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Cooling deep level tube lines

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Cooling deep level tube lines

Posted by Ant_C on Aug 8, 2019 11:49 am

I understand it is intended new 2030 deep level tube trains will have some form of integrated air-conditioning.  Does anyone have information on how this is to be achieved? If not I have a suggestion which is really a much-preferable extension of the interim experimental solution which might be considered by London Underground in the meantime.

Temporary solution – when temperatures on the, say, Central line between White City and Stratford exceed 30 C:  As Per  https://en.wikipedia.org/wiki/London_Underground_cooling “Different systems have been proposed to cool Underground trains, including the use of large blocks of ice inside the train. The blocks would be kept in refrigeration units, preventing them from melting completely”

Instead of ice use cheap and readily available sealed picnic “ice packs”. 50kg of these could be installed in wheeled insulated containers with battery-powered thermostatically controlled fans.  My calculations indicate two of these units per carriage would be capable of cooling the air in the carriage from 30 C to 20 C for the duration of the journey from White City to Stratford.  At Stratford the units would be substituted with fresh ones by LU staff (hired for the duration of the warm conditions) for the return journey to White City.  Both White City and Stratford have sufficient space and access to fresh air for commercial deep-freezes (rented for the duration of the warm conditions) to have fresh freezer packs available. The 50kg wheeled units would need to be secured appropriately to prevent theft/malicious damage. Similar approach to be used for other sections of the deep tube network

What do people think?

 

Re: Cooling deep level tube lines

Posted by Alasdair Anderson on Aug 8, 2019 12:14 pm

Do your calculations take into account the heat given off  by the passengers? If an average person gives off 100W of heat then a carriage full of passengers (say 100 persons per carriage - a very conservative estimate for rush hour conditions) would be generating 10kW of heat.
Alasdair

Re: Cooling deep level tube lines

Posted by Andy Millar on Aug 8, 2019 12:34 pm

See this really good link https://www.ianvisits.co.uk/blog/2017/06/10/cooling-the-tube-engineering-heat-out-of-the-underground/ which discusses the use of Ice Packs - I note it's based on an IET lecture.  Interestingly this states that passengers aren't the problem (or at least only 2% of it) which surprised me, but then I'm absolutely not a thermodynamics engineer.

Older report here http://content.tfl.gov.uk/lu-cooling-the-tube-programme-presentation1.pdf

My solution is to stay out of London as far as possible in the hot months, but I accept that this may not work for everybody 😊

In 2003 there was the offer of a cash reward of £100,000 to anyone who could find an "innovative, cost effective and practical way of cooling the Underground". But "despite more than 3,500 ideas being submitted from 60 countries, the prize has not been awarded, because the proposals received are either unworkable, unaffordable or were already being considered by London Underground". https://web.archive.org/web/20070930184514/http://www.london.gov.uk/londoner/05july/p4b.jsp?nav=news

Keep the ideas coming...despite being a fan of the Underground in general (in a mildly train spottery way) I LOATHE it in the summer.

Cheers,

Andy


 
Andy Millar CEng CMgr IET Mentor / IET PRA uk.linkedin.com/in/millarandy

Re: Cooling deep level tube lines

Posted by Alasdair Anderson on Aug 8, 2019 12:55 pm

Andy,
The passengers only being responsible for 2% surprises me also. If the heat has built up in the clay over the years it seems to me that extracting the heat at night in winter by circulating cold air (with or without trains) might help. However I am sure that the responsible engineers have already thought of any idea I might come up with in my lunch hour....
When I was based in the city my solution in the summer was to walk instead of using the tube (mind you, that was my solution in Autumn, Winter and Spring also as it was quicker than a single stop on two separate tube lines)
Alasdair

Re: Cooling deep level tube lines

Posted by Andy Millar on Aug 8, 2019 12:57 pm

Hi,

Just had a thought on the passenger heating effect - they don't seem to mention the fact that even if passengers have a negligible effect on the overall average temperature, a crowded train (I'm thinking jam packed Victoria line at 8:45 or 5:15) will be hotter for each individual passenger due to the combination of the ambient temperature and being crammed in with the other organic heat generators. So my two penn'orth:
  1. More through carriage (continuously open) trains a la the sub surface lines (District, Circle and Hammersmith & City) to improve airflow. I assume that's being considered (along with improved energy efficiency and aerodynamics which I know is being considered).
  2. Move away from the "9:00 start, 5:00 finish" obsession. For most organisations why stick to this?
  3. Move away from the "we want you in the office every day" obsession.
  4. Move organisations out of London. It's a ridiculously expensive place to run a business anyway.
  5. Finish Crossrail 😏 And Crossrail 2.
  6. And if none of 1-4 above are deemed practical, at least allow blokes to wear shorts to work!
Interesting that only one of these requires effort and expenditure on the deep tube lines, and only two involve TfL. Of course these two are the only ones engineers can help with.

Cheers,

Andy
Andy Millar CEng CMgr IET Mentor / IET PRA uk.linkedin.com/in/millarandy

Re: Cooling deep level tube lines

Posted by Andy Millar on Aug 8, 2019 1:03 pm

And absolutely I agree about walking. I've had some very interesting walks from Paddington to Savoy Place and back, it's amazing what you can come across. (I tend to navigate through London by the compass bearing approach down the back streets.) Sadly, mostly I'm dashing from meeting to meeting when I'm up there (because I try to cram as much as I can in at once to make the trip worth while) so don't usually get the opportunity.

I think best walk was from Paddington to the House of Lords which was almost entirely through parkland. But I digress...and lunch smells cooked...

