Cooling Tower Fan Power Adjustment Curve
For CoolingTower:VariableSpeed or CoolingTower:VariableSpeed:Merkel, what Fan Power Ratio Function of Air Flow Rate Ratio Curve does everyone use? Cooling tower suppliers rarely provide technical data about it.
I listed some candidates in the table and the chart below.
The most likely candidate is (C) PNNL ASHRAE 90.1 Reference Manual. Originally, the curve is expressed as a function of PLR, but I interpret it as a function of air flow rate ratio. One thing to note is that the minimum air flow rate ratio must be 0.4 or greater. The curve increases the fan power when the air flow rate ratio is below 0.4.
(D) and (E) are from EnergyPlus ExampleFiles. Both are similar to (B) the theoretical curve proportional to the cube of the air flow rate ratio.
Which curve are you using? Or any other sources?
