Aircon on the Tube

[317653]

Only the sub surface stock is. The new Victoria line trains most certainly are not and are already heating up.

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2009 TS are terribly hot inside the carriages, how comes the driver gets air con (or much colder air than the passengers as I expreienced in the cab of one)?

the 1967 Ts are much better at being ventilated. That is the only downside I have a bout the 09 stock

 

[trentside]

I believe the heat issues with the 09TS will be improved once the regenerative braking has been switched on. This can't be used while the 67TS are still in service.

 

[317653]

Oh right, so how come the driver cab has very cool air in them?????:roll:

 

[jon0844]

The 09 stock blows quite warm air inside, but I am willing to accept that this will be vastly cooled when we get the regenerative braking, so fingers crossed.

It does feel like the heating is on inside the trains at the moment. I was on the Picadilly Line today and it was just fine. As was the Northern Line (which is similar stock is it not?).

 

[DavidBusDriver]

Hate to say it, but maybe the driver requires the air conditioning since they are on the train for a much longer time than the average passenger.

 

[jon0844]

365s have an in-cab air conditioning system. For one thing, it will require a lot less energy to operate in a small cab, than a large open train carriage.

I think a driver deserves what little creature comforts they can have (and that some drivers won't break or deface!).

 

[Eagle]

The 09 stock blows quite warm air inside, but I am willing to accept that this will be vastly cooled when we get the regenerative braking, so fingers crossed.

Warm's a bit of an understatement, if you ask me.

I was on a full-and-sardines Victoria 09 train from KX–StP to Oxford Circus on Maundy Thursday, in the morning peak. In an enormous multilayered furry turtle costume. This is the day when it was 28 °C outside in the shade. In the space of four minutes my insides turned to mock turtle soup, no thanks to the warm aircon.

 

[trentside]

Oh right, so how come the driver cab has very cool air in them?????:roll:

The drivers cab has a separate air conditioning unit. The carriages have forced air ventilation, which takes in air from the tunnels to cool the train.

It does feel like the heating is on inside the trains at the moment. I was on the Picadilly Line today and it was just fine. As was the Northern Line (which is similar stock is it not?).

It certainly does feel like the heating is on. I think such temperatures would be appreciated on the outer reaches of some lines during the winter. The 67TS don't suffer the heat problem either.

The Northern line 95TS is not that similar to the 09TS. The 95s were designed by Alsthom (along with the Jubilee fleet of 96TS) while the 09s are from Bombardier, and are actually based on their existing Movia range. The major difference with the 09TS is that they are slightly larger, taking advantage of the Victoria lines larger loading gauge. This does mean that the 09TS cannot leave the Victoria by rail, to get to Acton works for example.

 

[Rational Plan]

London Underground are looking at air conditioned deep trains in the future.

They call it their Evo concept.

Basically they are looking at a semi-articulated trains. Made of a light weight aluminium design, passive steering bogies, all double doors with through gangways between cars and a lower floor. From the picture supplied it looks similar to the Xtropolis design pitched for Crossrail. There would be two double doors per articulated section, with both doors practically next to each other. Each carriage would be much shorter than current stock. The aim is to reduce power consumption from 0.42 Kwh per passenger km to just 0.26 kwh/ per pkm. This would produce much less heat in the tunnels and allow air conditioning on the trains. Even if that does not quite work out the less heat put in to the tunnels the better.

 

[whhistle]

Why can't the hot air just be cooled? Isn't this how cars work with air conditioning when you put the little button saying "take air from inside the car" to thie "on" position?

If the trains contstantly draws in the air, cools it, then pushes it back into the carriage, then eventually it'll be cooling the cool air. A lot would escape when the doors open in stations but at least it would stop the hot air being expelled into the tunnels?

 

[SS4]

Why can't the hot air just be cooled?

Isn't this how cars work with air conditioning when you put the little button saying "take air from inside the car" to thie "on" position?

If the trains contstantly draws in the air, cools it, then pushes it back into the carriage, then eventually it'll be cooling the cool air. A lot would escape when the doors open in stations but at least it would stop the hot air being expelled into the tunnels?

Don't forget the heat generated by the air-con units themselves which also needs to be expelled. In tunnels you'll also need to be aware of the effect on air pressure when you're sucking out hot air and expelling it behind you.
Air-con would work on the trains and in tunnels but it would be at the expense of stations which would be too hot. The only other alternative is vents to the surface but then you bring in the weather

 

[whhistle]

Also, while I note it would reduce capacity, why not just have a section at the front / rear of the train to house the equipment? Yes, this may take up 6/8 seats but that is nominal for the gains which would happen as a result.

