Energy saved when a centrifugal pump or fan is speed-controlled instead of throttled. Affinity P ∝ N³ makes small speed reductions huge energy wins.
Formula
$$ P(N) = P_\text{full} \cdot \left(\frac{N}{N_\text{full}}\right)^3 $$
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| $P_\text{full}$ | Shaft power at rated speed | kW | pump curve |
| $N$ | Operating speed | % of full | VFD reading |
| $h$ | Operating hours | h/yr | operating profile |
Sources
- IMO MEPC.282(70) - SEEMP energy-efficiency measures.