1.-Usually the size of the cooling tower can be determined by several values:

• Water flow to be cooled.
• Inlet water temperature.
• Outlet water temperature.
• Wet bulb temperature or placement of the cooling tower.
• Heat to be rejected in the cooling tower
  

2.- The efficiency of a cooling tower depends mainly on the heat exchange surface that has been assembled, on the good distribution of the water, on the amount of intake air and on the external air conditions. The theoretical limit of cooling is the temperature in the wet bulb. This temperature can be determined on the Molier i-x diagram if the air temperature and relative humidity are known. The difference between the required cold water temperature and the wet bulb temperature (called cooling limit distance), is significant to determine the size of the tower.

The bigger the distance is, the smaller the tower becomes and therefore the more economical. The limit distance must be of at least 3-4ºC.