 

[Peter Mugridge]

Well, there is precedent for having equipment of some sort or another taking up that sort of space at the ends of a unit:

http://www.20thcenturylondon.org.uk...=true&currentPage=4&current_browser_object=38

( Looks a lot nicer than the current generation of tube stock as well! )

 

[WinterChief]

That's 6/8 seats LU cannot afford for comfort. Plus the standing capacity. Those previous stocks were in the days when transformers/ compressors/ contactors were not smaller than a small sofa!

The pressure vents (as they are known as) are exactly that, the do not cool anything, they just provide the passenger with a breeze across their face which makes them feel cooler.

The heat generated is by the brake resistor, to which a fan blows air to cool them called surprisingly the brake resistor fans, (Rheo brake only).

Regen is used and 'turned on', however, it only comes on when the track needs it (when another train is pulling away in the same substation section), when the train can provide it - Only when braking (The train voltage must be higher than the line voltage). And the amount of time the train spends braking is reduced (to increase braking points and faster trains per hour) so not much is particularly going into regen in the first place. If regen is not available, rheo is used along with brake blend of friction brakes below around 10mph.

 

[es373]

That's 6/8 seats LU cannot afford for comfort. Plus the standing capacity. Those previous stocks were in the days when transformers/ compressors/ contactors were not smaller than a small sofa!

The pressure vents (as they are known as) are exactly that, the do not cool anything, they just provide the passenger with a breeze across their face which makes them feel cooler.

The heat generated is by the brake resistor, to which a fan blows air to cool them called surprisingly the brake resistor fans, (Rheo brake only).

Regen is used and 'turned on', however, it only comes on when the track needs it (when another train is pulling away in the same substation section), when the train can provide it - Only when braking (The train voltage must be higher than the line voltage). And the amount of time the train spends braking is reduced (to increase braking points and faster trains per hour) so not much is particularly going into regen in the first place. If regen is not available, rheo is used along with brake blend of friction brakes below around 10mph.

Great post mate

 

[futureA]

Why can't the hot air just be cooled? Isn't this how cars work with air conditioning when you put the little button saying "take air from inside the car" to thie "on" position?

If the trains contstantly draws in the air, cools it, then pushes it back into the carriage, then eventually it'll be cooling the cool air. A lot would escape when the doors open in stations but at least it would stop the hot air being expelled into the tunnels?

You can't 'just cool' something. Cooling is the transfer of heat from one place to another place. That is why the back of your fridge is so warm. Heat from inside the fridge is being transfered to the radiator at the back. All cooling and air conditioning systems work this way. The air conditioning in your car is pumping the heat outside.

The reason why cooling the tube is so difficult is because there is nowhere to transfer the heat to. In a building, you can transfer heat to the surrounding air but in a tunnel 30 metres under ground you don't have many options.

As for just air conditioning the trains, this might make the situation in tunnels/ stations much worse than it is now.

 

[es373]

Put your hand next to the fan on an A.C unit and tell me what you feel.
Heat.
Which is pretty much the reason why LU are finding it hard to cool the tube.

Personally I don't think it need it - it's been without it for 200 odd years so why bother now? The only thing that would be viable is to install huge coolant fans that blow air down a shaft into the tunnels. I couldn't see that being effective either.

Unless they some how manage to design something that dissipates the exhaustive heat without sacrificing the loading gauge.

 

[150001]

I always thought that LU should fit fans into the roof of the trains inside and you know in offices and classrooms you have fans that are powered by electricity which cool you down because of the spinning, why can't you have them in trains. They work in offices and are simple.

 

[es373]

They are in the trains. I think it's only 2 stocks that don't have them. C and A.
If you have warm air in an environment putting a fan there doesn't cool the air. It just shifts the warm air around and if you want to get scientific it actually does heat the air up (very minimal though) as the molecules rapidly hit each other which is friction and a byproduct of friction is heat.

I don't think it would happen for a long time yet.

 

[ralphchadkirk]

I always thought that LU should fit fans into the roof of the trains inside and you know in offices and classrooms you have fans that are powered by electricity which cool you down because of the spinning, why can't you have them in trains. They work in offices and are simple.

Because all you will be doing is blowing hot air around. Fans only work if there is a source of colder air - such as an open window, or A/C vent.

