Power Number measured

Improved cultivation with measured rotor power

Here presented the first set of data point for Power Numbers on small OD 50-60 mm impellers. As to the low Watt consumption for agitation some tolerances is unavoidable.

Impellers to be found on - https://cercell.com/support/cellvessel-details/impeller-available/

Data measured using the Perseus from Cronus-PCS - https://cronus-pcs.com/products/themis-family/perseus/

Magnetic-Bottom-Drive (MBD) driven impellers used.

Conditions: 2 liter of water at 20 °C in 3200 ml SUB, Magnetic-Bottom-Drive, vessel with 3 baffels, with 3 down tubes.

Impeller photo

Impeller name

300 rpm

400 rpm

Kidney
OD 60 mm
3 blades
45 °angle
0.4 W
 
4.2 Np
0.5-0.6 W
 
2.4-2.9 Np
Kidney
OD 60 mm
3 blades
30 °angle
0.4 W
 
4.6 Np
0,5-0,7 W
 
2.5-3.0 Np
Pitch
OD 60 mm
3 blades
45 °angle
0.5 W
 
5.4 Np
0.8 W
 
3.6 Np
Pitch
OD 60 mm
3 blades
30 °angle

30 °angle

0.5 W
 
5.2 Np
0.8 W
 
3.6 Np


Conditions: water at 20 °C in 3200 ml SUB, Magnetic-Bottom-Drive (MBD), vessel without baffles, with 3 down tubes.

Impeller photo

Impeller name

300 rpm

400 rpm

Kidney
OD 60 mm
3 blades
45 °angle
0.2 W
 
2.1 Np
0.3 W
 
1.4 Np

Kidney
OD 60 mm
3 blades
30 °angle

0.3 W
 
3.3 Np
0.3 W
1.4 Np

Pitch
OD 60 mm
3 blades
45 °angle

0.3 W
 
3.0 Np
0.3 W
 
1.6 Np

Pitch
OD 60 mm
3 blades
30 °angle

0.4 W
 
4.5 Np
0.5 W
 
2.5 Np
Comments:
1. With baffles PN drops with increasing RPM
2. Mechanical friction of MBD is several times higher than agitation losses
3. Measurement tolerance estimated to be ± 20 % and increasing with reduced RPM


Head-Plate-Drive (HPD) parts used for testing.

Conditions: 2 liter of water at 20 °C in 3200 ml SUB, Head-Plate-Drive (HPD), vessel without baffels, with 3 down tubes, impellers mounted on a vertical axle extending down from head plate with no seals for lowest possible mechanical friciton.

Impeller photo

Impeller name

300 rpm

400 rpm

500 rpm

Kidney
OD 60 mm
3 blades
30 °angle

0.2 W

1.4 Np

0.3 W

1.3 Np

 

 

Kidney
OD 60 mm
3 blades
45 °angle

0.2 W

1.3 Np

0.1 W

0.9 Np

 

 

Kidney
OD 50 mm
3 blades
30 °angle

 

0.2 W

2.0 Np

0.3 W

1.4 Np

 

Torpedo without impeller
72mm

0.2 W

0.8 PN

0.3 W

0.5 Np

 

Comments:
1. PN increases slightly with decreasing blade angle
2. Mechanical friction is reduced vastly to HPD head plate bearing friction
3. Measurement tolerance estimated to be ± 20 % and increasing with reduced RPM