ANS:A - induced draft

An induced draft cooling tower is a type of cooling tower where the flow of air is induced or drawn through the tower by fans located at the top or the discharge side of the tower. In this design, the fans create a negative pressure or suction effect at the air discharge, which draws air through the tower from the bottom or the intake side. Here's a breakdown of the key components and the operation of an induced draft cooling tower:

1. Fan(s): Induced draft cooling towers are equipped with one or more fans located at the top or the discharge side of the tower. These fans create a suction force that draws air through the tower. The fans are typically axial flow fans, which are efficient in moving large volumes of air with relatively low power consumption.
2. Fill Media: Inside the tower, there is a fill media typically made of plastic or wood. The fill media provides a large surface area for the incoming air to come into contact with the water being cooled. This maximizes the contact between the air and water, facilitating heat transfer through evaporation.
3. Water Distribution System: Water is distributed over the fill media using a system of nozzles or spray heads. The water flows downward over the fill media, while air is drawn upward through the tower counterflow to the water flow.
4. Heat Exchange: As the water flows over the fill media, it comes into contact with the upward-flowing air. Heat from the water is transferred to the air through evaporation, cooling the water. The cooled water collects at the bottom of the tower and is then recirculated back to the process that requires cooling.
5. Drift Eliminators: To minimize water loss due to entrainment by the airflow, induced draft cooling towers are typically equipped with drift eliminators. These devices help to capture water droplets entrained in the air before they can escape the tower, reducing water loss and preventing potential environmental concerns.

Overall, induced draft cooling towers offer efficient cooling by utilizing fans to draw air through the tower, maximizing the contact between air and water for effective heat transfer through evaporation. They are commonly used in various industrial processes, power plants, HVAC systems, and other applications where effective heat dissipation is required.