Client: London Underground
Type of works: supply of large JM aerofoil fans
An old poster claimed that the BakerlooLine was the coolest place in hot weatherand at the time it was true. However, as commuters know, these dayssummer temperatures can frequently touch 30°C, and as a result London Underground has started a comprehensive up-grade of the existing tunnel and station ventilation fan network.
Research has identified that around three quarters of the energy used on the network is a result of train operation, which includes the energy required to move the train and losses occurred through friction braking. The rest is accounted for by the operation of the station and tunnel services, which inclu-des lighting and communication. This energy generates a significant amount of heat and subsequently ventilation of the stations and tunnels is essential to help remove this heat and reduce tempera-tures.
Here, Fläkt Woodsexpertise is crucial, with 100 years experience in the ventilation business the Company knows about all there is to know about moving air.
Trains moving through the tight deep-level tunnels push air forward through the tunnelsexplains Paul Wenden Engineering and Marketing Director of Fläkt Woods This is called the piston effect. This effect can produce a strong wind blowing though the tunnels and stations but so far it has proven difficult to use this air movement to expel warm air and bring in cooler air to provide sufficient cooling.
Over the past three to four years, a lot of unseen work has been going on. One of the main things was simply cleaning up and repairing the existing ventilation shafts. There are 160 ventilation shafts throughout the underground parts of the system, and Fläkt Woods is currently supplying fans for 8 of these mid Tunnel Ventilation Shafts on the Victoria Line. In some stations, fans measuring over 2.24 metres have had to fit through service doors no wider than 1 metre. The shafts, like the doors are narrow and extremely restrictive, No matter what shape we started with; we had to find a way of fitting our fans through says Paul Wenden Our engineers have had to go back to the drawing board to find a way of fitting a square peg through a round hole.The answer was as complex as it was simple. Fans that can be disassembled into segments, and then reassembled again once engineers have the space to work. Computer modellingof every made-to-order fan has ensured that what is delivered is a practical and energy efficient solution.