Why MoJet? Benefits of the MoJet®

The reversible MoJet® tunnel ventilation system can increase the in-tunnel aerodynamic thrust by up to 100%, with reduced power consumption. To achieve such a significant improvement in performance, the MoJet® uses shaped nozzles which turn the airstream away from the tunnel soffit and walls. This reduces surface friction, minimising the Coanda Effect, where a reduction in static pressure due to the high jet velocity tends to deflect the jet towards any solid surface. The MoJet® represents a significant improvement over older technologies to reduce the Coanda effect, such as the Banana Jet® and airflow deflectors (see our power comparison paper).

MoJet Fan Cut-out

key benefits of the MoJet® are

Reduced number of jet fans

The innovative design results in markedly improved energy efficiency and fewer or smaller jet fans being required to provide the same degree of ventilation, as verified by independent measurements in full-scale tunnels. The reduction in the number of fans leads to lower procurement, installation and maintenance costs.

Reduction of up to 50% in power consumption

This leads to lower costs for energy and installed power, as well as a lower carbon footprint.

Reduced cabling costs

since MoJets® can be installed much closer together in a longitudinal direction than conventional jetfans.

During tunnel design and construction, the MoJet® can offer the following benefits:

A smaller tunnel cross-section

leading to a reduced requirement for construction materials and contributing to a faster construction programme. MoJet® nozzles do not encroach upon the traffic envelope, and can be installed very close to tunnel walls and soffits, reducing space requirements and construction costs.

Reduced spacing between fans

MoJets® can be installed at the portals and can be arranged longitudinally closer together in the tunnel – a significant advantage in short tunnels.

Smaller and lighter fans for the same aerodynamic thrust

This leads to improved handling during installation, as well as reducing overheads associated with commissioning and maintenance.

Additional ventilation capacity

For existing tunnels, additional ventilation capacity can be delivered without the need for installing tunnel niches.

How the MoJet® works

The MoJet® works by harnessing five beneficial effects into one aerodynamic device.