"Tom Anderson" wrote in message
...
On Fri, 16 Jul 2004, Ted Maul wrote:
The London Underground are investigating the possibility of using water
to cool down underground stations.

It's an interesting problem, the cooling. It's easy to pump heat out of
the carriage into the tunnel (that's normal air conditioning), and that'll
work fine when the trains are above ground, but it's rather harder to get
heat from the tunnel to the outside. Three options spring to mind: pump
warm air out (which means moving a lot of air), transfer the heat into
water and pump that out (which means moving a bit of water, but
transferring a lot of heat), or transfer the heat into some kind of
reservoir on the train and then dispose of it when outside (which means
either pumping the heat out, or just using water to hold the heat and then
dumping it, neither of which is going to be that easy).

As I suggested some months ago, long low water tankers at front and back of
every train. The one at the rear sprays out a very fine mist of water which
will cool the air and then be drained out, taking the heat with it, just as
with any other water which gets into the underground system. I claim the
prize.
Cheerz,
Baz