fan efficiency

Fan efficiency is the ratio of useful air power delivered to the input power required by the fan and motor system. In mining ventilation, efficiency matters because fans often run continuously and energy costs can be significant. However, the most important efficiency concept is not the peak catalog number—it is efficiency at the actual duty point (Q@Ps) in the mine system.

A fan can be “high efficiency” on paper but perform poorly if the operating point is far from its efficient region. This can happen when the fan is oversized, when system resistance changes significantly, or when duct losses and leakage move the duty point to higher static pressure than expected. Operating off the efficient zone can increase power consumption, noise, and vibration, while still failing to deliver end-of-duct airflow.

Practical efficiency improvements typically come from two directions:

• Match equipment to the real duty point: select based on the curve at the required Q@Ps, not free-air ratings.
• Improve the system: reduce duct losses, improve routing, seal leakage, and remove restrictions so the required Ps drops.

VFD control can also improve overall efficiency when the required airflow varies over time or when resistance changes with mine development. By adjusting speed, the fan can stay closer to an efficient and stable operating zone rather than running fixed-speed and wasting pressure. That said, VFD is not a substitute for good ducting and network management—system improvements often deliver the biggest efficiency gains.

Bottom line: in mining ventilation, fan efficiency is a duty-point and system topic. The most efficient fan is the one that delivers required airflow reliably at Q@Ps with stable operation, reasonable margin, and minimal avoidable system losses.