In article , Terry Harper
writes
"Roy Stilling" wrote in message
...

I posted a comment to the Mayors air-con competition on the LU website
the other week asking why, as their website says they pump thirty
million litres of water a day out of the system due to the rising
water table, that water can't be used to transfer excess heat from
aircon out too.

If that water is below ambient, then they could use it to spray the incoming
air to reduce its temperature, or to reduce the temperature of the outgoing
air. One or two little problems in the tunnels due to conductor rails, of
course. That could be solved by a system of inlet and exhaust ducts and
fans, whereas at present they use the trains as pistons in the close-fitting
tube tunnels to provide ventilation.
I still think the best solution is to cool the stations using
conventional A/C technology. Units exist for shops/factories, etc. which
have adequate cooling ability and these could be mounted in the top half
of the station tube - space up there. The gas/liquid coolant could
either be routed up stairwells/escalator shafts (doesn't take up too
much room) or through purpose drilled boreholes to the surface. The heat
exchanger could be mounted on top of the station.

Getting the station temperature down a few degrees would also cool the
tunnels (due to the piston effect) and probably then the existing
ventilation systems on the trains would be adequate - until the tunnels
are substantially cooler I can see no possibility of A/C on the trains
actually being practical.

--
John Alexander,

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