Cooling an island 3

Xenophile wrote:

>--- In spacesettlers, Ian Woollard wrote:
>
>>Ok. Idea for cooling an island 3.
>>
>>
>
>I could get into this.
>
>>Much as on the earth, the sunlight shines on the ground and the
>>ground heats up. This causes convection currents that rise up
>>towards the axis.
>>
>>
>
>Yep. Probably some weird swirling from coriolis.
>
>>Ok, now assume the end caps are shielded from direct sunlight.
>>(Thin aluminum shield spaced away at the sunlit end, other end is
>>fine.)
>>
>>
>
>Any reason it has to be aluminum? Iron is more abundant.
>
Doesn't matter, provided it's shiny. Actually doesn't have to be shiny,
but works better if it is. Aluminum is lighter though, which msy be
important, depending on where your habitat is.

>>If you do that, they will be cold, therefore any hot air from the
>>central axis will cooled there and sink. So there would be a
>>convection cell set up, going from the hot rim, to the axis, and
>>then it will get sucked to the end cap where the air will cool and
>>spiral out to the rim.
>>
>>
>
>So there are breezes, mainly from the center of the vallyes to the
>endcaps... no, wait... only at altitude do you have that, right?
>
>At ground level, you'd have... um...
>
No you'll get some wind at ground level going towards the center of the
habitat (except we catch the airflow in the pipes, mostly)

>>At the rim around the end cap you arrange for there to be funnels
>>that catch the cool air and pipe it longitudinally along the
>>habitat, so that the whole habitat shares the cool air through
>>distributed vents.
>>
>>
>
>Perhaps these funnels could be incorporated into the endcap
>mountains.
>
Could do that I suppose. Have an air inlet at the axis and some vanes.

>>The pipes are under the floor of the habitat- out in the vacuum
>>(incidentally they can be used as a transportation system as well).
>>
>>
>
>Pnuematic tubes. Cool.
>
Actually all this airflow can be tapped as a source of energy- the whole
habitat is collecting sunlight and heating it; the airflow this induces
contains all that energy. Stick a fan in the ventilation duct and you're
probably able to power the whole habitat.

Electric trains or cars might be more it

>>Ok, now the cooling isn't enough- the end caps aren't big enough.
>>So, the pipes (which are outside the habitat) may well need extra
>>vanes that are end-wise on to the sunlight, and hence they will
>>dissipate heat- the amount of distributed heat by the pipes and
>>the vanes is proportional to the area of the habitat; so the
>>solution scales with the size of the habitat.
>>
>>The only issues I can see is condensation. Still, most of that
>>could happen at the end caps and you can arrange for that to be
>>collected and be put back into some lakes. You'd certainly want to
>>ensure that the air pipes don't freeze up though.
>>
>>
>
>I'm sure there are wonderful ways to keep that air very, very dry.
>
Well if you do it may cause issues. People like humidity.

But the coldest bits would be the airpipes so water tends to collect
there if you're not careful. You don't want moldy pipes, so its
important to keep them clean and as dry as possible. Legionaires disease
would be bad, although I think it prefers it hot so it may be ok.

Pumping the condensed water off to be purified/returned to a
lake/taps/turned into rain would be a good idea I think.

>>Comments?
>>
>>
>I like it. How much temperature difference can you have? IOW, can
>you have snowboarding in the endcaps and skinnydipping in the
>valleys?
>
You can control the temperature at any point in the habitat by adjusting
the size of the airpipe vanes I think. So you can have mountains that
are 25 degrees centigrade cooler than the surroundings- it will freeze.