GPS-X Technical Reference

333 Tools Object
The variable speed model is built with an energy optimization algorithm in which the
model finds a pump speed at which consumption of pumping energy is minimized. The
typical outputs for the variable speed pumps are:
1) number of pumps required to be operated
2) speed of the pumps
3) efficiency of the pump
4) system head, pump head
Typical Model Outputs
The typical outputs from the variable speed pump model are as shown in Figure 11-27.
Following observations may be made by comparing the outputs of variable speed pump
and fixed speed pump.
1) The pump head follows the required system head more closely [Figure 11-27B]
than that in the fixed speed pump system. Synchronization of the pump head with
the system head results in reducing energy consumption.
2) The increase in the speed of the pump follows the increase in the flow rate. The
optimum speed of the pump is estimated to achieve the lowest power
consumption.
3) The pump efficiency for the variable speed system 0.84 – 0.88 as against the
efficiency variation in the range of 0.77 – 0.88 for the fixed speed system.
4) The power consumption for the variable speed pump varies from 62-132 kW
while for fixed speed system the observed range was 100-180 kW.
It is clear from the above analysis that the variable speed pumps can offer significant
energy saving in a pumping system where flow variations are large.
GPS-X Technical Reference