6 ms·
Whoever made this assumes that the chimney wall would be a perfect insulator, which absolutely cannot be the case if it's supposed to be a thin cloth or film ba
by chroem- 9y ago
Whoever made this assumes that the chimney wall would be a perfect insulator, which absolutely cannot be the case if it's supposed to be a thin cloth or film barrier. The air would cool to the same temperature as the surrounding atmosphere.
This will not work.
- sp332 9y agoIt only has to be a reasonably good insulator. And anything that can stand up to winds at kilometer altitudes will do fine.
- roceasta 9y agoI doubt it has to be a good insulator. The air is travelling up the tube at high speed and there isn't time for it to cool significantly before it emerges.
- chroem- 9y agoNo, it would have to be a very, very good insulator. You're talking about three miles of tubing exposed to high speed winds and large convective heat losses. Anyone who's taken a course on thermal power systems would know that this is absolutely preposterous.
- sp332 9y agoI'm not saying it's feasible or anything, but he's talking about moving air at over 100 miles per hour. It would only take a couple of minutes to get to the top.
- roceasta 9y agoRight, plus it's a 30 metre diameter tube. The bulk of the air moving up the centre would be insulated by the outer layers of air near the inner skin of the tube.
- chroem- 9y agoThat's not how convection works. It won't be moving quickly in the first place if it cools off. This whole farce of a thread is really tempting me to sink time into calculations to prove that this is absolute bullshit.
- kwillets 9y agoThe author also states in the FAQ that the air in the chimney will not undergo adiabatic cooling. If that were possible it would also not undergo expansion and would remain denser than the surrounding atmosphere.
- deleted 9y ago[deleted]
- bognition 9y agoChimneys do not require perfect insulators otherwise no chimneys would work. The biggest thing they do is prevent air mixing which in turn prevents a lot of energy exchange. This could work.
- chroem- 9y agoYou realize that other chimneys have an outside energy source and that this essentially amounts to a free energy device, right? I can scarcely believe that this is an actual level of argument that's occuring on HN.
- hn_throwaway_99 9y agoI am not qualified to evaluate the actual possibility of this device, and there are many points that don't seem plausible to me. However, the author is not arguing free energy. That would be like arguing wind turbines are "free energy". It's very clearly a solar powered device, with solar energy providing the heat that drives the air movement.
- guscost 9y agoI'm not qualified either but this is an important point, the energy is definitely available and photoelectric semiconductors are merely one way to harness it. Regarding the practical issues, what happens at night? Does it collapse under its own weight? How do you get it up in the sky in the first place?
- Thetawaves 9y agoThe upper troposphere cools as well, resulting in a maintained differential.
- indrax 9y agoThis is absolutely not a free energy device. It may be bunk, but it is an attempt at a heat engine. Or rather, an attempt to make an existing heat engine more efficient/ faster/ controlled. There is outside energy and it is already doing work. We want more heat transfer and more controllable weather.