Basic concept of Cooling tower

Basic concept of Cooling tower.

Cooling Tower Types

Cooling towers fall into two main categories: Natural draft and Mechanical draft.

Natural draft towers use very large concrete chimneys to introduce air through the media. Due to the large size of these towers, they are generally used for water flow rates above 45,000 m3/hr. These types of towers are used only by utility power stations.

Mechanical draft towers utilize large fans to force or suck air through circulated water. The water falls downward over fill surfaces, which help increase the contact time between the water and the air this helps maximize heat transfer between the two. Cooling rates of Mechanical draft towers depend upon their fan diameter and speed of operation
.

Mechanical draft towers are available in the following airflow arrangements:

1. Counter flows induced draft.

2. Counter flow forced draft.

3. Cross flow induced draft.

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Basic concept of Cooling tower

Factors affecting on cooling tower performance

Factors affecting on cooling tower performance

THE factors affecting Cooling Tower performance are:

1.            Dry bulb and wet bulb temperature of the air

2.            Capacity C

3.            Range

4.            Approach

5.            Efficiency of contact between air and water

6.            Heat load

Ambient wet bulb temperature is a condition measured by a device called a psychrometer. A psychrometer places a thin film of water on the bulb of a thermometer that is twirled in the air. After about a minute, the thermometer will show a reduced temperature. The low point when no additional twirling reduces the temperature is called the wet bulb temperature.

Cooling tower performance is related to ambient wet bulb conditions. Higher wet bulb temperatures occur in the summer when higher ambient and relative humidity occurs.

The measured wet bulb temperature is a function of relative humidity and ambient air temperature. Wet bulb temperature essentially measures how much water vapor the atmosphere can hold at current weather conditions. A lower wet bulb temperature means the air is drier and can hold more water vapor than it can at a higher wet bulb temperature.

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 Basic concept of cooling tower and factors affecting in cooling Tower performance.