Cheers,

Andy
Andy Millar CEng CMgr IET Mentor / IET PRA uk.linkedin.com/in/millarandy

Re: Cooling deep level tube lines

Posted by Ant_C on Aug 8, 2019 1:04 pm

Re "Do your calculations take into account the heat given off  by the passengers?" ... Only indirectly ... I took the view of the "... passengers only being responsible for 2% .. " of the heat and concentrated on the the mass of air inside each carriage (approximately 173 kg) ... I made a reasonable (?) assumption each carriage-worth of air would need to be re-cooled ten times from 30 C to 20 C on the journey from White City to Stratford

Re: Cooling deep level tube lines

Posted by Alasdair Anderson on Aug 8, 2019 1:19 pm

I don't know if it is a 'reasonable' assumption, but likewise I don't know if it is unreasonable. If half of the air is replaced at each stop by passengers getting on and off it may be about right.

Re: Cooling deep level tube lines

Posted by Ant_C on Aug 8, 2019 3:43 pm

Hmm ... I think it would be worth trying to persuade London Underground to perform some experiments .. I believe they could be performed very inexpensively ... ... does anyone know a good contact there? BTW I was thinking about your "Do your calculations take into account the heat given off  by the passengers? If an average person gives off 100W of heat" comment ... presumably the rate of heat transfer depends on the ambient temperature ... in a (sweltering) 37 C carriage the rate of heat transfer from each passenger will be nil as this is blood heat.  Above 37 C all of us must be dependent on the state change of liquid water (in the form of sweat) to water vapour for cooling

Re: Cooling deep level tube lines

Posted by mapj1 on Aug 27, 2019 5:50 pm

Do we  need to cool the air at all, or just remove the moisture, so that cooling by sweating actually works properly ? It is quite possible to be comfortable in high temperatures, so long as it is dry and hot. In the mean time airflow, could trains not only be walk through but also effectively be made open at the ends ?
regards Mike

Re: Cooling deep level tube lines

Posted by Foffer on Sep 3, 2019 9:28 pm

mapj1:
Do we  need to cool the air at all, or just remove the moisture, so that cooling by sweating actually works properly ? It is quite possible to be comfortable in high temperatures, so long as it is dry and hot. In the mean time airflow, could trains not only be walk through but also effectively be made open at the ends ?

I like your idea.  I think we all suffer much more in high humidity and this could be a solution to give a much more comfortable ride.

As regards cooling, how about carrying out the a/c gas compression and cooling phase outside the underground in an open air plant and then charge each train with enough compressed ambient temperature a/c gas to cool the train for its journey?
Foffer, Herne Bay, Kent, UK

Re: Cooling deep level tube lines

Posted by Ant_C on Sep 4, 2019 11:15 am

Re Foffer: "As regards cooling, how about carrying out the a/c gas compression and cooling phase outside the underground in an open air plant and then charge each train with enough compressed ambient temperature a/c gas to cool the train for its journey?" 

It appears the London Underground 2030 solution includes something similar .. LU's Sharon Duffy 2017 presentation ... includes ... per Page 45 ( "In train hybrid cooling") in the pdf:
https://static.smallworldlabs.com/iet/user_content/files/091/756/91756859/f6310b110724334fc92067b13fe3b198-iet-cooling-the-tube---railway-tpn-08-06-17.pdf
... shows the on-board A/C being used to cool a "thermal mass" of coolant to sub-zero C temperatures while the carriages are above ground ... and then use this stored cool mass to cool air inside the carriages during the deep-level tube sections of the journey.
For the intervening years between now and 2030 I have proposed an "interim work-around" to LU using portable cooling units to be deployed when the temperatures become uncomfortable for passengers ... no response as yet ... :-)

 

Re: Cooling deep level tube lines

Posted by Benyamin Davodian on Sep 4, 2019 12:41 pm

Hello,
It is customary to think that today's technology is more advanced than before, but sometimes the opposite is true. Ancient technologies of natural cooling relied on smart design already implemented in the construction itself. These technologies, like today's air conditioners, were based on lowering the temperature of the air inside the building space through pressure change and humidity levels, but unlike air conditioners capable of producing an interior environment tailored to user requirements regardless of weather conditions, the effectiveness of traditional methods depended on the existence of External climate factors, such as external winds in the building environment.

One of the oldest methods of cooling was using cooling towers. The cooling towers were based on the downward flow of air in the structure. Air movement is created by evaporation of water at the top of a tower, followed by a mass of colder and dense air. Pressure differences between the same cold air and the warm air around it cause the cold air to sink downwards. The wind flow near the upper opening creates a suction of the cold air outward, but by geometric design or by adding a wind turbine, the horizontal wind flow could be tilted towards the inside of the tower. In later periods, blowers were also used which increased the air suction rate when there was no wind. The cooling towers differ in the way water is supplied to the air - some use the air transfer through moist mattresses and some use fogs that formed a cloud of small droplets that evaporated completely before reaching the bottom of the tower.

This ancient method is rarely used even today and can be seen in the cooling tower in Kibbutz Neot Smadar. The tower, which is 38 m high, is located in the Arts House and was completed by the kibbutz members in 2001. At the end of the tower is a windpipe that pulls the air in from outside, at the bottom of the building is a pool that collects the minimal drops that go down and through a pump (the only means of combined energy needed) In the process) the water is flowed back up and the process is re-energized. The cold air is transmitted via underground channels to all parts of the large building, creating a comfortable and pleasant indoor climate in the environment.
Attached files
Regards, DAVODIAN BENYAMIN

Re: Cooling deep level tube lines

Posted by Calvin Barrows on Feb 13, 2020 11:18 pm

I would share with you my hypothesis on why London Underground and similar Metros worldwide suffer overheating. https://drive.google.com/file/d/1w18eRNzbUKd29X9ajTCg2XFTJbDbCr_-/view?usp=drivesdk

https://www.bbc.co.uk/programmes/p07qyjl5

Kind regards Calvin

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