Talk:London Underground cooling

message: This promises to be a really interesting article and very significant over the next few years with environmentalism, Ken Livingstone's congestion charge, the 2012 Summer Olympics and media focus on London as 2012 approaches. Looking at it from the physics angle, please can you think about/address my comments:
I am reasonably sure the ground temperature in the deep tube is fairly constant summer to winter. Why don't the trains in summer 'cool' down much. Do they carry a lot of heat into the tunnels from when they were on the surface being heated by the sun?
What is the contribution from sun heating before they enter the tunnels?
Can (are) the trains painted in infrared reflective paint to reduce this?
How is the kinetic energy dissipated in regenerative braking stored? Does it go straight back into the power rails (I would think very inefficient) or is it stored perhaps in batteries which could also be used for train lighting perhaps?
The 50 gigawatts per day contribution from passengers confuses me and I think it needs looking at. If he refers to a period of time he should use energy. A power is an energy conversion rate so I would suggest it varies through the day peaking with the maximum number of passengers. Also at about 50 W per passenger, 50 GW needs 1E9 passengers to be using it at the same time, I don't think so.
:The passenger heat loads are indeed wrong. The original source is a TfL press release titled "LU briefing on Tube heat and ventilation issues" from May 2005, which states:-
::Each year the Tube's one billion passengers emit 56GW of heat each year and is equivalent to 63,925 100w light bulbs burning continuously.
:As you say, the dimensions don't stack up but the additional data with the light bulbs gives a clue. The press release should have said 56 GWh each year (GWh (gigawatt-hour) is a unit of energy).
:If you run 63,925 hundred-watt bulbs for a year, you use up 3925*100*365*24*3600 = 2.016e14J. One kilowatt-hour is equal to 3.6e6J: divide the first by the second and you get 56e6kWh, equal to 56GWh.  On the basis of this, I'm fairly sure that TfL's press officer mistakenly wrote 'GW' instead of 'GWh'.
:The external source referenced in the wiki article is The Londoner: Why does the Tube get so hot?, July 2005.  Its author garbled the information even more, by changing 'each year' to 'each day' and '56 GW' to '50 GW'. Fortunately, he kept in the bit about running 63,925 hundred-watt bulbs continuously so they must be from the same source.
:Annoyingly, I can't find any trace of the LU briefing on "Tube heat and ventilation issues" on TfL's website.  It seems to have vanished.  I'll alter the page to suit my interpretation, but if there's a flaw in the above reasoning, feel free to re-edit it.
:Ecb 21:49, 6 February 2007 (UTC)
thread_title: The beginnings of an interesting article: physicists, air conditioning, tunnelling etc engineers please contribute!

message: Is this for real?  —Preceding unsigned comment added by 74.202.89.125 (talk) 17:44, 29 September 2008 (UTC)
thread_title:  Ice block cooling? 

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message: It was exactly the info I needed Willem640 (talk) 18:09, 26 July 2019 (UTC)
thread_title:  To whomever made this page, thanks