An evaluation of how the air-flow from ceiling-mounted-ESP outlet ducts affects moving cars

摘要

The Shin-Tomei Expressway, which was constructed as a bypass route for the Tomei Expressway to support economic activity in Japan, opened in April 2012. The Fujigawa Tunnel in this expressway, which is approximately 4.5 km long, has a large inner cross-section which is almost twice as large as that of conventional tunnels. Two systems of electrostatic precipitator (ESP) facilities have been installed in the tunnel to protect the environment around the exits of the tunnel. After studying ESP installation methods, civil engineering works, and economics for the Fujigawa Tunnel, ceiling base planks were set on the roadway of the tunnel. Then, the ESP, ESP fans and other facilities were placed on the planks. The treated air from the ESP is discharged slightly downward from the horizontal plane of the road surface in consideration of wall-friction loss caused by the ceiling-mounted arrangement. Although ESP systems are normally designed assuming that cars are traveling in tunnels, there is the possibility of a short circuit of air-flow if the ESP fans are started while the air velocity in the tunnel is extremely low because of the close distance between the inlet and the outlet. To clarify this issue, site-tests and numerical simulations for the wind velocity in the tunnel and the unsteady wind state upon operation of the ESP fans were done to evaluate the effect on moving cars. This paper reports a series of trials and the policy for starting the ESP fans.