Power Number measured

Improved cultivation with measured impeller power

Vastly improved Np data (obtained december 2022) points for Power Number's (Np) on "small" OD 50-60 mm impellers.

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

Rotor Watt consumption (W) measured with high precision by Cilix - https://cronus-pcs.com/products/themis-motor-drive

Conditions: 2 liter of tap water at 20 °C in 3,200 ml CellVessel SUB, Head-Plate-Drive (HPD), vessel with 3 baffels, with 3 down tubes (deep tubes or sensors).

Impeller photo	Impeller name	300 rpm	400 rpm
	Kidney OD 60 mm 3 blades 45 °angle	0.2 W 1.9 Np	0.4-0.5 W 2.0 Np
	Kidney OD 60 mm 3 blades 30 °angle	0.1 W 1.1 Np	0.2-0.3 W 1.1 Np
	Pitch OD 60 mm 3 blades 45 °angle	0.1-0.2 W 1.4 Np	0.3-0.4 W 1.4 Np
	Pitch OD 60 mm 3 blades 30 °angle 30 °angle	0.1 W 1.0 Np	0.2 W 0.9 Np

Conditions: water at 20 °C in 3,200 ml CellVessel SUB, Head-Plate-Drive (HPD), 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 1.8 Np	0.4-0.5 W 1.9 Np
	Kidney OD 60 mm 3 blades 30 °angle	0.1 W 1.0 Np	0.2 W 1.0 Np
	Pitch OD 60 mm 3 blades 45 °angle	0.1-0.2 W 1.3 Np	0.3 W 1.3 Np
	Pitch OD 60 mm 3 blades 30 °angle	0.1 W 0.9 Np	0.2 W 0.8 Np

Comments:

1. With baffles PN drops with increasing RPM

2. Mechanical friction of the MST used for MBD is several times higher than agitation losses

3. Measurement tolerance estimated to be <± 10 %

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

Conditions: 2 liter of water at 20 °C in 3,200 ml CellVessel SUB, Head-Plate-Drive (HPD), vessel with/without baffels, with 3 down tubes, impellers mounted on a vertical axle extending down from head plate with no bearing seals for lowest possible mechanical friction.

Impeller name	300 RPM no baffels	400 RPM no baffels	300 RPM with baffels	400 RPM with baffels
Kidney OD 60 mm 3 blades 30 °angle	0.1 W 0.9 Np	0.1-0.2 W 0.8 Np	0.1 W 1.3 Np	0.2 W 0.9 Np
Kidney OD 60 mm 3 blades 45 °angle	0.1-0.2 W 1.8 Np	0.3-0.4 W 1.7 Np	0.2 W 2.1 Np	0.4 W 1.8 Np
Kidney OD 50 mm 3 blades 30 °angle	0.1 W 1.5 Np	0.1 W 1.1 Np	0.1 W 1.6 Np	0.1 W 1.1 Np
Torpedo without impeller 72mm	0.1 W 0.15 Np	0.1 W 0.15 Np	0.1 W 0.2 Np	0.1 W 0.15 Np

Impeller photo

Impeller name

300 RPM no baffels

400 RPM no baffels

300 RPM with baffels

400 RPM with baffels

Kidney

OD 60 mm

3 blades

30 °angle

0.1 W

0.9 Np

0.1-0.2 W

0.8 Np

0.1 W

1.3 Np

0.2 W
0.9 Np

Kidney

OD 60 mm

3 blades

45 °angle

0.1-0.2 W

1.8 Np

0.3-0.4 W

1.7 Np

0.2 W

2.1 Np

0.4 W

1.8 Np

Kidney

OD 50 mm

3 blades

30 °angle

0.1 W

1.5 Np

0.1 W

1.1 Np

0.1 W

1.6 Np

0.1 W

1.1 Np

Torpedo without impeller

72mm

0.1 W

0.15 Np

0.1 W

0.15 Np

0.1 W

0.2 Np

0.1 W

0.15 Np

Comments:

1. Np decreases slightly with decreasing blade angle

2. Mechanical friction is reduced as to HPD head plate bearing house without seal / seal-friction

3. Measurement tolerance estimated to be <± 10 %