Hi everybody! I'm currently working on a project where a wet cooling tower is involved. The wet cooling tower is an induced draft system. I know the volume of air handled and also the properties of the air entering and leaving the system. I want to determine the electricity consumption of the fan depending on these parameters. I have found two formulas. The first comes from the .pdf "SPX - Cooling tower fundamentals", at the page 58, they present several formulas and there is one to calculate the power output of a fan: spxcooling.com/pdf/Cooling-Tower-Fundamentals.pdf aph = ( Q * ht * D ) / (33000 * 12) where: aph -> air horsepower Q -> volume of air handled ht -> total pressure differential D -> density of water at gauge fluid temperature But this formula does not determine the electricity consumption of a fan. But the power output of one. Do you know if I can use an efficiency coefficient to calculate the electricity consumption? Then, I found this website (http://www-old.me.gatech.edu/energy/beth/four.htm#A2), it gives an equation for the fan horsepower: hp = A * cfm^B where: cfm -> air flow rate in the tower A and B -> constants which correspond to a particular tower box size What do you think about this equation? It may work, but I have looked for these two coefficients and I still haven't found them. Thank you for your help.