Cooling the tube – Engineering heat out of the Underground (2017)
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Re: Cooling the tube – Engineering heat out of the Underground (2017)
#2"Over the years, the heat from the trains soaked into the clay to the point where it can no longer absorb any more heat. Tunnels that were a mere 14 degrees Celsius in the 1900s can now have air temperatures as high as 30 degrees Celsius on parts of the tube network."
Re: Cooling the tube – Engineering heat out of the Underground (2017)
#3"Over the years, the heat from the trains soaked into the clay to the point where it can no longer absorb any more heat. Tunnels that were a mere 14 degrees Celsius in the 1900s can now have air temperatures as high as 30 degrees Celsius on parts of the tube network."
Similar issues can happen with geothermal heating/cooling if it's unbalanced - eventually the ground temperature changes and you have to dig deeper or stop using it.
Re: Cooling the tube – Engineering heat out of the Underground (2017)
#4Regenerative braking would improve a lot with not just the heat issue, but also air quality. Commuters on the London Underground get a characteristic grey/black snot from the brake dust they inhale. If you stare into the tunnel after a train left you can literally see a haze of brake dust in the air.
Re: Cooling the tube – Engineering heat out of the Underground (2017)
#5Regenerative braking would improve a lot with not just the heat issue, but also air quality. Commuters on the London Underground get a characteristic grey/black snot from the brake dust they inhale. If you stare into the tunnel after a train left you can literally see a haze of brake dust in the air.
Yeah, they mention it with a "grid balancing issue" but it seems that could be solved by adding under-floor battery packs to the trains or the stations themselves - store braking energy to restart the train afterwards.
Re: Cooling the tube – Engineering heat out of the Underground (2017)
#6Regenerative braking would improve a lot with not just the heat issue, but also air quality. Commuters on the London Underground get a characteristic grey/black snot from the brake dust they inhale. If you stare into the tunnel after a train left you can literally see a haze of brake dust in the air.
I wonder if you could fit a magnetic braking system mainly at platforms, when engaged trains would be slowed. That could reduce weight on the trains themselves?
Thinking wildly, tube trains are like pistons (they're actual plungers, I guess) if you had a smooth walled section of tunnel then you could have a seal at the head of the train that fans out and provides pneumatic braking, you could maybe use the pressure to drive the ventilation system. Unlikely to be practical (you'd have to have a pre-platform door to prevent all the passengers from getting exposed to the pressure increase, I think).
Re: Cooling the tube – Engineering heat out of the Underground (2017)
#7Regenerative braking would improve a lot with not just the heat issue, but also air quality. Commuters on the London Underground get a characteristic grey/black snot from the brake dust they inhale. If you stare into the tunnel after a train left you can literally see a haze of brake dust in the air.
Yeah, they mention it with a "grid balancing issue" but it seems that could be solved by adding under-floor battery packs to the trains or the stations themselves - store braking energy to restart the train afterwards.
Less batteries and more ultra capacitors. You might need to handle power requirements in the range of 5-20MW, albeit for just a minute or so.
Re: Cooling the tube – Engineering heat out of the Underground (2017)
#8Regenerative braking would improve a lot with not just the heat issue, but also air quality. Commuters on the London Underground get a characteristic grey/black snot from the brake dust they inhale. If you stare into the tunnel after a train left you can literally see a haze of brake dust in the air.
I wonder if you could fit a magnetic braking system mainly at platforms, when engaged trains would be slowed. That could reduce weight on the trains themselves? Thinking wildly, tube trains are like pistons (they're actual plungers, I guess) if you had a smooth walled section of tunnel then you could have a seal at the head of the train that fans out and provides pneumatic braking, you could maybe use the pressure to…
Magnetic (eddy current) brakes work by converting kinetic energy into heat, which doesn't really solve the problem here. I'm not sure if anyone has devised a system that actually captures electrical energy from the braking action, or if such a thing is even plausible.
Re: Cooling the tube – Engineering heat out of the Underground (2017)
#9Earlier quoted context omitted.
I wonder if you could fit a magnetic braking system mainly at platforms, when engaged trains would be slowed. That could reduce weight on the trains themselves? Thinking wildly, tube trains are like pistons (they're actual plungers, I guess) if you had a smooth walled section of tunnel then you could have a seal at the head of the train that fans out and provides pneumatic braking, you could maybe use the pressure to…
Magnetic (eddy current) brakes work by converting kinetic energy into heat, which doesn't really solve the problem here. I'm not sure if anyone has devised a system that actually captures electrical energy from the braking action, or if such a thing is even plausible.
It'd at least solve the dust break-pad dust issue
Re: Cooling the tube – Engineering heat out of the Underground (2017)
#10Earlier quoted context omitted.
Yeah, they mention it with a "grid balancing issue" but it seems that could be solved by adding under-floor battery packs to the trains or the stations themselves - store braking energy to restart the train afterwards.
Less batteries and more ultra capacitors. You might need to handle power requirements in the range of 5-20MW, albeit for just a minute or so.
Definitely. The bonus is that they wouldn't have to be on the train. And the tube electric system is DC already as well. This sounds like an engineering problem that is largely already solved.