants, chemical plants, oil refineries, thermal power stations or power generation plants, and other industries with buildings that need a fully functional HVAC system for cooling. The main purpose of industrial water cooling towers is to efficiently and effectively extract and reject waste heat from the industrial plants, manufacturing buildings, and large offices by cooling the water used in various processes and by generating lower water temperatures.
Cooling towers are categorized into two main kinds- the closed circuit cooling tower and the open circuit cooling towers. Under each kind are the different types and designs. Although all the types and kinds of cooling towers perform the same function, they differ in various points especially in terms of how they cool the water used in the process.
Today, we are going to talk about the 5 main types of open circuit cooling towers. But before that, let us discuss first what is an open circuit cooling tower and a closed circuit cooling tower, as well as the primary difference between the two.
Open Circuit Cooling Tower
The open circuit cooling tower is an enclosed heat exchanger or structure that distributes warm water over a fill or packing and cools down the warm water through direct contact with air. The labyrinth-like fill provides an expanded air-water interface for air heating which allows evaporation to occur. Partially, the heat transfer happens by way of heat exchange, and mainly via evaporation. It is during evaporation when the water has to be cooled down. The process of cooling down takes place as the water falls through the fill. The water will then be collected in the cold basin built below the fill. The heated air which is heavily loaded with moisture leaves the fill and gets released into the atmosphere.
An open circuit cooling tower system offers optimal cooling and allows low process temperatures. This system also provides colder water. Though the operating cost of an open cooling tower is generally lower, it may dramatically increase in time as this type of cooling system needs additional water treatment. The cost may even increase if the heat exchangers get fouled. In order to prevent or at least minimize the chances of fouling and other issues that affect the efficiency of the system, the cooling tower parts especially the heat exchangers have to be checked and maintained regularly.
Closed Circuit Cooling Tower
A closed circuit cooling tower functions almost the same way as the open circuit cooling tower. What makes the previous different from the latter is the fact that it does not involve direct contact between the fluid being cooled and the air. Also, the closed circuit cooling tower has a heat exchanger coil built within the tower. This coil is responsible for separating the cooling tower water from the cooling water.
The closed circuit cooling tower is also designed with two separate fluid circuits. Unlike an open circuit cooling tower, a closed circuit cooling tower does not experience fouling which is mainly caused by dirt and oxygen. This is because the cooling water is contained in the coil and is not exposed to the atmosphere.
Different types of open circuit cooling tower
There are 5 primary types of open circuit cooling towers. These are:
- Round / Bottle Cooling Tower
- Square / Rectangular Cooling Tower
- Field Erected Cooling Tower
- Fan Less, Fills Less Cooling Tower
- Cross Flow Cooling Tower
Round / Bottle Cooling Tower
The round cooling tower, also called the bottle shape cooling tower, is popularly known for its superb technology and outstanding compact design. It is available in different flute sizes. Because of its round shape, it allows the air flow to get evenly distributed and it also offers maximum heat transfer per contact surface area and unit volume. The round or bottle cooling tower uses the counter flow-induced draft technology and is designed with cross corrugated PVC film fills heat transfer media. It is constructed from fiberglass-reinforced plastics.
The round cooling towers are usually fabricated and designed at the water cooling towers manufacturers’ factory and are only assembled at the job site. This can be used in various applications including process cooling, chemical plants, HVAC, refrigeration, steel melting, light to medium industrial plants, plastic processing plants, and pharmaceutical plants.
Fan Less, Fills Less Cooling Tower
As its name suggests, the fanless, fill less cooling tower does not have any fill or fan which is used to cool down the waste heat water. Instead, it utilizes the outside wind passage as the cooling media. It has wooden louvers that serve as the sidewall that restricts water spillage.
The fanless, fill less cooling tower is the most economical choice and has the lowest maintenance cost among the different types of cooling towers.
Cross Flow Cooling Tower
The crossflow cooling water is best used for industrial applications. In this type of open circuit cooling tower, the air flows horizontally through the fills while the water vertically falls down. It is especially used in dirty water applications like an oil refinery and chemical process cooling where the water can get contaminated with ammonia compound, sugar, oil, fats, and other nutrients.
Square / Rectangular Cooling Tower
The rectangular or square cooling tower is perhaps the most popular cooling tower. Like the round cooling tower, the square cooling tower also utilizes the counter flow-induced draft technology. Its heat transfer media are cross corrugated PVC film fills.
The construction material of the rectangular or square cooling tower is fiberglass reinforce plastics while its structural components are made with mild steel, hot-dipped galvanized. Some models have pultruded fiberglass structure and gear reducer direct-drive electric motor.
The rectangular or square cooling tower is available in a single cell and multi-cell. It can be used in various applications including light to medium and medium to heavy industrial processes, pharmaceutical plant, refrigeration, process cooling, HVAC, steel melting/heating furnace, power generation, chemical plant, plastic processing plant, and chemical plant.
Field Erected Cooling Tower
Not all industrial and manufacturing plants can find the right standard designed cooling tower for their specific needs especially those with the poorest industrial ambiance. This is why there is this so-called field-erected cooling tower. This type of open circuit cooling tower is custom made. It is designed with pultruded fiberglass and is modeled using stainless steel for fasteners, pultruded FRP sections, fiberglass reinforced polyester (FRP) sheets for cladding, and other hardware.
The field-erected cooling tower can be used both for old and new cooling tower projects. As compared to the traditional constructional materials like wood, concrete, and steel, the FRP offers more advantages. One of its remarkable advantages is its resistance. FRP is highly resistant to various elements, fire, temperature, corrosion due to acid, salt, and sand, as well as to the varying weather conditions. The material is also highly recyclable and can remain friendly to the surroundings even for years. This type of cooling water is perfect for high-temperature cooling water process applications since it can withstand high-temperature levels. It can also be utilized for all kinds of water regardless of whether it is clean or not like seawater, chemical water, and brackish water, to name a few.
There are indeed many types of cooling towers. While all of these types serve the same purpose, not all of them can suit your needs well. It is important to know what your industrial plants’ needs are first before you pick a specific type of cooling tower. Remember that the efficiency and efficacy of the cooling tower depend on whether you picked the right type or not.