 

[jon0844]

It would be better to have fans taking the hot air out of the train - and drawing the cooler air from the floor up. But, at some point there's nothing you can do as all of the air is now hot and humid.

Reducing the humidity would actually make you feel more comfortable in lieu of air conditioning, but I am not sure how easy it would be to do that; you'd need somewhere to drain the water away!

 

[ralphchadkirk]

Reducing the humidity would actually make you feel more comfortable in lieu of air conditioning, but I am not sure how easy it would be to do that; you'd need somewhere to drain the water away!

Start giving away free water again!

 

[es373]

You are talking about Air Conditioning jonmorris0488.
Take the hot air out of the train and replace it with what? Even hotter air from the tunnels? Its a HUGE feat of engineering boring shafts down to the tunnels. It wont happen!

Then you'll get the waste water exhausting from the A/C unit, where's that gonna go? On the track/sleepers... Whats that going to cause? Voids in the track bed... What does that mean? Broken rails and sleeper replacement a reoccurring nightmare!

 

[jon0844]

No, I meant remove the moisture only, not cool the air. Obviously a proper air conditioning system would do both but leave you with all that hot air.

Dehumidifiers are of course just as impractical without major expense.

 

[Daniel]

Start giving away free water again!

There are several strategic points around the network with stored emergency water. Last time I gave some out was at Golders Green after trains had been stalled in tunnels for 1hr 30+ ... but we still have it!

 

[LE Greys]

You are talking about Air Conditioning jonmorris0488.
Take the hot air out of the train and replace it with what? Even hotter air from the tunnels? Its a HUGE feat of engineering boring shafts down to the tunnels. It wont happen!

Then you'll get the waste water exhausting from the A/C unit, where's that gonna go? On the track/sleepers... Whats that going to cause? Voids in the track bed... What does that mean? Broken rails and sleeper replacement a reoccurring nightmare!

Cool certain stations and rely on the trains to distribute cold air throughout the tunnels. The trick is to cool sufficient air to allow it to sink to platform/trackbed level (so Oxford Circus might be extremely cold) which partly forces warm air upwards and out of the station entrances. The piston effect from trains distributes cold air throughout the tunnels (the trains themselves have conventional pressure ventilation) and that cools nearby stations, again forcing warmer air up to street level.

I think it works in theory, but you need about twelve humungous air-con plants in central London.

 

[HSTEd]

Short of fitting enormous arrays of PVC pipes on the floor of the tunnel in the platform at every station and pumping enormous quantities of water cooled by an evaporation mechanism topside.... there ain't much that can be done.

So will the regenerative braking ever put energy back into the grid or will it keep defaulting to rheostatic if there is no net demand for power on that substation?

 

[es373]

The regenerated electricity is stored in capacitors/batteries for use with train auxiliaries. If you're referring to the 09 stock then im sure Winter Chief can comment as he knows his stuff when it comes to LU rolling stock.

 

[WinterChief]

So will the regenerative braking ever put energy back into the grid or will it keep defaulting to rheostatic if there is no net demand for power on that substation?

It does, on occasions. Say if one train is pulling away therefore drawing power and the train behind it is slowing down (therefore braking) in the same substation section. The regen will go back in the track. For the process to work the track has to be at a lower voltage than the train. The track must require it (ie, if there is so much current draw buy a few other trains) and a train has to be braking (or creating power by braking) in that section.

Quite a few contributory factors come in for regen to work fully. But it has been proven to be very effective when it works. Mostly in the peak.

 

[LexyBoy]

There was an interesting article in New Scientist recently on this very topic. The article is online but only available for subscribers, but there is an interesting gallery which can be viewed. Something which is pretty obvious, but which I hadn't thought of, is that a lot of the heat is stored in the surrounding clay. For the first decade or so of the Tube lines' operation, they were quite cool, but the energy use in them has heated the ground such that it is no longer a heat-sink.

Also talked about a couple of interesting ideas, such as trains carrying blocks of ice which would be used to cool the train when underground, and re-frozen on the overground parts. Maybe effective, but probably not so great for energy efficiency! The article also talks about the work on the Victoria line and proposed new trains (as described above)

I always thought that LU should fit fans into the roof of the trains inside and you know in offices and classrooms you have fans that are powered by electricity which cool you down because of the spinning, why can't you have them in trains. They work in offices and are simple.

This is what the new Victoria line trains do - blow air in from the outside to create a "cooling" draught. The problem is that this doesn't work if the air is too warm, or too humid - it will just be blowing hot air at you.

It would also be rather hazardous for anyone over 4'6 tall