For improved fermentation the following is good to know
Power Number is a dimensionless parameter used for estimating the power consumed by the agitating turbine. The lower number the better ability to disperse gas into the media without flooding! All turbines shown on this page are from CerCell's selection manufactured from Nylon.
For a standard cylindrical vessel geometry, the power consumed by the turbine(s) at a specified rotational speed, for a liquid with known density, can be determined from the Power Number correlation.
P = Np ρ n3 D5
P = Turbine power, Watts
Np = Power Number
ρ = Density of liquid, kg/m3
n3 = Agitator speed measured in revolutions / second
D5 = Impeller diameters in meters
Power Number data for different type of rotors - turbines, under a give set of conditions are documented in various technical literature. Typical values of Power Number (Np) are:
- Radial flow turbines, such as Rushton, Jacobs, Smith, Hjorth, Bakker: 2.5 to 6.5
Power Number decreases with an increase in Reynolds number.