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General Science => General Science => Topic started by: Eddyb on 04/07/2019 01:34:07

Title: Could a 5.6m train in a 6m tunnel be used as the vacuum pump
Post by: Eddyb on 04/07/2019 01:34:07
Could a 5.6m diameter maglev train be used as the vacuum pump in a 6m diameter tunnel starting slowly at first and increasing the speed of each run until most of the air is pushed out the exhaust valve at the next 200 km passing station

In response to alancalverd I know about all the different things that did not work but I wonder if you could explain further about the inefficiency,

Do not forget that once there is only about 4t of air entering with every train once it is operational it would only be above atmospheric pressure in the last bit using the kinetic energy as it slows.
Title: Re: Could a 5.6m train in a 6m tunnel be used as the vacuum pump
Post by: alancalverd on 04/07/2019 07:35:04
Yes.This is how pumps work, though it wouldn't be very efficient. Brunel's Atmospheric Railway operated on the reverse principle of a vacuum pump driving a piston through a long cylinder to haul the train, but it failed as rats ate the greased leather valves.
Title: Re: Could a 5.6m train in a 6m tunnel be used as the vacuum pump
Post by: watermaaan on 24/07/2019 15:35:44
Very interesting!