Energy losses and efficiency of centrifugal pump

Key Parameter for determining efficiency

• Flow
• Head
• Power

Determination of total head

Head
Measure of kinetic energy created by pump.

Suction head
 Measured from pump inlet pressure gauge reading.

Discharge head
 This is taken from the pump discharge side Pr. Gauge.

Different Types of Pump Head

• Total Static Head - Total head when the pump is not running 
• Total Dynamic Head (Total System Head) - Total head when the pump is running 
• Static Suction Head - Head on the suction side, with pump off, if the head is higher than the pump impeller. 
• Static Suction Lift - Head on the suction side, with pump off, if the head is lower than the pump impeller. 
• Static Discharge Head - Head on discharge side of pump with the pump off 
• Dynamic Suction Head/Lift - Head on suction side of pump with pump on 
• Dynamic Discharge Head - Head on discharge side of pump with pump on

Energy Loss in Pump

• Frictional losses 
• Recirculation losses 
• Incidence losses

Frictional losses

• Main energy loss is due to effect of friction in the flow

Recirculation losses

•When flow is below the designed flow rate
•When pump operates at its designed flow rate recirculation loss is almost zero

Incidence Loss

• Difference in blade angle and flow angle 
• It tends to have higher losses as we move away from designed flow rate point

Efficiency of a pump

•It is the ratio of output to input
•No machine are 100% efficient Can be classified as:

COMPARISON CHART

Factors to be considered from user side

• Size pump correctly.
• Operate close to the best efficiency point.
• Size all piping and valves correctly.
• Avoid all leakages

Reference:

1-Larry Bachus and Angel Custodio, (2003). Know and Understand Centrifugal Pumps.

2-Val S. Lobanoff Robert R. Ross, (1992). Centrifugal Pumps - Design and Application (2nd ed.)

3-Igor J. Karassik ,oseph P. Messina,Paul Cooper and Charles C. Heald,2001. Pump Handbook(3rd ed)