Counter Flow vs. Cross Flow Cooling Tower Differences

29 September 2020

Cooling towers are primarily utilised by industrial and other types of buildings for heating, ventilation, and air conditioning (HVAC) purposes. They are maximised to provide cost-effective and energy-efficient cooling that is needed by various systems and equipment.

These cooling towers allow the interaction between water and air. This interaction is intended to decrease the temperature of the hot water that is circulating throughout the said towers. Water that is already cold will be sent back into the industrial process, ensuring that the temperatures of oil refineries, petrochemical, thermal power stations, nuclear power stations, and HVAC systems are essentially cold.

To date, cooling towers can be grouped into either counter flow or cross flow. The most common difference between these two configurations is the way the water interacts with the heat transfer surface. Here are some more details about the differences between these configurations.

Counter Flow Cooling Tower

Counter flow cooling towers have an induced draught fan on the top portion of the towers, which are directly situated on the motor. The fan from these cooling towers induces the ambient air into the tower so that it can draft upward. This air movement allows the speed of the exhaust air to be faster than the entry of the air to the tower. It also results in a low drop in pressure and lower circulation.

These cooling towers distribute water through pressurised spray nozzles by splashing downwards. The air, on the other hand, opposes the direction of the water by drafting vertically upward through the help of fillings and exiting out the top of the tower. This counter flow movement of both water and air makes it suitable for applications that critically need cold water temperature.

Counter flow cooling towers are enclosed fully, allowing them to prevent sunlight exposure and minimise algae growth. They are also lighter in weight and smaller in size compared to cross flow cooling towers. Several filling options are likewise available that can be applied to different industrial processes. However, the initial and long-term costs of these towers are higher than their counterpart. For flow rate systems, the chance of water freezing in the system is high.

Cross Flow Cooling Tower

Cross flow cooling towers, on the other hand, distribute hot water perpendicularly to the flow of the air. The air on the towers flows through the fills horizontally while the water flows from the top and falls down vertically. Splash type fillings are utilised for these towers, making them suitable for applications where water has high suspended particles.

As mentioned, water flows from the top of cross flow cooling towers with the help of gravity. Through the same gravity element, the water can be distributed evenly in the fill. Moreover, the spray nozzles of these towers do not need any additional pressurisation, which helps save a lot of energy. A deep pan listed with holes and nozzles makes up the distribution or the hot water basins of these towers.

Cross flow cooling towers have full door access that allows anyone to reach certain components of the towers. This accessibility ensures that adjustments and replacements can be done easily. Additionally, even water distribution prevents freezing problems within the towers. They likewise consume less energy. These towers, however, are prone to dirt and other external components due to their open structure. The non-compatibility of film type fills can also be a problem for these towers.

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