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Author: Batman55Batman55 Date: Jul 1, 2008 04:01
It seems odd that as LUL attempts to cool down the tube, it is introducing
giant electric projectors at many stations, along with the illuminated
moving panels on the escalators. The stories in Railway Herald this week,
page 5 about cooling down, and page 6 about the heat producing equipment,
seem to show a lack of joined up thinking!
What might be more sensible is for equipment at every sub surface station to
be reviewed and every heat producing item examined to see how its heat
output could be reduced or eliminated. Every little bit might help!
MaxB
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Author: Tom BarryTom Barry Date: Jul 1, 2008 04:33
Batman55 wrote:
> It seems odd that as LUL attempts to cool down the tube, it is introducing
> giant electric projectors at many stations, along with the illuminated
> moving panels on the escalators. The stories in Railway Herald this week,
> page 5 about cooling down, and page 6 about the heat producing equipment,
> seem to show a lack of joined up thinking!
>
> What might be more sensible is for equipment at every sub surface station to
> be reviewed and every heat producing item examined to see how its heat
> output could be reduced or eliminated. Every little bit might help!
>
> MaxB
>
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Author: thagor2008thagor2008 Date: Jul 1, 2008 05:17
What surprised me was an item on the TV a while back saying that some
shaft extraction fans on I think the victoria line were being brought
back into use. Only now?? And why the hell were they out of use in the
first place?? Also I'd be interested to know the power consumption of
the most recent tube stocks compared to the old stocks since all power
used eventually ends up as heat. I wouldn't be surprised if like the
new 3rd rail surface stocks they use considerably more power overall
than older stocks and so contribute to the problem.
B2003
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Author: Colin RosenstielColin Rosenstiel Date: Jul 1, 2008 14:01
> Batman55 wrote:
>> It seems odd that as LUL attempts to cool down the tube, it is
>> introducing giant electric projectors at many stations, along
>> with the illuminated moving panels on the escalators...
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Author: John BJohn B Date: Jul 1, 2008 15:00
On 1 Jul, 22:01, rosenst...@ cix.co.uk (Colin Rosenstiel) wrote: >> Regen braking has a
>> place here, too, if you can shove the heat from the necessary
>> resistors outside.
>
> If it's regen braking, rather than rheostatic, the heat goes as energy to
> other trains and not into resistors.
Ish. On AC, absolutely right; on DC, you need banks of resistors as
well because putting it back to the grid if there isn't a conveniently
placed train to take it is Too Bloody Hard. However, given the traffic
density on LUL, most of the time there'll be someone accelerating
while you're breaking so it should work out OK...
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Date: Jul 1, 2008 15:32
"Tom Barry" blueyonder.co.uk> wrote in message
news:aCoak.189010$9x.103925@newsfe05.ams2> Regen braking has a place here, too, if
> you can shove the heat from the necessary resistors outside.
Quite apart from the fact that the resistors aren't likely to be needed
much in the central underground sections where there are lots of other
accelerating trains, I assume they put out no more heat than the
friction brakes would have done. They're more likely to be needed on the
extremities of the network where there may not be many other trains
around to absorb the power.
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Author: Tom BarryTom Barry Date: Jul 1, 2008 15:34
John B wrote:
> On 1 Jul, 22:01, rosenst...@ cix.co.uk (Colin Rosenstiel) wrote: >>> Regen braking has a
>>> place here, too, if you can shove the heat from the necessary
>>> resistors outside.
>> If it's regen braking, rather than rheostatic, the heat goes as energy to
>> other trains and not into resistors.
>
> Ish. On AC, absolutely right; on DC, you need banks of resistors as
> well because putting it back to the grid if there isn't a conveniently
> placed train to take it is Too Bloody Hard. However, given the traffic
> density on LUL, most of the time there'll be someone accelerating
> while you're breaking so it should work out OK...
>
Yes, that's what I was getting at. In mitigation, I hadn't read Cap'n
Deltic's latest screed in MR at that point, which suggests that
receptivity in DC networks is higher than previously thought, so you
might not need as much resistance capacity and associated cooling around
the place.
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Author: Tom AndersonTom Anderson Date: Jul 1, 2008 16:07
On Tue, 1 Jul 2008, John B wrote:
> On 1 Jul, 22:01, rosenst...@ cix.co.uk (Colin Rosenstiel) wrote:
> >>> Regen braking has a place here, too, if you can shove the heat from
>>> the necessary resistors outside.
>>
>> If it's regen braking, rather than rheostatic, the heat goes as energy to
>> other trains and not into resistors.
>
> Ish. On AC, absolutely right; on DC, you need banks of resistors as well
> because putting it back to the grid if there isn't a conveniently placed
> train to take it is Too Bloody Hard.
But there are places to send it other than the grid, surely? Supercaps?
Pumped storage? Flywheels? A giant laser firing into space?
tom
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Author: Tom AndersonTom Anderson Date: Jul 1, 2008 16:09
On Tue, 1 Jul 2008, Tom Barry wrote:
> According to TfL, the heating effect arises because of the incremental
> heating and cooling caused by each passing train's energy consumption.
> The frequency of trains means the cooling of the tunnel walls is that
> little bit less than the heating, so over the years the ground heats up
> because it never gets a long enough break between trains. This is
> rather borne out by the original Bakerloo Line claim that it was an
> nice, cool way to travel in the heat of the summer - it was decades
> before the effect was realised.
This seems like an extraordinary proposition to me. Could you refer me to
any documents giving more details?
> Presumably if you could shut the tube for a few years you could reverse
> it, but I can spot a couple of problems with that idea.
Or do a one-week shutdown and blow cold, damp air through the tunnels.
tom
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Author: Tom BarryTom Barry Date: Jul 1, 2008 16:41
Tom Anderson wrote:
> On Tue, 1 Jul 2008, Tom Barry wrote:
>...
>
> This seems like an extraordinary proposition to me. Could you refer me
> to any documents giving more details?
>
>
> tom
>
Yup, someone took notes at a TfL talk in March, which are online here:
http://www.freewebs.com/going_underground/Notes%%5Ffrom%%5FCooling%%5Fthe%%5FTub...
Relevant section:
"Most heat is generated from the equipment, brakes etc underneath the
train. Plans are being made to draw this heat out from under the trains
when they stop at platforms and then vent this heat out of the stations.
Obviously this would only work in those stations that have adequate
ventilation to street level..."
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